Quantum 2 Mirror-Imaging Project

[Charivari]

For near unto two years now, I’ve been in the possession of a slightly oddball pair of Quantum 2s (S/Ns 1020711/1020712). It’s been a long, involved process getting everything working on these and even now there remain a few things to fix. I have managed to improvise a few fixes to get them working sufficiently to enjoy their sound and recognize that the non-mirror imaged design was greatly hobbling the imaging.

Here’s an old picture from way back in Sept 2004:
http://i30.photobucket.com/albums/c301/jpvanson/System%20Pics/Quantum2old.jpg

Fortunately, a few months back, John (jguzman21) encountered a single beat Quantum 2 sans most of the drivers with the mirror driver arrangement of my pair. He very kindly offered it to me, but it was in Colorado and I’m in Washington. Brian (brainsmasher) stepped in and generously offered to pack the beast up and ship it up to SeaTac, just 2.5 hours away from me, via Forward Air. It recently arrived and my mirror-imaging project has taken off.

After being lost for the better part of an hour in a rather large industrial complex consisting of several square miles worth of warehouses, I was able to find the local Forward Air office. It was tucked in behind a few buildings and trailers from the street with the only sign visible to the warehouse across the way and most certainly not from the two main roads on either side. There, a forklift operator who appeared to be in a perpetual hangover loaded the pallet with my cabinet into the back of my truck. I gave the pallet to some friends who were in need of firewood, returned home, and carried my prize in.

http://i30.photobucket.com/albums/c301/jpvanson/Q2%20Mirror-Imaging/1.jpg

The bottle and sledge in this picture of the box posted by brainsmasher had me a little worried about what I might find, but the fears were unjustified. To say that Brian is a good packer is an understatement as the flood of foam peanuts (that still haunt my apartment despite my multiple attempts to clean) can attest to.

So, what’s in the box?

http://i30.photobucket.com/albums/c301/jpvanson/Q2%20Mirror-Imaging/2.jpg

It came with a single non-functioning EMIT (working now after disassembly and resoldering the contacts), a single midrange dome with broken tinsel leads, and a host of Radio Shack/Realistic drivers thrown in as some attempt to replace bad or broken originals. (The extra polyfill from behind the woofer and around the crossover were removed for this picture.) There was also strong evidence that this was once the favorite speaker of a pet canine, but good ol’ fashioned soap, water, and a brush made short work of that. The level pots were green with corrosion and a not-so-quick cleaning with crocus cloth after using a knife to scrape the worst of it off later brought them back into spec. The cab itself has the wear and tear that comes with nearly 30 years of use and abuse and after I take the pair down to Vancouver for a face off against a pair of AR-9s (provided I can repair the crossovers in time), I’ll likely pull all the drivers and get busy sanding and oiling the veneers to take care of all but the worst of the damage and refresh the appearance.

[Charivari]

One of my existing cabinets need give up its drivers to bring life to this hefty hunk of particle board (right around 130lbs on its own according to the freight with the estimated weight of the box and packing subtracted). So, I chose one that despite my fondness for its front appearance has suffered a fair bit of veneer damage to the top and back.

http://i30.photobucket.com/albums/c301/jpvanson/Q2%20Mirror-Imaging/8.jpg

Hmm, does that veneer pattern look familiar? It should to those of you who have viewed the Quantum 2 brochure …

http://www.bobbyshred.com/images/Q2.jpg

It would seem the cabinet’s veneer came from the same log and was likely made just before or just after the one that came to represent the model to all interested in purchasing their own set.

The drivers after removal:

http://i30.photobucket.com/albums/c301/jpvanson/Q2%20Mirror-Imaging/7.jpg

To return to the topic at hand, the drivers should drop right in – and most do -- but a certain problem arose. This new cabinet (S/N 7103657) does not have the provisions for a very special trait not shared by all Q2s.
The original cabinet has this:

http://i30.photobucket.com/albums/c301/jpvanson/Q2%20Mirror-Imaging/3.jpg

To house behind a circular grill cloth this driver:

http://i30.photobucket.com/albums/c301/jpvanson/Q2%20Mirror-Imaging/4.jpg

Curses, foiled again! … but not for long.

[Charivari]

With the promise of free beer and the excuse to catch V for Vendetta at the local movie theater, I was able to lure my best friend over from Seattle with his plunge router and Jasper jig. The cabinet may not have been built for a rear EMIT, but we were going to fix that oversight.

After a delay of a few hours thanks to some hilarious antics due to the stupid act of yours truly involving an old keg 1/3 full of 8 year old stale beer and the need for clean-up and airing out, we set up to create the circular depression designed to hold the rear EMIT and the grill.

http://i30.photobucket.com/albums/c301/jpvanson/Q2%20Mirror-Imaging/5.jpg

As you can see, the lip of the sides being a touch over ¼” tall caused need for a sacrificial piece of ¼” board with cardboard torn from a Dr Pepper box as an additive spacer. Strapping tape was used to hold the board roughly in place and level before the pivot pin was added, but there was no damage caused by the adhesive. The back of the Q2 cabinet is covered with a textured, black vinyl “veneer” that atop the particle board construction raised concerns of possible chipping of the edge by the router bit. Standard doctrine and common sense called for masking tape to be placed over the surface to minimize this chipping, though at the cost of ease in moving the router bit – oddly, the tape hindered the movement of the bit more than nearly ½” of wood did. The work took longer than expected, but the results were excellent with a perfect fit for the grill (7 5/16”).

http://i30.photobucket.com/albums/c301/jpvanson/Q2%20Mirror-Imaging/6.jpg

The cutout looks especially large in this picture thanks to the light material, but it is the same size as that for the midbass coupler transmission line opening.

With the end of the day and the realization that I had forgotten to pick up black paint to match the original cutout and for aesthetic reasons, the rear EMIT and grill hasn’t been placed yet. Soon, though, I will finish up these minor details, repair the crossover, the damage in behind the grill supports (there is evidence that the cabinet fell on its face sometime in the past, driving the dowels back through the cabinet wall inside), and the drivers will be installed.

When everything is back together and working, I hope to post the results of the Quantum 2/AR-9 shoot out in the Speaker forum. After refinishing, more pictures will arrive here as well as my assessment as to whether the effort/expense in securing a cabinet and modifying it to suit was worth it. My preliminary impression is that the imaging is already much improved with less smearing at the higher frequencies.

- JP

[Army]

Awesome story JP!

Kudo's to jguzman and brainsmasher for pony expressing that cab to you :thmbsp:

As for the shoot out, you could do it in the speaker forum or here!

If you do it in the speaker forum throw a link our way, just for kicks!

I'd be curious as hell to see the your opinions and conclusions, since I like AR's as well :thmbsp:

[Charivari]

Thanks Army. I'll definitely make sure to post a link to the results here.

I just realize that I neglected a little bit of minor information. Those with astute eyes may have noticed that neither of the cabinets shown have their phase rings. It turns out that my early Q2s have much thicker phase rings than the later version, so I had to carefully cut each loose with a knife (siliconed into place). I am going to have to reinstall the old version on the new cabinet to ensure that each cabinet matches.

This is how significant the difference is:
http://i30.photobucket.com/albums/c301/jpvanson/Q2%20Mirror-Imaging/Q2a7.jpg

- JP

[Vitopanch]

Jp,
That was a great story. I especally liked the way that you laid it out. So glad that you were able to find another cabinet for this project. Restoring and maintaining those beatuies to an imaged pair is great. I too am very interested in hearing more about the shootout and the imaging improvement. I like AR's too.
Vito

[Kencat]

JP,

That is one heck of a project. Pretty cool.

The serial of the new box is very close to mine, approx 400 earlier. From what I could see of the xover in your pic it looked the same as mine.

About the crossovers.....what are the differences between the two boxes? The old box layout is way different from what I see in your pictues. The difference in the woofer phase rings may be (most likely are) reflected in the crossover design and values of R,C and L, to compensate for the different phasing in the woofer position.

I'm thinking that because your original speakers (serial numbers) are so....Uh..."unique", that to match the two mirror image boxes, you need to have the same phase rings and their respective crossovers to have each box properly mated.

The possible unknown though, is whether that thicker phase ring is required for the rear firing emit. That would mean your "new" box would need a crossover like your "old" box.

:yikes: does that all make any sense?

[Charivari]

Thanks for the kind comments, Vitopanch.

About the crossovers.....what are the differences between the two boxes?
The values are the same, just the capacitors are different as is the layout. My early Quantum 2s have the board on the bottom just like the layout documents show to be the case for the QLS-1.
I'm thinking that because your original speakers (serial numbers) are so....Uh..."unique"...
Fortunately, my friend brought his digital camera along, so I was able to snag a bunch of photos I have previously been unable to obtain. So, here are the pictures of the crossover plates showing the authenticity of the serial numbers. The sticker and text font are a match for what's on the other cabinet. Sometimes it's fun to be unique, but other times I get worried about why my serials are so different -- with the others, the first number indicates the model, Quantum 2 being "7", so what's up with that?

http://i30.photobucket.com/albums/c301/jpvanson/Infinity%20Quantum%202/Q2b2.jpg

http://i30.photobucket.com/albums/c301/jpvanson/Infinity%20Quantum%202/Q2a2.jpg

The possible unknown though, is whether that thicker phase ring is required for the rear firing emit. That would mean your "new" box would need a crossover like your "old" box.
The phase ring is intended to bring the woofer cone in line with the remainder of the drivers. However, the cone is, um, cone shaped, so the "in-line" Infinity had in mind was the median distance of the surface area that does the radiating or a tough deeper than half the cone depth. Thiel does the same thing by having the baffle sloped back instead and chooses to align the motors [VC and magnet] rather than the radiating surfaces to achieve phase coherence. Speaking of Thiel, a first order crossover is supposed to maintain phase and time alignment if properly implemented. So, by physically aligning the drivers and using this basic principle of crossover design along with a few other little additions, Infinity managed to keep align the phase and time of the drivers creating a coherent wavefront ... as we've discussed in the past. As the 12" Watkins has remained relatively the same driver outside of a few advances like poly cones over paper and the addition of a servo sensor on the TOTL models, the distance needed for phase alignment should be the same. Thus, the phase ring should be the same thickness regardless of the model or, the corollary, a shallower cone driver would call for the thinner phase ring. Why the change then? Good question and I've no clue. Maybe, just maybe, the designers decided to choose a different center line for phase alignment closer to the forward edge of the cone thus calling for less correction (ie, thinner ring).

As to the rear EMIT, considering this and that the Watkins is crossed out at 200 Hz, that shouldn't have any effect. The crossovers are identical between the two (rear EMIT and no rear EMIT) as far as I have seen thus far, though I've not torn the new crossover apart yet. The rear is just wired so that one wire (solid green) is connected to where the blue with stripe wire of the front EMITs connect to the up-leg side of the capacitor and the green with stripe connects to the solid blue right where the EMIT leads come out of the baffle and connect to the bottom front EMIT. That is a funny way to wire the rear EMIT when it could be done at the crossover completely, afaict, but with inverted phase to create the dipole effect.

Either way, I'm definitely keeping the same thickness phase rings because, um, I only have one thin version and I would need two. That and I like the look better (and prefer the technical reasons behind it, from what I've guessed).

About the crossovers.....what are the differences between the two boxes?
As to the crossover differences, well, will a couple of pictures showing the difference be good?

Early Q2 crossover with inductors bread-boarded onto the bottom of the cabinet:
http://i30.photobucket.com/albums/c301/jpvanson/Infinity%20Quantum%202/Q2a3.jpg

The midrange components are missing due to the previous owner's hack-job --to be repaired. That also has a lot to do with why there's such a nasty tangle of wires -- there's evidence they used to be tie wrapped together for a cleaner install. The black objects on the bottom are the Callins electrolytics stacked to reach the needed value for the Watkins. This is even different compared to the other Q2 of mine with different brand of original caps; the design was changing quickly back then.


Newer style Q2 crossover (like yours)"
http://i30.photobucket.com/albums/c301/jpvanson/Infinity%20Quantum%202/Q2c2.jpg
Notice the cap stack has been replaced with single cans.

- JP

[Kegger]

Very cool JP!

I'd love to hear and see those! The xovers look to have some pretty darn nice parts
installed there and obviously a lot of thought went into it.

[Kencat]

JP,

Your new box xover is VERY close to mine.....but wouldn't you know there had to be a difference :yes: Just for fun here are the comparo pics. Silver electro in place of your black one.

Kencats: (pot missing out for repair)
http://audiokarma.org/forums/attachment.php?attachmentid=12005&stc=1

Charivaris:
http://audiokarma.org/forums/attachment.php?attachmentid=12006&stc=1

Question: the midbass coupler - how is it connected to the port at the back? straight closed tube from front to back? or is it a convoluted tube? or ?????

Regarding the phasing - with the tweeters and mid-bass coupler wired out of phase with the woofer and the midrange, there is more going on here than simple physical alignment of the drivers. Because the crossover circuits ARE all 1st order (this I am sure about now after looking at more articles), there is no excuse to reverse the driver phasing due to a higher order filter. So Infinity is playing with phasing/timing of the drivers big time.

I still think that mid-bass coupler is out of phase to utilize it's rearward port (need to find more info on this), perhaps to bounce waves off of the back wall, which would make these Q2's somewhat sensitive to placement, as well as the rear firing tweeters adding to that some more on yours JP. Be careful in the shootout to play with the placement somewhat, as they could be at a big disadvantage if not set-up well (that'll be my story and I'm sticking to it :D ).

The woofer rings are interesting. I guess the engineers had a rethink of where the woofer should be at some point in the production. If you mount those rings so they are removeable, and you get another short ring :yes: you could speriment a bit to see which sounds better.

That ring thickness should be a design feature tracked in the database that no-one wants to contribute to (delete ?).

[Kencat]

JP,

How's the Mirror Image Project doing?

[Charivari]

Your new box xover is VERY close to mine.....but wouldn't you know there had to be a difference Just for fun here are the comparo pics. Silver electro in place of your black one.
Doesn’t surprise me. Even my older Q2s that are only one sn off have different caps in the crossover. The design appears to have been changing wildly back then and subject to parts availability. Oh, I can’t see your pictures for some reason.

Question: the midbass coupler - how is it connected to the port at the back? straight closed tube from front to back? or is it a convoluted tube? or ?????
The tube is a straight chunk of 5” diameter cardboard with some fiberglass stuffing in the older variant and polyfill in the new. It’s a most basic transmission line being without a taper and the stuffing makes the driver see it as being longer than it really is.

Regarding the phasing - with the tweeters and mid-bass coupler wired out of phase with the woofer and the midrange, there is more going on here than simple physical alignment of the drivers. Because the crossover circuits ARE all 1st order (this I am sure about now after looking at more articles), there is no excuse to reverse the driver phasing due to a higher order filter. So Infinity is playing with phasing/timing of the drivers big time.
Dunno what is happening, though, as I’ve said before, I’ve no doubt that all the drivers are in phase despite the wiring (which appears to be accurate in the schematic with a quick glance). These just don’t have the funky, pseudo-imaging enhancement that speakers like Wilsons with their reverse phase mids have. The Infinities sound good and right, not with the messed up sound of the others.

I still think that mid-bass coupler is out of phase to utilize it's rearward port (need to find more info on this), perhaps to bounce waves off of the back wall, which would make these Q2's somewhat sensitive to placement, as well as the rear firing tweeters adding to that some more on yours JP. Be careful in the shootout to play with the placement somewhat, as they could be at a big disadvantage if not set-up well (that'll be my story and I'm sticking to it ).
Perhaps, but I’m still extremely doubtful. At any rate, the placement will be more critical with the woofer to prevent bass boom or the like than it is with the rear firing EMIT. The shoot-out will definitely be fun and interesting. From what I heard, I do believe the Infinities have much superior bass if fed with sufficient power and superior highs than the AR-9s, but the ARs might still win out for midrange/midbass smoothness/body and possibly imaging thanks to the driver arrangement if given room to breathe.

The woofer rings are interesting. I guess the engineers had a rethink of where the woofer should be at some point in the production. If you mount those rings so they are removeable, and you get another short ring you could speriment a bit to see which sounds better.
Could, but until I have a larger room and much more power to play with, I doubt the phase ring will have a hearable effect past the other limitations. The deeper phase ring makes better sense to me, anyways, so I’ll stick with it.

That ring thickness should be a design feature tracked in the database that no-one wants to contribute to (delete ?).
I think it’s a sufficiently important feature to track in the database. As to contributions, I didn’t post in your thread as I didn’t want to clutter it. That is to say, I thought you intended to just post your data there.

How's the Mirror Image Project doing?
I was out of town for the week, so no progress has been made. Though, my new polys for the midranges have come in. No resistors yet.

- JP

[Negotiableterms]

JP-

Wow...great work so far!

You should go into business, and I should send you my QLSs as your first project. You can become the EW of Infinity Speakers.

[Charivari]

Thanks, David. That's a fun idea. Getting to repair all manner of good, vintage Infinities and giving 'em a listen before return. Dunno if the quality of my repairs would justify the cost of shipment, though.

- JP

[Kencat]

Oh, I can’t see your pictures for some reason. - JP

I noticed that too. :scratch2: I'll try an edit to put them back in


The tube is a straight chunk of 5” diameter cardboard with some fiberglass stuffing in the older variant and polyfill in the new. It’s a most basic transmission line being without a taper and the stuffing makes the driver see it as being longer than it really is. - JP

Hum, I always thought a transmission line was quite long. But then comparing the volume allowed on other "sealed" mid-range drivers, that tube is considerably larger, although being open to atmosphere as it is, it wouldn't compare to the sealed types. There must be some some really neat theory behind that design. I'll just have to trust that someone knew what they doing and enjoy the music.
:D

I think it’s a sufficiently important feature to track in the database. As to contributions, I didn’t post in your thread as I didn’t want to clutter it. That is to say, I thought you intended to just post your data there. - JP

No no, that's not what I meant. I wasn't expecting you to post anything as your data is already there. I'll add the ring depth to the one main post that is collecting all the data. No problem there :thmbsp:

What I meant is, there isn't anyone else writing in with serials etc., and this could just be that there are very few us with Quantums. Also, some people may prefer to stay anonymous. This database, while a neat idea, may not blossum into much. We'll see.

[Kencat]

Thanks, David. That's a fun idea. Getting to repair all manner of good, vintage Infinities and giving 'em a listen before return. Dunno if the quality of my repairs would justify the cost of shipment, though.

- JP

You could do housecalls :yes:

Dr. Infinity. Has a nice ring to it don't you think?

[Negotiableterms]

Dr. Infinity. Has a nice ring to it don't you think?

I'm imagining Dr. Who stepping in and out of a QLS instead of a phone booth. JP, can you do an English accent?

[Charivari]

You could do housecalls :yes:

Dr. Infinity. Has a nice ring to it don't you think?
There's an idea. A round-trip plane ticket would probably be cheaper than shipping some of the larger models.
I'm imagining Dr. Who stepping in and out of a QLS instead of a phone booth. JP, can you do an English accent?
'Fraid not, best I can do is either a Washington-Montanan blend for a clean dialect or some good ol' Warshintonian of the Willapa Hills flavor (Washington's version of Appalachia where there are towns with 80%+ of the population being related). I'm ashamed to admit that I've never seen a Dr Who episode, old or new, but I am aware of enough to know that I'd really like that dimensional technology to allow for more space in my apartment in the same footprint.

Oddly enough, I dreamt last night about doing such Infinity repairs as a means to aid in paying for parts for my own interest in the hobby. Though, quite good it ended poorly with an IRS V mid/tweeter tower falling onto me and pinning me down. :sigh:

- JP

[Vitopanch]

Oddly enough, I dreamt last night about doing such Infinity repairs as a means to aid in paying for parts for my own interest in the hobby. Though, quite good it ended poorly with an IRS V mid/tweeter tower falling onto me and pinning me down. :sigh:

- JP


HA HA HA HA

[Vitopanch]

What I meant is, there isn't anyone else writing in with serials etc., and this could just be that there are very few us with Quantums. Also, some people may prefer to stay anonymous. This database, while a neat idea, may not blossum into much. We'll see.

If I had a Quantum, which I hope to soon, I would certainly participate. I think that it is an interesting project and just needs to grow as our forum does. There is a huge amount of folk out there that is not even aware of this web site, nevermind the forum. There is nothing like this forum, as we know, on the internet, except the German one, which, must need finger printing or something before you can post on. As more folks learn about this some of them will be Quantum owners and like the database. I say keep it going because it adds an additional flavor to what is offered here. It will grow I think.
Vito

[Kencat]

If I had a Quantum, which I hope to soon, I would certainly participate. I think that it is an interesting project and just needs to grow as our forum does. There is a huge amount of folk out there that is not even aware of this web site, nevermind the forum. There is nothing like this forum, as we know, on the internet, except the German one, which, must need finger printing or something before you can post on. As more folks learn about this some of them will be Quantum owners and like the database. I say keep it going because it adds an additional flavor to what is offered here. It will grow I think.
Vito

Thanks for the encouragement Vito. It's not doing any harm sitting there, and we can work on it as need be.

:scratch2: I'll have to check out that German site just for interest...fingerprinted....that's good :lmao:

[Charivari]

Just a slight update, most of the parts I needed came in yesterday, the important stuff such as resistors anyways, so I was able to rebuild the hacked midbass and midrange sections of the one Q2 and the bad resistor in the other. By the time I finished cutting out the odd resistor ladders, stacked caps, and over-abundant silicone holding everything together it was too late to listen very much to the Q2s and at any volume. However, I have noticed that the newer cabinet is much brighter than the older even after replaced bad parts. Interesting, I can't figure out why that would be the case unless the older caps have somehow made for a thinner sound or the older variant that I like the warmer sound of better is suffering from bad caps on the tweeters. I did have to replace the 20.4µF cap or rather non-existent cap on the midrange with a 20µF Aerovox polyprop (0.4µF bypass cap waiting to ship) on the older speaker as well as the missing resistors with the 8.1Ω becoming 8.2Ω due to supply. Yet, I made some changes in the other as well .. ah well, if I have time later today, I'll go ahead and make the same changes between the two and see what comes of it. If the bypass caps ever come in so I can redo the tweeter caps, I'll know for sure.

- JP

[SicMan]

HI JP>
Still at it LOL! lots of work hope you enjoy the results...
buy the way you could send thos Q2's to me if you don't like them anymore :yes: I guess not though huh :no: just kidding.

Good luck.

John

[Army]

HI JP>
Still at it LOL! lots of work hope you enjoy the results...
buy the way you could send thos Q2's to me if you don't like them anymore :yes: I guess not though huh :no: just kidding.

Good luck.

John

Hey now the forum Mods have first dibs on any gear members get tired of :D

[Charivari]

Well, yeah, it takes a while to do such work thanks to the need to spread cost out and shipping time. Still, I'm not going to let my $15 Goodwill Infinities go, they've too much possibility. If I don't like the sound after repairs, then I'll start modding. Yep, I'll keep 'em, if only to keep Army from getting dibs on them.

- JP

[Army]

Yep, I'll keep 'em, if only to keep Army from getting dibs on them.

- JP



:lmao:

[SicMan]

They can keep my other ones company if I can find some room... :sigh:

[Charivari]

Fwiw, I think I've figured out most of the problem. Last night, I rebuilt the crossover in the newer cabinet with twin new components to what I used in the other -- resistors, new midrange cap, etc. It appears that the old 20.4µF TI had drifted far out of spec (resistors too, the 8.1Ω measured to over 10Ω on my Simpson -- so much for 10% tolerance) creating the lower midrange hole I was hearing and causing a thinner sound. Oddly, this speaker had been measuring 7dB louder with the controls flat than the other, but after new components is now only 1.5-2dB louder -- a mismatch that should be cured with new caps on the tweeters and, more importantly, the midbass. Overall, both speakers after partial repair are much brighter without the dark, rich tone they used to have. New caps on the tweeters might help that, much as they did with the midrange. If I can figure out a way to modify the one for biamping without drilling into the connection plate (want to keep it original seeing how mine appear to be very early examples of the model), I'll try putting a tube amp on the midbass/midrange/treble and see if that sweetens the sound. It should seeing how Arnie Nudell designed his speakers specifically for use with tube amps (though with solid state on the Watkins).


Sicman, do you run all of those at once? Mighty impressive looking collection you have there, though it looks like you don't have the Watkins woofers for yor Q3s. About a year ago, I found a guy in Seattle willing to sell me a set of Q3s for $50. I planned on literally stacking them with my Q2s, but he flaked at the very last minute saying that he had thrown them away and had forgotten. :dunno: You should try your Q3s in a 4.0 surround system for the Pink Floyd quadraphonic recordings or movies, I sure would if I were so fortunate as to have all those Quantums.

- JP

[Kencat]

JP,

Is it possible that by freshening up only a partial pallete of components, that the remaining old electronics are now out of balance with the new ones? hence the increased emphasis in the higher range.

If all the components in the crossover were replaced, perhaps it would all balance out and remain neutral. (those big caps would be a hit in the pockets though wouldn't they? ouch :sigh: )

Just some uninformed thoughts. Hope you can get them back to the way you like, although maybe they are sounding like they used to when new? Uh oh.....

[SicMan]

Well .... The room needs a little "re-org" the wife says. But the ones in the back are true 100% Infinity speakers, the front Q3's have the wrong subs and the Q5's as you seen in the other pics are missing the subs also. The back speakers work 100% and are the ones I bought in 1979 and just finished fixing them. I'm in contact with a few people that have them but may not give them up.
Yes! I do run all my speakers at the same time, I love a room full of sound. Since I got the 2 KR9600's and the SX-1250 they really sound awsome even in cripple mode. Of coarse I have severe hearing damage, and drain bamage also. :yes:

http://uspug.com/E/Chainsaw.gif

[Charivari]

JP,

Is it possible that by freshening up only a partial pallete of components, that the remaining old electronics are now out of balance with the new ones? hence the increased emphasis in the higher range.
I do believe that was the large part of it. Now that both crossovers match, the sound is better. Still can't figure out why the same drivers and parts still result in one being "louder" than the other.

If all the components in the crossover were replaced, perhaps it would all balance out and remain neutral. (those big caps would be a hit in the pockets though wouldn't they? ouch :sigh: )
I hope so, but I'm waiting on some more caps for the tweeters before I can change those out. The caps on the Watkins, well, they're going to have to wait. With any luck, everything will end up neutral sounding. Already, they're sounding better, but whether it's the caps breaking in or the speakers breaking my ears in (likely the latter) remains to be seen.


Sicman, I can definitely understand how much fun a stack of good speakers can be. Sure, the sound won't be audiophile and have no imaging, but the result can just simply rock. When you manage to find the proper woofers for the rest of the Infinities, I'd start worrying about structural damage, though.

- JP

[Kencat]

I do believe that was the large part of it. Now that both crossovers match, the sound is better. Still can't figure out why the same drivers and parts still result in one being "louder" than the other.

- JP

Check that the wiring to the drivers is the same. With the reverse phasing on the mid-bass and the tweeters, if one or both drivers in a speaker was connected + to + instead of + to -, it may increase the volume, .....or it may decrease it.....hard to predict that one. :scratch2:

It's something to check.

[Charivari]

Check that the wiring to the drivers is the same. With the reverse phasing on the mid-bass and the tweeters, if one or both drivers in a speaker was connected + to + instead of + to -, it may increase the volume, .....or it may decrease it.....hard to predict that one. :scratch2:

It's something to check.
Dang, you're good. I just checked and guess what? The schematic is wrong. I connected the midbass on the newer cabinet just as the schematic has it. However, when I cracked open the midbass on the older cabinet, the connections were bass ackwards. The yellow/black wire goes to the positive terminal as denoted by the red sticker and the yellow to the neg, opposite of the schematic, which is why it looked correct when I looked at the crossover -- the midbass's pos is connected with the color scheme for neg on all the other drivers. This just goes to show why you can't trust schematics exclusively and why I should've paid more attention when swapping drivers over.

Now, the Q2s are playing and sounding much better, the levels match to at least within 0.5dB between the speakers and there is no longer the midbass/lower midrange suckout that was bothering me so. Unfortunately, I've lost some of the gimmicky imaging that was giving me sounds several feet to the sides of the speakers with certain tracks on Tuatara - The Loading Program, but I've also lost having the soundstage three inches from my face. Guess I'll have to just enjoy my good, accurate speakers rather than the Wilson clones I had for a bit.

Thanks for the suggestion that I should not have overlooked.
- JP

[Negotiableterms]

...I just checked and guess what? The schematic is wrong.

On my original set of IRS Betas, one of the four woofers in one tower was wired backwards. I was never entirely happy with their bass until I had them refoamed (in my home) and the tech pointed out the error. Switched the leads and presto! Great bass!

The point is that Infinity was not immune to assembly errors.

[Charivari]

The point is that Infinity was not immune to assembly errors.
No argument there. However, schematics are notorious for being wrong as well, be it with changed component values to misdrawn wiring diagrams. I am quite certain that the problem lies with the schematic. Connecting the midbass according to the schematic results in a very unbalanced sound with almost no lower midrange/midbass and weird phasing effects near the crossover boundary when running frequency sweeps. The inverted connection of the driver had in the recent past caused Kencat and I quite some confusion as there was no logical explanation for why it would be connected 180° out of phase. To my ears, the speakers sound right with the driver connected opposite the schematic the other way sounded very off, hence my prior mentions of there being a problem.

Of course, I'll keep an open mind being that I've only had a couple of hours experience with the return to the "original" wiring scheme (before I changed it to match the schematic) after the crossover repairs and maybe I'll find that the midbass changes wildly when I move the speakers. Should other Q2 owners pull their midbass drivers and look for themselves and if they find the schematic to be accurate, then I'll recommend switching the wires as a very worthwhile upgrade.

Addendum: I've just finished running some test tones, again, both ways on both speakers together and just the newer one alone. It definitely sounds off when the midbass is wired up according to the schematic, very incoherent with an obvious mismatch at the crossover frequency (200Hz) between woofer and midbass. However, I've also learned another reason why the newer Q2 still sounds louder -- the older rolls its EMITs off severely above 12kHz whereas the newer continues on up. Guess I'll have to hurry up on replacing those caps. At least I've proven to myself that I can still "hear" 20kHz, which surprises me, though at greatly reduced levels.

- JP

[Kencat]

Dang, you're good. JP

:sigh: Well not really...I wasn't expecting to hear that the schematic is wrong :headscrat

I just checked and guess what? The schematic is wrong. I connected the midbass on the newer cabinet just as the schematic has it. However, when I cracked open the midbass on the older cabinet, the connections were bass ackwards. The yellow/black wire goes to the positive terminal as denoted by the red sticker and the yellow to the neg, opposite of the schematic, which is why it looked correct when I looked at the crossover -- the midbass's pos is connected with the color scheme for neg on all the other drivers. This just goes to show why you can't trust schematics exclusively and why I should've paid more attention when swapping drivers over.

- JP

I'll dive into mine JP, and find out what the wiring is doing compared to the schematic. I find it hard to believe this would be the case, but, hey, you never know. With your old ones though, I wonder if the wiring could have been different to the later versions, especially given that the phase ring is different and the extra rear Emit being in place.

What about the tweeters? Are they not phase reversed either?

Very interesting turn of events eh? This'll create some work and discussion for sure :D

[Charivari]

:sigh: Well not really...I wasn't expecting to hear that the schematic is wrong :headscrat

I'll dive into mine JP, and find out what the wiring is doing compared to the schematic. I find it hard to believe this would be the case, but, hey, you never know. With your old ones though, I wonder if the wiring could have been different to the later versions, especially given that the phase ring is different and the extra rear Emit being in place.

It doesn't surprise me. I literally grew up in my father's marine electronics repair shop where instead of a bassinet, I had a radar box. So too did I spend much of my childhood working with him on the fishing boats when not in school. What I learned through this experience is that schematics are wrong far more often than one would like to hear and inaccuracy tends more to be the rule than the exception. Wiring diagrams have one or two connections drawn wrong, parts on the board aren't in the schematic and vice versa, and other parts are updated in the unit but not the schematic. I recall one instance where my father discovered an issue with a schematic for a radar that showed an expensive board (many ICs and designed so the entire board is replaced rather than defective parts) connected to power with the incorrect polarity. To have changed the unit to match the schematic would've resulted in a few hundred dollars worth of repair parts and work. When he (my father) called the manufacturer rep to inform them about this important issue, he learned that the manu. didn't publish their own schematics/service manuals but hired another company to do it.

So, needless to say, I don't revere schematics/service manuals/etc as infallible. My ears tell me that the midbass does not sound right when connected as specified in the PDF crossover schematic file -- that just so happened to have been put together a few decades after the speakers were built, possibly from incomplete records.

I am curious, though, as to what you'll discover. I don't think the drivers were mysteriously changed.

What about the tweeters? Are they not phase reversed either?

Very interesting turn of events eh? This'll create some work and discussion for sure :D
Working on these one step at a time. I've not looked closely at the tweeter phase issues yet, aside from recognizing that the rear EMIT is connected opposite the front EMITs. I dun think the roll-off I'm hearing is related to that seeing how phase issues should come in to play lower in frequency and lessen higher up due to the wavelengths involved. Still, I'll probably dig into these some more later today. This was an interesting turn of events, but not too surprising seeing how odd my pair of Q2s appear to be. Wonder why I always seem to end up with the oddballs?

- JP

[Kencat]

JP et al,

Well, hate to say it, but........... my Q2's are wired per the schematic. The solid yellow wire is attached to the midbass driver terminal with the red dot. The solid yellow wire traces through the crossover through the capacitor and inductor, to the negative speaker wire leads.

The Tweeters also are wired out of phase as per the schematic, with the solid blue wire on the tweeter + terminal and the wiring tracing through to the negative (-) speaker wire leads.

Pic of midbass below with solid yellow on the + (Red Dot) terminal.

http://audiokarma.org/forums/attachment.php?attachmentid=12904&stc=1


As a result of being forced to tear apart my Q2 speaker in the interest of science and good for all Infinitoids, I found a possibly significant defect in my midbass driver sono tube....a big honkin unplugged hole. See pic below. This would be venting that wonderful Watkins to the atmosphere through the bazooka-sized midbass tube.


http://audiokarma.org/forums/attachment.php?attachmentid=12905&stc=1


She's now plugged :thmbsp: Now, let's hope this is not an important design feature necessary to keeping the woofer from self destructing due to excessive internal pressure. Any opinions on this before I do something to my speakers ????? :D

[Charivari]

On all three of my Q2s, the single hole for the midbass wires was right up near the baffle (your open hole) and plugged with a wad of grey clay. Either yours was a 5PM Friday afternoon special or someone's been messing around with yours. Be sure the hole's plugged on both as any leaks with these speakers will mean a loss of low-end and "huffing" at volume.

As to the discrepancy, well, for the time being, I'll stick with the full-range, well-integrated sound I get with the midbass being wired "wrongly" over the Bose Acoustimass sonics (subwoofer w/ cheap sats and a huge gap in between) I was getting before with speaker wired as per the schematic. Might I suggest swapping the wires and find out how yours sound that way?

Which reminds me, have you listened to yours yet or are you still waiting on some parts?
- JP

[Charivari]

If you want to compare drivers to see if there's a difference there (unlikely, imho) the numbers off the back of the magnet are as follows:

AD 5060/W8
2422 257 35302
01 02 703 94
Made in Belgium

Lots of useless numbers there, but, eh.

- JP

[Kencat]

As to the discrepancy, well, for the time being, I'll stick with the full-range, well-integrated sound I get with the midbass being wired "wrongly" over the Bose Acoustimass sonics (subwoofer w/ cheap sats and a huge gap in between) I was getting before with speaker wired as per the schematic. Might I suggest swapping the wires and find out how yours sound that way?

Which reminds me, have you listened to yours yet or are you still waiting on some parts?
- JP

I will keep the wire swapping in mind JP. Will need to spend some time with them as is for a while first.

As far as listening to them....well, I'm listening to one right now. I got the cleaned up pots resoldered in today. These were the speaker that I replaced the tweeter diaphragm in and everything else is working ok. I've got Winamp set to mono, and have the Adcom set up so power should not be an issue.

I had the speaker pretty far out into the room, and was a little surprised at the lack of bass. The mid to high range is superb. I figure the woofer needs some break in time (new refoam) as well as the caps (probably haven't been run in a long time). However, I just pushed the speaker back up against a wall (one foot away) and the bass is way more pronounced.....nice :D

I was sitting at the back of the speaker for a while, and cannot believe the amount of sound coming from the midbass port. It is almost fullrange back there. This just reinforces in my mind that the back port is pumping some significant sound rearward, that has to be reflected back into the room. The phasing of this reflected sound is going to be dependent on speaker placement. The reverse phasing of the driver has to be deliberate to take into account reflection from a back wall.

The difference I just heard in moving the one speaker is incredible. Closer to the wall is much nicer. I just moved it in closer. I am feeling bass in my body now...incredible. Setting up two of these is going to be a Taguchi experiment nightmare.

Tomorrow I solder in the new resistor ( wanted two but one is back ordered) in the other speaker and I'll get that one working to try em out in stereo (can't wait).

As far as volume goes...man...more than I need in my little room. This isn't even beginning to use the Adcom, I don't think anyways. The preamp is only three clicks from zero and it's loud enough thank you very much.

Enough rambling. Done.

[Charivari]

I had the speaker pretty far out into the room, and was a little surprised at the lack of bass. The mid to high range is superb. I figure the woofer needs some break in time (new refoam) as well as the caps (probably haven't been run in a long time). However, I just pushed the speaker back up against a wall (one foot away) and the bass is way more pronounced.....nice :D
What you're hearing with the Watkins bass (sub-200Hz) is the break-in of the foam, but more importantly a much more accurate, flatter bass than typical. Too many speakers have a slight hump down low around 50Hz for the "wow" factor and to give the impression of deeper bass. The Watkins, on the other hand, has no hump. So, you won't notice a lot of bass, but when there is real, low bass in the music you're playing, you'll definitely notice in a hurry.

I was sitting at the back of the speaker for a while, and cannot believe the amount of sound coming from the midbass port. It is almost fullrange back there. This just reinforces in my mind that the back port is pumping some significant sound rearward, that has to be reflected back into the room. The phasing of this reflected sound is going to be dependent on speaker placement. The reverse phasing of the driver has to be deliberate to take into account reflection from a back wall.

The difference I just heard in moving the one speaker is incredible. Closer to the wall is much nicer. I just moved it in closer. I am feeling bass in my body now...incredible. Setting up two of these is going to be a Taguchi experiment nightmare.
The midbass only runs from 200Hz to 600Hz, not accounting the roll-off at the crossover points that still means a fair bit of output to an octave or so on either side. So, it doesn't surprise me how much you're hearing out the back. However, this is a fairly important frequency spectrum encompassing a fair number of instruments and male vocals. My experience with another rear firing speaker that runs up high -- the Design Acoustics D-6 -- has shown that such an arrangement is very, very sensitive to positioning particularly so when you're trying to avoid a frequency hole with the reflected sound. To be honest, except for the rare room, relying on reflected sound is sonic dead end when it comes to good audio. I really think that you should try flipping the wires on the midbass and see how you like the sound. I think you'll much prefer the result as well as avoid the issues of frustrating placement and reflected chaos.


Tomorrow I solder in the new resistor ( wanted two but one is back ordered) in the other speaker and I'll get that one working to try em out in stereo (can't wait).
Good luck with that, be sure to report back with your impressions after you've had a chance to play around with them some.

As far as volume goes...man...more than I need in my little room. This isn't even beginning to use the Adcom, I don't think anyways. The preamp is only three clicks from zero and it's loud enough thank you very much.
Funny you should mention that, I'm enjoying a pair of 82dB/w/m @ 5 ohms Magnepans running off of a 15wpc 6BQ5 amp.

Well, the Infinities aren't that inefficient, just ~84dB/w/m at 4 ohms. :thmbsp: I've actually managed to run my pair off of a Sonic Impact T-amp for a test and yes, you can get reasonable volumes off of low power. However, as soon as the deep bass kicks in and I mean real deep bass (~20Hz, not that 40-60Hz stuff people call deep) you'll definitely recognize the need for enough power. If you have it, play Massive Attack - Mezzanine or any Telarc disk with drums and you'll hear what I mean -- the Watkins needs power for low bass and very much so for transients.

- JP

[Kencat]

If you want to compare drivers to see if there's a difference there (unlikely, imho) the numbers off the back of the magnet are as follows:

AD 5060/W8
2422 257 35302
01 02 703 94
Made in Belgium

Lots of useless numbers there, but, eh.

- JP

Check my post on the drivers. I had taken pics when I had the midbass out, thinking it would be good to post the ID numbers for others to see. Appreciate the thought though.... :thmbsp:

[Charivari]

Yesterday, I jury-rigged biamp capability into my older Q2 so I could experiment with running a tube amp on the midbass/midrange/EMITs with a solid-state amp on the Watkins woofer. While I was digging in there, I tried to locate the cause of the HF roll-off with the older cabinet. However, I was unable to find the cause and, frankly, am a bit stumped as to why it's still happening above 12kHz and drops off shortly after 16kHz.

The capacitors and resistors in both crossovers were replaced with identical units. The potentiometers for the EMITs were cleaned on both and measure the same. The wires feeding the EMITs that roll-off are in good shape without raised resistance. The EMITs in both units measure 0.5ohms in the system (5 paralleled) and each measures just a touch under 4 ohms (5.6 ohms on the rear EMIT as it should be) with a little variability between the drivers. The drivers in the newer cabinet were removed from one just one serial number different from those in the old cabinet. All told, both Q2s' EMITs and crossover components measure the same with no evidence of the solder issue Kencat noted in his thread made sticky. Yes, I've tried switching amplifier/source channels and the problem is with the speaker.

So, why are the EMITs in the older cabinet still rolling off early? Any ideas? As far as I can tell, there's no reason for the roll-off unless the problem lies entirely with the drivers themselves. So, to figure that part out, I'm going to swap drivers between the cabinets later today, but if anyone has any ideas, please chime in and let me know what I may be overlooking.

Thanks,
- JP

[Kencat]

JP,

:confused: 5 emits ? 3 front, one rear no?

Anyway, you've confirmed that the system DCR for each speaker set is the same. Check.

Wiring - are the 3 front Emits all wired in the same phase? If one emit was backwards it might do the roll off. Trace those wires closely.

How is the rear Emit wired? Directly to the crossover, or coming off of the front Emit set? If so, is the wire coming from the 1st Emit or the last one in the series? Is this the same between the old and new one.

Is the rear emit wired in phase with the fronts, or is there a switchero? Same between the two speakers?

Trace those wires from the speaker terminals on thru in detail, making a schematic as you go, so you can compare the two speakers. Might be a subtle (or not) difference somewhere.

The only other thing I can think of right now, if it is not wiring/electrical, is that there is a physical difference that is creating a filter effect. Depth of the recesses? or an unplugged hole from one of the recesses into the cabinet? :scratch2:

Good luck!

[Charivari]

4 EMITs. I took an unbelievably long time to get my brain going today and it still isn't fully running. So, bear with me. The rear EMIT is both connected to the front EMITs with one wire and the crossover with another. However, I connected my spare EMIT (the ~4ohm front variant, not the 5.6 ohm rear) as the rear EMIT on the newer cabinet until I can repair the other, so that shouldn't be the cause of the roll-off. Besides which, I was hearing the roll-off both ways with the rear EMITs connected and disconnected on both speakers. Besides which, I modeled the connection of the rear EMIT with the new cabinet on the old cabinet, so they're connected the same. The rolling off EMITs are actually those that I've not messed around with the wiring of and are connected the same way as the others with no crossed wires that I can see. Both sets of EMITs are angled the same way and are positioned in the same relative baffle position, so that shouldn't be causing issues.

As soon as I can overcome my reluctance to dig into that fibreglass filled older Q2 again (I hate itching despite the precautions I take), I'll go through all of it again and make sure one of my wires isn't crossed.

I'm definitely confuzled on this 'un. It should work, but isn't.

- JP

[Charivari]

Quick update:

I swapped the front EMITs and ran my frequency sweep again ... the problem didn't follow the drivers. Whew, I won't have to crack them open. Of course, this means I'll have the grand fun of digging through the fibreglass to find whatever's causing the problem.

Quick recap: Potentiometer is clean and good. Caps have been replaced and switch has been cleaned and set to the same position on both. EMITs are good and wired the same between the cabinets.

Here's the schematic, as you can see, there's not much to go wrong. So, its back to searching.

- JP

[Charivari]

So I might continue this fun discussion with myself, I have solved the problem. It was composed of three parts, two of which I am capable of fixing and have fixed. Turns out there was a cold solder joint down in the crossover treble section that had escaped resoldering during my rebuild. The second part had to do with a broken lead on my replacement 8.1ohm resistor for the midrange drivers, which though they still worked, caused some odd peaky behavior up near where the EMITs take over. The third part took me a little longer to figure out. It turns out that while my right ear can still hear out to 20kHz, though greatly depressed in response by then, while my left ear "rolls off" around 14kHz and is pretty much gone by 17kHz. It was this biological imbalance of which I was unawares that caused my need to troubleshoot further before I could be certain of it.

So, let that be a lesson to y'all, get your hearing checked with the fancy equipment that determines levels as well as frequency rather than the simplest version at most doctor's offices.

- JP

[Charivari]

How is the rear Emit wired? Directly to the crossover, or coming off of the front Emit set? If so, is the wire coming from the 1st Emit or the last one in the series? Is this the same between the old and new one.

Is the rear emit wired in phase with the fronts, or is there a switchero? Same between the two speakers?

Trace those wires from the speaker terminals on thru in detail, making a schematic as you go, so you can compare the two speakers. Might be a subtle (or not) difference somewhere.
I did modify my blown-up print out of the schematic as I went to reflect how all three cabinets (early and later versions) were wired up. I say modify because there are differences between how all three Q2s actually are and how the schematic is drawn up. With regards to the EMIT section, the differences are minor. The treble section of the crossover (potentiometer, freq. switch, and double bank of capacitors) is connected to the positive terminal, not the negative, but does so with the blue w/ black stripe wire -- the color coding used to denote negative polarity with the other drivers. The solid blue is subsequently connected to the negative terminal. Despite these differences, the front EMITs are connected out of phase (solid blue wire to pos. terminal on the drivers) with the three front EMITs being paralleled (solid blue wire and blue/black wires run up behind the drivers with little legs soldered on and directed to the terminals). The rear EMIT is connected out of phase with the solid green wire being connected to the blue/black positive EMIT lead via the spade strip below the crossover. The green/black negative lead is taken off of the bottom front EMIT's negative terminal, run back through the front hole, across the cabinet, and out the back to the rear EMIT. Interestingly, the inverted phase in the treble is consistent across the system.

I may try switching the treble polarity in the future as an experiment, seeing how great of an improvement was had doing so with the midbass, but at the wavelengths we're dealing with at and the number of reflections to be had beforehand, I do not believe the difference will be readily hearable. Then again, absolute polarity with the planar drivers could very well be different than with the conventional cones and domes.

- JP

[Kegger]

JP I'm glad you seem to be getting ahead on this project and the fact you've been able
to biamp with tubes with good results. Sorry to hear about your hearing but I bet we all
have issues by now and I'm sure it's not much if any hinderance anyway.

I use to work for a cassette tape duplicator and spent some time in the recording studio
both as a tech and sound engineer, we would have to get our hearing professional tested
every 6 months and at that time my hearing was solid upto 18K in both ears but I bet I've
got some issues now even though I can still here 16K tones being generated pretty easily.

Have you determined that your pretty sure the schem is wrong and that the mids need to
be wired in phase to work correctly? I would bet that is the case. A first order xover should
have all the drivers wired in phase and if you reverse them and get a suckout that is a test
that is performed to know for sure they are wired correctly, meaning if you get the suckout
when reversed then you know that the xover is correct when they are not reversed.

[Charivari]

No biggie on the hearing, I was actually surprised that I could hear out that far with the one ear. I spent too many years down in the engine rooms (cramped steel boxes with large, non-sound reduced diesels) of many tuna boats and other fishing vessels helping my father repair something or other to have much top range left in my hearing. So, to be able to hear out to 20kHz with even one ear was a very pleasant surprise. It is understandable, though, as I recall reading an article a few months ago that mentioned that everybody has one ear that hears better than the other and that it is typically that on the dominant side (right ear for right handed folks and left for left).

As to the schematic, I've determined that the schematic is wrong in several places to a sufficient degree that I am confident in this conclusion. Though, everyone else remains skeptical believing in the infallibility of schematics and possibly the easter bunny as well. I've listened to far too many test tones and frequency sweeps for the sake of my sanity and that of my neighbors. With the midbasses connected as per the schematic, there is a huge hole in the sound in and around the frequencies covered by the drivers. The result is an extremely thin sound that is reminiscent of the Bose Acoustimass systems that have a ~200Hz gap between the bass module and the satellites. When I reverse the phase of the drivers to match the rest of the system, the sound is what a speaker should sound like with a nice continuous sweep up the range without holes. Now, it could still be dependent upon my room, but I've moved these around a fair bit since discovering this issue and it certainly doesn't sound room dependant to my ears or SPL meter.

If you're curious, this is what the schematic looks like:
http://audiokarma.org/forums/attachment.php?attachmentid=4908
According to how my early pair is wired up (and partly with the newer cabinet) the midbass polarity is wrong and the EMIT connection is completely reversed as well.

- JP

[Kegger]

It's hard to say for sure with all those band passes going on for sure how it should
be wired without actually testing it but I would think all drivers wired in phase would
be the correct way to do it unless like you say you were going for some bose kinda
thing with frequencies all over the room but it would take the right room!

[Kencat]

As to the schematic, I've determined that the schematic is wrong in several places to a sufficient degree that I am confident in this conclusion. Though, everyone else remains skeptical believing in the infallibility of schematics and possibly the easter bunny as well.- JP

Ah now JP, you mean the Easter Bunny didn't pay you a visit last night? :D

As far as the schematic goes, I have written before as well about the definite reverse placement of the caps and potentiometer in the circuit, but they are at least accurate wrt the reverse phasing. There is a definite issue there.

I've listened to far too many test tones and frequency sweeps for the sake of my sanity and that of my neighbors. With the midbasses connected as per the schematic, there is a huge hole in the sound in and around the frequencies covered by the drivers. The result is an extremely thin sound that is reminiscent of the Bose Acoustimass systems that have a ~200Hz gap between the bass module and the satellites. When I reverse the phase of the drivers to match the rest of the system, the sound is what a speaker should sound like with a nice continuous sweep up the range without holes. Now, it could still be dependent upon my room, but I've moved these around a fair bit since discovering this issue and it certainly doesn't sound room dependant to my ears or SPL meter. - JP

I am leaning toward agreeing with you on the midbass. My rearrangements have helped with the sound, but I'm finding that boosting the 200 - 600 range on the equalizer is still more pleasing, BUT, that is so dependent on the music. Some like the boost but others don't :scratch2: This could just be my personal preference though, as I've always loved a more bass heavy sound. I probably am an East Coast sound type of guy. My cautiousness is just my nature to not get too radical before eliminating the simpler and more obvious solutions. I am probably going to try this polarity reversal sometime to see what it does ( I have to pop the bloody woofers though to feed the wires through the tube, as the midbasses will not pull out far enough to get hold of the wires :sigh:).

For my own interest - when you are checking with your SPL meter, is it registering the "hole" that you are hearing? If so, by how much, and is it a gradual curve or a sudden sharp dip?

It's too bad that no other Q2 or Q3 owners are chimimg in with their impressions. We need a larger sample size to determine if the wiring in other units match the schematic or not. Also, how could there be such good things always said about the quantums when they have been wired wrong? and actually sound quite crappy once compared with having this midbass region is boosted? I just checked the QLS schematics, and they also show the reverse phase midbass. If this hole existed in those TOTL models, wouldn't they have been crucified by the press? The Q3 schematic is also reverse phase wired. Errors in all schematics?

I really don't think mine have been monkeyed with (only one of the midbass tubes had the extra hole in it, and that could have been a factory goof.) Mine were bought from a one owner family in a very well-to-do Toronto neighborhood, not from a "reseller". There isn't really evidence of any rework or hacking in these. The pots were all actually in fantastic shape which means these have been kept in a superb environment most of their life. Also, the surrounds were rotted, so they were not tech-savvy enough to have known to replace these.

All the above really makes me believe the factory wired mine up this way (reverse polarity). It would really be nice to have a definitive (old Infinity employee) answer on what the original design criteria was.


According to how my early pair is wired up (and partly with the newer cabinet) the midbass polarity is wrong and the EMIT connection is completely reversed as well.

- JP

JP, I still have reservations about making this bold conclusion. We need more data from other Q owners. Three different schematics are wrong from Infinity?

The Emits, just to clarify your statement, are correct in that the front units are wired in reverse phase per the schematic. The only discrepency is the placement of the caps and pot on the the solid blue wires for the Q2. The QLS and Q3 schematics show the proper placement of this harware on the Blue/Black wires.

[Negotiableterms]

I vaguely recall that to test the phasing of drivers, all you need is a 9-volt battery and a magnifying glass.

You connect the battery negative to the negative of the speaker input, then just touch the battery positive. All the cones should jump forward. You use the magnifying glass to observe the tweeters etc. My recollection is that if the cones jump back, the speaker is out of absolute phase, and there will be some acoustic effect (dunno what). If the cones don't all jump the same way, there will be cancellation at the crossover points. If the two channels don't behave the same way, there will be big cancellation effect along the centerline between the channels, creating a dead spot instead of a sweet spot.

Now, I admit that this is a very simplistic, naive test, but assuming you're able to see all the drivers move, it's supposed to work. There's also a trick with a small strip of thin paper layed across the tweeters to visually amplify the movement.

Now, having writ this, GordonW, JP, Kencat or some other maven will explain why it only works some times, and not well, etc., etc.

[Kencat]

I vaguely recall that to test the phasing of drivers, all you need is a 9-volt battery and a magnifying glass.

You connect the battery negative to the negative of the speaker input, then just touch the battery positive. All the cones should jump forward. You use the magnifying glass to observe the tweeters etc. My recollection is that if the cones jump back, the speaker is out of absolute phase, and there will be some acoustic effect (dunno what). If the cones don't all jump the same way, there will be cancellation at the crossover points. If the two channels don't behave the same way, there will be big cancellation effect along the centerline between the channels, creating a dead spot instead of a sweet spot.

Now, I admit that this is a very simplistic, naive test, but assuming you're able to see all the drivers move, it's supposed to work. There's also a trick with a small strip of thin paper layed across the tweeters to visually amplify the movement.

Now, having writ this, GordonW, JP, Kencat or some other maven will explain why it only works some times, and not well, etc., etc.


NG,

I think the main point of interest in all this is whether the design of the midbass coupler was INTENTED by design to be wired out of phase with the woofer and mid-drivers, in the QLS, Q2, and Q3 speakers. All three schematics (as posted on www.infinity-classics.de) show this reverse phase layout.

My Q2s were received wired as such. JPs older (?) speakers were not wired per the schematics. JP believes that there is a hole created in the 200 - 600 Hz freq range when the midbass is wired reverse polarity, and that when wired in phase, the sound is much enhanced (this I do not dispute one iota, the question is whether Infinity wanted it to be so :scratch2: ). I am finding my Q2s ok as long as there is ample "air space" around the speakers and each one tucked in between the rear and side walls within 2' or less.

The unknown, I think, in all this, is the function of the rear-ported tube of the mid-bass coupler. If the mid-bass was a sealed unit, this would all be a no-brainer - out of phase no way Hose. But, the sound waves coming out of the back of the tube are stronger than what eminates from the front of the driver (my ears placed close to each at each location :yes: ), so it's possible there is a "Bosiesque" design intent here. We Quantum 1,2,3, owners NEED TO KNOW!!!!

NG - git those QLS's going buddy....we need to know more about the midbass suckout mystery. :D

OR, can you you dig into those puppies and determine how they are wired???? We nied moor data cawptain!!!

[Charivari]

As far as the schematic goes, I have written before as well about the definite reverse placement of the caps and potentiometer in the circuit, but they are at least accurate wrt the reverse phasing. There is a definite issue there.
My point in identifying those differences was to show that there are other errors in the schematics. If the labeling of the wires was switched then it takes no large leap of faith to think that perhaps they also switched the "+" and "-" on the midbass connection. On a different point, my early Q2s was lacking the 0.33uF bypass caps on the two positions for the tweeters with no evidence of their having ever been there. The newer cabinet did posseess these caps, though.
I am leaning toward agreeing with you on the midbass. My rearrangements have helped with the sound, but I'm finding that boosting the 200 - 600 range on the equalizer is still more pleasing, BUT, that is so dependent on the music. Some like the boost but others don't This could just be my personal preference though, as I've always loved a more bass heavy sound. I probably am an East Coast sound type of guy. My cautiousness is just my nature to not get too radical before eliminating the simpler and more obvious solutions. I am probably going to try this polarity reversal sometime to see what it does ( I have to pop the bloody woofers though to feed the wires through the tube, as the midbasses will not pull out far enough to get hold of the wires ).

Well, that sucks. On mine, the midbass wires, if anything, are too long. I can pull the driver and it’ll hang below the woofer. Most of the wires to the drivers inside are easily a foot and a half longer than need be and are doubled up to reduce the tangle somewhat. So, I suppose switching the wires isn’t so simple as removing 8 screws and swapping four wires.
As to East coast sound, I too am a fan of it, but the East coast sound isn’t excessive bass. You must be thinking of West Coast sound that is essentially defined by bloated midbass (~50-80Hz), no deep bass (sub-40Hz), and overly bright treble (typically 10dB above flat) all with high efficiency. Think Pioneer HPM-100, JBL, or Altec. East coast sound is more about tighter, flatter, and deeper bass that isn’t bloated, rolled off highs, and focus on the midrange.
As to radical changes, I just go by what my experience, knowledge, intuition, a goodly helping of common sense, and much observation reveals to me to be the right choice. So, what comes of it isn’t “radical” it’s simply the “better” way in my mind.

For my own interest - when you are checking with your SPL meter, is it registering the "hole" that you are hearing? If so, by how much, and is it a gradual curve or a sudden sharp dip?

The SPL meter does some funky stuff with the midbass connected out of phase. There are a few sudden, sharp dips and peaks around the crossover frequency and harmonics as I predicted, but it doesn’t measure a hole. This comes as no surprise because though the driver is out of phase, it’s still outputting sound. However, a pink noise mono signal shared between the speakers results in ~5-7dB more output with the woofer connected out of phase vs. in phase, but the sound is painfully thin (metaphorically speaking).


It's too bad that no other Q2 or Q3 owners are chimimg in with their impressions. We need a larger sample size to determine if the wiring in other units match the schematic or not. Also, how could there be such good things always said about the quantums when they have been wired wrong? and actually sound quite crappy once compared with having this midbass region is boosted? I just checked the QLS schematics, and they also show the reverse phase midbass. If this hole existed in those TOTL models, wouldn't they have been crucified by the press? The Q3 schematic is also reverse phase wired. Errors in all schematics?
Good question. Perhaps not all Quantums were wired according to the schematic, mine sure weren’t. Perhaps my room is really funky (which I already know it to be, but I’ve done a lot of repositioning without a change in the results). As to the press, well, no matter what they may think of themselves, their words are not gospel. Heck, a few of the golden children of the audio review world have praised the sound of speakers and gear that were later found to measure horribly and I do mean horribly bad and that others, outside of the press, found to sound terrible. So, as I said, I draw my own conclusions and stick by them until I find myself to be wrong rather than just follow along with what I’m told to think. Of course, this has drawn the ire of fanboys of other gear in the past, but so be it.


Negotiableterms, just a few minutes ago I tried to test what you said in your post. I’m afraid I don’t have a 9volt battery to test the speakers, though your thought is sound, and even then, I’m not certain that I could detect the miniscule movement of the midrange domes and especially the EMITs. However, playing a drum track with strong transients, I compared the midbass driver by sight and feel (fingers lightly touching the edge of both cones). I couldn’t crank up the volume thanks to the time and the return of my neighbors post-holiday, but I’m fairly certain that the absolute phase is the same. Both drivers went out together and pulled back together with the wires connected “wrong” according to Kencat. Tomorrow I’ll try it at higher volumes.

Another little test I did with playing music was to get down on my knees in front of one of the Quantums and position the midbass driver in front of one ear and a midrange dome in front of the other. There is sufficient overlap between the drivers that any difference in phase should’ve caused the weird effects heard when speakers are out of phase. Well, with the wires connected my way, the sound was the way it should be.

Maybe Infinity intended to use reflected sound to add a third dimension to the sound stage to work in conjunction with the rear EMITs for those Q2s with them. I just know that that arrangement does not work for me and the otherway does very well. Of course, come the Vancouver speaker shoot-out, I'll have an entirely different room to try the Q2s in and will do so both ways. Hopefully the others there will be able to bring their impressions to bear.

- JP

[Kencat]

As to East coast sound, I too am a fan of it, but the East coast sound isn’t excessive bass. You must be thinking of West Coast sound that is essentially defined by bloated midbass (~50-80Hz), no deep bass (sub-40Hz), and overly bright treble (typically 10dB above flat) all with high efficiency. Think Pioneer HPM-100, JBL, or Altec. East coast sound is more about tighter, flatter, and deeper bass that isn’t bloated, rolled off highs, and focus on the midrange.- JP

Nope. Have HPM-60s. OK in some scenarios, but not always.

Bloated midbass nor overly bright treble do it for me. Have a pair of AR2's. Nice easy listening East coast sound on an old HK 330C :thmbsp: :music:

The Q2s are way beyond these, nicely defined treble, but not "bright", large open midrange, and bass that is visceral. Different class of speaker.