Infinity QLS 1 Potentiometers

buddha6

New Member
Hi Folks:

New to the board and my first post. I was lucky enough to purchase a new set Of Infinity QLS 1's back in the last century - SN 700473/700474. They've been in climate controlled storage since I retired in 1993, along with the rest of the equipment.

We've now decided to settle back down in our home in Virginia and the equipment will be delivered during the first week of 2015. For the electrics, I use a Carver C1 preamp, two Carver M1.0t power amps - each configured mono to drive the Watkins, and a Carver M 4.0t for the upper sides. These will all be recapped as well.

I've gone thru most of the QLS 1 posts on the board and have decided to rebuild the XO's. The Watkin's woofers will be replaced with new ones. While I've learned a lot from the board posts, I have one question regarding the XO pots.

I know they'll need cleaning but I was wondering if anyone has physically replaced the pots with new ones? If so, were you able to find the 5 ohm, 25 watt pots and where? Being a bit lazy, replacement is a bit more appealing than reconditioning the old ones. :zoom:

TIA, for any advice anyone can offer.

Regards...
 
Welcome to AK. You were wise to store those speakers for future use. Good luck getting everything back together again.
Jim
 
QLS 1 Pot Taper

I should have asked this in my first post.

Given that I don't have the speakers physically in-hand yet, does anyone know the taper of the QLS1 pot?

TIA
 
it is a wire wound .. and I believe it's linear ( I stand corrected )


John M
 
it is a wire wound .. and I believe it's linear ( I stand corrected )

Thanks, but I'm unsure precisely what you mean. :) Do you mean linear or logarithmic.

My sense is that it is probably linear. I haven't yet stumbled on any 5 ohm, 25 watt, log pots in my on-line searches.

However, without knowing with some degree of certainty, which type, I don't want to order the darn things.

Ciao...
 
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Pots are in great shape!

Hi folks:

I was able to talk the storage folks to let me get my QLS's out of storage before all the other stuff is delivered next week.

When I pulled the crossovers I was greatly surprised to discover, at first blush, that the crossovers seem to be in like-new condition. No external rust/corrosion and none internally. Pics attached

Mine appear to be very different, though rated as in the schematic, than the ones I've seen in pictures on the forum.

I'll still clean them and treat with FaderLube but now have no need to look for replacements and can eliminate that cost from my parts list.

Thanks for the comments.
 

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Wow! They look brand new!

Leave the film caps and replace that red and black POS, it's bad for sure! Do you have an ESR meter to test the others with? It's the only way to be sure that they are still OK.
 
No ESR meter but I'm going to replace all the caps anyway. I'm going to replace the entire mounting board with a larger one (make it easier to work on and allow better spacing on the inductors) and replace almost everything except the pots.

One thing I'd like to do is segment the board into woofer, mid, and tweeter sections and lay it out accordingly. I haven't done so yet but I'll layout the schematic in PCB Express, based on the original Infinity schematic, and go from there.
 
Use film caps where Infinity did!

I recapped a pair of Qbs and I happened to have a poly cap the same value as the film cap that was on the tweeter. I figured I might as well switch it out "just to be sure". I noticed right away that the EMITs sounded dull. I switched them back and they sound good again.

Are your woofer voice coil #1 (red wire) caps 1,100uF or 1,600uf?
 
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Use film caps where Infinity did!

I recapped a pair of Qbs and I happened to have a poly cap the same value as the film cap that was on the tweeter. I figured I might as well switch it out "just to be sure". I noticed right away that the EMITs sounded dull. I switched them back and they sound good again.

Are your woofer voice coil #1 (red wire) caps 1,100uF or 1,600uf?

Both crossovers have 1400 and 1100 caps.

For my own edification, I redrew the schematics given that I'm replacing the mounting boards with ones measuring 10" x 13" which will give me more room to work and allow me to put some separation amongst the inductors.

FWIW, I've attached a PDF of the schematics. (If anyone looks at them and sees any errors, I'd appreciate you letting me know)

Best regards...
 

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QLS Restoration Tips

Congrats on getting these out and running again buddha6!

Great timing as I just got my pair back in commission for the first time since buying last year from original owner - serial numbers 7001464 and 5. All original drivers including the grey coated Watkins, everything works, but a bank of my mids went out immediately after I got them home and started fiddling with the pots. So, I too rebuilt my crossovers with great results. They sound marvelous again.

There is an amazing amount of info on AK for these speakers - Jim Reeves has been a huge contributor and source of useful info for me and many others to follow.

Here is what I learned beyond the readily known stuff:
>Though Infinity recommends bi amping horizontally (one amp for each speaker to tame the Watkins beasts) the bass can be overwhelming, so bi amping vertically with an amp that can handle the Watkins with gain control may be even better - I'm still sorting my amps, using a Sunfire 300~2 bi wired now but not enough juice when I crank it. buddha, mine drained my Carver TFM42 like a leaky coffee cup! My friend has 2 pairs of QLS and found Carvers were not up to the task, even bi amped. He is running Adcom mono blocks, also has a massive Krell and Parasounds.
>Infinity recommends use of the grilles as there is a diffuser bar between the mids and tweeters. If you run without, you can insert a diffuser for same effect (see Jim's posts)
>Correct position of the speakers is with the tweeters pointed toward the center (50/50 on tweeters inside or outside on photos all over the web); room placement is another topic
>Tweeters are wired in pairs - if one is out, will take the other one out too - check them by listening through a cardboard tube (like empty paper towel roll)

Here is what I learned and did regarding the crossovers:
>Easiest I think to remove the bases and just work on the caps, pots, etc all attached to the base (many posts on how to remove bases - remove woofer, then remove 8 screws, then tap with mallet, use putty knife and they are apart)
>Check your wiring - schematics all over here and really easy color coding to plug into the junction block:) My woofers were not properly connected!
>Recap the woofers! Those 2 large cans control the Watkins and I noticed a marked difference before and after. I used Parts Express NPEs and wired together to get the large values needed. Also replaced the other single NPE. I have read that NPEs in the woofers control damping so not recommend upgrading to film, etc. This saves money too:)
>I did not recap the remaining 5 yellow film caps - in hindsight, probably would do this while in there and you are done for good. Many opinions on whether film caps need to be replaced.......I'm not going there.
>Clean the pots - these things all have dead spots by now. The one that took out my bank of mids actually looked good but would not pass current down the center pole piece. Made of brass, had to drill out and replace with bolt and nut, works fine now. They are tempermental even when cleaned, may be best to replace them all if these are keepers
>Tweeter crossover setting seems best at Low position (subject to your room and taste) but gives most sound from EMITs down to 4K (mine sounded better in Hi or Low versus Mid and maybe because it's been on mid it's whole life and I didn't replace these caps?) Mine seemed to need some warm up time in the middle position then the veil lifted with some juice applied too. In Low they sound great immediately.

I am just now getting them dialed in, but this represents my collective notes from reading and restoring. Luckily, mine had been refoamed and done well, cabinets all very nice, as are grilles. All midrange tinsels in tact, and all EMITs working including the rear (which I have on).

By FAR these are the MOST inefficient speakers I've ever owned. I've had Carver Amazings, Martin Logans, and now have some large 86db McIntosh XR19s, but these take the cake! You need mega reserve, high current power or they will scoff at your gear. But, with the right power, the sound is absolutely rewarding - not veiled, but somewhat laid back; bass is absolutely stunning (my prior Polk SDA SRS 1.2 TL had the crown for deepest and lowest, but it's a tie now); imaging is amazing esp if you can position them right (I can't because I am a horder:); they get loud but easy to listen too.....takes you by surprise, kinda like when the Bimmer is doing 90mph and you think you're legal.

Hope this was helpful for anyone like Bucky too...saw Jim helping you along. I'll post some pics tonight.
 
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Thanks much for the tips...very informative and appreciated...particularly as I've never done anything like this before.

I've been wading thru the posts on AK and am amazed at the constellation of information available here.

All my equipment has been in storage since, at least, 1993 - when we decided to reside overseas - and is in excellent shape, but, I decided to rebuild the crossovers simply as a function of age and not extended use. Accordingly, my goal is to replace virtually everything in the crossover, including a larger mounting board. :)

I've started ordering parts, but am having difficulty finding the proper caps for the tweeter crossover plug. I found the 2.5uF, but can't seem to find the other two (1.25uF and 1.75uF) but I can get close with a series hookup.

Regarding a couple of your observations:

1. Using the Carver M1.0Ts configured in mono mode provides 1KW @ 8 ohms (I've never figured out what it is at 4 ohms) which, at my age, is more than ample. LOL

2. Before I pulled the backplate and mounting board, I looked at removing the bases but mine have small trim covering the mounting screws, so I simply pulled the whole shebang.

3. All of the pots seem to be in amazing condition compared to what I've seen posted here. In fact, they look new. The first thing I'll do is to measure them in "before condition"; clean/lube them with DeoxIT and Faderlube; and re-measure to see if there's a difference. They all "feel" good on the table but we'll see. I haven't yet found a replacement, if needed, but am told there's a couple of suppliers out there.

When I finish this project (assuming I survive that long), I have a set of Servo Statiks that have been "in-the-box" since 1972. At this point, I suppose they could be considered a "time capsule" similar to our VA house circa 1728. :)

Again, thanks for the tips.

Best regards....
 
Thanks much for the tips...very informative and appreciated...particularly as I've never done anything like this before.

I've been wading thru the posts on AK and am amazed at the constellation of information available here.

All my equipment has been in storage since, at least, 1993 - when we decided to reside overseas - and is in excellent shape, but, I decided to rebuild the crossovers simply as a function of age and not extended use. Accordingly, my goal is to replace virtually everything in the crossover, including a larger mounting board. :)

I've started ordering parts, but am having difficulty finding the proper caps for the tweeter crossover plug. I found the 2.5uF, but can't seem to find the other two (1.25uF and 1.75uF) but I can get close with a series hookup.

Regarding a couple of your observations:

1. Using the Carver M1.0Ts configured in mono mode provides 1KW @ 8 ohms (I've never figured out what it is at 4 ohms) which, at my age, is more than ample. LOL

2. Before I pulled the backplate and mounting board, I looked at removing the bases but mine have small trim covering the mounting screws, so I simply pulled the whole shebang.

3. All of the pots seem to be in amazing condition compared to what I've seen posted here. In fact, they look new. The first thing I'll do is to measure them in "before condition"; clean/lube them with DeoxIT and Faderlube; and re-measure to see if there's a difference. They all "feel" good on the table but we'll see. I haven't yet found a replacement, if needed, but am told there's a couple of suppliers out there.

When I finish this project (assuming I survive that long), I have a set of Servo Statiks that have been "in-the-box" since 1972. At this point, I suppose they could be considered a "time capsule" similar to our VA house circa 1728. :)

Again, thanks for the tips.

Best regards....

My pleasure, you are off and running for sure!

Definitely try the amps and as you noted, if you are not rocking at a major SPL, you should be fine. I have several Carvers myself, TFM 42, M4.0t and M1.5t, plus have owned many before and am a big fan.

Your pots do like like new, but they also look different than mine and all others I've ever seen posted….odd. Since you can get them in and out pretty easy and they look pristine, i'd recommend a cleaning only and try with the recap. Erse is a great source for caps in addition to Madisound and Parts Express.

Keep us posted!
 
Pics of my QLS

Here are a few pics of first arrival in the garage, cleaned up and oils, then some of restoration, then one in place in my main audio room (ideally, they should be alone in each corner….)
 

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