ESS AMT3 Heil Sickness-Continuing Saga Of Changes And Improvements

Still working on getting my second set together, however it's been a long winter of sick kids, sick wife, too many missed work days-whew! Long winter:sigh:
My nephew has taken a part time job at Electrovoice @ Burnsville. One of his projects will be reconing the early stock AMT3 Alnico 4 ohm woofers. A couple of differences between these and the later 8 ohm woofers are a deeper (and wider on the rear section) basket and larger voice coil, and slightly larger magnet structure. Heaier for sure than the later model Alnico's
http://www.audiokarma.org/forums/attachment.php?attachmentid=162955&d=1249345770
http://www.audiokarma.org/forums/attachment.php?attachmentid=215057&d=1276382127
http://www.audiokarma.org/forums/attachment.php?attachmentid=215055&d=1276381772
Since I will be using the later 3 coil 8ohm crossover, I also have these made into 8 ohm units-which is easier than going from 8 to 4 ohm-or so I was told.
While the drivers are torn down they will also check out the gauss of each magnet, and recharge if needed, and also even out the charge on all 4 drivers-taking into account the specifications of the woofers. So in the end each woofer will have a identical charge and DC resistence. Apparently these particuliar early ESS woofers have very high quality magnets/structure in them.
Interesting, as you see a fair amount of threads here trashing them-as I recall one "take a shot gun to them". Perhaps, in the case of the AMT3, the increased bass output of 2 vs one 10" woofer, along with the midwoofer of course, has alot to do with these speakers sounding so good. I also wonder about poorley assybled crossovers/parts that really didn't hold up over a period of time.
Personally, I never thought the stock woofers were that bad- as they have a warm and mellow sound, but they actually go fairly deep, and present a nice smooth and over all highly dynamic presentation- where as the 1040SF's are hyper detailed, forcefull, in your gut bass response and will truely rock the house. Each really has it's good points, and is clearly a matter of taste.

I also found that the 1040's need the port (if yours is ported)lengthened to around 5.25 inches.
For the mean time-I have decided to stick with the stock Alnico Peerless driver- since they are in great shape-and I'm really curious to see how these will preform with fine tuned stock drivers. RonC had good luck with his Audax and Dayton/Eminence woofers.
A couple pic's of the stock 4ohm woofers before reconing-and a almost wired 3 coil crossover. I managed to some how damage the stock 3 position brightness switch with a stray solder piece- but I found some nice heavy duty replacements from Digikey that were a bolt in, and under $10 ea.
This rebuilt crossover consists of Close spec Dayton Poly caps, 2 Janzen inducters, and one custom wound Meniscus inductor for the woofers-high quality 14 and 12 gauge wire-that will be colored keyed for the various circuits. Yellow for the Heil circuit, blue for the mid/transition driver, and green for the woofer circuit. When I get it done, I will take a more detailed picture. Hopefully it will be helpful to those who want to attempt a complete crossover over haul as well, and easier to follow how each driver is wired (and for myself as well!).
I will also add picture of the completed new 4-8ohm woofers as well. Some efficiency may be gained over stock, especially with 8 4 ohm 10 watt resistors in the stock 4ohm crossover woofer circuit. 2 inductors were used-with the 'resitors packs' (stacked and wired like multiple capacitors) feeding each inductor, which in the end added around 2-3 ohms of resistence to the woofer circuit. IMHO was a better, and much simplier design.
These 2nd pair of .AMT3's will also benefit from complely sealed mid tubes, strengthened and sealed main cab's, and reinforced baffle surfaces, like my first pair.
I also noted the the port tube on this earlier pair is shorter than my later pair- this one 2.75" x 2.5", while the later is 2.75 x 2.75". Same amount of stuffing in each.
In the end, hopefully this new thread will continue to be helpful to those that have AMT3's in vary states and condition wise/stock driver wise, or contemplating upgrades/improvements etc,or are just plain Heil addicts!!

Early AMT3-4ohm woofer Zobel Network

I have been recently trying and experimenting with the 2 main crossover designs with this speaker.
I am now deciding against reconing the 4ohm woofers- and will proceed to refurb the stock crossover.
Bob and RonC also have AMT3's that have this crossover design-the usual tip off is the CTS woofers and Peerless rubber surround midwoofer. All have Alnico magnets.
They also have 2 fuses-(1) 1.5 amp in the terminal board (midwoofers), and (1) 1 amp exclusively for the Heil. Mine will stay in place-never heard a difference in sound with a fuse-and it's better than melted diaphrams or voice coils. They are there for a reason.
In contrast to my earlier thoughts- this crossover uses a Zobel design to flatten the impedance of both the woofers and midwoofer (transition driver)-and in actuality seems to provide a slightly smoother and detailed bass response over the later design-of course at the expense of some power dissapation from the 8 resistors- and perhaps a very slight decrease in efficinecy-which is still very good- when you look at the post/review from 1975 (when this speaker was also produced)
http://www.audiokarma.org/forums/showthread.php?t=365572
A engineer @ Electrovoice also recommended sticking with the stock type electrolytics-as he feels-given the crossover design-their characteristics were taken into account-and substituting mylar or poly caps might result in inferior performance. Change is not always good.
He feels the design is superior to the newer design-in that it takes into account the specific woofer, and midwoofer driver and voice coil characteristics into the overalll design.
Yes they have a tendency to go out of spec over time (as these have)-but it's more like a routine maintenece thing.
El Seven- a true ESS expert (by the way we need to hear more from you my freind-as you are truly a treasure chest of ESS information:thmbsp:!)- also agrees the earlier design, components, cabinets were superior to the later designs-my ealier cabinets definitly are more solid-with no internal seam gaps to speak of-with the exception of the midwoofer tube being unsealed as well-but a tighter fit to the back wall.
I have always wondered about this-at least in speaker networks. Lot's of claims-but I always looked at them fairly skeptical-this cap is crap- this one is great-lot's of missing information in those claims IMHO.
I have to say- my first pair was recaped with stock electrolytics- and sounds fabulious.
I will post some pictures on this new project as well- as I have never seen much info on this crossover-and thought it was a bad design at first-because I really lacked the information and understanding to realize what was really going on-but I'm glad I found out, and also happy, as always, I save everything like this- and didn't throw anything away.
I disected one already- but nothing is ruined or lost, and should be actually easy to reassemble- I will recap, and replace the 8 resistor pack, as it took some force to pull it apart to see the resitor ratings.
Not sure of the 4 inductors values (the larger ones do look like the 2.4mh on the newer crossovers), but the cap values are (1) 20uf, (1)58.5uf, and (1) 14.5uf, for a total of three capacitiors.
Resitors values for (3) 2 ohm resistors, (1) 10 ohm resistor, and then the (8) 4 ohm resitors in the woofer/mid circuit.
I will try to get a decent picture of the PC board traces, and then the top w/ wiring- so it will make it easier to see how it works, and perhaps copy it as needed.
The fun begins yet again!!:thmbsp:.......
My AMT3's are a time consuming- but a very enjoyable project-and the results so far have been fantastic!.
Too bad ESS has decided not to remarket this speaker (with quality componets/construction @ El Seven)-because it honestly outperforms most speakers.
I was aware of Zobel networks before- and knew of their design goals-but never investigated on how they really worked and setup.
Working with these speakers has really been a knowledgeable and eye/ear opening experience-and I really appreciate all the help I've got from fellow members.

Allright, let me join in on this recent and most interesting thread I just came across.

Stashed in my music closet (for lack of a better word, it's an entire room) is a pair of ESS Amt3 Rock monitors, of which I am the original owner. I am waiting for the right circumstances to rebuild them. I thought it could be next year, but if this thread is helping any, I could be ready now.

Here's the story of my Amt3's.

Music lover first, and then audiophile, I went out in 1975 to find myself the ultimate pair of speakers. After numerous visits to audio stores for critical listening tests, it became evident that ESS speakers did stand out of the crowd, so i went for a pair of Amt1 Tower (rest of the system was a Quad 33/303 and an Empire turntable).

After a few weeks, i came to the conclusion that the Amt1's did not quite pack the punch I was looking for, so I bit the bullet, opened the wallet and came back with a pair of Amt3's. To this day, I have not heard loudspeakers more pleasing to my ears. It came close in 1996, where a pair of very expensive Infinity's could have been replacing the Amt3's but the wallet was not thick enough then. I remember so clearly, back in 1975, when I would bring friends over to listen to "Tank" (ELP's first album), and watch their eyes widen in amazement at the end of the drum solo, large bass drum kicks, goosebumbs, police knocking on the door every other week or so. Those were the good times.

Of course, the reason for replacing the Amt3's was the foam around the woofer's cone, or more exactly the absence of it, since it had pretty much vanished.

I attempted a rebuild in 2001, but money being scarce, I thought I would replace the woofers with only one per speaker. In order to do that, I selected very arbitrarily some automotive woofers of the wrong impedance. Reading all I could about crossovers, I also decided to rebuild them with new caps, so along the way, I kind of butchered one of them, tried to recreate the schematics from it, and I bought some unp caps and the coils to do the job. I still have those parts somewhere, but at the time, my electronics skills were too limited to complete the project. A few months later, still short on money to buy 4, I purchased another pair of woofers, not the same brand, but they would do for the time being. One crossover short, I bought a 2 way cheap xover, so I could at least hear the Amt3's once again, but I knew i would not be satisfied with this partial and not particularly good rebuild attempt, so they went back into the closet.

There was a glimpse of hope, a few years later, when the ESS company came back to life, but only for a little while, not long enough for me to get back to the project. Money was still too scarce.

There's not a day that goes by that I don't think about the gorgeous sound I used to listen to. But things have changed a few years ago, money is no longer a problem and my electronics skills have improved quit a bit since I got into collecting and doing some refurbishing of vintage Moog's.

So first things first... a bit of study, check the parts I have, build new crossovers or rebuild the old ones. Hopefully I will be able to bring back them Amt3's to their former glory.

Thanks for this post.

Crossover Types And Woofers

AMT3lover said:

Allright, let me join in on this recent and most interesting thread I just came across.

Stashed in my music closet (for lack of a better word, it's an entire room) is a pair of ESS Amt3 Rock monitors, of which I am the original owner. I am waiting for the right circumstances to rebuild them. I thought it could be next year, but if this thread is helping any, I could be ready now.

Here's the story of my Amt3's.

Music lover first, and then audiophile, I went out in 1975 to find myself the ultimate pair of speakers. After numerous visits to audio stores for critical listening tests, it became evident that ESS speakers did stand out of the crowd, so i went for a pair of Amt1 Tower (rest of the system was a Quad 33/303 and an Empire turntable).

After a few weeks, i came to the conclusion that the Amt1's did not quite pack the punch I was looking for, so I bit the bullet, opened the wallet and came back with a pair of Amt3's. To this day, I have not heard loudspeakers more pleasing to my ears. It came close in 1996, where a pair of very expensive Infinity's could have been replacing the Amt3's but the wallet was not thick enough then. I remember so clearly, back in 1975, when I would bring friends over to listen to "Tank" (ELP's first album), and watch their eyes widen in amazement at the end of the drum solo, large bass drum kicks, goosebumbs, police knocking on the door every other week or so. Those were the good times.

Of course, the reason for replacing the Amt3's was the foam around the woofer's cone, or more exactly the absence of it, since it had pretty much vanished.

I attempted a rebuild in 2001, but money being scarce, I thought I would replace the woofers with only one per speaker. In order to do that, I selected very arbitrarily some automotive woofers of the wrong impedance. Reading all I could about crossovers, I also decided to rebuild them with new caps, so along the way, I kind of butchered one of them, tried to recreate the schematics from it, and I bought some unp caps and the coils to do the job. I still have those parts somewhere, but at the time, my electronics skills were too limited to complete the project. A few months later, still short on money to buy 4, I purchased another pair of woofers, not the same brand, but they would do for the time being. One crossover short, I bought a 2 way cheap xover, so I could at least hear the Amt3's once again, but I knew i would not be satisfied with this partial and not particularly good rebuild attempt, so they went back into the closet.

There was a glimpse of hope, a few years later, when the ESS company came back to life, but only for a little while, not long enough for me to get back to the project. Money was still too scarce.

There's not a day that goes by that I don't think about the gorgeous sound I used to listen to. But things have changed a few years ago, money is no longer a problem and my electronics skills have improved quit a bit since I got into collecting and doing some refurbishing of vintage Moog's.

So first things first... a bit of study, check the parts I have, build new crossovers or rebuild the old ones. Hopefully I will be able to bring back them Amt3's to their former glory.

Thanks for this post.

Click to expand...

Nice-I love the ESS stories!. Nice to see a orignal owner AMT3 fan. made the mistake of selling my 1987 ESS PSS1220's-to buy a set of Klipsch-always missed the Heil magic-and managed to come across 2 pairs of amt3's within a year of each other.
Hopefully you still have the stock woofers. I am assuming since you didn't mention the mid needing refoaming, you have the earlier version with the 4ohm woofers and Peerless mids (rubber surround), and 4 coil 4 ohm Zobel crossovers. They also use (8) 4ohm resitors in the woofer circuit. These CTS 4ohm woofers, as I have found out are very good-large voice coils and nice Alnico magnet that works very well with the Peerless and Great Heil.
I was planning on using some Erse 3% tight tolerence electrolytics- but decided to deviat form my first pair and go with some Erse PulseX caps, and Lynk MOX resistors-with the stock coils.
I used P.E. electrolytics in my first pair (8 ohm 3 coil xover) and they sound wonderful.
There is enough room on the stock crossover board to run short jumpers from the circuit board to 2 of the caps-the 20 uf will sit on the board. Thnis way if I decide I don't like the polys-I can easily go back to the electrolytics.
I ened up purchasing both (some of the PulseX are on back order till 5-13) since the electrolytics amounted to less then $15 or so.
The PulseX are a good value, and are a bit shorter then the Dayton polys (which are very large).
It will be a interesting experiment- as I don't put alot into the 'designer' cap sound-as in my experience-first off you are usually replacing a worn out, out of tolerence cap-yep there will be a difference as the tolerences are now back in spec. The 3% tolerence in the PulseX (each is supposed to be tested to meet 3%) was intriguing-and that's why I chose this route.
Some of the expensive caps I see are 15% on up-not ideal IMHO. To me alot of time is wasted on caps types-this that-this ones is good-other is garbage-if the values are correct for the design, and the tolerences are tight- all should be good.
Also the MOX resitors in the Heil circuit, and woofer Zobel should be interesting. Not putting much into this either-but they where actually about the same as the Daytons and in therory should be totally non-inductive.
With the Zobel, there should be a slight difference between the early and later pairs in terms of midbass/midrange response-and my guess a sharper cutoff from the woofer to the Peerless.
The biggest improvements in my experience, aside form getting the crossover back in spec (and checking all wire connections/solder joints etc) are realized with the AMT3's by properly sealing the cabinet, and drivers-the midtube as well-(making sure you have all the proper dampening material as well) and blocking of the sides of the Heils-to prevent midrange cancellation-improving the midbass and imaging. Just basic stuff-no designer caps-silver wire-pixy dust-etc. No need to re-egineer.
Anyway-should be alot of fun
I have alot of info on these speakers in earlier threads-take a look, and please feel free to PM if you need help or questions, as I would be more than happy to help get these speakers up and running to their full potential.
I agree-AMT3's, when properly working/refurbished/etc beat out most speakers I have heard-imaging-dynamics-detail-and sheer musicality. People are truely stunned by how good they sound-especially for a nearing 40 year old speaker. Amazing in itself. And nothing specail was done with these-except basic stuff-recap sealing, etc- just some basic attentions to detail really.
Awesome to have another AMT3 fan join AK-Welcome!:thmbsp:


They are easily inde

4 and 8 Ohm Crossover Pics, Etc

A shot of the 4ohm 4 coil unit.
http://www.audiokarma.org/forums/attachment.php?attachmentid=215137&d=1276407528
http://www.audiokarma.org/forums/attachment.php?attachmentid=213976&d=1275799375
Note there are basically 3 cap in this crossover, as some are piggybacked to reach correct values: 20uf, 58.5uf, and 14.5uf.
And the 8 ohm-3 Coil Unit (rebuilt).
http://www.audiokarma.org/forums/attachment.php?attachmentid=168102&d=1252244885
And the 8 ohm Schematics below.

Thanks for your input. A few things....

Yes, the midrange speaker has a rubber suspension. Original woofers are long gone, but the replacements (2 x 8 Ohms in parallel for 4 ohms) sounded, from memory, as good as the originals, truly spectacular in fact. But that remains to be seen. I did not drive them as hard in 2001 as I did in the seventies, and then again only for a few months. Anyway, that is not a big concern for now. I know they sound good enough for the time being, and then, it will not change the crossover design.

Here are some parts of the original crossover.
On the first pic, two 55uF caps, 2 x (100+47 in series), equivalent to 32uF, one .33 mH inductor. Under the pcb board is the part number : 400-1012a
On the second pic, the crossover I used temporarily, Lpad for brilliance, and .83 mH inductor from original crossover
Not shown, larger inductor, inductance unknown.

Minimal difference as far as the posted schematic in concerned. 32uf instead of 33, and 55uf instead of 51.5. I don't remember the extra 4 resistors you are talking about and I have three coils total. They are assembled differently than the pics posted show, different board, different cap arrangement. It is a different version than your two pairs.

I am not sure I want to go overboard choosing caps and resistors. Over the counter preferred but non-p caps are not easy to find, especially exact values.

Contrary to the first crossover rebuild I had planned, I will keep the original inductors (much harder to find). I never used the brilliance switch so I am tempted to leave it out all together. Inspired by the high end guitar amps I now use, I am gonna go for a point-to-point wired circuit and leave out the pcb.

Unknown to me up to yesterday, I happen to be living close to a very good speaker parts distributor : Solen.

Because I can get the good stuff over the counter now, I will buy the best caps suited for my AMT3's.

Among these (see pic), which ones should I get a look into. Also, should I get metal film oxide resistors instead of wirewounds?

Really interesting stuff, guys. Keith, I'll be really interested to hear your assesment of the different caps. I used polys in my recap and after replacing the woofers I'll have to say I'm extremely happy with the end result. Don't think I'll go back to the electrolytics. I thank my late father regularly for my childhood exposure to music as well as buying my AMT 3s

I'm not sure how big a difference cap type plays-RonC has 3 pairs of AMT3's as I recall-some recapped with electrolytics others not-I think the tolerence is more important- when you look at the tighter tolorence NP caps- they are usally of higher quality (ERSE)-really the cap has a job to do- and one of them is not adding sound, or changing things-unless the design of the crossover meant it to- IMHO of course.
Good news- is these will all sound nice if done correctly.

Looks to me the crossover has already been worked on before-you must have additional pieces not shown-perhaps with the Peerless mids- this was a early 3 coil design. Most 3 coils have 2 33uf caps; two 51.5 uf caps, 2 .83 mh coils and one 2.4 mh coils. Those numbers are acceptable with a 10% tolerence.
Pernally I would keep the resistors and switch over the L-pad. The MOX type of resitors offer less induction. With The Lynk-they are less then 50 cents more then the Dayton sandcast.
Those inductors are easy to find value wise=but the O.E's should be fine, unless the got majorily overdriven or shorted out or "DCed".

AMT3lover said:

Thanks for your input. A few things....

Yes, the midrange speaker has a rubber suspension. Original woofers are long gone, but the replacements (2 x 8 Ohms in parallel for 4 ohms) sounded, from memory, as good as the originals, truly spectacular in fact. But that remains to be seen. I did not drive them as hard in 2001 as I did in the seventies, and then again only for a few months. Anyway, that is not a big concern for now. I know they sound good enough for the time being, and then, it will not change the crossover design.

Here are some parts of the original crossover.
On the first pic, two 55uF caps, 2 x (100+47 in series), equivalent to 32uF, one .33 mH inductor. Under the pcb board is the part number : 400-1012a
On the second pic, the crossover I used temporarily, Lpad for brilliance, and .83 mH inductor from original crossover
Not shown, larger inductor, inductance unknown.

Minimal difference as far as the posted schematic in concerned. 32uf instead of 33, and 55uf instead of 51.5. I don't remember the extra 4 resistors you are talking about and I have three coils total. They are assembled differently than the pics posted show, different board, different cap arrangement. It is a different version than your two pairs.

I am not sure I want to go overboard choosing caps and resistors. Over the counter preferred but non-p caps are not easy to find, especially exact values.

Contrary to the first crossover rebuild I had planned, I will keep the original inductors (much harder to find). I never used the brilliance switch so I am tempted to leave it out all together. Inspired by the high end guitar amps I now use, I am gonna go for a point-to-point wired circuit and leave out the pcb.

Click to expand...

automojo said:

Looks to me the crossover has already been worked on before-you must have additional pieces not shown-perhaps with the Peerless mids- this was a "inbetween design". Most 3 coils have 2 33uf caps; two 51.5 uf caps, 2 .83 mh coils and one 2.4 mh coils

Click to expand...

Hummmmm the plot is getting thicker. Too bad I don't have the original woofers but I am pretty sure I replaced two 8 ohms in parallel with same arrangement. The difference between coils puzzles me.

At any rate, the towers are still tightly stored in the storage room, with one of the original xover still intact. I'll have to dig them out before deciding what the next move will be, but most likely a replica of what's inside.

I won't worry about the Peerless-as it's 8 ohm-a good driver and the rubber surround is a plus.
The 8 ohm woofers are wired in parallel-as are the 4 ohms (with a Zobel).
It's possible they played around a bit with the inductor values-but you should have at least 3- and close to the .83mh values for the 2 smaller units-and 2.4mh for the larger one-and the 4 caps with in 10% of the 51.5 and 33.3.
Personally I would stick with the stock resistor scheme-you could upgrade to Mills-or MOX-the Daytons sound pretty darn good in my first pair. I know some Heil speakers use a l-pad- but also have some resistors involved.
If you plan on hard wiring the 3 coil design-play close attention to how those resistors are wired-and the rest of the componets-looking at you still stock one should help.
When I was originally planning to do the same-hard wired 3-coil- I made a drawing of the componet layout on paper/with the inputs/fuse holder etc, and then scetched in my wires-I got it wrong in a few places-and had to go back to the picture of the stock unit to get it right.
Of course your experience may vary-but I found it easy to miss a couple of things.
When I redo my 4 coil unit- I'm using the PC board-as it's a non-brainer-and the PC board quality is actually very good.

More mods....

I'm now looking at some more mods, concentrating on the front baffle.
I am looking at 2 ways to strengthen it.
1st going the route ronC did with one set-a single 12" 2x4 between the 2 woofer openings running horizontal. I think I can make 2 clean holes on each side with wood plugs to hide the screws.
I have experimenting with scrap and stain, and can make them fairly unnoticable. Not perfect, but close. I think one would also need to expoxy the front and 2 side attacments as well to make them more solid (i.e front edge touching the baffle, and 2 ends touching the left and right sides).
2nd making a 'knock down' of sorts of the front baffle, and attach this to the inside, thus elminating the need for the screws on each side of the cabinet.
The front baffle is more lively then what I thought, I also getting the feeling the box tuning may be off slightly, so I have a couple of different tubes lengths I am experimenting with.
I also picked up some extra AMT3 crossovers, I am looking at modifying slightly from stock.
I'm hoping the front baffle bracing will make the same amount of improvements in the bass and midbass as the total sealing job did.

AMT3 Cabinet Care- Klipsch KG 5.5's-Quartet's

I recently picked up a brand new AMT Heil still in the box-from the original owner- along with 4 brand new diaphrams-around $60 as I recall. But along with it came his owners manual for his AMT Monitors- sales brochure, and price list, and sales slip.
Finally got a chance to read the manual, and ESS recommended Scott's Liquid Gold-pourable version-not spray for finish care.
I always used this with my Klipsch KG's and had good luck-and it works well with the AMT finish. The AMT finish-even though a dated dark brown walnut, is actually pretty durable, and the Scott's really set's it off.
My last set of AMT3's was finaced by a trade of purchased new in 1996 Klipsch KG 5.5's. Great speakers, with there own kind of addictive sound-but the AMT3's really pointed out their recessed mids. The bass was pretty darn good-they obviously used the resonate cabinet's to tune the bass response (lining the walls with foam killed the bass response and changed the tone of the speaker, for the worse)- but it worked out fairly well-believe it or not.
Well missing that Klipsch sound, I found a near mint set of Kipsch Quartet's locally and couldn't resist-now missing the Klipsch sound.
By far a better speaker and a step up from the 2-way KG 5.5's- and those Crites titanium diaphrams I purchased for the KG 5.5's right before I sold them will fit right in.
I also plain a recap (maybe a Crites new x-over kit), and perhaps the Crites midrange diaphrams as well.
The aren't AMT3's by any stretch, a much more focused and narrow soundstange, and a more 'boxy sound'-but they are very highly musical, just like the AMT3's and really rock as well-nice tight natural and detailed bass-even with the passive. I like that they used paper cones with these vs poly drivers.
The TI diaphrams are said to smooth things out and provide a more organized detail-well see.
They are keepers-no more trading- I'm sticking with my current stable of speakers for now. They really seem to have alot of potential-and a managable foot print to boot.
Need to finish my SUPER AMT3's (half done-sort of a state of flux), LWA Econowaves, and a recap on my DLK 1 1/2's.
The Econowaves and DLK 'swill be for my twin daughters when they get a little bigger.
I really like to add a small Heil to those DLK's-the bass is very nice, and they are pretty darn efficient for a sealed twin woofer system-those little 8" woofers can rock! The ring cone tweeter is ok-but these things deserve a Heil!!:thmbsp:
Luckily the Magnepan SMG's are done, as well as my first AMT3 pair.
Except for a set of JBLs' I have aquired all the speakers I really liked in the past/future-until ESS comes out with a modern set of AMT3's I'm set...scratch2:-maybe?!)
It's funny-I go out and listen to new speakers all the time-great stuff out there-but despite technology advances-the only speakers I really like now, ones that can truely compete with the AMT3's, and even those Quartet's (their potential) are at least in the $2000-$2500.00, and even then some of these aren't close to being full range and require a subwoofer. I'm talking the whole package-tonal accuracy, imaging and soundstage, and performance at the frequency extremes-i.e. full range.
I reallize in part it's a price point thing.
Never liked the 3 piece subwoofer -great for HT-but totally ruins the imaging for music-as they always can be found at some point. A compromise in design that doesn't go well with music IMHO-HT fine-but I'm a 2 channel guy-DVD's and movies sound just fine to this cat with a nice set of AMT3's.
I still want to hear a set of those Direct Acousitcs Silent SPeaker II's-to me they sound like a true bargin-a full range speaker @ $750? In 2011/12? Awesome!!

Cabinet Mods Progress!!

Finally got some time to get my first brace installed, and it really turned out very nice. When you wrap your knuckles on the baffle now-it's very very solid, now a dull thud (almost like thick steel or a rock!!) instead of a 'ring'. It actually seems more solid then the side walls sound wise. I may just omit the second brace by the mid tube, as this seems to be just fine.
I took a 1x2 (pine-poplar will work as well), cut to 12" length wise. I drilled a counter sunk hole center in the middle with a #10 counter sunk bit. Then using this as a guide, drilled 2 out board counter sunk holes 1 1/2" in form each side. Then used a 7/64" bit to drill a piolit hole for the center screw, and tighten it and the brace, Using a tape measure inside on each of the brace ends, I measued to make sure the brace was straight across and level, and drilled 2 more pilot holes, and screwed them tight to make sure every thing was square.
While I used a #10 counter sunk bit, I used #8 2" screws. There is still plenty of wood left even with this larger bit, but it's easier on the old baffle board, and won't split the brace.
Marking off (2) 3 inch deep sections of the 1x2, I traced a 2 inch deep by 1 inch wide opening centered in each 3" section, and used a Dremel MultiMax tool to cut out the openings. The Dremel is a awesome tool, and the 1" wide blade is perfect for this application- A tool anyone doing woodwrok, wood repairs should have- it pays for it's self very quickly.
So bascially you end up with a "C" looking piece. I countersunk (again#10) 3 holes-2 on the legs of the "C", and one on the back, placed it on the board and drilled (6) "7/64" pilot holes, and ran the screws( #8 1 1/4") in. Then I removed the whole works, and liberally applied 60 minute epoxy to the mating surface of the center brace and screwed it down. Turning to the "C" braces, I also applied the epoxy to the sides contacting the side walls, and the inner "c" opening, pushed them in, and reinstalled the screws. The 1x2 is actually more like 3/4" thick, so with countersinking- 1 1/4" screws are fine, and won't be long enough to possibly penetrate the outside.
I then snugged all the screws up again and ran a final coat epoxy along all the edges/seams and all the entire 'C' brace surfaces (appears in a few pictures) to make everything nice and solid. Using acid brushes and some small yougart/apple sauce cups work well for mixing and applying the epoxy, although sometmes a few brissels come off- no big deal in this application-as I'm not fussy about what the inside looks like.
I will touch up the front baffle screws with a dab of black paint. I also will apply some thin foam of felt on each side of the brace to prevent the woofers back waves from reflecting directly back to the woofer cone.
Amazing how well this works, and it's really not that difficult. Be aware that the 60 minute epoxy really takes several days to fully cure.
The next step will be to silicone over the epoxy I put on the inner cabinet seams to insure a air tight seal. The apply the felt to the back, and perhaps sides (still debating this). I settled on f-13 1/8" felt for the back. WIth the large corssover board I'm using-this should work great.
I'm thinking of 1/4" felt for the sides, or perhaps Sonic Barrier, but have not made a decision on this yet. I may just run a few addtional 1" counter sunk #8 screws on each side and call it good.
Hopefully this will be helpful to AMT3 tweekers! And thanks to RonC for the ideas and info on the baffle brace!! Awesome!!:thmbsp:

1" Sonic Barrier!

I also took up RonC's advice on a picked up some sheets of this to line the interior walls on my first set- and will use it on my second set as well
It works very well, and adds some midbass/midrange calarity and seems to extend the bass response as well.
It was impossible to apply to the rears with the crossovers-so I left my sheet of convulted foam covering the back wall- directly in back of the woofers- the stuffing suports it so it doesn't need to be attached.
In my 2nd set, I will be using 1/8 felt to line the rear wall, and install the crossover boar over this-but I still may use a foam sheet-as even without the Sonic Barrier-it made a noticable improvement.
Not sure what RonC did on his rear wall-but from what I have read, and done research on-slowing the direct rear waves is more important then side wall reflections.
Here is a interesting take on stuffing vented enclosures.
http://sound.westhost.com/articles/boxstuff.htm

Just got the Sonic Barrier in-very good stuff!! Comparied to 1 1/2 inch convulted foam-it has a "sound sucking" that is far superior to the regular foam.
I just tryed this by putting my ear up to each piece-and the Sonic Barrier has a sort of sound vacuum ability that is remarkable. Dense, but soft foam with a interesting surface pattern.
However- I'm thinking of going with the 1 1/4" composite Sonic Barrier for the side walls and keep the 1" for covering the back wall. I talked with P.E. about sending some of it back-and he gave me another $5 discount to make up for the return shipping of the 8 1" panels.
It's expensive stuff-but ease of use, and wasted time trying to source other products-well it's probably worth it.
I also found some Quiet Kote spray I forgot I had for another project, and may use this on the rear walls instead of the felt. One can should be enough for 2 back walls. It has a oder-but dissapates fairly quickly. Too bad it's not water based.
The side walls of the AMT3 are very thick and solid-but I have been able to detect a weakness-a more hollow knocking sound-farther up the side panles around the midrange tube area. This may be in part because it extends up to the Heil compartment that is only 2 sided (and goes dwon to single layered 1 inch board) with a fairly weak brace that doubles as a support for the grill board.
I'm hoping using the 1 1/4" Sonic Barrier will help tune out this since adding a brace here would be very difficult.

Is the AMT3 ported? I thought I saw a reference to that somewhere. From the pics that I have seen elsewere i did not see any ports. Where there more than 1 version? The tube for whe maidrange was for isolation? Maybe that is what I found.
Thanks

The very last version was ported, to "improve" the bass response. I've read that this change was implemented after the original designers left the company. The low bass is slightly louder but some of the tightness of the upper bass is lost.

Chef's right-however I have a fairly early set-fairly low serial #'s-that has the 4 coil crossover/Peerless mid/and is ported.
The AMT3 cabinet is pretty stuffed-so the port is almost akin to a front mounted Aperiodic vent of sorts.
It will be interesing to hear what sort of improvement the Sonic Barrier will have with the Eminence 1040SF-as they have lot's more output compared to the stock Alnico's, and they could use a bit of taming down in the midbass.
I may also try sealing the port-as the 1040SF's can work with a sealed cabinet as well.