ESS AMT 10b Woofer Recommendation.

[Bon Rener]

I have an old pair of ESS AMT 10b speakers that belonged to my dad. My dad used them all the time when I was a kid, but put them in the attic about a 20 years ago. He said they were good speakers but couldn't remember why he put them up there. I recently dug them out to try and fix them and use them myself. The current drivers in them are in really bad shape. The cabinet was full of hotwheel cars though so if I had to bet it was my little hands ruined the current drivers about two decades ago! XD

......... so I need some new drivers!

The current woofers in them are Pyle replacements from the 1980's (the originals are long gone). They're 10" woofers.

I'd like to get them back up and going. I'm building a silverface system they would be perfect for.

I'd like to know what my options are. I see that ESS sells replacements, but I've heard mixed things about them. I also found a guy selling some 10" drivers from an AMT 1 for a decent price. Would those drivers work?

 

[nomenclature]

I'd like to get them back up and going. I'm building a silverface system they would be perfect for.

I'd like to know what my options are. I see that ESS sells replacements, but I've heard mixed things about them. I also found a guy selling some 10" drivers from an AMT 1 for a decent price. Would those drivers work?

I would opt for originals. They show up on the bay routinely. The new woofers are thin paper and don't do power handling like they should do. The quality of the older woofers is good, a pulp cone that's lightweight. I had a pair of 10b in the nineties that kicked butt. Those tweeters sing nice.

 

[Porkloin]

There's a ton of woofers out there that would do the job better. Technology moves forward. What's the point of getting something of questionable history off of eBay when you can have new with a warranty for about the same price? If you're looking to "restore, hold out for OEM. If you're looking to listen, go over to Parts express and start pouring over the 10" woofer selection. You can filter your searches by size and impedence. PE also lists desired enclosure volumes in the specs on the woofers.

Original ESS 10" woofer -vs- Dayton ST255-8 - No comparison. Although the Dayton is now discontinued, it remains a demonstration of the great potential of modern manufacturing and should encourage pursuit of non-OEM alternatives.

 

[Bon Rener]

Thanks! It turns out the AMT 1 woofers I was looking at aren't actually the same as the ones that were in the 10b anyway, so I wouldn't be restoring anything by putting them in. I've been looking for some original replacements for a couple months now (ESS # 680-1052) and haven't found much. I was originally wanting to restore, but the more time goes on the more I just want to listen. I think I'll give your suggestion a try Porkloin. I do have one question though, what was the impedance of the original drivers? I don't have the originals so I can't test them myself. I know the overall speaker impedance is 6 ohm. I've looked all over the interwebs (including ESS's service manuals/schematics) and haven't found much.

 

[SleeperSupra]

Thanks! It turns out the AMT 1 woofers I was looking at aren't actually the same as the ones that were in the 10b anyway, so I wouldn't be restoring anything by putting them in. I've been looking for some original replacements for a couple months now (ESS # 680-1052) and haven't found much. I was originally wanting to restore, but the more time goes on the more I just want to listen. I think I'll give your suggestion a try Porkloin. I do have one question though, what was the impedance of the original drivers? I don't have the originals so I can't test them myself. I know the overall speaker impedance is 6 ohm. I've looked all over the interwebs (including ESS's service manuals/schematics) and haven't found much.

Why not call Ricky over at ESS and ask? Ricky has always been very helpful to me.

 

[jcidave]

I see today that the ESS seller who I've purchased from in the past has listed a pair of OEM 10 inch woofers on ebay. These were from the AMT 3 but I believe they would basically be the same for the AMT 1. These are the preferred ALNICO motors. Somewhat high price but shipping included. You might want to write to him and ask.

 

[sqlsavior]

There is a LOT more to matching woofers than size and impedance, not the least of which is sensitivity. Google "Theil-Small parameters" for the gory details. Parts Express fortunately lists the Theil-Small parameters of their woofers. You would want to match the parameters of the original drivers.

 

[jcidave]

Sorry, but I missed the OP's original request. There is another ebay seller selling what he claims is a pair of 10 inch cast basket woofs which have paper cones. The 10B had a cast basket woofer. I just don't remember when I was selling them, whether it was a paper or bexetrene cone. The other main line ESS product at that time that used 10 inch stamped frame paper cone woofers the were AMT-1, 1 Tower, 3 and 4. So, this pair for sale might work for you as an OEM replacement. As was suggested, you can call ESS, Ricky is helpful, but he was not there in the 70's and doesn't have that history of the product. You can also communicate with the other ebay seller, 83fj, and see if he has the correct woofers in inventory.

 

[ginetto61]

Sorry to jump here with a question a little OT. How low in Hz the Heil tweeter of the 10B can go ?
i see that in the model AMT 10B they are cut at 1400Hz ...
https://www.hifiengine.com/manual_library/ess/amt-10b.shtml

instead in the AMT 3 as low as 700 Hz ...
https://www.hifiengine.com/manual_library/ess/amt-3.shtml
in this case they even mention a superio Power Handling: 500W ... so it seems that the tweeter can provide very high SPLs below 1000 Hz without big issues. Is it true ?
i have a 2 ways in mind like a VOT but with the Heil tweeter in place of the horn
Thanks a lot, gino

 

[puppet]

ginetto61, the heil dispersion is about 90-100 degrees. It's common (should be), in better quality speaker systems, to match driver directivity around crossover frequencies. A 10" driver's dispersion is a good match to the heil around 1.5khz. The "in room" response of the speaker will tend to sound/measure seamlessly around the crossover of 1.5khz with those two driver combinations.

 

[ginetto61]

ginetto61, the heil dispersion is about 90-100 degrees. It's common (should be), in better quality speaker systems, to match driver directivity around crossover frequencies. A 10" driver's dispersion is a good match to the heil around 1.5khz. The "in room" response of the speaker will tend to sound/measure seamlessly around the crossover of 1.5khz with those two driver combinations.

Hi ! thanks a lot for the very kind and valuable advice. Let me elaborate ... a friend of mine owns a pair of 10B witht one woofer missing ... so i am manipulating him saying that he has no chance to find an original replacement (luckily he does not read this forum )
I would take the two tweeters that works and mate them with two decent 12" for a nice high quality monitor. Like one of those with a horn but using instead this wonderful Heil instead. So the cross point could be even lower than 1 kHz ... these is the dispersion of a 12" by Peerlees for instance

Moreover i much prefer this version of the tweeter closed on the back instead of the one dipole like I do not like dipoles at all ... there are already so many issues with conventional speakers in the room ...
and i do not understand passive reflex drivers ... i do not like them and i do not see them as very common

 

[jcidave]

Hello in Italy:
I believe the Heil used in the 10B is basically the same as the dual plate Heil used in later versions of the AMT4. The xover in the AMT4 is 1000hz. With the smaller diaphragm, I doubt the performance will be the same as the Great Heil used in the AMT3. So I would expect a higher xover frequency limit. ESS factory sells these replacement parts. You could ask them the what the low frequency design limit is.

 

[jcidave]

Hi ! thanks a lot for the very kind and valuable advice. Let me elaborate ... a friend of mine owns a pair of 10B witht one woofer missing ... so i am manipulating him saying that he has no chance to find an original replacement (luckily he does not read this forum )
I would take the two tweeters that works and mate them with two decent 12" for a nice high quality monitor. Like one of those with a horn but using instead this wonderful Heil instead. So the cross point could be even lower than 1 kHz ... these is the dispersion of a 12" by Peerlees for instance

Moreover i much prefer this version of the tweeter on the back instead of the one dipole like I do not like dipoles at all ... there are already so many issues with conventional speakers in the room ...
and i do not understand passive reflex drivers ... i do not like them and i do not see them as very common

ESS factory sells a cast basket 10inch replacement woofer that will physically drop in fit in the 10B cabinet. Now I don't know the impediance of the original 10 inch bextrene cone woofer of the 10B. I think the new woofer is 4 ohms and its impregnated paper cone. There is an Ebay seller who has many old ESS parts and might have one of the correct woofers. He is seller 83fj. I have purchased from him in the past. Your friend could contact him. Why reinvent this wheel? I would try to fix what you have.

 

[ginetto61]

Hello in Italy: I believe the Heil used in the 10B is basically the same as the dual plate Heil used in later versions of the AMT4. The xover in the AMT4 is 1000hz. With the smaller diaphragm, I doubt the performance will be the same as the Great Heil used in the AMT3. So I would expect a higher xover frequency limit. ESS factory sells these replacement parts. You could ask them the what the low frequency design limit is.

Hi ! thanks a lot for the very helpful reply. Clearly two quite different drivers i see. Then i understand the 1.4kHz crossover point in the 10B.
No more questions. Thanks again, gino

 

[ginetto61]

ESS factory sells a cast basket 10inch replacement woofer that will physically drop in fit in the 10B cabinet.
Now I don't know the impediance of the original 10 inch bextrene cone

woofer of the 10B. I think the new woofer is 4 ohms and its impregnated paper cone.

in case of using the original speakers i would really try to use two identical woofers I read that the cone material has a big impact on the tone of the sound
I would stick to two identical woofers for sure

There is an Ebay seller who has many old ESS parts and might have one of the correct woofers. He is seller 83fj. I have purchased from him in the past. Your friend could contact him. Why reinvent this wheel? I would try to fix what you have.

Thanks again for the very valuable advice. I will have to end first my negotiation with the friend. I understand that the 10B can be very good as monitors.
Asa i will get them i will take some pics of the drivers.
As i said i love the fact that this version of the Heil is closed on the back. I cannot digest dipoles.
Thanks a lot. Kind regards, gino

 

[puppet]

ginetto61, as jcidave suggests it's important to know the diaphragm limits. The longer the diaphragm, the lower the cutoff frequency, in general.

I'm with you on the dipole issue. Some rooms (highly reflective) can be a problem to integrate with dipoles. At lower spl they can sound nice but higher spl can turn the response into "hash". I use the big heil with the back wave cancelled, crossed over to a 15" driver @ 1khz. It's more of a constant directivity response which I prefer in this room here.

 

[bimasta]

This is subjective, but others share my opinion. The sound of the AMT "thins out" as it goes lower. It loses body and substance. It's tempting to run it as low as possible, to take full advantage of its remarkable clarity, but there are trade offs — one loses expressiveness. "Sound at the Speed of Light", as they advertised, can mean "sound" only, leaving musicality behind. I ran mine as 2-ways and my jaw dropped in awe at the transparency and detail, but inserting a very good midrange gave it so much more "feeling" and made long-term listening far more rewarding.

I wasn't correcting the "hole in the middle" created by the too-slow 12-inch old woofers, because there was none. It put "feeling" back into the Music — Violins sing more, the Blues hurt more, and Bob Marley is even more joyous.

Also, re the Woofer, and the "Original vs New" debate. I use newish, cheap no-name Polypropylene drivers I borrowed from an inexpensive pair of active home-studio monitors. I prefer it, and I've had several of the old ESS woofers to judge from. The light weight of the cone-material allows it to keep pace with the AMT's speed. It's high-efficiency makes it easy to integrate, and it'swell-made, with a vented pole-piece and butyl-rubber surrounds that won't decompose like foam. And a driver shouldn't have a "sound of its own" depending on what it's made of... though there may be a trace of it. A driver should be pistonic, and just move air.

 

[432HzBob]

Don;t need to get too fancy with things.
Unhappy with the Klipsch KG2 8" woofers and especially the tweeter, i came into some Heil tweeters and had some 1978 Infinity QB 10" woofers sitting for years.
I bought a Dayton Audio 2 way crossover that crosses at 2.5k, put a 3 Ohm resistor on the Heil and they blend real well with no hole I can hear.
I learned some time ago that a woofer isn;t just for bass.
The Old Infinity drivers have a decent lower midrange as well the way the center cone is, and deliver more than just whoomp whoomp bass.
Very happy with this project mod. The Heil's get to sing again and are mated to a woofer that rounds out their tone.

 

[puppet]

bimasta, on the flip side seems to me woofer choice is key if the heil is to be in a 2-way. The graph posted by ginetto61 would not qualify as suitable in a 2-way for me. That peak break up is too close to the xo region for my taste. You need a driver that preforms well a bit further beyond the intended xo. Such a driver adds body to the heil during transition. The cone is light and doesn't color the midrange. The directivity is a good match @1khz. The frequency response is pretty smooth through the xo region as well. System can output painful spl.

I don't miss the mid-driver.

 

[bimasta]

Yes! When I installed the woofer alone, at the start, I was astonished how far into the midrange it went, and how nuanced it was despite its mass. It was almost a Full-Range speaker. Also, the simple xover allows generous overlap, so the (surprisingly good) upper reaches of the Woofer supplemented and added body to the AMT's "thinner" sound at lower frequencies.

Again, my reaction is based on the cheap no-name Polypropylene drivers I borrowed from an inexpensive pair of active home-studio monitors. Nothing Hi-Tech, just basically well made. They handle most of the Cello's range on the Bach Solo Suites, and to my surprise conveyed both the Music's power, and its suite-ness (sorry).