ESS AMT-3 replacement woofer candidates

[kwingylee]

Today I was able to sufficiently modify my AMT-3 cabinets to accommodate the pair of Dayton RS270P-8A 10 inch woofers. I mounted and wired them to the stock crossovers. I also added a Lpad on the Alpha 6A midrange. I did not have the great Heils tonight but used my JBL 2404H and Electrovoice ST350A for the highs (would not recommend either one for this application without EQ). I am including a picture with the ST350A here.There is a 10 ohm resistor in series with the tweeter to pad in down... its barely tolerable.

To get a sense of the subjective quality of the AMT 3 bass with the new woofers. I drove them with a New American Sound/Bedini 100/100 Mark 2 amplifier (background to the right). It definitely performed much better than the Goldwood GW10PC-8 and Radioshack 10 inchers that I had in these cabinets before. Bass quality is very good and clean. The Alpha 6A need to be padded 1/2 way down on the Dayton 8 ohm LPAD to get the right tonal balance. Very promising sound so far. Next, I will add more bracing to the back of the AMT3 cabinets, sealed around the woofers and MAYBE line the walls with insulation. Of course connect the Heil tweeters.

The only drawback so far is that volume and efficiency wise, the AMT-3 cannot compare to the UREI 813As and the Altec A7s as seen in the backgorund. This is to be expected as the Altec/UREIs are around 100dB 1W efficient, and the AMT 3s are no where near the final product. I still need to seal the woofers and the port.

Has anyone ever measured the max SPL of the AMT-3s just to make sure my expectations are realistic?

 

[automojo]

Nice! They aren’t going to play as loud as a horn- but they play very loud, the lack of distortion/ compression throws you off to how loud they really are playing.
Next time I get a chance I’ll measure them
Most horns, for example start beaming near the drivers limits, because the sound waves wrap around in a figure eight, so the beaming/piercing effect adds to the distortion.
Newer horns have bumps to break up the soundwaves and keep them along the walls of the horn.
It's hard to get Great Heil, or Heils in general to really distort. Usually the fuse/circuit breaker blows/ or they melt. You won't hear your typical distortion.
I have a set of AMT3' crossovers, that clearly were clearly over driven, burnt one resistor, along with the board, and lifted part of that trace.
I'm sure the Heil diaphragm failed as well.
That's actually the same board I was working on tonight-reloading with Audyn's.
As mentioned-I had good luck lining all the walls-it will clean up the bass further-but minimum line the back, and one side wall to kill internal reflections, especially any that will reflect back through the woofer cone.

 

[kwingylee]

Well I have already blew the fuse....and can try to drive them with tube amplification with either my dynaco Mark 3 or the Conrad johnson mv55. These guys need at least 50w to 60w....

So far I like the way the alpha 6a blends with the woofers. Sound is seamless. Unfortunately looks wise they don’t match at all.

 

[jcidave]

At the small 2 man audio store I worked at in the 70's, we were an Altec dealer along with ESS. We had the A7 in inventory and also had the 846B Valencia on display along with the ESS AMT3's. The store's speaker switchboard allowed us to perform an instantaneous switch between the 846B's and the AMT3's. We would have one person adjust the volume control of what ever amp we were using to equalize the efficiency while we switched between speaker pairs. In doing this, I preferred the sound of the ESS 3's over the Altecs. The store owner agreed with me. So I bought the 3's with salesmans discount.
Kwingy, you certainly have a lot of equipment in that picture. Goodness Gracious!!

 

[automojo]

Well I have already blew the fuse....and can try to drive them with tube amplification with either my dynaco Mark 3 or the Conrad johnson mv55. These guys need at least 50w to 60w....

So far I like the way the alpha 6a blends with the woofers. Sound is seamless. Unfortunately looks wise they don’t match at all.

Sure...the more clean power in reserve, the better.
Sure, unless you find s mid with a cone...instead of a dust cap.
I keep my grills on..my don’t look the best either..but I like it.. with there history and all the different combos over the years...

 

[automojo]

Yep
When you’re playing the speakers

At the small 2 man audio store I worked at in the 70's, we were an Altec dealer along with ESS. We had the A7 in inventory and also had the 846B Valencia on display along with the ESS AMT3's. The store's speaker switchboard allowed us to perform an instantaneous switch between the 846B's and the AMT3's. We would have one person adjust the volume control of what ever amp we were using to equalize the efficiency while we switched between speaker pairs. In doing this, I preferred the sound of the ESS 3's over the Altecs. The store owner agreed with me. So I bought the 3's with salesmans discount.
Kwingy, you certainly have a lot of equipment in that picture. Goodness Gracious!!

When you’re playing the speakers loud, you don’t realize sometimes how loud they are because it’s so clean.
With a dB meter- you would be surprised!!
The drawback is you can easily drive your system into clipping.. blowing a fuse is no big deal, but melting a diaphragm sucks!

 

[automojo]

Today I was able to sufficiently modify my AMT-3 cabinets to accommodate the pair of Dayton RS270P-8A 10 inch woofers. I mounted and wired them to the stock crossovers. I also added a Lpad on the Alpha 6A midrange. I did not have the great Heils tonight but used my JBL 2404H and Electrovoice ST350A for the highs (would not recommend either one for this application without EQ). I am including a picture with the ST350A here.There is a 10 ohm resistor in series with the tweeter to pad in down... its barely tolerable.

To get a sense of the subjective quality of the AMT 3 bass with the new woofers. I drove them with a New American Sound/Bedini 100/100 Mark 2 amplifier (background to the right). It definitely performed much better than the Goldwood GW10PC-8 and Radioshack 10 inchers that I had in these cabinets before. Bass quality is very good and clean. The Alpha 6A need to be padded 1/2 way down on the Dayton 8 ohm LPAD to get the right tonal balance. Very promising sound so far. Next, I will add more bracing to the back of the AMT3 cabinets, sealed around the woofers and MAYBE line the walls with insulation. Of course connect the Heil tweeters.

The only drawback so far is that volume and efficiency wise, the AMT-3 cannot compare to the UREI 813As and the Altec A7s as seen in the backgorund. This is to be expected as the Altec/UREIs are around 100dB 1W efficient, and the AMT 3s are no where near the final product. I still need to seal the woofers and the port.

Has anyone ever measured the max SPL of the AMT-3s just to make sure my expectations are realistic?

View attachment 1642152

What the heck?
You pushed in the dust cap already?!

 

[automojo]

Man, I could never trust anyone to pack them securely enough to avoid damage anyway. It's one of those things you have to make a road trip out of - have a juicy-jugged red-head riding shotgun under the guise of a romantic road trip, but be up front about the gems at the other end of the journey.
Of course, be prepared to perform your manly duties once or twice along the way.

 

[StimpyWan]

Oh wow, you went back to the Mundorf's...! I knew you would.

 

[automojo]

Oh wow, you went back to the Mundorf's...! I knew you would. View attachment 1642979

Ahhh....no....they are x’d out..
I like dynamic music...not muted/ colored highs...
IMHO... It’s a testament to how great a driver the Great Heil is..
Frankly-in this application the Mundorf sounds more like Gee's take on the Audyn, and visa versa.
So much for "SPOT ON"!!
I have to say-Gee, I don't think ever gave a expensive cap a bad review. Doesn't that seem odd to you?
Anyhow-I certainly would take it for more then a general guide-and like anything else-buyer beware!!

 

[kwingylee]

At the small 2 man audio store I worked at in the 70's, we were an Altec dealer along with ESS. We had the A7 in inventory and also had the 846B Valencia on display along with the ESS AMT3's. The store's speaker switchboard allowed us to perform an instantaneous switch between the 846B's and the AMT3's. We would have one person adjust the volume control of what ever amp we were using to equalize the efficiency while we switched between speaker pairs. In doing this, I preferred the sound of the ESS 3's over the Altecs. The store owner agreed with me. So I bought the 3's with salesmans discount.
Kwingy, you certainly have a lot of equipment in that picture. Goodness Gracious!!

I was a drooling teenager back then,... going into audio stores and mostly lusting LOL. You are lucky to have actually worked in one and sounds like with really good stuff to boot.
Those are not normal A7s in the picture. They have the Hiraga A5 crossover and the Port has been shrunk to 75 square inches to make them behave like a mass Loaded transmission line, to go with the 511B/802-8D horn/driver and 416-8A woofers. They sound great. The fully recapped UREI 813As with the ALTEC 604-8G + Eminence 15" help woofer in front of them is my current favorite. I used Jantzen Superior Zs in the signal path and AEON film caps everywhere else when I recapped the very complicated crossover as they have built in delay lines to perform time alignment between the lows, mids and highs.
As with horns, the Altec stuff really needs tubes to sound their best. I suspect the AMT-3s will just suck up the Bedini's power.... we will see.
Yeah, there is a lot of stuff there. I should probably start selling some of it off... its just that,... I love them all.

 

[kwingylee]

Added the Heil tweeter today. The sound is just a tad bright but huge improvement over the unequalized Ev and jbl horns as well as a vifa dome tweeter I was using. They might even benefit from those Mundorf evo oil caps . I am in the process of adding bracing, sealing the cabinets and redoing the other amt 3. I really like the Dayton rs270p-8a woofers so far. Bass definition is excellent.

 

[kwingylee]

Added the Heil tweeter today. The sound is just a tad bright but huge improvement over the unequalized Ev and jbl horns as well as a vifa dome tweeter I was using. They might even benefit from those Mundorf evo oil caps . I am in the process of adding bracing, sealing the cabinets and redoing the other amt 3.

View attachment 1643159

What the heck?
You pushed in the dust cap already?!

I did not push it in. I bought them used on eBay that way years ago.... they were relative cheap. I really like the way they sound. Wish there was a way to fix it.

 

[automojo]

I did not push it in. I bought them used on eBay that way years ago.... they were relative cheap. I really like the way they sound. Wish there was a way to fix it.

Masking tape sometimes will work

 

[kwingylee]

Automojo:
I have been listening to the single speaker in a pseudo sealed box (the port does leak a bit). The bass sounds tight even without any stuffing inside. I will try it with some stuffing today... after I finish the other speaker.
I also need to redo the frame for the grill as its literally disintegrated. Will probably change the grill cloth in the process.
I plan to listen to the stock caps. Although I am about to order new caps to rebuild them. I don't plan to use Mundorfs because f the expense. I agree with you that the Heil does not sound like compression drivers and horns and likely not benefit from oil caps. I am buying AXON caps, the same company that makes Solens. There is a big sale on them right now.
I do hear differences between caps. Don't understand why. Just they do sound different. From my experience with active crossovers, even 0.2dB change in amplitude, if the change is broad, you will hear the difference. Its subtle and you need a very good voice recording to hear it. Especially in non-English songs (ex. Asian ballads). That phenomenon may be in play here..
There is something common in all oil caps in my experience. They do sound smoother and warmer..... the amount of details loss also tend to vary.

 

[kwingylee]

Completed the second amt 3 tonight. Partially stuff them with poly foam. They sound very good. Bass is tight and clean. The alpha 6a with the added L pad has a subtle effect. The woofers and the mid does not jump out at you but lays the foundation for the Heil to do its work. Image depth and width are both very good. I can’t think of anything major I want to change, except padding the Heil down a little.
As far as the way the RS270p-8 are performing, they are keepers for me and I would recommend them to anyone wanting to replace the amt3 woofers. The fact they are current models and still available make them viable candidates. In my experience although they weight less than the Goldwood GW10PC-8 woofers that I tried earlier, they sound much much better in the AMT3 cabinet. Note that I have never heard an all original amt3, nor the st255 nor the eminence 1040sf. It’s a ashame we can’t get together and have an amt3 shoot out.....

 

[kwingylee]

Next on the agenda is new grill substrate and possibly new grills to make them more contemporary. What should I be using to restore the cabinets ....?

 

[automojo]

Nice!
Nice to know there is now a currently available AMT3 woofer replacement!!

 

[kwingylee]

Nice!
Sure I agree caps do sound different. What I meant to say earlier is I don't think high dollar caps are a sure bet with the Heil.
that's good to know those are a viable replacement woofer. Thanks!
Yes-that would be awesome.
Axons look like a good cap-The Audyns seem fine-slightly bright-but that always goes away-The Daytons mellowed out as well, but it seems the Q4's are a bit more detailed-and less bright then the Daytons.

I totally agreed with your assessment. High dollar caps does not guarantee the most pleasing results. It depends on your system, your taste and you audio priorities. You can however, spend a fortune in caps to learn these lessons (You can get a decent active crossover for the price of some of these caps). I try not to throw my money around and try to read as much as about the caps as I can. I find in general there is good agreement among listeners about the sonic characteristics of certain caps, even with my limited experience and am fairly confident with using their views to guide my purchases.

Not sure if this is your experience, but I have found that cap swapping have a limited affect: smoothness, tightness of the image, glare reduction,... its one of the very last things you do to voice your system...

 

[automojo]

Sure.
Well my latest experience, is a good lesson not to work on your speaker crossovers inside the cabinet especially 10 o’clock at night!!
The Audyn’s... I have to say these weren’t broken in the original Dayton’s had hundreds of hours..
The Audyn’s in my opinion aren’t very good with the Heils...the have some air... but bright with congested detail.
I’m sure they need a break in period, but the Dayton’s, while they were slightly bright out of box were never like this.
Once broken in...the Dayton’s are neutral, but slightly ‘gray’ -flat in the response..
Nothing offensive... But the reason for this exploration, I thought it was possible to get better sound out of the Heil.
When I originally put the Mundorf Evo Oils in.. I did it inside the cabinet and I must’ve messed up both crossover somehow because they had low output on each speaker.
Took the crossovers out, installed the Audyns... eh.
After a phone conversation with the fellow AMT three owner that uses these particular Evo oils... I knew something was amiss
So I removed the crossovers and redid the leafs for the 33 ufs- and went with 16 gauge hook up wire.
Now there is no issue with a dB drop.
Go figure!!
Anyhow, they certainly appear as a worthwhile upgrade so far.
More detailed, and you can hear layers that were absent in the Dayton’s an Audyn’s (again only 30 hours on the Audy’s ).
It’s like, so far, installing a level up from your current preamp.
I use Bug Stars #1 record as a test record, because it’s really difficult for a system and speakers to really separate the different instruments and sounds.
Every system I have heard this record on, frankly it sounds different.
And then my opinion, not to be taken lightly but this is been the best rendition I’ve ever heard of this album..clearly the caps have a lot to offer the Great Heil... It’ll be interesting to see how they sound after 50 or 100 hours
Why they are relatively expensive I see there’s a seller on eBay that selling for per slightly over $100.
If you think about it, how expensive a new, different preamp as this might be a worthwhile option.
I will use the EVO Oils for the high/midsection on my second pair