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Chris A

Double Stack ESS AMT-1 with Wings--Possible Kit for Heritage

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49 minutes ago, kennybugs said:

My next thing to do is roll out the Altec's and roll in four Peavey FH-1's, two per side with Eminence drivers and see how that sounds with the Heils.

I see no reason for stacking FH-1s, since they are at 104 db/w with a 4 ohm driver inside. But stacking and winging the AMT's makes a lot of sense and difference in performance should be obvious. Turning them on their side for a 30" height, makes more sens for sit down sweet spot listening.

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So Rudy, how wide are the WINGS?

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7 minutes ago, ClaudeJ1 said:

So Rudy, how wide are the WINGS?

 

Each wing is 7 1/4" wide.  I wanted to keep the build as simple as possible.  I used Oak stock from local lumber big box.  Each piece started at 7 1/4" x 3/4" x 6'. I then cut the wing pieces at just over 12" to span the stacked drivers.  One edge was beveled at 45 degrees to sit flush with the driver.  The other end I routed half-round purely for aesthetics.  Super simple and inexpensive.  I'm sure somebody can improve on my idea, but that was my starting point.  I selected Oak since it was the stiffest hardwood they carry.  Turns out the Oak selection helped in the paint area.  Very minimal sanding was required with 320 grit to even the surface. Paint turned out really good on the Oak surface.

 

The wings are then glued and brad nailed to a base. In this case, some scrap Baltic Birch I had from a previous project.  I supported the wings with smaller oak pieces that also have a 45 degree bevel, which serve as a holder for the ends of the drivers.  I will run two rods through the driver pre-drilled holes to keep the drivers in place.  I also built a plywood top to finish the top and give it a standard 'horn' look. 

 

I plan on filling the voids you can see along the vertical edges of the driver/wing interface with black modeling clay, which I picked up from Hobby Lobby for $3. Frankly, I don't think I have ever built anything for my audio stuff that was this inexpensive.

 

I plan on placing the waveguide on four isolation pads to keep bass bin vibrations from affecting the AMT structure. Not sure if that matters, but what the heck.

AMTinstalled.jpg

Threaded rods.jpg

Paint1.jpg

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Thanks, Rudy. Now you go me thinking of making a 4 ft. tall version with 16 of these bad boys in a pair with an FH-1 horn or FH-1 modified to OB with twin 15" Alphas underneath. Wouldn't THAT be something!!

 

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16 minutes ago, ClaudeJ1 said:

Thanks, Rudy. Now you go me thinking of making a 4 ft. tall version with 16 of these bad boys in a pair with an FH-1 horn or FH-1 modified to OB with twin 15" Alphas underneath. Wouldn't THAT be something!!

 

 

Now you're cookin'

 

Edit: I am already looking around for an OB LF solution that can get close to 20Hz on the low end and cross two way with the AMT.  I have previously built H frame, M frame and W frame OB's but could not get them down in the 20's with my current Kappalite drivers.  I also tried building Ripoles, but they are very limited in the higher end of their response.  If I could find a good OB system to get me into the 20's I'd be all over them.

 

I am looking right now at the Eminence drivers used by the Pure Audio Project. 

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On second thought.  Disregard my OB comments.  I really want to try and keep this thread oriented toward the possible ESS kit for Heritage. 

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Ok, I've ordered the 4 drivers. The DSP will be soon-ish. And then I've got some cabinet work to do and figure out a time to build/paint the wings assembly, etc. I've got my 5 channel ATI amp idling with only 2 channels currently, so that's going to drive my HF and LF sections. Nothing changes for my SPUD clones setup. While I'm overhauling everything, should I also consider the Eminence Kappa-15C woofers? I believe I read that while they didn't go lower than OEM, they had better upper frequency performance when crossing over to the K400 mid horn and that seems relevant to what's trying to be achieved here. Or does that break the "Heritage HF upgrade kit" experiment goals?

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2 hours ago, Rudy81 said:

The other end I routed half-round purely for aesthetics. 

 

I'd wager that there are sonic benefits from doing that, and that they far outweigh the aesthetics.

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Posted (edited)
5 hours ago, ClaudeJ1 said:

I see no reason for stacking FH-1s, since they are at 104 db/w with a 4 ohm driver inside. But stacking and winging the AMT's makes a lot of sense and difference in performance should be obvious. Turning them on their side for a 30" height, makes more sens for sit down sweet spot listening.

 

There is a lot you can do with dual FH-1's per side. Saying you see no reason for stacking FH-1's is like a person saying (and I am not saying you said this) there is no reason for a Jubilee or Jamboree with dual woofers.

And I said 30 degrees angled in, not 30" height. And that is why I angled them in and put them on their sides is to widen the horizontal dispersion and to keep the outside ones from bouncing sound off of the side walls. I have the Altec's in corners for bass re-enforcement so the Heil's are also close to the side walls. And I sit in one spot all the time.

And stacking the Heil's straight up instead of sideways will help with vertical dispersion but won't cure it. Horizontal dispersion is not a problem.

Edited by kennybugs
correct spelling

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15 hours ago, kennybugs said:

...Look up the ESS AMT6 to see how ESS designed the AMT6...

cbr1n01syufwux5vllmk.jpg

1637912-ess-amt-6-professional.jpg

157008.jpg

 

The front wave is splayed outward, but the backwave will be aimed at a point on the rear wall, and the bottom wing of each AMT-1 is reflected off the top of the loudspeaker...thus screwing up the backwave pattern pretty much completely (assuming that a consistent backwave pattern is important).  And there will be coverage gaps between the drivers aimed at different splay angles.  The above photos indicate to me that ESS simply absorbed the backwave, thus killing the dipole effect in favor of the splay front wave (on its side).  Laying them down and splaying them looks like it creates a very complex polar coverage pattern.

 

15 hours ago, kennybugs said:

Finally I have settled with them on their sides, side by side with the outside ones straight forward and the inside ones about 30 degrees angled in. It gave the blend I wanted without the directional properties horizontally. Because on their sides they have good vertical dispersion but not good horizontal dispersion. My room is small and I just didn't like them straight up like they were designed.

Can you describe how you didn't like the sound? Were the AMT-1s fully broken in (i.e., at least 40 hours of normal listening volume) when you tried all of this?  How were the speakers located in-room relative to the walls/corners?  Were there any furniture/equipment racks/TVs in the middle between the loudspeakers at the level of the AMT-1s? (I.e., a picture of your setup would be nice to have). 

 

15 hours ago, kennybugs said:

My room is small

Dimensions (length x width x height)?

 

15 hours ago, kennybugs said:

Finally I have settled with them on their sides, side by side with the outside ones straight forward and the inside ones about 30 degrees angled in. It gave the blend I wanted without the directional properties horizontally.

I can see why you wanted to fill the horizontal dispersion of the AMT-1s in their sides.  However, half the polar coverage of the AMT-1s is constrained by laying them down sideways.  Have you moved them forward to the front of the cabinet such that they illuminate the floor, too?

 

15 hours ago, kennybugs said:

I still had to tweak the miniDSP to lower the Altec horn and Heils as both were too loud or hot.

It's difficult to interpret this sentence unless you're using some sort of midrange. Your system (A700-828) I thought looks like this, and is typically used as a two-way with some sort of segmented or cellular Altec HF horn on top:

 

828H.1.jpg

 

15 hours ago, kennybugs said:

Added delay to the Heils and it is sounding good. I crossed over the Altecs at 1150hz 6db and the Heils at 2000hz at 6db which gave a -4 db at 1514hz. I tried all kinds of crossover combinations from 500hz to 2000hz 48db, 24 db, 18db, 12db and have settled on the 6 db.

So you can hear the effects of flatter phase response using first order crossover filters?  This isn't a surprise to me as I found the same thing last year with all my 5.1 array loudspeakers (Jubilees, K-402-MEH center, AMT-1/Belle bass bin surrounds, TH subs).

 

Is there a reason why you didn't cross over at a lower frequency?

 

Thanks for sharing all this.  It's an interesting adventure just reading what you've tried and like/dislike.

 

Chris

 

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9 hours ago, kennybugs said:

And I said 30 degrees angled in, not 30" height. And that is why I angled them in and put them on their sides is to widen the horizontal dispersion and to keep the outside ones from bouncing sound off of the side walls. I have the Altec's in corners for bass re-enforcement so the Heil's are also close to the side walls. And I sit in one spot all the time.

This is already addressing the initial questions that I was first beginning to ask yesterday when I asked the question (but hadn't yet posted it--needing the continue through all of your comments).  Have you tried tacking up absorption material on the side walls next to the AMT-1s and woofers/horn?  This should significantly strengthen your phantom center image performance in-room.

 

Without wing extensions and by splaying the inside AMTs toward the center between the loudspeakers, the effect of acoustically loading the ribbons is decreased relative to stacking them vertically or horizontally in a straight line configuration, so you probably are still dealing with widening polars below 2 kHz. If you try stacking them vertically, add wings, and most importantly--add absorption the the side walls (at least 2 feet wide on each side and the height of the loudspeaker), you might like them a bit more in that orientation/configuration. 

 

Chris

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17 hours ago, Rudy81 said:

 

Now you're cookin'

 

Edit: I am already looking around for an OB LF solution that can get close to 20Hz on the low end and cross two way with the AMT.  I have previously built H frame, M frame and W frame OB's but could not get them down in the 20's with my current Kappalite drivers.  I also tried building Ripoles, but they are very limited in the higher end of their response.  If I could find a good OB system to get me into the 20's I'd be all over them.

 

I am looking right now at the Eminence drivers used by the Pure Audio Project. 

Have you looked at the 18" Goldwood drivers? They get to 30 Hz. in the right OB setup, but trying to get to 20 Hz. without more cones and severe EQ is tough. My friend build his award winning "Alphasaurus" OB bass with 8 Eminence Alphas per channel for a total of 16 and easily got down to 25 Hz. with ridiculously low distortion.

 

This is why I'm thinking of stacking a bigger pile of AMT's. I can test with 4 now, but could try 6, or 8 in the near future, just to see what happens. I really liked the sound of Carver Amazings and I had 3 pairs, now down to 2. Rather than "push" the ribbon, it's much better to "squeeze" the ribbon with accordion pleats, so to speak. Probably the closes thing to a compression driver using different methods.

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16 hours ago, Thaddeus Smith said:

Ok, I've ordered the 4 drivers. The DSP will be soon-ish. And then I've got some cabinet work to do and figure out a time to build/paint the wings assembly, etc. I've got my 5 channel ATI amp idling with only 2 channels currently, so that's going to drive my HF and LF sections. Nothing changes for my SPUD clones setup. While I'm overhauling everything, should I also consider the Eminence Kappa-15C woofers? I believe I read that while they didn't go lower than OEM, they had better upper frequency performance when crossing over to the K400 mid horn and that seems relevant to what's trying to be achieved here. Or does that break the "Heritage HF upgrade kit" experiment goals?

Since I think I'm the early/original/whatever discoverer/promoter of the great midrange attibutes of the Kappa 15C (best of 3 woofers in my Quarter Pie horn), lots of others have agreed. Since you have a solid subwoofer cooking down below, I'd say YES to your 15C ideas. Besides, they are still the best bang for the buck in 15's out there, which was the original reason for my promoting them here. Great sound, low price.

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forgive me if I missed the details in one of the previous posts but, I am assuming the two heils are wired in series to result in an 8 ohm measurement. With that said the drivers are rated at 96 dB 1W/1M. Does wiring these in series have any cumulative increase in the sensitivity of the driver? I ask because I am a tube amp user and probably won’t see much more than 5-9 watts. I read through a long thread on Diya about, this but every post seamed to contradict the previous. My diy la Scala should be around 104db, so I really don’t want to lose too much sensitivity.

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51 minutes ago, No.4 said:

My diy la Scala should be around 104db, so I really don’t want to lose too much sensitivity.

A DSP crossover and bi-amping solves this issue.  BTW: this thread is not really discussing passive crossover use with stacked/winged AMT-1s (see the original post, above).  You can get a good DSP crossover (2 in, 4 out for two-way use) for $204--if money is the issue. 

 

The "sensitivity loss" issue with passives when swapping out drivers of varying sensitivities is but one of the Achilles heels of passive crossovers.  (There are more issues with passives.  I really don't recommend them for this type of project.)

 

Chris

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37 minutes ago, Chris A said:

A DSP crossover and bi-amping solves this issue.  BTW: this thread is not really discussing passive crossover use with stacked/winged AMT-1s (see the original post, above).  You can get a good DSP crossover (2 in, 4 out for two-way use) for $204--if money is the issue. 

 

The "sensitivity loss" issue with passives when swapping out drivers of varying sensitivities is but one of the Achilles heels of passive crossovers.  (There are more issues with passives.  I really don't recommend them for this type of project.)

 

Chris

I’m sorry wasn’t more specific. I would be ditching the passive crossover for this project. My worry is the loss of sound pressure and volume if I lost some of the efficiency of a 104 dB system. Or Am I missing something? Does the DSP account for this to “push” the AMTs closer to the bass bin, or is the bass bin attenuated to the AMTs?

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Sorry, I totally misread your intent. 

 

You will experience a net gain in the bass bin efficiency due to removing any reactance between the amplifier and the woofer(s) in the form of a passive network.  Thats a net gain in efficiency/sensitivity in the bass bin. 

 

The AMT-1s have (variously) been rated at 96 dB(1 m, 2.83v) and 100 dB (ditto).  When you put wings on the AMT-1, it gains about 2.7 dB (ave) below 2 kHz.  Then you stack two AMT-1s, you get a 2-3 dB gain in output overall.  So the winged/stacked AMT-1 assembly is either getting 96+2.7+2 (=100.7 dB sensitivity overall gain) or it is getting 100+2.7+2 dB (104.7 dB sensitivity).  Either way, you're getting very close to the flat out sensitivity of the bass bin, which is usually the least sensitive/efficient part of a loudspeaker. 

 

In this case, the La Scala-based AMT-1 (full range) system is getting something like 100-105 dB "sensitivity" overall, but the least efficient part of the system is the midrange/tweeter section. 

 

The real problem is that sensitivity and/or efficiency loses its meaning once you start talking about bi-amping/tri-amping.  I can say that you will easily get 105 dBSPL out of your single modified AMT-1-/La Scala bass bin based setup in-room (each loudspeaker) without audible distortion--for a total of ~108 dB in room from two loudspeakers--without audible distortion.  They will play much, much louder, but distortion will start to become audible above those levels.  That's pretty loud. 

 

If you regularly play your loudspeakers above this level (and I am aware that there are some people on this forum that do--probably because they have lost a significant portion of the hearing acuity due to listening to sound at those levels over the years), I don't recommend using a dual-stack AMT-1 on top.  Perhaps those people need a quadruple-stack AMT-1 assembly to keep up at 110 dB in-room and above--or instead go with a JubScala type arrangement with 2" compression driver on a K-510 or K-402 horn.

 

Chris

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@Chris A

 

Thanks for the explanation Chris! Great info as usual. I have two amp projects in the cue but I may have to slide this project ahead of them. I have been dying to build something around the Heil, but I only bought one pair while they were initially on sale. I guess I’m off to order another pair!

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2 hours ago, Chris A said:

If you regularly play your loudspeakers above this level (and I am aware that there are some people on this forum that do--probably because they have lost a significant portion of the hearing acuity due to listening to sound at those levels over the years), I don't recommend using a dual-stack AMT-1 on top.  Perhaps those people need a quadruple-stack AMT-1 assembly to keep up at 110 dB in-room and above--or instead go with a JubScala type arrangement with 2" compression driver on a K-510 or K-402 horn.

 

Chris

I got a good laugh about this, even thought I think your were being serious. LOL. Too many garage band experiences here. LOL.

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