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

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On 1/3/2020 at 5:38 PM, ClaudeJ1 said:

I see no reason for stacking FH-1s, since they are at 104 db/w with a 4 ohm driver inside.

 

DJK used to use four LS bass cabinets per side, increasing the horn mouth size by 4... for better bass response.

 

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18 minutes ago, Marvel said:

 

DJK used to use four LS bass cabinets per side, increasing the horn mouth size by 4... for better bass response.

 

I thought he was using PPSL? That's all he talked about and showed in his DJ system photos.

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24 minutes ago, Marvel said:

 

DJK used to use four LS bass cabinets per side, increasing the horn mouth size by 4... for better bass response.

 

Define better? It's a SHORT HORN, so it may flatten out a bit at the low end, but it's still a 90 Hz. Horn with a sealed cabinet below that. You can't extend the bass by making a bigger mouth, you also have to LENGTHEN IT Also, which is precisely what is going on with the AMTs in this thread, lengthening them is doing way more than stacking.

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I know he used to stack the LS bass bins, although not for the volume. He told me he sometimes didn't hook up the extras, they were only for looks.

  • Haha 2

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14 hours ago, Chris A said:

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.

I think they absorbed the backwave as inticated in the picture. It looks like they worked on the vertical problem of dispersion and controlled the horizonal dispersion.

 

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). 

I didn't like the diffuse sound and vertical narrow dispersion. Side wall sound absorbtion may cure this problem.

Yes the AMT-1's are fully broken in. The Altec 828's are in corners of the room.

The AMT-1's are on top of the 828's on the inside front edge of the 828's..

There is a rack and equipment between the speakers. It sticks out about the same amount as the 828's.

 

Dimensions (length x width x height)?

10.5 foot X 13.5 foot. Speakers on the narrow walls.

 

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?

Yes, half the rear polar coverage is constrained or blocked by the 828 cabinet top. They are on the front edge and on the inside corners of the 828's. The 828's have towels covering the entire top of the speaker cabinet.

They are on the front edge of the cabinet so they are illuminating the floor.

 

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:

The 828's are front horn loaded and the back is ported. So the front horn is much louder than the back. To compensate for that the front horn should be padded down to match the back ported cabinet. If not there will be little bass because the horn overrides the bass. Once adjusted the mids are balanced with the bass. In my room the 828's go down to 35hz strong with a faint 30hz available, unequalized.

The 828's horn is the midrange so to speak. A lower frequency midrange but a midrange. I shelf down the horn starting at 240hz and above.

So to match the 2 AMT-1's to the 828's I padded down the AMT-1's.

 

828H.1.jpg

That's what I have. 828H

 

 

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).

I can hear the flatter phase response of a first order filter. It also has more ambiance.

 

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

I tried lower frequencies and there is a strident sound to the AMT-1's that I didn't like. Same problem with the 828”s if I cross them over anywhere above 1200 hz. There is just a distortion I don't like.

 

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

 

Chris

 

 

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You'll have to arrange a talk with him... it's what he told me.

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14 hours ago, Chris A said:

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.

No, I haven't put up any absorbtion material on the side walls. It would definitely help with sound bounce and smear. But by putting the AMT-1's on their sides they won't bounce the sound off of the side walls.The 828's I have are on wheels so the cabinets sit up 47 inches. If I had the AMT-1s setting normally and not on their sides they would be firing over my head because my ears sit 32 inch off the floor. And I angled the inside AMT-1's to fill in the center image.

 

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. 

You are right by angleing them in it does decrease the loading. But most people only use one per side anyway. Adding wings or a horn on the front will lower the frequency they will reach. But at what cost. Will they still sound strident? I don't know.

I could add absorbtion material on the walls but I would still have the vertical dispersion problem if I had them facing straight up as designed. If I could get them at ear level it would be a whole different ball game. People are going to have the same problem if they put them on top of Khorn's, Jubilee's or Jamboree's.

I will say my room is completely different then a lot of peoples. My room is small and that is what I have to work with.

 

Chris

 

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The 2 FH-1's per side that I use in my room in the corners will go down to 35hz. In a big room free standing probably 90hz or 60hz or whatever. But in my room 35hz. They say the same thing about Atec A7's that they will only go to like what 45 or 50hz. In my room 35hz. I had a radio engineer who also had his own band who sold me the FH-1's tell me I was crazy and was boosting or equalizing the bass to get the 35hz and that it would unload the woofer and ruin or blow it. He is right of course. But, But (I meant to put in 2 Buts) I am not equalizing them or boosting them.

 

I have run the FH-1's in series bi-amped with a horn mid-tweeter. I have also run them tri amped with a amp on each FH-1 and a horn mid-tweeter. Then run one FH-1 to like 100 or 200hz and the other to like 800hz. That way you can mess around with them and tailor them.

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13 hours ago, kennybugs said:

People are going to have the same problem if they put them on top of Khorn's, Jubilee's...

Actually, if you look at the height of the Khorn or Jubilee bass bins, they're 39 inches high.  This is almost perfect height for a double high stack of AMT-1s, which brings the center of each stack to 45 inches, almost exactly the right height (1.14 m):

 

ITU-R-BS-775-1.png

 

I recommend leaning your bass cabinets back or forward a bit to compensate, via placement of a piece of wood across the entire front or back of the 828 cabinet of sufficient height to geometrically intersect with your ear height at you listening position.

 

13 hours ago, kennybugs said:

If I had the AMT-1s setting normally and not on their sides they would be firing over my head because my ears sit 32 inch off the floor. And I angled the inside AMT-1's to fill in the center image.

The seated position is actually almost a foot lower than I sit in my main listening room and in my small computer room (the same size as your listening room).  My ears are at 42 inches or higher off the floor in these type of chairs:

 

shopping?q=tbn:ANd9GcT7l5zXYEdsYrJw1a1yz

 

If you sit that low, I'd recommend tilting the AMT-1s forward to aim their output more toward your seated ear height.

 

13 hours ago, kennybugs said:

...Adding wings or a horn on the front will lower the frequency they will reach. But at what cost. Will they still sound strident? I don't know.

I think that stridency you are talking about is harmonic and modulation distortion from the lower frequency operation of the AMT-1s without effective horn loading.  The cost is the price of some wood, etc. Placing them in double-high straight stacks and adding 8.5" long wing extensions to the AMT-1s will bring their horn loading down to ~400 Hz, which will alleviate the source of the problem (polar widening leading to higher motion of the diaphragm--much closer to the capability of the diaphragm's Xmax) at those frequencies, which is the cause of the harmonic and modulation distortion that you are hearing when crossing lower without the configuration mentioned, i.e., both stacked AND winged.  If you go to the fourth post of this thread, you will see a discussion and pictures about a third party horn loaded AMT that will play well down into the 300-400 Hz region (on the Rainier loudspeaker by Hawthorn Audio).  That was the genesis of the effort behind this thread.

 

13 hours ago, kennybugs said:

No, I haven't put up any absorption material on the side walls. It would definitely help with sound bounce and smear. But by putting the AMT-1's on their sides they won't bounce the sound off of the side walls.

This is actually incorrect.  The beginning of the audible side wall bounce will be delayed by 1.8 ms, which is exactly what the issue is by not having the absorption there in the first place: early reflections from the side walls. The rest of the room provides plenty of reflections to provide the sense of spaciousness and perhaps envelopment that I think you are confusing with detrimental early reflections.

 

13 hours ago, kennybugs said:

I will say my room is completely different then a lot of peoples. My room is small and that is what I have to work with.

Yes, but I have a small room of about the same dimensions as yours (with 8 foot ceiling--how high is your ceiling?) with a pair of Khorn clones (i.e., Shinall KKSs) in two corners that I intend to convert to this two-way configuration.  If I find any updated information about this exercise, I'll post it here.

 

14 hours ago, kennybugs said:

The 828's are front horn loaded and the back is ported. So the front horn is much louder than the back. To compensate for that the front horn should be padded down to match the back ported cabinet. If not there will be little bass because the horn overrides the bass. Once adjusted the mids are balanced with the bass. In my room the 828's go down to 35hz strong with a faint 30hz available, unequalized.

The 828's horn is the midrange so to speak. A lower frequency midrange but a midrange. I shelf down the horn starting at 240hz and above. So to match the 2 AMT-1's to the 828's I padded down the AMT-1's.

So you are actually talking about equalizing the output of both the AMT-1s and the 828 bass bin channels, right?

 

13 hours ago, kennybugs said:

The 2 FH-1's per side that I use in my room in the corners will go down to 35hz. In a big room free standing probably 90hz or 60hz or whatever. But in my room 35hz. They say the same thing about Altec A7's that they will only go to like what 45 or 50hz. In my room 35hz. I had a radio engineer who also had his own band who sold me the FH-1's tell me I was crazy and was boosting or equalizing the bass to get the 35hz and that it would unload the woofer and ruin or blow it. He is right of course. But, But (I meant to put in 2 Buts) I am not equalizing them or boosting them.

Yes, I believe you.  You're in the near field of your bass bin output starting at ~180 Hz in your room (based on your stated room dimensions, above).  This provides at least one octave of bass extension that you would other not get in a much larger room if the bass horns are not located in the room's corners.

 

14 hours ago, kennybugs said:

I didn't like the diffuse sound and vertical narrow dispersion. Side wall sound absorption may cure this problem.

Yes the AMT-1's are fully broken in. The Altec 828's are in corners of the room.

The AMT-1's are on top of the 828's on the inside front edge of the 828's..

There is a rack and equipment between the speakers. It sticks out about the same amount as the 828's.

Getting the midrange early reflections out of the middle of your soundstage will increase your perception of a phantom center image quite dramatically.  Anything that's acoustically reflective and anywhere near the height of your midrange--producing  horns/drivers will create strong interference in soundstage perception.  You might try moving the equipment and rack to one side of the other.  Try it.

 

Chris

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I will be following the progress on the double stack ESS AMT-1's with wings. Very Interesting and informative.

 

Kenny

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@Rudy81 how did you come up with 7 1/4” width for the wings? Have you tried any other widths?

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16 minutes ago, No.4 said:

@Rudy81 how did you come up with 7 1/4” width for the wings? Have you tried any other widths?

 

I started out with smaller prototypes which also worked.  After talking to @Chris A, he recommended wider for better response IIRC.  That width is simply due to the easily available stock.  Feel free to try wider ones and report back.

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3 hours ago, Rudy81 said:

 

I started out with smaller prototypes which also worked.  After talking to @Chris A, he recommended wider for better response IIRC.  That width is simply due to the easily available stock.  Feel free to try wider ones and report back.

@Rudy81 I have a huge stock of wood to use, so I may just do that. I will be using la Scala bass bins, so I will have to decide where I will set the heil on top (distance from diaphragm/ribbon to the front of the cab). That may dictate part of that length as well, unless extending them past the front of the cab has benefit. @Chris A any suggestions there? Directly over the woofers motor? Anyways, Rudy when you tested yours did you just hook the heils up to your amp and start your sweep at 400hz, or were you using the dsp? Did you test in room? I have REW and a mic, but I have not used it in awhile. It will be good to use it again, but I may need some guidance from Chris.

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40 minutes ago, No.4 said:

That may dictate part of that length as well, unless extending them past the front of the cab has benefit. @Chris A any suggestions there? Directly over the woofers motor?

Actually, the stacked/winged AMTs will have a tradeoff in terms of where to put them on top of the bass bins.  They need the top of the cabinet to close the third direction of the four-sided horn (with the wings forming the other two directions), so setting them back from the front of the cabinet should be traded against the loss of bottom horn loading and conversely against the loss of illumination of the floor in front of the loudspeaker.  This will need to be a "personal choice" type of adventure.  

 

The top of the AMTs actually benefit very little from being horn loaded, i.e., enclosing the top of the enclosing horn, and in fact, according to Rudy's comments, is better left open in order to retain that open airy AMT sound.  I've also noticed the same effect when I tried to enclose the top last year and found the big change in subjective sound quality that resulting from that enclosing. I was doing some polar measurements using REW and was interested in the effect of enclosing the top. 

 

The flip side of problem is the distance that the AMTs will be from the front wall--where their backwave is reflected and arrives at the listeners after the forward wave arrives.  So the farther away from the front wall you place the AMT assemblies, the longer the delay of the reflected rear wave to the listeners, and the greater the effect of soundstage depth, etc.  (I don't recommend placing the bass bins away from the front walls since you will be losing a great deal of bass extension doing so.)  The poster child for this conundrum is the Khorn bass bin, which is ~28" deep.  Without false corners, the Khorn bass bin cannot be pulled away from the room corner (for effective operation), so they will in 95% of cases likely be pushed into room corners.

 

So the bottom line is to try it both ways--at the front front of the bass bin cabinet and toward the middle or even the rear of the cabinet.  Listen for the effects of added spaciousness the farther away it is from the front wall, but the added distortion at higher volumes due to the lack of extension of the bottom of the horn. 

 

One way to have it both ways is to create a bottom plate to connect your wings to, thus enclosing the third side of the horn, sort of like putting backs on a Khorn bass bin in order to avoid using false corners, etc. Then you can move the stacked/winged AMT around to your heart's delight and listen to the subjective effects using different kinds of music and differing loudness levels.

 

AMTinstalled.jpg

 

Chris

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4 hours ago, Rudy81 said:

 

I started out with smaller prototypes which also worked.  After talking to @Chris A, he recommended wider for better response IIRC.  That width is simply due to the easily available stock.  Feel free to try wider ones and report back.

I want to try corner loading one with rear absorption to see what happens to the low end with a "Ultra Wide" wings, then try narrower and narrower, until there's not difference. Much like PWK said false corners were pretty much done enhancing the Khorn after 4 ft. I built those false corners according to the Dope From Hope over 4 decades ago. PWK practice what he preached because he had those in his house also. I like your "Feel Free" comment.

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3 hours ago, ClaudeJ1 said:

I want to try corner loading one with rear absorption to see what happens to the low end with a "Ultra Wide" wings, then try narrower and narrower, until there's not difference. Much like PWK said false corners were pretty much done enhancing the Khorn after 4 ft. I built those false corners according to the Dope From Hope over 4 decades ago. PWK practice what he preached because he had those in his house also. I like your "Feel Free" comment.

 

At this point I just want to forge ahead setting up what I have and taking the time to see how it sounds once completely set up. I experimented for some time and at this point just wish to get moving so I can later decide which system to use.  I'm sure as time goes on and we get more time and experience, many more experiments will present themselves. 

4 hours ago, Chris A said:

One way to have it both ways is to create a bottom plate to connect your wings to, thus enclosing the third side of the horn, sort of like putting backs on a Khorn bass bin in order to avoid using false corners, etc. Then you can move the stacked/winged AMT around to your heart's delight and listen to the subjective effects using different kinds of music and differing loudness levels.

 

AMTinstalled.jpg

 

Chris

 

That is why I created a bottom plate that holds threaded rods.  The rods and bottom plate will keep the drivers and wings in alignment no matter where you move the whole thing. Just happened that the drivers come with the holes for shorter rods.  My plan is to also attach a terminal strip to the back so as to keep the connections secure as I move the unit around.  I will want to experiment with the unit moved forward so there is no "bottom" to the front edge of the driver.  Also, move it back so the wings are flush with the front of my LF cabinet.  The Xilica will easily allow me to set up timing for both setups and allow for very quick settings swap during listening.  I have a feeling that type of evaluation is more suited to 'listening' than 'measuring'.

 

Should this project prove to be a success, then I can take my time and experiment with longer wings.  I would like to work on something like that once I have a good feel for the sound of the stacked drivers.

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Attention to detail seem to come into your build. Interested in your adventure. For Your Ears Only is

a theme could live in.

Thanks

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1 minute ago, billybob said:

Attention to detail seem to come into your build. Interested in your adventure. For Your Ears Only is

a theme could live in.

Thanks

 

I'm currently away at work, but by middle of this month I should have some initial impressions to share, at least on what I built.

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Just now, Rudy81 said:

 

I'm currently away at work, but by middle of this month I should have some initial impressions to share, at least on what I built.

I have patience. You must have quite a bit of the same. Somewhat exciting to understand, meanwhile

curious as to result.

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I spent all weekend reading through this and ancillary threads, dismantling my la scalas and brainstorming on how I'll use them for this project, lining up my final equipment list, etc. Still very much in over my head, but looking forward to this evolving over the coming months.

 

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