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Chris A

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

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One of the things that can be done with AMT-1 stacked in arrays greater than two-high is the possibility of forming a quasi-constant beamwidth transducer (CBT) that Don Keele has been pushing for a while now.  This is just like curving a line array that's hung from a stage ceiling in order to smooth out the polar directivity of the array to get a flatter directivity curve vs. frequency:

 

index.jpg.416c00607c7c6e9af04b54252c59262b.jpg

 

This could be done either physically like Keele shows in his CBT array, or done using DSP crossovers using a vertically stacked array and multi-amping to add SPL shading vertically and delays (i.e., see case "f" in the figure below).  With the low cost of AMT-1s, DSP crossovers, and good class D amplifiers, this is now an economically viable approach:

 

upload_2017-1-8_1-38-25-png.4422

 

Chris

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Hmmmm.....im almost thinking of getting a pair....much cheaper than bms two way....just cant get used to titanium drivers....too harsh. These EMT seem to be sounding smoother??

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21 minutes ago, Kalifornian said:

Hmmmm.....im almost thinking of getting a pair....much cheaper than bms two way....just cant get used to titanium drivers....too harsh. These EMT seem to be sounding smoother??

 

Yes. Just as articulate and revealing as the Klipsch heritage sound, but smoother.

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On 2/13/2020 at 12:19 PM, Chris A said:

Really, the issue is whether or not you're trying to use that dipole backwave like Rudy is, trying to get 99% out of it.  For my use, I place them on top of the Khorn clone bass bins, right in the middle of the top of the top hat:

 

AMT-1 on top of Khorn clone bass bin.jpg

 

I have no complaints.  If you're trying to get the same type of effect as a pair of Magnepans or MartinLogans, I can see where you'd want to move the AMT-1 assemblies away from the walls, but that's not possible if using Khorn bass bins (unless using large false corners).  This thread was started on the premise that many here would want to retrofit an AMT-1 assembly on top of their existing Heritage loudspeakers, and that's the way that I'm intending to use them.

 

I see no downside to this at all, in fact, it's a pretty big upside. 

 

Chris

A little surprised to see you using them this way Chris.  Active dsp no doubt.  How do you get it to mate well with the Khorn bass bin clone?  Can I PM you for your current  Xilica xdat file?

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I'm using a Yamaha SP2060 presently, so there is no Xilica file to share currently (and I don't have a working Ethernet connection to the Yamaha, so no visualizations there). 

 

I've do have a miniDSP 2x4 HD configuration file for my 1981 Belle bass bins and AMT-1s on top (bi-amped): 

 

Askew miniDSP2x4 HD settings 20 Jan 2020 - AMTs in middle of Belle top (6.79 inches back from front).xml

 

The channel assignments are:

input 1=left input from preamp

input 2=right input from preamp

 

output1=left Belle bass bin to amplifier

output2=right Belle bass bin to amplifier

output3=left AMT-1 to amplifier

output4=right AMT-1 to amplifier

 

(Note the scales in each plot.)

31435718_RightBelleBassBinAMT-1SPLPhase.thumb.jpg.8091ffcd16a122337f6bf20c7d9b8436.jpg

1069618364_RightBelleBassBinAMT-1GroupDelay.thumb.jpg.d2610f15ea90531c353c13b63800066a.jpg

1117098612_RightBelleBassBinAMT-1Spectrogram.thumb.jpg.e14414e9ff388ca9c5ea93c796596313.jpg

1544010891_RightBelleBassBinAMT-1HarmonicDistortion.thumb.jpg.b1d99ea980562abc3a60643e2ba5d6f0.jpg

435923215_RightBelleBassBinAMT-1StepResponse.thumb.jpg.ff379468fd1aa44d5359c035de372dd5.jpg

 

Chris

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1 hour ago, Delicious2 said:

How do you get it to mate well with the Khorn bass bin clone?

I'm still working on it. 

 

I had an infancy failure of one AMT-1 diaphragm when supplying a 2.7V pink noise input to it to break it in, so my stacked/winged AMT-1 with Khorn clone bass bins is still waiting on ESS to provide the fourth AMT-1 diaphragm that works.

 

I talked to Ricky Caudillo (the ESS CEO) on the phone, who graciously agreed to send me a replacement diaphragm as warranty replacement, but that was ~2 weeks ago and I still have no replacement diaphragm, and no response from ESS from my emails.  The AMT-1 driver is rated at 40 W input (no restrictions stated in their specifications), so there must have been a problem with the diaphragm in manufacturing to fail at 99 dB/1m after 5 minutes (nominally 2 W input assuming 3.7 ohm impedance).

 

Chris

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14 minutes ago, Chris A said:

I'm still working on it. 

 

I had an infancy failure of one AMT-1 diaphragm when supplying a 2.7V pink noise input to it to break it in, so my stacked/winged AMT-1 with Khorn clone bass bins is still waiting on ESS to provide the fourth AMT-1 diaphragm that works.

 

I talked to Ricky Caudillo (the ESS CEO) on the phone, who graciously agreed to send me a replacement diaphragm as warranty replacement, but that was ~2 weeks ago and I still have no replacement diaphragm, and no response from ESS from my emails.  The AMT-1 driver is rated at 40 W input (no restrictions stated in their specifications), so there must have been a problem with the diaphragm in manufacturing to fail at 99 dB/1m after 5 minutes (nominally 2 W input assuming 3.7 ohm impedance).

 

Chris

 

ESS is certainly backed up now with all our orders. I spoke to Rick a couple of times after I damaged my diaphragm as well.  I'm still waiting on a replacement and on a backup set of AMT's. I do know they are in the manufacturing process of a new batch of spare diaphragms.  Just have to be patient I guess.  My center channel is currently running with just one AMT since I'm such a dumb a**. Rick is a super nice guy and I'm sure working on all this as fast as he can. 

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I have enjoyed reading about how you guys are using these AMT drivers.  They must sound really good.

 

I wonder what the life expectancy for one of these AMT drivers will be?  Do they gradually "wear out" and/or degrade in sound?  Or should they normally outlast the buyer?

 

How well do they work in various environment conditions?  Does low humidity or high humidity affect them?  How about high/low temperatures?

 

Hopefully one day ESS will add some speaker wire binding posts to the back instead of having those wires that can be accidentally pulled out.

 

Mark

 

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2 hours ago, Chris A said:

I'm using a Yamaha SP2060 presently,

 

I'll be needing some hand holding at some point to adopt your method of nameless xovers on this specific model. I spent some time with the software (still waiting on the device to be delivered) and saw where I can passthrough the input signal without named xovers, but then it wasn't clear if I was supposed to use PEQ's or  HPF/LPF filters at the crossover points, etc.

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6 minutes ago, Thaddeus Smith said:

 

I'll be needing some hand holding at some point to adopt your method of nameless xovers on this specific model...it wasn't clear if I was supposed to use PEQ's or  HPF/LPF filters at the crossover points, etc.

When you start taking REW measurements, I can help via email.  You send your REW .mdat files, I can send back screenshots or text files of the PEQs.  For the crossover type that you reference (i.e., nameless, or I call them "fractional order" crossovers just like Tom Danley), there are no HPFs or LPFs used.  You use the natural response of the drivers themselves, and trim off the response that you don't need via PEQs.  That way, there are no phase shifts through the crossover bands.

 

Shoot me a PM if you want to try the email thing.  It usually takes about 3-4 round robin email cycles before you're within ±2 dB SPL response and dialed-in in terms of time alignment--which is usually the most time consuming task to coordinate with the SPL response around the crossover region(s).  You'll always have that configuration that you can switch to/from to try vis-à-vis other approaches using traditional HPFs/LPFs. 

 

Chris

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Can the "nameless" crossover be done through the mini dsp unit?  I must have missed it in the menu when using it if it's there.

 

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1 hour ago, Marks said:

I wonder what the life expectancy for one of these AMT drivers will be? 

Reportedly, the life of the diaphragms is decades (more than 35 years according to a German source that tested an old one recently), as I've seen more than one person state that they have ESS AMTs from the 1970s that still work.  The diaphragm backing material is made of clear polyester sheet with metal foil conductive channels deposited on them--much like a PC board, except flexible.  When you see a diaphragm up close, you'll understand. 

 

1 hour ago, Marks said:

How well do they work in various environment conditions?  Does low humidity or high humidity affect them?  How about high/low temperatures?

They don't seem to be affected by humidity or heat.  The soldered connections (2 per diaphragm) are the only failure points if they get too hot, apparently.

 

1 hour ago, Marks said:

Hopefully one day ESS will add some speaker wire binding posts to the back instead of having those wires that can be accidentally pulled out.

That can be done yourself if you prefer (e.g., an old AMT-1 that was tested by a German hi-fi magazine some time back):

 

 

ess_vorne-kl.jpg ess_hinten-kl.jpg

 

Chris

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29 minutes ago, Pete H said:

Can the "nameless" crossover be done through the mini dsp unit?

Any DSP crossover having enough PEQ filters (biquads) can do it.  See the following for the steps that you take:

 

https://community.klipsch.com/index.php?/topic/182419-subconscious-auditory-effects-of-quasi-linear-phase-loudspeakers/page/4/&tab=comments#comment-2388972

 

If you need assistance, send me a PM. 

 

Chris

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2 hours ago, Chris A said:

When you start taking REW measurements, I can help via email.  You send your REW .mdat files, I can send back screenshots or text files of the PEQs.  For the crossover type that you reference (i.e., nameless, or I call them "fractional order" crossovers just like Tom Danley), there are no HPFs or LPFs used.  You use the natural response of the drivers themselves, and trim off the response that you don't need via PEQs.  That way, there are no phase shifts through the crossover bands.

 

Shoot me a PM if you want to try the email thing.  It usually takes about 3-4 round robin email cycles before you're within ±2 dB SPL response and dialed-in in terms of time alignment--which is usually the most time consuming task to coordinate with the SPL response around the crossover region(s).  You'll always have that configuration that you can switch to/from to try vis-à-vis other approaches using traditional HPFs/LPFs. 

 

Chris

 

Will do, thanks Chris. I'll wait on this process until I have wings built and in place.

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2 hours ago, Chris A said:

Reportedly, the life of the diaphragms is decades (more than 35 years according to a German source that tested an old one recently), as I've seen more than one person state that they have ESS AMTs from the 1970s that still work.

I have pair that are from roughy 1972 that see daily duty. As far as I know they have the original diaphragms. I can’t say for sure though because I was manufactured in 1977.😀

 

outside of the diaphragms I don’t see how you could damage the magnet assembly.

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I finally got around to make a little saw dust. I have a lot more to do, but it’s a start. These are 12” wings. 

6B810050-0DF8-4F62-998B-E73215F492AE.jpeg

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10 hours ago, Delicious2 said:

Initial listen promising 😺

Keep us posted on what you hear, please. I am very interested in your impressions regarding soundstage and depth as compared to whatever you had previously.

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