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Old 2nd January 2013, 03:08 PM   #1
john65b is offline john65b  United States
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Default My Acoustat Panel Experiment

Hey all, I have a few Acoustat panels and I/F's laying around and getting ready for my next experiment...

I have always liked the bass of my Model 3 - just solid and true. It didn't have the impressive slam of the Tympani IVa panels, but impressive nontheless.

I have never been a big bass dude until I got my T-IVas. I went through many Subs only to be left disappointed. That was until I got a ML Depth. Now this is a nice Sub, but not cheap or really what I wanted to mesh with my CLS. But I was impressed with the sound most likely due to the sealed, triangular isobaric design setup....that was the ticket to realistic, and somewhat deep, bass.

So here is my plan. Take three 9" 3 wire panels and put them in a sealed triangular setup, use the MK-121-2A I/F I have that has bias bumped to 6kv, and take out the HF tranny, and all post LF tranny components (no Caps/Resistors, etc), and use the 4 panel tap. Run the LF output from my DCX-2496 (around 150hz?) to an Icepower 1000ASP amp, and everything else to the HF amp setup of the modified CLS panel (another little experiment that I will discuss later).

Crazy?

The other option is to leave the three 9" 3 wire panels flat dipole arrangement like the Model 3, with bass I/F setup as described above
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Last edited by john65b; 2nd January 2013 at 03:13 PM.
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Old 2nd January 2013, 07:59 PM   #2
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Quote:
Originally Posted by john65b View Post
Hey all, I have a few Acoustat panels and I/F's laying around and getting ready for my next experiment...

I have always liked the bass of my Model 3 - just solid and true. It didn't have the impressive slam of the Tympani IVa panels, but impressive nontheless.

I have never been a big bass dude until I got my T-IVas. I went through many Subs only to be left disappointed. That was until I got a ML Depth. Now this is a nice Sub, but not cheap or really what I wanted to mesh with my CLS. But I was impressed with the sound most likely due to the sealed, triangular isobaric design setup....that was the ticket to realistic, and somewhat deep, bass.

So here is my plan. Take three 9" 3 wire panels and put them in a sealed triangular setup, use the MK-121-2A I/F I have that has bias bumped to 6kv, and take out the HF tranny, and all post LF tranny components (no Caps/Resistors, etc), and use the 4 panel tap. Run the LF output from my DCX-2496 (around 150hz?) to an Icepower 1000ASP amp, and everything else to the HF amp setup of the modified CLS panel (another little experiment that I will discuss later).

Crazy?

The other option is to leave the three 9" 3 wire panels flat dipole arrangement like the Model 3, with bass I/F setup as described above
I think that placing the three Acoustat panels in a "sealed triangular set-up" would destroy much of the magic inherent in a dipole speaker. I would recommend leaving them in their original slightly-curved array. Excursion might also be limited by placing them in a sealed enclosure.

Also, your desciption of how these panels would be used leaves me a little puzzled. What frequency range would they be used for? If you have a subwoofer, and CLS main speakers, where do the Acoustat panels fit into that scheme? Or is it your intent to use the Acoustat panels as the subwoofer?

Not sure what results you might have using only LF transformer in the Acoustat interfaces. In the original design, the HF and LF transformers overlap considerably in frequency range. Having never tried it, I can't say what odd behavior might result. Might be okay, might not.

Maybe you can shed a little more light on the configuration of the final system.
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Old 2nd January 2013, 08:40 PM   #3
john65b is offline john65b  United States
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Quote:
I think that placing the three Acoustat panels in a "sealed triangular set-up" would destroy much of the magic inherent in a dipole speaker
I thought so, but the LF is less directional at frequencies I would be running them - 150hz and lower.

Yes, the Acoustat triangle setup would be the subwoofer....so just the Acoustats as a triangular base, with CLS about 3' off the floor, just to the side of the Acoustats.
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Last edited by john65b; 2nd January 2013 at 08:42 PM.
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Old 3rd January 2013, 01:37 AM   #4
ehous is offline ehous  United States
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Acoustats, in my opinion (27 years) work off the back waves and room loading. using an RTA, you should be able to locate the best location for the flattest bass response from your listening position. True RTA basic is free download and using a basic calibration mic off eBay into a pc mic input will provide good enough results. I imagine loading them into an enclosure could work, however sizing it will be tough. Enclosures too small raise the fc. 1215 cubic inches of driver is equal to two 15" woofers. The small enclosure woofers work off high wattage and eq boost below the FC of the small enclosure.

The other issue I see is time alignment. Electrostats are line source and perform so well because of this. Adding a driver out of line with out a time delay will not sound coherent.

That being said, I look forward to reading the results proving me wrong. I have built some odd Acoustats in the past trying to reinvent the wheel.

Ed
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Old 3rd January 2013, 04:17 AM   #5
john65b is offline john65b  United States
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I can understand the doubts...

I read up on some who have sandwiched a pair of Tympani bass panels together in Isobaric arrangement and was also wondering what two Acoustats 9" panels would do...Good thing I have a few panels and I/F laying around...

I have the Behringer DEQ2496 and the EMM Mic to do some RTA on the setup and room.
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Old 3rd January 2013, 05:50 AM   #6
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The David Lucas ESL Subwoofer system used panels in a triple diaphragm isobaric arrangement.
It was used as a corner loaded method as per the plans.

I have not yet built such a system but have been pondering it for quite some time as I need to make about 6 panels for just one speaker.
Four of panels per side may be enough as well for a smaller system.
Or maybe 8 of them per side in a 8' tall double diaphragm isobaric setup.
Two panel assemblies are arranged in a 90 degree V and is each placed in the room corners with a small distance from the walls.

It is my belief that multiple diaphragms in a Isobaric configuration may help to have a better controlled diaphragm movement at the lower frequency's for very large excursions.
Thus lowering the THD's for sub frequency's.

Some where I have read that ML's CLS uses two diaphragms in there bass panel.

It will be very interesting to hear of your results of such a system.

jer

Last edited by geraldfryjr; 3rd January 2013 at 06:04 AM.
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Old 3rd January 2013, 06:49 AM   #7
Calvin is offline Calvin  Germany
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Hi,

A double diaphragm system increases the force per area unit and as such the SPL. This works quite well as long as the phase- shift between the diaphrams remains small enough. The effectiveness and bandwidth drops with increasing number of membranes due to the law of diminishing returns and distances.
The typical way of implementing is to stack n diaphragms and n+1 stators (see ML's CLX. The CLS and CLSii were single diaphragm designs)
I use a different system with n membranes and n curved stators.
Building such panels is like sweating blood and tears. But the heck...if You hold worlds best panels in Your hands then its worth the effort

Jauu
Calvin
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Old 3rd January 2013, 07:18 AM   #8
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Thank You Calvin, I knew it was one of them...I forgot.....The CLX !!! He,he,he,he

Yes, The extra labor !!!!!
The love of labor and having the best at the same time!!!



jer
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Old 3rd January 2013, 03:40 PM   #9
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Quote:
Originally Posted by john65b View Post
I read up on some who have sandwiched a pair of Tympani bass panels together in Isobaric arrangement and was also wondering what two Acoustats 9" panels would do...Good thing I have a few panels and I/F laying around...
As Calvin already mentioned, stacking two ESL panels closely one behind the other increases the force per unit area...nearly doubling it with close spacing. This resulted in a 5dB - 5.5dB sensitivity boost in my test cases. But, remember the increased SPL for a given input voltage is coming from increased diaphragm motion due to the larger force per unit area. So, with the Acoustat panels, you will find the maximum output in the low bass limited to the same output you had before stacking panels. The difference will be that you will reach the limit(diaphragm slapping stator wires) with about half the audio input voltage. For higher maximum output, you would need to rebuild the panels with larger D/S spacing.

There is one other effect you will notice when stacking two ESL panels that is not necessarily desirable if subwoofer is the intended use...the resonance frequency goes up by about 20%. So if single panels have Fs = 35Hz, when stacked closely together the combination will have a resonance of about 42Hz. The explanation for this behavior is that Fs for an ESL is determined by its tension and mass of the airload. The mass of the diaphragm is insignificant by comparison. When stacking two diaphragms you double the stiffness, but the mass of the airload is not doubled...it stays nearly the same...increasing by only 30% -35% depending on ESL size/shape and how closely the panels are spaced. If you take measurements while moving the panels together, you will notice Fs increasing as the spacing between them gets smaller. Theoretically, with no space between the diaphragms the airload on the double diaphragms would be the same as for the single panel case and the double diaphragm resonance would increase by sqrt(2) = 1.414.

Last edited by bolserst; 3rd January 2013 at 03:46 PM.
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Old 3rd January 2013, 07:11 PM   #10
john65b is offline john65b  United States
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This is getting intresting. I like the 90 Degree V in corner - will have to see what that sounds like - I want to use at least three panels tho with MK-121 -2A I/F, to ensure descent bass output...
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