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Old 23rd March 2017, 05:36 AM   #11
gnnett is offline gnnett  Australia
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The Celestion 6000 sub woofer for the SL600 was a bipolar, back to back dipole arrangement, or was this an open isobaric dipole arrangement as Winrex describes?
Cheers
Grant
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Old 23rd March 2017, 11:25 AM   #12
WrineX is offline WrineX  Netherlands
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Ok there is some confusion now if the panels are back to back and wired normally one membrane would be out of phase. this would result in crap sound overal especially down low. if you reverse polarity of one panel (back one) the membranes are IN phase since one of the panels is the wrong way around.

with back to back one needs to be out of phase, and the back panels should only be fed frequencys lower then half a wavelength distance to the front membrane (after that the the 2 panels will cancel each other instead of adding).

so for instance if the panels are 30 cm apart membrane to membrane, 344/0.3 meter = 1146 Hz divided by 2 to get half a wavelength is 573 Hz. the back one should not produce anything higher then 573. in this way you gain 6 dB under 573 Hz. if you would let it play fullrange you wil get out of phase material lowering the output at a full wavelength around 1146 and form a comb filter from there and up. so many dips and peaks.

since these panels are already eqed for the rise of 6dB for each octave the only usefull thing would beto see where it drops in the low end and and let the back panel play in this range so it can balance the low end and gives you some more Oempf (as a sub). or do all the eq/sengelentation from scratch to create a flat response.

Last edited by WrineX; 23rd March 2017 at 11:31 AM.
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Old 23rd March 2017, 07:48 PM   #13
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Originally Posted by WrineX View Post
Ok there is some confusion now if the panels are back to back and wired normally one membrane would be out of phase. this would result in crap sound overal especially down low. if you reverse polarity of one panel (back one) the membranes are IN phase since one of the panels is the wrong way around.

with back to back one needs to be out of phase, and the back panels should only be fed frequencys lower then half a wavelength distance to the front membrane (after that the the 2 panels will cancel each other instead of adding).

so for instance if the panels are 30 cm apart membrane to membrane, 344/0.3 meter = 1146 Hz divided by 2 to get half a wavelength is 573 Hz. the back one should not produce anything higher then 573. in this way you gain 6 dB under 573 Hz. if you would let it play fullrange you wil get out of phase material lowering the output at a full wavelength around 1146 and form a comb filter from there and up. so many dips and peaks.

since these panels are already eqed for the rise of 6dB for each octave the only usefull thing would beto see where it drops in the low end and and let the back panel play in this range so it can balance the low end and gives you some more Oempf (as a sub). or do all the eq/sengelentation from scratch to create a flat response.
Perhaps reflections off the back wall are somewhat skewing the true effect? All I know is what I hear. I've spent a good deal of time A/B ing the different possible combinations. I keep arriving at this one as the best. I suppose it's possible the interfaces/OTLs are wired internally with opposite polarity normally. That could explain why it's best with the interfaces in phase at the outputs.
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Old 23rd March 2017, 08:25 PM   #14
tyu is offline tyu  United States
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If the back panels are wired in phase....then what sound comes off the back wall would be out of phase with the front...right...
But I have owned the servos amps an thay have pos-neg amp input....it a high/low type setup ...with RCAs inputs also.. that can be used from the preoutputs from preamp also.....but what is the preamps phase?? Not sure about the servos....but I would think its the same as the 121 interfaces .
But this dose not matter....if it sound good it got be right...well to me anyway
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Old 23rd March 2017, 08:33 PM   #15
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If the back panels are wired in phase....then what sound comes off the back wall would be out of phase with the front...right...
But I have owned the servos amps an thay have pos-neg amp input....it a high/low type setup ...with RCAs inputs also.. that can be used from the preoutputs from preamp also.....but what is the preamps phase?? Not sure about the servos....but I would think its the same as the 121 interfaces .
But this dose not matter....if it sound good it got be right...well to me anyway
Yeah, the Oppo direct with the OTLs and the Meridian 501 with the interfaces may collectively be out of phase. But I know what out of phase sounds like and this is not it.
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Old 23rd March 2017, 09:50 PM   #16
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Originally Posted by WrineX View Post
Ok there is some confusion now if the panels are back to back and wired normally one membrane would be out of phase. this would result in crap sound overal especially down low. if you reverse polarity of one panel (back one) the membranes are IN phase since one of the panels is the wrong way around.

with back to back one needs to be out of phase, and the back panels should only be fed frequencys lower then half a wavelength distance to the front membrane (after that the the 2 panels will cancel each other instead of adding).

so for instance if the panels are 30 cm apart membrane to membrane, 344/0.3 meter = 1146 Hz divided by 2 to get half a wavelength is 573 Hz. the back one should not produce anything higher then 573. in this way you gain 6 dB under 573 Hz. if you would let it play fullrange you wil get out of phase material lowering the output at a full wavelength around 1146 and form a comb filter from there and up. so many dips and peaks.

since these panels are already eqed for the rise of 6dB for each octave the only usefull thing would beto see where it drops in the low end and and let the back panel play in this range so it can balance the low end and gives you some more Oempf (as a sub). or do all the eq/sengelentation from scratch to create a flat response.
To your point, it is from lower mid range down that I hear an additive effect. But with that I do hear a loss up higher. The Monitor 3 by themselves is where I hear the flattest response. Which makes me wonder if I should build a structure to enable an incremental adjustment much closer to the front panels. What direction would response likely take? Right now they are 36cm apart. Can I expect a linear change in response with distance?

I love the flat response but I really like that strong enhanced presence.

Last edited by Discopete; 23rd March 2017 at 09:57 PM.
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Old 23rd March 2017, 09:57 PM   #17
tyu is offline tyu  United States
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One thing ....people that have not heard the Acoustat D/d servo tube amps...even the stock amps with old tubes.....an only heard the 121 interfaces....I would say they be shocked......by the Big tone tube magic.....that can come out of these old panels..
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Old 23rd March 2017, 10:28 PM   #18
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One thing ....people that have not heard the Acoustat D/d servo tube amps...even the stock amps with old tubes.....an only heard the 121 interfaces....I would say they be shocked......by the Big tone tube magic.....that can come out of these old panels..
Honestly, I think they give anything a run for the money regardless of price. You have not heard ESLs til you've heard them driven directly.

Remarkable difference between the Monitor 3/Model 3 with and without interfaces/DD OTLs.
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Old 23rd March 2017, 10:48 PM   #19
tyu is offline tyu  United States
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Today I am running a pr of Model 4s on there 121-a with new bias caps an diodes...
with a 20 watt tube amp....an it sounds great....
But these 4s with a pr of re-worket servos amps.....WoW....... for what $18-2500 a pr can be had...an thay will work with any ESL....just working on putting my last ML CLS panels..... Pure Copper Charge-Diffusion Ring on the mylar....love to hear the CLS panels on the servos...
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Old 24th March 2017, 12:50 AM   #20
Steve M is offline Steve M  Australia
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Disco Pete: Rob MacKinlay of ER Audio here in Australia was developing a dual layer stat panel along the principles of what you have jerry rigged with your Model 3 set up. He told me at the time it had great potential to strengthen the sound field of stats and give a positive result in the manner you are describing with yours. Not sure Rob proceeded with the concept though? It was a few years ago we discussed all of this ...

Cheers,

Steve.
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