Acoustat Answer Man is here

I currently have a pair of Monitor 4's using the ServoCharge amps fully rebuilt/modded by Mike Savuto of Analog Associates. Due to space constraints in a new arrangement, I'm looking to convert them to 1+1's or maybe 2+2's.

What if anything is required electrically if I would go with 1+1's and having only 2 panels as opposed to 4?

Thanks in advance.

Bryan

Hi, Bryan.

I have a pair of Mike Savuto modded ServoCharge OTL amps that I have used on Acoustat 1+1s. Nothing was done to the amps to make them more compatible with 1+1s. The 1+1/OTL combination works well and sounds great. The bass, however, is not as full or as deep as I would like. Of course, dipole cancellation and the narrow width of 1+1s are issues, but since the Servocharges were designed for 3 and 4 panel wide Acoustats, I wonder if the circuit eq in the OTLs is not ideal for 1+1s.

Unlike the MK121 interfaces, ServoCharge amps do not seem to have any adjustments for bass except for the following from the manual for the ServoCharge amps:
"R9, R10, C12, and C13 comprise the "wall effect" network to smooth the bass response of the dipole output of the speakers in the presence of an acoustically reflective rear wall. If the speakers are to be operated a considerable distance from a wall, or in "free air", this network can be effectively bypassed by the addition of a 1/2 megohm resistor in parallel with C12."
I have not tried this, however, since I don't like messing with 5000 volt amplifiers.

I recently got a pair of Acoustat 2+2s that I am refurbishing. Eventually, they will be used with the ServoCharge OTLs. 2+2s have enough bass for me while not being too big for my room.

Noel
 
Thanks Noel. I assumed if I converted them to a 2+2 type arrangement, no big deal since I'm still driving 2 9" and 2 8" panels. Was just concerned that IF I decided to do the 1+1 arrangement, I'd have to do something in the panels themselves.

I just have to believe that 2 panels vs 4 panels is presenting a completely different load to the amplifier.

I LOVE what Mike did to the amps. It's a whole different world. I went for the whole hog God Mods. They sound great on the IV's as is. The bottom end just makes people shake their heads. So much for panel speakers not having any bottom end - lol. I believe Mike told me that the resonant frequency of the IV's panels in total is around 24Hz.

I just need a little more space in the room and a little more freedom in how I can space them apart. Going to a 2+2 arrangement will hopefully give me enough. I know the 1+1 will.

If I did the 1+1's, what I'd do is build an IB sub into the floor behind the speakers to augment the bottom end while still being quick enough to keep up with the panels.

Bryan
 
Thanks Andy.
I will try the 4 panels horizontally using the Spectra transformers first and I'll try the Servo charge amps later.Another question, do you know where to get the plastic inserts/ shoulder washers that are used between screwhead and the panel when mounting the panels to the frame.
Thanks
Andrew
 
Hi, Bryan.

I have a pair of Mike Savuto modded ServoCharge OTL amps that I have used on Acoustat 1+1s. Nothing was done to the amps to make them more compatible with 1+1s. The 1+1/OTL combination works well and sounds great. The bass, however, is not as full or as deep as I would like. Of course, dipole cancellation and the narrow width of 1+1s are issues, but since the Servocharges were designed for 3 and 4 panel wide Acoustats, I wonder if the circuit eq in the OTLs is not ideal for 1+1s.

Unlike the MK121 interfaces, ServoCharge amps do not seem to have any adjustments for bass except for the following from the manual for the ServoCharge amps:
"R9, R10, C12, and C13 comprise the "wall effect" network to smooth the bass response of the dipole output of the speakers in the presence of an acoustically reflective rear wall. If the speakers are to be operated a considerable distance from a wall, or in "free air", this network can be effectively bypassed by the addition of a 1/2 megohm resistor in parallel with C12."
I have not tried this, however, since I don't like messing with 5000 volt amplifiers.

I recently got a pair of Acoustat 2+2s that I am refurbishing. Eventually, they will be used with the ServoCharge OTLs. 2+2s have enough bass for me while not being too big for my room.

Noel

Hello frequency response for Acoustat's

1+1s = 30-20k hz plus - minus 2db
2+2s = 28-20k hz plus - minus 2db

I have no problem at all with my 1+1s with a little Chord CPM-2600 integrated amplifier they sound awsome in a 14x23 room.
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Hello frequency response for Acoustat's

1+1s = 30-20k hz plus - minus 2db
2+2s = 28-20k hz plus - minus 2db

I have no problem at all with my 1+1s with a little Chord CPM-2600 integrated amplifier they sound awsome in a 14x23 room.
AndrSystme1600x1200.jpg


Andre, after you put your 1+1s in steel frames, how much did they change in terms of bass response? I bet they do not wobble at all like they do with mdf frames. How much do they weigh now?
 
Plexiglass rear diffusers, anyone used them?

I have similar problems as described here (same speakers, 2+2's):

Acoustat article: Plane wave control mod by Sam Kurutz

Has anyone here tried this solution? The panels are not that expensive and it's easy to do. I'm just interested in knowing if anyone got similar results if they tried it?

Also, if anyone tried it, my speakers are also toed in, do you toe in the plexiglass so that it parallel to the rear of the speaker, or you leave it parallel to the rear wall, regardless of the degree of toe in of the speakers?

Thanks.
 
Andre, after you put your 1+1s in steel frames, how much did they change in terms of bass response? I bet they do not wobble at all like they do with mdf frames. How much do they weigh now?

Hi again noelm, yes the all steel frame helped pretty much for everything the speakers weigh about 200 pounds BUT the biggest difference was with the last two mods that where done Caddock ms-322 resistors & ASC caps soon to be changed again pretty soon will come back on those later ( special made to order caps ) was asked not to discuss until they are inside my interfaces will get back to you later on those, for more info visit my Flickr photo galery here the making of my all steel Acoustat's are there with others, the man behind the mods is my friend Jocelyn Jeanson from Kingsbury Quebec Canada he is the owner of those all steel 600 pounds Acoustat Spectra 6600s he as rebuild many models for a bunch of friends here in Quebec he is like me an Acoustat fanatic except that technically i'm a BIG zero compared to him.

http://www.flickr.com/photos/mracoustat/
 
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I hope that something was done to damp the steel frames??

No doubt that the less frame/mounting motion that there is, the better any ESL sounds... high mass is one way to approach the issue.

_-_-bear

The frames are 2x3 steel covered with glued wood and filled with silice they are DEAD quiet.

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An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.
 
The small ones are my 1+1s and the big ones are my friend Jocelyn's Spectra 6600s the last picture is our friend Serge Model 6s

An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.
 
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Are those big ones 3+3?

I'm not surprised at all that you get a lot of bass without using a subwoofer. If done right, ESL's bass isn't that bad at all. My 1.2 x 0.3 meter panels running full range sound pretty good too. I stop using subwoofers long ago. :)

By the way, what is bybee modification?

Wachara C.
 
Are those big ones 3+3?

I'm not surprised at all that you get a lot of bass without using a subwoofer. If done right, ESL's bass isn't that bad at all. My 1.2 x 0.3 meter panels running full range sound pretty good too. I stop using subwoofers long ago. :)

By the way, what is bybee modification?

Wachara C.

Jack Bybee speaker bullets.

Bybee Internal Speaker Bullets Kit
 
Are those big ones 3+3?

I'm not surprised at all that you get a lot of bass without using a subwoofer. If done right, ESL's bass isn't that bad at all. My 1.2 x 0.3 meter panels running full range sound pretty good too. I stop using subwoofers long ago. :)

By the way, what is bybee modification?

Wachara C.

To me, that's one of the allures of ESL's (done right - full range...). The bottom end is just so fast and detailed compared to pretty much any cone in a box.

Bryan
 
To me, that's one of the allures of ESL's (done right - full range...). The bottom end is just so fast and detailed compared to pretty much any cone in a box.

Bryan

Once you have tasted ESL's there is NO going back at least not for me it as been since 1984 for me always with Acoustat's and i will leave this world before them but will be leaving behind some very happy audiophile.