combining 2 sets of 2+2's

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Hi, Would it be possible to run 2sets of 2+2's off of one amp?
1- The amp will double from 200w to 1600w peak at 100a
2- was thinking of series hook-up where neg of one interface would be hooked to pos of other, this would raise impedence, as oppessed to biwire which would have the impedeance. What are your thoughts on this? Or should I forget the idea? Thanks Al
 
Hi, Would it be possible to run 2sets of 2+2's off of one amp?
1- The amp will double from 200w to 1600w peak at 100a
2- was thinking of series hook-up where neg of one interface would be hooked to pos of other, this would raise impedence, as oppessed to biwire which would have the impedeance. What are your thoughts on this? Or should I forget the idea? Thanks Al

It was always Acoustat's recommendation (as well as my personal advice) not to parallel two interfaces on one amplifier channel. The impedance of one interface can dip below 2-ohms, so paralleling two interfaces will yield an amplifier load of less than 1-ohm. That's bad news for most if not all amplifiers.

An even worse idea is to series-connect two interfaces. Each speaker will be presented with only half the voltage swing from the amplifier, greatly reducing the acoustic output. You will also ruin any damping factor that your amplfier provides.

So, my recommendation is that you need four channels of amplification...there's just no way around the problem. Even Acoustat's legendary Models 6 and 8, which used two interfaces per speaker, were intended to be driven by four independent channels.
 
I would not consider doing what you suggest. Acoustat's challenge most amps as it is even big balls to the wall amps and you would be looking at a minimum impedance of just over an ohm, most amps will not be impressed. Just because you have an amp which will drive 3/4 of an ohm does not mean it will sound good doing so there is no point in this exercise. Any amp that could drive such loads that I ever heard did not sound any good doing so. Just because you can does not make it a good idea. They are yours to do with.
When was the last time you ran that amp of yours into less than an ohm? If it has been a good long time I would questions the supplies ability to safely do so now unless it has been updated. Just an after thought. Good luck with this. Best regards Moray James.
 
So you say..... The amp will double from 200w to 1600w peak at 100a

... Tell us about this amp.... Never seen one yet....maybe on paper.... But if you dont Drive the amp too hard....you well get sound...
It was M6s i gess i saw...So minny Acoustats an so littel time....Long live Acoutats...good luck
 
Is this a stock 121-2a with medalion transformers? Can't believe how clean it is, I bought them new in 1983.
 

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Yes it is A, an from my work on the 121 it is the best..No crossover....all amps to day can drive with ezz,,,,
How ever it the bias that i have found to be the bigest setback today...
I have found that when the base tranfourmer...get driven hard buy a big bass note...it so clost to the bias...you can see here it in your pic... can an dose pull the bias down...makes the panels harder too drive.... Amp get hot...
At one time i thought that adding diodes to the bias setup put it back up to the 5k an it dose...but the bias needs to be outboared ..i have done this an set the bias up so you can set it youself. from 5-7k....this brangs the Acoustat up to todays real would ESLs...i put a new bias setup anginst any ESL...SoundLabe...you name them i had most.....After all a ESL is only as good as it bias an panels an jIM GOT THE PANEL RIGHT...
you can see the B type has a crossover on the high frc.trafourmers input ...An C adds even more crossover in front of the sound like 16 ohms 50watt............ some say it better...but to MY EARs... it just a Fix for the amp driving the ESL ezer....today it not needed....................good luck
 

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Moray
can you give us a littel more info on you shilding?....look like to me your setup would pull even more of the power off the Mixer board??
.
What i have found on the 121 Acoustats interfaces....
1.If you are going to move the wires or tranfourmers around... primary or secdary like just pull a tranfourmers you better put hot glue on the wires at paper on the tranfourmers... the wires can move around an can come lose... the wire is stiff an the paper is vary dry...you can kill a tranfourmer...you can see in the pic...the extra Acoustat tranfourmers...have all been hot glued.
If you put hot glue at the paper were the wires come out this stop any movemint..an can stop arking also right at the transfourmer...
2.On the bass an high frc tranfourmer... secdary side all the wires ...can have pin holes in them...an arck all around in the interfaces...an pull the output down.. a lot but not these wires have what was clear tubing this can pull down HV all so.. thay can get wet in side..30years bild up...put new tubing
3. The 50k100 w res. on the miXer board can. have crakes in them ....An ark an pull down output..you can see these crakes some times
4. The Caps on the mixer board 0.1 5k.....when the bias gets pulled down
can get holes in them an ark an pull down output..After all these pars are Over 30years old....
5. An yes the bias.. all the parts need to be upgreaded to new parts..
an if you wont to get the most out of the Acoustats outboard the bias.. it being just 1" away from the driver tranfourmer on the mixer board...at best now all these years later were only geting 80% of what these ESL can do....An seting up the bias so you can set it...4-7k you well get the best out of Acoustat panels have even after 30years...Get right up there with SoundLabs. an other over 10k ESLs..good luck..

I got my frist pr of Acoustats in 1986...Xs with the Servo tube amps....i call jim strickland ...i was freak out.. i told him i had got a pr of the Xs an that if i sat in the dark an drove the Xs hard... the wires in the panels gloed to the beet of the sound... he said that that was nom...so dont think there is not a lot of High V going on here...after time any thing will brack down...but the Acousrtas are still trucking..

Hohoho too all...have a good one


good luck
 

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My gawd, I almost had a heart attack when I looked at the price of each Duelund cap for the imput on HF, awful price to remove a bit of sizzle on some high frequencies, There's got to be a respectable way a getting around the cash gougers and still have quality components. Al
 
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