Man i did like the sound of the old Acoustat X...even if it was a littel dark sounding...But thay were in a box an canted back....the frist Acoustat i owned back in the 80s... I would not deal with the Sevos i would just add a bias an leve the SevoAmps stock or as thay are...have fun an goodluck
![MK-121C_Xovr[1].gif](/community/data/attachments/249/249463-835ef1b9282f67e5ab2c15b797326720.jpg)
I am not sure if there would be in benefit to separating them ,unless the bias voltage is common to the amplifier plate supplies.
I will have to look up the info as maybe I am thinking of the wrong amplifier system.
jer
The plate supply and diaphragm bias are fed from the same supply, as there is only one high-voltage transformer. Making the two supplies seperate might offer some sonic benefit, plus having the diaphragm bias as a seperate supply does offer the highly advantageous benefit of allowing the panels to remain charged even when the amplifier is in the 'sleep' mode.
The circuit shown above for the MK-121 bias supply should work well. I do see the 750-VAC Acoustat bias transformer for sale on eBay occassionally, and possible other sellers. Part number is TTA-117 for the 110/120 VAC input model. Other transformers with different output voltage could be used by adjusting the number of stages in the voltage multiplier (within reason, of course). So nice to see a schematic that I drew so many years ago, still getting good use. Who knew?
Wow I would think you Knew....An may i say, thanks for some of the best ESLs i have ever had! I know it was jims deal but ...you were there...I have had a lot of esl Quad....SoundLab....MartinLogans ...But thay come an go.......Along with the Magnepans B&W thiels ADS Apogee...Got have one pr of every thing ....Once..But i well die with Acoustat panels in my home.
Thanks for your time an the info on Acoustats thay just keep going an going..
Thanks for your time an the info on Acoustats thay just keep going an going..
Wow...that's the nicest comment I've heard all week. Your comparison of Acoustats to all the other manufacturers is a very strong testimonial, and there isn't much I can add to that! Acoustats do seem to just keep on running year after year, and that is one of the reasons I spend time helping owners maintain their speakers - because both the speakers and their owners deserve it! I also try my best to erase the ill effects of Rockford's bone-headed move (IMHO) in selling the brand to an Italian firm. I truly believe that a US buyer could have been found, and if that had been the case, I believe that Acoustat would still be a strong contender in the market, and would still offer support to the thousands of speakers still in service. And who knows, I might still be enjoying the most rewarding job I ever had. What a shame! Color me bitter? - you bet!
I too, will die with my Acoustats!
The Model X with servocharge amplifiers are still in demand. The hardest part of selling a pair is finding the buyer in the right time and place, since shipping is usually not a viable option. I do watch the Acoustat items on eBay, and see Model X's selling, even if it takes a few re-listings before the right buyer is found. Price will vary a lot based on condition, and how recently the amplfiers have been reconditioned. I would expect to get something in the range of $1000-2000 USD per pair, but a really nice pair might go for more if the bidding gets crazy. I would suggest setting a reserve price to make sure you get the minimum amount you want. Good Luck!
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