MartinLogan Bias Mod

[tyu]

Look at the Zeners,Bottem righ....
This what sets up the Bias,it at allmost 5500-vWith out the Zener string
Reg.to ground.

If you go up to much with the ML panels, You hear a buzz, just back off.Same as my Soundlabs you here the buzz back of a little...

Mr Powers gave Me the info...an i did this MOD, it works...As you see ....Eze..


As you see there are two RE. r23-r24 1.8k in the feed to the bias tranfourmer on the AC side....this well give more aswell, Just jumpr23-r24 an you go to allmost 4000-v.. From The stock of 3700-v....Have Fun Price$$$$ your time.

[tyu]

I have bypast the SL3 bias board .
Put in the Ajustabl bias for my Acoustats, now i can go from 3.5k to 6.5k Thay now can be set up to mach the bass driver much better an there at 4.3k sounds better than ever.
One thing the bias add too the sound of the panel.... Most dont talk about this,so the by-pass cap mod can help tune the tone...mod is to go from ground to the end of the diode string be for the 50m re. that feeds the panel...Cap .01 5k...or higher

[tyu]

I have dropet the 50m to 6m sounds better.....An have added 2more caps an 2more diodes.....i have found the Acoustats stock bias boards are off now that there 25-30years old...Or the panels or diff.
In my setup i have add a new bias tranfourmer at 1100v before the diodes the stock Acoustats are at 7500v....
Thanks for the Pix.... lzzy wizzy Audio...looks like something i would do if i could....an thay say i am a acoustat nut...Moray J. may give us his Chok mod...cant find?

[moray james]

most of the good stuf is all right here see the link. Best regards Moray James.

Acoustat Tweaks

[tyu]

Look at the SL3 power sip... R21-R25.....these are 15m ohm X4 60m........this panel is 12"x48".....these need to be replaces....thay are 1/4w....i have went to 1ea 5mohm.. 5wat there..sound is much faster... a it look like that going from 3k bias to 3.5-3.7/5...is the sweet spot...but the stock bias tranfourmer in the MLs is about a 1amp.....i have put a 8amp.... what a big diff...same bias-v...sounds 3db louader....Bass starts at the top...
One sided bias feed there still useing....sale them panels..
But these ML are a steal....panels can be Diyed... an the powtercating can take 5kbias...eze Here a Panel with two bias feed FIX..

[tyu]

Just got these of CL for $100.US.....i well have pix after there playing.. there out there the panles are like new....after a bath...here how thay lookt in the add...This is killing my diy ESLs.....

[tyu]

Here the best way to opnen up the sound of the panels on the logans....On the power/bias board...Run a wire from in front of the jumper to r25 this leves r25 with a 15mohm an well sound like new panels.New Day for the older....ML

[tyu]

Well as time gos by thing change....we no this but.....Look at this setup here now...thay have tied all the setup thransfourmer outputs AN THE BIAS FEED FROM THE BOARD..to the panel with the AC..comeing in from the the manes..120ACv...Noise any one.....get that out for better sound...an look at the panel feed on top of the tranfourmer....that only rated for a 1kv...it drops the bias feed DOWN by about 500DC V....it should be 3500-v..not 3000....just moveing that well give better sound!

[tyu]

All i have to do is find grills....or make some....with the bias feed up were it shoued be, the 50watt tube amp drive them well.

[tyu]

Rob... pix...are here...thanks