Can I tweak L-R balance by differntial biasing?


My new (to me) Almarro integrated does not have a balance control but my room is slightly asymmetrical. I'm playing a little w speaker toe-in to try to correct this, but I just had another idea. Bias spec is 0.20 volts, with 0.18 volts suggested as a minimum which will reduce output slightly but provide more tube life. It seems to me that if I bias the output tube slightly lower on the "louder" side, it might shift the balance slightly toward the side that is biased higher. Does that make any sense???
128x128Ag insider logo xs@2xswampwalker
Hi Michael,

I'm not 100% certain, but I don't think that approach would accomplish what you want. I believe that gain, which is what you are trying to change, will vary very slowly as bias is adjusted. If you want to unequalize the gains by say 2 or 3 db or more, I suspect that you would have to change the bias setting by much more than the maximum recommended reduction of 10%, even if you were to raise the setting in the other channel by a reasonable amount. That would most likely result in the sonic quality of the amp, as well as its maximum power capability, being considerably degraded.

Best regards,
-- Al
If you have to resort to biasing two channels or two amplifiers differently in an effort to achieve balance, where is the advantage of not having a balance control? It would seem the balance control would be much less intrusive. The other option is a preamp with a left and right volume control.

I think the bias idea is a bad idea. I would try balancing the room by rearranging furniture, window treatment, room treatment or whatever.
Bias has no effect on gain until the tubes begin to approach cutoff.

Reducing the bias will likely increase distortion, assuming that the amplifier design is optimized.

So the simple answer is 'no, this will not work.'
Al- Thx, after thinking about it more, I began to believe that the approach, which would limit the power output, would not have much effect at typical listening volumes, but I do not have the technical background to be sure.

Rrog- If my integrated amp HAD a balance control, I surely would use it. Re-arranging the furniture is not a viable option, it's OUR living room and my wife has compromised enough by having one end of it full of my gear.

Atmasphere- Well, that pretty much settles it ;-) Missed seeing you in NY this past weekend. I imagine exhibiting in NY must be very $$, but the show could have used another good tube set-up. Too many uber-detailed, unmusical, megabuck ss rigs.

All- Sometimes, thinking outside the box is thinking outside reality. Case closed, bad idea. Thx for your help.
I've found that the best way to do accomplish this without a balance control is to move the speakers. You can very accurately, and in whatever incriment you desire, shift the balance just by moving the desired channel either closer or further away. Image is a little shifted right, just move the right speaker 1/2 to an inch further way from you. Try it. You might be surprised how well it works.