Balance control

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sbench
Posts: 296
Joined: Fri Jan 28, 2005 3:45 pm

Balance control

Post by sbench »

Follow on from Step1.

Here's sorta question for the group... what does everyone desire in a balance control? Here's my take...

1. Most material is "reasonably" well balanced, so that perhaps a +/- 2 or 3 dB variation per channel is all that's needed.
2. Total level ought to remain about the same.

What this suggests is that perhaps, the simplest balance can be:
Left Right
+1 -1
+1 0
0 0
- 1 0
- 1 +1

which allow a 5 position switch and requires 2 additional taps on
the main attenuator (at the "top" of the 'former). But maybe that's
too naive?

Hmmm. (Steve sez after thinking a bit more) At least one problem exists when tacking this onto the main attenuator. We're out of convenient termination points,,, otherwise we'd put more "taps" on the attenuator.

Well then, since we have "conveniently" conjured up a 3:1 transformer anyway, how about putting a couple extra taps on that to provide +/-1 or +/-1, +/-2 dB output from that xfmr? That puts the "balance" after the amplification, but...

Comments?

Steve
sbench
Posts: 296
Joined: Fri Jan 28, 2005 3:45 pm

Post by sbench »

In case anyone's having a problem visualizing how this would work, the attached schematic may help. In this picture, I have included a balance circuit using only one additional "low turns" winding. This is intended to be such that with the additional winding connected series aiding, the output level increases 1dB, and connected series opposing, the output level decreases 1dB.

The switch then switches in the additional winding as required. This is a sort of "minimal electronic intervention" balance.

Steve
Attachments
bal1.gif
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