Balance control on autoformer

discussion of magnetic volume control design for both line and speaker levels.

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Rickster
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Joined: Wed Jul 24, 2019 8:29 pm

Balance control on autoformer

Post by Rickster »

How does the balance control work on the stereo 23 position autoformer with balance control? Is there a schematic available?

I also am curious how the two switches interact on the auto former modules? How many taps are accessed on the autoformer? Are any resistors used to perform the fine attenuation of the second switches?

Thank you,
Rickster
dave slagle
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Post by dave slagle »

The 23 position with balance control has 2.5dB steps for the left and right adjust knobs. The center knob simply cuts or adds 1.25 dB to one channel or the other by selecting a different input point to the autoformer.

so if the L and R are both set to -10dB and the center knob is clicked 1 click to the left, the left will now be at -8.75dB and the right will remain at -10dB. Another click to the left and the left will remain at -8.75dB and the right will go to 11.25dB netting a total shift of 2.5dB to the left. A similar result could be had by simply clicking the left channel down 2.5dB. Whatever the setting that gives proper balance, it will remain the sam as long as the left and right knobs are changed the same amount.

there are no resistors at all used for attenuation or balance

dave
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Rickster
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Joined: Wed Jul 24, 2019 8:29 pm

Post by Rickster »

Thank you, Dave for such a clear response. That appears to be quite an elegant solution. I am in the early stage of planning my next project, but I am very interested in including your AVC.
Thanks again.
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