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Eliminating balance controls on Eico st70

Dlav

Member
2014-02-18 12:28 pm
Louisiana
Hello to all, I'm considering to remove the balance pots on my Eico st70, and going with separate volume controls left & right channels I've attached the portion of SAMs photo fact at the section of balance and level controls. I can follow a schematic, change out parts if needed, I can not design. I know I'm asking for a lot here. If someone can explain to me what has to be done, like the resistance value of the balance pots still need needs to be I front of the new volume pots, where to break circuit and where to insert the wiring. I want to use dual step attenuator, do they need to be the same resistance as original?
Thank you for your time and assistance if possible.... David
 

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rayma

Member
2011-04-29 8:37 pm
Hello to all, I'm considering to remove the balance pots on my Eico st70,
and going with separate volume controls left & right channels

This should be simple enough. Remove the balance and volume controls,
and install the two 250k mono stepped volume controls in their places.
The input to each volume control is the center contact of that channel's
tape monitor switch, through a 360k 1% resistor.

The "wiper" of the new volume control goes directly to the grid of the line amp's input tube.
Unless you want to use the loudness control, I'd remove those parts and connections.
Otherwise you can connect the loudness circuit to the 25k point on the new controls.
 
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