• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

signal wiring

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I just got in a EICO HF 81 I bought off ebay. I plan on removing alot of the extra selector stuff so the amp has only phono and 2 aux inputs. I noticed that the person that assembled it has twisted the signal wires together that run from the selector switch to the balance controls. I realize that this is a very basic question but this seems wrong and I searched and could not find anything on basic signal path wiring. I would appreciate it if anyone knows a good reference on audio amp wiring.
Thanks
Steve
 
I don't know about the EICO HF 81, but generally twisting a signal and ground wire together is sometimes done to reduce hum pickup.
Twisting the L & R channels together is inadvisable as it can lead to crosstalk if the impedance is high. Sometimes things like this are done for practical or cosmetic reasons rather than for performance. In other words they found it didn't affect performance, so just did it to keep thing tidy.
If you have unscreened signal cables the best bet is to tape or secure them close to the chassis, keeping them away from other components and wiring. Screening the cables will not necessarily give you better hum rejection than taping to the chassis, and can lead to other problems.
 
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