Relocating power switch and inputs to rear

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Relocating power switch and inputs to rear

Postby Hewie » Mon Feb 02, 2009 5:36 pm

Hi all-
I would like to move the R&L input jacks from the front of my ST70 to the rear, and also move the power switch from the rear to the front as I see some people have done. Are there any guidelines I should adhere to about relocating these connections? How did you route the input leads and AC line to avoid hum/noise?
Thanks ahead,
Dave
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Postby burnedfingers » Fri Feb 06, 2009 5:48 am

Dave,

I'm going to give my .02 and you may not care for what I am going to say. To move the inputs away from the board doesn't make too much sense because you will be inviting unwanted noise into your amplifiers input stage. I'm not saying that there isn't a possibility that it can be done however. If you are bent on doing it then beg or borrow some mic line with a twisted pair and shield and try that. Add on and route away from HT lines as to minimize interference. Do not drill holes in the chassis yet until you can get it noise free. If it were me I would leave the AC lines alone and where they are at but you want to move them. I would try a relay and activate it from a switch in the front of the chassis. Again no holes until you find out if it will work without a noise issue.

Others may have a better idea of what might work :)
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Postby Brik » Fri Feb 06, 2009 8:45 am

burnedfingers wrote:
...Add on and route away from HT lines as to minimize interference....
Others may have a better idea of what might work :)


The magnetic field strength (as opposed to electric field strength) around a current carrying wire is proportional to the current it carries. If it is 50Hz-60Hz hum that you are concerned about, the heater wiring with its relatively high current is the one you want to separate your shielded input wiring from.

For example, the heater wiring to a pair of KT88 would carry 3200mA of AC current as opposed to the B+ wiring which might carry under 200mA of regulated DC current with minimal ripple. I would be more concerned about the heater wiring.

/b
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