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Re: RCA/Rozenblit RIAA Line Amp idea

83.248.127.182

Posted by Pär on August 15, 2006 at 13:23:30

In Reply to: Re: RCA/Rozenblit RIAA Line Amp idea posted by shermanr@prw.net on August 15, 2006 at 13:00:10:

Hi,

> /.../a small DPDT switch and select either a 1 meg direct or a 250 Ohm variable potentiometer.
Just to avoid noice and failure do not run the tube without any resistance on grid curcuit. So have the 840kohm - 1meg there all the time and put the switch between the pot and the "bleeder".
[IMHO]

> Is there a maximum length for the umbilical cord that joins the
> two boxes together that carries the B+ and the 12 VDC?
> I was thinking about maybe 1m long maximum.

For B+ there is no real problem, given properly isolated cord, more than it may pick up noics, but some filtering capacitance at the preamp side would cure that. Do mind the connectors so that there is no possibility of touchable pins (when connector removed) with B+, and connectors that cope with your B+ (harder to find than the cord).
[IMHO]

For 12VDC it is more or less just to find a cord that dont give to much voltage drop given the current. The voltage is "harmless" and any picked up noice wouldn't hurt anything.
[IMHO]

IMHO added as we are getting into personal preferences and practice here :-)

mvh /Pär

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