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Edward Morris Edward Morris is offline
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Default RCA shorting plugs

Hello,
I have a C22 preamp and it has RCA shorting plugs in the Phono 2 inputs,
the Tuner 2 inputs, the tape head inputs and the MIC inputs. Are these
shorting plugs necessary and should they be used in all unused RCA inputs
jacks?

Thanks for your help,
Edward

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Peter Wieck Peter Wieck is offline
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Default RCA shorting plugs

On Dec 10, 12:46*pm, "Edward Morris" wrote:
Hello,
* * I have a C22 preamp and it has RCA shorting plugs in the Phono 2 inputs,
the Tuner 2 inputs, the tape head inputs and the MIC inputs. *Are these
shorting plugs necessary and should they be used in all unused RCA inputs
jacks?

Thanks for your help,
Edward


They *should* be used on any head-amp input (tape head, mag. or MC
phono).

There is no reason *not* to use them on other inputs.

Peter Wieck
Melrose Park, PA
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Patrick Turner Patrick Turner is offline
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Default RCA shorting plugs



Edward Morris wrote:

Hello,
I have a C22 preamp and it has RCA shorting plugs in the Phono 2 inputs,
the Tuner 2 inputs, the tape head inputs and the MIC inputs. Are these
shorting plugs necessary and should they be used in all unused RCA inputs
jacks?

Thanks for your help,
Edward


Its a good idea to leave them all plugged into inputs you don't use.
They keep the inputs to the amp all biased to 0V and keep the noise low
if you switch to the grounded inputs. Grounded inputs do *no harm*. And
the sockets are sealed to keep out dust and pollutants that pile up
inside vacant RCA sockets to cause poor connections in future.

Patrick Turner.
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Jim Gregory Jim Gregory is offline
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Default RCA shorting plugs


"Edward Morris" wrote in message
.. .
Hello,
I have a C22 preamp and it has RCA shorting plugs in the Phono 2
inputs,
the Tuner 2 inputs, the tape head inputs and the MIC inputs. Are these
shorting plugs necessary and should they be used in all unused RCA inputs
jacks?

Thanks for your help,
Edward


Such shunt plugs are inserted only when needing to -measure- noise
self-generated from a particular pre-amp stage, especially mics.

A v good Mic hum + noise figure would be 62dB lower than a usual active ref
programme level of 1mW at pro' line output. Possibly a lower o/p level on
domestic circuits. Not sure about the datum found in a McIntosh design.

But noise figures in gram PU and tape-head circuits are sloped, frequency-
dependent because of frigged equalisation curves in the AF band either side
of 1kHz.
When evaluating a stage's quality, the shunt resistor should not be zero
Ohms but ought to mimic the source impedance of the -relevant- transducer.
I.e., 'dynamic' mic evaluator should be a 150r to 200r low-noise MO
resistor - to simulate a muted! mic.
Jim



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BretLudwig BretLudwig is offline
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Default RCA shorting plugs

Mc being Scottish would not have provided them if they did no good. Keep
them.

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