2. amps-preamps
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Bypassing A Preamp With Volume Pot In Amp

I see preamps as a convenient tool to control the volume of multiple sources. It only adds another link in the chain. It also adds to the cost of your system because you will need other pairs of interconnects and a power cable.

I was thinking about completely bypassing a preamp by adding a volume pot or a resistor based stepped attenuator into the amp, greatly reducing the signal path from the source to the amp.

The only detriment I can think of, is switching the interconnects from each source which is as troublesome as switching out a disk from the CD player.

Please chime in with your opinions and especially your experiences with this "issue".

The volume control I have in mind is the Khozmo stepped attenuator using 2 Vishay TX2575 resistors in a hybrid tubed/ss amp.
c_avila1
atmasphere's avatar
atmasphere
7,068 posts
 
If you have the control installed in the amp this works quite well. Switching the interconnects will get old after a while though.
georgehifi's avatar
georgehifi
4,966 posts
 
C_avila1: Great idea, if your source has equal or higher output voltage than the input sensitivity of your amp great, you are almost there.

If your source has a nice low ouput impedance say below 100ohms, this will happily drive down to 1kohm (1:10 ratio).

EG: The combined load of say a 10kohm passive and a 47kohm input impedance (industrie standard of most amps)amp is still 8.2kohm, the 100ohm source will happily drive this (1:82 ratio), then this will be the most transparent/dynamic sound you will get.

Cheers George
ptmconsulting
1,000 posts
 
Sounds like a DIY passive preamp. Why not get a selector switch and a few more RCA's and avoid the plugging and unplugging of the interconnects?
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