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Passive & Tubed pre-amps to power amp at same time?

Would any harm be done by using a Y-splitter to simultaneously connect a passive pre-amp and tubed pre-amp to the same power amp? The idea would be to use the passive for volume control and run signal from a CDP to the power amp. The tubed pre would be used for sending other inputs (e.g., phono) to the power amp. All devices would be "powered up" at the same time but only one input at a time would be used. Thanks in advance.
ghosthouse
ghosthouse's avatar
ghosthouse OP
3,718 posts
 
Zd...no volume control on the CDP. It's 2.6 Vms out unbalanced and 4.6 Vms balanced. That's why I had been thinking to skip the tubed pre-amp and go passive with the Schiit SYS.
georgehifi's avatar
georgehifi
4,966 posts
 

If I get this right with what you want to do.

What I would do is put all your sources into the inputs of the active preamp so you can switch between them, then come out of the tape output of the active preamp into input of the passive preamp and then out of the output of it to the poweramp/s input.

Basically this way your using the active preamp as a source selector.

Cheers George
ghosthouse's avatar
ghosthouse OP
3,718 posts
 
Thanks for the idea George. What I am trying to do is introduce volume control
for the CDP without any addition boost in gain while leaving other sources
unaffected that run through the tubed pre-amp. Your idea does seems like
something to explore. No tape out...but sub out. However, I am going with Al's
suggestion of attenuators. Ordered a couple of Harrison Labs -12dB RCA plugs
from Parts Express. Much less expensive than those from Rothwell and Parts
Express allows returns if they don't work out. Others on A'gon do report
satisfactory results using these. Thanks again to all for the suggestions.
ebm
5,165 posts
 
Very bad idea splitters are bad quality.
almarg's avatar
almarg
8,673 posts
 
Ghosthouse, if you happen to have a multimeter it would be interesting to know the values of the two resistors that are presumably used in the Harrison Labs attenuator. The values aren't particularly critical, but knowing them may provide added confidence in their suitability for the application.

You would take two resistance measurements, one between the input center pin and the output center pin, and one between the output center pin and its ground sleeve.

I've measured those values in the Rothwell 10 db attenuator as 22K and 10K respectively, which seem like reasonable numbers for most (but not all) applications. Especially, as in your case, when used between a solid state signal source (presumably having low output impedance) and the input of a tube-based component (presumably having high input impedance).

Also, thanks very much for the nice words. Best regards,
-- Al
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