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Mono preamps

PostPosted: Tue May 15, 2012 9:12 pm
by edgarryan
A noob question:

Supposing I have two identical mono preamps, would using them simultaneously, with one being the left channel and the other the right, produce a stereo sound? How would the imaging be affected? How different would this set-up be compared to using a single stereo preamp?

Re: Mono preamps

PostPosted: Tue May 15, 2012 10:53 pm
by JackD201
Hi edgar,

If fed L and R respectively from a stereo source, yes they will produce stereo. Theoretically if both channels are matched perfectly they will have an advantage in imaging over a stereo preamp whose two channels share a common power supply. It's the same principle as monoblock vs. stereo amps. There is one huge caveat however and that is, as mentioned, having both channels as closely matched as possible. By that they will have to have pretty much matching tolerances for all parts end to end. Mismatched gain can skew the soundstage and so can distortion. Timing differences will likely be perceived as mismatched gain, as in later will come across as softer with the image pulled toward the earlier or stronger channel. If the two mono preamps don't have stepped attenuators it will also be difficult to set the channel balance with the two independent volume controls. On the other hand two independent volume controls can serve as a substitute for a balance control. Personally I'm used to dual mono preamps and in time anybody that uses them will get used to them too. Just remember the caveat. :) ;)



Re: Mono preamps

PostPosted: Wed May 16, 2012 12:37 am
by edgarryan
Yup, that's what I thought. They should be identical in every way, except perhaps cosmetics, or else the sound would perhaps be like Capitol's Duophonic discs.

Re: Mono preamps

PostPosted: Wed May 16, 2012 4:38 pm
by edgarryan
Follow-up question:

Would it be possible to add outboard volume and tone controls to a pair of mono preamps which don't have them? If it is possible, where should they be placed? Is it like

Source - Control - Preamp - Amp


Source - Preamp - Control - Amp?

If it is the second, wouldn't that decrease the "tubey" sound?

Re: Mono preamps

PostPosted: Wed May 16, 2012 9:11 pm
by yaden
Sir you can add a passive pre amp so you can control two active pre amp

Re: Mono preamps

PostPosted: Wed May 16, 2012 9:43 pm
by edgarryan
Stupid me. The amp I'll use has a treble, bass, and volume control nga pala. I could just use those.

Re: Mono preamps

PostPosted: Thu May 17, 2012 10:14 am
by Gau_Ban
Uhhhhh.. I am puzzled. I don't understand why a preamp doesn't have a volume control. And it sounds like you are connecting the mono preamps to the input of an integrated amp.

Are those mono phono preamps by any chance?

Re: Mono preamps

PostPosted: Thu May 17, 2012 10:20 am
by edgarryan
Yup, mono preamps. I am going to try a vintage tube set-up.