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From: caseyng@cie.uoregon.edu (Kong Ng)
Newsgroups: rec.audio.high-end
Subject: Re: Passive Preamp
Keywords: passive preamp
Message-ID: <1990Mar21.213143.15193@cs.uoregon.edu>
Date: 21 Mar 90 22:33:56 GMT
References: <9003170016.AA25031@psyche.mit.edu>
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Reply-To: caseyng@cie.uoregon.edu (Kong Ng)
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In article <9003170016.AA25031@psyche.mit.edu> jacob@psyche.mit.edu (Jacob Feldman) writes:
>I am also very curious about the by-passing of the gain stage on high
>level sources. I have a PS Audio 4.6 which has the bypass option (only
>the volume control is in the circuit). Common sense (echoed by many 
>salesmen as well as the PS Audio literature)  seems to suggest that avoiding
>the gain stage can only be a good thing, as you avoid any colorations
>that it might introduce. However, my experience has been to the contrary:

hi,
	Using passive preamp means that you're giving up a buffer stage, say,
between your CD player and power amp.                  
	The output impedance of an active preamp is in the vicinity of 100 ohm,
while the input impedance of the power amp is >10k ohm.  However, with
passive preamp, the output impedance is rather high, due to the volume
control (potential meter) that is usually 10k ohm.  At this point, the         \impedance matching between the passive preamp and the power amp becomes a
problem.  
	I am using a passive preamp for about 2 years. Careful attention to
interconnects helps a little.  I haven't compare my passive preamp to some
great preamps, but it outperforms budget preamps <$500.  The main advantage
of the passive preamp is its transparency, natural timbre, and soundstage.
However, it lacks dynamics and a pulpable bass.

casey