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Who is using passive preamps and why?

Seldom has there been any discussions on passive preamps in the forums and although my experience with them has been limited I have found them so far to be very enjoyable and refreshingly different. They seem to fall into their own category, somewhere between solid state and tube. Finding a preamp that is satisfing has been difficult. Some active solid state preamps can be very good but they seem to inject grain to some degree in the upper registers and some tube preamps are not too far behind. So far I think they should at least be matched up with an amp that has sufficient gain which is often overlooked. Which passives are you using and with what amp? Why do you like them?
phd
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herman
2,253 posts
 
Rrog, If you want to say that the overall gain structure of the system must be considered then, yes, in some systems you do need the extra gain you can get from an active so the factors you listed which have to do with how loudly it can play do need to be considered, but that is true no matter what. It isn't something to consider only when you hope to use a passive. Having a system with so much gain that you can barely turn up the volume control is a problem just like turning it all the way up and it not being loud enough is a problem. To say your list is something to consider with a passives and not saying it is something to consider when building any system misses the point and is misleading, they are factors to consider with any preamp since either scenario (too much or too little overall gain) can be achieved with a passive or an active if the rest of the system has too much or too little gain.


Other than how loudly it can play and how much drive to the amp it takes to get there, the factors you mention have nothing to do with whether or not a passive will work well...speaker impedance? In fact you left off the most important factor; the ratios of source output impedance, passive impedance, and amp input impedance.

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almarg's avatar
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almarg
9,670 posts
 
I don't think anyone has mentioned cable length and cable capacitance yet in this thread. Those certainly being factors that need to be kept to a minimum on the output side of a passive preamp. High output impedance into high cable capacitance (which is proportional to length, as well as varying widely among different cables) will result in upper treble rolloff, and long cables will increase the likelihood of other adverse cable effects as well.

Regards,
-- Al
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almarg
9,670 posts
 
Grant -- I'm not particularly familiar with the VRE-1, but I recall that it includes a jfet (active) buffer stage. Assuming that is in the signal path and is followed by a coupling transformer at the output, I'd expect the resulting output impedance to be much lower than in the case of a purely passive preamp. Perhaps that is why the long cable is not a problem for you?

Best regards,
-- Al
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