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I used to think passive preamps were superior to active preamps given right the setup, but

my recent evaluation of a modded old SS preamp has me a little befuddled.  I've evaluated $10K+ active preamps in the past and was never impressed especially given their cost.  In general, I've found passives to do better job. I know there's ongoing debate on this.  But here's a very illuminating video on the subject by Bascom King, one of the legends of high end audio.

https://youtu.be/HHl8F9amyY4
dracule1
auxinput
2,920 posts
 

On the argument that passive is better/worse than an active preamp, just keep in mind that the preamp is just another piece in the audio signal line that his helping shape the sound.  Even a DC blocking signal capacitor in a passive preamp can shape the sound somewhat when the capacitor charges/discharges the audio waveform as it passes through.

As far people who like their passive preamps, it really depends on the sonics coming from your source.  So many DACS/sources can still have that digital type square waveform sound that lacks bass and can be thin.  In this case, a great tube or Class A preamp can really help things.  If the source is tube based or has multiple Class A circuits that are filtering/shaping the sound from the DAC chip, a passive preamp may sound better than an active (depending on equipment choice / synergy).  I describe some of this effect in this post here:

http://www.diyaudio.com/forums/digital-source/292574-do-i-really-need-high-slew-rate-opamp-output-my...

A tube or Class A preamp can help further shape this waveform.  It can actually translate more bass from the original DAC waveform and may even give you more midrange body and overall better volume.  Things may sound louder.  On the other hand, a very "solid-state" non Class A preamp may just attempt to reproduce the sound waveforms exactly as they entered the preamp with little or no shaping.

paradoxent's avatar
paradoxent
13 posts
 
I do not normally get in on these type of conversations but the facts are everyone is correct.
Passive is the best interface sonically, least parts to hurt the sound.
BUT
If the device cannot drive the load (input impedance) of the next device (usually amplifier) properly then a preamp or a product with current gain is necessary to drive the input load and get the best sound (performance) of the device being driven.
To overly simplify one product drives the next if you do not have enough voltage or current than passive will not sound as good.
hapinoregon
4 posts
 
With regard to Nelson Pass' commens

I have a 1996 version of his Pass Labs Aleph P preamp that has separate controls for gain and volume. His advice was to set the gain as low as you can and the volume as high as you can for your basic listening and use the remote to adjust the volume.

I've gotten the up-grade itch several times, but have yet to find anything I like better. Amps and speakers have changed but the Alpeph P has been a constant.
doak
199 posts
 
To be totally successful in using a passive-pre the rest of the system must be built/chosen with the accomodation in mind. This doesn't really require compromises IMO since the things that work best also make for a better system.  In such a case gain can only be detrimental to the sound since any active device with gain will also surely add colorations to the sound.
I've been using the passive approach most of the last 30 years.  For the last 15 it's been TVC/AVC based devices. I've occasionally tried promising low gain active designs up to $5K but have always come back to the TVC's purity and quietness. 
georgehifi's avatar
georgehifi
10,312 posts
 

All the above 5 post have valid statements, the best preamp is no preamp, this is closest to a straight piece of wire sound.

Source direct or through a simple direct coupled passive is the most transparent/dynamic way of hearing the source. 

You may not like the sound this way because your hearing the source for what it is, does this mean you add an active preamp to colour that sound hopefully in the right areas or get a source that doesn't need to be coloured?

Cheers George     

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