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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
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
Interesting that Bascom King points out a couple times that 'intellectually' wise he really wants to like the sound of passives better, and direct to amp better.
It must be difficult from an engineering mindset to let oneself relax and actually listen to music without trying to analyze components.
Many engineers cannot grasp a lot of the concepts that audiophiles enjoy, as they cannot make intellectual sense to them.

As for myself, I tried 3 passive preamps about 15-20 years ago, and realized early on that a passive could not compete with a good active tube preamp to my ears.
Looking back, I did not perform these trials with tube sources and tube amps, so that could have some affect on my results.
bdp24's avatar
bdp24
9,788 posts
 
Curious that Bascom didn't mention another engineering fact of passives, that of their output impedance. The output impedance of passives varies with the setting of the volume control, often to a figure too high for the input impedance of some power amps. Also, interconnects must be kept short between passive pre and power, so mono amps behind the speakers are out. And if you want to bi-amp your speakers, that is not possible with many passives.
georgehifi's avatar
georgehifi
10,312 posts
 

Sounds cynical I know, but he is selling his latest BHK Preamplifier design through P.S. Audio. Why wouldn't he say this now, and not back then when he probably heard much better as well. This clip doesn't convince me one iota.

For the ultimate transparency and source signal transfer to the amp: Direct (source to amp) is best, if you don't "bit strip" with the digital domain VC, if it does, then 10kohm passive comes in a close second, so long as the impedance are matched, which 90% of system are matched. 

But if your system is not quite right and needs to be coloured in some way, then a preamp with the "right" colouration can be fix for that, but good luck finding the "right" one. As none I know of, sound like a "straight wire with gain", they all sound different to each other.

Cheers George  

ahendler
416 posts
 
bdp24
Most of what you say is not true of transformer based passives. I had a great Sonic Euphoria passive that used autotransformers and it was great However my Shindo preamp is better
Alan
dracule1 OP
1,085 posts
 
Georgelofi, I agree Bascom's comments have to be taken with a grain of salt given he is on PS Audio promoting his design.  However, the same argument can be applied to you since you are a manufacture of LDR passive preamps.  I myself own potentiometer, stepped attenuator, LDR, and autoformer based passives believing passives are better than active preamps under the right circumstances (eg, low output impedance source, high input impedance amp, and short IC length).  But my recent experience with a modest active preamp supports much of his claims.  Time to reevaluate my prejudices against active preamps.
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