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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
kernelbob
50 posts
 

I had also tried passive preamps, but found actives to have better bass weight and punch.  That is until I tried the Tortuga preamp.  I was surprised that the bass equaled or bettered the active preamp I owned (an ARC-REF3) with better, tighter bass, wider and deeper soundstage (with much better channel separation), and more extended & cleaner highs.  I ended up selling my REF3.

I also had a chance to compare it to another highly regarded $10k active preamp.  The Tortuga's adjustable input impedance feature (2k to 200k on the balanced one) really showed how important it is to optimize the load seen by the source.

By the way, I'm using my current Tortuga LDR1B-V2 (1 balanced input, 2 balanced outputs) to drive a biamped system with a pair of Spectron monoblocks on the bass (25 kohm) and a pair of Double Kronzilla's (with a high speed differentially balanced FET input with 100 kohm impedance).  The Tortuga is driving these just fine, still with bass power and punch and pristine mids and highs.  The balanced ICs from the Tortuga to the amps are one set of 2 meters and one set of 2.6 meters.

I'm getting a customized LDR3B-V2 with the capability to switch absolute phase on the inputs.  All this without a switch or pot in the signal path.  I'll be using my current LDR1B-V2 to attenuate the volume of the Spectrons to match the Krons.  The Spectrons need to be attenuated by around 4 to 6 dB.

dracule1 OP
1,043 posts
 
Georgelofi, I know the arguments for using passive preamps (including Nelson’s), as I am a big supporter of the passive route. Having used passives of all types for the past 9 years, I know the benefits. It’s just that this little modded active preamp has turned my views upside down. The only thing I don’t like about this active preamp is the over damped bass which doesn’t sound quite natural. Everything else is as good or better than my LDR preamp and other passives in my arsenal.
dracule1 OP
1,043 posts
 
Kernelbob, I too have the Tortuga Audio preamp with variable impedance. It is the best passive I have ever tried. However, my modded active preamp, which I bought used (no longer in production) and had it modded (under $500 total for preamp and mod), is better or just as good in almost every category, except for the bass which I have indicate earlier is too damped. The Tortuga has the best bass of any other passives I’ve tried. Its bass is like that of a very good active preamp, extended and dynamic with just the right amount of natural bloom.
david12
1,398 posts
 

The first thing I would say, is how different Passive's can sound from each other. I had a chance to compare 4 Passive Pre's over a weekend, which might not have been long enough, but two were frankly poor, muddy, lacking  detail, dynamics and base. I had a DIY built clone of the Music First Audio Baby reference and an actual Baby reference. Both were excellent in comparison. In fact, what one is led to expect from a Passive, quite neutral, transparent, with no hint of colouration to my ears. The actual baby reference was a little better.

 On the basis of this test, I believe the MFA Baby reference is hard to beat compared with many active Pre's. Like Kernelbob, I think it clearly bettered the ARC Ref 3.

 What am I using now, the Modwright 36.5? I just prefer it to a Passive, greater dynamics and a more engaging, enjoyable, musical, for want of a better word, sound. Still if you get a chance of auditioning an MFA Baby Reference in your system, give it a try. Before anyone else says it, I agree, it is quite expensive, so try and find a second hand one.

milpai's avatar
milpai
1,341 posts
 
I am saying this specifically for TVC. I have said this many times and will repeat again. You need to make sure that a TVC should have a MATCHING system. You really need to look into the source voltage, amplifier sensitivity, loudspeaker sensitivity, cables, etc for your system to "come alive" with the TVC. If you have taken good care, then it is really difficult to beat a well made TVC. Years back I heard that the "core" of the TVC also made a difference. From my personal experience I have compared my $1.6K TVC to a $4K active preamp and the preamp went back to the dealer. I have plenty gain in my system and absolutely have no issues with bass or treble. At this point, my speakers go down to only 40Hz. I am looking forward to upgrade to a loudspeaker that goes down to at least 30Hz. I am sure that my TVC can easily handle that.
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