2. amps-preamps
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TVC vs. active pre?

I'm using a Bent Audio NOH in my system, and love the sound - it's detailed, open, dynamic, coherent, musical and very immediate.

Whenever I talk to amp designers however, the universal preference seems to be for active preamps. My feeling is that if there are no interfacing issues between the pre and the power amp (sufficient voltage drive, no impedance or capacitance problems) that an active pre can't "add quality" to the signal. As far as I can tell, an active preamp provides buffering and gain. Absent any need for these, I don't see what benefits it can provide.

Is my assessment incomplete? Are the recommendations for active preamps simply based on the avoidance of potential interfacing issues in unknown systems?

I understand that a good active may beat a poorly implemented passive, but given good design/build in both situations, what would it take for an active to beat a good passive, especially a TVC? And specifically, has anyone gone from a TVC to an active? If so, what were the system issues that prompted the change?
128x128gliderguider
blptwp
40 posts
 
I have an all tubed and vinyl only system and I have gone from active preamp to built-in passive TVC ( TX-102) in my custom made phono stage. One very noticeable differnce is increased dynamics, especially coming out from my Quad ESL 63 speakers, which is not known for it's dynamics. Also, frequency extremes do not seem suppressed. I would love to do a comparison on the same phono stage with TVC and resistor-based volume control.
marakanetz's avatar
marakanetz
5,473 posts
 
OK folks,

Have you ever gone from active pre to built-in volume control card inside of your poweramp?

If not, than THAT I consider as BEST option for any system that negates ANY impedance matching, compression or roll-offs of any kind that may or maynot occur within the transfer from active preamp unit to the power amplifier.

Technically for such "carded" power amplifier you will only need an input selector which is certainly passive or if you wish remote controlled.

The volume controll card is to be installed either between input stages or between output and driving stage. This way the older amps were made.
gliderguider's avatar
gliderguider OP
294 posts
 
I appear to have answered my own question. A new friend strongly encouraged me to try his Audion Premier line stage. Last night, four hours after I plugged it in I agreed to buy it.

In my system the Audion provided better dynamics, resolution and articulation than the NOH, and not by a narrow margin either.

It seems now that, theoretical issues aside, it still comes down to implementation.
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