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In Reply to: RE: Autoformers and transformers have their own sound colorations posted by Tre' on June 20, 2025 at 15:33:07
Certainly a poorly designed or implemented transformer would degrade music quality in a TVC.
The person making the comment acknowledged that they have never had a commercial quality TVC in their system. One would therefore need to assess the origin and credibility of that persons comments. I have discounted that persons entire commentary on TVCs.
Follow Ups:
Abe was not just referring to TVC/AVC. I took his statement to mean all passive preamps limit dynamics. I would like to understand just how a potentiometer has the ability to limit dynamics?
High frequencies can be lost if the output impedance of the pot is high enough to create a low pass filter too close to the audio band. The impedance that the pot presents to the source should also be considered but the requirements there are easy to satisfy. I just can't see how dynamics could be limited.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Potentiometers volume controls put resistance directly in the current path of the signal which has an associated thermal noise. The incoming signal already has a fixed SNR. By running it through that resistor you not only made the signal smaller but now mixed in the thermal noise content with the signal. Double whammy gotcha there.
You are throwing away both voltage and current in a resistive passive. You are making a relatively high output impedance as well. These all work against proper drive of the amplifier.
My experience has been that the most dynamic preamps are active (and I have had a couple different shunt passives as well as silver wired TVCs, which do better but not as good as an active) and with large and/or highly regulated power supplies with low output impedance. They then can deliver a wallop to the amp, which despite having high(ish) input impedances still want to see the big swings that an active preamp can provide.
Of course the explanation is incomplete as it follows the observation that is then seeking an explanation. Based on all the preamps I have tried over the last 25 years (a lot) my observation regarding dynamics is what I wrote above.
The three most powerful sounding preamps I have owned are the Silvaweld SWC1000, which had a fully tube regulated power supply (with 300B as the pass tube). This had silver contact and wired resistive volume controls but also transformer coupled outputs (not TVC though), the NAT Plasma, which was true dual mono with massive power supply and also fully tube rectified and regulated. This time just a blue potty VC and cap coupled output that used 6 x 7DJ8s in parallel per channel and finally the Aries Cerat Incito, which has massive unregulated (triple PI filter), tube rectified and transformer coupled output. It has a resistor network VC.
The best I have heard is the Aries Cerat top models, which have TVC but also a lot of other tech that is uncommon and perhaps beyond scope here.
current drive. It is a voltage device. ***I should have said a tube running With the grid negative with regard to the cathode is a voltage device and requires no drive current beyond driving grid resistor and the Miller capacitance*** However the Miller capacitance and cable capacitance do require current to drive them. If the output impedance of a passive preamp is too high the system will lose some of the high frequencies do to the low pass filter created by the drive impedance vs. the value of the capacitance. The -3db point of this filter is easy to calculate (or measure).I use short low capacitance wire and and input tube that has almost no Miller capacitance.
What about a DAC or CD player driving a power amp that has a level control? Do you find a reduction of dynamics in this setup?
You shouldn't. There is no mechanism for it.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 06/25/25
One solid example that I remember all too clearly was my Placette Passive linestage with relay switched discrete precision resistors in one of my systems. That setup was outstanding but I think all the components were just right and well suited for use with a passive - which is not always the case.I had the Cary CDP with its higher than typical very robust output with short interconnects driving the Passive which in turn was driving a power amp that didn't require a lot of signal for full output and that in turn was driving somewhat sensitive speakers. I was never toward to max volume limit on the Passive - more typically about midway or a little more.
That same Placette passive in another setup was dynamically dead. Which gets back to my original point that Passives (resistor or tvc) require extra measures to ensure good component matching while active preamps are less finicky and much more forgiving. I think that's pretty well known.
Why did the Passive in the 'other' setup sound dynamically dead? I don't know but it did. IMHO passives are mostly one trick ponies for ultimate transparency but they compromise in too many other areas - for me anyway.
Placette Passive Linestage + Cary CDP was outstanding
Edits: 06/20/25 06/20/25 06/20/25 06/20/25
I had the Sonic Euphoria...try as I might, it sounded poor compared to the better active preamps I had on test. You can read my review here:
https://positive-feedback.com/Issue17/soniceuphoria.htm
Look at the price point of the Aries Cerat Incito s at approximately $20K+. They better be pretty darn good at 10 to 20x the price of the Sonic Euphoria (depending on single ended or balanced).
I probably could get used to that level of performance (hopefully it is actually that good), but $20K is well out of my price point. So I certainly won't be providing my take on the Aries Cerat Incito. since I will likely never hear it.
It is nice that vendors are making really killer upscale product - perhaps that 'tech' will trickle down to lower cost products.
mentioned by morricab would be bad at any price. Wish I knew how his problems could be different from some other reviewers. However, I have read at least two reviews that mentioned the good dynamics of the Sonic Euphoria despite some loss in clarity and detail compared to some other passive preamps.
Passives are known for ultimate transparency but these one trick ponies often give up too much in other areas. I went through my passive phase with about 1/2 dozen different units but admittedly only one TVC. Passives killing dynamics was a common theme that I experienced first hand in my systems - even with the TVC. Some were better than others (Cary CDP + Placette Passive) but in all cases dynamics lagged behind good active preamps. Some were also 'thin' sounding lacking body. The McCormack TLC-1 comes to mind. The trade-offs for ultimate transparency are too great so I've been using active preamps ever since for the past decade or more.
Excerpts from the Sonic Euphoria TVC review:
[ #1 ]" ....but curiously lacking some energy. Immediacy, especially at lower volumes, was lacking and the sense of "life" that I can get from some recordings was not there. "
[ #2 ]" ...I was again struck by its exceptional transparency and subtle detail retrieval. However, these pluses were again offset by a sudden loss of dynamic energy. "
[ #3 ]" ...I believe now that a large part of the issues I have with this preamplifier stem from the sensation of the bass being disconnected from the rest of the music. Why this is occurring I can only speculate but I heard this consistently with different music selections, different sources, and different amps... "
I never experienced the weird disconnected bass with my passives. Some were 'light' in the bass but I attribute that to passives being dynamically challenged.
My point being, passives CAN sound excellent in SOME systems but component matching is critical and getting all the stars to align just so can be a challenge. Passives are unforgiving in this regard where active preamps are much more flexible... and usually more dynamic.
This is what I find interesting: I auditioned 3 different TVCs. An early Slagle, Stevens and Billington, both silver and copper wound, the silver blew the copper away, and the Silver Rock from Audio Consulting, also silver wound. All three units shared the same sound qualities, more low-level detail, better detail at low volumes (sort of the same thing) beautiful highs, better dynamics and micro dynamics and a sound stage that was better in every way. The silver wire was like 2 steps up from the copper in all these areas. From this empirical evidence, I would say that there is something going on that is very different from conventional attenuators, could it be better impedance matching? Could it be that resistive components are inherently flawed, the signal is being dissipated as heat, does this crush dynamics? No judgement please but chat GPT gave an excellent description of the subjective qualities of a TVC as well as a possible explanation stating that transforming the sound magnetically may be inherently better than resistive networks for the reasons I gave earlier. I stated this in another post but a friend also bought the silver rock with identical results in a completely different system, this is not a one off me thing. I can definitively state the a TVC in my system was the biggest upgrade that I have ever had in 40 years of playing with audio, of course you have to have other components that will allow your to hear these differences. Yes, im a fan boy!
.
Have Fun and Enjoy the Music
"Still Working the Problem"
I know Jeff and I was there when he was doing the prototypes. When he first showed me this Preamp Prototype I asked about the wiring and how large it was. Wondered how all that wiring would affect the capacitance since it was all so close to each other. I did mention if the use of smaller gauge CCC wire with Teflon insulation would work better or have any affect on sound quality. When I heard it it did sound really nice and I almost got one but at the time I had a Sonic Frontier SFL1 Signature preamp that sound really nice, so I didn't pull the trigger. On the Chassis, Jeff did all of that.
Interesting review. Thanks.
Stereophile found the PLC to be dynamic but not very transparent. Sonic Euphoria is no longer in business since that nearly 20 year old review but it looks like Placette is still around.
As for me, I prefer a good active linestage especially those with relay switched discrete stepped attenuators. I've had a few including Placette, Schiit, Benchmark, Eversolo.
Since you have never had a commercial TVC, it is hard to imagine how you could contend that you would prefer a stepped attenuator or active preamp over a TVC.This thread is about TVCs, rather than which line stages / preamps you have personally had (all NOT TVC).
Pretty funny - no thread will be spared...
Edits: 06/22/25
I'm sure some commercial TVCs can sound wonderful in certain systems but they lack features that I require. I've already mentioned those so TVC's are a no go for me."This thread is about TVCs, rather than which line stages / preamps you have personally had (all NOT TVC)."
No, the original topic of this thread is titled, " Why are TVCs not more popular . I shared input from my perspective.
If they work for you, great! They are not for me.
Edits: 06/22/25
People are always welcome to comment about something they know nothing about. Hard to say it contributes any valid content to the discussion, but to some posters that does not seem to matter.The OP asked why TVCs are not more popular. Unfounded negative commentaries, like the one weaving through this thread, are possibly one of the reasons why. Well, that does depend on whether the poster has any remaining credibility at all...
Edits: 06/22/25
I gave my input. Whether you value it or not is up to you. Others can make their own evaluations.
Sorry if you were hoping for a TVC love fest.
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