Is my preamp useless?

"03-27-15: Milpai
Zd542, don't feel offended just because you have not listed your system here.

But I found this statement funny :-)

Most of the stuff I recommend, I don't even own. "

No one likes a good laugh better than me. No offence at all. Just the opposite actually.

"Are you telling me that you are recommending stuff on a whim? We were not talking of putting together a system for the OP."

No. Not everyone has the same taste as I do. Sometimes what an OP will ask for is clearly not to my personal taste. It would be selfish of me to recommend only things I like, knowing full well that its not the best advice. For example, I don't like Magnepan and B&W speakers, but I would never think of talking someone out of them if that's what will make them happy.

I think you were generalizing that Actives were better than passives. I do not think I attacked your statement in any way. I was suggesting that we cannot make generalized statements. Isn't TVC a passive component?

No worries- but apparently what you were thinking is not exactly what I was saying since I was careful to not generalize. If you review my posts you will see that I make a point of also saying that not all active line sections are created equal. The phrase I like to use goes like this: 'It is a statement of how poor many line stages are that passive volume controls can beat them'. So I am always careful to use the phrase 'properly designed'.

So far this thread has really been about active preamps vs PVCs (Passive Volume Controls).

TVCs (Transformer Volume Controls) should not be considered in the same realm as PVCs. The math regarding how they function is quite different.

TVCs involve a transformer or autoformer with taps. They have a different set of issues- for example if improperly loaded the device will not express the turns ratio correctly and so bandwidth will not be flat (inter-winding capacitance can start playing a role). This means that the designer has to provide the proper loading for each step in the setup, taking into account that the amplifier (which might have an input impedance anywhere from 10K to 100K or more) is part of that load.

A lot of TVC designers don't take all that into account. So some of them are easily beaten by active line stages because the active unit is more tonally neutral). OTOH, there are TVCs that have all the design parameters sorted out and they can have impressive performance if used correctly.

If a TVC provides gain (and sometimes even if it does not) and depending on the type of amplifier used, the interconnect cable may well play a serious role in the results! Cables have capacitance and TVCs are all about inductance- the two together can result in a high frequency resonance that varies with the control setting.

If you can hear big differences between interconnect cables, what you can safely conclude is that the 'good' cable you have now and the one that didn't make it are both wrong. The why of it is simple- did you audition all the cables out there? Will the manufacturer of the cable you settled for make a better one next year?

A properly designed active preamp eliminates this issue- the cable plays a far less of a role in the tonality and resolution of the system. A good active will force the cable to do its job- to pass the signal without editorial. I don't see PVCs or TVCs really doing that.

I agree that I have not auditioned all the cables that are available. Will the manufacturer make a better cable next year - chances are most likely yes. Isn't advancement in technology supposed to do that? Nordost, Siltech, Shunyata, etc, all come up with new improved cables over a period of some years. Folks have done A-B comparison with the new-old and preferred one of the other. Does it mean that these cables are wrong?
There are tons of users on this forum who use very highly regarded active preamps (probably 3X-10X the cost of my entire system), and have experienced a better sound when their cables were upgraded. Does it mean that all these highly regarded active preamps also have not been designed properly? So which one would you say is wrong: cables or active preamp?

Scare tactics of the capacitance of interconnects with passive preamps are off the mark. As most good interconnect cables are less than <100pf (picofarad) per foot. And at 1-2mts are fine.

Only when you get into cheap nasty cables do these scare tactics come into play, when they have >200pf per foot or higher, and those types of cables have no right in hi-end audio.

Cheers George

Just to add to the above, when these high capacitance interconnects (>200pf per foot) are used, they can cause a high frequency filter, not only with passives but also with the many tube preamps.
This is another reason they have no place in hi-end audio. Thank god there are not too many of them around.

Cheers George