Are passive preamps better?

If I can speaker to some issues not previously addressed:

There are four functions a line stage has. They are:

1) supply any missing gain
2) provide volume control and input selection
3) provide buffering of the volume control from external impedances
4) (and least understood) control the interconnect cable.

Passive systems provide only #2. Most line stages provide 1-3. If that is all they can do, it will be likely that there will be tradeoffs with a passive, perhaps in the passive's favor. If, OTOH, the preamp is capable of all four functions, then it is likely that the active linestage will be superior.

This is because the interconnect cable plays a serious role in the system. As any passive owner can tell you, the passive sounds better turned up rather than turned down. This is because the passive cannot control the interconnect. At the extreme opposite, a preamp that *does* control the interconnect will be found to be immune to the type of cable and its length.

The unfortunate thing is that you can count the number of such preamps in the high end audio community on your hands with fingers left over, because most preamp designers do not acknowledge the 4th function.

Of course, different line stages exhibit different levels of competence. This definitely muddies the waters somewhat!

This is a good part of why there is a divergence of opinion. There would be none if everyone could hear a competent linestage that can control the interconnect cable, but even that is not likely so this debate will continue.

Tbg, thus my final comment on my post!

Several decades back, this problem was addressed by the recording/broadcast industry, for pretty much the same reasons that audiophiles deal with today. The result was the balanced line system, which is actually a standard.

The standard requires that the source (preamp) be able to drive a 600 ohm load. There are several practical reasons for this, not the least of which is that the low output impedance of the source thus has the ability to 'swamp out' the effects of the cable caused by capacitance and other construction issues. The result was twofold: not only can a preamp that supports the 600 ohm balanced line standard control the interconnect so well that essentially the quality of the cable has little bearing on the sound, but also the length of the cable became all but irrelevant as well.

The number of preamps in the high end audio world that support the 600 ohm standard without any sonic artifact (loss of bass and/or dynamics) are very few. Some use output transformers, and that is why the termination standard is 600 ohms, so that the transformer can drive a reasonable load without ringing. If there is no transformer, then the termination is less important.

If you have ever wondered why 'audio engineers' say that the interconnect cables make no difference in the sound, this is why: in their world it is true because they use low impedance balanced lines. Audiophiles can take advantage of this though, as low impedance balanced lines offer the same advantages to them- the standard was in fact created to solve the sonic artifact issues that audiophiles routinely experience.

Eldartford, 600 ohms may be tough, but not impossible. We developed a direct-coupled output, not unlike our power amps, to do the job. I think our MP-1 might one of the few preamps that can drive headphones directly as a result.

Tbg, I've had direct experience with the older Cello stuff. It doesn't seem that it was designed with 600 ohms in mind.

We have a cable industry in high end audio based on the experience of audiophiles hearing differences in the cables.

However most audiophiles don't get that the recording/broadcast industry tackled this problem in the late 1940s and early 1950s, the result being the balanced line system.

For decades, audiophiles listened to inexpensive single-ended gear at home. Single-ended cables do not have a termination standard, so to get around the differences in cables that thus resulted, the cable industry began to develop, starting in the late 1970s, lead by Robert Fulton.

But the balanced line system has the advantage of making an inexpensive balanced cable sound as good or better than the best single ended cable (price no object). The first balanced line audio product was introduced to the high end audio world in 1989, possible because of the increased budget allowed in high end audio, but balanced line has had an uphill battle due to audiophiles not really getting why balanced line is an advantage. I hope my explanation here helps; balanced line exists specifically to eliminate cable problems!

BTW the classic passive volume control problem is lack of bass impact at low volumes. Some controls are built to be very low impedance to try to get around this problem, but that low impedance limits the number of front end products that can work with them.