George, the "passive" "active" debate seems to me more problematic the the tube versus SS debate, for in the latter, there remains room for both to coexist. The passive argument, if right, threatens manufacturers of active preamps, reviewers and magazines supported by advertising from makers of active preamps, and also threatens owners of active preamps that have invested in them and might feel compelled to justify the expense of the gear and protect it from dimishment of the value of their asset. Not to say that there are not systems that need an active to perform well, and I think that is covered here pretty well.
In a review of the Wytech Opal in Positive Feedback, the reviwer said:
Something very interesting goes on when a preamp handles a low-level signal (or not so low in the case of CD). In theory, a preamp should be unnecessary when the source is capable of 2 volts (standard maximum output for a CD player), but experience has shown me that doing without an active preamp does not lead to improved sound. One possible explanation for this is that most CD players have relatively weak output stages. In most cases, they consist of a few op amps and/or some discrete transistors, driven by a power supply that can barely be deemed adequate by high-end audio standards. For the purpose of driving an amp, most are inadequate, and the result is often a bit harsh and/or harmonically "bleached." There is resolution but not refinement, suggesting a system under stress at musical peaks. Also, the sound often lacks dynamics. Many internet contributors claim that this is the sound that was actually recorded, and that if you don't like an aggressive, flat soundstage and lifeless dynamics, you simply can't handle the truth. Some even conclude that an active preamp, which can provide effortless dynamics, a deep, wide soundstage, and palpable, 3-D imaging, is in fact generating artifacts or "enhancements" that are not on the recording. I don't believe that these effects are artifacts, but information that is lost when those recordings are played on lesser systems. Making classical recordings in a real space has led me to believe that these spacial characteristics are real, and can be either captured or added in the mix.
Another argument for eliminating an active line stage is it does not in fact amplify anything, but acts "merely" as an attenuator 90 percent of the time. While it is true that the input is often of a higher voltage than the output, an active preamp also gives the signal a deep reservoir of current drive and voltage stability from its own power supply. Think for a moment about how a preamp works. First, the signal from the source arrives and is attenuated, then the signal is amplified again—replicated, if you will—by a circuit that has a larger and more stable power reserve than the original source. Since the gain of most preamps is fixed, the active part of the line stage is always amplifying the signal, not attenuating it. Since it is only the amount of signal to be amplified from the volume attenuator that changes, the concept that an active line stage is only attenuating the signal is false. In fact, the preamp first reduces the incoming signal, then beefs it back up with (ideally) the same amount of information, but greater drive and control."
What do you think of that? I think my EMM Labs must have a pretty good power supply....
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