Amp for Apogee Stage's

Cjfrbw,

Unless you do the measurements, you can't know what's going
on.

I've put current limited tubes amps on the Stages - have seen
the tube amps strain, and fail to deliver the current needed
to compensate for the depressed impedance, and had audiophile
friends gush over how "liquid" and "lush" the sound was.

Then you put on the hefty high current amps - and they do put
out the current to keep the Stages accurate - and the
attending audiophiles complain about "glare" and being
"etched".

I think some audiophiles just plain LIKE some of the natural
rolloffs that tubes provide.

Even the simplest single-tube amp is not perfectly linear;
the output characteristics of a tube are not perfectly
linear - they do "roll-off" at higher signal levels.
[That's why you hear that tubes clip more "softly" than
solid state - they are NOT linear up to the clipping point.]

It doesn't take a complex amp to have these non-linear
characteristics - the basic characteristics of the tubes
have these non-linearities.

If you like that sound, fine - go with what you like.

Just don't fool yourself that your system is accurate.

Dr. Gregory Greenman
Physicist

Morbius, what are you using to drive your Minigrands?

There wouldn't be amplifiers at all if it weren't for rigorous scientific types making observations about materials and circuits. They certainly make a greater contribution than the mincing aesthetes.
However, there is a point where the mono maniacal pursuit of concepts such as "accuracy" merely become alternate superstitions. I wouldn't claim any stereo system is "accurate", whether tubed or solid state, whether the input and ouput waveforms looked like each other or not. "Accuracy" is such a limiting concept when applied to audio.
However, when a tubed amplifier allows me to distinctly hear and follow four voices in a vocal harmony with ease and a solid state amplifier makes it sound like one voice, I know which one I want to listen to.
The point is that Apogees do not absolutely require the high current amp refrain that has been passed around for years. There are alternatives and everybody needs to let their own ears be their guides, as usual.

Muralman1,

I drive my Apogee MiniGrands with a Class A,
Full-Power-Balanced, "cx"-series stereo Krell.

Dr. Gregory Greenman
Physicist

Cjfrbw,

I agree with your last comment that one has to let one's
ears be the final guide.

All I'm saying, is that many tube amps when confronted with
the complex impedance dips of the Apogee ribbons will not
have the current reserves to drive enough current through
the ribbon so that the voltage is what it is supposed to be.

Once the amp can't put the required voltage on the speakers
input terminals - then all bets are off with respect to
accuracy.

Accuracy isn't a limiting concept. The music signal being
sent to the speakers is encoded as a voltage. If the amp
can't put the correct, and I do mean correct; voltage on
the speaker's terminals - then you are doing something
inaccurate to the music.

Now you may like what you hear - but if your amp is not
putting the proper voltage on the speaker's terminals -
then all the great qualities that you are ascribing to the
music - are not qualities of the music - because the
musical signal isn't being accurately represented to the
speaker. Once that inaccuracy creeps in - there's nothing
the speaker can do to correct it.

However, you may like what the speaker puts out - you just
have to accept that it, of necessity; it is something
different than what the musician intended; regardless of
how much you may like it.

Dr. Gregory Greenman
Physicist