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[email protected] dpierce.cartchunk.org@gmail.com is offline
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Default I just am not satisfied

On Tuesday, November 20, 2018 at 6:01:26 AM UTC-5, Trevor Wilson wrote:
On 5/09/2018 9:09 pm, wrote:
I just am not satisfied with the sound from any solid state amplifiers.
I have tried high end home amps and even some top of the line amps made
for commercial use. (Stage equipment).


**Then you need to listen to some different (SS) amps.


I suspect that if its stage equipment, the amps AND the speakers
are of the same class, where audio fidelity is NOT a primary
design driver.

I miss my old tube system that I had years ago. Those tube amps pumped
out 300W (RMS) and had more actual power than my current 1200W (RMS)
solid state system..


You actually measured this? Really?

I'd be curious to know which valve amps you had that
could deliver 300 Watts (continuous). 1,200 Watts,
continuous, is impossible, unless you are operating on a
multi-phase power supply.


Not necessarily. let's look at the details.

Let's assume an optimally designed and biased class AB tube
amplifier. The output stage is going to run at 40% efficiency,
tops, which means at 300 watts, it's going to be pulling
300 watts/40% or 750 watts from the wall. Generously assume
the power budget for the remainder of the amp is 40 watts
(filaments, dancing purple glow, etc.), means that the power
supply has to provide about 800 watts. Assume the power supply
transformer is running at about 90% efficiency, that means the
amp, running full tilt, is consuming around 900 watts. It will
run fine by itself on a single 15-amp circuit, at worst pulling
7.5 amps at 120 VAC.

Now, let's do the same for this hypothetical 1200 watt amp:
assume the same 40% class-AB efficiency, but we need much less
of a power budget for everything else, so consumption from the
supply is 3000 Watts. Assume the same transformer efficiency,
that's 3400 watts. At 120 volts, that's 28 amps at 120 VAC,
a lot to be sure, but it would run fine on a 30 amp. Run it at
240 VAC, that's 14 amps.

Look at it another way, it's like running a 1.25 HP vs a 4 HP motor
under load: at 220 VAC, you don't need multi-phase power (well,
multi-phase would help startup, but that's not so much of an
issue with an amplifier).

I like the warm sound of the metal elements and the heat of the filament
inside of tubes.


**Nope. More likely, you are focusing on other aspects of the
amplifiers. Things like:

* The lack of extension at both ends of the frequency spectrum.


Except in some pathological cases, the real difference in bandwidth
is insignificant.

* The excessive levels of even order harmonic distortion.


Sorry, this is something of a myth. A lot of tube crcuits do
have even order harmonics, not because they're tubes, but
because they are essentially running single-ended (not meaning to
suggest they are one of those pathological examples of single-
ended power amps using ancient fire bottles like 300Bs).

A similar single-ended solid state circuit with bit of non-linearity
will also have an emphasis on even-order products.

But, if the guy's listening to the kind of amps he claims, we
can rest assured these are push-pull, symmetrical amps, which
means regardless of whether they are solid state or tubes, the
non-linearities will be symmetrical and thus the distortion
products resulting from the non-linearities will be be predominantly
odd-order.

* The lack of hard Voltage limiting.


Only an issue if they guy is listening at such levels the amps
are spending a lot of time clipping: and in such cases, the speakers
almost inevitable have order of magnitude worse distortion.

* The lack of current limiting problems.


Well, no: if the amps have the power levels he claims, betcha they
have plenty of current. And

* The excessively high output impedance, which leads to frequency
response errors that please you.



Maybe.

All of which can easily be duplicated with transistors, should a
designer desire it.


Yes, a designer can. Remember a corralary of Suffolk Audio's
first law of acoustics:

Any idiot can design an amplifier and, unfortunately,
many do.

Plus I miss watching the dancing purple glow (purple
haze) inside of the tubes. (You don't see anything in
solid state amps).


Depends upon what you're smoking, and whether that smoke is
coming from the amps with the tubes that are seriously over-driven
and not just a little gassy, or somewhere else.