Re: Class/type of amp ?




"Arfa Daily" <arfa.daily@xxxxxxxxxxxx> wrote in message
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"Trevor Wilson" <trevor@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
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"N_Cook" <diverse@xxxxxxxxx> wrote in message
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Before wrapping up a Mackie SRM450 powered speaker I took some
representative DC voltages on the complementary pair power devices of
the
bass driver amp, for me and all else, future reference.
-42, -88, -42.8
41.2, 88, 42
What would the circuit type/ class name be, for this sort of biasing?

in comparison for horn side amp, same devices
0, -43, -.55
.55 , 43, 0

**There are only Class A, Class A/B, Class B and Class D amplifiers used
in audio. Anything else is just marketing bull***. What you have is a
Class A/B amp, with a switched rail power supply. Class H, Class G, et al
are just marketing terms.


--
Trevor Wilson
www.rageaudio.com.au


Well, you could say that about almost anything.

**Wrong. Classes of amplifiers are clearly and explicityly stated.

There are many manufacturers
that would disagree with you that it is just marketing bull***.

**Of course.

In fact I
can't remember ever seeing anywhere that a piece of regular Joe hifi has
ever been marketed as class G - or even class A/B.

**Here's where I get to say: COMPLETE bull***. Technics, Yamaha and others
have claimed Class A & Class A/B operation for their consumer (as opposed to
audiophile) grade components.

I see nothing wrong at
all with giving a derivative of an existing class, a new letter.

**Me either. Trouble is, it is POWER SUPPLY switching. The fundamental Class
of the amplifier's operation remains Class A, Class A/B or Class B in all
such cases. Rail shifting schemes are not alterations of amplifier Class of
operation.

Whilst
class G is indeed a switched rail class A/B amp, it never-the-less is
different from a fixed rail class A/B amp.

**No, it is not. The amplifier is STILL a Class A/B (or whatever) amplifier,
with a rail switching scheme attached. Of course, that does not suit
marketers, who dreamt up fancy new terms.

Based on what you're saying, you
might as well say that class D is an invalid term,

**Fair comment.

as class A and class B
and class A/B (and for that matter class C at RF as well) refer to the
point that the output devices are biased to in normal operation, whereas
class D refers to an entirely different concept of waveform reconstruction
by power device switching i.e. the fully digital output stage.

**Indeed. The term: Class D has always troubled me. It does not fit with the
accepted Class of operation of an amplifier.


--
Trevor Wilson
www.rageaudio.com.au


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