"N_Cook" wrote in message
...
Arfa Daily wrote in message
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"N_Cook" 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

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/




Class "G" maybe, where the supply on the output devices doubles 'on the
fly'
depending on current demand (as in amperes)? Lots of amplifiers are now.
The
supplies are often designated "VH" and "VL". First units I ever came
across
which used it, were an Aiwa series of hifis, which did the supply
switching
with a pair of FETs. I think this covers the principles


http://www.wipo.int/pctdb/en/wo.jsp?...546&DISPLAY=DE
SC

Arfa




I don't have the schematic or even saw the track-side of the Mackie board
but that explains the presence of power FETs

Do you know if the pdf of that OCR'd doc (so no schema) is publicly
available, I could not find it explicitly on that page.




Don't know, to be honest. I just Googled "class G amplifier" to see if I
could find you anything on the principles, and that document seemed to cover
it pretty well. I'm sure that there must be something else out there with
diagrams. If not, let me know, and I'll scan one of the Aiwa schematics for
you. They were reasonably straightforward, as I recall.

Arfa