W
Watson A.Name - \"Watt Su
Guest
"Jim Thompson" <thegreatone@example.com> wrote in message
news:74m6d05622qf9arfiicgp98g831e4jm5m5@4ax.com...
transistors in the output, with a driver transformer, dual secondaries
each driving a base with opposite polarity. The primary was driven
thru a blocking capacitor, to keep DC out of the transformer for best
linearity. I think the Pilot and Acoustic Research amps used this
method. At higher power, the bias stability was of a concern, so using
a low resistance secondary winding helped a lot. Of course they had
some kind of thermal compensation such as a NTC thermistor.
Also, using a transformer prevented blown output transistors from taking
the driver(s) with them.
news:74m6d05622qf9arfiicgp98g831e4jm5m5@4ax.com...
Some of the higher power amps of that era used a pair of the sameOn Fri, 18 Jun 2004 16:23:00 -0400, "Tam/WB2TT"
t-tammaru@c0mca$t.net> wrote:
"Norm Dresner" <ndrez@att.net> wrote in message
news:mgHAc.91891$Gx4.53715@bgtnsc04-news.ops.worldnet.att.net...
"Tam/WB2TT" <t-tammaru@c0mca$t.net> wrote in message
news:7fidnbOvzoClpE7dRVn-sQ@comcast.com...
"Jan Panteltje" <pNaonStpealmtje@yahoo.com> wrote in message
news:40d312ef@post.usenet.com...
**** Post for FREE via your newsreader at post.usenet.com ****
On a sunny day (Thu, 17 Jun 2004 14:01:32 -0700) it happened
ptaylor
ptaylor@qwest.net> wrote in
5FnAc.38$UG5.76348@news.uswest.net>:
I was just digging through my box today,and found a ECG105
germanium
transistor.. (100W PNP audio output) I'm sure theres more in
that
box,somewhere..
Anybody know of any suitable schematics? ;-)
If you have only one, class A hehehehe.
They used to build complementary symmetry audio amps with a Ge
PNP and
Si
NPN.
What did they do before Si? Create a Class A headache? ;-
I have a 1969 RCA Transistor Manual. It shows some transformer
coupled audio
amplifiers. Unfortunately, the manual is too recent, because it
already has
silicon power transistors in it. Wish I had the old GE manual. That
contained vintage stuff. I seem to recall somebody did have an all
PNP push
pull direct coupled amplifier (no NPN EF); that would have been the
predecessor to the quasi complementary.
Tam
I have the 1964 "GE Transistor Manual". It shows some output stages
using both an output transformer and a driver transformer. But it
also shows some totem pole outputs using all PNPs, but with some
small-signal NPNs in the signal path.
The only old RCA manuals I have are either CMOS or tooobz ;-)
...Jim Thompson
--
transistors in the output, with a driver transformer, dual secondaries
each driving a base with opposite polarity. The primary was driven
thru a blocking capacitor, to keep DC out of the transformer for best
linearity. I think the Pilot and Acoustic Research amps used this
method. At higher power, the bias stability was of a concern, so using
a low resistance secondary winding helped a lot. Of course they had
some kind of thermal compensation such as a NTC thermistor.
Also, using a transformer prevented blown output transistors from taking
the driver(s) with them.