On 3/17/23 15:26, Iain Jamieson via Jukebox-list wrote:
I have an AMI R2777B Basic Amp plus the R2728A power amp.
Screened on top of the chassis is 6973 for the output tubes. However, they are not 6973
They are a larger 8 pin socket which looks to be factory installed.
Take pictures of the top and bottom and post to imgur.com
. Send a link
to the list. It's possible they're configured for octal tubes from the
factory or it was converted if 6973s were unavailable. Could be 6L6,
more likely 6V6 or 7591. Heater current for 6L6 is double that of 6973
and could overload the transformer.
Did these amps ever come out with say 6L6 tubes? The
wiring on the sockets suggest it may be these as pin 1 and 6 are not connected, but I
couldn't find any info to support this.
On the original 6L6 (and most octal metal can tubes), pin 1 is connected
to the metal case and used as a shield. This was typically tied to
chassis ground. Glass 6L6 tubes have pin 1 unconnected and it is often
used as a tie point.
I noticed that you're in NZ. AMI jukes or parts for them outside of the
US were often partially sourced locally, sometimes under the BAL-AMI
label. In that case it's possible that your amplifier is substantially
different from the USA version.
Jay Hennigan - jay(a)west.net
Network Engineering - CCIE #7880
503 897-8550 - WB6RDV