[Dave xxxx]

Strange getting hum from the right channel of a valve amplifier before it's
switched on !!!!!!!!!!!!!!!!

With speakers and tuner all plugged in but mains switched off a hum
????????/

Red Rose 5

instructions here

http://www.redrosemusic.com/literature/model_five.pdf

Anyone any ideas ?



ta in advance and merry Christmas


regards


Dave

[tubegarden]

Dave xxxx wrote:
Strange getting hum from the right channel of a valve amplifier before it's
switched on !!!!!!!!!!!!!!!!

With speakers and tuner all plugged in but mains switched off a hum
????????/

Red Rose 5

instructions here

http://www.redrosemusic.com/literature/model_five.pdf

Anyone any ideas ?



ta in advance and merry Christmas


regards


Dave


Hi RATs!

NEVER again shut it off!

Merry Xmas!

Happy Ears!
Al

[Phil Allison]

"Dave xxxx

Strange getting hum from the right channel of a valve amplifier before
it's switched on !!!!!!!!!!!!!!!!

With speakers and tuner all plugged in but mains switched off a hum
????????/

Red Rose 5

instructions here

http://www.redrosemusic.com/literature/model_five.pdf

Anyone any ideas ?


** Magnetic induction into the right channel's OT from another unit with
its AC transformer close to the RR.




......... Phil

[boardjunkie]

Phil Allison wrote:
"Dave xxxx

Strange getting hum from the right channel of a valve amplifier before
it's switched on !!!!!!!!!!!!!!!!

With speakers and tuner all plugged in but mains switched off a hum
????????/

Red Rose 5

instructions here

http://www.redrosemusic.com/literature/model_five.pdf

Anyone any ideas ?


** Magnetic induction into the right channel's OT from another unit with
its AC transformer close to the RR.


Yep...that'd be my take on it. I repair pro sound gear and I've had a
few guitar amps make a faint strange sounding hum through the spkr out
with the unit in stby due to an output transformer being laid out too
close to the pwr transformer. Steel chassis material tends to
magnetically couple transformers in close proximity.

[Phil Allison]

"boardjunkie"
Phil Allison wrote:
"Dave xxxx

Strange getting hum from the right channel of a valve amplifier before
it's switched on !!!!!!!!!!!!!!!!

With speakers and tuner all plugged in but mains switched off a hum
????????/

Red Rose 5

instructions here

http://www.redrosemusic.com/literature/model_five.pdf

Anyone any ideas ?


** Magnetic induction into the right channel's OT from another unit with
its AC transformer close to the RR.


Yep...that'd be my take on it. I repair pro sound gear and I've had a
few guitar amps make a faint strange sounding hum through the spkr out
with the unit in stby due to an output transformer being laid out too
close to the pwr transformer. Steel chassis material tends to
magnetically couple transformers in close proximity.


** That is why you see PTs and OTs with cores aligned at right angles when
they are sited adjacent - as in all the older Marshalls.

Later Marshalls, with the transformer lams parallel with and pressed against
the chassis, are sited at opposite ends.



........ Phil