[brother love]

Jos,

Are you leaving the M451 on standby (switch "on" at back of unit) ?  Doing so drastically reduces hiss & has very minimal impact to tube life.

Are you using stock tube & is it new ?

[Jason T]

Jos

try disconnecting your sources (cd player ect)
leave only the speakers hooked up.
does it still do it?
honestly is sounds like a source is trying to ground through the sensation.
if it still does it then I would like to get it on the bench to have a look at it because then we might have a grounding issue inside the amp.
the strange part is that the amp has NO ac voltage inside of it from the psu so your touching it shouldnt have an affect.

if un hooking the sources doesnt do It I'd like you to turn off the rear power switch. turn the tube switch off, remove the tube and then turn the unit on without the tube in it.
your not boring me. I enjoy this stuff!

[Jos]

His Jason,

Disconnecting the cd/phono doesn't help.

Switching off the buffer and taking out the tube however, does: dead quiet.

Beats me.

Jos

[Jason T]

His Jason,

Disconnecting the cd/phono doesn't help.

Switching off the buffer and taking out the tube however, does: dead quiet.

Beats me.

Jos

and there you have it.

take a few pictures for me of the buffer power wires location. its the wire that travels from the buffer assembly around to the large power cap in the amp.
moving it around might just fix things. otherwise contact Gary for buffer support.
however you might want to try another tube first, thats all it takes to make a bad hiss is a bad tube

[Jos]

Hi Jason,

Tube rolling doesn't make a lot of difference. Some make it worse (old Sylvanias). one a little better (good old Philips from the days they still made decent stuff).

I must say I prefer the sound with the buffer, otherwise I'd just leave it switched off and the problem would be gone.

Here are some pictures. I bought the unit from a guy in Germany, who had bought it in Denmark. It has Mundorf caps as you can perhaps see.

Jos

[Jos]

Another one.

[Jos]

One more.

[Jason T]

I'd contact Gary Dodd on this one.
doddaudio@live.com

if he cant help you then send it back my way.

[rollo]

  Please try a new tube first [ same brand ]. Tubes can just hiss. It is not the amp IMO. My guess not the buffer design either. Maybe your speakers are very sensitive and reveal tube hiss.  Ya never know.
   BTW I think it is very generous of Jason T to offer help, cool.


charles