Tube Amp Archive

Thanks for the info re pulling the tubes and yes I realise this has nothing to do with the shielding.

Yes they have the copper shielding. So it's safe to turn amp on without any power tubes?

I would go to another shop. A standard 1N4007 has a reverse recovery time of 2uS whereas a fast recovery diode like the MUR1100 has a recovery time of 0.075uS which is 100's of times faster. Tell them to read the data sheets. You can also buy a UF4007 which is an ultra fast diode.

ChopSauce: no problem.

gktamps: yes it's described as UF but not soft so not sure where Frank got that from. Anyway it's a quick mod so I will add some UF diodes to my PJ and see what it does.

His conclusions seem to be that the buzzing is greatly reduced with the new diodes, but there are other sources of noise like hissing and humming which need to be addressed in other ways. I wonder why you say the MUR1100 are slow recovery when their recovery time is so much less than the std diodes....

Yes I haven't seen the diodes as a source of buzzing mentioned anywhere else. So as long as the new diode is 1KV, 1A and around 75nS it would be ok? No other critical specs?

I have a 1994 Fender Pro Jnr amp and I recently came across a webpage where the factory rectifier diodes where replaced with quick recovery MUR1100 diodes and this greatly improved the buzzing in this amp. Its odd that the author says his PJ has 1N4007 diodes, as my 1994 PJ and every model up to 200...

How did the amp sound when you got it back together? Less noise and hum? Lots of information in your post most of which I'm still digesting.