2a3 valve strange behaviour?

[Arkless Electronics]

This may interest you: http://theartofsound.net/forum/showt...214#post698214

[the_doc735]

Probably dodgy valves, simple as that. I've seen this loads of times..... Unfortunately there are valves out there that simply aren't fit for purpose. It's not as bad as it once was.... but still not as rare as one would like!

A recent example, which I actually expected from knowing how dodgy the brand of valve was, is in my own Leak Stereo 20. I was made an offer I couldn't refuse for the Mullard GZ34 and had three Edicron ones brand new in their boxes. Each lasted about 2 days before a bright flash and the HT fuse blowing. Like I said, from experience I was pretty much expecting this to happen. I'll eventually get round to fitting SS rectifiers and that will be that sorted

I hope it hasn't damaged your OPT! Ideally fuse should have gone first of course...

Arh yes! I had heard that there are some valves not fit for their purpose. On forums there seems to be 'for and against' arguments in reliability. Yes I hope I haven't damaged the OPT too? Well tonight after 24 hours cool down, I put the original valves back in and so far they have worked perfectly. The centre tranny there is a slight vibration but it might have been like that all the time anyway AND slight buzz/hum from the left speaker but again it might have been like that all the time anyway? You can only hear it with your ear jammed right up against the speaker with the volume max'd out! The left channel is were the dodgy valves where! The 2 small tranny's run about 30 degrees 'C' and the centre one runs about 34 degrees 'C', however, there are loads of heatwaves from the rectifiers 'hitting' the centre tranny and warming up the casing of the tranny.

[the_doc735]

This may interest you: http://theartofsound.net/forum/showt...214#post698214

this sounds familiar:

8/ “An output valve has failed in my amp but it still seems to work. Can I continue to use it?”
An amp can sometimes still work with one dud output valve, especially if it has four output valves,(they function as two push-pull pairs) but this will only happen in those cases where the valve fails harmlessly (open circuit) and behaves as if it just isn't plugged into its socket. There will be less power and more distortion under these conditions. It will not be good for the remaining valve on that side that's trying to do all the work though....

Mine seemed to have less power, more distortion, and then ~ the other one on that side also went bright (i.e. trying to do all the work?) !!

[pure sound]

This issue only occurred when the Sovtek 2A3's were replaced with some Chinese made items. Putting the Russian valves back in has resulted in no further misbehaviour.

Personally I avoid Chinese power valves if at all possible. I've recommended that the supplier of these valves is asked for a refund.

[the_doc735]

This issue only occurred when the Sovtek 2A3's were replaced with some Chinese made items. Putting the Russian valves back in has resulted in no further misbehaviour.

Personally I avoid Chinese power valves if at all possible. I've recommended that the supplier of these valves is asked for a refund.

Well, they have said that I can have a refund but without any of the EXPENSIVE postage costs to/from Hong Kong. However, ebay says:

"Here's what we found for "Who pays for return postage costs?"

Sellers pay for return postage if there's a problem with the item. For example, if the item doesn't match the listing description, is damaged or defective or is counterfeit."