Hi all tubelovers 🙂
A friend of mine got his hands on this little amp.
The problem is, that after a (very) few minutes, it starts to hum. Quite loud in fact. Changed all the electrolytic caps, they looked kinda done 🙂
The hum is still there and I noticed that one of the tube lights more than the others. I believe it's a push-pull amp, so there should be some balance in it.
My quess is, that the tube needs to be changed, but since i'm not into tube ( not saying i don't like them 🙂 ) i thought i'd ask in here 🙂
/Henrik
A friend of mine got his hands on this little amp.
The problem is, that after a (very) few minutes, it starts to hum. Quite loud in fact. Changed all the electrolytic caps, they looked kinda done 🙂
The hum is still there and I noticed that one of the tube lights more than the others. I believe it's a push-pull amp, so there should be some balance in it.
My quess is, that the tube needs to be changed, but since i'm not into tube ( not saying i don't like them 🙂 ) i thought i'd ask in here 🙂
/Henrik
Attachments
Output valves
John,
Sorry, forgot all about the valves. Your hawkeye tell you right.
ECL86 it is 🙂
I have the schematic at work. Will post it tomorrow
/Henrik
John,
Sorry, forgot all about the valves. Your hawkeye tell you right.
ECL86 it is 🙂
I have the schematic at work. Will post it tomorrow
/Henrik
Hawkeye? Well...
Henrik,
It's not such a feat. The ECL86 is the only audio specific triode-pentode that has a half-height triode section. This is clearly visible on your image.
Regarding the hum, is it on one or both channels?
It should be possible to run a channel (with severely reduced performance) with one output valve, for test purposes.
Cheers,
Henrik,
It's not such a feat. The ECL86 is the only audio specific triode-pentode that has a half-height triode section. This is clearly visible on your image.
Regarding the hum, is it on one or both channels?
It should be possible to run a channel (with severely reduced performance) with one output valve, for test purposes.
Cheers,
Those transformers looks familiar to me.
They look identical to the ones used in the Edison 12 amp.
Made by Partridge, I believe.
I have a couple of those OPT:s and I´m putting them to use in a 6AQ5/EL90 amp.
They look identical to the ones used in the Edison 12 amp.
Made by Partridge, I believe.
I have a couple of those OPT:s and I´m putting them to use in a 6AQ5/EL90 amp.
John,
I will try and find out regarding the hum tomorrow.
Will try and see what happens when removing one of the tubes as well. Do you have any idea what it will sound like?
/Henrik
I will try and find out regarding the hum tomorrow.
Will try and see what happens when removing one of the tubes as well. Do you have any idea what it will sound like?
/Henrik
Henrik,
Removing one output valve will:
Reduce the gain a little
Cause loss of LF, especially at higher power
Increase distortion
But!... and I hadn't thought of this...
Removing one ECL86 will also remove the triode section which may not be "channelised", so perhaps the sound might dissappear!
Cheers,
Removing one output valve will:
Reduce the gain a little
Cause loss of LF, especially at higher power
Increase distortion
But!... and I hadn't thought of this...
Removing one ECL86 will also remove the triode section which may not be "channelised", so perhaps the sound might dissappear!
Cheers,
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