amp noise
Hello, i have been unable to reply the last few days but here I am,
I apreciate your suggestions and will check the cap and windings and see what happens when the inputs are shorted. ??
the humm isnt affected by the volume pot, it is always there and the audio is fine when i turn it up but the buzzz is still there behind it. ( you can here it when there is no other sound).
thanks. dw
Hello, i have been unable to reply the last few days but here I am,
I apreciate your suggestions and will check the cap and windings and see what happens when the inputs are shorted. ??
the humm isnt affected by the volume pot, it is always there and the audio is fine when i turn it up but the buzzz is still there behind it. ( you can here it when there is no other sound).
thanks. dw
Takes ze lid off and carefully peruse the internals. Locate rectifier system and see if made of discrete diodes, check components for discolouring from overheating.. They could be on their way out leading to a catas'ic failure. As per previous suggestions..A buzzing transformer will always change it's pitch when put under pressure..If you say "all channels" then seems more a electrial problem. Dodgy fuses, input sock and so on. Did you spill beer on it ?
rich
rich
EMI problems are more nasty.......if you don't have a oscilloscope then a portable radio tuned on LW or on lowest MW band will pick up interference near the equipment. A poorman's detector.
This will be in the form of birdy noises, cat whistles and will be obvious hash. If this happens then you have a nasty problem. Put loudpeaker leads near radio and see any difference in radio backgound noise.
If you do hear obvious problems then somewhere in the output stages lies the snags (or dodgy rect diodes I ment'd prev). Or circuit has duff IC. As transistor amps have a response that goes in the RF spectrum, then you have to seriously look at board earthing (screws etc)and condition of all cables, cap bypass etc. In saying this, the radio pick up is very good at picking up instability, bit if your amp has already a SMPS in it then this technigue anin't going to work.
In general, EMI will be present when unit is electrically unstable,
transformer buzzing is mechanical. I suggest disconnect your good speakers and use others while you do these tests, as I there is a serious DC drift due to problems, then you won't regret the loss.
That's about as far we can take it.
My other suggestion is more drastic, ditch the dammned SS amp and find a tube amp which is more reliablei n long term.
VIVA..... tube amps!
rich
This will be in the form of birdy noises, cat whistles and will be obvious hash. If this happens then you have a nasty problem. Put loudpeaker leads near radio and see any difference in radio backgound noise.
If you do hear obvious problems then somewhere in the output stages lies the snags (or dodgy rect diodes I ment'd prev). Or circuit has duff IC. As transistor amps have a response that goes in the RF spectrum, then you have to seriously look at board earthing (screws etc)and condition of all cables, cap bypass etc. In saying this, the radio pick up is very good at picking up instability, bit if your amp has already a SMPS in it then this technigue anin't going to work.
In general, EMI will be present when unit is electrically unstable,
transformer buzzing is mechanical. I suggest disconnect your good speakers and use others while you do these tests, as I there is a serious DC drift due to problems, then you won't regret the loss.
That's about as far we can take it.
My other suggestion is more drastic, ditch the dammned SS amp and find a tube amp which is more reliablei n long term.
VIVA..... tube amps!
rich
ViVa tube amp.... bah!
Anyway I was under the impression that this was a home brew amp, not any longer. Anyway I had a similar problem of buzzing in my amp and this was resolver by relocating the earth wire away from the traffo, it was picking up buzz and the amp buzzed because of it!. Anway I doubt the problem is the same, as im assuming that the amp has, at one time, not buzzed. If this is the case then try the caps. If tho some of the internal wiring is hard wired, not PCB stuff, if an earth wire has moved it could be picking up stray buzz fields .
Anyway I was under the impression that this was a home brew amp, not any longer
. Anyway I had a similar problem of buzzing in my amp and this was resolver by relocating the earth wire away from the traffo, it was picking up buzz and the amp buzzed because of it!. Anway I doubt the problem is the same, as im assuming that the amp has, at one time, not buzzed. If this is the case then try the caps. If tho some of the internal wiring is hard wired, not PCB stuff, if an earth wire has moved it could be picking up stray buzz fields .- Status
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