Hey guys,
My amp and speakers have been working pretty well. They are hooked up to my computer and it is verified as a good source. No noise.
The sound is hard to describe. It's hardly noticeable, but unfortunatley, after I first heard it, my ears pick it up every time. It comes out of the tweeter in one channel. It sounds almost like the tweeter is vibrating or buzzing, but it's securely locked down. I switched my speaker wires, and the same noise appears on the other speaker, so it is NOT the speaker. It is not the source either.
So it's the amp. I don't know exactly what would cause this sound. Only ideas I would have is intermittent connections? I kind of was running short on wire when I wired it all up so I had to use some cheap wire and perhaps the connections aren't good? How about a faulty potentiometer? could that make a scratchy, buzzing sound?
The buzzing sound is not constant. It goes with the music. So when the music hits, so does the buzz.
Just wondering.
Thanks.
My amp and speakers have been working pretty well. They are hooked up to my computer and it is verified as a good source. No noise.
The sound is hard to describe. It's hardly noticeable, but unfortunatley, after I first heard it, my ears pick it up every time. It comes out of the tweeter in one channel. It sounds almost like the tweeter is vibrating or buzzing, but it's securely locked down. I switched my speaker wires, and the same noise appears on the other speaker, so it is NOT the speaker. It is not the source either.
So it's the amp. I don't know exactly what would cause this sound. Only ideas I would have is intermittent connections? I kind of was running short on wire when I wired it all up so I had to use some cheap wire and perhaps the connections aren't good? How about a faulty potentiometer? could that make a scratchy, buzzing sound?
The buzzing sound is not constant. It goes with the music. So when the music hits, so does the buzz.
Just wondering.
Thanks.
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I think it's definitely not overheating. This sound is evident at very low volume levels also. I don't actually think its LM3886 related actually. I mean it could be but I doubt it.
It's not a new build. Well I mean I don't think I noticed it before. I finished building it about 4 months ago. I think something must have come loose...
Thanks.
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You did mention the computer to be a trusted source.
that's all fine.
But just for the sake of experiment, could You try the amp with a battery powered mp3 player of some sorth?
(ya, has to be battery powered.)
does this sound come when You short the inputs ?
does it come with open input?
Can You post a pick of the build, specialy I would mostly be intrested in grounding schematic and the area around the input caps.
that's all fine.
But just for the sake of experiment, could You try the amp with a battery powered mp3 player of some sorth?
(ya, has to be battery powered.)
does this sound come when You short the inputs ?
does it come with open input?
Can You post a pick of the build, specialy I would mostly be intrested in grounding schematic and the area around the input caps.
It's mostly just a kit build.
I'll do all those tests in a second. The sound as I mentioned, only comes when music is playing. It goes along with the music. So if there is a guitar playing, you'll hear the buzzing in the same rhythm as the guitar. But if nothing is playing, there is no sound.
I'll do all those tests in a second. The sound as I mentioned, only comes when music is playing. It goes along with the music. So if there is a guitar playing, you'll hear the buzzing in the same rhythm as the guitar. But if nothing is playing, there is no sound.
Ok, the other channels work fine, OK, but may be a fake cap in the circuit (For example, the power decoupling, the cap in zobel network, or some RC compensation network) that makes THIS amplifier to oscillate / become unstable, and don't affect the other(s).
Good point but all the caps are genuine. I bought all the parts myself off Mouser.
I might take a look at some of my soldering on the preamp section. Generally my soldering is good, but I remember having a sketchily soldered cap or two because they didn't quite fit right.
Here in Argentina (Buenos Aires) there was a time some years ago where some electrolytic caps exploded in the caps drawer, without use.. They were a 105 deg low ESR for motherboards or SMPS´s. The brand Jackon or something like this. Actually we are using Nichicon although costs are higher.
This is to remark that don´t be sure caps are good, measure them although appear to be good.
This is to remark that don´t be sure caps are good, measure them although appear to be good.
I'm quite aware of bad caps. But I used 100% Panasonics on this amp. I'll look around to see if anything looks suspicious though.
They're all on a single board, so I can't swap. However, I think I'm just going to use the brute force tactic. Just replace everything that I have a problem with and hope the sound goes away. Maybe I'll get new op-amps too. My op-amps were actually a little weird. I had to replace one actually because it seemed to be a dud. Maybe the other one went bad now.
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