One month ago both are fine. Why is it only occur to 1 amp? Is there a capacitor drying? I've check the connections they all OK, have to check for cold solder. Infact now, nothing is wrong with the sound, just makes me a bit worried.
Charles, I'm not intentionally slapping my amp. Just find it out unintentionally.
Charles, I'm not intentionally slapping my amp. Just find it out unintentionally.
Charles Hansen said:Patient: "Doctor, doctor, it hurts when I raise my arm over my head!"
Doctor: "Don't raise your arm over your head."
Capacitors are often microphonic. I doubt it's anything to worry about. And stop slapping your amplifier!
Now that's funny! Maybe you heard that on the same old TV program, I heard it on. No, you couldn't be that old.
I agree that it's likely microphonics due to something physical. Modulating capacitor plates?
Bill Fitzpatrick said:
I believe you may have discovered a few cold solder joints before. I've found some, as well. Some that I caused and some the manufacturer left for me to fix. Depending on whether this amp is in a Lexus or 1 ton truck might give us a clue.
A bad solder joint would make a different sound than microphonics, don't you think? We need an MP3 sound file to listen. A cold solder joint would probably sound noisy and harsh. Maybe a microphonic sound would be more like high speed tremelo or vibrato effects.
Guy's I have to aggree with Charles, Cap's CAN go Microphonic, seen it 100's of times, in fact a guy has a Cerwin Vega A-400 here in the shop for that exact problem.
Another one is the temp compensate diode or junction (the one sitting right on the heatsink), the internal silicon "stamp" within the diode (because of heat) can become a piezo mic (well it works the same as one, when it does).
Last but not least, IF an amp is driven very hard (I'm talking comercial duty, live rock band style) the pre-drivers, or the actual outputs can also develop the same "piezo" effect themselves.
One good way to dicern the issue (WATCH IT LEATHAL VOLTAGES !!
) is to power off & unplug the power cord, remove the top cover, power the amp back up, and using an "ALL PLASTIC" rod or coil slug wand, touch the components individually ( yes you might have to "lightly wack or smack" some of them JUST remember that when dealing with them, they ARE live, and the component WON'T take as much force as the entire amp, before failing or breaking off...... (DUH !)). (Gota put some form of warning in there don't I ?? )
When the amp "Sings" you found the problem !
Who said something about "It ain't over untill the fat lady SINGS >?"
Another one is the temp compensate diode or junction (the one sitting right on the heatsink), the internal silicon "stamp" within the diode (because of heat) can become a piezo mic (well it works the same as one, when it does).
Last but not least, IF an amp is driven very hard (I'm talking comercial duty, live rock band style) the pre-drivers, or the actual outputs can also develop the same "piezo" effect themselves.
One good way to dicern the issue (WATCH IT LEATHAL VOLTAGES !!
) is to power off & unplug the power cord, remove the top cover, power the amp back up, and using an "ALL PLASTIC" rod or coil slug wand, touch the components individually ( yes you might have to "lightly wack or smack" some of them JUST remember that when dealing with them, they ARE live, and the component WON'T take as much force as the entire amp, before failing or breaking off...... (DUH !)). (Gota put some form of warning in there don't I ?? )When the amp "Sings" you found the problem !
Who said something about "It ain't over untill the fat lady SINGS >?"
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