My amp upon turning off takes about 10 seconds to turn off (LED dims). During the final 1 second of power down there is a audiable whining, decreasing volume (obviously), increasing frequency, kind of like 'burrrrweeehp'.
Any ideas as to what may be causing this?
Cheers,
Andy
Any ideas as to what may be causing this?
Cheers,
Andy
Hi,
Bad design.
Amps as their supply bleeds off can get unstable and oscillate, or dump DC through the speaker.
A speaker delay relay can be a simple fix as not only does it add a turn-on delay, but cuts them off as soon as the power is cut.
Cheers!
Any ideas as to what may be causing this?
Bad design.
Amps as their supply bleeds off can get unstable and oscillate, or dump DC through the speaker.
A speaker delay relay can be a simple fix as not only does it add a turn-on delay, but cuts them off as soon as the power is cut.
Cheers!
Well, Geek was right (post#2) - this design is so bad that it's a small wander that it works at all.
And you got a funny case of two wrongs that make a right (and screwing everything else in the process): no Vbe multiplier bias temp. comp. but there are enormous output trans. Re (2R2) to make up for that.
If I were you I'd build any of good and proven amps from this site (symasym comes to my mind) but if you don't find it appealing, even a LM3886 would be a worthy upgrade (and you can use same heatsink and PSU).
Cheers !
And you got a funny case of two wrongs that make a right (and screwing everything else in the process): no Vbe multiplier bias temp. comp. but there are enormous output trans. Re (2R2) to make up for that.
If I were you I'd build any of good and proven amps from this site (symasym comes to my mind) but if you don't find it appealing, even a LM3886 would be a worthy upgrade (and you can use same heatsink and PSU).
Cheers !
You can start from here:
http://www.dself.dsl.pipex.com/ampins/dipa/dipa.htm
Final schematic is at the bottom of that page - Vbe multiplier is TR13 which is thermally connected to output transistors.
http://www.dself.dsl.pipex.com/ampins/dipa/dipa.htm
Final schematic is at the bottom of that page - Vbe multiplier is TR13 which is thermally connected to output transistors.
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