headphones amp problems

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yan_b

Well-known member
Joined
Jun 8, 2004
Messages
130
Location
isr
i built this simple phone amp http://public.fotki.com/shemtov/studio/pampsch.html

it's suppose to be mobile and boost md output to 600 ohms phones.

after 30 seconds i get unsimetric distortion on the scope (draw it in the link), when i lower the input voltage it's happened again after 3-5 seconds no matter how low the input voltage is.
what could be the cause of that? :?:
 
Put one lead of your voltmeter on Ground, and measure the power-pin voltages. The should be +9V and -9V. I think you may find that there are +16V and -2V. Could be a wiring error (you don't show the input and output ground connections.
 
i actually tried that even befor i posted, all the grounds are connected to one bus that ends in the the resistors junction in the ps
i think i will change the ps , and connect the ground in the middle of the batts, and remove the resistors etc.., some how i get the feeling that something floats in the circuit.
 
ok problem solved, the ground bus was not connected to the resistors junction, but since i took measures from the junction with the voltmeter, i saw good readings, wich make me think how the hell did it worked at all?
after that i connected only one resistor to the ground bus, and got prr sujested problem and another weird wave shape :oops: , new idea for distrtion fx?
 
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