I am building a 12v split rail power supply with center tap transformer to power an OPA2604 in a buffer i built for the output stage of a tuner. When the power supply is attached to the pin 4 and 8 of opamp, the positive rail gets dragged down to +3v and the B+ rail jumps to -22V. I am curious to learn why this is occurring. In this scenario, the sound coming out the buffer is sorta as expected but there is a degree of distortion introduced. I checked my work and I did not find any wiring faults. When the power supply is not attached to any load both rails are +-/12.02v. The grounds of both circuits are isolated from each other, just as in the working version of another tuner I have. During my trials I tied grounds of the tuner and power supply together and received a sawtooth-like waveform on the positive rail while it dipped to 9-10VDC, seen on the scope, and a loud buzzing sound in the output of buffer, both channels. I am also curious to learn why this is. Could a coupling cap solve this?
I have done the same mod on other tuners with the same circuits without problems and amazing increase in SQ.
The power supply I am debugging.
Another working split power supply for the OPA2604 buffer, shown as example.
Power supply connected to buffer. Green = B+
The circuits I am working with.
I have done the same mod on other tuners with the same circuits without problems and amazing increase in SQ.
The power supply I am debugging.
Another working split power supply for the OPA2604 buffer, shown as example.
Power supply connected to buffer. Green = B+
The circuits I am working with.
Check the continuity of all of the grounds, I suspect you'll find a problem there. And cover that red primary lead of the transformer, it's live.
Mike
Mike
If you mean should the power supply common (ground) connect to the tuner's common (ground)...yes, it should.
Mike
Mike
I had two diodes reversed, everything is working even with grounds tied together. To my ears the sound was identical with or without the dedicated power supply. Without the ground to chassis from power supply, the audio quality is quite different out of the opamp. There is more high end clarity, but with some added distortion. It was as if a veil was taken off the sound, which I kinda digged.
What is the significance of having B+ to pin 4 of OPA2604?
What is the significance of having B+ to pin 4 of OPA2604?
Do have, or have access to a scope or an analyzer with FFT capabilities? That will show you exactly how much or how little distortion is being generated. Sometimes added distortion will masquerade as more detail, but becomes fatiguing to the ear relatively quickly.
Mike
Mike