Good Night (for these latitudes).
I have purchased an AIWA P30 power amplifier. I have made measurements in dc output and bias current.
It has a pot to adjust the DC output but not to adjust bias.
The polarization current measurements give 6.5 mV for the left and 3 mV for the right.
The output is with STK 0040 II.
In the service manual it does not say the correct value, but it seems low to me apart from being with asymmetric values.
The integrated circuit STK 0040 II has the possibility of adjusting bias?.
Thank you very much.
I have purchased an AIWA P30 power amplifier. I have made measurements in dc output and bias current.
It has a pot to adjust the DC output but not to adjust bias.
The polarization current measurements give 6.5 mV for the left and 3 mV for the right.
The output is with STK 0040 II.
In the service manual it does not say the correct value, but it seems low to me apart from being with asymmetric values.
The integrated circuit STK 0040 II has the possibility of adjusting bias?.
Thank you very much.
How does it sound?
If it don't burn speakers or bite your ears, it is probably as good as you can expect. It was a low-price amp 40 years ago (though I think it may be better than today's low-price amps). No, the '0040 idle current bias is not adjustable. The open-loop gain is huge (for the price) so the distortion may be tiny. A 3mV difference is insignificant. The offset trim is only because the input JFETs(!) always have some offset.
If it don't burn speakers or bite your ears, it is probably as good as you can expect. It was a low-price amp 40 years ago (though I think it may be better than today's low-price amps). No, the '0040 idle current bias is not adjustable. The open-loop gain is huge (for the price) so the distortion may be tiny. A 3mV difference is insignificant. The offset trim is only because the input JFETs(!) always have some offset.
It sounds acceptably good. It doesn't bite (ha ha)🤣🤣.
I assumed that the polarization cannot be adjusted.
Thank you very much
I assumed that the polarization cannot be adjusted.
Thank you very much
You can't adjust the bias of those darlington output IC. I have same scenario with a Pioneer SX-780 with stk0050. different bias level but no noticeable difference in the sound.