Hello 🙂 I am seeking advice with my yamaha a-1000. I am not sure if it is just my piece or it is standard behavior of this amp, but the sound from the stock preamp is really not nice. It has a really flat sound on mid/high frequencies. But the situation is completely different when I put the input signal directly to the main amp. It started to produce a really nice sound, not boring, not liveless, not flat. So I guess that is something not 100% allright with a preamp. I changed 4x caps (highlighted) on the preamp board. Also cleaned the DIRECT switch, MUTE switch and did measurement on other signal switches, all looks good. Both channels have the same ** sound, so I hoped that IC M5219L is not good, so I swapped it for another(from the main board) but unfortunately it didn't help. Voltages on IC are correct.
Input voltage to the preamp board is +21.5V and - 18.9V (should be +-22V). But I guess that this is not problematic because this is also voltage supply for the IC on the main board (main board sounds great, also on DBT when voltages are even lower).
What else should I try ? Change M5219L for something different (opa2604) and hope that will be better ? Throw a preamp (they call it flat amp, yes I agree 😀) in the trash and use just the main amp ? 🙂 Thank you for your ideas 🙂
Input voltage to the preamp board is +21.5V and - 18.9V (should be +-22V). But I guess that this is not problematic because this is also voltage supply for the IC on the main board (main board sounds great, also on DBT when voltages are even lower).
What else should I try ? Change M5219L for something different (opa2604) and hope that will be better ? Throw a preamp (they call it flat amp, yes I agree 😀) in the trash and use just the main amp ? 🙂 Thank you for your ideas 🙂
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I ordered 2xopa604 and 2xso8 to sip8 adapter. But I am not sure if this can help. I have also yamaha a-1020 (no IC on signal path), when I compare those amps.. day/night difference. A-1020 has superb sound. I don't believe that there should be that huge difference, when I compare stock amps.
Hi, problem solved. When I put 2x opa604 inside, no big difference happened. Solution was really easy. Last step that I didn't do was clean the volume pot. There wasn't any trouble with it, no scratch noise, nothing wrong. But when I sprayed it with pot cleaner the issue disappeared. I never faced a similar issue.