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    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Can Anyone Tell Me What This Pot Does in AN Soro?

See attached photo. There is a pot in the bottom right corner that doesn't appear in the circuit diagram. Can anyone tell me what its function is?It's on the input board
8qOLL5q.jpg
 
Done somewhat in haste so here's some more details:

1. AN Soro is indeed the Audio Note Soro amp
2. The picture shows the input board and the pot is there in the bottom right hand corner
3. The amp is not mine and I am diagnosing at distance for a friend. If I could see the amp I could work it out in seconds....
4. No pot is shown in any Audio note schematics
5. So I'm really looking for someone with Soro experience to be able to tell me
Thanks
 
Done somewhat in haste so here's some more details:

1. AN Soro is indeed the Audio Note Soro amp
2. The picture shows the input board and the pot is there in the bottom right hand corner
3. The amp is not mine and I am diagnosing at distance for a friend. If I could see the amp I could work it out in seconds....
4. No pot is shown in any Audio note schematics
5. So I'm really looking for someone with Soro experience to be able to tell me
Thanks

Can the schematics be posted here?
 
If you look at the photo link of the Soro in post #8 you will find there is no pot on that board and that since the Oto uses the same input board, also with no pot, it may be special. Maybe if you can get your associate to take a decent photo of the board and the area of the pot you could get a decent answer. It could be a different revision than most and perhaps someone, even you, living in the UK, could just phone AN and ask.
All of the guesses in the world won't get you any closer to an answer.
 
If you look at the photo link of the Soro in post #8 you will find there is no pot on that board and that since the Oto uses the same input board, also with no pot, it may be special. Maybe if you can get your associate to take a decent photo of the board and the area of the pot you could get a decent answer. It could be a different revision than most and perhaps someone, even you, living in the UK, could just phone AN and ask.
All of the guesses in the world won't get you any closer to an answer.

It is of course obvious that there is no pot in the photo in Post 8-noone is questioning that. I also know that other Otos were built with the pot. Not surprisingly I did suggest the owner contact Audio Note who haven't replied either to e mail or phone calls.

As I clearly and politely stated in Post 4 I'm looking for someone with direct experience of the Oto or Soro with this set up who can tell us what its function is, not wild guesses. It's prudent to establish precise function before the not so experienced owner replaces it as it's causing intermittent noise.
 
We received a reply from Audio Note today. The pot was used for balancing the ht voltage between the channels on early OTOs (and probably Soros?). Later models just used the two 20k resistors shown on the schematics that are around as it was largely redundant.

So that explains exactly why when the pot gets noisy it manifests as an intermittent crackle on both channels