Son of Ben biased but sounds farty

[prsman]

As the title says I have trim 2 and 3 set to 4v and trim one at 2k. (I used the venerable chuck bones method described in another thread).

Still sounds way off. The volume is low and it sounds unbiased. Any points I should check in particular?

 

[jwin615]

Did you select the j201s or just grab some?

 

[prsman]

Did you select the j201s or just grab some?

Just grabbed them. What do I want to look for in them? I've built this a few times in the past with random j201s from the bin. I do have several hundred of them so I wouldn't be opposed to sorting them.

 

[jwin615]

Tried finding recommendations but no luck
There's some good info in this thread

Thread 'Trimpot Adjustment - Son of Ben'

Sep 15, 2019

The build doc says

Is there a way to test trim 1 without removing is from the enclosure?
For Q2&3, is it the same as when biasing a fuzz face? One probe to ground and the other on the drain?

Thanks!

*Edit for future forum searchers* "son of ben" isn't searchable because the words are too long, short, or common. Ha. Here ya go..."Benson preamp"

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Before swapping anything, I'd try biasing by ear. Anything between 3.5-6.5v seems fair game, depending on the particular j201. 4v is really just a starting point.

 

[Feral Feline]

Some people are paying good money for Fart Pedals. Just sayin'.