OD trim #124

[grtamp]

Hi , anybody have try 250K OD trim in #124 ?

[odourboy]

https://tubeamparchive.com/viewtopic.php?t=11568

[ChrisM]

I think he is talking about the the pregain trim Brian.

250K would work fine, probably better than 350K. The stock 350K trimmer is hardly padded down, and with such a high resistance it makes the control very fiddely and sensitive. You could replicated the 350K pregain trim probably by lowering the series resistor before the pot.

[jelle]

I like 100k.

[guitardude57]

+1 on the 100K

[grtamp]

Yes , I am talking the OD trim pre-gain!.

I'd like try 120K res with 250K trim...what do you think?

[Structo]

I think as long as your chain of resistance approximates 320K you are loading the OD entrance properly and will attain a good OD saturation.

On my amp I ended up putting a 50K pot on the back panel.
On the board there is a 220K and 47K resistor in series.
This makes the middle part of the rotation of the pot on back from 20K to 30K wiper to ground, which most agree is the zone you want for the OD trim.