bias pot query

Will an Alpha or a PEC bias pot with its 314 degree turn be fine enough for setting bias? I use a small Bournes multi-turn pot now which dials in bias quite nicely. I like the idea of a larger chassis mounted pot for a new amp build, but wonder if they can handle the job with D. Gillespie's EFB.

Captain Coconut wrote:Will an Alpha or a PEC bias pot with its 314 degree turn be fine enough for setting bias? I use a small Bournes multi-turn pot now which dials in bias quite nicely. I like the idea of a larger chassis mounted pot for a new amp build, but wonder if they can handle the job with D. Gillespie's EFB.

like the standard one turn trimmers, it works, but of course you will get finer adjustment out of multi turns. Have you looked at larger multi turn pots, they cost more, but are generally the same size as your average every day pot.
Here is one option https://www.bourns.com/ProductLine.aspx?name=precision_pots_multiturn

I have a PEC pot in my ST35 with EFB. Works just fine.

You can get some nice "bourns" 50k multi-turns offa da bay for $6 each - including the locking knob and wrench ...


I got a five pack of those a while back just for shitzengiggles and tested them on the meter ... solid build, smooth movement, within tolerance, and they all track accurately throughout the range.

Thanks for the input fellers.

Hi sKiZo --- do you remember the "seller at the bay" that you dealt with?  

I just checked for "Bourns 50K multi pot" and "Bourns 50K pot locking knob" but I did not see any with the locking knob and wrench.  I found the bottom part of the pot but they were not $6, more like $20 to $40+.

Any insight would be appreciated.

Thanks,
Stew

5ps 50K Ohm 3590S-2-503L With Turn Counting Dial Rotary Potentiometer 10Turn

These will actually be the third set of pots in this build. First ones were cheepo Chinese - one of those went open and dusted a tube and bias resistor. Currently running some really good Fender pots, but those aren't true linear and get a bit tweaky right where I need them. I figure the 10 turns should dial right in.