Volume control question

[davidjudd2]

I've finally completed my first build. After two home made boards, i bought the PCB from Tube Depot, and it works perfectly. I've heard the 5e3 has a rather limited range on the volume control, mine is no exception. From 0 to 1 it's clean, low level. From 1 to 3 it's a little too loud and starting to break up. From 4 to 12 it's just pure awesome tone, but Way too loud. Is there a way to get more range out of the volume control? I plan on building a power soak for home use, but i was hoping to get a little more control in the lower level clean tones. Thanks, Dave.

[loudthud]

Are you using a 12AX7 as V1? The lower gain of the 12AY7 translates to more usable range at the low end of the volume control.

[Chuck H]

Mouser sells Bourns "guitar" pots. They're 24mm and have a 10% log taper. The smaller taper will give you a lot more range on the lower settings. If the pots you have are 30% log (typical) and 2 is your max clean setting a 10% log taper will expand that adjustment range to max clean around 5. Higher level adjustments obviously become narrower.

[davidjudd2]

I am using a 12AX7, i will try a 12 AY7. I'll look into those pots as well. Thanks for the input.

[pdf64]

Chuck, my impression is that most current audio pots are 10% taper? Weber are the only supplier I've found for 30% vintage style audio taper. I'd be interested to know if you've found any others. Pete.

[Chuck H]

I just measured a couple of Alpha pots I have on hand. The ones EVERYONE uses. The 1M pots are 15%, the 500k pots are 20%. I don't have any 250k pots on hand but I remember needing to buy a Bourns 10% pot to get the taper I wanted because the Alpha pot was about three times faster. I assumed that because the 250k Alpha pot was about 30% that all the Alpha pots were. I haven't had a problem that required tweaking the taper before this so I didn't realize that Alpha uses different tapers for different values.

Since the 5e3 volume pots are 1M I don't suppose there will be much advantage to an A10 pot over an A15 (if the OP's pots are Alpha brand).

[davidjudd2]

Doh!

Well it helps to have the Right taper pots to start with. I had linear "B" pots, instead of audio "A" pots. Much better after the switch. The 12AY7 is much cleaner as well. Thanks again for the help.

[pdf64]

Yes, the taper makes such a difference to the 'user interface'!
Chuck, thanks for checking yours, I went and checked the taper of my 'pot' stash:-
Omeg 1M (UK based, supplier to RS, Farnell and Maplin) ~ 10%
CTS 250k ~ 10%
Alpha 1M ~ 15%
CGE (Mexico) 250k ~ 15%
Weber 1M ~ 25%

The very few vintage BF Fenders I've checked have 30% on the vol and treble, 10% bass and mid.
SF Fenders have used linear for vol.
All the Marshalls I've checked have been 10% vol and bass, linear for presence, mid and treble.
Horses for courses I guess - Pete.