Advice on blend pots...

Sam Hain · #1 07-09-2011, 07:18 PM

This doesn't relate to bass guitar but rather my dobro...also I have very little guitar wiring experience.

Originally my dobro was wired with 3 controls. Master volume, tone and a blend pot for a piezo and a neck humbucker. The blend pot has a detent in it. My limited experience with blend pots is that they are not very good, at least that's my experience.

Anyways the pots are old and the piezo needs to be replaced.... can I just go with volumes on each pickup(humbucker,piezo) and a tone pot?

Thanks!!

**VincentSalizeri** · #2 07-09-2011, 07:23 PM

Yeah, you can. A blend pot is usually just two regular pots that turn in opposite directions. You need to make sure that the volume pots have the correct values though.

Sam Hain · #3 07-09-2011, 07:28 PM

Now that I think about it maybe I should add a 3 way toggle into the wiring.

Sam Hain · #4 07-09-2011, 07:31 PM

Quote:

Originally Posted by VincentSalizeri

Yeah, you can. A blend pot is usually just two regular pots that turn in opposite directions. You need to make sure that the volume pots have the correct values though.

Are you saying both volume pots need to be both 250k or 500k, not one of each? Also what value pots should I go with? Thanks

walterw · #5 07-09-2011, 08:33 PM

is this a passive instrument?

if so, a blend pot is completely the wrong thing for it; piezos and magnetic pickups do not mix at all, they're electronically like oil and water.

if you want the piezo to sound worth a damn, you need to keep it separate from anything else and run it straight into a preamp designed for it before anything else, pots included.

Sam Hain · #6 07-09-2011, 10:49 PM

Quote:

Originally Posted by walterw

is this a passive instrument?

if so, a blend pot is completely the wrong thing for it; piezos and magnetic pickups do not mix at all, they're electronically like oil and water.

if you want the piezo to sound worth a damn, you need to keep it separate from anything else and run it straight into a preamp designed for it before anything else, pots included.

Yup it's passive and when I'm running both the piezo is almost unheard.

If I'm just running the piezo it sounds great. It sounds like it should, an amplified dobro.

So, I guess to avoid a pre I'll just get a 2 way selector and run a volume,tone and a rotary selector. Not really what I had in mind originally but I think it would work good.

Sam Hain · #7 07-09-2011, 10:53 PM

Actually I just reread your post Walter and see you suggest a separate circuit...good idea. Simple enough too. Thanks.

walterw · #8 07-10-2011, 12:37 AM

fishman (among others) makes a nice little piece for onboard piezo+magnetic buffering/blending/splitting. it's called the powerchip, and it solves all these problems.

Sam Hain · #9 07-10-2011, 05:45 AM

Quote:

Originally Posted by walterw

fishman (among others) makes a nice little piece for onboard piezo+magnetic buffering/blending/splitting. it's called the powerchip, and it solves all these problems.

That looks great...thanks!

SGD Lutherie · #10 07-10-2011, 10:31 AM

I'd second what Walter said. Piezos need a preamp! They have a ridiculously high impedance.

There is a guy who runs the piezo into the magnetic pickup, and that actually sounds pretty good, but for the best versatility, use a preamp like the Powerchip. That will make the piezo sound good, and allow you to mix the magnetic pickup properly.