Pickup swap

[Rickissippi]

I've always wondered if a pot change (250k to 500k) was necessary for a S/C to H/B p'up swap.....assuming the stock pots are 250k.

Just learned they're 330k. Hmm.... never knew that. So would a 330k to 500k pot change be necessary if going from single-coils to humbuckers? What pots does RIC use in the models that have HB-1s as stock p'ups, like the 650?

Should have dug a little before posting.

Looks like 250k for volumes and 500k for tones on the 650: http://www.rickenbacker.com/pdfs/19501.pdf

And 330k for the four main knobs and a 500k for the fifth knob on a 360/620/381/4005: http://www.rickenbacker.com/pdfs/19502.pdf
As well as a 310/330/610: http://www.rickenbacker.com/pdfs/19511.pdf

Still wondering about the need for a pot swap, though, even if it's just tone knob pots.

[iiipopes]

If you have a 250 kohm tone pot, and you want to find out what minimal effect it will have on the tone to use a 500 kohm pot instead, you can take loose the lug that is soldered to ground and insert a 250 kohm resistor between the lug and the ground.

[aceonbass]

RIC uses the same tone pot (330K) and the same value cap (.047uF) in everything they make these days. 500K pots combined with a cap in a lower value (I like .022-.033uF) will bring out more brightness in HB1 pickups as they tend to sound a bit dull with the stock single coil parts. Volume and tones should be replaced since they're nowhere near 500K to begin with. Oh, and if you're mixing a an HB1 with other RIC single coils, you'll need to reverse the red and blue wires in the pickup lead.

[Rickissippi]

If you have a 250 kohm tone pot, and you want to find out what minimal effect it will have on the tone to use a 500 kohm pot instead, you can take loose the lug that is soldered to ground and insert a 250 kohm resistor between the lug and the ground.

I don't doubt you're right on the money on this, but why do you suppose it is pretty much universally accepted in most electric guitars that you use 500k for HBs and 250k for S/Cs?

[aceonbass]

I agree, although 500K is also kinda standard for tone pots with single coils. The use of 500K pots had more than a minimal effect on Sepps one-off 4004 because he decided to keep it after being dissatisfied with the stock universal electronics.

[iiipopes]

If you have a 250 kohm tone pot, and you want to find out what minimal effect it will have on the tone to use a 500 kohm pot instead, you can take loose the lug that is soldered to ground and insert a 250 kohm resistor between the lug and the ground.

I don't doubt you're right on the money on this, but why do you suppose it is pretty much universally accepted in most electric guitars that you use 500k for HBs and 250k for S/Cs?

http://buildyourguitar.com/resources/lemme/

[Rickissippi]

If you have a 250 kohm tone pot, and you want to find out what minimal effect it will have on the tone to use a 500 kohm pot instead, you can take loose the lug that is soldered to ground and insert a 250 kohm resistor between the lug and the ground.

I don't doubt you're right on the money on this, but why do you suppose it is pretty much universally accepted in most electric guitars that you use 500k for HBs and 250k for S/Cs?

http://buildyourguitar.com/resources/lemme/

I am genuinely not trying to be a smart ***, but how is this link responsive at all to my question? It never mentions 500k pots at all, and mentions 250k pots only once to describe a graph. I still don't know why conventional wisdom is 500k for HBs and 250k for S/Cs, I just know that it is. But I'm not sure *why* it's either conventional or wise.

[Ric5150]

Short answer is that you want the pot to be "a lot bigger" than the pickup resistance to reduce loading and get the signal out of the guitar without creating an accidental and ever-present rolled-off tone knob effect. Humbuckers have more windings and therefore more resistance than single coils. Around double. 500k is "around double" 250k (actually quite close to double )

Notice how you "lose tone" when you turn down the volume knob? Not enough pot resistance. It's similar to signal transfer like low impedance source, high impedance input studio gear type stuff. (Yes, there are tricks to preserve the high end when turning down the volume knob.)

If you draw out the Thevelin equivalent circuit off the pickup....just kidding, I won't go there.

I actually found the link quite interesting and saved a copy of it, but I also have an MSEE degree and 19 yrs experience designing high frequency RF defense electronics. I can certainly understand that the content could have been much less clear to anyone who doesn't.

I think Scott's earlier point was related to what "a lot bigger" comes down to. I don't know off the top of my head what HB1s run, but even if its double a 7.4k scatter wound (15k), 250k is still more than 10X (10X is a common electrical rule of thumb for "a lot bigger"). In a lot of cases, for a lot of ears, another factor of 2 may not make any real difference. All depends on the properties of the pickups, the pots, and to a certain extent, everything else in the signal path.

...that, and whether you can identify the brand of 9V battery installed in your effect pedals like Eric Johnson allegedly can.

What sounds right to you is right to you, whether it matches conventional wisdom or not.

[jps]

If you draw out the Thevelin equivalent circuit off the pickup.....

Cue up CJ!

[iiipopes]

I don't mean to be one, either. I have always learned more by reading the source material than just taking a simple answer, and I suppose I believe others do the same.

Alright, here's the deal:

The higher value the pot, the less loading to ground. The less loading to ground, the higher, both in frequency and amplitude, of the resonant peak of the pickup. So to keep an HB-1 sounding "Rickenbacker," it takes the 500 kohm pots to raise the resonant peak to approach the same as with a high gain or toaster.

The high gains and toasters have less wire on them than the HB-1 humbuckers. This means they have a lower broader midrange peak. The toasters and high gains have less wire, and even though they have different magnets and geometry, each still has a higher resonant peak than the HB-1. So only 250 kohm or 330 kohm pots are needed to bring out the desireable tonality.

Personally, I like a tad smoother tone from my neck pickups on my guitars, so I routinely take a 500 kohm audio taper pot, bridge it with a 1 meg resistor to get a resulting hybrid ramp and effective value of 330 kohms, and use a .033 cap instead of the common .022 cap to roll off a tad more top end when I want to.

[cjj]

Yeah, I agree. If the response curve is the same, it should sound the same...

[Ric5150]

Nice explanation, Scott, and thanks again for the reference. Wasn't trying to undermine the thread, but thought I'd throw the "5 cent" "convention" answer out there.

As you say, there's a lot of merit in diving deeper and optimizing your gear. Rickenbackers are usually decent as stock (though may require adjustments when you swap pickups), but that "conventional wisdom" has lead to a lot of pretty useless tone knobs throughout the industry. I think the "5 cent" answer is as far as a lot of makers go, if not just following convention blindly.