"Faking out" a 250k pot for HSS via resistor - any downsides?

PonchoGreg

Got an HSS config with just the one 500k volume pot for all three pickups.

It's mostly fine because the singles in question are quite pokey to start with (SD SSL 6), but it's still a bit harsh/sparkly to my taste. I really like the low-friction 500k pot (and it sounds good with the humbucker) so ideally I'd rather keep it.

I've been reading about the resistor method, and was thinking I could try and "fake" a 250k (or 300k) pot for the single-coils with either a 470k or 750k resistor.

Is it as simple as running the resistor to ground from the pickup connections on the switch (in parallel)?

But more importantly, are there any negative impacts on the taper and general behaviour of the volume pot?

Thanks guys!

ICBM

You need to add the resistor to the other side of the switch, where the tone controls would normally connect, or both neck and middle will be on when either is selected. If there are two tone controls you’ll need to swap one to work on both single coils (connected to where the resistor is) and the other on the humbucker alone.

There’s no change to the pot taper because the resistor is in parallel with the whole track, not just one half of it. You may get a tiny bit more treble loss as you turn the volume down because the resistance above the rotor rises faster.

PonchoGreg

Awesome, very helpful thanks. I actually need to take a closer look at the wiring as it's a superswitch (and just the one tone), so I'll need to figure out how it all interacts together

PonchoGreg

Mmmh took a peek and it's actually a pretty simple circuit (owing to the lone tone control, I imagine).

 
Basically one pole for the single coils, one pole for the humbucker (and middle for position 4), and one pole to handle the auto-split for the bridge humbucker (sending the split either to ground or hot). Leaving one pole totally unused.

With that in mind, my thinking is to run one resistor each from the mid and neck connections on pole 1 to ground.

But then I think that might wreck havoc on the "combined" positions. For instance, I would imagine position 4 (N+M) will see a damn sight less than 250k with two resistors in parallel.

Will have to ponder that (or better yet just try it out as it's just a simple solder job).

ICBM

That makes it even easier - use the spare pole. Connect the rotor to the two rotors on the left that go to the volume control, connect together the positions you want with the lower resistance - everything other than the bridge position - and connect that to the ground on the other side of the switch.

PonchoGreg

Of course! Makes total sense.

I might try just the one resistor on the neck pickup first to make sure I like it (and maybe try a couple of different values to fine tune) and then implement that if I like the result. To be honest it's mostly the neck pickup that could do with a bit of taming. The combined positions are pretty spanky/bright but that's no bad thing.

Thanks a bunch @ICBM ;

ICBM

The great thing about using the fourth pole is that you could actually have a different resistor value for each position, if you want!

PonchoGreg

Indeed - the superswitch really is a great design

(I also find it much easier to visualise than the standard 3 or 5 way for some reason!)

It's a shame about the slightly mushy action (of the Oak Grigsby or similar, at least). I wonder if someone makes one with a nice, clicky feel like a spring-loaded CRL... Might not be possible with the 2-wafer design though.

ICBM

CRL do a superswitch - https://www.banzaimusic.com/CRL-5-Way-Super-Switch.html

sixstringsupplies

ICBM said:

CRL do a superswitch - https://www.banzaimusic.com/CRL-5-Way-Super-Switch.html

There is no such thing as a CRL superswitch. This is an innocent error made by Banzai music and the occasional Reverb/eBay seller in their product description.

CRL and Oak Grigsby switches are two separate brands both of which are owned and manufactured by Electroswitch in North Carolina.

This is 100% an Oak Grigsby switch - but as they are made by the same company, *some* companies get confused.

You are not getting ripped off, the price is fine and standard for an Oak Grigsby super switch. Anywhere from £20-£25 is an acceptable range.

However, there are several versions of the superswitch by Oak Grigsby. (At least 4 on the website, but we have just ordered one that is not on the website, so I assume at least 5!)

Sorry to be pedantic....but thought you should know.

This is the CRL selection available from the factory: https://www.electro-nc.com/crl-guitar-switches

The switch on the Banzai website is p/n 51970 on this page https://www.electro-nc.com/oakgrigsby-guitar-switches

We have just ordered a newer version of the superswitch from the factory, which is known as the "skinny" superswitch as many vendors/luthiers complained that the standard superswitch is too beefy/wide to fit into many guitar cavities (Telecaster being the classic example) so they released the "skinny" superswitch.

ICBM

Good information, thanks .

I thought the wafers in that switch looked very Oak Grigsby... wondered if they'd used the wrong pic.

sixstringsupplies

ICBM said:

Good information, thanks .

I thought the wafers in that switch looked very Oak Grigsby... wondered if they'd used the wrong pic.

No worries! No I’m sure the picture is correct and if you ordered it, that is what would arrive. They’ve just used the incorrect description. Innocent error. 

Van_Hayden

Fender part number 099-0847-000 is a dual 250/500k pot ideal for this application although it's not particularly low friction. 

ICBM

Van_Hayden said:

Fender part number 099-0847-000 is a dual 250/500k pot ideal for this application although it's not particularly low friction. 

I really don't see the sense in using a specialist part and a more complex wiring scheme, when you can do the same job with a single resistor that costs pennies. You would also need another spare pole on the switch, to switch both the inputs and outputs of the pot.

PonchoGreg

Tried with a 680k (after a WTF moment until I realised I was using a 680r... Proper facepalm). It's pretty subtle, but nice. Might bump it up to 470k.

CasperCaster

@ICBM I have a couple of the switches from Banzai and it comes in Allparts packaging with their part number, and is in fact an Oak switch. I still have one unopened somewhere.

ICBM said:

Van_Hayden said:

Fender part number 099-0847-000 is a dual 250/500k pot ideal for this application although it's not particularly low friction. 

I really don't see the sense in using a specialist part and a more complex wiring scheme, when you can do the same job with a single resistor that costs pennies. You would also need another spare pole on the switch, to switch both the inputs and outputs of the pot.

Partly agree. The wiring diagram for this pot is on Fenders website and they use the pot in a sort of send and return from the switch, and use a 4-pole switch where one half (2 poles) is a standard 5-way and the other half is a superswitch. Stupidly complicated. However, it is great on HSS shredder guitars with a single volume and tone, where it can be used for tone, so the singles see 250k/47nF and humbucker 500K/22nF. I know you feel 250k is fine for humbuckers in a Strat, and sometimes it is (a JB for example), but the dual pot has its uses with some pickups/guitars, and they aren't particularly expensive. 

A good example of the 470K/510K resistor mod is drawn out at the bottom of this article:

http://www.guitar-mod.com/strat.html

PonchoGreg

There was actually a bit of thought put into the component selection for the guitar I was working on (charvel DK24, HSS).

It's only got the one volume and one tone, both 500k. The tone cap is actually a 47nf.

But the humbucker is an SD Full Shred, which is pretty scooped/bright. So the 47nf actually works pretty well. And the singles are SSL6s, which are hotter/darker given the wind and wire. So the 500k pots are actually not too mismatched, and in any case the 47nf cap helps when winding down the tone a bit.

I'm playing around with the resistor because I tend to like a smoother neck pickup, but it is perfectly usable in stock configuration. If anything, the one choice I'm not too sure about is the no-load tone pot. It's good for the humbucker in a raw, 80s tone sort of vibe as it is indeed bright and snarly on 10, but the single coils do benefit from the extra load when putting it just below 10 (so it's back in the circuit).

Again, totally down to my own preference though - the stock config is a very good compromise.

ICBM

CasperCaster said:

Partly agree. The wiring diagram for this pot is on Fenders website and they use the pot in a sort of send and return from the switch, and use a 4-pole switch where one half (2 poles) is a standard 5-way and the other half is a superswitch. Stupidly complicated. However, it is great on HSS shredder guitars with a single volume and tone, where it can be used for tone, so the singles see 250k/47nF and humbucker 500K/22nF. I know you feel 250k is fine for humbuckers in a Strat, and sometimes it is (a JB for example), but the dual pot has its uses with some pickups/guitars, and they aren't particularly expensive.

[Repair tech hat on] It also adds unnecessary extra potential reliability issues - the signal path has to go through two extra switch contacts. The advantage of 'faking' it with an extra resistor is that it's simply added in parallel, and if the contact fails then the tone correction simply doesn't happen... but the guitar keeps working. I also expect that the send/return scheme causes a lot worse switching noise.

For a single volume and tone I would just use a 500K tone pot with .022uF cap - with an extra 470K resistor and .022uF cap in series, in parallel with the 470K resistor - added to the 500/.022 that gives 242K/.044uF, which will be extremely close to 250K/.047uF. As you roll the tone control down it will revert to the .022uF at the bottom of the travel, which is effectively what the Fender 'Greasebucket' scheme does.