Guitar Fetish XGP Potentiometers

I have recently, after a very long hiatus, gotten back into playing guitar. My 4 year old son has prompted it with his excitement over some of the music I love, especially Zeppelin, ZZ Top, ABB, Rory Gallagher, etc. He has really taken to that style of music and it's been very fun watching how excited he is. We bought him a super budget brand guitar last Christmas, one of the little short scale ones with a built in speaker, and I took a peek over at GFS because I want to upgrade it a bit for better playability and sound.

I am used to the type of quality of product they have, i.e. I like their stuff for upgrading beater guitars and getting better tone out of them for a good price. When I used to play more often I had a little side thing where I was upgrading starter guitars with these components for people and for the most part the stuff is pretty middle of the road, tonewise.

I was looking for full size pots so I could add a tone control to my boy's guitar and came across these:

http://www.guitarfetish.com/XGP-Custom-Taper-Split-Shaft-Pot-A500K-Humbucker-Volume-Our-Best-_p_22992.html

Now I am used to the type of pot they sell at GFS: generic Alpha pots. These pots still look to be Alphas, but with brass shafts. They do however say "Custom Taper". That piqued my interest, as I am always interested in finding pots with vintage correct/desirable tapers. I decided that I would shoot an email over to their tech staff and see if I could get more information. I asked if they could provide a cut sheet for the pot that showed the taper ratio. The quick response back was that they didn't have that information at their disposal.

I pushed back a little bit due to the fact that they are marketing them as having a custom taper, and as such would have to have provided the manufacturer with a custom specification for production. I got another reply with more information. Evidently the "custom" actually refers to the brass shafts, bushings and carbon wipers. Interesting though, the standard ratio for the audio taper pots is 60:40.

I have a set of 250k pots coming for my son's guitar. I'll measure them and determine the actual taper when they get here.

Received these last night and installed them in my son's short scale guitar. I received 2 250k pots (both measured within 2% at 246k) and while I did not do a full measurement (20 readings during the rotation), the 10 I did take show the pot to be somewhere between a 60/40 and 65/35 taper. As such the sweep from about 0-6 was nice but provided only subtle variation, while 6-10 gave noticeable boost at each step. The pots themselves felt solid but are rather light and a bit cheap feeling (think typical Alpha pots but with more rugged shafts and internals).

For $3.50 each these may be of use to some people looking for a solid, inexpensive pot with a good taper.

Your assumption that the "vintage" taper is from an Audio aka Logarythmic taper is actually wrong.

Gibson taper in Volume pots in the "vintage" years, when they were using Centralabs pots have always been Linear. It's even specified in all available spec sheets of every single instrument Gibson ever built.

So, no need for "fancy" taper. As long as it is linear, any brand of pot should do fine and make you feel at home, so to speak, taper-wise.

And TBH, stock Alpha pots are NOT as bad as most think they are. In the most recent years of manufacturing in mainland China in a brand new, ISO 9000-compliant factory, their quality and reliability REALLY went up. Specially their small-format pots, which in the past, and with good reason, were considered tone-killers.

HTH,

LtKojak said:

Your assumption that the "vintage" taper is from an Audio aka Logarythmic taper is actually wrong.

Gibson taper in Volume pots in the "vintage" years, when they were using Centralabs pots have always been Linear. It's even specified in all available spec sheets of every single instrument Gibson ever built.

So, no need for "fancy" taper. As long as it is linear, any brand of pot should do fine and make you feel at home, so to speak, taper-wise.

And TBH, stock Alpha pots are NOT as bad as most think they are. In the most recent years of manufacturing in mainland China in a brand new, ISO 9000-compliant factory, their quality and reliability REALLY went up. Specially their small-format pots, which in the past, and with good reason, were considered tone-killers.

HTH,

Click to expand...

I wasn't assuming that at all. I have always just been under the impression that the vintage pots split the difference between modern linear taper and modern audio taper, i.e. the oft quoted 60:40 or 70:30 taper of the vintage pots found in the 50s and 60s Gibsons.

With that said, I have had great luck in the past with straight linear taper pots. I always gravitated towards the Bourns minis as I like the feel and throw of those. Very smooth.

Ultimately though, are you saying that the old Centralab pots did not have 70:30 tapers as is often quoted? Definitely not doubting you I've just never heard that. I know the modern era Gibsons come with linear tapers but wasn't aware the vintage units did.

I think for me its just a matter of getting a nice even sweep from 6-10. I'm not enamored with a specific taper to get that.

LtKojak said:

Your assumption that the "vintage" taper is from an Audio aka Logarythmic taper is actually wrong.

Gibson taper in Volume pots in the "vintage" years, when they were using Centralabs pots have always been Linear. It's even specified in all available spec sheets of every single instrument Gibson ever built.

So, no need for "fancy" taper. As long as it is linear, any brand of pot should do fine and make you feel at home, so to speak, taper-wise.


HTH,

Click to expand...

I've no dog in this hunt..Just asking this for clarity.

This is the wiring diagram for the Gibson ES-5 Switchmaster, From Gibson's own online archive.

Is the "500K Audio" listed as the spec for the controls incorrect from what was actually used or am i confusing things?

chasenblues said:

I've no dog in this hunt..Just asking this for clarity.

This is the wiring diagram for the Gibson ES-5 Switchmaster, From Gibson's own online archive.

Is the "500K Audio" listed as the spec for the controls incorrect from what was actually used or am i confusing things?

Click to expand...

After perusing the same archive, the records seem to indicate that many of the instrument from the mid 50s to the early 70s all used audio taper potentiometers. It makes sense especially considering how the controls respond with a pot in the 60/40 or 70/30 taper. Modern audio pots are on/off switches from 8-10 and linear taper pots can sometimes be too subtle for variations.

Well, looks like my notes are wrong... that's embarrassing, to say the least!

The specified pots on the old Gibsons indeed are Audio. There are many other schematics with NOT specified pots, but if the others are audio, logic dictates those to be audio as well.

The 300K linear pots apparently did come with the Norlin takeover.

So I stand corrected. Apologies for the incident.

Yours very truly,