Dual Build: GSJ-1 and GSM-1

[Simon Barden]

Well the 250k pot came and is installed. I thought I'd ordered a linear pot but it turned out to be a log one, and a log was was what I actually wanted, as I always got the actions of log and linear pots confused in tome controls. On a linear 500k pot, I was getting 250k at the mid point of the track between the two normal connection lugs, and 98k at 50% with the log pot.

The 250k log pot is better but still not ideal as most of the action is still occurring below 5, though it does happen more controllable. So what I ideally want is a log pot with more of a curve, so that I get 10% of the pot's resistance at 50% travel rather than 20% of the pot's resistance. And I probably won't get one of those before Wednesday, so it will stay like it is, but I'll note it for future reference.

So in theory:

Audio taper tone = quicker tone roll off
Linear taper Tone = slower tone roll off with more tone roll off at the lower settings.

(If I keep writing it down I may remember it correctly one day).

But certainly with this pickup and capacitor combination, there wasn't a huge amount of audible difference between the linear and log pots. The resistance value required too start hearing some treble roll off is pretty low, so the audio pot is in is more gentle part of the resistance slope by the time it gets there, so it acts in a similar way to a linear pot. There is a small difference between the two, but not a huge amount.

I'll have to do some proper testing.

[Simon Barden]

Tone Pros locking studs arrived and have been installed. For some reason the bridge seems to sit higher and I’ve had to screw the posts right down, which I like but not the lack of adjustment if necessary in future.

[fender3x]

If you are not hearing much difference from 10-5 would it make sense to try lowering the overall resistance of the pot a little more?

I would be tempted to see how it sounds with a 100k resister across the outside legs. That will flatten the audio curve a but it might begin the roll off closer to where you want it...

I have seen charts showing some pretty odd values found in Gibson pots, but I've seen very little explanation of why. What you are seeing might why. Maybe in those days they custom tuned the pots.

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[Simon Barden]

A 100k pot wouldn’t knock much treble off, but it's knocking a small amount off, so I’d prefer to have more resistance available to keep that treble. So a different curve pot is my preferred next try-out, though it will have to be done on a different guitar and I’ll have to find somewhere that sells a suitable pot.

[fender3x]

That's part of why I'd start with a fixed resistor across the legs, to see if the lower treble is audible with the pot dimed. You could start with a 50k and work your way up.

If you want a different curve maybe Mouser or Digikey as a source. Not sure if there is a better source in the UK.

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[JimC]

What happens if you get a two gang pot and put them in series?

[later] nothing special. Don't post when tired and not thinking straight...

[Simon Barden]

Not happy. Effing bridge post holes on the GSM-1 at least 2mm, probably 3mm, too close together. Come on guys, it's not rocket science to drill holes the correct distance apart!

[Rodc]

Had exactly the same thing happen to mine Simon. Talking to a guy on the forum and his was perfect. The EX guitar I built the bridge post where to big. Adam sent some new post but they weren’t much better. 2 were a bit larger but I still had to wrap paper and glue them in. Wasn’t happy!

[Rodc]

Bridge post holes were to big I meant.

[Simon Barden]

It's getting worse. I really don't like this kit any more.

Pickup routs are too big and offset from the proper position. Had hopped to fit the slightly shorter Gibson-sized pickup rings as the enlarged bevels brought the standard neck ring right up to the edge of the bevels. But the smaller rings were too small and I had gaps showing around the edges (which shouldn't have happened if the routs were Gibson sized routs). So I've just fitted the kit neck ring so that the pickup pole pieces perfectly align with the strings, only to find that there's a gap on the treble side because the effig rout's too far on the treble side. So now I've got to fill and redrill those screw holes and have the pickup slightly out just too cover up the hole.

And the bridge pickup doesn't sit properly because the hole to the control cavity is too high and the cables get in the way, so I've got to somehow lower that.

And the scratchplate doesn't fit very well, so there's quite a gap around the pickup rings, so I'll need to make a new one of those.

This really is turd polishing.