Squier JM JM rewire. Not what I expected!

[Monty1]

More of a conversation piece rather than a 'how do I' post.

Just rewired my Mascis JM , vintage cloth cable (because I like working with it rather than any tone claim). Basically followed the Fender 1962 diagram with 1m pots (replacing 500k) and 0.033 cap on lead (orange drop, they're cheap and consistent rather than any magic tone shite claim), 1m and 50k pots and 0.022 cap on rhythm. All pots are very close to spec on the multimeter as are the caps.

The cavity was already painted with conductive paint, but my multimeter didn't reckon it was especially conductive so I copper foiled it. Pick guard is ally and already shielded with ally foil, multimeter confirms that between ANY two points the resistance is 0 ohms apart from the bridge which is less than 1 ohm.

All switches and stuff work exactly as expected.

But, the tone has become a tiny little bit darker than it was with the 500k pots which is not what I expected or hoped for. Clarity is good, the middle position is appreciably fatter, but it's not brighter and if anything the bridge sounds a little thinner than it did.

Easy enough to pop the 500k's back in but any thoughts? I suspect putting the 500's back will make it darker.

Thanks

Monty

[timtam]

The cavity was already painted with conductive paint, but my multimeter didn't reckon it was especially conductive so I copper foiled it. Pick guard is ally and already shielded with ally foil, multimeter confirms that between ANY two points the resistance is 0 ohms apart from the bridge which is less than 1 ohm.

The performance of conductive paint is confusing because it seems that it is never perfectly conductive, ie zero ohms between two points. Such paint is specified in ohms per cm, and the specs never say anything near 0 ohms per cm. And so even with the best paint the resistance between two points will often be in the tens of ohms. Whereas foil will show zero ohms. Just what that means for shielding performance is uncertain, as there is no easy objective test we can do. But it's unlikely that point-to-point resistance equates directly to shielding performance (or no companies would be using paint) ... so we can't conclude that foil is better than paint.

[Embenny]

My experience has been that a good shielding job cuts down some high frequency content. That might be what's responsible for your tone change.



The other thing is that 1meg pots just increase the size of the resonant peak. They don't add "brightness" per se...it all depends on where your pickup's resonant peak lies. The JMJM pickups are P90-construction and have lower resonany peaks than vintage JM pickups, so you may in fact be hearing higher midrange content where the peak lies, in addition to less highs from the shielding.

Midrange is often perceived in pickups as "fatness". High mids are often "brightness" and highs are often "harmonic complexity". You likely boosted some mids (possibly at different points between the two pickups) along with cutting some highs. You could always put a 500k back and see where that gets you, but the copper shielding likely will make that sound a little darker than you remember, as well.

[Monty1]

Thanks for the replies chaps.

@timtam. Yep agree with your point, I've no idea at what point shielding becomes effective or non effective just by taking a meter reading. I was getting quite a variation in resistance from a few k ohms to about 50 ohms. Had a load of tape to hand so decided to copper it anyway as it had been a little buzzy especially when near to dimmer switches and the like. It's now 99% silent on the EMF noise side, what noise I am getting is mostly being picked up by the cable and amp rather than the guitar. It is genuinely 0 ohms (subject to the accuracy of my £20 multimeter!) so I guess it's as shielded as you can get now.

@mbene Hadn't contemplated the shielding cutting down the highs, but yes I think I have a slight shift in the mids which is evident in the middle position so relatively speaking the highs sound suppressed and the tone gives the impression of being less bright. That fits with what I'm hearing, so I've learnt something today. But the mids seem to be suppressed on the bridge hence thinner tone so that would suggest the resonant peak is different between neck and bridge pickups (which given they are probably wound differently would tally with your response) so they must be interacting in the middle position because it is notably fat. It's actually really good in the middle position which previously was a bit dull.

This may explain my Firebird as well. The crapo Gibson pots went crackly so I did a complete rewire (kept all values the same but went with Bourns pots, orange drops and cloth wire), replaced the PUP selector and output jacks that were PCB types with switchcraft. At the same time I shielded it, it wasn't noisy but I though I might as well whilst it was bare bones. It's a recent FB with ceramics that get a bit of a slagging but they've mellowed as a result of the work. Far less prone to ice pick and more prominent/clearer mids/upper mids to the extent that my tutor asked if I'd swapped out the PU's. If shielding can drop out some of the highs then I would probably go with that as part of the reason. Not massively different, but different enough to raise the question. I hadn't contemplated shielding being a contributor and we'd just assumed it was the sum of many very small incremental changes. He wasn't fond of the FB tone before but the neck is now very playable, the jury is still out on bridge but it's much nicer than it was.

I'm going to stick with the 1 megs in the JM for a while. Don't know much about guitars, and I can't play for chips TBH but I think you always need to run something for a while to get accustomed to it and potentially re-learn your amp settings before you abandon the change (unless it's absolutely dire). Bunging the 500k's back in is a 10 minute job but I'll probably wait until the strings go off to give it a fair chance. I am digging the middle position though

[601210]

I didn't realize the original pots were 500k -- I swapped the stock pickups out to a different guitar with 1Meg pots and thought they sounded way higher output than I remembered them sounding.

Now I feel like an idiot after ordering another set of JM pickups and leaving the JMJM ones as orphans once more .

[Monty1]

The ones that came out of the JMJM were 500k, stamped as such and measured about 490k from memory but who knows, these things do seem to vary occasionally component wise. I did swap them out with 500k CTS early on because they'd started crackling, put an orange drop in the lead circuit and bunged in a switchcraft 3 way selector (the original was intermittent) but kept all of the original wiring and left the rhythm circuit well alone. No tone difference before or after, just less crackle and reliable switching.

Getting to grips with it now, scooping it much more than I normally would (I don't really like scooped) gets it close to what I was expecting. For whatever reason the mids have been boosted (or everything else is lesser) after the rewire, 1m pots and shielding.

If there's ever a nuclear war the only things to survive will be cockroaches and whatever is in the cavity of my JM such is the level of shielding achieved

[pikmin]

I just changed the pots in my JMJM and the original ones were 1meg !!!

[Monty1]

Thought I'd post an update. A bit of time spent mucking about with amp settings made a slight improvement but eventually I manned up and replaced the 10-46's with 11-49's, spent an hour amusing myself with my truss rod and nut (after which I returned to doing guitar stuff), put an original Fender spring in the Squier trem and it's now exactly what I hoped for apart from the rattly/fally outy trem arm. Got the action fairly low and it plays superbly, zero fret buzz, the occasional rattle from the bridge has gone and the tone is full and rich and has that JM brightness that I wanted. After a search here I've now learnt that rolling volume off a tiny amount warms and thickens up the bridge if you need it. Very happy with the outcome, 11's are the way to go and they actually feel much lighter than they should, certainly much lighter than my Gretsch 5420 that's running exactly the same strings. Tuning seems more stable as well. For about £30, a bit of effort on my part and the collective wisdom of this site it now feels and sounds like a much more expensive guitar. Learning stuff is fun so thanks to everyone that has contributed to this and other threads from which I drew knowledge, this is an excellent community.

*Newbie cock up* Managed to disengage brain, I used a schematic on the allparts site to order up all of the replacement electronics and they show the tone pot as being a taper which I ordered despite having a Fender schematic showing both as linear. Doh! Taper is a bit rubbish TBH, tone goes from bright to dark almost instantly at about 3, from 10-3 there's almost no change. I've got a linear that I'll solder in next time I change the strings.

[MechaBulletBill]

I find that 500k pots (and probably 1m but it's been a while since I messed with them) have a weird and kind of annoying taper vs 250k

[Monty1]

Yeah, the 1m taper tone is more or less a switch on my JM. The 1m linear volume is fine, it rolls off in a very natural way.