Strat Wiring

Nomad

I'd like to replace the electrics in my shiny new second hand MIM strat. It has what look to be decent aftermarket SSS pickups with A5 magnets and DC resistances of 6.2K neck & middle, 6.7K bridge. Got a few questions that I'd appreciate feedback on...

Fit all 250K log pots?

What difference does it make to change from one tone cap to two?

Any particular value(s) for the tone cap(s)? I have 0.022 and 0.047 uF orange drops. I'm not looking for especially bassy sounds, more a mellowing of the tone, so I'm guessing 0.022.

There's quite a lot of treble loss when I turn the volume down - can I do a 50s style wiring without affecting the basic switching and functionality?

I'm thinking of adding two mini toggle switches, one to force the bridge pickup on, and one to route a tone control to the bridge from one of the other pickups. Would either of these impact a wiring scheme with the above features?

ICBM

Nomad said:

Fit all 250K log pots?

Yes.

Nomad said:

What difference does it make to change from one tone cap to two?

Two caps means you can use different values for each pickup, and you can simplify the switching (to make it more reliable) if you want. The disadvantage is that in the neck/middle position, both caps are connected so you get a duller tone.

Nomad said:

Any particular value(s) for the tone cap(s)? I have 0.022 and 0.047 uF orange drops. I'm not looking for especially bassy sounds, more a mellowing of the tone, so I'm guessing 0.022.

I prefer .047 for Fenders - it gives a softer and less middy tone - but you can try both and see which you like. Or you can use .047 for the neck and .022 for the middle.

Nomad said:

There's quite a lot of treble loss when I turn the volume down - can I do a 50s style wiring without affecting the basic switching and functionality?

You have to wire the switching differently, but it can be done if you want.

A treble pass cap on the volume control is more effective though.

Nomad said:

I'm thinking of adding two mini toggle switches, one to force the bridge pickup on, and one to route a tone control to the bridge from one of the other pickups. Would either of these impact a wiring scheme with the above features?

You can add the middle tone control to the bridge pickup without a switch, and/or convert to a master tone control with a bridge-pickup blend using the other control.

Mini-toggles are too 1980s and should always be avoided .

Funkfingers

Nomad said:
I'm thinking of adding two mini toggle switches

It is tidier-looking and more ergonomic to achieve this with push-pull pots. I usually add just one. It invariably goes under the upper (neck PU) tone control. 

Nomad said:
one to force the bridge pickup on

I do the seven sound mod with the neck PU as the one that gets switched in and out. This reduces the amount of frantic pushing, pulling and turning when switching between certain sonic permutations. 

Nomad said:
one to route a tone control to the bridge

You can have the lower tone pot apply to the bridge PU by either of two methods. 
1) Shift the wire running between the lower tone pot and the selector switch along one to the unused lug on the switch.
2) Add a jumper wire between the existing connection and the unused lug - à la modern Fender circuitry.

Nomad

Thanks both.

I think I need to gain a better understanding of what happens in the 5-way switch - I currently have no idea what terminals are connected in each position. It sounds like there may be wiring methods that I'm not conceiving because I don't know what additional possible options the switch offers.

Don't know what the problem is with mini toggles. I fitted two to my Gibson Marauder (for phase and coil splits), next to the pickup selector on the lower horn, all running horizontally, and it's very easy to use and see the current settings. I'd have thought a mini toggle operating along the same direction as the 5-way would be pretty easy to use and see. The Marauder switching was done in the 80s.

It occurred to me that I could use a single 2-pole changeover to both route the neck tone to the bridge and to force the bridge on. That way, with the 5-way set to bridge only, I have tone on the bridge, and set to neck only, I have both pickups and still have tone. Am I right in thinking that could be done?

@ICBM, the treble pass is fine by me if it maintains the tonal balance reasonably well. I was looking around and saw something that suggested a 1nF cap in parallel with a 150K resistor, wired between the hot signal and the volume pot wiper. I was going to ask if that sounds about right, but then found some page that talks about having them in parallel or series, as well as having just a cap. Does the treble loss have something to do with the wiper/ground side of the volume pot reducing in resistance in parallel with the cable capacitance?

ICBM

By far the easiest way to get a tone control on the bridge is to link the unused terminal on the switch to the next one - that also means that if you use two different caps, it shares the value with the middle and not the neck, which is usually better. There's no need to make things more complicated by switching the tone controls as well.

The treble loss when you turn down is actually caused more by the *upper* part of the volume control track being in series with the output while the cable capacitance is in parallel with it, rather than the lower part being in parallel.

Nomad

ICBM said:

By far the easiest way to get a tone control on the bridge is to link the unused terminal on the switch to the next one - that also means that if you use two different caps, it shares the value with the middle and not the neck, which is usually better. There's no need to make things more complicated by switching the tone controls as well.

Fair point. I'll see how I get on with tone settings, although I suspect you may be right that the middle is more like to be the one that's shared (and is arguably more intuitive for knob twiddling).

ICBM said:

The treble loss when you turn down is actually caused more by the *upper* part of the volume control track being in series with the output while the cable capacitance is in parallel with it, rather than the lower part being in parallel.

Is this like one of those RC low pass filters that I was probably taught about a number of decades ago and have long since forgotten? I did some searching and found 1 / ( 2 pi R C ), which gives a curve where the cut-off frequency reduces as the resistance increases.

ICBM

Nomad said:

Is this like one of those RC low pass filters that I was probably taught about a number of decades ago and have long since forgotten? I did some searching and found 1 / ( 2 pi R C ), which gives a curve where the cut-off frequency reduces as the resistance increases.

Yes, and it's further complicated by being in series with an inductance - the pickup coil - which also halves when two pickups are on at the same time.

A passive electric guitar is a nightmare from a frequency response point of view! Particularly given that electrically speaking, the cable is part of the guitar circuit...

Funkfingers

Nomad said:
I suspect you may be right that the middle is more like to be the one that's shared (and is arguably more intuitive for knob twiddling).

In my opinion, even on HSS Stratocaster type guitars, it is desirable to be able to flip from a mellow neck PU sound with its tone pot rolled off to a brighter pickup permutation for which the tone pot is wide open.

For this mindset, the most practical layout is neck PU = upper tone pot, middle & bridge PU = lower tone pot.

Some HSS users prefer to have neck & middle PU = upper tone pot, bridge PU = lower tone pot. This makes sense if you require a different value pot or capacitor network dedicated to the humbucker. In all other respects, it is a drag to use.

normula1

I always rewire mine so that the upper tone control is for neck and middle pickups and the lower for bridge only.

If a guitar has a super switch in it (which most of mine do) I wire it such that when the bridge and middle pickups are selected only the upper tone control functions i.e. the lower tone control only functions when the bridge pickup is solo'd

And lastly one of my guitars also has an S1 switch that I've wired so that the down position changes position 4 (neck and middle) to neck and bridge when the S1 is pushed in and this is also then controlled by the lower tone control.

I do tend to knock the bridge tone control down a notch and this method works perfectly for me. Your mileage may of course vary

Nomad

Just rewired it (and fitted poncy tart-up plastics that aren't black).

I went with the lower tone control doing middle and bridge, fitted a 1nF on its own for treble pass, and routed a pair of wires through to the trem cavity with a little switch dangling off it to try the bridge-always-on thing. Pots are all 250K log, and the tone cap is a 0.022uF.

I've still to try it through the big amp, but initial impressions through the THR10 are that I think I'm happy with the middle and bridge sharing the lower tone control. The treble pass seems to make it too bright when the volume is turned down. So far, the new combinations with the bridge on don't sound especially exciting. I still need to set the pickup heights, though.

Funkfingers

Nomad said:
I've still to try it through the big amp. The treble pass seems to make it too bright when the volume is turned down.

Once you have the pickup height adjustments set, try the guitar at stage volume. Also, try in a full band context. (Playing along with a backing track would do.) 

Nomad

Funkfingers said:

Nomad said:
I've still to try it through the big amp. The treble pass seems to make it too bright when the volume is turned down.

Once you have the pickup height adjustments set, try the guitar at stage volume. Also, try in a full band context. (Playing along with a backing track would do.) 

I don't see what difference this makes to playing solo stuff at home. The fact is, it's too bright when turned down and needs to change.

Nomad

'Tis done.

In the end, I decided to not add the additional pickup switching for now. Although I was mainly interested in the bridge and neck sound, I found it was a bit lacking in character, and thought the all-three sound was more interesting (mainly for funky chords rather than melodies). Overall, I think the main strat sounds are plenty to be going on with and I'd prefer to not have to add a switch or push-pull pot just now to get the other two. That's not to say that it can't happen in the future, but I'll stick with the five for the time being.

I attempted to crunch some numbers regarding the treble pass, but have no idea if what I did made sense (or whether I correctly understood what I was looking at). In the end, I went with a 120K resistor in parallel with the 1nF cap, and the difference was night and day - the balance between high and low frequencies is retained very well when I roll the volume back. Can't comment on what effect it has on the pot taper - I just turn it until it's at the volume I want.

The 22nF tone cap seems fine to me, and only time will tell if I'm happy with it on the middle and bridge pickups rather than neck and middle (too early to be sure). The pickups are indeed the Alexander Pribora Russian-made ones, and do appear to be his Voodoo models - the DC resistances match within a hair. I fitted new 250K log CTS pots and a Switchcraft socket, but kept the original switch.

Here's the scratchplate with the new wiring...

And a close-up of the controls...

Feel free to slag off my wiring.

I also fitted tart-up plastics. Went with Vintage Cream  from Guitars Electric for the plates, and Ivory covers/knobs/tips from Northwest Guitars.

Before...

After...

I'm pleased with the colours - the covers/knobs look a bit more yellowy in the photo than they do in reality. The Vintage Cream is looks about right, and is a bit lighter than in the seller's photo.

I needed to move two holes to get the scratchplate to fit (I drilled out and plugged the originals, then drilled new pilots). I also had to tweak the holes in one of the pickup covers to get clearance for the screws - it seemed that the holes in the pickup flatwork were a little too far apart (two pickup covers had the same issue, but fitted other pickups okay). It was a small tweak with a rat-tail file to extend the holes outwards by about 0.5mm or so.

I still need to address the trem - the arm is very loose. I put some tape on the threads, but it didn't help much after a few waggles. I can't say that I feel it's missing sustain, but I suspect a better arm fitment will come via a new sustain block and arm, so I'm looking into that. Also haven't done any setup other than lowering the action a bit. Not going to mess with that until the trem is sorted.