GR-1SF wiring

[WeirdBits]

There's been a bit of a run on GR-1SF builds recently and several posts asking about wiring, so I thought I'd have a go at a few wiring options. The supplied caps and pots etc. aren't ideal for the traditional wiring layouts of the original manufacturer, but you can make them work. The kit is supplied with (at least in mine):

1 x 3-way toggle switch
2 x A500K (log/audio taper) pots
2 x B500K (linear) pots
2 x 0.047uF capacitors

The traditional schematics use 'A' pots for everything and 0.022uF caps on tone controls. The kit's body is drilled in locations that look like it should have a tone switch, but none is supplied. So, the B pots and 047's represent a challenge, but we can get close to a traditional layout.

This diagram is using stock parts only and has a Master Volume, Master Tone, and individual volumes for each pickup:


The A pots are used on the Master controls, as I'd expect them to be used most, and the B pots are used as the individual pickup volume controls. Swap the A's and B's around if you think you'll be using the pickup volumes more than the master. The two 0.047uF caps are wired in series on the tone control, which gives you a nett 0.0235uF value. If you want the darker 047 tone just use a single cap. The tone is wired on the output of the master volume, as per the original schematics, but this can make them a little intertwined (volume affects tone, tone affects volume) so be warned.

If the tone/volume interaction is something you want to avoid, then 'modern' solution is to wire the tone to the 'in' lug of the master volume. This diagram does that, again with all stock parts, but has the added benefit that you can just connect the tone to the output of the pickup selector switch, no long wire run required.


Another traditional layout uses a tone switch with 0.0039uF and 0.012uF caps instead of a tone control. So, if you've got a couple of caps and either a DPDT or SPDT On/Off/On mini-switch laying around you can add this without having to drill any extra/larger holes in your kit.


The 0.0039uF cap setting will just drop off the upper highs, while the 0.012uF setting will give you a slightly darker tone (but still less than a standard tone control).

If you want to try a tone switch, you can actually do it will On/Off/On or On/On/On mini-switches, or even standard 3-way toggle switches:


With the mini-switches you can use whatever individual cap values you want, but it's not so straight forward with the 3-way toggles. With them you can't have one cap or the other, instead you can only have one or both. This works fine if you have one medium/large value cap and a comparatively small value one, like above, as the two are summed in the 'both' position (0.012 + 0.0039 = 0.0159uF) so there is little impact. But, if you have two medium/large values you need to take a different approach.

If you wanted to use a 3-way toggle to switch between say a 0.022uF and 0.047uF cap, you actually need to use two 047's and wire them this way:


In the 'both'/middle position it shorts one cap so you just get a single 0.047uF cap, while in the other position it gives both caps in series which gives you a value of 0.0235uF. If you used two 0.022uF caps you'd get a series value of 0.011uF. Not that you're likely to ever be doing this… so I don't know why I bothered

[WeirdBits]

Back on topic...

Note: All of the following diagrams are wired with tone connections on the 'in' lug of the volume pot (modern style), rather than on the 'out' lug of the traditional schematics (easy to change if needed).

If you're willing to add a few more extra parts you can combine a couple of the traditional schematics into some interesting designs. The Gentleman who lives in the Country style layout has a master tone and bridge volume, but if you add an On/On/On mini-switch you can also have tone switch options. A CG tone switch hybrid:



With the mini-switch up you get a normal tone control, but in the other two positions the tone control is disconnected and instead you get the tone switch caps. Even better with No Load tone pot.

If you replace the above's bridge volume with a balance pot you can adjust the balance/volume between the pickups and have the hybrid tone control/switch.


Turn the balance pot clockwise (towards the neck) to reduce bridge volume, turn it counter-clockwise (towards the bridge) to reduce neck volume. Same as the previous, with the mini-switch up you get the normal tone control, but in the other two positions the tone control is disconnected and instead you get the tone switch caps.

Finally, if you're willing to plug up the second hole on the upper bout you can go for a cleaner look with just a master volume, balance, master tone and the 3-way toggle.


As usual, use at your own risk.

[Gavin1393]

As always a brilliant read with so many options!

[dingobass]

Once again, Weirdy comes up with some brilliant wireing scematics

[Jeff Sheridan]

Thanks WierdBits great diagrams, made wiring my Grs-1sf a lot easier! I used the last diagram and it's working great, I love being able to turn one pickup all the way off so I can use the toggle as a kill switch. Plus the guitar looks cleaner with a few less buttons

[Rodger]

Hello Jeff, I’m thinking of using the same wiring option on my build also. It is accurate to assume the following-

- The balance pot works like a volume when the switch is set to either the bridge or neck exclusively; and
- The balance pot works as a pure balance when the switch is set to the middle position i.e. neck and bridge.

Also, how did you go about plugging the extra switch hole?

And a big thanks to WeirdBits for the brilliant guides.

Regards

Rodger

[WeirdBits]

Hi Rodger, that diagram is set up as: pickups -> balance pot -> toggle switch -> master volume. The balance pot is always in the circuit so its setting also affects the relevant pickup when selected individually. The toggle switch just selects which half of the balance pot (bridge/both/neck) is connected to the master volume.

With the balance at the centre detent both pickups are at 100%, so bridge or neck will be at 100% volume when selected individually. Turning the balance counter-clockwise from centre keeps the bridge at 100% and reduces the neck volume, turning it clockwise from centre keeps the neck at 100% and reduces the bridge volume. So, if you have the balance set at 50% bridge/100% neck then with the toggle switch in the bridge position you'll get 50% bridge volume, in the neck position you get 100% neck volume, and in the middle position you'll get 50% bridge and 100% neck.

You need a multi-pole toggle switch if you want to do something more complicated, like remove the balance pot from the circuit when an individual pickup is selected leaving you just the master volume control.

How you plug the hole will depend on the type of finish you want to use, stain or solid colour etc.

[Rodger]

Scott, thanks very much for the explanation mate and the effort you have put into the reply. For the first time ever I think I actually understand everything you said. This ain't no small miracle I can assure you. I think I like the sounds of this setup as I guess you still have the master volume to adjust everything and have rolling adjustment between the tones of the bridge and neck pickup when switched to middle position. I also would like to get rid of the extra switch on the upper horn.

You're right about plugging the switch hole. I think I'm going to go solid colour with a nitrocellulose paint finish at this stage unless someone convinces me otherwise. I explored the forum a bit more today and saw a photo of the hardwood plug Jeff used on his excellent build. I'll do the same.

I don't want to push the friendship but I was wondering if you had any idea on the following. I have an Epiphone Riviera which I retro fitted a bridge humbucker and neck p90 single coil. The set up includes a 3 way switch and 2 tone 2 volume. The problem I got with the wiring job is that in bridge or neck switch position, the volume is never right off until both volumes are at 0. Any idea on what I've done wrong?

Rodger

[WeirdBits]

Start a new thread for your Riviera and we'll work through it there.

[WeirdBits]

A forum member asked about a custom GR-1SF layout based on the balance pot & tone switch diagram, but with the added option of coil splits on the pickups. The stock hole layout was to be maintained, so push/pulls are the easiest solution. One push/pull would allow both pickups to be split at the same time, and two push/pulls would allow them to be split individually. However, in each case it would be splitting to a fixed coil. By inter-linking two push/pulls you lose the option of individual splits but gain the ability to split to either coil and have the humbuckers as series coils (standard) or parallel coils.

As Tonerider pickups are being considered for the build I've used Tonerider colours in the diagram. They use red (hot) and black for the slug/north coil, white and green (ground) for the screw/south coil and have a bare shield wire (if using another brand of pickups you'll need to determine which colour pairs they use for each coil etc.). The coils are ordered as the screw coil first (with the ground connection) which links to the slug coil second which has the hot/output. A standard split on Tonerider humbuckers would give you a pair of slug/north coils when the pickup selector is in the middle position, which isn't hum-cancelling. So, on the diagram I've re-ordered the neck pickup's coils so that when split and in the middle position you always have a hum-cancelling slug/screw pair, either slug bridge and screw neck or screw bridge and slug neck. The trade off is you can get either coil on each pickup, but never the same coil on both pickups at once. Given the lack of shielding in a hollow body and the potential for noise, I think hum-cancelling splits are the better choice.

The diagram isn't as complicated as it looks:


The push/pull options are as follows:

MV = Master Volume, MT = Master Tone, up = Push/Pull up, down = Push/Pull down
(Setting affects both pickups)

MV down, MT down: Series coil humbuckers (default)
MV up, MT down: Bridge slug coil, Neck screw coil
MV down, MT up: Bridge screw coil, Neck slug coil
MV up, MT up: Parallel coil humbuckers

You will typically want the bridge pickup split to its slug coil, so I've configured the layout so the default split when you pull the Master Volume up is bridge slug coil and neck screw coil.

In the diagram, the left side lugs on the push/pull switches are the bridge pickup's connections, and the right side lugs are the neck pickup's. If you look at the Master Tone's push/pull lugs, the left side has the bridge pup's red at the top (slug hot) and white in the middle (screw hot) which is the standard order for the coils, green then goes to ground and black to the Master Volume push/pull. The right side of the Master Tone's push/pull has the neck pup's white at the top (screw hot) and red in the middle (slug hot) which is the swapped coil order, the black then goes to ground and the green to the Master Volume push/pull. Basically, this connects the bridge pup as screw->slug order and the neck pup and slug->screw order, which allows the hum-cancelling splits.

The tone switch trims off the highs depending on the cap values, but it is a bit of an all or nothing item. In the first position you get your normal tone control, but in the other two positions the tone pot is disconnected and you just have the treble cut caps. If you have caps that match your sound and the tones you want and/or that suit the guitar and pups etc, great. However, if the caps don't suit, it'll never get used and is just a waste. The 0.0033 and 0.01 caps listed on the diagram are just a starting point, as they're similar to the original tone switch values... but definitely experiment before committing. I'd probably also try an 0.0022uF and 0.0068uF pair or similar values, given the likely warmth of the large hollow body.

The layout above shows what to connect to where, but not how you should make those connections. Given the difficulty in wiring or, worse, re-wiring a hollow body I would probably use 4 core shielded audio cable to wire this layout. Run single core shielded cable from the output jack to the master volume, and another length of shielded single core from the master volume to the pickup selector toggle. That gives you your 'hot' from the jack to the volume out and from the volume in to the toggle switch and the shield can carry the jack's ground to the volume and on to the toggle switch. Then, use the shielded 4 core to run between the volume and tone push/pulls. The cores carry the yellow and pink switch links and the green and black pickup wires, and the shield links the ground from the volume to the tone. I'd also use the 4 core shielded to run from the tone and balance pots to the pickup selector and tone switch, with 3 of the cores carrying the orange tone connection to the tone switch and the light blue and purple outs from the balance pot to the selector switch. Then run a ground link from the tone to the balance etc.

To make it even easier I'd probably use some Veroboard or similar as a pickup link so I could connect two lengths of the 4 core shielded cable to the loom as if they were the pickup leads, and then connect the pickup leads to the Veroboard (see below). The board could be insulated and then double-sided taped or cable tied to the underside of the pickup. Then, if you ever needed to, you could swap the pickups without having to remove the loom. As an added bonus, you could even swap the coil order via the Veroboard, rather than in the actual loom, and wire the right side lugs of the push/pulls the same as the left side lugs above. On the Veroboard you would just connect neck pickup red to loom lead white etc, and the coil order is swapped. Like so:


The image on the left links the pickups directly to the loom leads and matches my wiring diagram where the neck pup's coil order is swapped in the loom. The right image is where you wire the loom symmetrically with both pickup's connections the same and swap the neck's coil order by cross-connecting the pup leads on the Veroboard instead (not confusing at all). You could even put the tone switch caps on the Veroboard for easy access, and just run wire links from there to the tone switch.

Anyway, enough prattling, it's another option for the GR-1SF. Questions, comments or derision at your convenience.

As always, use at your own risk.