Using a linear pot for blend - help!

ThePrettyDamned

Okay, I'm sure someone (@ICBM?) posted how to do this, but I can't find it!

So I have a 500k volume, 500k tone (both log), a mini switch (which I'll use to coil tap the pickups - will look at the duncan wiring site to see how that's done but convert to Gibson pickup wire colours) and a 500k linear pot, which should work as a blend.  

Can anyone knock me up a quick diagram showing how I'd wire the two pickups to it?  It's wire with 5 wires (as in 4 conductor, plus shield?) but the most important ones for this, I'm guessing, will be the hot (RED) and the shield (nekkid, ooer) while the GREEN and WHITE are used for the coil tap.  Not sure what the black does  

I wish I was more electronically schooled.  

Many thanks for any advice it's 2 humbuckers btw.  So it should go pickups -> 500k Linear (as blend) -> DPDT switch -> volume -> tone -> output. Or maybe I have the tone and volume the wrong way around, but they're already wired up - I just need to do the mini switch and the blendy pot. 

ICBM

The series blend is quite simple...

The hot of the first pickup goes to one end of the blend pot and from there to the volume pot.
The cold (but not shield) of the first pickup and the hot of the second pickup go to the middle of the blend pot.
The cold and shield of the second pickup (and the shield of the first pickup) go to the other end of the blend pot and then to ground.

Now it gets more complicated - the coil split connections go to the mini-switch and then to whichever end of the pickup turns off the coil you don't want.

But to know which wires are which, you need to know the manufacturer's colour coding, which varies - eg, Duncan is: black = hot, red & white = coil split, green = cold. (Bare is always shield.)

steamabacus

On my bass I used a dual-gang pot like one of these to blend the pickups. The centre detent is a useful marker to keep track of where it's set (assuming no numbers on the knob).

ThePrettyDamned

steamabacus said:

On my bass I used a dual-gang pot like one of these to blend the pickups. The centre detent is a useful marker to keep track of where it's set (assuming no numbers on the knob).

I had one of these and destroyed it.  Apparently, the more obscure stuff (like push pull, push push and blend pots) are less hardy than the boring counterparts, so I'll stick with the boring stuff for the sake of not pushing it through the back of the guitar and smashing it into two separate pots (not kidding!).  

ICBM said:

The series blend is quite simple...

The hot of the first pickup goes to one end of the blend pot and from there to the volume pot.
The cold (but not shield) of the first pickup and the hot of the second pickup go to the middle of the blend pot.
The cold and shield of the second pickup (and the shield of the first pickup) go to the other end of the blend pot and then to ground.

Now it gets more complicated - the coil split connections go to the mini-switch and then to whichever end of the pickup turns off the coil you don't want.

But to know which wires are which, you need to know the manufacturer's colour coding, which varies - eg, Duncan is: black = hot, red & white = coil split, green = cold. (Bare is always shield.)

It's Gibson pickup coded what is the cold? According to Gibson, green and white is for coil split.

ThePrettyDamned

Also, @ICBM, when you say...

Now it gets more complicated - the coil split connections go to the mini-switch and then to whichever end of the pickup turns off the coil you don't want.

What do you mean?  I thought the coil tap connections (green and white) go to the mini switch, then go to ground (as per this diagram, tthough this uses a push/pull, the switch is basically the same).

http://www.seymourduncan.com/images/support/schematics/2h_1v_1t_3w_1pp.jpg

ICBM

If it's Gibson wiring, black is cold and red is hot - although as long as you're consistent with both pickups either way will do.

You can't send the coil splits to ground on both pickups - the 'first' pickup in the description above is not grounded, so its coil split needs to go to its cold connection and not to ground. The 'second' one can go to ground, but only because that is *also* the cold connection. If that gives you the wrong coils - with actual Gibson pickups it will, the 'slug' coil is the hot end - you need to switch it to the hot connection for each pickup instead.

ThePrettyDamned

ICBM said:

If it's Gibson wiring, black is cold and red is hot - although as long as you're consistent with both pickups either way will do.

You can't send the coil splits to ground on both pickups - the 'first' pickup in the description above is not grounded, so its coil split needs to go to its cold connection and not to ground. The 'second' one can go to ground, but only because that is *also* the cold connection. If that gives you the wrong coils - with actual Gibson pickups it will, the 'slug' coil is the hot end - you need to switch it to the hot connection for each pickup instead.

Oh gawd, here we go, I've gone cross-eyed. 

Okay, tell you what, is it okay if I draw a scheme, upload it and get feedback?  I'll use the proper gibson coding

Though might have to just label them...

ThePrettyDamned

Okay, here we go... It's NOT finished, obviously, but this is what I have so far.  The green represents both the green and the white wires, which are the split. 

<iframe src="https://www.flickr.com/photos/aguywitholdcameras/15439175302/player/" width="768" height="1024" frameborder="0" allowfullscreen webkitallowfullscreen mozallowfullscreen oallowfullscreen msallowfullscreen></iframe>

ThePrettyDamned

Balls, can't remember how to get flickr to work.

<a href="https://www.flickr.com/photos/aguywitholdcameras/15439175302" title="Untitled by Paul Allum, on Flickr"><img src="https://farm4.staticflickr.com/3927/15439175302_4f51d18264_b.jpg" width="768" height="1024" alt="Untitled"></a>

ThePrettyDamned

Hell yeah! NOW IT'S SIDEWAYS. 

Sorry, you'll have to live with it...

ICBM

lol

Yes, that all looks correct. Now all you have to do is connect the other mini-switch terminals to either the red or black wire from each pickup, depending on which coil you want to turn off. (Obviously make sure you connect each to the same pickup, not the other one!)

ThePrettyDamned

Okay, so... Tonal query would I rather keep the outer coils, or the inner ones do you think?

I'm thinking outer, which should give a roughly stratty location for the coils.  

In which case, red neck, black bridge... So... (beware, incoming picture!)

<a href="https://www.flickr.com/photos/aguywitholdcameras/15253004810" title="Untitled by Paul Allum, on Flickr"><img src="https://farm3.staticflickr.com/2942/15253004810_96c89edbfd_b.jpg" width="768" height="1024" alt="Untitled"></a>

ThePrettyDamned

FFFFFUUUUUUUUUUU Y B SIDEWAYS

ThePrettyDamned

Also, the blend pot isn't grounded to the rest of the circuit... It just connects to the volume pot via 1 wire, normally they're connected by a hot and a ground.  

Is this correct, or do I need to put a wire from the pot body to the volume pot body? Theoretically, it should be against the conductive paint anyway, but...

ICBM

The blend pot does need to be grounded, both the casing and one end terminal.

ThePrettyDamned

ICBM;369921" said:

The blend pot does need to be grounded, both the casing and one end terminal.

Cool, presumably the end with the shield.

Does the rest of the diagram look alright now? It's a wee bit more complex than I anticipated, but if that's it, it's doable - I have tomorrow off so I'll be experimenting and cooking solder all day!

ICBM

Yes, the end with the shield .

The only thing that might not work as you intended is that you have the coil splits operating on opposite coils of each pickup - but that has one advantage, which is that the mixed single coil sound is hum cancelling.

ThePrettyDamned

ICBM;369929" said:

Yes, the end with the shield .

The only thing that might not work as you intended is that you have the coil splits operating on opposite coils of each pickup - but that has one advantage, which is that the mixed single coil sound is hum cancelling.

Hum cancelling wasn't intentional, but opposite ends is - it should give me the outer coils of each, which should give me something slightly closer to a strat sound (I know it'll be nothing like that but one can try!).

Awesome, many thanks man. I'll click the wisdom button in the morning for you

ThePrettyDamned

Wired it all up, really ballsed it up (got some wires back to front) so rewired, then tested.

Nothing no buzz, no hum, no signal regardless of where the pots are set.

I'm going to see if I can buy a ready made Blend pot loom again. It was horrendous, working with the wiring in such a confined space.

If I can't get one, I'll have it wired as 2 volumes, a global tone and a coil tap. Might be a bit easier?

The ultra fine wires in 4 conductor wire really make it difficult to do

steamabacus

ThePrettyDamned said:

 It was horrendous, working with the wiring in such a confined space.

Can you make a card template for the pot positions? You could then do all the soldering outside the guitar and fit the completed loom in after.

Persevere - it's the only way to learn.

ThePrettyDamned

steamabacus;370407" said:

ThePrettyDamned said:

 It was horrendous, working with the wiring in such a confined space.












Can you make a card template for the pot positions? You could then do all the soldering outside the guitar and fit the completed loom in after.



Persevere - it's the only way to learn.

That is a damn good idea.

That is what I will do. I'll order a few new pots - but might give up on the blend pot.

The toughest bit is still the 4 conductor wiring though, which has to be done in-guitar.

So, should I go for volume - volume - tone and a coil tap, or should I go for the blend pot again?

Bah. I don't know where it's gone wrong, I'm assuming wires are damaged and the joints are bad. They don't look as pretty as normal...