Hum-P90-Hum?

[sumgai]

Dec 23, 2010 1:56:39 GMT -5 bigcookie said:

..... it's my project and I'll wire if I want to.

Ah, I see that Leslie Gore has struck again - trés cool! ;D



(Lest newey berate me once again for my forgetfulness.......)
bc,

Hi, and to the NutzHouse!




sumgaiu

[jcgss77]

bc,

You also asked which pots you should use. I would recommend using 250k pots, as it seems that guitar you are building seems to be bright, so 250k pots will help to darken the sound a bit.

250k are usually used with single coil guitars because single coils have a brighter sound already, so the 250k pot will balance that down a little.

500k are usually used with humbuckers as the humbucker has a darker sound. The 500k will bring that dark sound up a little bit.

[bigcookie]

Okay, here goes nothing. After way too much time spent contemplating multicolored spaghetti, I'm posting draft 1 below. I'm pretty sure that SOMETHING is right, but I'd be truly surprised if EVERYTHING was right. Mind you, this is my first time, so please be gentle.



Once again, the sequence is pup>vol>tone>SPDT>output jack. I made the white wires yellow so they're visible against the white background.

jcgss77 recommended 250k pots. As of now, I'm looking at 500k pots for the HBs and 250k for the P-90, although it seems like industry standard with P-90s is 500k. Anyone else want to chime in on this one? I'd also welcome thoughts on what kind of caps to use.

[cynical1]

Dec 25, 2010 1:58:08 GMT -5 bigcookie said:

Okay, here goes nothing. After way too much time spent contemplating multicolored spaghetti, I'm posting draft 1...

Well, kudos for gutting it out through the first draft. +1 for being Nutz enough to post it in the wee hours of Christmas.

Let me preface anything I say here with the fact that I'm not the first person you should go to for wiring help... There's a reason they put the soldering irons on the top shelf and lock me in the wood shop...

One thing ChrisK would always gig me for was my grounding schemes. To keep the tradition alive, this was the first thing I noticed here. Granted, with a completely hollow body a shielding routine is going to be tricky. That said, only one ground is necessary for your bridge ground.

I noticed you routed the black HB wires differently from each other. I also have a hard time following the signal path...but then, that's nothing new...

I can't see where the push\pull switches do anything in the signal chain. What is their designed function in the scheme?

The decision to use 500k or 250k pots has merits on both sides of the argument.

I would defer any additional comment until someone with a clue arrives and offers constructive insights. I would offer this drawing as a template to work from:



Granted, this has no bridge tone, and your design is a bit more involved, but the premise is similar.

And again, I commend your efforts in documenting a design and requesting assistance rather then just begging for a drawing. In the end you'll know it works and you'll have a design you understand.

Good start.

Happy Trails

Cynical One

[bigcookie]

Thanks for the praise. No this was not the most fun I've ever had, but I also feel that 'begging for a drawing' from folks here defeats much of the purpose of this thing. As for the hour at which I posted, I'm writing from Central Europe, so it might not have been as wee as you think.

Now to respond.

only one ground is necessary for your bridge ground.

Does this mean just 1 wire from 1 pot to bridge? The fewer wires the better.

Granted, with a completely hollow body a shielding routine is going to be tricky.

Yes, shielding is something I'm a bit concerned about, but I figure maybe the guys who sell the bodies have some suggestions on that.

I noticed you routed the black HB wires differently from each other.

I can't see where the push\pull switches do anything in the signal chain. What is their designed function in the scheme?

Here's the rub. The push/pulls are supposed to split the coils and I thought by routing the black wires from each HB differently I'd be splitting different coils (keeping the north coil from the neck HB and the south from the bridge HB). If I'm totally wrong on this, please let me know, I'm not easily offended.

I suppose I'm past the point of no return on this one, but very glad to be marching on with an army of GuitarNutz to help.

[cynical1]

Going along with ChrisK's "modular" approach to design, here's a few examples of what I think you're looking to do.





...or, since you're not doing series/parallel:



This last one can be handy as it allows you to choose the coils that reduce the hum with the P-90, as well as with the other humbuckers to make one "wide" humbucker. (IE: N neck and S bridge and visa versa) It will require an additional switch, as I don't know of any push\pull pots that do ON-OFF-ON.

Hope these help.

Happy Trails

Cynical One

[newey]

BC-

Your push/pulls are fine, they will do what you intend. Cyn is right that you don't need a DPDT switch to do so, but P/Ps only come with 2 poles.

You do need to decide which coils you want to split; ideallay, you would split the N coil on one and the S coil on the other so as to maintain humcancelling when both SCs were selected. To do so, you have to wire one of the HBs "inside out". Currently, you are splitting the N coils on both and shorting the S coils; this will not be humbucking if we assume both HBs are the same.

[JohnH]

Good work on the diagram - it will be just what you need , subject to a couple of things:

Tone pots - your top one is right, the other two need to be connected to the left volume pot lugs instead of volume pot grounds

You can simplify the grounding (although what you show will work):
Delete the black ground wires from switches to jack.
Delete all but one wire from pot backs to bridge ground
Delete wire from bridge ground to output jack.
Add a wire that jons all 6 pot backs together
Add a wire that goes from a pot back to the output jack

much less spagetti!

Note on p/p pots, there is usually a lug on the case at the back of he switch, which is an easy place to solder ground wires to.

I agree with newey on which coils to cut. On neck pup, swap green with white and red with black if you are concerned withh optimum humcancelling.

As shown, your switches will be on, with toggle lever up (interesting cultural difference: US convention is up=on, UK convention is down=on)

cheers

John

[bigcookie]

Wow, better results on draft 1 than I thought. I guess all that reading paid off.

Here's draft 2:



I tried to follow John's advice and cut down on the ground wires - I think it's okay now. Also made changes on the neck HB for the split. Please let me know if this is better.

[JohnH]

yep nearly - noticed a couple more things:
Your bridge vol and tone still needs fixing. Do it as the neck (except the wire colours not swapped)
On the P90, the red wire should go to vol pot left lug, the other wire goes to the pot case, and if there is a third wire, I assume that is for the case of the pickup, and that also goes to the pot case
Add a link between the pots, so that all 6 pot cases are connected together to ground
Its better on a diagram if lines for wires do not cross over lugs that they are not connected to

cheers

john

[bigcookie]

Your bridge vol and tone still needs fixing. Do it as the neck (except the wire colours not swapped)

Sorry, could you explain this in a bit more detail? What exactly do I have to move and where?

I'll redo the lines linking all the pots. Thanks again.

[newey]

Quote:
Your bridge vol and tone still needs fixing. Do it as the neck (except the wire colours not swapped)

Sorry, could you explain this in a bit more detail? What exactly do I have to move and where?

JohnH means that your Br volume pot should be wired exactly like the neck pot, except that the black wire goes to the left-hand lug instead of the red wire as on the neck pickup.

It looks like you show the left-hand lug on the Br V pot as being grounded to the pot's case; you want the right-hand lug grounded, not the left-hand one.

[JohnH]

What I mean is: on the bridge pup, the black wire from the pickup and the black wire from the tone pot should go to the left vol pot lug, which should not be grounded to the case. The right vol pot lug should be grounded to the case.

J

[bigcookie]

Gotcha now. Let's try this once again. I've tried to tidy it up a bit where possible. Could the 3rd time be the charm?



If this gets the thumbs up, the next (and final, for a while) question is about the caps. Given the nature of the build, what kind would you recommend?

[JohnH]

OK, that looks to be fully functional now. Just for the sake of neat wiring, the hot wire to the output jack, instead of connecting to the switch wires at a point in mid-air on the right, can go straight to the nearest switch Then just add two short lengths of wire from the B switch to the M switch, and one from the M switch to the N switch.

Now, are you interested in two entirely optional enhancements?
the first would be to add treble bleed components to each volume pot, comprising 1nF caps and 150k resistors in parallel between hot and centre lugs. Read all about it here:

guitarnuts2.proboards.com/index.cgi?board=wiring&action=display&thread=5317&page=1

posts 1 and 19 are the main bits.

Most guitars dont have this, but I would add them if it was mine, and the parts are less than a dollar total.


The second optional enhancement is to buy dpdt toggle switches (ie two-pole switches each with 6 lugs instead of single pole). The second pole can be used so that, if (and only if) all switches are off, the guitar output is shorted to ground. This is a really quiet all-off position, ideal for leaving your guitar during set breaks, without having to move pre-set volume knobs, or for high-gain staccatto effects. Without this, the all-off leaves the output floating and disconnected, which, depending on your set up, may allow a bit of buzz to be created through your amp. If you did this, it does not change your diagram so far. the extra connections, using the second poles would be to make a series chain from hot to ground through the 3 switches, broken if any pup is on.

I mention these things, without wishing to add complication, but in case you want to get the parts to add them, since its easier to get them in one go.

cheers

John

[bigcookie]

Thanks to all for checking my work and to John for the offer of the extra goodies.

As for the treble bleed, I think I'll pass, but I might be interested in the DPDTs over the SPDTs. I assume that I'd be looking at the on/on variety. Could you point me in the direction of a diagram for this? I'm a visual thinker and a novice to boot. Cheers.

[JohnH]

No problem, this is what I meant:



The left side of the switches is your wiring, with red from pickups and black arrow to output jack hot. The blue is the 'all-off' kill circuit, with the blue arrow going to ground at the back of a pot

cheers
John

[bigcookie]

Excellent John - eternally grateful.

And this'll work with on/on DPDTs?

[JohnH]

Dec 27, 2010 16:03:40 GMT -5 bigcookie said:

Excellent John - eternally grateful.

And this'll work with on/on DPDTs?

yes indeed - nothing special needed
J