Really "in the weeds" question about wiring

[GeekyToneChaser]

I have a two p90 pickup (LP style) guitar with a 3-way switch.

LOVE the neck p/u sound by itself - no changes. Volume = 8, Tone = 8, with great options along the 'sweep' of the pot, assuming you know what I mean. It's in the zone.

I also get an AMAZING middle sound, set with mostly the neck p/u, and a little contribution from the bridge p/u blended in. Like, neck vol = 8, neck tone = 8, bridge vol =4 , bridge tone = 2.

The trouble, is that when I click over to the treble/bridge pickup 100%, now the volume is on 4 and the tone is on 2 - just to get in the neighborhood of usable - but if I'm being honest, the bridge p/u just sucks. Way too bright and what I would like is a chance to use the bridge p/u for cutting through for solos / key parts, etc.

But, if I play with it, and get the vol/tone settings right for the bridge p/u alone, the results are good... but the middle position loses the magic.

I need help figuring out how to use the bridge p/u as a "contributor" to middle position tone, while perhaps providing separate "settings" for "bridge only" hotness.

Thoughts I have had include oddball wiring, pot value changes, tone cap changes. Nothing is off the table. HELP!

 

[eallen]

First stop if you haven't already is pickup height adjustment to get the pickups balanced between each other as you like. Raise the bridge or drop the neck to get equal volume at the same control positon. Drop the treble side to reduce highs.

If you can't get the highs cut as you like you can start looking at adding a 200k resistor from the bridge pup lead off the switch to ground in parallel. It will roughly cut a 250k pot value in half of when using the bridge thus reducing highs. Bill Lawrence had a good simple drawing of doing so.

 

[Peegoo]

@GeekyToneChaser If the bridge pickup is overly bright, the pickups may be imbalanced. If both pickups are supposed to be a matched set from the same maker, here's an super easy way to determine this.

Set all the guitar's controls on 10 and plug a short cable into the guitar's jack. Set your meter to read DC Ohms and connect the test leads to the end of the cable; polarity does not matter.

Flip the switch to the neck pickup position and take note of the reading. Most P90s read in the neighborhood of 8k Ohms (8 kiloOhms, or 8,000 Ohms). Flip the switch to the bridge position and note the reading. It should be nearly the same; around 8k Ohms.

But the bridge pickup should read a little more than the neck pickup. For example, if the neck pickup reads 8k Ohms, the bridge pickup should be close to 8.2k Ohms or so. Generally, pickups sound balanced when the bridge reads about 200 Ohms more than the neck pickup. If the bridge pickup reads 300 Ohms or more than the neck pickup, that may be why the bridge pickup sounds overly bright.

Another reason may be the pickups' magnets are imbalanced (bridge has a stronger set of mags than the neck pickup).

 

[generic202]

Let me suggest a different solution.

What I'm reading is that you already have good sounds in all positions, but in order to get there, you have to adjust your bridge pickup's vol&tone controls between middle and bridge positions.

This can be solved by adding a second set of pre-dialed vol/tone settings for bridge pickup and using a push/pull (or a separate DPDT switch) to switch between pre-dialed settings or knob settings. I mean you suggested this yourself:

I need help figuring out how to use the bridge p/u as a "contributor" to middle position tone, while perhaps providing separate "settings" for "bridge only" hotness.

You can use mini trim-pots (or resistors) to create fixed vol/tone settings and put them inside the cavity. So for example, you can pre-dial your favorite vol=4 & tone=2 setting one side of the switch and the other side of the switch would be your regular vol&tone knobs which can be dialed for optimized bridge-alone tone. This way, it would be just a flick of a switch to change between two different bridge settings. I hope this makes sense.

 

[Deaf Eddie]

Why not put the bridge pickup on a p/p "blow" switch - wired to bypass its volume pot when pulled. Set the bridge volume so that you like the blend, and then when you want to use the bridge pickup alone, pull the p/p.

 

[eclecticsynergy]

Why not put the bridge pickup on a p/p "blow" switch - wired to bypass its volume pot when pulled. Set the bridge volume so that you like the blend, and then when you want to use the bridge pickup alone, pull the p/p.

You can easily include a separate tone control for the 'blower' position, a simple trimpot & cap using the other half of the push-pull. Dial the trimmer to taste and close up the control compartment; you can always redial it in the future if you want.

 

[GeekyToneChaser]

Let me suggest a different solution.

What I'm reading is that you already have good sounds in all positions, but in order to get there, you have to adjust your bridge pickup's vol&tone controls between middle and bridge positions.

This can be solved by adding a second set of pre-dialed vol/tone settings for bridge pickup and using a push/pull (or a separate DPDT switch) to switch between pre-dialed settings or knob settings. I mean you suggested this yourself:



You can use mini trim-pots (or resistors) to create fixed vol/tone settings and put them inside the cavity. So for example, you can pre-dial your favorite vol=4 & tone=2 setting one side of the switch and the other side of the switch would be your regular vol&tone knobs which can be dialed for optimized bridge-alone tone. This way, it would be just a flick of a switch to change between two different bridge settings. I hope this makes sense.

Mini trim pots inside the cavity sounds like an ideal solution.

The guitar has a LP style 3 way switch and 4 knob setup.

So, for the 3-way switch:
* Treble = bridge p/u --> mini trim 1 (vol) --> mini trim 2 --> output
* Middle = standard wiring, with the 4 external pots
* Rhythm = standard wiring, with the 4 pots

How would this be achieved? I can wire things up from a diagram, but I'm not confident in my ability to create a wiring diagram from scratch with proper grounding.

 

[GeekyToneChaser]

Why not put the bridge pickup on a p/p "blow" switch - wired to bypass its volume pot when pulled. Set the bridge volume so that you like the blend, and then when you want to use the bridge pickup alone, pull the p/p.

I like this idea too - and found a blog on Seymour Duncan describing what a p/p blower switch is for anyone reading and wondering:

Adding a Blower Switch to Your Guitar: Guitar Wiring Explored

Adding a blower switch is great for switching between rhythm and lead tones instantly. Check out this article to learn how to install one.

www.seymourduncan.com

Sounds like I have 2+ really good suggestions to pursue. Thanks everyone!

 

[schmee]

"The trouble, is that when I click over to the treble/bridge pickup 100%, ......- but if I'm being honest, the bridge p/u just sucks. "
I find this with most guitars, not just P90's.
But If the P90 is too bright, consider lowering it. I like P90 types lower than any other pickup type.

The other consideration is wiring and tone/volume pot choices that give you a better "tone sweep". Many just jump from bright to warm way too fast instead of spreading it across the dial...

 

[fenderchamp]

"The trouble ... the dial...

 

[GeekyToneChaser]

@GeekyToneChaser If the bridge pickup is overly bright, the pickups may be imbalanced. If both pickups are supposed to be a matched set from the same maker, here's an super easy way to determine this.

Set all the guitar's controls on 10 and plug a short cable into the guitar's jack. Set your meter to read DC Ohms and connect the test leads to the end of the cable; polarity does not matter.

Flip the switch to the neck pickup position and take note of the reading. Most P90s read in the neighborhood of 8k Ohms (8 kiloOhms, or 8,000 Ohms). Flip the switch to the bridge position and note the reading. It should be nearly the same; around 8k Ohms.

But the bridge pickup should read a little more than the neck pickup. For example, if the neck pickup reads 8k Ohms, the bridge pickup should be close to 8.2k Ohms or so. Generally, pickups sound balanced when the bridge reads about 200 Ohms more than the neck pickup. If the bridge pickup reads 300 Ohms or more than the neck pickup, that may be why the bridge pickup sounds overly bright.

Another reason may be the pickups' magnets are imbalanced (bridge has a stronger set of mags than the neck pickup).

Neck = 7.7
Bridge = 8.3

 

[Peegoo]

Are they by the same maker? If so, they should be good.

 

[redhouse_ca]

I have a two p90 pickup (LP style) guitar with a 3-way switch.

LOVE the neck p/u sound by itself - no changes. Volume = 8, Tone = 8, with great options along the 'sweep' of the pot, assuming you know what I mean. It's in the zone.

I also get an AMAZING middle sound, set with mostly the neck p/u, and a little contribution from the bridge p/u blended in. Like, neck vol = 8, neck tone = 8, bridge vol =4 , bridge tone = 2.

The trouble, is that when I click over to the treble/bridge pickup 100%, now the volume is on 4 and the tone is on 2 - just to get in the neighborhood of usable - but if I'm being honest, the bridge p/u just sucks. Way too bright and what I would like is a chance to use the bridge p/u for cutting through for solos / key parts, etc.

But, if I play with it, and get the vol/tone settings right for the bridge p/u alone, the results are good... but the middle position loses the magic.

I need help figuring out how to use the bridge p/u as a "contributor" to middle position tone, while perhaps providing separate "settings" for "bridge only" hotness.

Thoughts I have had include oddball wiring, pot value changes, tone cap changes. Nothing is off the table. HELP!

Others have given great suggestions, but one other thing to consider is 50s style wiring. This would change everything about the way the tones are dialed in, and that may or may not be good, but the volume and tone work together differently with that wiring (which I learned here), and dialing up the tone dials up the volume, vs jist limiting more and more of the frequency spectrum as you dial up the tone (it does that, but does so while increasing volume, at least with the wiring I have).

Note: "50s" style may not be a perfect description for what I mean, but I can send wiring if you wanna mess around with that. Again, its gonna change everything about the times/settings you got now, but who knows, maybe it solves this issue or gives you something better .

 

[GeekyToneChaser]

Are they by the same maker? If so, they should be good.

Yes, both by same maker. And supposedly a matched set, but I won't provide the details to protect the innocent.

 

[GeekyToneChaser]

First stop if you haven't already is pickup height adjustment to get the pickups balanced between each other as you like. Raise the bridge or drop the neck to get equal volume at the same control positon. Drop the treble side to reduce highs.

If you can't get the highs cut as you like you can start looking at adding a 200k resistor from the bridge pup lead off the switch to ground in parallel. It will roughly cut a 250k pot value in half of when using the bridge thus reducing highs. Bill Lawrence had a good simple drawing of doing so.

View attachment 1095658

Question, since I'm not great with wiring diagrams. Will this modification (adding 200k resistor in parallel to the bridge p/u lead) impact just the bridge position? Or will it impact the center position too?

 

[MidwestLuthier]

Question, since I'm not great with wiring diagrams. Will this modification (adding 200k resistor in parallel to the bridge p/u lead) impact just the bridge position? Or will it impact the center position too?

Sorry if this is a little too late, but I see no one answered.

It will impact both, mainly just the bridge though. In your situation it may help because now you can have your bridge on 6 or 7, instead of 4 to get that magical middle tone.

 

[GeekyToneChaser]

Sorry if this is a little too late, but I see no one answered.

It will impact both, mainly just the bridge though. In your situation it may help because now you can have your bridge on 6 or 7, instead of 4 to get that magical middle tone.

Thanks! I have tried p/u height adjustment and also changed the tone cap from 22 - 46 with no major improvement. The pickups are simply imbalanced. Still, if that is the root cause, then putting a resistor on the bridge p/u may be the correct approach. I ordered this part from StewMac. Hopefully this will do the trick.

Resistors - StewMac

These are the same high quality resistors used by JHS Pedals and other leading makers of fine electronics.

www.stewmac.com

 

[pedro58]

I have found the same problem on 2-pickup Gibson-style guitars, both with humbuckers and P90's. What worked for me is a bass cut on the neck pickup's tone knob. Traditionally, the tone knob cuts high end, and few guitar players cut highs from a neck pickup on a humbucker or P90. With a bass cut, like one detailed here, you can make the neck position a bit brighter. This nudges things toward the mids, and then you don't have to pull so much treble from the bridge pickup to make it usable. Anyway, it's a simple to wire option that I've used and kept on two guitars now.