Changing Resonant Frequency instead of Changing Pickups

State of Epicicity

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EDIT: Read post 57

This has changed everything for me.

I've been intrigued by the idea of integrating trimpots to my guitar to fine tune my pickups' response. Wiring a resistor to the outer lugs of your volume pot will lower the resonant frequency, essentially changing the fundamental tone of your pickup, as if you had just swapped your pickup for another one entirely; yes, it's the same construction, magnet, wire, and design, but it's a drastic change.

So I thought, rather than a fixed resistor that you'd have to swap out just to try a different value, couldn't you just use a variable resistor, a pot, to get it just where you wanted? And that's what a trimpot is, a tiny, easily installable variable resistor. So tonight I wired in a 500k trimpot to the outer lugs of the volume pot of each pickup (connecting lug 3 of the volume pot to lug 3 of the trimpot, and lug 1 of the volume pot to lug 2 of the trimpot), with long wires so they'd dangle from the pickguard.

As I was playing, I just adjusted the trimpots until the pickups were "tuned" perfectly to the guitar. I could hear the pick attack change as I was doing it, with volume and tone pots on 10, and you could just feel in the guitar go in and out of a sweet spot for each pickup.

This is my Sun Valley Super Shredder Black Limba that I'm doing this on, a very very bright guitar, and I had just reinstalled my favorite pickups, the Duncan Saturday Night Specials, which are also bright. Why do that? To me these pickups are just very nuanced and expressive, just what I want; the only caveat is that they're really designed for Les Pauls, which are so much darker than my guitar.

So tonight I installed an A500k / A500k dual concentric for volume and tone on the neck, and an A250K / A250K dual concentric for the bridge. With the trimpots, the guitar went from unbearably bright to perfectly balanced. I wanted my superstrat basically to sound like the most ideal Les Paul, and to my ears, this completely did it. I used 50s wiring for each pickup, with a 3-way blade switch pickup selector, with a .015 cap for the neck tone and .010 on the bridge. Now it's versatile, beautiful sounding, and tonally balanced. Now that I've fine tuned the pickups, I'll install the trimpots under the pickguard tomorrow.

Pure joy!
 
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I think you're tuning your pickup resonance to your rig as a whole (including it's current settings and your listening position in space) and not tuning to your guitar as you say.

but hey glad it worked it for you!

sounds like a great idea to add trim pots to adjust frequency response

though I would like someone with knowledge on this to make sure adding a variable potentiometer / trimpot , does shifts the resonant frequency response of a pickup
 
This has changed everything for me.

I've been intrigued by the idea of integrating trimpots to my guitar to fine tune my pickups' response. Wiring a resistor to the outer lugs of your volume pot will lower the resonant frequency, essentially changing the fundamental tone is your pickup, as if you had just swapped your pickup for another one entirely; yes, it's the same construction, magnet, wire, and design, but it's a drastic change.

So I thought, rather than a fixed resistor that you'd have to swap out just to try a different value, couldn't you just use a variable resistor, a pot, to get it just where you wanted? And that's what a trimpot is, a tiny, easily installable variable resistor. So tonight I wired in a 500k trimpot to the outer lugs of the volume pot of each pickup (connecting lug 3 of the volume pot to lug 3 of the trimpot, and lug 1 of the volume pot to lug 2 of the trimpot), with long wires so they'd dangle from the pickguard.

As I was playing, I just adjusted the trimpots until the pickups were "tuned" perfectly to the guitar. I could hear the pick attack change as I was doing it, with volume and tone pots on 10, and you could just feel in the guitar go in and out of a sweet spot for each pickup.

This is my Sun Valley Super Shredder Black Limba that I'm doing this on, a very very bright guitar, and I had just reinstalled my favorite pickups, the Duncan Saturday Night Specials, which are also bright. Why do that? To me these pickups are just very nuanced and expressive, just what I want; the only caveat is that they're really designed for Les Pauls, which are so much darker than my guitar.

So tonight I installed an A500k / A500k dual concentric for volume and tone on the neck, and an A250K / A250K dual concentric for the bridge. With the trimpots, the guitar went from unbearably bright to perfectly balanced. I wanted my superstar basically to sound like the most ideal Les Paul, and to my ears, this completely did it. I used 50s wiring for each pickup, with a 3-way blade switch pickup selector, with a .015 cap for the neck tone and .010 on the bridge. Now it's versatile, beautiful sounding, and tonally balanced. Now that I've fine tuned the pickups, I'll install the trimpots under the pickguard tomorrow.

Pure joy!
This sounds pretty interesting!
Question: Couldn't you measure the resistance of the trim pot when you hit the sweet spot, and just install a fixed resistor of that value?
 
I think you're tuning your pickup resonance to your rig as a whole (including it's current settings and your listening position in space) and not tuning to your guitar as you say.

I've found over the past many years that, no matter the IR, amp, and / or drive combination, I like the tone of my guitar better with the volume and tone knobs rolled back to a certain level. The pick attack is what gives it away. The fundamental character of the guitar is always a little too bright to my ears. I guess this is because the best sounding guitar I ever had was a Washburn P3, which essentially was a modern take on a Les Paul, and next to that for tone and mojo was my Epiphone Les Paul. Eventually I felt like my fretting hand wrist was breaking from the chunky Les Paul neck heel, so I went searching for superstrats with good upper fret access, but in the back of head I nonsensically want them to sound like a Les Paul.

And although I would like to keep my volume and tone knobs rolled back for each pickup, I still ride them to different positions all the time. So I realized I was missing that last little bit of potential in the knobs. This way I can have them at full and not even have to waste the time getting rid of a pick attack that's too much for this guitar.

I worded it as tuning the pickups to the guitar because I hear it in every type of tone the same way. It's just undeniably the guitar itself that just inherently needs sweetening to my ears. When I did my sweetening with the trimpots last night, I used the Dumble ODS Clean, the 50W Plexi 6CA7, and the block letter 5150 Lead, and they all were calling for the same trimpot settings, to my ears.

If I thought of it the way you're saying that I'm tuning to the rig of the moment, I'd just have kept the knobs as the were, honestly, because I adjust my knobs to the amp tone anyway as part of the process. But what made me think to install a resistor whose value never changes is the fact that, whenever I would go to the highest level that sounded good to me with my knobs, it was always the same level.

I actually considered trying to find a good way to mount the trimpots to the pickguard for constant access, but I just know the ideal setting of my volume and tone knobs never changed for me. Now, since this is largely based on pick attack, if I change to a new type of pick that's a different story, and I'd want to retune the trimpots then.
 
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This sounds pretty interesting!
Question: Couldn't you measure the resistance of the trim pot when you hit the sweet spot, and just install a fixed resistor of that value?

Yes, totally! As long as a fixed resistor of that exact size exists, or (I think) if you can create a resistor / capacitor combination that equals that. But why go to all that trouble when this 3mm unobtrusive little thing already has the exact perfect value you've tuned by ear?

In many online examples, to illustrate what I'm thinking, people talk about making a 500k pot load your pickup like a 250k pot. So the formula dictates you need a 500k resistor across the outer lugs to do that, but no 500k fixed resistors exist. So instead, people use a 470k, which is readily available. That's totally fine. But then add the complication of pot tolerances: your pot is not 500k to start with; it's within 20% of that value, which is a huge range. So now you're measuring the real world resistance if your pot, measuring the seeing you like of the trimpot, running your calculations, searching for the right fixed resistor, etc...

Also, the form factor. I bought a pack of twenty-five trimpots designed to be installed to breadboards, for $7.00 or so, if I recall correctly. And these things actually take up less space than a fixed resistor! Yes, you do have consider the wires to and from the trimpot, but the body of it is still shorter than that of a fixed resistor. I can't think of any advantage in this context of a fixed over a variable resistor.

The other thing is, I'm a total layman about electronics, and I'm barely hanging on with what I understand, just what I've gleaned from forums and random online articles, enough to get around my passive wiring with a soldering station. And I'm trying to keep it as quick and simple as possible, and to use my ears for all of it. Nothing's simpler to me than just turning a knob until it sounds good.
 
To add to this, it is possible to do the reverse, to make your pickup's resonant frequency rise with a capacitor. I don't know the details, and I don't think small variable caps exist, so then you do probably want to find a value that brightens a little too much, then use a trimpot then to lower to three perfect spot from there.

The Bing AI chatbot is actually a good starting place for specific guidance on this stuff too, I've found. It will point to you to its references.
 
Yes, totally! As long as a fixed resistor of that exact size exists, or (I think) if you can create a resistor / capacitor combination that equals that. But why go to all that trouble when this 3mm unobtrusive little thing already has the exact perfect value you've tuned by ear?

In many online examples, to illustrate what I'm thinking, people talk about making a 500k pot load your pickup like a 250k pot. So the formula dictates you need a 500k resistor across the outer lugs to do that, but no 500k fixed resistors exist. So instead, people use a 470k, which is readily available. That's totally fine. But then add the complication of pot tolerances: your pot is not 500k to start with; it's within 20% of that value, which is a huge range. So now you're measuring the real world resistance if your pot, measuring the seeing you like of the trimpot, running your calculations, searching for the right fixed resistor, etc...

Also, the form factor. I bought a pack of twenty-five trimpots designed to be installed to breadboards, for $7.00 or so, if I recall correctly. And these things actually take up less space than a fixed resistor! Yes, you do have consider the wires to and from the trimpot, but the body of it is still shorter than that of a fixed resistor. I can't think of any advantage in this context of a fixed over a variable resistor.

The other thing is, I'm a total layman about electronics, and I'm barely hanging on with what I understand, just what I've gleaned from forums and random online articles, enough to get around my passive wiring with a soldering station. And I'm trying to keep it as quick and simple as possible, and to use my ears for all of it. Nothing's simpler to me than just turning a knob until it sounds good.
Now I get it....for some reason I thought you were going to try and mount them so you could always adjust them......don't ask me where I got that from cuckoo.gif. Anyway, yes, considering they're so small, I guess you could leave them there. I would, however, shorten the wires before buttoning

it up, you know, just to tidy things up.
 
I am wondering if there would be any difference between that, or adding a surgical PEQ at the beginning of the Axe-FX chain. I use a PEQ very often to reshape the nuances of my pickups.

I also use a Pitch Follower Modifier to emphasize a frequency around 450HZ only when playing the higher notes. It avoids a thin sound when reaching the first string above the 12th fret
1678625950142.png
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I am wondering if there would be any difference between that, or adding a surgical PEQ at the beginning of the Axe-FX chain. I use a PEQ very often to reshape the nuances of my pickups.

I also use a Pitch Follower Modifier to emphasize a frequency around 450HZ only when playing the higher notes. It avoids a thin sound when reaching the first string above the 12th fret
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This will work but not everyone is familiar with frequencies by number. It's good to take time to cut and boost across the range to teach your self the sound. It make programming patches soo much easier if you get familiar with the sounds of parameters and what you need to do to get the results you'r looking for quickly.
 
I am wondering if there would be any difference between that, or adding a surgical PEQ at the beginning of the Axe-FX chain. I use a PEQ very often to reshape the nuances of my pickups.

I also use a Pitch Follower Modifier to emphasize a frequency around 450HZ only when playing the higher notes. It avoids a thin sound when reaching the first string above the 12th fret
View attachment 117558
View attachment 117559

Yeah, that's a great idea, but it's not the same. I had posted a thread asking if I could recreate my tone and volume knobs on the Axe-FX III, but Cliff wrote that you cannot recreate the pots' load on the pickups. You can roughly approximate with PEQ, but nowhere near as powerful as actually lowering your resonant frequency.

Here's the other factor: I find sweet spots that were different for each pickup! So for me, I'd end up with a different PEQ to activate whenever I touch my pickup selector!

And what I did costs so little, and takes very little soldering.
 
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Interesting I've never tried this or even seen it done.

That's awesome to hear coming from you! I found many threads on various forms talking about using fixed resistors this way. The most in depth was in the Guitar Nuts 2 forum, where the moderator Antigua had charts and graphs illustrating the effects with fixed resistors and caps. But I found a random suggestion in a thread on some site, probably TGP, for someone to pad a pickup to balance HSS output with a full size pot in their guitar cavity. I thought, shit, why use a full size pot when trimpots exist?
 
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I am wondering if there would be any difference between that, or adding a surgical PEQ at the beginning of the Axe-FX chain. I use a PEQ very often to reshape the nuances of my pickups.

I also use a Pitch Follower Modifier to emphasize a frequency around 450HZ only when playing the higher notes. It avoids a thin sound when reaching the first string above the 12th fret
View attachment 117558
View attachment 117559

Additionally, PEQ won't quite do it either. I learned from a user on that thread that a tone pot is a first order low pass filter, and that only exists in the Axe-FX III at this point in the Filter block. I experimented and got great results, but it still was not nearly as good as actually changing the fundamental, the resonant frequency.
 
Here's what it looks like right now, with the trimpots dangling:

2A6AB15A-3E26-4614-9D1C-DBAFC421BC6E.jpeg

And I'll just use short shielded hookup wires later today when I finish shoveling snow to move them under the pickguard. You can see where I didn't feel the need to keep any more mini switches in my guitar, so I covered them with copper foil, which I'll then cover with Sugru, like I did in the red areas.
 
Additionally, PEQ won't quite do it either. I learned from a user on that thread that a tone pot is a first order low pass filter, and that only exists in the Axe-FX III at this point in the Filter block. I experimented and got great results, but it still was not nearly as good as actually changing the fundamental, the resonant frequency.
Of course! That's right. I have to try the Filter instead of the PEQ, and experiment with the notch of the Highpass when the Q is higher than 1
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Wow, this is a crazy neat idea. Can't wait to hear/see more!
I really like the idea of the small trim pots. You can always make an adjustment if needed.
 
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