Active mid-boost circuit for Mustang switch

[skern]

Hi guys. I'm planning on changing the electronics on my Squier VM Mustang. I want to have one 3-way switch behave like a normal 3-way pickup selector, and for the other 3-way, I want one of the positions to engage an active mid-boost. (The other two positions would be 1. normal and 2. I dunno yet, it doesn't matter.)

Can anyone provide some leads as to how I would do this without routing? I don't necessarily need to have an external knob to adjust the mid boost. I was thinking perhaps just an internal trimpot.

HOWEVER, if you think going without the external knob is asking for trouble, I could alternatively add a push-pull to the volume knob and replace one of the 3-way switches with one of those Jazzmaster roller pots that's connected to the mid boost circuit. Which begs the question, has anyone had any luck installing one of these roller pots in a stang without modification to the pickguard or cavity?

[alexpigment]

Seems like a roller pot+knob would fit vertically in the cavity, but you would need to cut the roller bracket down and drill a second screw hole to line up with the one already in the pickguard. Depending on how the roller lines up with the existing switch hole, you may need to drill two new holes in the bracket.

The real question in my mind is where you're going to fit the active boost board and battery without routing. Is that something you've already got figured out?

[skern]

Seems like a roller pot+knob would fit vertically in the cavity, but you would need to cut the roller bracket down and drill a second screw hole to line up with the one already in the pickguard. Depending on how the roller lines up with the existing switch hole, you may need to drill two new holes in the bracket.

The real question in my mind is where you're going to fit the active boost board and battery without routing. Is that something you've already got figured out?

Yep, I was gonna use the board as a neck shim. Kill two birds with one stone.

....

Just kidding. Yeah, I dunno, I was hoping someone here would have ideas. Things like the EMG SPC exist. That might be my best bet. I could replace the tone pot with that, move the tone pot to replace the 3-way switch (with a roller), and replace the volume pot with a push-pull volume pot to engage/disengage the mid-boost. Then the only missing piece is the battery. Perhaps if both pots were of the miniature kind, I could cram it under the control plate?

[Embenny]

You could put the SPC where the tone knob is, and a concentric J-bass knob (or another, I just think those look closest to a stock Mustang knob) where the volume is, without having to use the roller pot mod.



I don't think a 9-volt would fit where the second switch normally goes, unless you widen the route, but that's a potential place to hide that.

If you want something totally nondestructive, EMG makes an external power supply that you can use by connecting your guitar via a stereo cable.

[alexpigment]

Yep, I was gonna use the board as a neck shim. Kill two birds with one stone.

....

Just kidding. Yeah, I dunno, I was hoping someone here would have ideas. Things like the EMG SPC exist. That might be my best bet. I could replace the tone pot with that, move the tone pot to replace the 3-way switch (with a roller), and replace the volume pot with a push-pull volume pot to engage/disengage the mid-boost. Then the only missing piece is the battery. Perhaps if both pots were of the miniature kind, I could cram it under the control plate?

Haha Well, I own a guitar with an active mid boost, and it's a fairly cool option to have, but there may be another way to approach this and get the desired result. For example, if you want the switch position to give you more volume and highs to push your amp/pedals harder, consider making it a "blower switch". In effect, that position will bypass the volume and tone controls (presumably 250k) and go straight to the output jack.

Another option might be to put 1 meg pots in the guitar, then your switch's normal position has a capacitor that effectively takes your resistance down to 250k, and the "boosted" position has no capacitor and allows the full 1meg resistance. You would have to research exactly what values would be needed, but it should be a simple mod.

Lastly, another option could be to have really high output pickups with 4 wires (e.g. Hot Rails), then use the switch to change between coil tapped (partial output) and regular output. I don't know of an easy way to do this with one switch, so you'd probably need to use a switch for each pickup.

Either these are useful suggestions or it's time to break out the router and make a swimming pool route in the guitar.

[Matt_A]

another option is to put the new knob in the hole currently occupied by the output jack, and drill a telecaster-style output jack from the side of the guitar. Not totally non-invasive, I agree, but it opens up some space.

I've wondered why nobody makes a sliding tray for a 9V battery that could be rabbited into the edge of a guitar body, covered with a metal coverplate that get screwed in when the battery is inserted. If you were handy with metal work this wouldn't be a terrible challenge to accomplish, and the cover plate could be combined with the mounting for the jack or adjacent to the strap button, and would be relatively unobtrusive. As long as your active circuit is switched off when the jack is removed you should not need access to the battery so often that removing a screw is a major impediment. I dislike the plastic battery covers that you see on the backs of guitars so often, they're a kludge and subject to accidental opening at the most inopportune moments.

[skern]

Haha Well, I own a guitar with an active mid boost, and it's a fairly cool option to have, but there may be another way to approach this and get the desired result. For example, if you want the switch position to give you more volume and highs to push your amp/pedals harder, consider making it a "blower switch". In effect, that position will bypass the volume and tone controls (presumably 250k) and go straight to the output jack.

Another option might be to put 1 meg pots in the guitar, then your switch's normal position has a capacitor that effectively takes your resistance down to 250k, and the "boosted" position has no capacitor and allows the full 1meg resistance. You would have to research exactly what values would be needed, but it should be a simple mod.

Lastly, another option could be to have really high output pickups with 4 wires (e.g. Hot Rails), then use the switch to change between coil tapped (partial output) and regular output. I don't know of an easy way to do this with one switch, so you'd probably need to use a switch for each pickup.

Either these are useful suggestions or it's time to break out the router and make a swimming pool route in the guitar.

I considered the blower switch, but it's too subtle for what I'm after. I might install it regardless, if I have a free spot in the switch.

I think that switching between 1M and 250k resistance in the volume pots would have more of an effect on treble, rather than mid-range, no?

I'm not crazy about the Hot Rails idea because then my default tone would be only partial output. In my case (playing metal) I always want the vol/tone knobs maxed for better pinch harmonics. It seems coil tapping would impact this, and also kill some treble, which is less than ideal. I forgot to explain in the OP that I would be playing with a scooped-mid sound and the mid-boost would be for instances where I want to regain those mids.

I was messing around with a Metal Zone the other day and I realized that ACTUALLY the thing that I really want is a broad-range mid-boost that ALSO scoops a certain area of the range. I got the sound I was hearing by having the mids totally scooped on the Metal Zone and then adjusting which frequency is being scooped. I loved all of the different scoop sounds.

Before playing the Metal Zone I was looking at this Modboard, but now I'm not so sure it can get what I'm after. (And quite unlikely that it would fit. I would have to remove the tone knob and try to cram the board and battery into that space. Then I'd replace the volume knob with a dual concentric push-pull.) I found a few other onboard things that are in the right ballpark: Artec BCU, QTA, QTP, Starrlabs Spectrum-1.

To be honest, I think what I want is an inverted wah pedal. Like, a sweepable band-stop filter, rather than band-pass. I'll ask around the forums to see if such a thing exists. And If I could fit it inside the guitar, that'd be AWESOME.

[Embenny]

So you basically want a sweepable notch filter, to vary a mid scoop?

There's actually a passive option for that. The good old Gibson varitone.

No battery routing required.

[Shadoweclipse13]

So you basically want a sweepable notch filter, to vary a mid scoop?

There's actually a passive option for that. The good old Gibson varitone.

No battery routing required.

And if you wanted to keep it simple, you could just get a DPDT switch (or push-pull pot!) to have a single capacitor ready to go. You'd just need to figure out which capacitor would do what you want.

[skern]

So you basically want a sweepable notch filter, to vary a mid scoop?

There's actually a passive option for that. The good old Gibson varitone.

No battery routing required.

Hmmm... Very interesting. I'm gonna try to find a store that has an axe with a Varitone so I can test it out.

The only thing that doesn't sit well in my mind is that I'll already be playing with a scooped sound. So if the Varitone is designed to cut out specific frequencies of the midrange, won't I need to boost the mids first to even have mids to cut at at all? I'm also afraid of it having too much impact on the overall output, given that it's passive. I feel like I would need something active in conjunction, OR already have the Varitone engaged for the default tone.

[Matt_A]

Hmmm... Very interesting. I'm gonna try to find a store that has an axe with a Varitone so I can test it out.

The only thing that doesn't sit well in my mind is that I'll already be playing with a scooped sound. So if the Varitone is designed to cut out specific frequencies of the midrange, won't I need to boost the mids first to even have mids to cut at at all? I'm also afraid of it having too much impact on the overall output, given that it's passive. I feel like I would need something active in conjunction, OR already have the Varitone engaged for the default tone.

this might shed some light on the subject
https://www.premierguitar.com/articles/ ... d-extended

[Embenny]

Whoops, disregard this post. I misread something you wrote.

[skern]

I tried the Varitone. I wasn't crazy about it. The output loss was too prominent and made pinch harmonics much worse. I think any method which reduces the output at such an early stage in the signal chain without any boost or buffer to compensate is bound to be sub-optimal. I read this article on the MT-2 circuit. There is a big mid hump before the distortion, and then a big mid scoop after the distortion which is achieved with two peaks in the lows and highs. So it's like, everything is being boosted (of course, it's a distortion pedal) before any scooping takes place. Also, when I was testing it out, I had pedal set to boost the lows and highs a bunch, which further ensures that, when cutting mids, you're not losing too much of the adjacent lows or mids (I believe).

I'm about ready to abandon the idea. I want to use the mid scoop stuff for distorted tones, and I feel that cutting mids is only gonna sound okay if it's happening AFTER the distortion. So If I'm doing it inside the guitar, that's not possible, unless I'm also shoving some sort of gain/distortion circuit in the guitar, and at that point I'm just trying to build a distortion pedal with a mid shaping contour knob that fits inside the guitar. Pretty ridiculous.