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I'd like to add a volume potentiometer to an acoustic guitar pickup. The pickup has an endpin preamp.

Part 1: Volume Pot
I suspect this is pretty easy, but I have no idea what value the potentiometer should have, and what to look for in potentiometer specs to make sure it will not be noisy.

The pickup is a magnetic pickup from Shadow Electronics, the Shadow NanoMag. They have an optional big ugly volume and tone control module to mount in a soundhole. My two problems with it are that they are expensive and they are designed to fit "normal" round soundholes. Well, Tina Turner never ever does nothin' nice and easy, and I seem to never ever do nothin' approaching "normal." See, I can't even use the word "normal" without putting it in quotes. My soundhole is offset. And elliptical. And, I don't even want a volume pot there if I could make it work. I want to cut a slit in the side of the guitar, upper bout, and mount a thumbwheel potentiometer.

Like one of these:


So, 10k? 500k? Anyone have a clue what value I will need? Is it one of those things where, if Shadow won't tell me, I'll have to experiment? Is there a simple schematic for wiring these?

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Part 2: Tone Pot
I suspect this is not so easy. Again, I'd like to use a thumbwheel pot that looks identical to the volume pot, and I know this will also entail making a small circuit of a few components. Cain't be that hard, can it? Anyone have a clue where to send me for info? Most of what I can find is for electric guitars, but then, this is a magnetic pickup so maybe it doesn't matter.

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Part 3: Volume and Tone Pots for a K&K Pure Western Mini Pickup
OK, let's do it again. So the info I'm looking for on the Shadow NanoMag might just be found on an electric guitar schematics-r-us website, but what if I want to do the same thing for a K&K piezo pickup?

I'd be very appreciative of any and all help on this.

Thanks,

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

http://www.stewmac.com/cgi-bin/hazel.cg ... fo/fi.html

http://www.stewmac.com/cgi-bin/hazel.cg ... fo/fi.html

There are the basics, with those mini pots in your picture the three middle lugs are the "action" lugs, while the two outer lugs are the ground plate, usually you solder a ground wire to the body of each potentiometer, on yours you solder your ground wires to the outer lugs, they can also be used to screw the pot to a wooden base. Unless someone chimes in here it may be a try and see to find the correct value, or ideally shadow/k&k will respond to an email and tell you what will work best.

http://www.stewmac.com/freeinfo/Electro ... ntrol.html

A tone control is also pretty easy, the only component you need in addition to the pot is a capacitor. You may need to fish for a value that works well, but they are cheap.

http://www.stewmac.com/freeinfo/Electro ... -1800.html

There is a simple wiring diagram for one volume and one tone that would work. Same thing goes for the piezo, it is just a matter of using values that do what you want and have a normal feeling taper, it is unusual to have a tone control with a peizo pickup, but that doesn't mean you can't do it.

Wiring seems like magic for a while, until it slowly sinks in, let me know if i am being totally confusing or if you need more specific info.

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Jordan Aceto
Ithaca, NY

Dont know about the shadow ... but the KK is easy to find out info on .. simply phone them up and talk to Dieter.

I use KK pretty mcuh exclusively, and use the outboard preamps.. volume/tone at your fingertips, and you can use one pre for multiple guitars .... no batteries inside the guitar either.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Thanks very much Jordan! I saw a whole page of links at MIMF, including StewMac, and followed a dozen links off onto various sites. Figured I'd get to StewMac sooner or later, but should have gone there sooner! That appears to be just what I needed: Pots 101

I have an Alvarez Yairi with a 3-band EQ and an undersaddle piezo pickup. Is that uncommon for acoustic piezos, or do you mean it is just uncommon to wire in a single tone pot to a piezo?

Thanks again,

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

Thanks, Tony!

I will call Dieter.

The Shadow NanoMag comes with an endpin preamp, and as far as I can see I could not buy one without it. So, I already paid for the preamp...

I had thought about getting a D-Tar Mama Bear, and might some time in the future, but at least for this one experimental guitar that will sport a NanoMag plus a K&K Pure Western Mini, I might just as well use the K&K endpinpin preamp as well. This guitar has an access panel, so it shouldn't be too big of a pain.

If this combination of pickups does what I hope/expect it will, perhaps I can look further into getting the NanoMag without the preamp.

Thanks again,

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

The three band eq on your yairi is what is called an "active" circuit, meaning that it recieves power from somewhere (the battery) and is capable of cutting frequencies or boosting frequencies. A simple tone control like the type found on electric guitars is a "passive" circuit, it requires no power to do its job, but can only dump high frequencies to ground, not boost anything, this type of control makes your sound seem more bassy as you turn it down, but all it is really doing is removing trebles. An active eq section is common on acoustic guitars, passive tone controls not as much, again that doesn't mean you can't do it.

Sorry if i am throwing information at you not fully understanding what you are trying to achieve, you could fathomably build a simple active one knob tone circuit, it would be way trickier than just a volume and tone knob though, there would be some homework involved.

Tony is right that the easiest and probably best thing to do would be to get an outboard preamp, but if you are committed to the cool little stealth knobs coming through slits in the side, i understand, because it sounds cool!

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Jordan Aceto
Ithaca, NY

Hopefully you're already clear on the difference between magnetic and piezo pickups. Magnetic pickups put out more signal and can be configured with volume and tone controls with no additional circuitry required. Piezo pickups put out a relatively weak signal and must be amplified before any volume or tone controls are added. As Jordan said, once you've added the circuitry for a preamp, it's not a big deal to add in an active circuit for an EQ although you can also just follow the preamp with a pot/cap and dump the higher freqs to ground. I have built and installed onboard preamps for piezo pickups but for personal use I only use offboard preamps.

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Steve Smith
"Music is what feelings sound like"

Hi Steve,

The NanoMag is an active magnetic pickup. If I understand that correctly, it's not just a weak signal in need of amplification, but there is circuitry in the pickup that actually needs power (voltage from a battery.) That must mean the endpin preamp version of this particular pickup is actually a 2-way street, both supplying "phantom" power to the pickup as well as receiving the signal from the pickup and putting that through the preamp.

I am unsure how an active mag pickup needs to be wired to include pot(s) for volume (and possibly tone.) Seems like the endpin preamp is not intended to allow someone to break into the circuit after the preamp, which is where I guess the pots would have to be wired in. I guess the Shadow version of this NanoMag that includes the preamp with phase invert switch, volume, bass & treble controls in the soundhole module then must just have a plain 'ol vanilla jack. Again, there is no option to buy this pickup without a preamp, so I either waste the money on the much more expensive soundhole module version and tear that apart (keeping the preamp and rerouting the circuit to use my own pots), or else try to break into the circuit at the (cheaper) endpin preamp version. Maybe that really means tearing the preamp out of the endpin preamp, and just replacing the endpin jack that will probably be destroyed in the surgery.

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Now, the K&K Pure Western Mini is a separate story, but the fact that I want both that and a NanoMag on one guitar pretty much makes it crazy to have an outboard preamp for the K&K and an onboard preamp for the NanoMag, so I guess I am looking at the option of the K&K called the Ultra Pure Western, then adding my own volume pot (and maybe a tone pot, even if it is not terribly useful to dump the higher frequencies.)

I want each pickup to be completely independent, no "blender" or overall tone shaping.

Actually, if I could find a high quality, low price, tiny 3 or 5 band EQ component with sliders that I could mount for each pickup (again, through slits in the guitar side), I would sure consider that option rather than a simple tone pot.

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

Dennis,

The active mag would be a plenty strong signal. The K&K Pure Western Mini (my current fav by the way) will, as you know, also need an amp. Your problem will be getting both of the signals out. You have at least 3 choices: 1) 2 seperate mono output jacks, 2) a stereo output jack, or 3) blend the two outputs then use a mono output jack.

I've never used the double jack solution-just don't want the extra hardware.

The stereo jack works fine except for cord availability and you would have to have two seperate amps in your guitar. I ended up custom making my cords which is fine until it goes bad and you can't just grab a spare.

I haven't used a commercially available circuit to blend mag and piezo signals; for this application I built a custom circuit based on an MIMF design. As a possibility, you might check out how LR Baggs recommends combining their piezo bridges with mag pickups; maybe their CTRLX http://www.lrbaggs.com/html/products/preamps_ctrlx.shtml. They say the CTRLX works with the T-Bridge, which I've used before and is just six piezo elements in parallel, so it should work with the K&K Pure Western Mini. I'm sure there are other options out there as well.

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Steve Smith
"Music is what feelings sound like"

Thanks, Steve.

My vision for this is two mono jacks, mounted on the access panel cover. I want separate signals, and I think that there may be times I am glad, at an amp or board, that I have two discrete signals without having to split from a stereo cable. I don't mind the double cables. So, blending is not an issue, or desired (at the guitar.)

I'm sure there are commercial preamps with EQ circuitry that would do everything I want (well, I'm not positive about feeding the voltage to the NanoMag that it needs), but again, I already am forced into buying what is touted as a very good preamp for the NanoMag, so all I really need is a preamp for the K&K pickup (which is only about $50 from K&K dealers.) That only leaves the question of pots.

No offense to anyone, but I have never seen a combination preamp + EQ module that I would want sticking out of the side of my guitar. I think they are all so big, and ugly, and plastic...

Beyond the internal preamps, volume and maybe tone controls on the guitar are a bonus, but the technology for that (or at least the component cost) is so low that I'm exploring the DIY aspect. I should be able to create a more aesthetic (to me) set of controls as either thumbwheel pots or slider pots coming through slits in the guitar side.

I'm lookin' round the 'Net for schematics for a simple but clean EQ circuit (3 to 5 band)...

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

http://www.mimf.com/library/marchesini_mimf_preamp.htm lots of homework required, volume, bass, middle and treble controls

http://www.mimf.com/library/catalog_ele ... .htm#piezo root around in here for a while

These are from "the other forum", you probably need to log in to see them.

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Jordan Aceto
Ithaca, NY

Well, one thing that I discovered is that the slider pots that we are all familiar with from graphic equalizers, (in the correct spec to work for a guitar EQ circuit), are generally too long to work on a concave surface such as the shoulder of the upper bout of a guitar. Might work on flatter curves, like some areas on a dred, but you may be forced to mount them in a less than ideal location. Round pots for tone, well, three wouldn't look too bad, but I'm already convinced that a 3-band EQ is not enough for a guitar. I think the mids alone need to be divided into 3 bands to get much control.

So, I'm left with thumbwheel pots, if I do EQ on the guitar. In my mind, thumbwheel pots are fine for volume, but not ideal for EQ controls, because you can't just look at the controls and know how they are set.

Gears are still turning in my head...

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia