Winding a Lo-impedance pickup?

[newey]

Various posters recently have discussed wanting to "wind their own" pickups, and it got me thinking of trying it myself. But(so I thought), why spend time and $$ winding something similar to what I could buy pretty much anywhere. If I'm diving in, why not aim for a coil that is not readily available? So, I began thinking about winding a low impedance pickup, like the LP Recording/Professional models had back in the day. This would go into a dedicated Lo-impedance guitar designed to plug into a PA XLR input, with maybe the option to plug into a regular guitar amp??? (Still pondering that aspect . . .).

But, as far as winding the coils themselves, what parameters would I be shooting for? I assume fewer winds, but what would be the range, roughly speaking? Wire gauge? Other materials needing to be optimized for this?

I did not recall anyone posting on this before, if I'm wrong, apologies for duplication. But I'm wondering how the pickup mayvens around here would weigh in on this?

[gckelloch]

Maybe get some P90 parts and these pole screws:
www.philadelphialuthiertools.com/misc-hardware/threaded-rod-pickup-magnet-2-m5x-8-x-63-length-set-of-6/

They don't reduce the high end as much as Steel screws. You can easily swap magnets in P90 housings. They sell A2, A3, A4, A5, etc. I guess you wouldn't need to charge the screws if there are magnets connected to them? I dunno.

I think Bill Lawernce (Willi L Stich) said he used 38AWG wire in his first Lo-Z pickups installed in his signature Framus guitar back in the '50s. You could easily wind that by hand. I think you only need 200~300 winds. Thinner wire would produce a more sensitive and efficient coil, but you'd need a shorter bobbin to reap the benefit. Bill had told me a square coil cross-section is optimal. You can then adjust the pole screws and coil height for note timber.

Thin Cu-shielding around the coil might actually make an audible difference in EMI noise since the coil would be so small. I assume the noise reduction to noise generation ratio would be much higher? Maybe not. You could add Cu tape layers around the coil and look at the results through an SPL graph. Make sure to keep the coil in the same spot and angle when noting the results. You'd probably need at least 5 tape layers or so, and the higher harmonics will come down first. When you decide on the noise reduction level you want, you can add the same amount of layers under the pickup and look at the results again. It shouldn't affect the string sound very much, but you'll have to see. I assume the shielding should be grounded, but the tape under the pickup doesn't necessarily have to be grounded since it's so far from the coil. Doesn't hurt to ground that too, though. You can also use 5~10 layers of Al tape under the pickup and the pickguard to reduce noise from poorly shielded rheostats, while also reducing the harsher upper-harmonics. I don't know how Al would sound wrapped around the coil. That might significantly reduce highs or something.

[ms]

The current Les Paul Recording guitar (http://legacy.gibson.com/Products/Electric-Guitars/Les-Paul/Gibson-USA/Les-Paul-Recording.aspx) uses a transformer to achieve "balanced" output  at low impedance and also high impedance (presumably single ended).  It is not clear whether the pickups are inherently high or low Z.
 
One relatively simple project would be to wind a balanced pickup that could drive a microphone input on your recording interface.  Is this what you have in mind?

[newey]

Dec 31, 2021 19:55:05 GMT -5 ms said:

One relatively simple project would be to wind a balanced pickup that could drive a microphone input on your recording interface.  Is this what you have in mind?

Exactly, or into a mic pre/PA combo. Having switcheable impedance outputs was just a thought, you're right, would need a transformer a'board, and I'm not looking for that level of complexity. Could probably do that external to the guitar, at some point down the road, if desired.

gckelloch: That's the type of info I was looking for, thanks for the extensive discourse. Much to consider.

[gckelloch]

I may be misunderstanding something, but to eliminate line noise via a balanced line wouldn't you just need a length/thickness of insulated wire equal to the wire going to/from the pickups and to the secondary + and - lugs on the input jack? You could wrap such a wire around the pickup leads so it returns at the connections for each pickup. Whatever noise is picked up by either length of wire after the pickup would be canceled when the phase is reversed at the mic input, no? The signal from that wire loop would only be equal to the signal from the other wire going to each pickup, so it wouldn't cancel the pickup signal, right? I think the transformer in the LP recording model was only added so it could be used in Hi-Z preamps. Bill had also told me the transformer was very poor quality in that guitar. He was already chief engineer at Gibson, Nashville at the time.

[Charlie Honkmeister]

Hey there Mr. newey,

Here's a couple of tips.  I did a whole journey on low impedance pickups a few years back.

1.  Pickup Makers Forum -  there's a years-long thread and significant other threads on low-Z pickups.  A search will get you lots and lots of information.  Of course the ultimate low-Z pickup is a single turn of very thick (so very low resistance) wire,  or making the string itself the primary loop.  The Lace Alumitone is a single turn loop (actually, two for humbucker) that actually is a transformer primary, with the secondary a conventional coil with very thin wire.

Pickup Makers Forum

2.  Personal experimentation

I was finding during my own low-Z experimentation that AWG 36 works well for both normal Strat-sized single coil bobbins and humbucker bobbins.  Use "normal" pickup parts, magnets, bobbins, etc. Just fill the bobbins up.  You end up with around 50-70 ohms DC resistance, 100-200 ohms source impedance,  and that works nicely with a 600 ohm to 1K Ohm balanced mic input since the rule of thumb of source impedance to preamp input impedance is usually 1 to 10,  but you can get by with 1 to 5.

It's really easy to get a balanced output with a humbucker design - just invert the phase of one of the coils relative to a normal humbucker,  and use the center coil split point as ground.   But volume and tone control become more problematical since you have two signal phases.   You can run single-ended inside the instrument, like Gibson did with the Les Paul Recording models, and use an external transformer to convert to balanced.  here's a thread on GNuts2 about the LP Recording model with a schematic:

Gibson LP Recording Thread - GNuts2

Pickups with this voltage signal level need about 25-35 dB gain to be the same level as "vanilla" to hot  hi-Z pickups.   That's absolutely no problem for a mic preamp.  If you also want a "normal" output on the instrument, there's a couple of ways to do it.  It's tough (but possible) to get an onboard preamp with that much gain,  that's also quiet,  and does not pull so much current that it would suck down a 9V battery fairly quickly.  Another approach to on-board is possible.   Mini or submini audio transformers with a 1K primary to 10-15K secondary (or vice versa) can get you up to about 17 dB of this noise-free. A simple JFET preamp can get you the other 6-18 dB or so without too much noise.  Putting the tone and volume after the transformer or after the preamp lets you get closer to "usual" or easily-sourced values for your volume and tone pots and tone cap.  

The Fishman Fluence pickup line is built low-Z,  with a multilayer PC board with printed wires and stacked,  then has an active preamp with tone shaping to supply the gain and emulate the resonant peaks of conventional pickups.

 

3.  Do you need "Flat to 20K" ?

The self-resonance of these pickups is way up in the ultrasonic range - 25-40 Khz.  This means that by themselves they are ruler-flat in the audio range we are able to hear.  That's OK if you are going to do all your tone shaping with electronic EQ.  But for a guitar,  do you need any output from the strings over about 7-9 Khz?   The answer is,  No.  There's lots of funky noise up in and above that range you don't want to hear - string squeaks, pick noises, etc.  Also, metal strings go non-harmonic up there just due to physics and so those "harmonics" aren't useful.   Also,  for the normal electric guitar sound we expect,  almost all guitar speakers drop off a cliff in output over 5 Khz.   

Don't let me talk you out of making low-Z pickups for that reason -- you can get wonderful,  acoustic-like clarity and immediacy out of these pickups, and EQ is relatively easier with a flatter source.  But be ready to apply EQ to get back to something that also works as regular pickups do with "normal" amps and pedals.

Take care and Happy New Year,   -Charlie

[newey]

Thanks, Charlie Honkmeister-

I remember the thread on the LP recording. The fact that I will likely never own one is one of the reasons I brought this up. I will have to peruse the pickup makers forum, never looked at that before.

[mozz]

 I have a few various spools of litz wire and was going to experiment with this, one day. More ideas than time.

[newey]

Jan 1, 2022 15:23:59 GMT -5 Charlie Honkmeister said:

It's really easy to get a balanced output with a humbucker design - just invert the phase of one of the coils relative to a normal humbucker,  and use the center coil split point as ground.   But volume and tone control become more problematical since you have two signal phases.

Not quite following how that would work. Is the second coil like a "dummy coil" then?

[gckelloch]

After some research, it looks like I confused the wind count with the impedance. 200-300Ω Z sounds about right. This veteran expert at the MEF’s claims to know the specs of an Alembic Lo-Z pickup: music-electronics-forum.com/forum/instrumentation/pickup-makers/3886-les-paul-lo-z-pickups?p=89910#post89910

I wouldn’t know the impedance of that pickup because of a few factors, but 1~1.5k turns of 40AWG could add up to 500Ω DCR. I also read you’d need 1-2k pots to adequately damp the ultrasonic peak for that pickup. That’s about 1/8th the wind count of a Strat SC. To make the most of the coil, you want as much of it up close to the strings as possible. It may also increase the lower to upper string harmonic ratio so the note timber will be warmer. Again, lowering the coil and raising the poles will thin it out. You could fit that amount of wire into a ⅛” bobbin height space and the coil should still be thinner than a Strat coil. That would place the lowest harmonic cancellation on each string up a bit higher, but the note timber may be thinner as well. You might try a 1/10” height instead.

You might try getting a cheap chinese set of plastic bobbin SC’s. Remove the coils and poles. Cut the bobbins in half. Then reshape and glue the bottom back on so the coil space is ⅛”, and wind away. You’d probably have to put some tape inside the pole holes so those FeCrCo pole screws won’t slide out. They may raise the impedance and inductance substantially more than AlNiCo, so you could try ~700 winds if 1k winds lacks highs. I don’t know what Alembic used for poles. There may be some high end roll off even with 700 winds since Fe has that effect. Easy enough to swap in AlNiCo poles to compare.

Charlie makes some good points I'd like to address.

First, I don’t see the need for a transformer unless you want to plug into a Hi-Z input. The point of a balance line is to cancel any line noise not rejected by shielding. I don’t see why just connecting one of the balanced leads from the guitar jack to ground wouldn’t achieve that. The EMI from a SC pickup would likely be louder than the noise from a 10-15’ shielded mic cable anyway, but you might as well cancel what noise you can.

The Fluence pickup coils are still pretty tall for Lo-Z pickups. They sound just a bit warmer than most Strat pickups to me – about like Wilde L280’s regarding lower harmonic strength. Technically, they may be a bit more sensitive, but the transient response is going to be more limited by the amp circuitry and speaker, so that aspect doesn’t really matter. There may be an audible difference in phase angle with less wire though, but we’d have to know the velocity factor of the wire to know that. Either way, the signal contribution of the winds or PCB layers drops by 60% every 2x the distance from the strings. That’s why a shorter denser coil closer to the strings is more efficient, sensitive and dynamic.

Guitar string harmonicity depends on the gauge and compliance of the strings. I find some of the more compliant string alloys I use have a sweeter high end. Increased tension and/or rigidity causes higher harmonics to go sharper. Lighter-gauge/more-compliant strings will have more harmonious higher harmonics. I’ve compared the plain Steel strings of the same gauge from several different brands, and some definitely sound warmer and sweeter than others. Thicker strings may have less higher harmonics, but they also have shaper ones, so that’s not necessarily the answer to getting sweet sounding highs. Low magnetic string pull is a big factor as well.

The more recent Sfarzo string formulas have sweet highs, but I’m still waiting to try the 9-42 sets of Touchtones I got. The other Sfarzo 9 high E’s I’ve tried sound sweet into the 8kHz range on my 25.5” scale guitars compared to some other brands. It could be the Steel quality and annealing, and/or the Ni-coating thickness. I suggest trying such a set with your Lo-Z pickups. Surely there are other plain 9’s that sound nice, but I haven’t tried them all. I’d use 10-46 sets on 24.75” scale guitars. The newer Sfarzo’s 10’s sound sweet too.

It’s true that many guitar speakers roll off by 5kHz, but some 12” speakers are audible to ~8kHz, and some 10’s even higher. The original AlNiCo Blue was a radio console speaker. It rolled off just above 4kHz for speech intelligibility. It became a standard for guitars because the generated higher amplifier harmonics clash with progressively sharper string harmonics, but it’s not an issue for clean sounds and sweet sounding strings. I also suggest using 0.015-0.03” thick Aluminum shielding under the pickguard for a softer/less-metallic upper-midrange, particularly with Steel saddles. There will likely be some high end roll off with those FeCrCo pole screws. Pushing 4.2-4.5kHz a bit will offer a classic Stratty tone. Pushing 8-10kHz will be like an acoustic guitar.

[Charlie Honkmeister]

Jan 1, 2022 17:16:34 GMT -5 newey said:

Jan 1, 2022 15:23:59 GMT -5 Charlie Honkmeister said:

It's really easy to get a balanced output with a humbucker design - just invert the phase of one of the coils relative to a normal humbucker,  and use the center coil split point as ground.   But volume and tone control become more problematical since you have two signal phases.

Not quite following how that would work. Is the second coil like a "dummy coil" then?

Sorry, that was confusing because I threw together two different ways of thinking about doing this.    My bad and I hope that the following helps. 

If you build a low impedance humbucker and let's say, just wire it exactly as a regular pickup would be with both coils in series, a ground and a single output,  then to convert it to get two balanced outputs, one output from each coil,  you just need to move the ground to the center series link between the coils;  your old ground wire is one coil output and your old "hot" pickup output is the other coil's output.

In a regular single-output  ("single-ended") humbucker, the two coils are connected electrically out of phase overall and the magnetic polarity is opposite between the coils,  so the two reversals cancel for the string signal,  and the induced current from the string motion on the single output is in phase,  while the electrical hum/noise from each coil is out of phase and cancelled inside the pickup. 

When you use a balanced input with 2 connections ("legs") and a ground,  you do the exact opposite. 

When you go balanced with a pickup, you actually want the coils to be in phase with each other so the hum/noise induced is equal on both outputs,  and then that will cancel out downstream, because a balanced input rejects the same signal on both input legs and accepts differences between the two input legs.  For balanced operation, you  want the induced current from the strings from the different coils to be out of phase, or as different as possible, on the two coil outputs to the balanced inputs.  So if the coils are in phase, then the two coils' outputs for string motion will be out of phase like you want, again  because of the different magnetic polarity present on each coil.  

An overall way to sum it up is that in a single-ended humbucker,  the hum and noise is cancelled inside the pickup,  but in a balanced output humbucker,  the hum/noise comes out of the pickup, exactly equal on both outputs and is cancelled by the way the balanced input works. 

This is the same idea for any hum/noise picked up in the balanced connecting cable;  the induced hum/noise will be equal on the two signal wires in the cable and be rejected as well.  Low impedance is much less susceptible to induced noise/hum anyway,  so this is why low impedance balanced inputs are used for microphones and professional line-level audio connections,  especially for microphones.

I hope that somewhat mangled explanation helps;   I basically don't have a drawing tool handy to show this easily,  but could be motivated to draw this up if there's enough interest.  

[newey]

Thanks, that does help.

[gckelloch]

You'd need dual-ganged pots and switches in the guitar to cancel the noise from two coils via a balanced line. I'd just make a series wired HB with ~1k or so winds of 36-40AWG wire if you want hum-canceling. Maybe try 38AWG as a compromise?

There are ways to make stacked pickups that don't have significant losses, but it gets complicated. I still think the Wilde NF series and Dr. Scott Lawing's Zexcoils are the best designs with the least losses, but they require precise geometry and specific alloy formulas to realize. You could try stacking two very short bobbin SC's with the poles touching a grounded ~5mm thick Steel or Permalloy bar between them, as a crude version of the Wilde NF series, but who knows how that will sound, and I think it has to be charged via opposing polarities from both directions when assembled. Again, it won't work right if the geometry is off.

I'm pretty sure mic's are low impedance because smaller coils have less mass, and much longer cable runs can be used b4 the cable capacitance affects the audible range. Whatever EMI is picked up by any coil will be amplified along with the intended signal, so I don't think there is any better s/n with a Lo-Z coil unless more of the coil can be situated closer to the magnet or magnetic signal generating source. That can be made so with smaller coils, and more so with denser ones, but the reason balanced lines are used is because the signal from a Lo-Z mic is so weak that the noise picked up from the cable is that much louder in comparison, and very long mic cable runs are now commonplace. They are also used in studios to eliminate any noise added to line level signals because there is so much AC noise generated from all the equipment and running all the signal cables perpendicular to power cables might be prohibitive.

P.S. Rather than bother with a stacked HB design, try holding one of those 1/10" thick Aluminum pie tins in back of any of your present SC pickups and listen to the noise decrease. I assume it would make much more difference with a Lo-Z coil, offering maybe another ~12db noise reduction to 1k winds of 38AWG compared to 8.5k winds of 42AWG. The smaller coil would be more efficient if it's all closer to the strings by maybe another ~6dB, and higher permeable poles would further increase efficiency so you might get ~20dB better S/N than an unshielded A5 Strat pickup. That's PAF S/N territory. You could then use an Aluminum pickguard, and cut pieces out of the pie tin and screw them to the bottom of the pickup cavities. That's not too difficult a task. There might be some upper-mid loss, but that sounds nice -- more "syrupy".

[ms]

A regular humbucker does not reject electrical noise.  You can think of this  as a reversal of connections introducing two new paths which have opposite voltages across them.

How can an aluminum plate replace magnetic hum bucking?  What are you trying to do with it?

If I were making a low impedance hum bucking balanced pickup, I would use a stacked or sidewinder design for single coil sampling, wind both coils with center taps,  and connect the coils in parallel (so that both center taps can be grounded).  Each coil should be twice the target impedance, and I would just accept some signal loss from paralleling the coils, counting this as part of the cost of obtaining very good cancellation of both magnetic and electric interference.  No shielding should be necessary because of the good cancelation, but I would probably shield anyway because I think that the effect of eddy currents would be much reduced in a low impedance non-resonant design.  To that end, I would make sure that the coil impedance is correct so that the load introduced by the mic input has sufficient damping so that there is no resonance peak.

[gckelloch]

The paramagnetic nature of Aluminum disturbs the magnetic field, but it won't significantly affect the string vibrations within the coil if only under the pickup because the field from the string is much weaker there than at the coil. It may affect it even less if the coil is very short and up close to the strings. I'm only speculating that EMI would be more reduced in relation to a smaller coil. Either way, you need substantial thickness to hear a difference. Ever try it?

I read on MEF that 1~2.5kΩ pots are needed to sufficiently damp the ultrasonic peak of a Lo-Z pickup. I don't know for sure, but why would there be no resonant peak into a mic preamp?

[Charlie Honkmeister]

Mike,  that's certainly another way to do it and it probably yields theoretical and practical advantages.  

But from my experimentation a few years back,   just "vanilla" humbucker construction,  with the bobbins wound with AWG 36, even running single-ended, with normal precautions on guitar shielding and grounding,  yields an exceptionally quiet signal anyway with a decent mic preamp,  or transformer/medium gain preamp.  I used an ART Tube MP Studio preamp to test.

[ashcatlt]

I feel like you'd ought to be able to get balanced output just by letting the pickup float. The bottom of the coil goes to the negative wire, top to positive, and the "ground" wire in the cable is connected to whatever shield ground point you've got in the guitar. V and T would be connected across the coil.

[newey]

Based on Charlie's experimentation, I figured I wouldn't worry about balanced output. But if it's that easy, sure, why not?

[gckelloch]

I took some SPL graphs of two pickups with and without a 0.08” thick Aluminum pie tin over them, and then with white noise playing through an earbud pressed against a pole screw set at ⅛” above the top of each coil:

drive.google.com/drive/folders/0Bx0CnqsQz_uYblRTLTQwam5FS2s?resourcekey=0-HmA9RFQMWz4AYmvFTPpD2Q&usp=sharing

The pie tin reduces the midrange EMI harmonics by as much as ~9dB, and almost as much through the 2~4kHz critical hearing range. The high-end peak corresponds to the resonance peak of each pickup. The signal is up ~3dB at the resonance of the Wilde MC-T with the pie tin over it. Perhaps the tin is acting as an antenna at the pickup resonance because it was poorly grounded? That might not have happened if the tin was under the pickup. It didn’t happen with the GFS P90, but the braided wire shielding was definitely touching the tin in that case. The MC-T also has very thin Cu-shielding under the coil and on the baseplate, so the pie tin may not have made as much potential difference anyway. In either case, much thicker Al shielding would be required to substantially reduce the lower EMI harmonics. Perhaps one could stack 2-4 such pieces under the pickups, or layer 50~100 pieces of Al tape? Still easier than making a stacked SC that might have unexpected losses.

Notice in the white noise SPL’s (without the pie tin on top) that although the P90 is over 2.5x the inductance, the MC-T has about the same average output, yet with a slightly stronger peak and much stronger low end. Both pickups have Fe alloy cores - the P90 being Steel and I believe the MC-T is Permalloy - so permeability is very high in both cases, while high-end roll-off should be less with the MC-T. Also notice that the EMI harmonics, but for 60Hz, are considerably lower in the MC-T, while the low end of the white noise signal is considerably higher. I attribute that to the much smaller denser 46AWG coil increasing lower harmonic strength at the same distance from the source. The pole screw Gauss of the MC-T is likely not much higher, if at all, than the A5-powered P90. It’s definitely less than an A5 Strat pole piece, so I don’t think Gauss is a significant factor. However, the magnetic field is peculiar around the MC-T pole screws. A screwdriver does not stick to the screws, but sticks strongly to the bushings right below them. So I really don’t know what’s up with the pole screw alloy, but string pull is low, and raising the pole screws while correspondingly lowering the coil thins the note timber without reducing higher note harmonic output – same as with a P90.

I don’t mean to harp on about the Wilde MC’s, but I wanted to give an example of how a small dense coil up close to the strings improves S/N and lower-harmonic strength. Most players assume P90’s have strong bass, but not compared to the MC’s. It’s actually just the lower note harmonics that are stronger i.e. any stronger magnetic vibrations are more emphasized at a given distance.

[Charlie Honkmeister]

Jan 2, 2022 18:29:18 GMT -5 newey said:

Based on Charlie's experimentation, I figured I wouldn't worry about balanced output. But if it's that easy, sure, why not?

Yes,  floating balanced would work too.  I experimented with floating (not very much) but that was with a 1K:10K submini audio transformer so there was a complete loop between the pickup and transformer.

You can in fact go single-ended and go into a balanced input,  but you lose 6 dB (1/2) voltage signal and are more susceptible to noise from long cable runs or crapola shielding in the cable.   This may or may not be an issue depending on your setup .  The mic preamp I used, the ART Tube MP Studio, has both single-ended and balanced ins and outs;  ART is still making them and they aren't super expensive .

[Charlie Honkmeister]

gckelloch,

Just FYI,  I am also a big fan of Lawrence/Wilde (Becky and Shannon) pickups and have L-500,  L-90,  and Microcoils in my stable. 

[gckelloch]

Jan 3, 2022 11:06:29 GMT -5 Charlie Honkmeister said:

gckelloch,

Just FYI,  I am also a big fan of Lawrence/Wilde (Becky and Shannon) pickups and have L-500,  L-90,  and Microcoils in my stable. 

I have several different sets as well. Did you adjust the pole screws on the MC's for each string and position? Seems like people are afraid to do that for some reason, and then they complain that they are articulate enough. I had to put slivers of electrical tape in the screw holes of my MC-S set from 2009 so the pole screws stay snug, but the pole screws in the MC-T set I just got are very snug as is. I also use 0.015~0.03" thick aluminum shielding under the pickguard of a few guitars for a sweeter tone after learning about it from Bill's site.

P.S. I fixed the link to the folder for the SPL graphs in my last post.

[guitarmd]

I don't understand impedance. I'm a simpleton.

However, I ordered a Triton Audio BigAmp Piezo DI box recently to use with a piezo neck pocket pickup I installed, as an experiment. It runs on 48V phantom power. Simply plug in your 1/4" cable to one end of the Triton, then the other end is an XLR out. So XLR cable to connect from the Triton to -- in my case -- my 2i2 Scarlett Interface. Turn on the phantom power and you're good to go.

Eventually I figured I'd try making a low impedance magnetic pickup and test it with the DI box, just to see what happened. I also decided to make it a noiseless stacked coil.

It's a Strat pickup. Alnico 5 rod magnets, .719" height for all of them. The top coil is .130" tall. The bottom coil is about .280" bottom. Build it by notching a top flatwork piece on both sides (I use a Fret Slotting Saw, about .023" teeth on it). I chuck it in a small vise and make the notches that way on either end of the flatwork. Install the flatwork with spacers, so the bottom is .280," then install another top flatwork piece so the top coil is .130". I figured having a short top coil would be good.

200 turns of 38AWG on each coil. Counterclockwise one coil, clockwise the other. Simple.

It sounds good. I'm not sure if the Triton BigAmp Piezo is the correct DI box to use. It has, I think, a 7.5 mega-ohm input, or something like that. Again, at this point in time I am completely uneducated about impedance.

But I have made hundreds to thousands of pickups and this low impedance one was a piece of cake. It sounds great. I didn't pot it, and it is *extremely* microphonic. Though unpotted pickups all tend to be extremely microphonic in my experience.

Just using stock 250k pots. It sounds good plugged in. I'd love to learn more so I could refine this and either purchase a more appropriate preamp, or make one, or something. I am dumb as a bag of rocks when it comes to all this impedance matching and electricity stuff. All I know is the low impedance pickup is dead quiet and gets a great clear tone through this BigAmp DI box thing and into my interface.

It is a little bass heavy though. I like the idea of Low-Z pickups for recording. I've made tons of passive stacked noiseless pickups, and they can be OK. But for recording purposes I'm really thinking Low-Z is the way to go, just based on the limited audio testing I've done. There's just some extra clarity to these that passive pickups don't have, which is perhaps the flatter EQ response, or something. I don't know what it is but I like it. And always a fan of using less wire to make pickups...except for when I'm making my 18,000 - 18,500 turn monster Strat pickups

[kitwn]

A high impedance source, such as a piezo microphone, produces an output voltage but can provide very little current flow to back it up. A low impedance source can provide significant current. A high impedance input, such as your pre-amp, will draw very little current from the source and so can be used with any kind of pickup.

The trouble starts when you try to feed a high impedance source to a low impedance input. The input wants to draw current which the source cannot provide and it's voltage collapses to nothing. In effect you have put a short circuit on the source. Another example of this is a capacitor microphone. Great audio quality but such a high source impedance that even a short length of cable has too much capacitance (and therefore too low an impedance for the higher audio frequencies) to be used without mounting a buffer amplifier right by the capsule, inside the microphone body. The buffer amplifier has a very high impedance input but has a low impedance output so it can provide the current that the source itself cannot. This is why you need the phantom power supply on a microphone input.

Kit