Pickup made out of mini transformers

[perfboardpatcher]

Hi,
Just to show you something I've been working on.

I've found some mini transformers that we're just small enough to be used as single string sensors. I've ruined a few of them, but 12 out of 17 ain't that bad. First I had to remove the laminates, then I didn't bother to remove the tape and cut and sandpapered the coil/bobbin till it was small enough.

Primary and secondary windings have to be connected in series and in phase. With the help of a resistor and a capacitor I built a series resonance filter. The test setup is slightly different from the schematic I've posted. (Signal generator - resistor - capacitor - mini trafo including rod magnet, all in series. Scope probe connected to the resistor/cap node.) First connect up the primary and secondary in series and find the frequency where's the dip. Next do the measurements with the connections of primary (or secondary) reversed. In phase is the one with the lowest frequency.

Although the idea of building a hexaphonic pickup is attractive I've decided to build a split humbucker first. You're looking at an EAD and a gbe pickup. Or a DAD and a GAD, you get the idea.



I could have used the series resonance filter setup to find the resonance frequency and then calculate the self-inductance of the 2 split humbuckers and use the guitarfreak but instead I've used this set up:

To achieve some decent result one has to use mini trafos with sufficient turns of windings. DC resistance is a good indication. Mine had 2 x 45 ohms and 130 ohms. Previously I've made a hexaphonic pickup with the same rod magnets. At that time I used 1100 turns of 0.10mm wire. If I calculate back (inductances!) then the mini trafos have some 2000 turns each.

At the moment I'm using 2 fets and an inverting opamp as mixer. Still work in progress. But I'm pleasantly surprised with the sound and output level of this pickup.

cheers,
pp

[JohnH]

That is a truely amazing piece of work! Questions will follow, but +1 right there.

Have you tried it in a guitar and how does it sound?

John

[perfboardpatcher]

Sure, John, ask your questions.

I've already tried it in my epiphone. For the bass strings pup as well as the treble strings pup I use a 15nF cap and 22k resistor. It sounds similar to my buffered Paf Pro. A passive pickup sound, there's a peak in the frequency spectrum (3400 Hz) and a second order high-cut filter.

The idea is to tweak bass and treble sides separately, have a different peak frequency and eq for bass and treble.

I haven't started to tweak yet but I haven't encountered fatal flaws that want to make me stop the experiments. The string balance is excellent. I presume the transformers have to be potted to overcome microphonics. I did autopsy on the dead ones. The windings look pretty tidy with thin wire like in regular pups and in fancy colours like blue and green. Have I told you that I could get these transformers for 50 eurocents a piece?

[Deleted]

wow!

[perfboardpatcher]

Still working on this...

I had to remove the sustainer circuitry on the epiphone. New are the 2 mini-dip switches to select the resonance frequency for bass as well as treble strings. (2kHz, 3,4kHz, 5kHz).

I built 2 circuits to do A/B-tests. After the half humbucker - mini-dip - fet stage the signal is split. Signal 1 is a direct mix (a simple inverting opamp) of both half humbuckers. Signal 2 is buffered after the fet stage and then there's a notch filter (ic gyrator) to filter out the unwanted frequencies. Afterwards there is a mixer to combine both humbucker halves into a whole. Signal 1 and 2 go to a mini-dip switch on the plastic casing.

Why am i doing all this work?
Personally i find that the wound strings don't match the plain strings perfectly. The bass strings sounds too often too dull. I'm not a rock star i don't change strings every week. Or month. A high mid/ treble boost will improve the sound of the bass strings but will make the treble strings sound nasal or thin.
Do some of you experience this kind of problem and if so what were your remedies? Or did you accept and learned to live with it. I haven't read much about this in fora at all. Perhaps this topic should be taken in a more general sense. How to deal with the sonic differences between bass and treble strings on a guitar.

Okay i'll give you some conclusions of the tests, for what it's worth.
For testing i used a alesis quadraverb for some overall treble boost into a headphone amp. No speaker simulation, no distortion.

best sounding results for eq on my Epiphone
filter out 500 Hz on the treble strings (Q=1.75 , -11 dB)

filter out 190 Hz on the bass strings (Q=1.0 , -15 dB)

the mini-dip switches
bass strings: the mini-dip doesn't seem to affect the sound of the strings ringing much but more the sound of the pick hitting the string. I cannot get it to sound like an acoustic. (Have you people tried bass strings for acoustics on an electric? I once did and i liked the thinner sound. Easier to get an AC/DC rhythm sound. The bass strings were lacking in volume but with split-in-half humbuckers that can be solved.) I like the mini-dip set at 3.4 Khz.
treble strings: 2kHz gives a typical humbucker sound, 3,4kHz gives strat brightness to cut through, 5kHz sounds a bit thin.
In the 2 kHz position bass and treble strings seem to be balanced best.

Cheers,
pp

[Deleted]

Man, my hat goes off to you, i admire your results, persistence and methodology. (you are also an open source user as i can see).

But, are we sometimes too obsessed with things that are only reproducible in "lab"-conditions? Did you take your epi to play on a full stack, did you try recording into the sound card, etc??? all those various extremes affect the tone much more than the pups.
I have managed to produce almost nu-metal tone out of the anemic Dimarzio HS-3 if that says smth.
In my ibby, i bought it new in September (twice, read on). The first one came with the tail piece (it was my first gibson-shaped guitar) damaged. Cause i hadnt realized this at the beginning, i tried almost all possible solutions to my horrible buzzing problems. Must have changed strings at least 5 times in 2 weeks. Nothing helped. Then i managed to return this guitar to the seller and get a new one with no such problems. Guess what, i play this axe since late September with *factory* strings. Ok, it has 1-2 slight problems, but i can live with this.

What i am saying here, is that it does not take to be a nuclear physisist to emulate AC/DC rythm tone. It is amazing that you have managed to do this, kudos goes to you, full respect, but in most cases just by "liking" a guitar, a player can sound so much better, even if his strings are old and rusted or his mid/treble/bass application does not spread evenly across the 6 strings.

Just my 2cents, and i repeat, you are aewsome!

[D2o]

I agree that he is awesome for buggering about with such an unusual project and I hope he continues to keep us abreast on his progress (hopefully even with sound samples at some point).

Cheers,
D2o

[perfboardpatcher]

Thanks greekdude and D2o for your comments,

Yes it's a bit of a fetish i have to go through so much trouble to even out the string response. Luckily i'm not the only one with a fetish on this forum. There are the squeeze out the last drop of sustain from your guitar, and the i want to have all possible pickup combinations fanatics. So I believe i'm in good company!

Okay i will try to explain what the kind of eq i'm looking for. I want to have a totally clean electric guitar sound without any effects to play along with any cd (blues, pop, metal, whatever). I've reached the conclusion that in order to achieve my goal i have to split my coils in half. I get your point greekdude that perhaps my guitar is not up to the task and it would be much wiser to use another guitar to achieve the same results with a lot less work.

Do not fear, i will continue with my work in one form or another. As a matter of fact, i've been working on some other diy pickup lately. I do it just for fun, don't make the mistake to take this all too seriously. And i haven't sold my stock pickups, i can always go back to them.

I'm afraid that my sound clips wouldn't blow you away unless I come up with a spectacular application. Sustainer perhaps? Just talking to myself.

cheers

[Deleted]

Since your primary aim is the clean tone, i guess we would be blown away by a clean clip, and then maybe a distorted one, demonstrating the lack of noise? oh wait!! personally i am blown away either way. I had tried to google some of your elements you mentioned in your OP, but with no so much luck. If you could give some theory behind it, and the current state market-wise of those components that would be great.

[JohnH]

All cool!

One thought I gave had about seperate coils for lower and upper strings is to then feed them through two seperate overdrive or distortion circuits. With the low bass signals kept out of the upper signal, it can sing more freely without being blocked by large bass waveforms. Even better would be two amps.

[perfboardpatcher]

The trafos i got were leftovers, anonymous wallflowers. I was lucky to get them for cheap. You need to search for audio mini transformers. Some at mouser.com look like mines. All Products >> Passive Components » Transformers Audio & Signal. The conversion from transformer into single string coil is a risky business, there's almost no margin. I had to file off the bobbins until the copper windings became visible. And I ruined a few coils.

Well, there is another way. You could position the bobbins slanted the way a strat bridge pickup is positioned. Your humbucker will become bigger than standard size.

Something like this:

N__S____
_N__S__
__ N__S_
_S__N__
__S__N_
___S__ N

Apart from dimensions you need to check the DC Resistance or impedance. If that's too low then there's a big chance there aren't enough turns of windings on the bobbins.
Okay I will do a sound clip but only after I've finished the split-in-half humbucker I'm building for my other guitar.

Indeed John, treat bass and treble strings as separate instruments! You and I are on the same wavelength.

[newey]

Indeed John, treat bass and treble strings as separate instruments! You and I are on the same wavelength.

Not the same thing as this "6 X 2" layout, of course, but the idea of treating the bass and treble strings differently brings to mind the Gretsch stereo White Falcon and Chet Atkins Country Gentlemen models.

These had 4-coil HBs, with 2 coils for the E-A-D and 2 for the G-B-E. Chet was rumored to have used these with the stereo output going through an echo unit for the bass strings into one amp, and then clean for the treble side into another amp. As said, treating it like two different instruments.

Neil Young plays one of the stereo White Falcons although I don't know if he uses the stereo option.

[perfboardpatcher]

Not the same thing as this "6 X 2" layout, of course, but the idea of treating the bass and treble strings differently brings to mind the Gretsch stereo White Falcon and Chet Atkins Country Gentlemen models.

Or as variation on the same theme have separate switching options for bass and treble like in the Italia Imola.

www.italiaguitars.com/new/guitar/imo.html

[CheshireCat]

Brilliant concept! Can't wait to see how it develops!

C.

[perfboardpatcher]

Thanks, CC! And you need to have some more patience...

I'm by no means done with this project. For the time being I have some other guitar lying on the operation table demanding my fullest attention. And taking more time than expected.
The goal of this operation is to install another different design split-in-half humbucker.
So it's kinda related.

[sumgai]

Mar 10, 2013 5:47:52 GMT -5 perfboardpatcher said:

Thanks, CC! And you need to have some more patience...

CheshireCat - more patience? I don't think so - just look at his profile... it's been "only" 4½ years since his last post!!!!

---

'Cat,

How'd that pickup-in-neck thing ever work out? 'patcher might wanna learn what've done there..... Just sayin', ya know.

Come on around more often, the NutzHouse misses ya! ;D




sumgai

[ourclarioncall]

Cool 😎

I had the idea of having a pickup for each string that could be slid to different positions

I’m sure a million other people have had the same idea lol

But has it been done ?

Think you get single coils that have different pole piece magnets for the top and bottom strings now , but that’s probably old news

[thetragichero]

ourclarioncall yup i have had the Duncan five two in the bridge of my tele (will be building a new body for it at some point) for almost a decade. honestly can't tell you if it's any different than a normal pickup lol