DIY Hex Pickup Project

[4real]

Excellent John, and thanks for that encouragement on that idea, I think there is some merit in the concept though perhaps not the best person to follow through on all the details as to how one might make that kind of thing happen.

I ahd always perhaps suspected that there may well be 'jumps in volumes' and such with selectable pickups and my application. I am not sure that there is an easy functional way to make this happen (Likely the use of switches such as I have done perhaps not possible and other types to bulky and impractical perhaps).

However, others perhaps have ideas for things to be six individual outs and perhaps this is a way to approach things in some ways and to use such an idea that a few people have raised as potential problems and certainly short falls with other kinds of approaches to hex pickups, especially the more bulky and conventional coiled designs.

Regardless, the achievement so far is that I was able to successfully get a decent signal out of this novel and compact design and that is itself something and a good start in many ways.

There may well be ways that the design can be altered to give better separation in of itself.

The phase thing, well, I am glad you were able to pick up on my general thoughts and give that some more form and strategy, I will give it some more thought though nothing has jumped out at me to make it immediately functional...a rough thought is to take everything directly out and run them through individual preamps, perhaps even using something like this www.jaycar.com.au/images_uploaded/CD4050BC.PDF within one chip...unless I am being a little too naive with that thought.

There is also a completely different kind of approach I have in mind and will do a little 'tinkering' on that idea in the very near future and there are a range of interesting and novel and potentially more miniaturization and intrinsic separation in that approach if it works.

Ok, time to sleep on those things some more, but many thanks on that, very helpful encouragement ~ p

[4real]

Just a bump on this

Did some very basic preliminary tests on a different approach to this question and confirmed that I can get a good, very quite, very compact and completely separate signal from strings and a decent sound too if a bit neutral.

These things take time and patience of course, but at least this is a promising start and have lost none of my enthusiasm for such a device.

I am considering, if things go ok with this approach, to go towards a stereo version...so the switches will decide which channel they will go to. With a mono lead one should get just one channels strings so achieving the most basic first version regardless but also test the ability for this to perhaps be the sole pickup on an instrument.

While I am still wanting to add this to my recent gutiar, I ahve hopes for a new instrument in the future based on that and this pickup concept. I can also see the application in particular on acoustic guitars so that too will be something I wish to explore and this system promises to be small enough in the sensor to fit on a flat top...

well, early days of course, but still working on it... pete

[gtrdrumsplayerduarte]

Hi from Portugal.

Let me start to congratulate you for exposing in detail this idea.



I`ve put mine to work. The thing I needed was to isolate the 5 and 6 string, so I could feed it to an octave pedal and create a "Virtual Bass" out of it. Then create basslines while playing acoustic guitar.



I bought the cheapest cassete adapter at the chinese store for 1,5 euros each. Bought 4 units.



First I used a magnet for an old pickup for a squier guitar. Then I bought very small but powerfull magnets at rs electronics online. They are smaler than the tape heads. The pickups are wired in series and separated to the distance between strings.



For preamp I used a small 4 channel line mixer from behringer I had around. It`s set a ten But still I get a preatty clean signal.



After the mixer it goes to the octave pedal.



I had to put the pickup at neck position. In bridge position the pickup would pickup even the ressonance harmonics from other strings and trigger "false" notes on the octaver.



Now I will be trying to put everything neat and built for life



I`ll take some pictures as I do that.

[4real]

Hi there gtrdrumsplayerduarte

I played with all kinds of things and did get a signal out of the tape head things, takingthe inspiration from old roland synth hex pups, but was not happy in the end with the results I was able to achieve with the kind of heads and such that I could get cheaply ~

In the end, I did make even smaller pups myself for the low %th and 6th strings. They work together like a mini humbucker pair across those two strings and the magnet such that they are attracted to each other and so barely picks up the adjacent 4th string.

They are very low impedance, but are amplified by a preamp in the guitar and give an extremely clean signal.

So, designed for exactly this purpose, to produce a separate signal for the low E and A strings and would require a 'pitch shifter pedal' not and ocataver or similar that will 'glitch' if it hears more than one note at a time. Thee is a behringer pedal that can do that and one by Boss for a lot more, or good pitch shifting pedals. The normal pickups also pick up these strings, so the low notes give a doubled low octave to it.

The guitar has a short entry in the Gallery here...

guitarnuts2.proboards.com/thread/6970/strat-multi-tuning-piezo-electric

And a very long build thread that explored all manner of spects that went into the guitar here...

guitarnuts2.proboards.com/thread/5970

The end result looked like this...



Compared to the tape head idea and several other things I tried, these were the most successful at easily and cheaply and compact enough to achieve the results I was experiementing with...

...

Some inspiration for this comes from guitar player 'Steven King' who has a pickup for the low two strings and uses an octave pedal...



Steven king originally used a strat like pup inside the guitar runnning along the E and A strings I believe. He used/uses an octaver pedal prefering that sound and just makes sure he does not hit both strings at a time...

I've kind of moved on from this concept into altered and lower tunings, often down as low as C (such as CGDGBE) and you'd likely not want to go too much lower anyway.

The tread for my current project can be found here...

guitarnuts2.proboards.com/thread/6883/godin-seagull-maritime-modifications

Takeing a conventional acoustic and things I learned from the 'jazz trat' thing, I am moving towards actually tuning the string down, facilitated by a 'braced top' and very accurat locking tuners.

The idea though still has a lot of merit, for all kinds of reason, not just the octave down thing, but running perhaps different effect chains on different strings for instance. There are people working in this direction, but it can get unweildy and don't really think that the tape head thing is going to cut if for that kind of effect anyway. It is still something to aim for and who knows, I might return to the concept in time ~

All the very best of luck with it, pete

[daveg]

All your hard work encouraged me to set to with a powergig hex pickup on a £15 Encore (Strat copy) from a carboot sale.
Started gouging out space for it to replace the bridge pickup then had an intuition that I should experiment placing it at the neck and middle position. (I'm new to this) I salvaged the curved plastic lid that hides the front headphone and usb sockets on an old DELL pc, that perfectly suited to act as a temporary testing rig. This I cut a rectangular hole in to hold the PG hex pickup (inverted) close or far from the strings. Bits of doublesided sticky tape raised the temporary pickup holder and helped keep the pickup still while strumming strings.
 Having found the fullest frequency range is near the neck and really nice clean, crosstalking signal, next I'll enlarge the present pickup slot with a router to make room for the 7 screened cables. The cables all end in plugs that fit an old hard drive data socket, so that will all go in the bridge pickup slot and run a multicore screened cable to an 8-pin din s-video socket. Next the 8 wire+screen cable will go to a breakout box for pickup phase and stereo switching. Thinking of strings 1,2,3 - left ch. and 4,5,6 - right ch. Then we can have strings 1,3,5 -left ch. 2,4,6 -right ch. Adjacent strings like 1,2 can be 'humbucked' by all odd strings being phase reversed, etc , etc. Other ideas and experiments will surely create good sounds, like a 4 channel (14W per) surround sound amp and 4 speakers....  

[newey]

daveg-

Hello and Welcome to G-Nutz2!

You have submitted a first post that a) doesn't ask a question, but updates an in-the-works project, and b), a post that follows a coherent test strategy- the test mule idea is a good one for this sort of experimentation. So, Bravo!, and you are now officially Nutz™

Unfortunately, 4real hasn't been around much of late, so not much chance of further info from him on this type of project.

[daveg]

I found another forum also didn't follow through with the PowerGig hex pickup, but I liked the tone of the single and the hex coils on my old Encore body. Guess its the cheap plywood body resonates nicely with the PG pickup....? The hex coils are about 815 ohms each and the single coil 10.2k. If anyone finds a PG guitar this hex pickup saves a lot of work but the crosstalk from adjacent strings may put people off. I'm guessing that with adjacent strings switched to opposite stereo channels the crosstalk may help spread the stereo image.

[bbsailor]

There is another method to make a hex pickup. Use the metal strings as a moving coil pickup. Web search "moving coil pickup for the technically curious" or try this.

Here is the initial test to do a quick experiment. Obtain one (to test) or six (to install in guitar) small audio transformer with an 8 ohm side and a 10K to 50K side. Use it as a step up transformer with the 8 ohm side alligator clipped across one string behind the nut and the bridge.

Attach the high impedance side of the transformer to the amp input. 

Hand hold a magnet near the plucked string and listen!

The moving metal string is inducing a voltage of about 1 to 2 milli-volts (mv) that is being boosted by the turns ratio of the transformer. If you use an 8 ohm to 20K transformer the turns ratio is calculated this way. Divide 20K by 8 and get 2500. Now, take the square root of 2500 and get 50. The turns ratio of this transformer will boost the input voltage by about 50 to get a usable output between 50 mv and 100 mv.  

Now the challenge is to get a good low resistance ground return from the nut side of the guitar that is at least 10X lower resistance than the lowest resistance guitar string to minimize resistance losses on the input to the transformer. One clever method is to use the truss rod as a ground return or a copper strip under the fingerboard extended into the guitar body connected to a brass nut for the common ground connection for the six transformers. now use the string connection behind the bridge as the hot input source to each transformer to have total isolation between strings.  This acts like a six channel ribbon microphone. locating different length magnets along different places on the string will provide audible level and tonal differences in the output. The longer the magnetic fileds on each string will alter the output; longer provides higher output.

I uses an 8 pin microphone connector on the guitar with a six conductor shielded cable and split off the amp end into six .25 inch guitar plugs, one per string, that I could input to a six channel mic mixer and control each string independently.

I hope this provides another way to independently pickup guitar strings? 

Joseph J. Rogowski

[JohnH]

Hi Joseph, welcome to GN2 and thanks for your ideas. Please keep having them!

I also tried that, just to see if it works, and it does in principle! I used a mic input on a mixer.

But to make a working system, there are a few more challenges IMO. One of them is how to electrically isolate each string. You can have one and as a common connection (eg, metal nut), but the other end needs to be separated, so separate or isolated bridges are needed (or a non-metalix bridge, as on an acoustic?). Also, as strings get fretted onto metal frets, strings touching the same fret have their signal path changed by the connection of more strings, and I heard jumps in volume. But it sounds like you have a working system. Did you find that these were issues in practice?

EDIT: Thinking more, I could believe that if the nut end is the common ground, the transformers/preamps have significantly higher impedance than string resistance, and we are talking about an acoustic-type non-metallic bridge, the it can be all good!)

[bbsailor]

Sorry for the late reply. My ideas typically do not get a lot of positive responses.

Look at it this way. The common ground is the nut. That common ground is returned to the guitar body through the truss rod or some other creative way that is ten times lower in resistance than a guitar string resistance to minimize input matching losses. Now, all the outputs from each string come from behind the bridge which should not be conductive. Seek non conductive bridge inserts. Then, attach the output from each string to the primary of the transformer (8 ohms or 4 ohms) and the common ground from the nut. Then, connect the output of each transformer (10K ohm side up to 20 K ohm side or higher) to the 7 or 8 pin output connector. 

Now, each string acts like an individual ribbon of a ribbon microphone when the magnets are put under the strings.

This technique will allow individual string outputs with no cross-talk between strings.

Joseph J. Rogowski