And then the fight began . . .

[kingkorg]

I must admit I don't really understand how these coils are connected. Are you willing to post a schemo?
The impedance of each coil is quite low, and so probably the output level. How is noise?

This is the simplest schematic

http://www.marksmart.net/gearhack/gr300/analogmods/gk2gr300interface/GK2GR300InterfaceHalf.jpg
Attached full GK3 schematic.

The original pickup has 6 humbucking coils of ca.100 ohm with 6 magnets. Mine DIY version worked just as nice without humbucking coils. Each string gets it's own output.

They are used with various Roland processors that process each individual string in different ways, emulations, synth, midi... Some people mod them to get 6 jack outputs and go into audio interface. Each string can be processed individually.

There is some gain provided by the opamps, as the coils are in close proximity to the opamps not much noise is added.

"Guitar in" in GK3 schematic is for additional input from existing guitar pickups that can be blended with the 6 "divided pickup" signals.

 

[kingkorg]

Here's a video i made a while ago demonstrating various guitar emulations going straight to amp. No effects besides modeling used on the unit. Keyboard is my first instrument, so no virtuosity in the video. The pickup picks up full range audio and applies IRs and doubles/phase shifts signal for strat tones for example... No audio is coming from guitar's pickups in the video.

A bit of a hijack, but i suggested in the original post just wiring all the coils in series > opamp with some gain = pretty much full range output depending on coils used. I don't think humbucking is necessary for clean sounds.

 

[Tubetec]

I remember one guy I knew got a piezo brigde conversion kit for the Les Paul , each saddle had its own individual output back to a processor inside the body , it was able to model acoustic guitar tones fairly well and blend it back with the main signal .

Thanks for the demo , Its hard to tell an emulation from the real thing , I think some of the newer Roland synths use 192k sample rates , any time stretch/ pitch changing is handled with a noticable smoothness , same can be said for any of the other internal effects that can be applied to samples .

I was kind of interested in what the actual audio output into a regular instrument input sounded like , did you happen to try that at any point ?

 

[mhelin]

Any traction? Thanks in advance for any suggestions that would connect my guitar with my amp and sound good. James

Try K&K Pure Mini (Western) pickups with an external preamp followed by an IR loader (some info here: Acoustic IR, also 3 sigma audio sells some good IR's: Acoustic Guitar Impulses - 3 Sigma Audio). Next step would be using a SDC clamped to guitar body and mixing the the signals of the two systems (assuming you are looking for an acoustic guitar sound).

 

[kingkorg]

I was kind of interested in what the actual audio output into a regular instrument input sounded like , did you happen to try that at any point ?

Worked like a charm!

 

[jeremynothman]

I will have to try that, but I am concerned about feedback and the inherent inconvenience of a mic stand crowding me. I am contemplating playing, not recording. Having to sit in one place to assure consistent pick up would be very difficult for me. Sitting still is not one of my strong suits.

I suppose "small omni" means omnidirectional dynamic microphone. The amp has a dedicated XLR mic input without phantom power. Not a DIY solution and I would have to buy something because my dynamics are all cardiod pattern, and I believe I previously mentioned I am seriously frugal (i.e., cheap) - n'est c e pas?



Ahem ... Objection, Your Orneriness. Asked and answered by previous testimony - additional testimony is merely cumulative.

Changing the end pin would require permanent modification of the instrument. Perhaps you missed my previous posts wherein I expressly announced concern over tape on the finish of a limited edition instrument, and not wanting to drill out the hole for a jack-type end pin. James

Apologies. I saw the wish not to modify, I thought that double sided tape internally wouldn’t be a problem.

I essentially mean an Omni lav mic mounted internally with double-sided tape, and I certainly mean a condenser, as I want it to have transient.
Yes, feedback is something of a challenge, but that is why they are often used in tandem with a piezo.

Anyway, the whole 0 modification thing makes this obviously challenging. Another option could be the kind of mount used by some drum-clip mics (such as the beyerdynamic TG-D58), mounted to the body somewhere near the neck join. Obviously less aesthetic and more potential for damage though given there will be clamping force

 

[JeffKall]

Good Day DIY Mavens and wizards. Let us stipulate I have a lovely limited edition Martin HD-28v acoustic guitar with one-in-a-million tone. (I played a LOT of 'em before selecting one that sounds better than the rest.) Let us further stipulate I want to play it through my Fender Acoustasonic amplifier (no debates about the amp, please, as it was a gift from my lovely young bride ... and while I have survived sitting in live sets on 6th Street in Austin, Texas, I am NOT a professional.) Also stipulate I refuse to drill any holes in my instrument. Moreover, I am am extrremely frugal (i.e., cheap) and like to build ham radio and audio accessories with a moderate skill level. Shoot, even though I designed a couple of really simple circuits that got published in a major hobby magazine, and twice won an antenna design contest, I remain a mere novice, so please go easy on me. (I have more ambition than skill.)

I KNOW there are LOADS of commercially available microphones, pickups, and combinations available, and yet, I wish to make or assemble a simple, straightforward microphone or pickup on the cheap that would sound good with my amp and not nick or scratch my instrument.

Any traction? Thanks in advance for any suggestions that would connect my guitar with my amp and sound good. James

Quite the conundrum, James … but it is virtually impossible to accomplish your end goal without concession !

Your post convincing demonstrates your primary goal to protect your Martin … so you are obviously constrained to eliminate ANYTHING that “attaches” to it in ANY manner …

I am not particularly impressed with piezo or magnetic pickups … for the same reasons both kingkorg and abbey road correctly stated … since neither delivers the true full range character of a refined acoustic instrument such as a Martin …

This leaves you anchored to a reasonably high end microphone on its own stand or attached to your vocal microphone stand (if you sing, too) …

I would caution against using an omnidirectional microphone of any type due to spurious unwanted sound pickup …

The ATM350 attached to your vocal microphone stand and pointed in the vicinity of the 12th fret would probably represent the best sounding solution (of those offered here) … given your determination to rightly protect your Martin …

Since there is no “have your cake and eat it, too” solution … anchoring yourself to a detached microphone that will deliver the best sound of your prized Martin would appear to be your best “cake” option …

As for the DIY factor … you could always build your own C12, M49, U47 or U67 clone (can you tell I prefer tubes on acoustic guitars ?) or any of the other excellent DIY offerings (dynamic or condenser) available here …

e.g. … My Apex 460 with DIY Fox Mini Mod recording of a Tacoma acoustic guitar with a touch of verb and no EQ:

https://www.dropbox.com/scl/fi/913o...iMod.wav?rlkey=f7ekp0m2kvn2fxswf56iqjuuy&dl=0
Best Regards !!!

 

[MicMaven]

Apologies. I saw the wish not to modify,

I essentially mean an Omni lav mic mounted internally

Anyway, the whole 0 modification thing makes this obviously challenging.

Good Morning, Mr. @jeremynothman - No worries and no apologies required - YEP - we are now on the same page. Thanks for weighing in. JHR

 

[ach]

followed by an IR loader

If the purpose of the pickup is to have a good live acoustic guitar sound that is in the mix with a band, or simply quick and bulletproof for gigs - and not to have a perfect recorded tone - then a decent piezo pickup with an appropriate IR is the answer. It is what the industry uses. Sites like Worship Tutorial (a lot of this work comes from church bands...) have IR's that are pre mixed for specific instruments and pickups, including high end martins. Impulse response convolutions are linear functions, so can even be further mixed/EQ'd using any DAW to tweak your own sound. You'll have a single guitar pedal to quickly plug into on stage and have consistently good tone.

 

[MicMaven]

Quite the conundrum, James … but it is virtually impossible to accomplish your end goal without concession !

Since there is no “have your cake and eat it, too” solution … anchoring yourself to a detached microphone that will deliver the best sound of your prized Martin would appear to be your best “cake” option …

As for the DIY factor … you could always build your own

Geeze, Louise. You get it. Good closing argument and summation, Counselor. The bit about trade-offs and concessions strikes a chord.

The low cost DIY requirement is because that is what we do here and it is fun to make stuff. Money is not an object, as I can easily afford a commercially available pickup solution and those suggested over the weekend look very good (although I have no interst in computer modeling apps - why model a D28, if I am playing one? And, if I wanted it to sound like a Gibson or Taylor, I would just buy one of those.) And, I realize I may have to pry open my stainless steel wallet and get something that mounts on the instrument and sounds as it should. It may come to that.

And yet, while the your summation is spot on, perhaps the situation may not be as dire or as absolute as that.

As you suggest, some concession may be necessary. I sometimes contemplate inventing some sort of simple clip that would put a microphone element in or near the sound hole, which is so simple and clever it cannot mar or scuff the finish, while placing the mic element where it is effective.

I imagine a narrow U-shape "thing" that slides over the top around the sound hole and holds a small mic capsule/cartridge. It is lined with very soft felt or (better) a bit of thick, soft flannel cut from a favorite old shirt worn for decades. It does not pinch too hard. It has a very thin Mogami lavalier mic cable loosely leading to a powersupply/matching network - or maybe a small dynamic cartridge cannibalized from a good broadcast headset (like my Audio-Technica BPHS1 on my transceiver) and the cable is provided some sort of strain relieve, perhaps with a clip or other grip "thing" somewhere along the way sorta,kinda like some guys run guitar cables through the strap above the lower bout end pin.) The mounting clip "thing" must be very soft and almost loose, so it cannot scuff the top, yet effectively hold the mic element in place. The mic element might be placed in the sound hole, or or close to it, the way headset microphones sit off the the corner of the mouth to avoid plosives and heavy breathing into the element.​

I do not yet know how far an electret element can be from its power supply /matching network and be immune from EMI and RFI, but maybe it would be long enough to give some wiggle room - (did I mention I cannot sit still?) I concede this is tantamount to using the Primo or ATM microphones suggested earlier in the thread - the only significant difference would be how it is powered and matched to the amplifier - but if the cable could be long enough, perhaps that obviates that particular worry, as it would be placed at the amp end of the cable.

The conundrum, therefore, may boil down to picking a sensible mic element, and devising a suitable matching network to the amp, which has both TS instrument and XLR mic inputs, lacking phantom power.

I wonder if anyh of this rambling makes sense. If not, I suppose I will go shopping for the least dangerous, best sounding commercial solution.

In any case, I APPRECIATE the varied solutions proffered and discussed by others in this thread. Some stuff I would not have conjured up on my own. As a local electronics engineer (friend) says, "It's all good." James

 

[k brown]

Some have had success with a Sony ECM-50 (or similar; a more modern equivilent will have better RF protection) BluTack'd or taped to the inside.

Omni means no proximity effect to compensate for, and inside the body protects well from feedback.

 

[MicMaven]

If the purpose of the pickup is to have a good live acoustic guitar sound that is in the mix with a band, or simply quick and bulletproof for gigs - and not to have a perfect recorded tone - then a decent piezo pickup with an appropriate IR is the answer. It is what the industry uses. Sites like Worship Tutorial (a lot of this work comes from church bands...) have IR's that are pre mixed for specific instruments and pickups, including high end martins. Impulse response convolutions are linear functions, so can even be further mixed/EQ'd using any DAW to tweak your own sound. You'll have a single guitar pedal to quickly plug into on stage and have consistently good tone.

I appreciate the direct, unequivocal advice. While I occasionally play with other guys, I usually just play alone or imagine I am in whatever band is playing on the big stereo in the rec room. I might like playing in a church or bluegrass ensemble, but at the young age of 68 going on 75, that is unlikely. However, you describe my brother-in-law, although he plays Taylor guitars, and I play Martins and there is similar disparity betweenus concerning most every other little thing.

Maybe someday I will make the big time! THANKS for the suggestions. James

Gratuitous HISTORICAL SIDEBAR -
Fortunately, I was summarily dismissed from a garage band around 1969 because my hair was too short, I did not smoke anything, and had good grades; a bona fide nerdnik. But they did ME the favor, as it led me to a lucrative career in a very different field. But then, maybe there is still time for me to make the big time. JHR

 

[JeffKall]

Geeze, Louise. You get it. Good closing argument and summation, Counselor. The bit about trade-offs and concessions strikes a chord.

The low cost DIY requirement is because that is what we do here and it is fun to make stuff. Money is not an object, as I can easily afford a commercially available pickup solution and those suggested over the weekend look very good (although I have no interst in computer modeling apps - why model a D28, if I am playing one? And, if I wanted it to sound like a Gibson or Taylor, I would just buy one of those.) And, I realize I may have to pry open my stainless steel wallet and get something that mounts on the instrument and sounds as it should. It may come to that.

And yet, while the your summation is spot on, perhaps the situation may not be as dire or as absolute as that.

As you suggest, some concession may be necessary. I sometimes contemplate inventing some sort of simple clip that would put a microphone element in or near the sound hole, which is so simple and clever it cannot mar or scuff the finish, while placing the mic element where it is effective.

I imagine a narrow U-shape "thing" that slides over the top around the sound hole and holds a small mic capsule/cartridge. It is lined with very soft felt or (better) a bit of thick, soft flannel cut from a favorite old shirt worn for decades. It does not pinch too hard. It has a very thin Mogami lavalier mic cable loosely leading to a powersupply/matching network - or maybe a small dynamic cartridge cannibalized from a good broadcast headset (like my Audio-Technica BPHS1 on my transceiver) and the cable is provided some sort of strain relieve, perhaps with a clip or other grip "thing" somewhere along the way sorta,kinda like some guys run guitar cables through the strap above the lower bout end pin.) The mounting clip "thing" must be very soft and almost loose, so it cannot scuff the top, yet effectively hold the mic element in place. The mic element might be placed in the sound hole, or or close to it, the way headset microphones sit off the the corner of the mouth to avoid plosives and heavy breathing into the element.​

I do not yet know how far an electret element can be from its power supply /matching network and be immune from EMI and RFI, but maybe it would be long enough to give some wiggle room - (did I mention I cannot sit still?) I concede this is tantamount to using the Primo or ATM microphones suggested earlier in the thread - the only significant difference would be how it is powered and matched to the amplifier - but if the cable could be long enough, perhaps that obviates that particular worry, as it would be placed at the amp end of the cable.

The conundrum, therefore, may boil down to picking a sensible mic element, and devising a suitable matching network to the amp, which has both TS instrument and XLR mic inputs, lacking phantom power.

I wonder if anyh of this rambling makes sense. If not, I suppose I will go shopping for the least dangerous, best sounding commercial solution.

In any case, I APPRECIATE the varied solutions proffered and discussed by others in this thread. Some stuff I would not have conjured up on my own. As a local electronics engineer (friend) says, "It's all good." James

Thank you, James … for your kind response !

IF you are amenable to a heavily padded (go flannel !) clip in your Martin’s sound hole … then seriously consider the ATM350 … as abbey road suggested …

It is the most “off the shelf” RF-immune system (as k brown noted) … and there is no denying how good (dare I say “natural”) James Taylor’s guitar sounds in concert …

Best of luck in your quest !!!

 

[MidnightArrakis]

This is the simplest schematic

http://www.marksmart.net/gearhack/gr300/analogmods/gk2gr300interface/GK2GR300InterfaceHalf.jpg

Here's an update to the hand-drawn schematic that you have provided (P.S. -- Attached PDF files look much better!!!):



YOU'RE WELCOME!!!

/

 

[abbey road d enfer]

This is the simplest schematic

http://www.marksmart.net/gearhack/gr300/analogmods/gk2gr300interface/GK2GR300InterfaceHalf.jpg

I don't understand the need for ajustable voltage regulation, since it powers opamps, which can accomodate large variations.
Maybe there's another reason, but I fail to see it.

 

[Matador]

Maybe there's another reason, but I fail to see it.

It's odd: signal flow appears to be from left to right, however the bipolar 18V supplies appear to come from the right (that powers everything), then send bipolar 7V supplies back to the left.

 

[abbey road d enfer]

It's odd: signal flow appears to be from left to right, however the bipolar 18V supplies appear to come from the right (that powers everything), then send bipolar 7V supplies back to the left.

Yes, I noted that, but it still doesn't explain why (and if) the circuit needs to be powered with such accurate voltages.
On some versions, there is an on-board regulator that sends calibrated voltages for switching control, however this regulator seems to be pretty ordinary, and is not adjustable.

 

[kingkorg]

Yes, I noted that, but it still doesn't explain why (and if) the circuit needs to be powered with such accurate voltages.
On some versions, there is an on-board regulator that sends calibrated voltages for switching control, however this regulator seems to be pretty ordinary, and is not adjustable.

It's odd: signal flow appears to be from left to right, however the bipolar 18V supplies appear to come from the right (that powers everything), then send bipolar 7V supplies back to the left.

It's been a while since i built this project, IIRC those are control voltages for volume control (maybe even two switches) which are sent to processor unit. That volume control can be assigned to various parameters. I believe it's shown in GK3 schematic.

 

[MidnightArrakis]

DON'T SHOOT ME!!! I'M ONLY THE MESSENGER!!!

/

 

[abbey road d enfer]

DON'T SHOOT ME!!! I'M ONLY THE MESSENGER!!!

/

Has anybody shot at you? I don't see it...