Category Archives: Guitar rig hookup options

Roland GA-112 Chassis replacement

I purchased a Roland GA-112 amp on eBay and it arrived with the chassis cracked on the right side. So I called Roland for a replacement side and they shipped me a new chassis, as its glued together into one piece! So after forgiving the cheat on eBay who sold me the cracked chassis while posting pictures of a pristine amp, I also forgave Roland for a poor design of the chassis – and not thinking of design for serviceability. WP_20160221_18_20_34_Pro

Above is the cracked right side of the chassis. If it had been designed as a replaceable part, it would be a matter of removing a few screws and taking it off, putting on the new one.


I started by taking a picture of the back of the GA-112 amp as I use two of these in my studio for left/right channels coming from my Roland VG-99 guitar synth. Basically, the outputs from there use the amps as just power amped cabinets, bypassing the front input which drives the amp circuit.


Above is the back removed from the amp chassis. Eight things have to be unwired to detach the entire board assembly completely. The plug on the left with the black and white wires, the nut holding the earthing wire, the three plugs on the upper right, starting from the two with red wires and the one immediately next to it (but not the last one on the right corner), as well as the small plug underneath the board on the upper right, which is seen between the second and third plugs, as well as one small plug with black and white wires in the middle of the lower board on the left. Also, remove the screw holding the cylindrical ceramic part around the power cable to the left.


After removing the screws for the front grill, remove the front orange cosmetic panel unscrewed using a matching allen key. Then remove the three retaining screws that hold the front amp circuit board in place.


Keep the amp upright and unscrew the eight speaker screws, reach in from the back of the amp and while holding the metal rim of the speaker firmly from the front, push the coil center gently with hand. The speaker will dislodge and drop out. Do not let it fall as it will land on the power amp at the bottom of the chassis!


Unclip the three leads from the back of the speaker. Note that blue one goes on top not the black one, when you reassemble.


Above on the right is the set of all disassembled screws and one flanged nut kept in batches – do not mix them or your reassembly time will be longer! Once the speaker, front and back panels are out, flip the amp over and unscrew the four screws to remove the power amp from the bottom of the chassis.


Make sure to untwist and retwist the black cable tie on the upper left of above photo after reattaching the plugs when rewiring the board after placing it into the new chassis.


Check out the USB port present on the mid-left! This is on the rear panel, and since its too far back from the rear panel, there is no hole in it to allow connecting to it from outside. I bet this allows USB recording at 44.1KHz/24-bit  or reprogramming of the amp COSM models. The manual does not mention it!


Make sure to keep cables clear of the boards by using the twist ties stapled on the inside of the chassis on both sides of the interior. This will prevent hum by keeping all cables close together and also prevent cables being subjected to conductive heating from the components on the board.


Power amp remounted on bottom of chassis. Four screws have to secure it from underneath. This is the high voltage components, and it is crucial to keep cables tied off using twisties onto the side of the chassis.


Reconnect the speaker using its wires as shown above: blue goes in the middle.


Reconnect the white plug and earthing wire with the nut.


Reconnect the power amp plugs back and tie off cables to chassis using stapled twisties inside.


Insert and screw front and back panels and mount the speaker, screw it back into chassis.


Secure cables using twisties to inside of chassis




10 Steps to build a Pro-grade EMG + Graphtech Acoustic-Electric-MIDI Stratocaster

Below is a parts list to build a pro grade Stratocaster MIDI guitar. Knock yourselves out making one! 🙂 Just go to each website and search for the part numbers below. The options for some parts can be chrome or gold, I have put down black parts. There are also two more colors available for the body – Cherry Burst and Blue Burst. The neck could be maple or rosewood, and you could pick a standard neck instead of a compound radius neck too. There are other prewired pickguards for strats available besides the Vince Gill one shown here on as well.

  1. Part 5751, Tobacco Burst Body $208.59
  2. Part 5713 Rosewood Compound Radius Neck $124
  3. Part 300267000000000 EMG VG20 Vince Gill Prewired  Pickguard $ 279
  4. Part PN-0080-B0 LB63 Bridge with Piezo Pickup Saddles +  Floyd Rose Black $315
  5. Part PK-0680-00 Ghost Complete Kit for Guitar (Acoustiphonic + Hexpander) $419.95
  6. LB63 Tremolo Arm for Floyd Rose $11.95
  7. Part  101539000000000 Elixir Nanoweb Electric Guitar medium strings $10.79
  8. Part 5460-B Steinberger Gearless Tuners Black $99.98
  9. Assemble the guitar (Priceless)
  10. Tune it (Priceless)

Total cost of this guitar: $1469.26. This guitar will surpass Roland Ready Strats ($1200) in tracking as the Graphtech MIDI system tracks much faster due to the piezo saddle pickup approach as opposed to the Roland GK-3 humbucker approach. This is the same MIDI/A/E system found in Carvin SH-575, 675 guitars, which sell for around $2000 – $3000 depending on extent of customization. Its tuning stability will be very high given the Steinberger gearless tuners, and so tremolo arm use will not throw it out of tune easily.

You will need a Roland GR-55 ($ 699) or VG-99 ($1599) to play it.

Roland 13-Pin connectors and MIDI over wireless not possible?

I have been wondering over the last three years why there is no 13-pin MIDI wireless capability to enable MIDI guitars to connect wirelessly to devices like the VG-99, GR-20, GR-55, GI-20 by Roland. I dug into this thanks to web searches all morning today as it’s a day off from work due to the flu.

One thing led to another and to another and before long, I discovered this detail posted here, regarding 13-pin connectors and their relationship to the guitar:


Please find below the pinout protocol for DIN-13 connectors.
Pin 1 = String 1
Pin 2 = String 2
Pin 3 = String 3
Pin 4 = String 4
Pin 5 = String 5
Pin 6 = String 6
Pin 7 = mono guitar signal
Pin 8 = synth volume
Pin 9 = no connection
Pin 10 = switch 1
Pin 11 = switch 2ut
Pin 12 = +7VDC power
Pin 13 = -7VDC power
Sleeve = Ground
4 3 2 1
8 7 6 5
12 11 10 9
The shell (sleeve) connection is Ground.
Here are a couple of Roland part numbers for DIN-13 jacks like those
found in the GR-50, VG-8, US-20 and GK-2. You can contact an authorized
Roland repair shop and get the replacement parts from them. These people
tend to respond better when spoken to softly and whispering valid part
numbers in their ears.
mfr p/n TCS5093-10-4152 – Roland P/N 00564556 – VG-8 & US-20
mfr p/n TCS5044-10-211 – Roland P/N 13429663 – GR-50
Best regards,


There are many 5-pin wireless MIDI devices out now, the stage standard being the MIDIJet Pro. But when we consider the 13-pin layout, Pins 12 & 13 carry the POWER which cannot go wireless. So we have a few design steps to get past before being able to build a wireless MIDI guitar:

a) Get a local power provision in the guitar itself, using the 9-V battery that powers active pickups and such.

b) Do a voltage step-down from 9V to 7V  in order to connect the +/- leads for pins 12, 13 directly to such a transformer output, then design a circuit that can convert the signals on pins 7,8,10 and 11 to wireless digital data and put it onboard the guitar.

c) Design software to capture the data stream for pins 7,8,10,11 on a computer that interprets the MIDI volume up/down continuous variation as well as the discretized MIDI change control (CC) commands.

d) Use the continuous MIDI data flowing from strings 1-6 over pins 1-6 using a one for one MIDI to wireless bluetooth 2.1 adapter (such as the one found here).

e) Ensure that all data from pins 1-11 are handled without different amounts of time-lag once received by the computer to pass into DAW software like Ableton Live .

I would really like a custom wireless MIDI guitar design that has a software/hardware match with realtime playing capabilities.

My new studio schematic

Download PDF of schematic here.

I have been slogging silently over the past few weeks to figure out the setup of my home studio that will establish it for anything I need to do using MIDI and guitar coupled to my audio computer applications. I am fortunate to have won auctions on eBay for a Roland VG-99 and FC300 MIDI pedalboard during September. I have been playing with the VG-99 over the last week and have had some truly astounding insights into the design and applicability of this “virtual guitar system”.

Below is my first attempt at designing a new schematic for integrating the VG-99 into my current studio after removing the BOSS GT-8 guitar multi-effect processor from the equation. I will tweak it a bit once the FC300 arrives and I have a chance to play with it.

The requirements for the development of this schematic were deep yet straightforward:

  1. Enable Ableton Live, EZDrummer and EMulator X3 into live playing situations via computer integration into the setup.
  2. Connect VG-99 with GR-20 to be able to play either or both from a single MIDI enabled guitar.
  3. Simplify recording from guitar, VG-99, GR-20, keyboard triggered MIDI synths in Ableton or Emulator X3 as well as EZDrummer Pro.
  4. Enable single location driven amp channel switching and two amp based live sound.
  5. Enable backing track play from computer audio or from external feeds such as MP3 player, Tascam Guitar practice devices.

With this in mind, I set about designing this schematic from scratch this evening, and six hours later, I have it! Click on the image below to see a larger view or download the PDF from the link on top.

Rajiv's studio schematic

Self installation notes: MIDI upgrade using Roland GK-3 on Epiphone Black Beauty & acoustic-electric upgrade using LR Baggs M1A pickup on Silvertone PD-2 dreadnought

I installed a Roland GK-3 MIDI pickup on my Epiphone Black Beauty last year in October in a matter of two hours. The below notes are as much to help me remember for the next time I do this sort of thing as to help anyone who wants to save megabucks getting a guitar tech to do this for them. Here is how I did it:

0) Very important step: intonate your guitar by adjusting the bridge screws using the same guage strings as you will be putting on the guitar after installing the GK-3 as once it’s installed, intonation screws are not accessible due to the GK-3 hex pickups location.

1) Unstring the guitar completely while keeping it flat with top up (to prevent bridge stop bar from falling out when unstringed, do not pick up guitar once it is unstringed)

2) Install the GK-3 pickup under the bridge using the LP mount template the GK-3 comes with – it matches the bridge shape amazingly well and does not dampen the bridge noticably. As such, the Epiphone Black Beauty has enormous sustain due to all mahogany non-chambered construction (it’s a heavy guitar for a reason). So installing the GK-3 does not impact it’s sustain even for blues lead playing.

3) Restring the guitar starting with the 6th string and tune up to std. tuning. (EADgbe)

4) Adjust the GK-3 hex pickup gap from each string using the steel gage that comes with the GK-3 kit, and using the side mount screws for the GK-3 onto the mounting plate attached to the bridge. Make sure the distance is accurate for EACH string or pickup sensitivity will not be uniform for uniform string-picking intensity!

4) Attach the 13-pin plug from the GR-20 cord to the GK3 anf attache the 1/4″ short cable to the GK-3 and guitar out jacks.

5) Calibrate the sensitivity on the GR-20 for each string by adjusting the GK-3 flexion screw (verrrry tiny screw in the middle of the hex-pickup row on top) using the verrrry tiny screw drive that comes with the GK-3 kit.

The final installation looks like this:


See how the intonation screws on the bridge are blocked? Make sure you intonate the guitar BEFORE installing the GK-3 hex pickup using the same gauge strings as you will use after installing GK-3 to be as close to the perfect intonation as possible!


This thing rips blues notes and plays any MIDI instrument simultaneously now via the GR-20. (See my wiring diagram blog entry on this site to hookup the RC-50, GR-20, GT-8 and play!


I also installed an active magnetic humbucker pickup by LR Baggs, model M1A on my Silvertone PD-2 Dreadnought on 2/26/2009. Below are some pointers and interesting observations in doing so:

1) Drill a 1/2″ hole on the strap mount at the bottom of the guitar after removing the strap mount. Take the1/4″ connector and make sure it fits loosely into the hole you just drilled. If it is tight, use sand paper to finish the inside of the hole to smooth it out after running the 1/2″ drill at a slight angle and rotating it so there is a dual funnel shape ,making the hole slightly larger than 1/2″.This will allow pulling the connector from the INSIDE of the guitar easily and mounting it later.

2) Blow out any debris from inside the guitar using a hair dryer on cold setting.

3) Take an old E string and send it in through the hole using the non-balled end from the outside and grab it from the 6th string side of the soundhole.

4) Remove the end nut and washer from the thin part of the 1/4″ connector that comes with the M1A pickup.

4) Insert the string tip into the two end pin holes of the 1/4″ jack connector that comes with the M1A pickup. Twist it into a loop. Pull it out after wrapping the ball end of the string on your gloved hand. (If you don’t use a glove, you won’t like how it cuts into your wrist when you pull the connector through the end block of the bottom of the guitar).

5) When the connector is pulled through, it will have the narrow portion of the tip visible, and the washers on the other side will prevent it from coming through. This is the tricky part as you have to put on the outer washer and nut but there is a loop of the string you used to pull it through in the way!

6) Take a small screw driver and put the nut and washer in that order on it then insert the screwdriver tip into into the one of the holes in the connector and push it down into the side of the end block to retain the connector in its position. BUT DO NOT insert the screw driver from the side, insert it from the top and center, and hold it while you untwist the string loop and remove the string.

7) Put down the outer washer onto the tip of the connector as well as the nut and screw it onto the connector tip. Remove the screw driver and use a spanner to tighten the outer nut and also screw on the strapjack button that comes with the M1A pickup. Tighten this as well, using a spanner.

8) Grab the 1/8″ connector cable from within the soundhole of the guitar for the pickup to connect to it and insert it into the side of the pickup while holding the pickup carefully.

9) Loosen the side mounting screws on the pickup to open up a gap between the top and the bottom of the pickup. Insert the pickup sideways gingerly past the 6th string and bring up one of the top edges over the soundhole, then twist the pickup to bring up the opposite side on top of the soundhole. Tighten both side screws and you pickup is mounted! Make sure the pole pieces of each string are aligned so each string passes exactly in the middle of each pole piece of the pickup.

LRBaggs on Silvertone PD-2

10) Hookup a 1/4″ cable to the strapjack you just finished working on into the LR Baggs Para acoustic DI or directly into an amp. The M1A is an active pickup and is humbucker style, so it does not need a preamp unless you need to equalize and cancel further hum by using the notch filters on the Para Acoustic DI. You can hookup directly to an amp as see if the sound is to your satisfaction or play with it now!

My Recording Studio Wiring Setup

Rajiv's Recording Studio Wiring Setup

I use this setup very effectively for live performance as well as studio recording by leaving behind the EMu 1616M, the Philips surround sound system when going out for live performance. To download this in OneNote, PDF or Single HTML File (MHT) format, look in the Public folder on the left. These files can be viewed at 100% resolution to see all details of input output connections. Also, if you are wondering why Philips for my studio monitoring system – I happened to have this lying around and put it to good use instead of buying studio monitors although I have my eye on Behringer or EMu monitors eventually. This setup cost roughly $4500 for mastering grade recording capability, using some of the world’s best recorded sound banks from EMu. Similar setups cost in excess of $40000 using ProTools and DigiDesign equipment from what I hear!

I have seriously good sound creation capability that can be recorded digitally at 24 bits from 44.1KHz upto 192 KHz using the same mastering grade DA converters used by DigiDesign in professional studios at a tenth of the cost. Now I have established a way to keep practicing using the numerous books I am struggling to form a practice curriculum from. My journey has begun and its awesome seeing the results emerge!