PRIMOVA - GKMX-33 Project - The ultimate-No US-20 bug 3in/3out GK switcher

Started by CodeSmart, March 25, 2014, 12:50:21 PM

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CodeSmart



Got my my mind occupied about a new next-gen microcontrolled GK-switcher.
What do you think guys?  :P

GKMX-33 Specification idea
================================================
- Selection of 1 of 3 guitars
- Possibility to connect regular guitars
- Pre-synth sound effect loop (or output to amp/voice pedal)
- Import modelled guitar sound (Antares?) from synth C to the other two synths A & B

- One-or-many selection of up to 3 synth units.
- Full customization of VOL and S1/S2 transport to each synth unit.
- Full GK switching (no US-20 bug circuit)
- Possibility for external 12V powering.
- Noiseless swithing.


GKMX-33 Inputs and Outputs:
================================================
- 3 GK inputs and 3 input guitar jacks.
(Note: The jacks allows you to connect a regular guitar to GR-55)

- 3 GK outputs for driving 3 different synths.

- INSERT jack
GKA and GKB GTR signal is either the raw GTR signal or the optional signal inserted into the INSERT jack.
(This allows a AutoTune for guitar pedal  to be connected as GKC to process the raw input signal and then the modelled output
may be brought back as GTR input for GKA and GKB synth units).

- SEND jack
Buffered output to connect the guitar GTR signal (or INSERT signal) to an effect loop, directly to amp or into a Voice pedal for tune detection.

- RECIEVE jack
If connected this is the signal that will go to the GK A,B synths. This allows a pre-synth effect loop on A and B.
(Note: GKC always gets the raw guitar GTR signal).


SEL Footswitch:
================================================
SEL - Allows you to select (cycle trough) one of the guitars connected to 1,2,3

S1/S2 Footswitch:
================================================
S1/S2 - Sends S1 and S2 commands to the S1/S2 enabled synths by foot.
(convenient if you're playing a guitar without S1/S2 switches).

A, B or C states
================================================
Terminology:
Each output unit (A,B,C) has three state parameters:
VOLSTATE
   ON:  The VOL settings of the GK pot is transported to unit.
   OFF: 5.0 Volts is transported (i.e. full volume/full expression)
S12STATE
   ON:  The S1 and S2 signals are is transported to unit.
   OFF: The S1 and S2 signals are kept in "high" state to unit.

ONOFFSTATE:
This parameter enables/disables the sound of a unit by enabling transport of signals.
   ON:  STR1-STR6 + PIN9 is transported to unit
        VOL depends on unit VOLSTATE
        S1/S2 depends on unit S12STATE
   OFF: STR1-STR6 + PIN9 is silent
        VOL=0V
        S1/S2= high state

LED Indicator "ON"
   BLACK   if ONOFFSTATE=OFF (no sound)
   RED:   if ONOFFSTATE=ON
LED Indicator "S1/S2,VOL"
   BLACK   VOLSTATE=OFF and S12STATE=OFF (Only sound transported at full VOL)
   GREEN   VOLSTATE=ON  and S12STATE=OFF (Sound and VOL/EXPR setting transported)
   YELLOW    VOLSTATE=ON  and S12STATE=ON  (Sound, VOL/EXPR setting and S1/S2 transported)

HOW TO OPERATE THE A, B, C FOOT SWITCHES
================================================
Single-stomp:
Each single-stomp will enable or disable the unit ONOFFSTATE ON/OFF (enabling/disabling individual synth sound)

Double-stomp:
- If the output is not already enabled, this will enable ONLY the selected unit and DISABLE the other two units.
- If the output is already enable, this will toggle the unit VOLSTATE ON/OFF without gap in sound.

Long duration (>2 sec.) hold down:
- If the output is not enabled nothing happens.
- If the output is enabled this will toggle the unit S1S2STATE ON/OFF without gap in sound.

/CodeSmart
But I got more gear than I need...and I like it!

gumbo

..just when your wife thought she'd got you back again...... ::)
;D

Read slower!!!   ....I'm typing as fast as I can...

CodeSmart

Yup dear Gumbo, she thought she had tied me up, but she was all wrong ;D
I told her the color of the year is YELLOW and that I need to follow the fashion. She understood perfectly when I put it like that 8)

Just ordered a programmer for PIC Microcontrollers and a couple of different chips to smoke during the education process.
This will be fun. No experience of PIC's but how difficult can it be?
It will save some valuable board space to decode the action of the footswitches using a tiny little computer (or two).

I know I got a bit carried away this time trying to have three outputs with true switching so this project may take a loooong time ::) 

But I got more gear than I need...and I like it!

gumtown

Here is a project i started a while ago, but on hold for a while too,
using PICKIT-3 you can program the fancier chips with it and do in-circuit debugging.
https://www.vguitarforums.com/smf/index.php?topic=7852.0

Check out the poor quality video in it to see it work.
I is basically a 4 in 4 out patch/midi based GK switcher, capable of routing each string seperately
with inputs for 4 programmable CTL pedals and an EXP pedal.
Also uses a A/D channel to send midi cc# for signal amplitude values (something the GR-55 was misssing).
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

CodeSmart

Thank you Gumtown. I've seen it and I envy your skills. It's very complex.
I'm unfortunately at cave level with MIDI and it also introduces a display and keys etc. adding up to a lot of code. But I sure recognize the advantage of having the switcher controlled from the outside. We'll see. I've to walk the walk first.
But I got more gear than I need...and I like it!

datsunrobbie

I know it is probably of little interest to most, but would it be possible to incorporate a couple of connectors for the first-generation Roland guitar synths into such a switcher? The original connectors have been out of production for years, so I'd guess using DB25 parallel printer connectors (or something similar) would be the way to go, with a custom-made cable to go from the box to the Roland devices. For me, the Ultimate ultimate switcher would allow connecting my VG-99, GR-55, VGA-7, and GR-700 to my G-707 and a couple of GK-2/3 equipped guitars and allow switching between them.

The work you guys are doing on this is quite frankly amazing - codesmart, if you're at "cave level", i'm still wandering around outdoors  :D

CodeSmart

Naa, the unit I'm going for is a 3 guitar to 3 synth switcher using the regular 13-pin connectors. IF other connectors are to be used, there need to be some converter cables outside the box.

I've been traveling for a while (I'm happy to have met our great moderator Elantric in CA :) )and got a lot of regular work to do so I plan to move forward with this project sometime after or during the summer. Most things are figured out and I now feel comfortable with programming the PIC microcontrollers that will reduce the number of components.

Soon also need to order a couple of houndred momentary SPST foot switches and a new batch of 1-m cables from Asia, since I virtually sold out of cables.

Regarding MIDI, does anyone have ideas of what you want you control if I put a MiDI connector on the box?

But I got more gear than I need...and I like it!

Elantric

I would desire GK-VOL, S1, S2 and a Spare user control (running on GK13 pin #9 ) all have capability of being mapped to user defined MIDI CC# controllers.

Then the "MIDI Out" from a future  "GKMX-xx" 13 pin switch box may be connected to a GR-55 or VG-99's MIDI Input and drive one of the Eight Control Assignments offered in GR-55, VG-99.

CodeSmart

Hm, then I guess we need a display and extra buttons to set things up, or an interface to set things up using an external device/computer. Unfortunately up goes the price.

I had an idea for MIDI In, corresponding to that of my Marshall amp, which is a "learn" button. You select the synths you want to sound and routing of VOL ,S1S2, press the "learn" button and then store them at the next PC command. When receiving the same PC number at some other time, the switcher puts itself in the stored configuration. This feature would not require a display. The learn mode could be invoked by pressing two footswitches simultaneously.
But I got more gear than I need...and I like it!

CodeSmart

Guys, for the guitar switching part:

Is there a common Roland GR-55, VG-99 MIDI command to change the System GK-SET in the synth(s)?

Naturally it would be very nice if they changed GK-SET when selecting a new guitar... :D

But I got more gear than I need...and I like it!

CodeSmart

Building the old GKMX types right now to have something ongoing, but I have received 500 pcs new GK connectors and 50 gold plated 13-pin cables. On its way in are also 300 pcs premium footswitches and 300 pcs super quality guitar jacks. A significant investment in hardware for a hobby project. So rest assure I'm dead serious continuing this path  8)

I hope to produce some type of GKMX-33 at the end of the year or beginning of next. It will have 3 GK(+guitar jacks) inputs and 3 fully switched GK outputs. Smooth and silent switching. Assignable S1/S2 and VOL. The unit will probably also have an integrated subsonic filter for piezo pickups. (I think also GK pickups may benefit from this feature as I get rumbling noise from my tremolo sometimes).

Possible MIDI features not desided yet.

Footprint/enclosure same as GKMX-41/42.
Color: "GP-10 yellow".

I wish I had more spare time... :P This is fun!!!
But I got more gear than I need...and I like it!

CodeSmart

Wow, was it June when wrote here the last time! Time really goes fast. Anyhow, during this time I made the GKPX-14 and the GKFX-11 ( http://www.primovasound.com ) to sort of escalate up the knowledge tree. More up to date with SMD (Surface Mount Dirt, "one sneeze and all is gone"), Subsonic Filters, Microcontroller noise issues on 13-pin circuitry and limited coding resources, I think it's time to think about this project again. During this time also the GP-10 arrived with its lack of "normal" MIDI.
So, I might drop the MIDI ideas I had.

Instead I'm thinking about a GK output "normalization" procedure. Let say you have your favorite GK guitar at input 1. In the middle of the song a string break (or the GK cable start to fail). In panic you grab number 2, hit the foot switch and (gently smiling) continue to play. In this scenario it would be very nice if the two guitars had the same output level on a string by string basis. How could that be realized?

Well, if the switcher allows you to configure the gain level of each string of each instrument individually this would be possible. First connect instrument 1 to your synth and setup a perfect tracking. Then switch to guitar 2 and adjust the gain in the GKMX pedal until the level meters show the same reading as for instrument 1 and I think you're pretty much home. I'm well aware this does not cover the other settings like distance etc. But it might cover the major difference between guitars. What do you think?

Also these gain settings allow you to tweak instruments that are a little bit to hot or a little bit to weak on the signal.

For the output synth unit control (remember this is planned to be the first real hex switcher I know of) it also requires full gain control of all the strings to do a perfect mute.

So right now I'm going order some stuff and build myself a testing playground in a pace I can politically handle toward the war department. This is just a hobby and it might take some time.

I'll be back whenever I have further info.

If you think my ideas are good or bad, please let me know :)
/Robert
But I got more gear than I need...and I like it!

gumbo

Quote from: CodeSmart on October 24, 2014, 03:23:50 PM
Wow, was it June when wrote here the last time! Time really goes fast. Anyhow, during this time I made the GKPX-14 and the GKFX-11 ( http://www.primovasound.com ) to sort of escalate up the knowledge tree. More up to date with SMD (Surface Mount Dirt, "one sneeze and all is gone"), Subsonic Filters, Microcontroller noise issues on 13-pin circuitry and limited coding resources, I think it's time to think about this project again. During this time also the GP-10 arrived with its lack of "normal" MIDI.
So, I might drop the MIDI ideas I had.

Instead I'm thinking about a GK output "normalization" procedure. Let say you have your favorite GK guitar at input 1. In the middle of the song a string break (or the GK cable start to fail). In panic you grab number 2, hit the foot switch and (gently smiling) continue to play. In this scenario it would be very nice if the two guitars had the same output level on a string by string basis. How could that be realized?

Well, if the switcher allows you to configure the gain level of each string of each instrument individually this would be possible. First connect instrument 1 to your synth and setup a perfect tracking. Then switch to guitar 2 and adjust the gain in the GKMX pedal until the level meters show the same reading as for instrument 1 and I think you're pretty much home. I'm well aware this does not cover the other settings like distance etc. But it might cover the major difference between guitars. What do you think?

Also these gain settings allow you to tweak instruments that are a little bit to hot or a little bit to weak on the signal.

For the output synth unit control (remember this is planned to be the first real hex switcher I know of) it also requires full gain control of all the strings to do a perfect mute.

So right now I'm going order some stuff and build myself a testing playground in a pace I can politically handle toward the war department. This is just a hobby and it might take some time.

I'll be back whenever I have further info.

If you think my ideas are good or bad, please let me know :)
/Robert

Love the ideas  (it may be because of my own warped sense of what is bound to be important one day, though..)
Please stay in touch in between War Council Meetings..   :D
Read slower!!!   ....I'm typing as fast as I can...

whippinpost91850


gibvictory

I simply want to be able to use two Roland Ready guitars into my GR 55 without switching the cable. A simple two 13 pin in to one 13 pin out into the GR would be all I need. I assume a A/B switch would be necessary. I only using the GR55 for some synth patches and the occasional modeling. The synth is only being used on a dozon or so songs live. I'm nowhere near as sophisticated a user as most of you. I have a separate guitar rig.

CodeSmart, the GKMX-3 is unavailable on the link to your products.

Is there anything else available for my needs? Is there a link to a DIY project for what I'm seeking?

CodeSmart

Quote from: gibvictory on December 28, 2014, 12:09:09 PM
I simply want to be able to use two Roland Ready guitars into my GR 55 without switching the cable. A simple two 13 pin in to one 13 pin out into the GR would be all I need. I assume a A/B switch would be necessary. I only using the GR55 for some synth patches and the occasional modeling. The synth is only being used on a dozon or so songs live. I'm nowhere near as sophisticated a user as most of you. I have a separate guitar rig.

CodeSmart, the GKMX-3 is unavailable on the link to your products.

Is there anything else available for my needs? Is there a link to a DIY project for what I'm seeking?

Hi, to my knowledge there's no DYI for this. It looks I might have a GKMX-41 for you (4 in 1 out switcher) in 1-2 weeks. Or you might ask Wayne, member drjoness2001 if he can make one of his GK-20 (2 in 1 out) for you. My work with GKMX-33 is ongoing but there's no such product available yet.
But I got more gear than I need...and I like it!

gibvictory

Thanks for the reply. I'm going to PM drjones2001 to see if he has a GK-20. That would be ideal and i assume cost effective for my needs. I will look more closely at your GKMX-41. I may be able to grow into it in the future.

CodeSmart

Have had some days off now and this is what seems possible to do:



Q: Can I select one of 3 guitars? - Yes
Q: Does all GK input also have a 1/4" jack - Yes
Q: Can I program gain for each hex string on all inputs to normalize guitar string levels? - Yes
Q: Can I flip/invert hex order so filter gets the correct string even if GK upside down - Yes
Q: Can I program gain for std pups to normalize when switching btw Fender and EMG guitars - Yes
Q: Can I program gain/attenuation of the 1/4" jack for each input - Yes
Q: Can I adjust blend of GK pin 7 and the input of 1/4" jack ( mix piezo composite/std pups) - Yes
Q: Can I choose to have a Subsonic Filter individually ON per input? - Yes
Q: Can I variable adjust the filter frequency per string/input, let's say one input is a MIDI violin? - Yes

Q: Can I have a pre synth FX loop? - Yes
Q: Can I connect a future ATG as synth A and insert the modeled output on pin7 to synth B and C? - Yes
Q: Can I control the INSERT on/off with some of the controls? - Yes
Q: Is the SEND output buffered? - Yes
Q: Is the RECEIVE input buffered? - Yes

Q: Is this a TRUE switcher so I can assign other things than Volume to the guitar knob - Yes
Q: Can I direct S1/S2 guitar buttons only to selected device(s) - Yes
Q: Are all switching free from 'pops' and 'clicks'? -Yes

Q: How many analog expression pedals can I connect? - Max 3, one for each synth unit.
Q: Can the expression be unrelated to guitar volume knob? - Yes
Q: Can the expression pedals instead be assigned to any CC# MIDI command? - Yes
Q: If I use a standard guitar can Ctrl1/Ctrl2 foot switches be used for S1/S2? - Yes
Q: Can the Ctrl1/Ctrl2 foot switches be used to send out CC# MIDI? - Yes
Q: Can I connect Ctrl3/Ctrl4 to GP-10/GR-55 and use Ctrl1/2 as simple external switches? - Yes
Q: Can I use the Ctrl3/Ctrl4 jack to external switches for CC# MIDI control? - Yes

Q: Can I program to have ground lift on unit B and/or C (relays)? - Yes

Q: Can I download and flash new firmware using a PC via the USB connector? - Yes
Q: Can the unit have "patches", i.e. different setups? - Yes
Q: Can I switch patch using MIDI Program Change commands? - Yes

Finally:
Q: When will this unit be available? - Don't know. There will be two packed boards, one digital and one analog, packed with SMD stuff. There will be several board iterations and lots of difficult coding. I'm afraid of the MIDI and USB stuff.
Q: Will it be expensive? - Yup
Q: Do you expect to sell many? - Nop
Q: Why do you do this? - To see if I can make the most complex GK switcher on the planet.  8)
But I got more gear than I need...and I like it!

Elantric

I might have to order one of these  - or carve out time in my schedule  to assist in your R&D ;)

whippinpost91850

That is totally awesome. Probably overkill for me, but would maybe just buy one because you did it.. 8)

gumbo

Hi Robert...beautiful!!!
...I guess those loooong Northern winters give you plenty of time to contemplate!!   :D

...to take my mind off adjacent (!) bushfires and between 38C & 44C I tried contemplating also extra (switching) remote jacks that would enable remote foot switches to be used for CTRL1 & CTRL2... when plugged in would bypass the inbuilt foot switches..    ;)

..stay warm!
Peter
Read slower!!!   ....I'm typing as fast as I can...

CodeSmart

Quote from: gumbo on January 06, 2015, 04:42:29 AM
Hi Robert...beautiful!!!
...I guess those loooong Northern winters give you plenty of time to contemplate!!   :D
Peter
Thanks, I saw on TV you are in trouble. Yes it's cool here. Time to think.

Did the detailed math today and realized I need a severe amount of I/O. The 44 pin PIC18F4550 Microcontroller needs to handle USB, MIDI in/out, 6 foot switches, 3 single colored LED, 3 double colored LED, 3x6 channel switching ship, 4 pcs hex volume chips, handful regular CMOS switches, 2 relays, LCD display, 4 AD converters, S1/S2 I/O, a handful digital potentiometers and 3 DAC converters + more stuff.

It all boiled down extending the Microcontroller with a few additional Microchip I/O and DAC extension chips. A lot of data sheet reading going on right now. :P

The software will be a nightmare with both I2C and SPI similar protocols running as well as MIDI protocol and USB things.

Plan is to make a development PCB with the core digital stuff to develop the required foundation software/drivers for the next generation PCB. I'm starting from scratch with most things here but I hope to pull it through. The LCD will be very useful to have as soon as it is up and running.

Unfortunately I have to go back to regular work soon...  ::)
But I got more gear than I need...and I like it!

whippinpost91850


Elantric

QuoteDid the detailed math today and realized I need a severe amount of I/O.

http://bit.ly/1wlMNiO






gumtown

If you need some help with this, I am happy to lend a hand.
This project is similar to what I started 2 years ago, but I had problems trying to prototype with SMD chips (and my failing eyesight).

You may have seen this
https://www.vguitarforums.com/smf/index.php?topic=7852.msg55571#msg55571
in video demonstrates the core CPU control and lcd graphics using the custom CGA memory of a typical 2x16 display.
My project took the GK switching one step further and enables separate strings to be routed to one or all GK outputs (probably overkill).
The plan was to use modular serial interfacing to individual PIC cpu's one each I/O module, and have a plug & plug system the user could plug in the required amount of input or output 13 pin GK modules, and the core CPU would do an address inventory of what is plugged in on start up (another overkill).
Another option was to have the normal guitar input sent via A/D conversion to send variable midi cc# on guitar level (something quite useful the GR-55 was missing that the Boss GT's have).
If you read the txt files you will see how I have used the eeprom to store patch data (8 user and 8 preset), and other useful info like last patch selected before power off.

I am handy at doing the programming and some circuit design and testing, just the SMD stuff, and I haven't done PCB design for quite some years.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/