PRIMOVA - GKMX-42 Project – Box with 4 GK/4 Jacks in 2 GK out

Started by CodeSmart, August 03, 2013, 10:47:23 AM

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tekrytor

I've been terribly busy at work and not enough v guitar time, so I just discovered this thread. Great project!

I probably read past the answer, but can the GKMX-42 run both the GK signals out in parallel, to drive two GR/VG simultaneously?

The calculations all look reasonable, but if you compare the prices to an actual GR-55, it's a bit hard to justify. However, there are few options to do this, so it's definitely interesting. I might be able to spring for a kit at some point, if that were an option.

I'm thinking of attaching it to also feed one of Bill Bax's Breakout Boxes, for total freakiness and surround mania, along with a V-Bass and a GR-55, add looper, ad nauseum:D. It's all here... going through a GKP4 now, but it's hard to switch on the fly with those little toggle switches.

+1 for doing this project!
SY-300/BeatBuddy/VoiceLive 3/GR-55(v1.50)/33/1/50/700/VGA-7/V-Bass, Yam-G10, GPK-4, DIY X-Bee HighlyLiquidCPU "Cozy-Lil-Footie", FCB-1010, other MIDI stuff, Godin Freeway SA and various other GK equipped controllers, Sonar X1, Audacity, KXstudio, Misc devices

CodeSmart

Hi guys,
Regular stuff (US-20 style):
* All pins STR1-STR6, GTR and PIN9 is routed in parallel to both unit A & B.
* Guitar S1, S2 is only sent to ONE unit only controlled by A/B foot switch.
* VOL_A and VOL_B is controlled using the A/B and BOTH foot switches. To silent a unit voltage VOL is brought down to 0V.

Geek stuff:
* Enabled unit(s) normally gets a VOL voltage according to guitar VOL, but optionally if an ext. volume pedal is connected
the final enabled unit voltage is based on guitar voltage or an internal 5V reference (5V=Max volume).
This is controlled by a switch. There is one optional volume pedal and switch pair for unit A and one pair for unit B.

* Box foot switch S1/S2 goes directly to either A or B or according to A/B foot switch. Mode is controlled by 3-way rotary switch.

* To support guitars (other than GK-3) requiring more than totally 200mA a 12VDC to +/7V, voltage converter/regulators have been added to the board.
There will be a connector for an optional 12VDC supply on the box. Ext. DC power connector and wiring same as on any normal BOSS/Ibanez stomp box.

Tonight I finalized the new PCB design and hope to send it for production tomorrow.

Here's the new PCB. It's getting pretty crowded. But it's a Beauty  ;D


Best
Robert (CodeSmart)

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

CodeSmart

Gass, I re-read your question. To clarify what I just wrote. Each buffered input is mixed (using an OP-amp) with  the GTR signal of the corresponding GK guitar channel. This means if you have four hands you can play two out of possible eight connected guitars at the same time  ;)  The final GTR (a mixture of the buffered pups and the regular pups on the GK-guitar) is always routed to both unit A and B directly or via the optional Send Receieve jacks. So regular pups are not affected by A/B/BOTH switches, only hex-pickup synth volume.

Tekrytor, regarding the price I'ts not settled. I pretty much need to to build a few boxes and see where I get in terms of PCB production+components, jacks,footswitches etc + box with drilling, painting and printing. We'll see. Of course I can provide only a built and tested PCB without the additional external hardware if you like to do the rest yourself.

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

tekrytor

Very cool CodeSmart! The price is really quite fair when one considers all the thought, time and work you're putting into this and all the things it can connect and manage. I've built some prototypes, kits and my own designs over the years, so I can appreciate the hours it takes to make an enclosure for example. Start adding up the time and it's usually not worth it if you can buy it complete. Time is the enemy, unless you're playing in 4/4 :)
SY-300/BeatBuddy/VoiceLive 3/GR-55(v1.50)/33/1/50/700/VGA-7/V-Bass, Yam-G10, GPK-4, DIY X-Bee HighlyLiquidCPU "Cozy-Lil-Footie", FCB-1010, other MIDI stuff, Godin Freeway SA and various other GK equipped controllers, Sonar X1, Audacity, KXstudio, Misc devices

whippinpost91850


Gassghost

Thanks CodeSmart! I'm just giddy with excitement. I'm already making room on my pedalboard!

Gass
GR-303 updated electronics, Stetsbar, Sustainiac
GR-808 (original) + Stetsbar (FOR SALE)
79 Strat w/ GK-2A
Eastman El Ray 1 and El Ray 3
94 Fender Tele w/GK-2A, Stetsbar
2 Fender GTX 100's
VG-99, GR-55, FC-300
And studio full of stuff

CodeSmart

Hi guys,
Please visit my new homepage at www.primovasound.com

Please vote for GMX-41 or GKMX-42 so I know which one to build most of.
As the page suggest, please vote by sending an e-mail to sound@primova.se and tell me what you think.

Thanks
Robert (CodeSmart)
But I got more gear than I need...and I like it!

dedjazzgadgetz

#32
Hi CodeSmart !

A-ma-zing project/offering, Robert ! I appreciate all the effort/passion put into this beaut', as I'd been working on my own smaller 3ins/2outs ultimate switcher https://www.vguitarforums.com/smf/index.php?topic=5627.0 (prototype pictures coming soon !) before my day gig delayed any further experiments, 4 months ago https://www.vguitarforums.com/smf/index.php?topic=9308.msg67053#msg67053... so I know all the hard work you've put into this.

I've been reading your posts and felt the need to clarify something:

I understand your 2-output selection circuit topology follows Roland's US-20: selection is actuated by up to +5volts, for full vol. being present or not on pin 8 GK-Vol / pin 7 Guitar In 1/4" input being shorted or not to ground. Am I mistaking ?

If this is the case, users who will have assigned any function other than Pick-up Volume or Output Volume to their GK potentiometer will experience "bleedthrough"  ("erratic" selection behaviour https://www.vguitarforums.com/smf/index.php?topic=3494.0 :'(  ) That's the reason I've chosen to switch all 13 GK pins in my GK-boxes...

Hoping the very best for your project,
Dedjazz
No excuses, no limits

CodeSmart

Hi Dedjazz,
I've been seeing your project here on the forum for a while, but I wrongly thought you had given it up. If you have had a unit ready I would not have started this project. Happy to hear you are making progress  :D

Yup, you are right, my integrated A/B selector is in most ways a US-20 compatible clone (not switching hexaphonic signals etc.) mostly because there's space issues adding more IC's within the current footprint.

With my box you can at least separate the VOL signal so one Unit gets guitar knob voltage and the other Unit gets VOL voltage from a EV-5 foot pedal independently. That could perhaps help some of the scenarios :P

To get something deliverable this year (i.e. as fast a possible), increasing the board size was a No-No so I decided to go for the Roland (simple US-20) approach.

To me the INPUT switching possibility with phantom power is the most important feature of the board.

Hoping the best for your project as well
Robert


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

dedjazzgadgetz

#34
Hey, Robert !

I can't kick myself enough for being silent such a long time (sincerely hope I won't have wasted everybody's time on this); in addition to being overwhelmed with work, there were relationship & family issues... very long & sad story indeed.

Yeah, footprint... I thought at first going with CD4052-type of FET gates easy-peazy, but realised the monstrosity of a multilayer ($$$ ! ) board it would have to come down to, to acheive my goal of the smallest Hammond enclosure possible (for my 3ins/2outs, I'm now up to a 1590C, slant-cut, and nowhere as many features as yours sports: whew ! tough act to follow... ) so I went for ultra-miniature military/comm.-grade relays I just chanced upon, that allow switching all 13 GK channels in such a compact box (1590B for the 2ins/1out, 1in/2outs)...

To anyone balking at a greater than $200 price tag for any of Robert's devices or mine, please: Roland is a really BIG corporation (mass production/lower costs... we R&D/build these with our very own hands/passion), Roland's US-20 is flawed IRT device-selection-by-GKvol-setting from the get-go (AND at $215+tx for <$4 of parts ? Come on ! ), they haven't bothered with any input sel. devices (well, I can appreciate the tech. challenges here !), rolling your own is perfectly feasible but long-winded & risky if not extremely careful (I've had some of my homemade stuff crap-out on me, mid-song... great: what do you do, then ? this stuff HAS to be road tested/indestructible !)...

Well, anyways... sorry for spamming/rambling on/hijacking your thread:  I think your project is truly awesome !!! (your Eaglesoft board in itself is a beaut' ! )

Keep it up !
Dedjazz

 
No excuses, no limits

CodeSmart

Yeah dear Dedjazz,
You are completely right. The component cost is really more than you want. I have searched all over Europe and found that I can get best price in Germany. So I'm importing most of the things from there. Swedish currency (SEK) is very strong so I can't buy stuff locally in Sweden. We talk 3-4 times higher price. For switches and other components I have started looking in Asia. Yup, low price but you have to invest in very large lots. Regarding the board it's a two-layer with thread mounted components. It's being produced in China. To get more stuff onto the board I would need to go into 4-layer and surface mount. But then the PCB production cost would double and I can't mount components in a simple way. That's way I try to keep away of the price issue until I get the first batch mounted, drilled, painted and printed. I'm doing my best to get a low price but still it's a mighty challenge.

I also recognize that to get more than a handfull sold the price needs to be as low as possible. But YOU and ME we both know that a device like this is really missing in the market place. As the number of GR-55 users will grow (and it looks they really are) there will always be percentage of guys having more than one GK-ready guitar.

THANK YOU VERY,VERY MUCH DDJ FOR ENCOURAGING ME DOING THIS ADVENTURE  :D
But I got more gear than I need...and I like it!

gumbo

..and I would like to encourage you BOTH to keep going..   ;)

...BTW, let me know when you're about to hit the Big Southern Island, Robert! 

Cheers,
Peter (gumbo)
Read slower!!!   ....I'm typing as fast as I can...

CodeSmart

Hi,
Just ordered 50 pcs GKC-1 Cables to ship with my products  ;D
So I will have 50 GK-cables straight trough Male-Male at the length of 1 meter (3.27 ft) available in a couple of weeks.

I really hope they will be good quality.

You can't just sell the box and expect people to solder these "#¤%%&¤ cables by hand.
I hand-soldered one the other night and it took me ages to get it working properly.

And Gumbo...I will leave for AC/DC-land Sep 15:th :)
But I got more gear than I need...and I like it!

mojo thorne

I think that expecting something like what's being planned here to sell for $200 is a bit crazy, particularly considering what a US-20 and its limited feature set sells for new.  I'd be willing to spend $300-400 to have the features talked about here, or in the other thread pertaining to dedjazzgadgetz's tiny miracle box.

Having the ability to switch between 2 GK guitars, driving 2 synths, a standard Guitar input (to access the GR-55 effects with a non-GK guitar), an FX loop (for the normal pickups on the GR-55), and the ability to control the S1/S2 functions with a footswitch would easily be worth the price, since it would allow me to go from three pedal boards down to 1 1/2.  That would save me enough floor space and back pain to make bringing my GR-55 board to my acoustic gigs.

The fan-out possibilities mentioned in dedjazzgadgetz's thread are also very interesting to me from a recording perspective, but my main concern is with live gigging.

I have a question about the power distribution for 13 pin guitars.  Do non-GK guitars with 13 pin outputs also have a requirement to receive power from the synth?  I have a strat with a GK-3 and a Godin xTSA that I use as my main guitars.  I'm assuming that both guitars would still work equally well with this switcher.  This is probably a stupid question... I'm certainly in the minority here as I am not a tech guy... but I want to be sure as I may add another Godin to my arsenal.

Elantric

#39
All 13 Guitars with 13 pin output I'm aware of always use the Host 13 pin Processor (VG-99.GR-55, etc)  to obtain +7V / -7V @ 200mA power. This is truw for Roland, Yamaha, Axon, Graphtech Ghost, RMC Piezo/ LR Baggs Piezo (old Godins) and is  the reason Roland never offered a 4 input GK 13 switcher.    The RMC Piezo type guitars (Godin) typically consume the most power @ approx 110mA. Remember you want Power supply headroom, (i.e. do NOT draw more supply current than available) or else clipping / distortion occurs.   

I think any GK Switcher design should consider only providing +7V/-7V power only to the currently selected 13 pin Input. Who is playing two 13 pin guitars at same time? (besides Warr / Stick Players with two GK-3's installed)

mojo thorne

Thanks for answering.  That makes sense.

Looking at the design for this box, doesn't it allow switching for the GK guitars?  I thought that was what the toggle switch was for.  Didn't occur to me that it would be powering all of the GK guitars simultaneously.

CodeSmart

Yes it powers all 4. No problem with GK-3.
I Have messured the amps.
You can connect 12VDC adapter to it to get
abt. 100mA to each guitar (to be verified
when I get the boards).

Talked directly to RMC.
He said 25mA for RMC geared guitar.

Elantric, where do you get
100 mA from, have you measured?

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

CodeSmart

What I try to say is:
-GK-3 guitars don't need the ext. adapter.
- For other guitars, connect a 12VDC adapter,
0.8A - 1.2A and you are safe.

To be safe, In the manual I recommend an adapter if
more than two 13-pin guitars (regardless of type).
But I got more gear than I need...and I like it!

Elantric

#43
QuoteElantric, where do you get
100 mA from, have you measured?

Just an estimate -based upon the PolyDrive II
http://www.rmcpickup.com/polydriveii.html



CodeSmart

Hi Elantric, I feel silly but I can't find the numbers required to calc the milliamps  8) Do you know how long a 9V battery lasts in this unit? Even with time and battery mAh known, what is the penalty of doing the 9V to +/- 7V conversion?
But I got more gear than I need...and I like it!

Francis 7

#45
Well count me in as interested, though I'm also interested in dedjazz'. What a great problem to finally have! Plus I'll finally be rid of my GKP-4... anyway, just offering my encouragement and interest. PM me when ready!

CodeSmart

Hi,
Just got most of the components delivered on Friday, however a few intems incl. PCB is still missing.
So far I have received 6-7 requests for units, so that only leaves about 3-4 units remaining of the first batch.

If you want to show your interest in any of the products shown below, please send a email to sound@primova.se
My web page is www.primovasound.com



AS OF TODAY IT LOOKS THIS WILL BE THE PRODUCT LINE

GKMX-42 abt. 210-270 Euro (tbd).
The delivery includes:
- GKMX-42 unit (4GK+4Std guitars in - 2GK A/B out (US-20 compatible), S1,S2, Send-Rec jacks, VOL A+VOL B jacks)
- 2 sets of 1 meter 13-pin cable with latched straight male connectors.

GKMX-41 abt. 170-220 Euro (tbd).
The delivery includes:
- GKMX-41 unit (4GK+4Std guitars in - 1GK out, Send-Rec jacks )
- 1 set of 1 meter 13-pin cable with latched straight male connectors.

GKSW-42-KIT abt. 120 Euro (tbd.)  - Premounted and tested DIY circuit board (same as mounted in GKMX-42).
Flat cables and all cable connectors included. Documentation and wiring details will be available for download.
No other hardware included (box,switches etc.)

GKMX-C1  2 pcs 1m GK-Cable (Roland GKC-1 clone) abt 40 Euro (tbd)
Set of 2 cables 1 meter length 13 pin cables with latched straight male connectors.

The prices above are excluding shipping cost and excluding Swedish VAT 25%.
Private customers in EU normally pay VAT.
Customers outside EU do NOT pay VAT.
(100 Euro = 132 USD = 85 GBP = 148 AUD = 874 SEK)

I hope above looks ok to you guys.
The GKMX-42 comprises about 170 individual components that needs to get assembled...  :P

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

CodeSmart

Hi Folks,
I got the 25 PCB V2 delivered, second design  ;D
I put components one the first one and it really was a success. Everything worked gracefully.
Compared to the US-20 this unit does not care if the A or B is connected, it gets power by any device.
If you connect many current hungry guitars with (non-GK-3) pickups (as Elantric discussed earlier) requiring lots of milliamps,
you plug in a cheap DC adapter between 9V-13.5V DC (preferably 12VDC),
to take the strain of your synth unit power supply.



So, now it's just to get the other PCB mounted, paint the already drilled boxes and get rolling.
Unfortunately !!?!! I'm leaving for Australia for 5 weeks in next weekend so shipments need to wait until I get back.

Today I also got a e-mail from my manufacturer of cables to get bundled with the units (1 meter (3.28ft) 13-pin cables) is shipped.
Isn't life great sometimes  :D

Please send  an e-mail to sound@primova.se if your are interested in getting a 4 GK and/or 4 standard jacked guitar stage switch box with effect loop jacks and with (GKMX-42) or without (GKMX-41) an enhanced US-20 device in a footprint of 170x120mm (7x4.7 inch). The GKMX-42 unit also has configurable S1/S2 foot switches and jacks for EV-5 volume pedals.
With the effect loop Send jack available in both products, you can steal the standard pup signal to your Marshall stack before it gets dirtified by the GR-55 digital noise, with highs kept due to high impedance inputs.

Friday the 13'th September I'll be using this unit myself to switch between a GK Ibanez, a GK Fender Strat and a non-GK Gibson Les Paul Traditional in front of abt. 200 motorcycle guys. I built this unit for my own needs. I'm sure you have use for it to  ;D

For geeks at this forum( Hi Elantric), here's the internal voltage measurements:
Synth A device powering the unit: +6.82, -6.70V
Synth B device powering the unit: +6.83, -6.70V
9V adapter powering: -7.18, 7.26V
12V adapter powering: -7.19, 7.27V
13,5V adapter powering: -7.2V, 7.27V
15V adapter powering: -7.2V, 7.28V
Tried also 17.5V but then smoke started to come out of the protection diode, rated 15V.  8)
But I got more gear than I need...and I like it!

mojo thorne

Can the standard guitar inputs and effects loop be used together?  Just wondering if the effectsin the loop could be used with the normal pickups from a GK guitar and a non GK guitar without reconfiguring anything during a gig.