Eurorack Synth Build for Roland GK-3 & Cycfi Nu Guitar Single-string Processing

[GuitarBuilder]

Module post series: 13-Pin Input Breakout, Part II

We featured the 13-Pin Input Breakout module last week as a great option to interface a Roland GK compatible guitar with the Eurorack Modular environment.
In part II, let's focus on the options for this module, namely, the maximum gain of the seven low-noise amplifiers. When ordering this module, one can select one of three gain options: 20dB, 30dB, or 40dB. These correspond to amplification factors of 10x, 30x, and 100x (adjustable from zero to maximum. So which one do you chose?

That depends on how you intend to use the module:

A) Feeding the GK string and guitar audio into a module that expects guitar-level signals, such as the SynQuaNon ATG module or a pedal I/O, for example. In this use case, little amplification or even attenuation is advisable and the 20dB gain option will be fine.

B) Feeding the GK string and guitar audio into a module that expects +/-5V signals, typical of most Eurorack modules. This requires approximately 30x or 30dB amplification.

C) Feeding the GK string and guitar audio into a module that expects +/-10V signals. This can be accomplished with the 100x or 40dB amplification option. One interesting side benefit is that this amplifier can be driven into mild clipping and add distortion to the signal if desired.

Keep in mind that there is a trade-off between maximum amplification and noise - the higher gain amplifiers, despite using low-noise opamps, will exhibit higher noise levels, albeit only noticeable at high volume levels.

Lastly, all three amplifiers can be configured to be attenuators, with gains of zero to one. This is done by placing the 7 jumpers on the back on the left side of the gain selection header. More on this next week when we discuss the 13-Pin Output Breakout module!

[AlakaLazlo]

Module post series: 13-Pin Input Breakout

Today we feature the SynQuaNon Eurorack 13-Pin Input Breakout module. This module opens up a whole new world for guitarists who either already own a guitar with a Roland GK 13-pin pickup or are planning to get one!

Welcome to the world of guitar synth nirvana!

Congratulations on bringing your system to market!

[GuitarBuilder]

Congratulations on bringing your system to market!

Thanks very much!

[GuitarBuilder]

In my first post of this thread I showed a ModularGrid representation of a hex ATG processor.  Nine months later, after much design and experimentation, it is done!


SynQuaNon Hex Autotune for Guitar Processor with GK Input and Output

This small Eurorack case starts with the 13-Pin Input Breakout (for GK guitars - one could also substitute the Nexus Input Breakout for Cycfi Research Nu Multi guitars).  The 6 string and 1 passive pickup audio signals are available via a header on the back of the module, in addition to the jacks on the front panel.

Each ATG module is designed to function exactly as if it were installed in a guitar and can accept all 7 audio signals via the standard hex pickup input on the DSP board in the back of the module (the passive signals are used in bypass mode and are not processed with AutoTune).  A single ATG module presents a mono, mixed output after hex processing the string audio.  However, if one routes each hex string signal to a separate ATG module, the 6 outputs represent a hex AutoTuned signal that can now be passed on to BOSS/Roland guitar synths for further processing.  This is done via the 13-Pin Output Breakout module on the right.

Why am I doing this?  Because I really love what the ATG does for guitar, but was frustrated with the fact that one cannot simultaneously use the ATG mixed mono output with GK synths driven by the same guitar, mainly because they can very easily be out of tune with each other.  Now one can put them in series!

.....or just use a Eurorack ATG module all by itself!  It's a LOT smaller than the ATG-1 and does not require routing your favorite guitar!

[chrish]

Cool. I do see a 2 or 3 hp space left in that case. In eurorack that usually means you need another case. 

[GuitarBuilder]

Cool. I do see a 2 or 3 hp space left in that case. In eurorack that usually means you need another case. 

[mooncaine]

In my first post of this thread I showed a ModularGrid representation of a hex ATG processor.  Nine months later, after much design and experimentation, it is done!


SynQuaNon Hex Autotune for Guitar Processor with GK Input and Output

Now that's how life oughtta be.

[admin]

[Wyrtti]

I am late to the show, as I saw this thread only yesterday. This is fantastic! So, I finally got off my derriere and ordered a Convertor+. If it works as well as y'all are saying, I can easily see this kind of 4-6 note poly modular controller system in my future.

This is exciting stuff, thank you!

Topi

[chrish]

I run my converter+ into the send return of the boss sy1000. It tracks great if I take the send off the sy1000 right after the normal mag pup input and into the converter+.

Makes the converter+ osc sound big running it through the SY fxs

When comparing the C+ saw osc to the saw wave on the SY1000, hard to tell only one is analog.

If money were no object, I'd have one of the above 13 pin breakout boxes and 6 of the Sonicsmith Squaver P1 units.

[arkieboy]

When comparing the C+ saw osc to the saw wave on the SY1000, hard to tell only one is analog

The dynamic synth saw wave - and the supersaw - are really good sounding saw waves.  Fooled an ARP owner into thinking I had an Odyssey of some kind 

[jim-analog]

 Greetings,

How did you construct the dynamic/super saw waves? Hardware or software? That's a source that I'm very interested in having access to. I've been contemplating various hardware solutions, but nothing has been built yet. Thanks for reading!

Regards, Jim

The dynamic synth saw wave - and the supersaw - are really good sounding saw waves.  Fooled an ARP owner into thinking I had an Odyssey of some kind 

[jim-analog]

 Greetings,

That's an interesting hook up. By "C+", are you are referring to the S/S Converter or a software program?

  Do you know if it's possible with the GP10? That's the unit I have and I'd like to try a similar set up with the S/S Squavier.

Forgot to add.............YES! That would be a fantastic set up with 6 "converters" to have full hex CV analog! The big goal is to make it more affordable and more accurate.

  Thanks!

Regards, Jim

I run my converter+ into the send return of the boss sy1000. It tracks great if I take the send off the sy1000 right after the normal mag pup input and into the converter+.

Makes the converter+ osc sound big running it through the SY fxs

When comparing the C+ saw osc to the saw wave on the SY1000, hard to tell only one is analog.

If money were no object, I'd have one of the above 13 pin breakout boxes and 6 of the Sonicsmith Squaver P1 units.

[chrish]

Greetings,

That's an interesting hook up. By "C+", are you are referring to the S/S Converter or a software program?

  Do you know if it's possible with the GP10? That's the unit I have and I'd like to try a similar set up with the S/S Squavier.

Forgot to add.............YES! That would be a fantastic set up with 6 "converters" to have full hex CV analog! The big goal is to make it more affordable and more accurate.

  Thanks!

Regards, Jim

yes C+ is the sonicsmith converter+ unit.

Don't know anything about the GP10.

Fortunately Boss Roland came out with the SY1000 and it has increadable sounding simulated analog waveforms, especially in the osc synth section with excellent tracking.

So I don't feel the need to shell out the Buco bucks required to purchase 5 more converter+ units right now.

In side by side comparisons,  there does seems to be a slight perceptible latency advantage with the C+ ,however that could be just brain perception trickery without doing the science.

It even seems the the dynamic synth waves are an improvement over the SY300.

Plus I don't get the SY300 "ice pick in the ear" effect with the SY1000.   

Placing the SY1000 send right after the osc would allow that osc wave to be feed into modular gear and fed back into the SY return. I've done that also however with mixed results. For example,  feeding poly wave audio into one analog filter seems to overwhelm one filter.

It would work if there were 6 audio steams coming out of the SY1000 and into two or three modular analog filters, but I can't find the 13 pin out jack

[billbax]

Hi Guys,

Been watching this topic for a while, and don't mean to mess on GuitarBuilder's great hardware work. Also enjoyed Admin pointing out the Sonicsmith separate string synth demo. 

My question is, could all of this be achieved with a simple GK Mini Breakout Cable costing £80.00GBP, and six daw separate string inputs > audio to MIDI > MIDI > VST instruments etc. I must be missing something?

Bill

GK Mini Breakout Cable

[chrish]

Bill, When I was looking at breakout boxes, I thought that your 13 pin to 7 × 1/4"  breakout cable would be a perfect set up to input the hex pup into 6 sonicsmith converter+ boxes.


I would have plugged the 13 pin plug into one of the two outputs 13 pin jacks on the Roland US20 splitter boxes with the other output going to the VG99.

But then the SY1000 came out of nowhere and it sounded analog with excellent poly pitch tracking.

But for straight interfacing with modular gear, the extra gain stagging on GuitarBuilder's modules with hex metering would be great to own.

Did you notice the 13 pin breakout box in the sonicsmith
Vid?

[scratch17]

The Sonicsmith Convertor+ and Squaver+ have the same analog Audio Controlled Oscillator (ACO) chip. So the conversion from analog audio to control voltage is the same.

The chip designer says he is working on a new faster, more accurate version using digital design that will also support audio to MIDI conversion.

Remember that if you put a Convertor + or Squaver + on each string's hex output, you will need six separate synths, each with its own voice and CV inputs.

I know of no 6 voice modular synth that has separate CV inputs. Of course if you have the money, you could build a modular with six separate mono synths.

Also, keeping six analog modular synths in tune over time can be problematic. Check out the TA Programming Studio MIDI and CV interface. It should work well for a hex guitar setup with CV and MIDI synths. And it will do much more than sync up synths.

Find info at TAProgramming.com.

If the new digital ACO chip is a success, because it will be able to output MIDI, you could use a six voice synth or sampler that supports MIDI Mono mode.

[GuitarBuilder]

Hi Guys,

Been watching this topic for a while, and don't mean to mess on GuitarBuilder's great hardware work. Also enjoyed Admin pointing out the Sonicsmith separate string synth demo. 

My question is, could all of this be achieved with a simple GK Mini Breakout Cable costing £80.00GBP, and six daw separate string inputs > audio to MIDI > MIDI > VST instruments etc. I must be missing something?

Bill

GK Mini Breakout Cable

That is an alternate approach, Bill!  As a matter of fact, I've had that hookup for a while in my studio; one could also use the GP-10 USB audio output for the same purpose.

However, I wanted to follow an analog hardware path as much as possible.  I guess the word "synth" in the post title is restrictive: the idea is to open up the whole world of Eurorack (mostly analog, some digital) effects module world for guitar, where one could create virtually any signal path using commercially available hardware building blocks (perhaps I'm missing my LEGOs!).  Yes, this is a synth forum and folks tend to gravitate to the guitar-to-oscillator part, but I've found so far that one can do quite a lot without any VCOs.

The key missing ingredient is a solid tracking Eurorack direct pitch-CV module; I got very excited about the ACO and look forward to the DACO becoming a commercial reality.  That will break Eurorack the guitar synth barrier wide open!

As a side note, I did get the FTP to work in the Eurorack environment, both in mono (hardware) and poly modes.  While not GK and using a double conversion (guitar-MIDI, MIDI-CV), it would be quite acceptable for non-shredder guitarists.

[billbax]

Thanks Guitarbuilder & chrish for explaining a different approach with access to separate strings. 

Enquiry closed

Bill

[GuitarBuilder]

Here's an older, but still very relevant video on using Eurorack Modular Synthesizers as Guitar Effects Processors:

[GuitarBuilder]

Our first batch of demo videos is now available on the SynQuaNon YouTube channel.  Check them out - like and subscribe to be notified of new ones!

https://www.youtube.com/channel/UCcHTrqMTD-3iOcj4IB0_ItA/videos

[GuitarBuilder]

New demo system and customer videos are up on the SynQuaNon Blog:

https://www.synquanon.com/blog