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Building a processor, incorporating it with banana gear?
MUFF WIGGLER Forum Index -> Buchla, EMS & Serge  
Author Building a processor, incorporating it with banana gear?
Rex Coil 7
Sorry about the vague title. Allow me to clarify, I'll use simple examples to start with.

I'm designing/building a multi-circuit stomp box (let's just call it that for now) using stomp box circuits for use with the type of synth gear that is specified in this very subforum. It's typical "guitar type stomp box circuits" that use hot/ground (aka "tip sleeve") connectors and 9vdc power with the chassis being negative relative to the input power ("chassis negative").

The synth is a banana jack type synth.

QUESTIONS:


Ok, so how do I go about making the two systems work together? I'm aware the signal level of the synth's output will need to be attenuated so as to not overdrive the input stage of the stomp box circuits.

Do I simply connect the stomp box chassis to the synth chassis via a dedicated grounding cable since the banana jacks do not provide a "sleeve" (aka "shield") wire to connect the two cabinets' chassis together?

What of the signal? Do I simply use a banana cable from the output of the synth to another banana jack on the stomp box (relying on the additional chassis grounding wire that would connect the stomp box chassis with the synth chassis)?

I actually have done a search in this subforum for these answers, and while there is most likely information of this sort within these threads I was unable to locate satisfactory answers.

Lastly, understand that this device I am building is for another member (not myself) so getting this ~right~ is of the utmost importance. This person is placing trust in me to provide a properly working setup.

Thank you for your assistance. nodnod
chrisdermo
My understanding is not the most technical but I've done some things like this myself.
Install a 0v banana jack on your stompbox build - use the part of the pcb that would normally be connected to the sleeve of the output 1/4" jack. Connecting this to the banana synth 0v jack will make the two circuits share the same 0v reference I believe.

Attenuation from the banana synth to the stompbox will probably suffice, however you may need to match impedance (with a transformer) if it's one of those funky fuzz circuits that is built to react to a guitar's tone and volume controls. If the idea is to send the audio out of the modular, into the processor, then back into the modular they also likely need an input preamp on the way back into the modular.

Audio signal can go via banana cable if that's what the synth offers as an output, just install banana jacks on the effect box i/o. But, different nana systems use different audio path connectors at different stages of the signal flow, banana, 1/4", 3.5mm, tinijacks etc. If you had the space on your enclosure you could include a couple of input/output jack formats if necessary.

Hope that's been some help!
Rex Coil 7
chrisdermo wrote:
My understanding is not the most technical but I've done some things like this myself.
Install a 0v banana jack on your stompbox build - use the part of the pcb that would normally be connected to the sleeve of the output 1/4" jack. Connecting this to the banana synth 0v jack will make the two circuits share the same 0v reference I believe.

Attenuation from the banana synth to the stompbox will probably suffice, however you may need to match impedance (with a transformer) if it's one of those funky fuzz circuits that is built to react to a guitar's tone and volume controls. If the idea is to send the audio out of the modular, into the processor, then back into the modular they also likely need an input preamp on the way back into the modular.

Audio signal can go via banana cable if that's what the synth offers as an output, just install banana jacks on the effect box i/o. But, different nana systems use different audio path connectors at different stages of the signal flow, banana, 1/4", 3.5mm, tinijacks etc. If you had the space on your enclosure you could include a couple of input/output jack formats if necessary.

Hope that's been some help!
Thank you very much for your input. You're pretty much confirming what I already believed to be true, and that is important in boosting my confidence before moving forward.

IMPEDANCE: I've already designed in impedance "matching" circuitry as well as level boosting circuitry into the overall circuit design. So I guess I'm good there.

I place quotes around the word "matching" since so many people take the phrase "impedance matching" to mean that both the output of one device and the input of another device must have impedance levels that are the same. That is to say, they take the word "match" to mean that the input and output impedance levels are equal. I know this to be 100% untrue, which is why I placed ~matching~ in quotation marks.

That said, I've taken measures to ~protect~ (so to speak) any fuzz circuits with impedance levels that allow the fuzz circuit to operate at it's optimum level of performance.

ZERO VOLT ... CHASSIS GROUND: Now, when you say "zero volt", do you mean chassis ground? The reason I ask is because typical 9vdc powered devices don't have a dedicated zero volt rail. Your use of that word also generates a question; when you mentioned zero volt of the synth do you actually mean the zero volt rail of the power supply of the synth or do you actually mean the chassis? I don't mean to point out you're wrong about anything, my questions are genuine and serious, and not sneaky/snarky nit picking ~I'm smart and you're not~ remarks. I know it could look that way so I feel it necessary to clarify my comments.

Meanwhile I'll look into more about how these particular synth systems ("banana") handle power distribution so I have a better understanding of the situation.

DESIGN CROSS CONSULTATION: I am building something for someone who is having a synth system custom built ... so while I am building this processor someone else is building a synth. Clearly it's best I contact the synth project builder so he and I can be sure to address any issues that may be produced when marrying what he is doing with what I am doing.

DEVELOPMENT:
Preliminary testing of the processor is 95% done. Since I do not own a synth of this ilk, I had to first develop a synth system to come as close as possible to the sounds/waveforms that will be used with the device before I could actually do any live testing of the processor's circuits. With that behind me, I've been able to work out the small but crucial details of the components required (caps, resistors which affect tone and compression). I'm at this place of making sure power and grounding details are addressed properly (hence this thread).

DESCRIPTION: It's a multi-circuit device which includes a band pass filter, a ring modulator, a custom EQ of my own design that I've used in many previous constructs, a "fuzz" circuit, a pair of opamp overdrives, a patch matrix which will consist of roughly a dozen in/out jacks ... banana jacks if I do my homework properly, all housed in a 12" x 8" aluminum enclosure with wooden endbells and unique lettering/graphics that are 100% hand done and very VERY permanent, powered by an external PSU with international travel capability. That's as detailed an explanation as I am willing to publicly publish for the time being.

Mr. Green
flts
Rex Coil 7 wrote:
ZERO VOLT ... CHASSIS GROUND: Now, when you say "zero volt", do you mean chassis ground? The reason I ask is because typical 9vdc powered devices don't have a dedicated zero volt rail. Your use of that word also generates a question; when you mentioned zero volt of the synth do you actually mean the zero volt rail of the power supply of the synth or do you actually mean the chassis?


I think the easy (if technically incomplete / iffy) answer here is "by 0V we mean the voltage levels that the signals generated by the respective devices are referenced to".

Eg. as you need device 2 to process signals from device 1, and then feed them back to device 1, both of the devices have to "agree" on what the 0V reference for the unbalanced signal is. As there is nothing between the two devices with a sleeve contact that would make the 0V connection automatically, that 0V has to be connected between the devices via a separate banana cable or other extra conductor.

As for what the stompbox and the synth consider their interpretation of zero volts is a different matter - I assume for the synth it may be something that is actually connected to mains earth, and with stompbox it may be a floating / virtual ground created by a voltage divider of some kind.

Edit: TL;DR: "by 0V here we mean whatever you would connect to the sleeves of all the jacks on in the devices" hihi
chrisdermo
Rex Coil 7 wrote:


ZERO VOLT ... CHASSIS GROUND: Now, when you say "zero volt", do you mean chassis ground? The reason I ask is because typical 9vdc powered devices don't have a dedicated zero volt rail. Your use of that word also generates a question; when you mentioned zero volt of the synth do you actually mean the zero volt rail of the power supply of the synth or do you actually mean the chassis? I don't mean to point out you're wrong about anything, my questions are genuine and serious, and not sneaky/snarky nit picking ~I'm smart and you're not~ remarks. I know it could look that way so I feel it necessary to clarify my comments.


Oh I just stopped calling it a ground socket after Tom Bugs said that was technically incorrect and it was actually a 0v reference socket to be shared between devices. My lack of technical knowledge fails me beyond that point.
https://www.muffwiggler.com/forum/viewtopic.php?t=194576&postdays=0&po storder=asc&start=74

Rex Coil 7 wrote:

DESCRIPTION: It's a multi-circuit device which includes a band pass filter, a ring modulator, a custom EQ of my own design that I've used in many previous constructs, a "fuzz" circuit, a pair of opamp overdrives, a patch matrix which will consist of roughly a dozen in/out jacks ... banana jacks if I do my homework properly, all housed in a 12" x 8" aluminum enclosure with wooden endbells and unique lettering/graphics that are 100% hand done and very VERY permanent, powered by an external PSU with international travel capability. That's as detailed an explanation as I am willing to publicly publish for the time being.

Mr. Green


I mean this sounds mind blowing. Looking forward to seeing the end result!
Rex Coil 7
flts wrote:
...Edit: TL;DR: "by 0V here we mean whatever you would connect to the sleeves of all the jacks on in the devices" hihi
Eloquently and clearly described. Perfect. Now I understand more of what I need to address as I move ahead.

Thank you! thumbs up

EDIT: Woops .... wait ... banana jacks don't use sleeves. So would it be safe to say "just connect the chassis of both the synth and the FX toy using a cable of whatever sorts fits the bill.."?

Hmmm ... I say ... would there be a small synth, stand alone perhaps, that could be used as a test bed or lab rat that I might use as a surrogate for testing out various notions of the processor before I actually design the processor in it's final form? Some small ~desktop~ incarnation of a self contained banana jack type synth of otherwise noisemaker to use in assisting my efforts? Even something in DIY form (buy the PCB and parts, enclosure, et al, and build a small banana jack synth that also emulates these Buchla-esque sounds for use as a test bed for further development of external processors?

If this project all ends up working out to my level of personal expectations, this order I'm filling may end up becoming a precursor (or inspiration) of something I may end up offering to those that use "these types of synths" (heavy emphasis on the word "may"). That said, a small example of one would be very useful for developing more processor systems for other users of these types of synths in the future.

Just for shits and giggles, here's an example of just one of my previous works .... it's a signal attenuator with a built in overdrive unit and dual FX loops for a vintage Hammond I designed and built for Roger Arrick (owner/operator of synthesizers.Com) a number of years ago.



I stopped producing devices on a large scale a few years ago since demand far outgrew my ability to keep up and long lead times created unfavorable reviews, most especially by mainstream consumers that have become spoiled by BIG RETAIL and their return policies and willingness to put up with unreasonable customer demands. In short, shit got cray cray and I bailed out. After 500+ units built/delivered I simply became tired of dealing with "consumers" and their shit slinging parties held in various groups. In the first four+ years 90% of my clientele were touring and/or recording pros (which were exactly whom I wanted to cater to). Once the mainstream consumer became aware of my devices things went downhill, and after being lied about and the subject of too many pitchfork and torch sessions I pulled the plug.

But due to a LOT of heavy encouragement from people I respect (such as the person I'm working for on this project as well as a number of others), over the last few months I've been reconsidering going back to very low levels of production. The production would be completely based on commissioned custom orders for those that understand my limits as a producer of one-off highly custom goods.

Well anyway, right now my focus is squarely on developing this device for one person's needs. The picture is more of a teaser of what's to come and what this particular project may end up looking like. Only quite a bit larger. And mo betta.

Geez. meh Talking WAY too much about this ... I'll shut up now. d'oh!
chrisdermo
Rex Coil 7 wrote:


Eloquently and clearly described. Perfect. Now I understand more of what I need to address as I move ahead.

Thank you! thumbs up

EDIT: Woops .... wait ... banana jacks don't use sleeves. So would it be safe to say "just connect the chassis of both the synth and the FX toy using a cable of whatever sorts fits the bill.."?


Say you're building a standard effects pedal, with a normal 1/4" jack I/O. In the place that the sleeve of that 1/4" jack would normally connect to the circuit, that's what you connect to your 0v banana socket. Or if you're building a synth with a standard minijack cv interface, in the place where the sleeve of a minijack would connect to the circuit - that's where you wire up your 0v banana jack. Then just use one nana cable to connect it to a 0v spot on any other hardware you want to be able to patch between and you're sorted.

Rex Coil 7 wrote:

Hmmm ... I say ... would there be a small synth, stand alone perhaps, that could be used as a test bed or lab rat that I might use as a surrogate for testing out various notions of the processor before I actually design the processor in it's final form? Some small ~desktop~ incarnation of a self contained banana jack type synth of otherwise noisemaker to use in assisting my efforts? Even something in DIY form (buy the PCB and parts, enclosure, et al, and build a small banana jack synth that also emulates these Buchla-esque sounds for use as a test bed for further development of external processors?


Ciat Lonbarde Tetrax / Lorre Mill Double Knot or Keyed Mosstone / Bugbrand Chirper or DRM2.
Maybe a Ciat Lonbarde Paper circuit?

All the different manufacturers use different voltage standards though seriously, i just don't get it
Rex Coil 7
Thank you very much Member *chrisdermo. thumbs up

You've been very helpful and have provided useful and easily understood information that will help me quite a bit.

nodnod spinning
chrisdermo
Rex Coil 7 wrote:
Thank you very much Member *chrisdermo. thumbs up

You've been very helpful and have provided useful and easily understood information that will help me quite a bit.

nodnod spinning


No problemo! Glad my limited knowledge of these things was helpful to someone else hihi
Rex Coil 7
Sadly, this project was cancelled. Customer ran into hard times. I feel really bad for him, it seems like the worst things happen to the best people.

(I am no longer monitoring this thread).
Rex Coil 7
Oh Happy Day!

I am thrilled to say this project is back on! The thing I am most happy about is that the client has been able to get back on his feet and is up and rolling again.

Ok, so I have been able to piece together a "fakester system" to be able to test the custom circuitry I've made up.





* Two Doepfer VCOs that have both hard sync and soft sync.
* Mutable Instruments WARPS.
* Doepfer Dual Ring Modulator.
* Happy Nerding FM-Aid.
* Intellijel uFoldII wavefolder.
* Intellijel Polaris multi-stage mondo gigafilter with phase shifter.

Aside from the controllers one would render a guess are plain-old x plain-old stuff ...

* Flight Of Harmony "Choices" unsprung 2ch joystick.
* SoundMachines Light Plane.
* 2 SoundMachines Light Strips.
* 61 note Dot Com kybd.
* Dual 20 inch 2ch ribbon controllers (3 channels each)
* Dot Com sprung joystick.
* Modified for modular use Ernie Ball VP Jr. 25K volume foot controller that I machined to accept Bourns B10K pot, replacing the stock A25K pot. It makes one hell of a bullet/bomb-proof foot controller that now matches the quality and design ethos of the rest of my rig.

I've also rec'd the aluminum enclosure (12" x 8" x 2.5") and the wooden end bells (DIY). All PCBs are on hand and ready to populate. Well, not quite ... some of those circuits can use a number of component variations, so that's where I am now ... working out what is going to sound best/work best with these folded/cross-faded/ring modded tones and sounds you fellas work with in this particular genre of synth. The client is like many folks that use these types of synths ... summed up = Fripp and Eno No Pussyfooting. I've actually still got my original vinyl copy of that album I bought in 1978 ... maybe 1979. So "I get it" .... well, a little at least.

oops oops oops

Anyhow .... we're on!!! I'm so happy for the client ... he's a really good person and I enjoy working for him. One of the better people I've crossed paths with in my 58 years of life ~n~ livin'.

Questions to follow, that is certain. Thanks so far for the help that has been provided. I'm a total square peg trying to fit into the round holes of these types of synths. Hang in there with me.

Thanks again, Rex.

EDIT: I see there is a "Rex" already in this subforum. That said, you may refer to me as RC7 ... or my given name, Brian.

Hasta Lasagne!!

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