Euro CV to expression pedal input

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subdo
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Euro CV to expression pedal input

Post by subdo »

I'm about to pull the trigger on a Strymon Big Sky and wondering about using eurorack CV (Maths, URA, etc.) to modulate values via the expression pedal input. Do I really need something like the ALM S.B.G? I realize there is a range issue i.e. Strymon takes +0/5v and Maths puts out +/-10v but it seems like that could be handled by a simple attenuverter. Can I do any real damage to the pedal experimenting?
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Post by wigwig »

You can find some discussion about this in the forum.

I asked Strymon the same question about the Big Sky and was told that excessive voltage might cause damage.
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Post by richc90 »

Strymon said in some other thread (about clocked delays, I think) that all their pedals with the appropriate EXP input can be controlled with external CV via a TRS connection with a range of 0-5V into EXP.
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Post by jwm »

i use the sbg with my el cap all the time (with the 5V output)
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Post by subdo »

Thanks. So what do you do about the R in the TRS connection since euro patch cables are just TS. Going on this link the ring has the reference voltage?

http://www.strymon.net/strymon-tech-cor ... ion-pedal/
In electronic terms, this is most commonly accomplished with a TRS (tip / ring / sleeve) 1/4″ cable where the reference voltage is on the “ring,” the control voltage is fed back to the device on the “tip” and the “sleeve” is ground.
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Post by jwm »

the sbg actually includes a floating ring cable for this exact use..

this one from expert sleepers should work too..
http://www.analoguehaven.com/expertslee ... torcables/
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Post by subdo »

jwm wrote:the sbg actually includes a floating ring cable for this exact use..

this one from expert sleepers should work too..
http://www.analoguehaven.com/expertslee ... torcables/
Looks like the SBG is the best way to do this. Thanks again.
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Post by Artaos »

There is an amazing trick for doing this safely, and without an extra module (just using a regular linear VCA):

- patch a stackable in BOTH VCA input and VCA output (yes...)
- patch from your expression pedal input to either end of the stackable
- CV in the VCA is your CV control over the pedal

No idea how this even works, but it does. Works perfectly with my Eventide Space. It's safe because whatever CV you apply, the expression input will only go from 0% to 100% according to the pedal (i.e. no over voltage is possible)
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Post by mattb »

I do not have a Strymon Big Sky but I am using an Insert cable with my Earthquaker and Chase Bliss pedals to control them with my modular
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Post by Paranormal Patroler »

Artaos wrote:There is an amazing trick for doing this safely, and without an extra module (just using a regular linear VCA):

- patch a stackable in BOTH VCA input and VCA output (yes...)
- patch from your expression pedal input to either end of the stackable
- CV in the VCA is your CV control over the pedal

No idea how this even works, but it does. Works perfectly with my Eventide Space. It's safe because whatever CV you apply, the expression input will only go from 0% to 100% according to the pedal (i.e. no over voltage is possible)
This. Umcorps even has a video showcasing this with a Space pedal.
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Post by ignatius »

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Post by Leverkusen »

Looks like it's more the other way round, doesn't it? :hmm:
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Post by moegl »

Leverkusen wrote:
Looks like it's more the other way round, doesn't it? :hmm:
depends on what ADDAC means by "Invert switch for inverting the expression pedal action." ?
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Post by subdo »

Artaos wrote:There is an amazing trick for doing this safely, and without an extra module (just using a regular linear VCA):

- patch a stackable in BOTH VCA input and VCA output (yes...)
- patch from your expression pedal input to either end of the stackable
- CV in the VCA is your CV control over the pedal

No idea how this even works, but it does. Works perfectly with my Eventide Space. It's safe because whatever CV you apply, the expression input will only go from 0% to 100% according to the pedal (i.e. no over voltage is possible)
I'm trying to figure how this works.

What do you do about the TRS issue? One of those floating ring cables?
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Post by subdo »

Leverkusen wrote:
Looks like it's more the other way round, doesn't it? :hmm:
Yeah, I read the descriptions on these and they are expression pedal to euro CV. Still useful but not what I'm looking for here.
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Post by Paranormal Patroler »

subdo wrote:What do you do about the TRS issue? One of those floating ring cables?
I think you need to make a DIY Y-cable, from 2 x TS to 1 x TRS. Check Umcorpo's video and look for some other threads in the forum, this thing comes up every now and then.

I plan on using a direct cable to the Deco input, which accepts 5V. Just use an attenuator and make sure it stays within range.
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Post by subdo »

Paranormal Patroler wrote:
subdo wrote:What do you do about the TRS issue? One of those floating ring cables?
I think you need to make a DIY Y-cable, from 2 x TS to 1 x TRS. Check Umcorpo's video and look for some other threads in the forum, this thing comes up every now and then.

I plan on using a direct cable to the Deco input, which accepts 5V. Just use an attenuator and make sure it stays within range.
I actually have one of those I got with the QuNexus. So if the CV signal is on the tip what do you plug the other cable into (i.e. the ring)?
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Post by Paranormal Patroler »

subdo wrote:
Paranormal Patroler wrote:
subdo wrote:What do you do about the TRS issue? One of those floating ring cables?
I think you need to make a DIY Y-cable, from 2 x TS to 1 x TRS. Check Umcorpo's video and look for some other threads in the forum, this thing comes up every now and then.

I plan on using a direct cable to the Deco input, which accepts 5V. Just use an attenuator and make sure it stays within range.
I actually have one of those I got with the QuNexus. So if the CV signal is on the tip what do you plug the other cable into (i.e. the ring)?
Nope, you got it wrong. The Y cable is for the VCA trick: TRS to pedal, TS to VCA Input, TS to VCA Output and CV controls how much your VCA opens (re: VCA CV control).

If you want to use CV directly with the pedal I think you only need a TS to TS cable. I assume that's what people use but I haven't done it myself so do it at your own risk.
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Post by Artaos »

subdo wrote:
Artaos wrote:There is an amazing trick for doing this safely, and without an extra module (just using a regular linear VCA):

- patch a stackable in BOTH VCA input and VCA output (yes...)
- patch from your expression pedal input to either end of the stackable
- CV in the VCA is your CV control over the pedal

No idea how this even works, but it does. Works perfectly with my Eventide Space. It's safe because whatever CV you apply, the expression input will only go from 0% to 100% according to the pedal (i.e. no over voltage is possible)
I'm trying to figure how this works.

What do you do about the TRS issue? One of those floating ring cables?
Haha, I stopped trying to figure out how it works. It works very well though, and seems very safe, you get CV only over the voltage the pedal accepts.

About the TRS issue, I just use a 1/4" TS cable to 3.5mm TS cable. It works just fine with my Eventide Space. It might depend on the pedal though. YMMV. If you really want to, you can use a floating ring cable, or a TRS to TS+TR splitter.
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Post by ignatius »

Leverkusen wrote:
Looks like it's more the other way round, doesn't it? :hmm:

whoops.. lol.. doh!! :oops:
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Re:

Post by xidnpnlss »

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Re:

Post by xidnpnlss »

Paranormal Patroler wrote: Wed Nov 23, 2016 7:47 am
subdo wrote:What do you do about the TRS issue? One of those floating ring cables?
I think you need to make a DIY Y-cable, from 2 x TS to 1 x TRS. Check Umcorpo's video and look for some other threads in the forum, this thing comes up every now and then.

I plan on using a direct cable to the Deco input, which accepts 5V. Just use an attenuator and make sure it stays within range.
Hi. Sorry to necro. Did you ever do this with your Deco? How did it work out? I'm thinking of doing this with my Deco too.

Since this post, is there any gizmo that ensures one won't go over 5v?
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Re: Re:

Post by ersatzplanet »

xidnpnlss wrote: Mon Mar 01, 2021 10:39 am
Paranormal Patroler wrote: Wed Nov 23, 2016 7:47 am
subdo wrote:What do you do about the TRS issue? One of those floating ring cables?
I think you need to make a DIY Y-cable, from 2 x TS to 1 x TRS. Check Umcorpo's video and look for some other threads in the forum, this thing comes up every now and then.

I plan on using a direct cable to the Deco input, which accepts 5V. Just use an attenuator and make sure it stays within range.
Hi. Sorry to necro. Did you ever do this with your Deco? How did it work out? I'm thinking of doing this with my Deco too.

Since this post, is there any gizmo that ensures one won't go over 5v?
I'm thinking of doing this for my Nord Modulars and using a Vactrol to make sure it doesn't get over voltage. The expression pedal jacks themselves provide the voltage that is modulated by the pot in the pedal. Just replace the pot in the schematic with a Vactrol (or FSR as an alternative) and it will never do over voltage. A simple transistor circuit will also work if you want faster response than the Vactrol will give. If you just modulate the voltage already provided by the expression jack, you will never blow up the piece being controlled (you may blow out the Vactrol or transistor of course).
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