So explain to me: CV vs Expression

[Dark Barn]

My main question is why do CV inputs accept expression control but Expression inputs do not work with CV?

Furthermore why is CV then not the standard if it works with inputs from both types of sources? Is it a cost or difficulty constraint?

Finally is it possible/difficult to convert a CV signal to an Expression pot value with like magic, or gerbils?

Help a CV noob out!

[sonidero]

Different companies use different Voltage Variances... Some are +/- 10 or 8 or 5... If you have the correct Voltage something putting out CV should work with an EXP in... An Expression Pedal is just a pot varying the Voltage... It's all the Same...

[Dark Barn]

Ok, the source of my confusion is that Taylor from Iron Ether suggests to not use CV into the Exp jack on the Xerograph, that it can harm the pedal. Is it really just a matter of tuning the correct voltage to be compatible with it?

[sonidero]

Ask him what the Voltage is... There is a chart online for the different companies and YES too much could damage it... The Moog CP-251 has a Lag which varies the Voltage Output and so does the MP-201...

[Astricii]

Think of it as Active Vs. Passive.

Expression is just replacing or adding a second resistance source(Pot) in series with the original pot.

CV or Control Voltage is actually sending an AC signal out. so yeah if you have discrete components that aren't supposed to have a voltage applied to them CV can fuck your shit up.

[autopilot]

+1 astricii.

CV is super awesome. It depends on the circuit, sometimes the parameter wont respond to voltage changes (connecting 2 points of a circuit, sweeping cap values, etc), yeah it could be modified to do it via cv (but it will mean extra circuitry, not space left, added cost, etc). Like sonidero said also there are different versions of CV (0-5, 0-8, 0-10, bipolar cv), and needs extra filtering because there could be some bleed via the reference ground (when using fast external lfo's), and there's a higher risk of potential damage plugging a non compatible source (wrong connection reference points, higher voltage). While with expression is a bit more safer.

The advantage is that with cv is more universal, because everything is setup to the same voltage, while with expressions the values varies a lot (some pedals need 10k, other 100k, other 50k, 500k, if is ts or trs). My favourite part with cv is that with trs jack you can control 2 parameters* (and 4 if you use on of those midi jacks) (if its wired that way*), while with exp just one parameter per jack. And you could route, feed everything together, from the same source (for example you could set up to increase the ring mod mix, ring mod freq, filter cutoff from one source and all of them be synced)

I did some controllers one is a cv splitter and other expression splitter, so i can feed one expression, sequencer or lfo and have 2 cv outs and 3 expression outs all in sync, so i can control multiple devices at once.

[excane]

Just to add... there has never EVER been any form of industry standard for CV.

Even Moog (pioneers in so many ways) have different CV values among products.

[Dark Barn]

Ok so, I'm looking at a few products that are standalone LFO generators to manipulate either CV or Exp ins on some of my devices. So far I've looked at:

Moog MP-201
Moog CP-251
Copilot FX Broadcast

Is there anything else I should look at in this category? Right now I'd like to stay clear of euro rack module stuff. If there's a small mono-synth with good LFO manipulation capabilities and +0/5 CV out that is worth looking at let me know about that too.

[univalve]

Brutal SPAM:
Flame clockwork
I' m selling mine.

[kosta]

Clockwork is fuuuuun.

[Deltaphoenix]

Not a controller but these seem neat.
http://guyatone.com/NewsSpotlight.php

I got a MP-201 recently so I am investigating some other CV controlled pedals, of course the Moogerfoogers are awesome.

[Deltaphoenix]

Is there anything else I should look at in this category? Right now I'd like to stay clear of euro rack module stuff. If there's a small mono-synth with good LFO manipulation capabilities and +0/5 CV out that is worth looking at let me know about that too.

Do you mean a small mono synth just for LFO manipulation capibilities and the CV?

I will say there is a dude on TB that did go the Euro Rack route, he used a pitch-to-voltage module, suppposedly with good results. I am not ready to get into Euro Crack but I may try to figure out if I used that one module, could I drive a Minitaur with it?

[Dark Barn]

I'd use the synth as well but yeah I'd be interested if it could send it's LFO.

[kosta]

The Moog CP-251 is worth it for the LFO alone if you can find one for a good used price. Very handy to have a good sample & hold generator at your fingertips, plus it outputs square and sawtooth waves and it can output and mix all three at once. Add to that the attenuation and lag processing on that unit and you can basically make any wave you could imagine and control the speed of it all with an expression pedal or another LFO. It's a bad little dude.

Most synths only give you gate and pitch outputs for some reason.