How to check compatibilty of FX pedals with synth?

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Jee
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How to check compatibilty of FX pedals with synth?

Post by Jee »

Hi,
I know that guitar FX pedals have a different working level than synths (instrument level vs line level) but I've never been very clear about it... :hmm:
I purchased recently a Red Panda Particle V2 Delay that is flagged as "compatible with line level" but in practice I did get some nasty distortion with most of my synths unfortunately. I don't have any problem with my CXM1978 put in line level mode though.

I think the Particle pedal accepts up to +5Vpp at the input but that still seems a bit low for the hottest synths? I think modular is more like 10 to 20Vpp (so way too hot for guitar pedals) and +5Vpp is probably a regular line level (?) but some of my synths seem to exceed that output level (like my Grp A2 that I need to use at a level of 2 or 3 out of 10 graduation in the master volume to prevent clipping the pedal). Same with my RITM-2 that needs to be tamed down a lot (like max 1 third of the total volume) to prevent clipping. I find it pretty restrictive...

I didn't find the output Vpp of these synths in their respective manuals and i have no idea if my assumption is correct. Or maybe i missed something with the pedal setup? (doubt it though).

is there a way to check the Vpp output of a synth? Also it's not obvious with some manufacturers if the pedal is compatible or not, and i get lost with the impedances stuff... and also with the link with Vpp notion. So if someone can explain this to me in a comprehensive pragmatic manner so that I can more easily figure out if a pedal will work with my synths I would love it :)
Otherwise, is there a way to make my synths work at more decent levels and prevent clipping the pedal?
thanks
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Re: How to check compatibilty of FX pedals with synth?

Post by bphenix »

If they say line level, but don’t publish the spec, you are likely not going to get a large peak to peak range.

Here is a reference guide:
https://en.m.wikipedia.org/wiki/Line_level

As you see, that can be great exceeded depending on the synths or module so you’ll need to adjust.

In practice, it varies by manufacturer so you have read their spec sheets or ask them. More and more pedals consider synth use cases but unless they specify, you expect a lower peak to peak and only rarely will something be set for modular range since that type of design creates issues for the primary use cases. In general, certain types effects are more likely not to accept line level, for example overdrive, distortions, and compressors, so I recommend reading those spec sheets even more closely.
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PrimateSynthesis
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Re: How to check compatibilty of FX pedals with synth?

Post by PrimateSynthesis »

Jee wrote: Thu Jan 13, 2022 2:06 pm is there a way to check the Vpp output of a synth? Also it's not obvious with some manufacturers if the pedal is compatible or not, and i get lost with the impedances stuff... and also with the link with Vpp notion. So if someone can explain this to me in a comprehensive pragmatic manner so that I can more easily figure out if a pedal will work with my synths I would love it :)
Otherwise, is there a way to make my synths work at more decent levels and prevent clipping the pedal?
thanks
You can check the output of level of a synth with a level meter, oscilloscope, or a voltmeter set to AC.

Vpp is the voltage measured from peak to peak — the highest positive voltage to the lowest negative voltage.

I wouldn't be concerned with impedance if the source is a synth. Since the only important thing is that the output impedance is significantly lower than the input impedance, and if it's a synth it's going to be more than low enough.

The easiest way to prevent clipping is to turn down the input knob of the pedal or the output knob of the synth. Finding a nice range might require a bit of both.
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Jee
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Re: How to check compatibilty of FX pedals with synth?

Post by Jee »

Thanks for your replies guys.
I read the article but it's partly chinese to me. I mean that I don't exactly know what to do with it in respect of my concern.
Impedance doesn't seem to be the major issue indeed, so I can probably leave that aside for now. I might ask to the builder directly when not in the specs then.
Otherwise I can deal with it as it is as PrimateSynthesis says, I can just lower a lot the volume and it works, but I would have like to pick up pedals that would handle better the line levels... But i now understand that it's a bit of a technical issue for the pedal builders so even if they tend to provide "line level compliant" pedals more and more, i can see that somtimes it's a bit of lie / overstatement...

Could a passive DI box help with this? I understand it would drop the signal level and make it more compliant with the pedals (a bit like the opposite of a preamp somehow)?
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Re: How to check compatibilty of FX pedals with synth?

Post by Navs »

Jee wrote: Thu Jan 13, 2022 4:34 pm...
Could a passive DI box help with this? I understand it would drop the signal level and make it more compliant with the pedals (a bit like the opposite of a preamp somehow)?
I made a little passive 're-amp' box in the hope of addressing this issue, but to be honest, just lowering the volume level works as well for synths.

Other workarounds that people seem to use is running the synth to the pedal via an AUX on a mixer. But, in effect, all you're doing is lowering the level too.

You can get an inexpensive multimeter - highly recommended for general modular synth use anyway - but you may still have to re-adjust levels, e.g. your pad sound might be OK thru that phaser until you increase the resonance etc. etc. ...
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Re: How to check compatibilty of FX pedals with synth?

Post by a100user »

I use the AI006 which does the job nicely - no need to worry if compatible or not. There are other units that do this

https://aisynthesis.com/product/ai006-e ... x-adapter/
I'm looking for nothing at this moment in time
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PrimateSynthesis
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Re: How to check compatibilty of FX pedals with synth?

Post by PrimateSynthesis »

Jee wrote: Thu Jan 13, 2022 4:34 pm Could a passive DI box help with this? I understand it would drop the signal level and make it more compliant with the pedals (a bit like the opposite of a preamp somehow)?
It can. A passive DI takes uses a transformer to connect an unbalanced line level or instrument output to a balanced microphone input. They typically have a winding around 12:1. Which is used to not so much to reduce a line level signal to microphone level (which it does do), but to run a balanced cable from the stage to the mixing board to reduce noise. The other thing it does it multiply the input impedance around 130 times, so a bass would see around 200K from a 1.5K mic input. Which is way higher than a line input, but still a lower impedance than most instrument amplifiers — even lower if it's multed into an amp.

However you aren't trying to do either of those things, good transformers are expensive, and you would need an XLR to TS cable. And even the best transformers are not transparent. If you can solder, a much better way, in regards to both cost and sound quality, would be to build a little box with two jacks and two resistors. So with two 22K resistors it would divide the voltage by half, have the input resistance of a typical line-level input, and the output resistance of a typical electric guitar.
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Re: How to check compatibilty of FX pedals with synth?

Post by Jee »

Many thanks for the explanations !
It’s becoming slightly clearer. So basically it’s really more a question of voltage than impedance if I got it right. I’m very bad with physics :s
Anyway, I can’t solder but I know someone who can :hihi:
The build you suggest seems simple enough…

@a100user : this module seems neat but in my case it’s more about regular synth than the modular (I already have some cool FX in my case that are fine for me) so it won’t really cope with my need I guess.

It’s funny that no constructor built this simple resistor box to fix this common issue though :roll:
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Re: How to check compatibilty of FX pedals with synth?

Post by PrimateSynthesis »

Jee wrote: Fri Jan 14, 2022 5:20 pm It’s funny that no constructor built this simple resistor box to fix this common issue though :roll:
It likely because the volume knob on the synth and the input knob on the pedal are also voltage dividers, and usually enough to solve the problem.

One thing I forget to mention is that impedance can be a problem if you use a passive DI with a high-impedance input. For example, if the pedal was a Tube Screamer, the impedance would be 65M :eek:
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Re: How to check compatibilty of FX pedals with synth?

Post by Jee »

OK I see about the box, but I would make use of it if someone was to build one... just for ease of use.
No tube screamer in my pedal set, I use essentially delays and reverb in pedal format, that I find, overall, superior to eurorack ones. On the other hand I find eurorack distortion way better sounding and more versatile than pedals so i send my synths in the modular when I need serious distortions.
I'll probably see if my friend can build me the resistor box you mentioned, thanks for the tip ! ;)
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Re: How to check compatibilty of FX pedals with synth?

Post by Scories »

Navs wrote: Fri Jan 14, 2022 3:34 am Other workarounds that people seem to use is running the synth to the pedal via an AUX on a mixer. But, in effect, all you're doing is lowering the level too.
Does using a reamp box rather than a mixer insert makes a significative difference when using effect pedals with synths ?
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Re: How to check compatibilty of FX pedals with synth?

Post by Navs »

Scories wrote: Sat Jan 15, 2022 5:41 pm
Navs wrote: Fri Jan 14, 2022 3:34 am Other workarounds that people seem to use is running the synth to the pedal via an AUX on a mixer. But, in effect, all you're doing is lowering the level too.
Does using a reamp box rather than a mixer insert makes a significative difference when using effect pedals with synths ?
I think it depends on the circuit. I built the reamp box to make my synth 'look like' a guitar to interface with a fuzz pedal. Fuzz circuits can behave differently based on the impedance of the signal. So, in that case, yes - reamping protected the components from overloading/being damaged, and allowed the circuit to function as expected.
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Re: How to check compatibilty of FX pedals with synth?

Post by PrimateSynthesis »

Navs wrote: Sun Jan 16, 2022 3:07 am I think it depends on the circuit. I built the reamp box to make my synth 'look like' a guitar to interface with a fuzz pedal. Fuzz circuits can behave differently based on the impedance of the signal. So, in that case, yes - reamping protected the components from overloading/being damaged, and allowed the circuit to function as expected.
I'd say it's pretty much limited to current-starved amplifier fuzz pedals, as I'm not seeing how impedance would make a difference with big muff type fuzz pedals.
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Re: How to check compatibilty of FX pedals with synth?

Post by LB82 »

I gave up on trying to use pedals with line level sources, the gain staging routine you need to do is always bad.
I have better results using rack units or plug ins, even if they are more tedious to setup
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Re: How to check compatibilty of FX pedals with synth?

Post by Jee »

Well, I must say there is a frustrating aspect to it but in some circumstances, I getit to work fine...
I have only 3 pedals:
- Chase Bliss CXM 1978: used with a mixer send and Line input mode: never a clipping, works like a charm.
- Koma BD-101 delay: this thing can eat anything, even modular levels without problem. I use it for feedbacks along with my Vertice unit (and a +15Vpp output...): no problem.
- Red Panda Particle V2: clips with pretty much all my synths by default unless I use my synths at 20% of their max volume... and I still get clipping some time to time (resonance peaks mainly or in some resonant setups in the pedal). I find this pedal pretty creative but this bugs me a little. I hope to to get this little resistor box that PrimateSynthesis mentioned... my friend is looking into it :)
OR
I'll send a super hot output from vertice and totally melt the pedal input and see if it can make a good disto sound :hihi:
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