Does anyone know if it’s safe to run modular level outputs straight into the SQ-5, if the channels are padded? Thanks 
Hey @whatsoup,
Voltages on modular equipment can exceed the rating for the SQ inputs.
So whilst it is close (max SQ input = +30dBu = approx 10V peak to peak = majority of modular audio signals) we would not recommend it, and it’s the reason there are dedicated eurorack to line level and mixer modules.
Cheers!
Keith.
Thank you very much Keith for the quick response! I definitely won’t be chancing that one! Cheers
Necromancing this question…
I´m currently deciding between getting a second in-the-box mixer for Eurorack or use an SQ-5 for it´s obvious benefits. Still running a mixed setup, so I need to integrate line level from synths with Eurorack and vice versa. Ideally, I would be able to treat modules and synths as equal and have things routed back and forth via the SQ.
As I´m not a big fan of wasting half of the modular rack for IO modules (8-16 channels in and out to Eurorack), what are the options here?
A separate skiff for IO, holding just the conversion modules is one (costly) idea, but could grow incrementally as needed. What are the other options? Best practices?
At first I took Keith’s advice, then I realised it’s just INSANELY expensive to start mixing stuff in eurorack, and even then you’re lucky if it’s even half as functional as something like an SQ-5, so I started going into it ‘for now’. Everything seems fine. My padded SQ channels normally default to 8 gain, but i find myself putting the modular channels at -6 (obviously your mileage will vary), I’m also putting a the SQ compressors on max to be on the safe side.
I think the main concern is don’t blow your speakers? I have several failsafes in place, but you never know. Just be careful. Seems good to me, if I don’t forget to keep stuff turned down.
the way I read Keith’s answer was you could damage the SQ if the input voltage is too high
speakers are another issue. i wish someone could tell me why so many folks think louder is better.
I´m more concerned about routing signals back and forth between eurorack modular, traditional synths, outboard effects and DAW. In my case, it is studio only, so I don´t care about clipping too much. I just don´t want to fry the SQ-5 with an occasional unexpected voltage spike. Given that IO modules in Eurorack are not cheap, mono or stereo only and eat precious hp, isn´t there something like a transparent 8 or 16 ch limiter that I can just put in the rack below the SQ? I´m not an EE, so please be patient if my question is stupid.
@moebius
if it is in studio why clip ever?
why risk frying the SQ ??
you can raise the final in the DAW as much as you want.
why do so many people think louder is better ?
Oh, I don´t. Once in DAW, I can happily pump things up.
My main concern is that modular may spit out a voltage that may damage the SQ.
Example: Traditional patch, VCO to VCF to VCA. That filter will take away a lot of signal and should work without issues. But patching a signal from SQ Aux to some obscure modular FX unit may return something not as tame. Or let´s assume there is a filter somehow going into wild self-oscillation and straight back to the SQ. Worst case, you accidentally fat finger a patch in modular and send CV at full level to an SQ in. That´s where a constant +10V may arrive at the SQ until you find the right plug to pull. I´m just not sure if the SQ will handle that like a gentleman or throw some magic smoke at me.
Adding a few numbers to the discussion (kudos to 2thick4uni):
"While modular audio is typically 10v p-p, it can go as high as about 20v p-p.
-10 dBv (consumer line level) = 0.895v p-p
+4 dBu (pro line level) = 3.473v p-p
normal modular audio level = 10v p-p
peak modular audio level = 20v p-p
-10 dBv = -7.78 dBu
10v p-p = +13.2 dBu
20v p-p = +19.2 dBu"
I’m wondering, can you actually fry something with the voltage? I thought it was just loudness I had to worry about
like KeithJ AH said: YES you can ‘fry’ the SQ circuit components
louder is not better
dial it all back a ways from the 11+ you want to use
@volounteer No one said we want it loud, or what gains we want to use, that’s your assumption - I just want it to be safe. If simply turning the gain down is enough to not fry the circuit then that is good enough for me.
more gain == louder
louder == more gain
turn it down so the voltage could never get high enough to cause damage
if you are worried put a dummy load on the output and measure the voltage levels
then tape the knobs so they cant get moved to the right.
volounteer,
I think there is a misunderstanding. Our concern regarding damage to the SQ circuits is not there because we´re trying to feed it as hot as possible, gaining maximum loudness or whatever.
The reason is that a modular synth sometimes delivers unexpected results and may suddenly put out a much higher voltage than during normal use, see my examples above. You may accidentally patch a constant voltage into the audio path. The operator may have wanted to patch a CV signal to a CV in, but somehow ended up at the wrong audio path. A filter may go berserk by some unplanned modulation and so on.
The high levels are not created on purpose, they just may occur by user error. Under normal circumstances the signal will be tamed by VCA, VCF, mixers etc and be similar to any strong synth signal. It will stay at reasonable levels that the SQ can handle. Much like your average -10/+4 synth.
@moebius
then maybe you need to build a simple protective circuit so that any high unexpected voltage is clamped to a maximum safe level
and throw in a low pass filter to slow the higher freqs in the spikes to ensure the following zener or whatever works without problems
True, some kind of a limiter that can handle modular levels. I wonder if there are any DIY projects for that. Unfortunately, I´m still new with electronics, as you can obviously tell from my posts :). But I´m willing to learn and take your bulletpoints as a starting point for further research.
@moebius
i would ask why they made those levels so dangerously high in the first place
ask them if they have a way to ensure they are kept at a safe level to use with standard level gear from other companies
also you could probably find a smart HS nerd or an amateur radio operator or other person with the skill to build it for you
@volounteer Keith has already mentioned the solution, and it’s a line level module that sits in the eurorack case. this will attenuate the eurorack voltage making it safe to go into the mixer. But in eurorack land case space is precious and modules are expensive.
how much is a new SQ if you damage the old one
or how much are repairs and how long would that take and how much hassle
how much is a line level module for your rack?
which option is better considering the risk versus cost
The levels are just the norm in Eurorack land, like we have -10 in consumer devices and +4 in audio pro. In modular, these high levels are what all modules are built to.
Simple interfaces that are likely below the SQ´s quality are around 120-200 bucks for a stereo pair of IO.
Real good ones are more in the range of 300-450 per pair (like Vermona TAI-4 or ACL).
The bigger issue is space, as you have 2x104 hp for example, so 4 channels of IO would consume 30 of them. Worse for people going live with a skiff (small flat eurorack system), they often have just 104 or 84hp. That´s why I thought about an external converter. Could be a second skiff when using eurorack IO modules as the solution. Or something in pedal/DI box format (beware of spaghetti cabling outside the modular). Personally, I´d prefer something 19" based, so there is enough space to grow, no eurorack space is wasted and it´s still a clean setup.
I don´t know how much effort it would take to build something that works on SQ audio quality level and simply attenuates/boosts levels at a fixed rate, like the pad button found on mixers (and a fixed preamp for the other direction). I will see if I can find people and instructions in the DIY sections of the modular forums.