Random*Source Resonant Equalizer... or?

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SavageMessiah
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Re: Random*Source Resonant Equalizer... or?

Post by SavageMessiah » Thu Jun 11, 2020 6:40 pm

Not sure. The description for mine reads 'I build these modules with the highest input gain possible and a Burr Brown 2604 chip controlling the gain circuit - that makes the module very versatile - You have a lot of gain on tap (both inputs) - the right one is slightly (just a tad) hotter than the left one.' I don't know enough about these sorts of things to say whether Burr Brown chip is important to the amount of gain.

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Re: Random*Source Resonant Equalizer... or?

Post by natureclubcassettes » Thu Jun 11, 2020 9:28 pm

Pulled the trigger and got mine built this week, will be in the post tomorrow. So excited for this one!

Can anyone share more experiences with pinging the module?

SavageMessiah, who built your module?

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Biom
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Re: Random*Source Resonant Equalizer... or?

Post by Biom » Fri Jun 12, 2020 3:45 am

luketeaford wrote:
Fri Jun 05, 2020 1:00 pm
it gets very wild with feedback and one band's setting will affect everything else more than you might think. If the two lowest bands start to self-oscillate it can totally mask the other high bands and then backing off the lows can leave you with ear splitting 11KHz feedback (NOT fun).
It's a bit of an art to master it, needs time and practice, same as with other Serge modules, but possible.

Regarding the cv, absolutely agree. Serge wasn't the person to leave his modules with missing features.

From all EQ's I've used it's simply the best. Would also consider having a different caps version, if that makes a lot of sense, which I'm still not so sure about.

@natureclubcassettes Nothing unusual, compared to your average pinging. Just feed it with triggers.

@SavageMessiah I'm no tech, but these Burr Browns are a bit of a standard these days, when it comes to a lot of good clean gain. If it affected the price, then I'm not sure in it's effectiveness, if not - you're good having them!
Personally, I can't hear any difference between my $200 OTA vca and a "super fancy op-amps/chips" $400 vca and not that I didn't want to!

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Re: Random*Source Resonant Equalizer... or?

Post by klick » Fri Jun 12, 2020 4:37 am

desolationjones wrote:
Thu Jun 11, 2020 1:54 pm
Nice. Mine will only saturate a bit on the inputs. Now I wish I had more gain on tap... wonder if it's a simple resistor mod?
yes, it's a simple resistor, from the build documentation :

Code: Select all

Resistors RG1 and RG2 set the maximum gain level of each of the two inputs. 100k will make the
input knobs pure attenuators, i.e. full CW is 100% of the input signal (unity gain). 75k will allow a
maximum amplification of +33% (100k/75k = 133.3%), i.e. unity gain will be at around 2 o’clock
position of the knob. Similarly, 68k will allow a maximum amplification of +47%. Depending on the
input signal’s level, this can be used to add distortion / clipping before entering the EQ. How that
distortion will occur (and sound) depends on the op-amp used - that’s the one above RG1 in the
picture above. The OPA2604 has a nice clipping behavior.
the opa shoudln't change the amplification, only the sound of the clipping. 75k resistors are already great, will change it for 68k to get a tad more boost, as it's lovely sounding already, and I expect more juiciness out of it.

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Re: Random*Source Resonant Equalizer... or?

Post by desolationjones » Fri Jun 12, 2020 8:23 am

I just inspected mine and they are already 68k :oops: I guess the clipping behavior of these OPA's is so nice that I never considered it to be "distortion".

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Re: Random*Source Resonant Equalizer... or?

Post by SavageMessiah » Fri Jun 12, 2020 6:10 pm

natureclubcassettes wrote:
Thu Jun 11, 2020 9:28 pm
SavageMessiah, who built your module?
https://reverb.com/shop/gear-pile-deals

To be clear, this a module they built and listed, not a build I requested. It took forever to get here because it probably got stuck in a warehouse waiting for space on a plane during the worst of the coronavirus shutdowns.
Biom wrote:
Fri Jun 12, 2020 3:45 am
@SavageMessiah I'm no tech, but these Burr Browns are a bit of a standard these days, when it comes to a lot of good clean gain. If it affected the price, then I'm not sure in it's effectiveness, if not - you're good having them!
Personally, I can't hear any difference between my $200 OTA vca and a "super fancy op-amps/chips" $400 vca and not that I didn't want to!
Price was pretty much the same as other Resonant EQ builds I've seen on reverb.

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Re: Random*Source Resonant Equalizer... or?

Post by thetwlo » Sat Jun 13, 2020 1:13 am

Biom wrote:
Fri Jun 12, 2020 3:45 am

@SavageMessiah I'm no tech, but these Burr Browns are a bit of a standard these days, when it comes to a lot of good clean gain. If it affected the price, then I'm not sure in it's effectiveness,
Not really, at least in modules, Burr Brown chips can be 10-100x the cost vs.TL07x.
L-1 and Random*Source are the only ones I can think of that use them. WMD uses better op amps in some things, but not BB. For the most part everyone uses TL07x or TL08x. That is the standard.
Which makes a good argument for DIY, that price difference- 30 cents vs. $4 per chip is a huge deal to a manufacturer making a hundred +, but if you are building one module it's 4 or 8 bucks.

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Re: Random*Source Resonant Equalizer... or?

Post by Biom » Sun Jun 14, 2020 6:17 am

thetwlo wrote:
Sat Jun 13, 2020 1:13 am
L-1 and Random*Source are the only ones I can think of that use them.
I also heard a lot of mention in the hi-fi domain, guitar pedals, etc, but not trying to argue at all!
Have you noticed any difference between the chips you mentioned and the BB's? Is there a reason to use them?

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Re: Random*Source Resonant Equalizer... or?

Post by WMDevices » Sun Jun 14, 2020 10:35 am

thetwlo wrote:
Sat Jun 13, 2020 1:13 am
Biom wrote:
Fri Jun 12, 2020 3:45 am

@SavageMessiah I'm no tech, but these Burr Browns are a bit of a standard these days, when it comes to a lot of good clean gain. If it affected the price, then I'm not sure in it's effectiveness,
Not really, at least in modules, Burr Brown chips can be 10-100x the cost vs.TL07x.
L-1 and Random*Source are the only ones I can think of that use them. WMD uses better op amps in some things, but not BB. For the most part everyone uses TL07x or TL08x. That is the standard.
Which makes a good argument for DIY, that price difference- 30 cents vs. $4 per chip is a huge deal to a manufacturer making a hundred +, but if you are building one module it's 4 or 8 bucks.
Burr Brown was absorbed by Texas Instruments in 2000. They still produce the OPA parts, and are developing new OPA series parts, which are typically better and cheaper than the old Burr Brown stuff, but the Burr Brown name has been mostly dropped on newer tech. The newer parts are not usually available in through-hole packages, because SMT is far superior for building electronics efficiently, so TI doesn't even bother making newer parts in DIP packages. Look at the OPA1678, it's cheap and has great specifications.

Opamp specs are hotly debated in pro audio, where low signal performance and gain and noise are very important. In synthesis, the signals are much hotter, so gain and noise are not as important. TL0x are entirely suitable for many applications. For us to use a part that's more expensive than another part, we need a really compelling reason that has to be engineered. Mixer summing, high gain in a compressor, guaranteed low offset buffer, VCA that can handle 23vPP, CODEC output stage? Yeah definitely places for the right high end part. But for a lot of generic CV duties, TL0x are ideal.
Check out the growing number of WMD Demo Videos | WMD Website

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Re: Random*Source Resonant Equalizer... or?

Post by mfaraday » Sun Jun 14, 2020 3:24 pm

the res eq will ping, but you have to play with it. that really goes with any serge module - what you get out is much more a question of playing with it and using your ears rather than robotic patching. to ping, patch a trigger into the input and play with the feedback and band settings until it gives a satisfying ping.

raising and lowering a single individual band will change the sound in many ways - not as simple as you might think. the res eq is really a whole interconnected ecosystem, and, especially with feedback, expresses lots of satisfying nonlinearities. any one knob movement is unpredictable enough that i really think it benefits from no CV - having CV would almost make the module less interesting than it is (not to mention the price and size bulk of adding 10 VCAs...). the fumana, addac, and verbos bark are great filters for that kind of 'spectral shaping', but none impart as much character as the res eq in my experience.

i've built 4 at this point and i wouldn't worry too much about the caps... they will change the flavor, but not so much that it's worth driving yourself nuts over. the styrene caps that are often used are really great.

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Re: Random*Source Resonant Equalizer... or?

Post by natureclubcassettes » Sun Jun 14, 2020 6:57 pm

mfaraday wrote:
Sun Jun 14, 2020 3:24 pm
the res eq will ping, but you have to play with it. that really goes with any serge module - what you get out is much more a question of playing with it and using your ears rather than robotic patching. to ping, patch a trigger into the input and play with the feedback and band settings until it gives a satisfying ping.

raising and lowering a single individual band will change the sound in many ways - not as simple as you might think. the res eq is really a whole interconnected ecosystem, and, especially with feedback, expresses lots of satisfying nonlinearities. any one knob movement is unpredictable enough that i really think it benefits from no CV - having CV would almost make the module less interesting than it is (not to mention the price and size bulk of adding 10 VCAs...). the fumana, addac, and verbos bark are great filters for that kind of 'spectral shaping', but none impart as much character as the res eq in my experience.

i've built 4 at this point and i wouldn't worry too much about the caps... they will change the flavor, but not so much that it's worth driving yourself nuts over. the styrene caps that are often used are really great.
This is great to hear, and sort of what I imagined in terms of the resonant bands have a lot of influence over each other with lots of feedback engaged. Mine arrives tomorrow and I can't wait to try pinging it. If I send a VCO from a really snappy enveloped VCA into input one and a trigger into input two, will the resonant feedback pings be tuned to the sequence that the VCO is tracking?

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Re: Random*Source Resonant Equalizer... or?

Post by Biom » Mon Jun 15, 2020 7:58 am

What you mean by "pinging" is, in fact, a feedback within a resonant filter. The more resonance is involved, the more "ringing" or "pinging" you hear. This resonant peak depends on the frequency of the filter, as it is created at the edge of the slope (on top of it) and sometimes breaks into a self-oscillation (depending on a circuit). Working with high resonances sometimes needs practice, as you're dealing with formants, becoming dominant, no matter the initial signal frequency you were running through a filter.
If you want to tune your pinging to a certain frequency, you should do this by adjusting the frequency of the filter.

ResEQ is the same, but has more variables, which makes its tuning harder/longer. If you ever did the no-input mixing, you'll get the idea.
From my observations, it is truly possible to tune this module to some desired frequencies, but to a very limited extent, of course, and definitely nowhere near your expectations. I hate to tell this, but this is just an EQ in the end.

@WMD: Thank you for a professional read! Your approach seems 100% logical. The "hi-fi" modules is the last thing we need, I think.

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Re: Random*Source Resonant Equalizer... or?

Post by natureclubcassettes » Mon Jun 15, 2020 8:20 am

thanks for the detailed reply, Biom. I had no plans to tune the bands perfectly to a desired frequency, just wanted to be able to send a short tuned signal into it with a trigger in the other channel for short, almost tuned percussive sounds. It has always been a part of the Serge ecosystem I was really attracted to.

I guess this is "just an EQ in the end" if most EQs you encounter respond to trigger sources and offer resonant feedback... I already do a lot of feedback patching and thought it would be a really versatile tool in sculpting the timbre of a feedback loop, or for use in physical modeling with noise sources and LPGs and filters with variable Q. Guess I'll find out today.

Thanks again, and I'd love others to chime in with their thoughts on the ResEQ since they've lived with it in their system for a while.

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Re: Random*Source Resonant Equalizer... or?

Post by pelang » Mon Jun 15, 2020 8:36 am

natureclubcassettes wrote:
Mon Jun 15, 2020 8:20 am

Thanks again, and I'd love others to chime in with their thoughts on the ResEQ since they've lived with it in their system for a while.
My ResEQ is almost hardwired before the OTO Bam (reverb)

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Re: Random*Source Resonant Equalizer... or?

Post by daphnid » Mon Jun 15, 2020 10:18 am

Yeah ResEQ into reverb is great. I had one on loan for a few months until I got my Benjolin and, like ^pelang^, it was pretty much married to the Erbe Verb. What a wicked pair, it just sounded like the craziest amp feedback, or like an electroacoustic/Stockhausen performance. Esp when you modulate the shit out of the Erbe Verb. Perfect for dark EBM textures.

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Re: Random*Source Resonant Equalizer... or?

Post by Biom » Tue Jun 16, 2020 5:25 am

natureclubcassettes wrote:
Mon Jun 15, 2020 8:20 am
if most EQs you encounter respond to trigger sources and offer resonant feedback...
A lot of the "pre-musical" gear of the 50s responds to triggers and resonates quite nice. I believe, many ideas are brought from there. My point was just not to forget the primary purpose of such modules. In Serge universe that happens quite often. I see a lot of people use USGs as oscillators, which sometimes works and sometimes becomes absurd.
Here's what happens to a melody line, being overwhelmed by the EQ:
Lots of new harmonics, unrelated to initial melody.

Regarding the feedback loops, yes, eq's, filters and waveshapers are well-recommended.
Personally, I believe, an eq is as important within a modular, as an oscillator, no matter if it's resonant or not. Its among the most important basic blocks of every system to me. I use ResEQ as an "oscillator" a lot less often than as an eq. What I'd recommend, though, is to adjust it just at the edge of oscillation - makes the timbre more "acoustic" and "full"

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Re: Random*Source Resonant Equalizer... or?

Post by marwatt » Thu Jun 18, 2020 2:49 pm

WMDevices wrote:
Sun Jun 14, 2020 10:35 am
thetwlo wrote:
Sat Jun 13, 2020 1:13 am
Biom wrote:
Fri Jun 12, 2020 3:45 am

@SavageMessiah I'm no tech, but these Burr Browns are a bit of a standard these days, when it comes to a lot of good clean gain. If it affected the price, then I'm not sure in it's effectiveness,
Not really, at least in modules, Burr Brown chips can be 10-100x the cost vs.TL07x.
L-1 and Random*Source are the only ones I can think of that use them. WMD uses better op amps in some things, but not BB. For the most part everyone uses TL07x or TL08x. That is the standard.
Which makes a good argument for DIY, that price difference- 30 cents vs. $4 per chip is a huge deal to a manufacturer making a hundred +, but if you are building one module it's 4 or 8 bucks.
Burr Brown was absorbed by Texas Instruments in 2000. They still produce the OPA parts, and are developing new OPA series parts, which are typically better and cheaper than the old Burr Brown stuff, but the Burr Brown name has been mostly dropped on newer tech. The newer parts are not usually available in through-hole packages, because SMT is far superior for building electronics efficiently, so TI doesn't even bother making newer parts in DIP packages. Look at the OPA1678, it's cheap and has great specifications.

Opamp specs are hotly debated in pro audio, where low signal performance and gain and noise are very important. In synthesis, the signals are much hotter, so gain and noise are not as important. TL0x are entirely suitable for many applications. For us to use a part that's more expensive than another part, we need a really compelling reason that has to be engineered. Mixer summing, high gain in a compressor, guaranteed low offset buffer, VCA that can handle 23vPP, CODEC output stage? Yeah definitely places for the right high end part. But for a lot of generic CV duties, TL0x are ideal.
hi all
I believe that it must be taken into account that if the circuit was designed 30 years ago (or more) it is not sufficient to change opamps for better "performance".
Surely the OPA are "technically" light years ahead compared to the tl072 but "perhaps" are, unnecessarily, too performing for this circuit ... maybe then one must be careful that the circuit does not auto-oscillate (due to the huge bandwidth) and things like this ... is there so much difference to justify the use of OPA vs TL0xx? what do you think?

marwatt

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Re: Random*Source Resonant Equalizer... or?

Post by klick » Thu Jun 18, 2020 2:55 pm

just an idea of something it is really great at :

- feed any material into it (gate, rythmical or not, or audio, whatever).
- Adjust the bands, and feedback, until you get a total meltdown, there is really ways to keep it under control, and not over clipping.
- feed the nice texture of previous step, into a vca, then into a ping pong delay, with a bit of spring reverb at the end.
I can spend the night with just this :)

any variation is welcome, sometimes clouds can really shine with it too, spectral mode madness !


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Re: Random*Source Resonant Equalizer... or?

Post by natureclubcassettes » Sat Jun 20, 2020 12:42 pm

@luketeaford waiting for you to chime in here! Love your work.

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Re: Random*Source Resonant Equalizer... or?

Post by Biom » Mon Jun 22, 2020 1:02 pm

marwatt wrote:
Thu Jun 18, 2020 2:49 pm
hi all
I believe that it must be taken into account that if the circuit was designed 30 years ago (or more) it is not sufficient to change opamps for better "performance".
Surely the OPA are "technically" light years ahead compared to the tl072 but "perhaps" are, unnecessarily, too performing for this circuit ... maybe then one must be careful that the circuit does not auto-oscillate (due to the huge bandwidth) and things like this ... is there so much difference to justify the use of OPA vs TL0xx? what do you think?

marwatt
Looking forward to someone answering this question either. Although, WMD has already made a great point.

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Re: Random*Source Resonant Equalizer... or?

Post by natureclubcassettes » Mon Jun 22, 2020 3:28 pm

Just wanted to mention how special this thing sounds with harmonically complex sounds; I've been sending it 2-op FM sounds from Rings and it just shines.

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Re: Random*Source Resonant Equalizer... or?

Post by novim » Mon Jun 22, 2020 6:47 pm

Just a note about opamps. I built the R*S version using OPAs and IIRC they draw about twice as much power as TL072s. When there are ten it adds up. I learned this from the datasheets after filling out a small case with the Res EQ, whereupon the Row Power 30 started blinking out on the +12v rail. I had to draft in a little Frequency Central PSU and dedicate it to the Res EQ.

There was a discussion about the Res EQ and opamps in the Serge Facebook group and some notable Serge people voiced a strong preference for the TL072s, for what it's worth. I can't speak from experience, but I have a CGS 202 partly built and I'm going to give them a try and compare the two.

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Re: Random*Source Resonant Equalizer... or?

Post by felt body » Mon Jun 22, 2020 11:01 pm

Just reiterating everyone saying how special this module is: I tend to feed any mono source into it just to give it a bit more rust and grit, even with all the bands at noon. There's something special about what it does to the audio!
A quick question: how does everyone handle using the different outs? Sometimes it seems like the comb filter outs can make a really wide stereo signal, but it must depend on the source because this doesn't always happen.
And does anyone have any interesting / clever patching tips for utilising the two regular outputs, which (I think??) are identical?

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Re: Random*Source Resonant Equalizer... or?

Post by Biom » Tue Jun 23, 2020 2:48 pm

Regular are good for plain stereo, whereas combs should be hardwired to the x-fade or stereo vca's

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