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Eurorack Modular Questions Part 2
Old 11th September 2012
  #1
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🎧 10 years
Eurorack Modular Questions Part 2

So instead of making a bunch of separate threads, I figured it'd be easier to just put all the remaining questions in one thread. This is basically the last bit of research on Eurorack. I'll be starting on 5U after this.

1. I'm thinking for Eurorack to use some of the stackable cable from Tiptop. Since my Eurorack plan has me starting out with a basic system (2 VCO, Filter, 2 LFO, 2 ADSR, Mixer, Multiple, VCA, ES-3) in a 3U Tiptop case and an additional Doepfer 32hp case. How many would you recommend I start out with and what lengths? (I wish they came in packages, but they are only available individually).

2. Can I get away with a simple VCA? Seems like the Doepfer A-131 is a good, inexpensive choice, with straight output control and the ability to take an envelope generator, but why are units like the intellijel uVCA or the MALEKKO VCA more expensive? is it just because they are dual VCA? Why would one need a dual VCA anyway? It seems to me that the VCA is the last step before outputting to your speakers (or AI) and to provide some type of master level control, so why would you need dual outputs?

3. Whats the difference between a Voltage Controlled LFO and just a plain old LFO? Seems like the Doepfer A-145 is virtually identical to the Doepfer A-147 save the former has a reverse sawtooth waveform and the later has the CV knob that allows you to control incoming modulation. Other than that, the only difference I can see is the 147 is "Voltage Controlled", but what does that mean practically?

4. Is a mixer a mixer a mixer? I wanted a mixer module primarily to control the level of the VCO's before sending them to the filter (although I can see other uses for it as well). So far I have modeled the Manhattan Analog Mix, just because it takes up so little space, but does the mixer really matter other than the number of in/out and knobs? (I haven't heard many people talk about Manhattan analog).

5. Buying: I've been mainly doing my pricing on analoguehaven (I'm in the US), but there are some other retailers that sell this stuff, one of which I have bought stuff before (Noisebug). Does it matter who I go with in terms of availability or service?
Old 11th September 2012
  #2
Gear Addict
 
🎧 10 years
1. I got 90 and have a 9U and a Cwejman S1, the more the better.

2. For everything you modulate, you can use another signal to modulate it's intensity f.e. vibrato, tremolo, loudness by velocity, envelope amount, etc. So if you want to atomate that, you need a vca.

3. You can modulate the pitch of the LFO with another LFO or by velocity for example. With the plain old LFO you have to do every modulation by hand.

4. You can mix a lot of things in a modular f.e. osc pre vcf, post vcf, different modulation sources, triggers, etc. You should not mix signals with multiples or stackables, because this can destroy inputs, to high voltages.

5. No.
Old 11th September 2012
  #3
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2 Reviews written
🎧 15 years
FWIW heh
1. hmmm I'd opt for a bigger case; the tiptop for the sequencer, tactile interface, etc, and then a 2 row 19" rack should be enough for a good sized synth. You don't have to fill it up rightaway. It's just that you're buying a PSU regardless of the size of the case, so might as well have a little more real estate with that.

2. the Intellijel µVCA (or uVCA) and the Malekko VCA are both 2 VCA in one package. The Malekko has a switch for linear/exponential, the Intellijel has a knob to change the response curve. (yes, compressors have something like that, hard or soft knee)
The Doepfer is a low cost single VCA (with multiple CV inputs). Older ones (if you buy secondhand) can be upgraded with a different opamp. The good thing about the Doepfer is that it does it's job quite well (especially on CV signals, has CV attenuators on the CV inputs (so you can set the amount of CV) and is economically priced.
Usually for the Logarithmic waveform of audio an exponential (or sometimes semi exponential) circuit is used, for CV it's most often linear. But no one says you can't use one for the other.
---
Aaah but you can never have enough VCAs
imagine you're sending an LFO to open a filter cutoff. But it's on a sound that has an envelope (AD or ADSR). So it'll sound better if you let the LFO follow the amplitude of the envelope. This can be done with the use of a VCA.

You have an oscillator, a filter, an LFO, one envelope, one multiple and 2 VCA.
First the audio path: let's keep it simple shall we?
oscillator->filter->VCA1->out
of course key/sequencer CV (pitch)->oscillator CV input
Now the volume control (amplitude) of the sound
key/sequencer gate->envelope->VCA1 cv input
Now the LFO goes into the filter cutoff. But you want to control it with the envelope as well, so you put the LFO output into the input of VCA2. And the envelope output (same one as the volume control) you multiply in the multiple and send to the VCA2 cv input.
The output of VCA2 you route to the CV input of the filter cutoff.

Now every time you hit a key the oscillator plays a note and the gate from your keyboard opens the amplifier of the oscillator, but also opens the LFO-ed filter cutoff following the same volume envelope.
---
The modules you can see as building blocks. A VCA is a way to combine different building blocks and create a more complex sound. If you want a "natural sound" it's nice to have some very subtle modulation options through clean, fast VCAs to approach timbres on a clarinet, or flute or whatever sound you need, or you can go for a modulation-fest, the moment you hit a key all hell breaks loose.

IMO ppl. get too hung up about special (and expensive) modules, while an oscillator, a bunch of good VCA, a pair of LFO, a pair of good snappy envelopes, and maybe a resonant filter, ringmod and waveshaper is a very flexible tool with which you can make a wide range of different sounds. the trick is to combine it in useful ways. (read the sticky with all the synth examples) For example; no one said you can't bandpass a CV signal (going to the cutoff of your filter, or into the CV input of the waveshaper). CV signals can be treated like audio, and vise versa. Audio mostly AC (-5V to +5V), so you'll need a little rectifier to flip the negative part of the waveform to the positve side, and turn it into CV (0 to +5V). The a-119 has that. However... you can use a module to "shift" the whole waveform up, so it's lowest point is now above 0V (if the amplitude was ranging from -5 to +5 it'll now be 0 to +10V). So this is a manipulation of the electric signal (shifting it on the Y axis) without changing the amplitude (difference between low and high point of that wave)) This is called "offset"; look, for an example at the a-183-2 or the Manhattan Analog CVP.

I hope this makes a bit of sense to you. Look in the sticky. Pictures tell more than a thousand words.
To summarise; you can never have enough VCAs, but also don't skimp on modulation sources and modifiers (envelope, ringmod, waveshaper, bitcrusher, S&H etc.)
I'd suggest you get at least the dual VCA. i'd even say get 4 VCA, or 6 of em.

3. The VCLFO has the frequency on a CV input. So, that's the same as a CV input on an oscillator, for the pitch control. Since the LFO is low frequency, instead of pitch, you'll hear wubwubwub wub..... wub.........wub....wub..wubwubwub...wub........wub...... etc. if you feed the CV input of the VCLFO a sine wave.
the normal LFO has a pot to set the frequency, and that's it.

So imagine using one LFO, and two envelopes, and one VCLFO and a bunch of VCA on your sound.
Feedback loops are possible, because it's analogue and there's no noticable delay (electricity = speed of light) and no poor resolution (stepping).

4. Yes that's possible. That mixer has attennuators that lower the volume (amplitude) of the sound. and then offer the possibillity to combine that VCO with an external sound, or another output (different waveform) of the same VCO. Or perhaps to mix a filtered output of the same VCO with an unfiltered one? etc. Mixers are useful building blocks (NEVER use a multiple as a mixer). Tip: get one for audio (minus infinity to 0V) and one that also has negative voltages (sometimes called attenuverters (Fonitronik) or "polarising mixer" (Doepfer) (-the name depends on the manufacturer) so you can offset CV signals also in the downwards range (and voltage control this of course !). Another thing is mixer/panners: mix two signals (or one signal and 0V) into one output. Or one input into two (left right) outputs with one control. That's another VCA for ya.
There's also seperate attenuators (Malekko 8NU8R which has a diode distortion built in to generate interesting timbres). And Attenuverters without mixer (a-133).
confused yet? heh

Manhattan Analog is a USA brand that ppl. seem to be very happy with. I can't give you first hand info about the mixer, since I haven't used it. I do have a couple CVP as kits but I haven't built it yet, waiting for parts.

FWIW I'm now replacing some of my mixers for VCmixers. (which are 4 VCAs with a mixer) But ordinairy mixers are fine, if you have a little more room in your case. (real estate and simple building blocks vs high density functional modules? - different concepts - different prices as well)

5. I haven't heard anything bad from ppl. that bought at Noisebug or Nova Music (they have some Pittsburgh now). But I've shopped new stuff with Shawn at AH, and Schneidersbuero in Berlin. Shawn has a wide variety and excellent service. Prices are roughly the same everywhere. So take your pick, the bad seeds have worked themselves out of the market by now, either is fine) Some modules are very expensive new, and some are the same price as secondhand almost (if it's a popular, rare module in new condition). But roughly rule of thumb is 70-80% of price new for secondhand.

In the modular planner, under the Doepfer page, or in the Doepfer module page on Doepfer.de, everything is grouped into functionality. Have a look at that, then reference the Doepfer manuals of those modules, there's good examples and pictures in there as well. That'll clear up some basic concepts for you. It's a bit easier to start with than the Sound on Sound thing, which dives in the deep end fairly quick after a brief introduction.
I'll leave you with a link to another thread: https://gearspace.com/board/electron...l-voltage.html
Old 11th September 2012
  #4
m.o
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Some tips from doepfer-guy here

VCA:
If you're looking at doepfer VCAs you should definatly get the dual VCA 132-3.
You get 2 VCAs in one module with the added bonus that they can be switched between linear or exponential response curves.
As I think was said above, the A-132-1 is 'low cost' VCA, which means it works fine with CV, but it's not recommended for audio (unless you want to dirty it up )

Mixer:
The Pittsburgh mixer is quite nice and has the added bonus that you can use it as 4 independent Attenuators (i.e. dampen the signal going into it).
The Doepfer A-138 mixers (at least the A/B the difference is the curve response to the pots Linear/Exponential - or CV / Audio) models have the extra feature that if you don't patch anything into the top (#1) input then that knob will act as a variable voltage source (handy for offsetting things).
Old 12th September 2012 | Show parent
  #5
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atma's Avatar
 
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you remember the infamous "conference" scene in cronenberg's scanners?
Old 12th September 2012 | Show parent
  #6
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Quote:
Originally Posted by m.o ➡️
Some tips from doepfer-guy here

VCA:
If you're looking at doepfer VCAs you should definatly get the dual VCA 132-3.
You get 2 VCAs in one module with the added bonus that they can be switched between linear or exponential response curves.

Mixer:
The Pittsburgh mixer is quite nice and has the added bonus that you can use it as 4 independent Attenuators
Both are excellent recommendations. I'd suggest those two exact modules for any starter Euro system. The Intellijel uVCA has a couple of slight advantages (continuous curve shaping, and smaller by 2 hp), but the Doepfer 132-3 is a rock solid choice for both audio and CV.

As for voltage-controlled LFOs, well, voltage-controlled anything is one of the main reasons to buy a modular instead of a pre-wired synth. That plus using VCAs to modulate CV, that's how you can get some complex and continuously evolving patches going.
Old 12th September 2012
  #7
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LFOing your LFOs is so great for complex modulations. I suppose it depends on your goals though.

Used Doepfer to start with, at the very least for the learning experience, is the way to go, unless you are flush with disposable income and if you are now you might not be if you're one of the unfortunates to become part of the eurocrack epidemic.
Old 12th September 2012 | Show parent
  #8
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i'm about to put together a little eurorack shortly, and reading all these bits and pieces makes me so excited. there are so many facets that i'd never even thought of (or imagined possible—since a lot of these things simply don't apply to non-modular synthesis), and it makes me absolutely ecstatic at the idea of the freedom you gain from a modular rig.

and that's something that's really bothered me, in a creative sense, for a long time—feeling constrained by prefabricated synthesizer architecture and not being able to do exactly what i want to do. i think i've finally stepped in the direction that will start to allow me that freedom. i don't know why i didn't seriously consider it sooner.

(oh yeah, money).

i'm a little bemused by the concept of audio and control voltage signals being somewhat interchangeable on some level. is there an article somewhere that would break it down simply?
Old 12th September 2012
  #9
Gear Head
 
🎧 5 years
Couple of things not covered above:
2. Dual VCA's are also good if you want to do stereo (or correlated dual mono or something).
3. I have both a 145 and a 147. I very rarely use the VC option in the 147 - it's cool for really complex stuff but not particularly useful on a day-to-day basis. I use the L/M/H rocker on the 145 a lot, though - the different ranges give you more delicate control in each range. There are advantages to both, though.
Old 12th September 2012 | Show parent
  #10
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Quote:
Originally Posted by atma ➡️
i'm a little bemused by the concept of audio and control voltage signals being somewhat interchangeable on some level. is there an article somewhere that would break it down simply?
You can just think of them as the same really. Voltage is voltage. So the main thing that defines "audio" is that it oscillates within the frequency range that we can hear (roughly 20 cycles per second up to 20,000). But that doesn't prevent you from using those audio-range signals as CV to modulate something.

There's no difference between a 100Hz square wave being produced by module designated as an Oscillator when compared to a 100Hz square wave coming from an LFO module. You can hear that LFO as audio if it goes up into high enough frequency ranges. And you can use that oscillator to modulate things as CV. The only difference from a design point of view between those modules is that the oscillator should track a keyboard/MIDI-CV so you can play accurate notes with it, while the LFO might not act that way (though some actually do).
Old 12th September 2012 | Show parent
  #11
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right, but i have a very strong understanding of audio signals from a technical point of view, so i can easily utilize and manipulate them to achieve whatever task at hand. i have no concept of what's technically going on with control voltage, so i subsequently have no grasp of how they'd be used as audio, or how audio would be used as CV. I mean, if i have a signal comprised of an oscillator being frequency-modulated in the audible spectrum, which is being run through a bandpass filter with high resonance.. that means nothing to me in terms of what it could potentially do if it were used as CV. see what i mean? i guess maybe if i had some experience listening to, and analyzing CV signals with an oscilloscope, i'd perhaps have a better grasp, but i have no idea.
Old 12th September 2012
  #12
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2 Reviews written
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atma, did you check the link https://gearspace.com/board/electron...l-voltage.html
also please check the sticky? there's a lot of articles in there!
Old 12th September 2012 | Show parent
  #13
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Thanks for the detailed response. This actually help a lot.

Quote:
Originally Posted by Reptil ➡️
FWIW heh
1. hmmm I'd opt for a bigger case; the tiptop for the sequencer, tactile interface, etc, and then a 2 row 19" rack should be enough for a good sized synth. You don't have to fill it up rightaway. It's just that you're buying a PSU regardless of the size of the case, so might as well have a little more real estate with that.
Yeah, I was thinking about that, but I may not have much room for anything bigger at the moment. I may have to settle for a Tiptop HE 3U with a Doepfer 32hp beauty case, at least for now. It kind of depends on some outside factors right now. In any case, if I can work a larger case, it'd probably have to be something like a monorocket Base90.

Actually I had a question about the monorocket base90, if someone knows or owns one. The photo on the big city music page looks like its shallower than the one on the monorocket home page.

BigCityMusic:


monorocket page:


Does anyone know which one is right and what the dimensions of the case are? That would really help as I cannot seem to find any information about how deep the case is or which one of these is correct.



Quote:
Originally Posted by Reptil ➡️
...
I hope this makes a bit of sense to you. Look in the sticky. Pictures tell more than a thousand words...
To summarise; you can never have enough VCAs, but also don't skimp on modulation sources and modifiers (envelope, ringmod, waveshaper, bitcrusher, S&H etc.)
I'd suggest you get at least the dual VCA. i'd even say get 4 VCA, or 6 of em.
Yes, this does make sense. I was thinking of the VCA as just a simple output volume control at the end of the signal chain. While it is that, it can also be all those other things you described. I'll definitely put in a dual VCA for starters in the Eurorack model.

Quote:
Originally Posted by Reptil ➡️
3. The VCLFO has the frequency on a CV input. So, that's the same as a CV input on an oscillator, for the pitch control. Since the LFO is low frequency, instead of pitch, you'll hear wubwubwub wub..... wub.........wub....wub..wubwubwub...wub........wub...... etc. if you feed the CV input of the VCLFO a sine wave.
the normal LFO has a pot to set the frequency, and that's it.

So imagine using one LFO, and two envelopes, and one VCLFO and a bunch of VCA on your sound.
Feedback loops are possible, because it's analogue and there's no noticable delay (electricity = speed of light) and no poor resolution (stepping).
Ahh, yes, OK I missed that little (important) detail. 147 it is then, as I want to have the option to control the Frequency of the LFO, especially from the ES-3.


Quote:
Originally Posted by Reptil ➡️
4. Yes that's possible. That mixer has attennuators that lower the volume (amplitude) of the sound. ...
OK, this makes sense. I think I'll follow the advice of m.o here and get the Pittsburgh Mixer instead of the Manhattan Analog one. Seems like its a bit more featured and worth the extra hp.

Quote:
Originally Posted by Reptil ➡️
5. I haven't heard anything bad from ppl. that bought at Noisebug or Nova Music (they have some Pittsburgh now). But I've shopped new stuff with Shawn at AH, and Schneidersbuero in Berlin. Shawn has a wide variety and excellent service. Prices are roughly the same everywhere. So take your pick, the bad seeds have worked themselves out of the market by now, either is fine) Some modules are very expensive new, and some are the same price as secondhand almost (if it's a popular, rare module in new condition). But roughly rule of thumb is 70-80% of price new for secondhand.
OK, great. I haven't found a whole lot on the used market, but I am only looking on eBay. Once I get ready to make a decision, I'll start scouring the used markets more closely, but since I'm still in the planning stages ( and not yet at a final decision yet), there seems little point in perusing the used markets just yet.

Quote:
Originally Posted by Reptil ➡️
In the modular planner, under the Doepfer page, or in the Doepfer module page on Doepfer.de, everything is grouped into functionality. Have a look at that, then reference the Doepfer manuals of those modules, there's good examples and pictures in there as well. That'll clear up some basic concepts for you. It's a bit easier to start with than the Sound on Sound thing, which dives in the deep end fairly quick after a brief introduction.
Yep, I have a few different configurations on the modular planner right now. Handy little tool.

Quote:
Originally Posted by Reptil ➡️
I'll leave you with a link to another thread: https://gearspace.com/board/electron...l-voltage.html
Nice, thanks.


Quote:
Originally Posted by triplizard ➡️
3. I have both a 145 and a 147. I very rarely use the VC option in the 147 - it's cool for really complex stuff but not particularly useful on a day-to-day basis. I use the L/M/H rocker on the 145 a lot, though - the different ranges give you more delicate control in each range. There are advantages to both, though.
The other thing about this is that since I'm planning on getting the ES-3, I've been recommended before that I can also use the LFO's in the Voice Controller, especially when perfect DAW sync is needed. Or I may get both LFO's, but I definitely want to be able to modulate the freq from an external source.
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