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Why are lpg's not more popular in synthesizers? Virtual Instrument Plugins
Old 1 week ago
  #1
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Why are lpg's not more popular in synthesizers?

I really don't understand why low pass gates are not used in both poly and mono synth's more? The amount of sound design they enable seems to me to add so much deminsion and depth, I really don't get why they are so underutilized in designing synth's.. it seems like a no brainier, like looping envelopes have become, another huge sound designing tool hut yet so simple.
Old 1 week ago
  #2
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j3rk's Avatar
 

LPGs based on optocouplers (vactrols) aren't super easy to make reliably. They're simple circuits, but it's a lot of expense and labor to sort and match them up as they vary quite widely between batches and even within the same batch. I believe this is why MakeNoise stopped making the original QMMG module, because matching four per module for a one-man company was getting out of hand. Also, Excelitas (formerly Vactec, formerly Perkins/Elmer) stopped making them. There are a few audio companies making VTL and similar models again though, so that's good. You can also make your own, but those vary as widely or more than the originals.

I agree with you that the sound is great.

There are also some rather ridiculous laws outside the US now about the use of Cadmium, which is used in the LDR half of the vactrol. I think it's making it difficult to release new products in the EU using vactrols or LDRs.

There are ways to make LPGs using solid state parts (see things like the Natural Gate module). I'm actually working on something like this myself. These are a little cleaner, and more predictable, but it sounds very good to my ears. (check out the demo video for the Natural Gate for example) (pasted below)

I've thought about doing a poly using LPGs. It wouldn't be something that was easy to mass produce, but might be fun to build a couple of.

Old 1 week ago
  #3
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That does sound really good, it seems like even the solid state ones all have there own groove to them too.
Old 1 week ago
  #4
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BTByrd's Avatar
Probably because they don't fit with the standard subtractive monosynth paradigm. LPGs affect the harmonic content of a signal and its amplitude at the same time, so they take the place of both the filter and the VCA. Most users prefer having separate control over filtering and dynamics.

The good news is that there are a boatload of monosynths with patch points on the market, and a boatload of people making LPGs in different flavors. If you want a synth with a LPG, feel free to roll your own. And if you want a polysynth, run an E370 into a QMMG. Cop a Quadra or 2X Maths for modulation, and use Yarns for MIDI->CV.
Old 1 week ago
  #5
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You know I totally feel like I would rather have a lpg as well as a filter and four stage envelopes, I think there is room for all of it, allot of synth's are including fm, looping envelope, why not include that too? I know you can put one together with euro but I mean why don't companies put them in their synth's though?
Old 1 week ago
  #6
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I'm on the other side of things. I just don't get why people are so into LPGs, so maybe folks here can explain this to me (cause if I even put the question out there on some other forums I quickly find myself needing to duck flying tomatoes).

I get that when an LPG opens, it does so in terms of amplitude and timbre, and that this is closer to the behavior of natural instruments (though I thought half the fun of synths is not trying to imitate acoustic instruments). And I get that vactrols are kinda unpredictable and quirky and organic and have personalities and are cool in those senses.

But when I listen to demos like that above, I hear tons of very short percussive plucky sounds, but almost nothing else. Is it difficult to get an LPG to sustain? I realize they open and close so organically when pinged, but more so than a decently set envelope? Whenever I think of trying an LPG for something, I never do, because I imagine I will be limited to just plucks. I don't have much experience with these things (just sticking the toe into modular!), so I'm more than happy to be convinced otherwise, as its always nice to find an entire universe of sound you didn't realize existed.

But what's all the fuss about vactrols and LPGs, and why don't I tend to hear anything super cool in demos of them? Am I somehow missing what makes so many love them so much?
Old 1 week ago
  #7
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Moonwhistle's Avatar
 

Quote:
Originally Posted by fromthepuggle View Post
I'm on the other side of things. I just don't get why people are so into LPGs, so maybe folks here can explain this to me (cause if I even put the question out there on some other forums I quickly find myself needing to duck flying tomatoes).

I get that when an LPG opens, it does so in terms of amplitude and timbre, and that this is closer to the behavior of natural instruments (though I thought half the fun of synths is not trying to imitate acoustic instruments). And I get that vactrols are kinda unpredictable and quirky and organic and have personalities and are cool in those senses.

But when I listen to demos like that above, I hear tons of very short percussive plucky sounds, but almost nothing else. Is it difficult to get an LPG to sustain? I realize they open and close so organically when pinged, but more so than a decently set envelope? Whenever I think of trying an LPG for something, I never do, because I imagine I will be limited to just plucks. I don't have much experience with these things (just sticking the toe into modular!), so I'm more than happy to be convinced otherwise, as its always nice to find an entire universe of sound you didn't realize existed.

But what's all the fuss about vactrols and LPGs, and why don't I tend to hear anything super cool in demos of them? Am I somehow missing what makes so many love them so much?
Their forte is plucks but nice for a lot of things.

The fuss to me is people get really sick of standard subtractive with a filter and an LPG is a little bit of a revelation on the first try.

Just phone audio but here is the 0 Coast sounding like a nylon guitar morphing to banjo:



Really a basic sound but nice all the same.
Old 1 week ago
  #8
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Quote:
Originally Posted by fromthepuggle View Post
But when I listen to demos like that above, I hear tons of very short percussive plucky sounds, but almost nothing else. Is it difficult to get an LPG to sustain? I realize they open and close so organically when pinged, but more so than a decently set envelope? Whenever I think of trying an LPG for something, I never do, because I imagine I will be limited to just plucks.
Do you imagine low pass gates or have you used them?
You can send in whatever CV you like to control the gate. You can even send in an envelope to control the levels. Or ramps or audio (if you have a fast enough vactrol).
Essentially they are VCAs with filter characteristics that also have organic nonlinearties due to the nature of leds and opto couplers. You can use them to make filters, compressors, ping them. They are incredibly versatile and lifelike.

for a poly -- vermona perfoumer + quad LPG is rather nice.
Old 1 week ago
  #9
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BTByrd's Avatar
Not all LPGs are equally interesting. I find non-resonant LPGs kinda boring and mostly useful as plucky/dampened VCAs for percussion sounds. They don't function particularly well as filters... mostly just as VCAs. The natural slew of the vactrols does make for pleasant pings... classic Buchla bongotime. But resonant LPGs (usually) bring the filth. Brutal, screaming resonance. Nasty.

Using the Make Noise modules as examples, the Optomix is an example of the first type of LPG.



The MMG and QMMG are examples of the latter.



I have a QMMG and an Optomix. One of them gets way more use than the other. I'll let you guess which one.

But the general reason you don't see them on monosynths is that they weren't originally designed for use in classic "east coast" subtractive synthesizers, but rather to provide dynamics for complex/dual oscillators.
Old 1 week ago
  #10
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I've got a dual borg, that's the only 'filter' I have with vactrols and LPG abilities. I've listened and played with those functions (you can switch to 'normal' filter mode or use the vactrol modes which I believe turn it into a lpg), but haven't quite figured out what to do with them yet. I have yet to figure out quite what to do with these aspects of this module. I get what the filter aspects of it does, but how am I supposed to threat the lpg aspects differently?
Old 1 week ago
  #11
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Quote:
Originally Posted by j3rk View Post
LPGs based on optocouplers (vactrols) aren't super easy to make reliably. They're simple circuits, but it's a lot of expense and labor to sort and match them up as they vary quite widely between batches and even within the same batch. I believe this is why MakeNoise stopped making the original QMMG module, because matching four per module for a one-man company was getting out of hand. Also, Excelitas (formerly Vactec, formerly Perkins/Elmer) stopped making them. There are a few audio companies making VTL and similar models again though, so that's good. You can also make your own, but those vary as widely or more than the originals.

I agree with you that the sound is great.

There are also some rather ridiculous laws outside the US now about the use of Cadmium, which is used in the LDR half of the vactrol. I think it's making it difficult to release new products in the EU using vactrols or LDRs.

There are ways to make LPGs using solid state parts (see things like the Natural Gate module). I'm actually working on something like this myself. These are a little cleaner, and more predictable, but it sounds very good to my ears. (check out the demo video for the Natural Gate for example) (pasted below)

I've thought about doing a poly using LPGs. It wouldn't be something that was easy to mass produce, but might be fun to build a couple of.

[...]
Tricky to mass produce. Sounds like they're a prime target for digital emulation.
Old 1 week ago
  #12
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j3rk's Avatar
 

Quote:
Originally Posted by ToyBox View Post
Tricky to mass produce. Sounds like they're a prime target for digital emulation.
Check out the soft-synth Alto from Madrona Labs. It does a pretty good job of this. Still not quite like the physical counterpart, but definitely gets a good chunk of the sound.

Solid state gets close too, but you have to get the mix and curves right between the low pass and attenuation.
Old 1 week ago
  #13
I personally find they really are at their best at plucky percussive sounds. Not very useful in a polyphonic synth and not very versatile for a mono synth.
Funny thing is, no one really cared about them before the third wave of modular and the launch of Make Noise. The first wave being the late 60’s birth of modular synthesis, the second wave being the mid-90’s birth of Doepfer’s Eurorack
Old 1 week ago
  #14
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Quote:
Originally Posted by Kja View Post
You know I totally feel like I would rather have a lpg as well as a filter and four stage envelopes, I think there is room for all of it, allot of synth's are including fm, looping envelope, why not include that too? I know you can put one together with euro but I mean why don't companies put them in their synth's though?
They're just really obscure things.

Go back in time to when synths were making their way out of labs and universities into the hands of normal musicians. The "West coast" was on the experimental end, the "East coast" worked like your mouth and had keyboards you already kind of knew how to play and make music with.

People want to make music, more often than not music similar to the music they've heard and liked, so they want similar if not the same tools that was used to make that music, creating a feedback loop. There's a ridiculous amount of really popular music made with ADSRs and "East Cost" subtractive synths, so more such synths are made so that more people can make that kind of music.

I can't name you any chart topping LPG/"West Coast" using tune. They're possibly out there, I'm just not aware.

It's the very nerdy interests of various modular module makers that, very recently, brought back LPGs and the West Coast out of the dusty dark corners of synth history. I hadn't heard about LPGs altogether until the Eurorack boom of the past few years.

Anyway, point is if you want to see more LPGs in the mainstream, get Kanye West (or whoever's hot right now, I'm out of the loop) to use and brag about them. "LPGs and heartbreak"
Old 1 week ago
  #15
Gear Nut
 

I like lpgs for percussion. I want to like them more for other elements but rarely hear them jive well in a mix; often I hear them within more sparse tracks.

Maybe their character is lost on sustained parts in a mix with filtered layers?

Would love to hear songs where one is used non percussively and sits well in the mix.
Old 1 week ago
  #16
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I guess for me the fascination is that you can have a rythmic sound like the first video(that sounds great) and you can open it anytime to expose the wider sound. So you can create a cool sound them crunch it through a lpg and play it rythmically then you can open it more or close it more, it can create a super cool sound.
Old 1 week ago
  #17
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kaykaynotk's Avatar
 

I'm somewhat surprised I haven't seen them implemented in some fashion in inline volume/expression or as I guess they should be called 'loudness' pedals.

Maybe there is a guitar volume pedal out there that uses them? or at least one that tries to emulate the combined tonal and amplitude response vs CV level? The only ones I've ever come across are just a VCA.

Or maybe a Vactrol LPG wouldn't work like that?
Old 1 week ago
  #18
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Derp's Avatar
LPG's are super cheap in euroland. You can get the Meng Qi DPLPG for $60 and because it's passive, you wouldn't even need a power supply for it. Just pick that up and patch it into your synths.
Old 1 week ago
  #19
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j3rk's Avatar
 

Quote:
Originally Posted by ToyBox View Post
They're just really obscure things.

Go back in time to when synths were making their way out of labs and universities into the hands of normal musicians. The "West coast" was on the experimental end, the "East coast" worked like your mouth and had keyboards you already kind of knew how to play and make music with.

People want to make music, more often than not music similar to the music they've heard and liked, so they want similar if not the same tools that was used to make that music, creating a feedback loop. There's a ridiculous amount of really popular music made with ADSRs and "East Cost" subtractive synths, so more such synths are made so that more people can make that kind of music.

I can't name you any chart topping LPG/"West Coast" using tune. They're possibly out there, I'm just not aware.

It's the very nerdy interests of various modular module makers that, very recently, brought back LPGs and the West Coast out of the dusty dark corners of synth history. I hadn't heard about LPGs altogether until the Eurorack boom of the past few years.

Anyway, point is if you want to see more LPGs in the mainstream, get Kanye West (or whoever's hot right now, I'm out of the loop) to use and brag about them. "LPGs and heartbreak"
Chart topping and good are two different things.

That said, I hear you. They are/were pretty obscure. They started picking back up when Grant Richter (Wiard) started making his Borg filters, followed by MakeNoise.

They definitely don't just apply to plucked sounds, though obviously that's one of the big attractive points. If you want to hear them being used in slightly less experimental music, it's out there. Maybe look for something from Lyonel Bauchet for one example. They do make pretty good low pass filters in many cases. There are also some less-known LPGs that have improved resonance loops, that get away from that "thwappy overdriven" sound that some have. As well as other filter topologies made using vactrols (state variable for example).

I personally wouldn't want to use them for everything, but they're a lot more versatile than some would think. They also don't preclude having other filter types within the same system. In fact, if it was a solid-state setup, one could design one that could also be switched into other types of filters, then back into LPG mode, and it would work beautifully in a poly-synth.
Old 1 week ago
  #20
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Quote:
Originally Posted by ToyBox View Post
Tricky to mass produce. Sounds like they're a prime target for digital emulation.
LPGs are a part of the value proposition for Blocks in Reaktor 6.
Old 1 week ago
  #21
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mildheadwound's Avatar
I know people will get ‘triggered’, (those people always do!), when i mention this, but maybe it’s because sloppy filter/vca behaviour should hardly be considered a worthy addition? The simulated versions, (ie. mutable, and i think Natural Gate, mentioned previously), have more dynamic response, even though they are just emulated digital renditions.

Feed the same envelope into a filter and a vca at the same time, but with different attenuation gets you close enough. People are always talking about the ‘ringing’ sound with lpg’s, and perhaps its there, but so hardly noticeable, that i have to claim it as not much more then a romanticization, of a response curve, from a day where the options were much more limited.

Last edited by mildheadwound; 1 week ago at 08:26 PM.. Reason: Responsibilities
Old 1 week ago
  #22
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Barrage's Avatar
 

Quote:
Originally Posted by BTByrd View Post
Not all LPGs are equally interesting. I find non-resonant LPGs kinda boring and mostly useful as plucky/dampened VCAs for percussion sounds. They don't function particularly well as filters... mostly just as VCAs. The natural slew of the vactrols does make for pleasant pings... classic Buchla bongotime. But resonant LPGs (usually) bring the filth. Brutal, screaming resonance. Nasty.
oooh hooo, that sounds dirty. Almost makes me wanna buy and populate a eurorack.
Old 1 week ago
  #23
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j3rk's Avatar
 

Quote:
Originally Posted by mildheadwound View Post
I know people will get ‘triggered’, (those people always do!), when i mention this, but maybe it’s because sloppy filter/vca behaviour should hardly be considered a worthy addition? The simulated versions, (ie. mutable, and i think Natural Gate, mentioned previously), have more dynamic response, even though they are just emulated digital renditions.

Feed the same envelope into a filter and a vca at the same time, but with different attenuation gets you close enough. People are always talking about the ‘ringing’ sound with lpg’s, and perhaps its there, but so hardly noticeable, that i have to claim it as not much more then a romanticization, of a response curve, from a day where the options were much more limited.
You don't have to like the response or the sound, but this post shows a bit of a limited understanding, and most likely experience with any of this. Not triggered by your opinion of low pass gates, but this is silly. Because you personally don't care for or understand something, it can't be anything more than a romanticism.

There are loads of different vactrols. Different LED colors, different LDR dynamic ranges, different combinations which have vastly different speeds and shapes of responses. Even variation within the same line due to part tolerances.

In a forum where people like to call out the small variations in analog sound as the end-all be-all of synthesis, you'd think people would have a more open mind when it comes to a touch of unpredictability or sonic variation or another variety of timbre.

There is a time and place for precision. There is a time and place for imprecision. The coolest thing is that these can be mixed and matched at will in today's electronic instrument climate. But no... We should simply write off a whole technology as a myth because we personally don't see value in it.

Like I said, if it's not to your taste fine, but there are very audible differences in all of these forms of filter, VCA, combinations. They're quite real, quite demonstrable, and there are hundreds of examples out there to pull from, not to mention actually using all of them and forming a real opinion.

I actually don't use optocouplers much anymore myself, (for multiple reasons) but they are as valid an approach as anything else with upsides and downsides just like any component. You can exploit that, or choose something else. Pretending that it's all a myth is silly.

So, this doesn't have a very distinct and musically valid sound to you?



Or this?



Or...



Or... (bonus, 291 bandpass based on vactrols)





This one's always good.



Or, here's my own design with an adjustable ring... Just a self running patch on one of my systems, and nasty phone video/sound... It's pretty audible though...





You can do similar things with other combinations of functions. A good pinged and FMed State Variable filter for example (like the Serge VCFQ, ARP 1047, among others) will do nicely, but then you have to set up a whole patch around it. The optical gates just naturally produce a range of these sorts of sounds. You can go either way, or none of these ways at all if you like. Still, the distinction is real.

One last item:

Promotion existentielle singularisee | Lyonel Bauchet
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