Lopass gate

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snoop
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Lopass gate

Post by snoop » Tue Feb 09, 2010 4:23 pm

Hi!

Been trying to get hold of a single or double lopass gate(s), ready made module, but no luck yet. Is there anyone who makes them in 5U (Motm, .com, or modcan connectors). Tried bridechamber but no luck yet.

Not that familiar with lopass gates. But i suspect this module would be great for making percussion sounds?

Best,
Roger

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essex sound lab
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Post by essex sound lab » Tue Feb 09, 2010 4:30 pm

Cynthia made a limited run of them in Dotcom format. I don't know if she has plans to do it again...might be worth asking.

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Post by snoop » Tue Feb 09, 2010 4:36 pm

Ok, thanks. Mailed cynthia

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Post by snoop » Tue Feb 09, 2010 4:49 pm

Seems the Cynthia one is without resonance. But they have a production run with modules ready in about one month. I been looking at some youtube videos and the ones with resonance seems more usable to me

Roger

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Post by dude » Tue Feb 09, 2010 4:52 pm

a doepfer beauty case never hurt anybody... :twisted:

sandyb

Post by sandyb » Tue Feb 09, 2010 4:56 pm

the only resonant 5U low pass gate i know of was the diy one. pcbs are sold out it would appear (which is maybe why you've had no luck with bridechamber):
http://www.naturalrhythmmusic.com/lopass.html
the cynthia one is fairly good - especially if you run a couple together. i've never felt the need for resonance in an lpg. you could always patch it though if you end up with one that doesn't have it built in.

sandy

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Post by essex sound lab » Tue Feb 09, 2010 5:00 pm

sandyb wrote: the cynthia one is fairly good - especially if you run a couple together. i've never felt the need for resonance in an lpg. you could always patch it though if you end up with one that doesn't have it built in.
I find Cynthia's Quad LPG to be more than adequate, but I must admit I'm no West Coast aficionado.

sandyb

Post by sandyb » Tue Feb 09, 2010 5:07 pm

essex sound lab wrote:
sandyb wrote: the cynthia one is fairly good - especially if you run a couple together. i've never felt the need for resonance in an lpg. you could always patch it though if you end up with one that doesn't have it built in.
I find Cynthia's Quad LPG to be more than adequate, but I must admit I'm no West Coast aficionado.
they're absolutely fine lpgs no doubt. i have some plan b ones in my euro system. i prefer them to the cynthia lpgs a bit although they were both afaik designed by the same person. the plan b have a bit more ring and woodiness about them to my ears anyway. the cynthia ones ring pretty well for that classic lpg sound but i find they need hitting with a pretty sharp envelope to do so, certainly more so than the plan b.
imho, ymmv etc...

sandy :)

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Post by Peake » Tue Feb 09, 2010 5:26 pm

essex sound lab wrote:
sandyb wrote: the cynthia one is fairly good - especially if you run a couple together. i've never felt the need for resonance in an lpg. you could always patch it though if you end up with one that doesn't have it built in.
I find Cynthia's Quad LPG to be more than adequate, but I must admit I'm no West Coast aficionado.
There is a bit of brassiness in it not occuring in the Buchla. And I believe that there is naturally a bit of resonance in the circuit.
This is not the place I'd imagined it to be.

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Post by snoop » Wed Feb 10, 2010 1:08 pm

Just bought one from thomas white. Anyone have opinions on using dual vactrol or 2 x single vactrol? Any difference? He could make it anyway i wanted it

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Post by Peake » Wed Feb 10, 2010 1:11 pm

Two single vactrols may have slight differences in response as there are two light elements involved instead of one, but all things are possible..

I don't know if I've ever seen it described. A dual vactrol is a single light source and a pair of receiving elements, correct?
This is not the place I'd imagined it to be.

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Post by snoop » Wed Feb 10, 2010 1:59 pm

Ehhh... personally i have no idea how these things are built. Just know that i like the sound. Gonna use it for percussion sound, specially fast percussion. So wondered what would be the best option and if there is a difference. Have heard very nice wooden sounds, and wet tamblalike sounds from these things

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Post by doctorvague » Wed Feb 10, 2010 3:00 pm

Peake wrote:Two single vactrols may have slight differences in response as there are two light elements involved instead of one, but all things are possible..

I don't know if I've ever seen it described. A dual vactrol is a single light source and a pair of receiving elements, correct?
Yeah a dual one has the same LED but 2 photosensors in the same pkg. Vactrols vary a lot one to the next, I'm not sure technically why that is, but they do. I can attest to that after measuring some. Plus there are different types made with different materials that have widely varying response/recovery times, curves and different on and off resistances. It's reasonably a deep rabbit hole once you start down it.

I think of all the LPG variations I've heard demos of I gotta hand it to the QMMG for the most organic woody tone. Just one guy's opinion. I've thought about re-paneling one of those in 5U more than once...
Thomas White's sounds great too. Certain classic designs like this- it would be nice to be able to re-panel easily. In other words if the QMMG guy (sorry don't know the name) would sell a populated board that you could slap behind a dotcom or MOTM panel or whatever. Seems like something like that would sell, but what do I know. Maybe most of those kinds of DIY'rs already have the Thomas White one. Just a thought.

I had the Cynthia LPG and sold it. It just didn't do anything for me but maybe I wasn't using it right or something. I seem to recall STG saying that they wanted to see 10V vs the usual 5V to really make them sing.

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Post by bwhittington » Wed Feb 10, 2010 3:28 pm

essex sound lab wrote:Cynthia made a limited run of them in Dotcom format. I don't know if she has plans to do it again...might be worth asking.
For what little it's worth, Cynthia told me she was out of the LPG business a few months ago, because of all the competing products. It doesn't hurt to ask, of course.

Cheers,
Brian

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Post by J3RK » Wed Feb 10, 2010 4:51 pm

dude wrote:a doepfer beauty case never hurt anybody... :twisted:
I don't know... One may have... I know this guy....

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Post by doctorvague » Wed Feb 10, 2010 5:18 pm

J3RK wrote:
dude wrote:a doepfer beauty case never hurt anybody... :twisted:
I don't know... One may have... I know this guy....
hurl anything hard enough

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Post by thermionicjunky » Wed Feb 10, 2010 7:40 pm

doctorvague wrote: I think of all the LPG variations I've heard demos of I gotta hand it to the QMMG for the most organic woody tone. Just one guy's opinion. I've thought about re-paneling one of those in 5U more than once...
Thomas White's sounds great too. Certain classic designs like this- it would be nice to be able to re-panel easily. In other words if the QMMG guy (sorry don't know the name) would sell a populated board that you could slap behind a dotcom or MOTM panel or whatever. Seems like something like that would sell, but what do I know. Maybe most of those kinds of DIY'rs already have the Thomas White one. Just a thought.
Yeah, I have my heart set on the QMMG, but I would prefer to limit my Euro expansion to things that would be too much of a pain in the ass to convert. It's the VC damping that sold me. It appears to employ a panel component board connected to a main board with headers and Tony told me when it first came out that it should run well on +-15v. I would love to see the main board for sale.

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Post by Peake » Fri Feb 12, 2010 5:44 pm

Thanks doctorvague. So the answer would be, use a dual vactrol if you want (probably) tighter, more closely-matched performance, and two singles if you want/don't mind potential variation.

IIRC, the three VCAs on my old Buchla 212 module all sounded slightly different. You find which one is best for filtration, for VCA work, and go with it.

Yes, the vactrols do need a large voltage to get ringing. I don't have one to test right now but IIRC the Buchla envelopes put out 15V signals (I'm probably wrong). If you apply a smaller signal, it slews significantly. Try a sample and hold output and see that very large, sharp changes are unslewed, and what happens to the smaller. Part of the charm, but it prevents using a keyboard for tracking purposes, which is something I demand in a multiple-filter resonator. In a single filter, it's no harm.

I do remember, when controlling the Buchla via computer/CV conversion, to have to add a "note/gate" just prior to the one with which I wanted to begin recording on. The first note didn't fully open the filter/VCA. I didn't measure if it was the output of the Buchla envelope or not, or if said envelope required different/higher gating.
This is not the place I'd imagined it to be.

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Post by snoop » Sat Feb 13, 2010 10:28 am

Thanks for all the information! I learn a lot around here. Thomas White was kind enough to solder a dual vactrol on the PCB + include 2 x singel vactrols in the package. That way i can check out the difference between the two myself. Exciting

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Post by doctorvague » Sat Feb 13, 2010 11:28 am

I'm not an EE by any stretch, but I'm guessing you would need to change a resistor or 2 when going from 2 vactrols to a double one or vice versa. Twice as many LED's to light up with 2 separate vactrols vs 1 double one. I could be wrong about that - just a guess. It may not make any difference at all.

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Post by Peake » Tue Feb 16, 2010 2:08 pm

I remember seeing layout artwork on White's 292 PCBs for single or dual Vactrols, but I haven't checked his notes on whether it requires any change in the surrounding component values. My offhand guess is that none would be needed, but I'm not always right. :lol:
This is not the place I'd imagined it to be.

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Post by Funky40 » Tue Feb 16, 2010 5:48 pm

i swapped from single to dual vactrols on a fonik LPG, no partchanges where needed.

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Post by bf » Wed Feb 17, 2010 8:19 am

Peake wrote:I remember seeing layout artwork on White's 292 PCBs for single or dual Vactrols, but I haven't checked his notes on whether it requires any change in the surrounding component values. My offhand guess is that none would be needed, but I'm not always right. :lol:
I have built the White LPGs both ways. There is no change in surrounding components necessary.

Image

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Post by emdot_ambient » Wed Feb 17, 2010 10:09 am

Yeah, no component changes needed...I haven't built mine yet (I've got 2 boards), but I'm planning on using 2 dual vactrols, one fast and one slow...then add a switch to flip between them.

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Post by Peake » Wed Feb 17, 2010 2:24 pm

Thanks for the info.

Now to test my Vactrol stock for the ringiest ones...

:hmm:
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