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Plan B Model 13 Dual Timbral Gate - Setup/uses
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Author Plan B Model 13 Dual Timbral Gate - Setup/uses
drewtoothpaste
I'm wondering what people use their Model 13 for... the filter doesn't do much and the VCAs don't totally close (they leak a little in Amp mode and a lot in Filter + Amp mode.) It also "rings" for so long that I can't really do anything percussive with it - if I want it to close in any reasonable amount of time I have to mult the CV ins to both sides and go through the two gates in series.

I've had it for a few months but have been unable to do anything interesting with it, and given the rave reviews I've read elsewhere I'm wondering if it's miscalibrated.
thermionicjunky
I think it's hard for a lot of people to shake their expectations of resonant filter behavior from a non-resonant filter. In this case it's just supposed to get a bit brighter or darker. I believe that there is a trimmer to shorten the ringing. Or, you could just get the Doepfer LPG. It uses fast vactrols and has resonance (right?).
Scaff
I am loving mine for its fast response and the ring tone. Try to recalibrate the LPG or try it with a faster envelope.
drewtoothpaste
I understand that a 6db/oct non-resonant filter will sound different than a 12/24db/oct resonant filter - but it sounds like crap even compared to my Model 12 vactrol filter set to 6db/oct w/no resonance. smile
chinard
it took me a while to get the idea of how to use LPG properly. I didnt really get it at first.
personally i wouldnt want to recalibrate mine to make for a faster response time, that is the sound they are supposed to make. Think of it more of a 'slowpass gate' or a 'slew filter'

The best applications i have used my LPG for is to make really natural sounding plucking sounds by setting the envelopes to the fastest possible attack/release time. 1-2ms is plenty.
With a traditional vca this would only be enough time to register a pop or a tick, with a LPG you can hear the vactrols ring off the tail end to give you a brief harmonic ring that makes for a great plucking sound.

I also use my LPG as an outright replacement for traditional VCA.
VCA mode has nearly the speed you would associate with a traditional vca but with a little added warmth due to the vactrols. In this mode the offset does not perform any filtering. VCA mode also seems to have the least amount of leaking or bleed at envelope closed position.
In both mode it is wonderful for bass sounds right after a traditional VCF. It really adds alot more bottom end warmth to bass this way. In 'both' mode it seems to close the sound off a little better than straight up filter mode.

I found this interesting interview with Alessandro Cortini where he is talking about various plan b modules including the model 13 LPG and talks a bit about the appeal of the slow response and ringing.
dkcg
It's slow enough to make a pulse/square wave into a great envelope, especially lower frequencies. I pretty much only use it in place of a VCA for audio. The pulses straight out of the Triple timer sound great as do the pulses out of the programmable tap clock.

For more traditional VCA sounds and enveloping CVs, I go with the 132-3 (I think that's the model number, dual lin/log VCA).
wetterberg
hey Drew,
it's funny, because I've been thinking the same thing about the LPG; the tests I've heard have been leaky as hell compared to the Doepfer.

I guess I got caught up in everyone saying it's the dogs bollocks, but it didn't strike me as such.
Cybananna
chinard wrote:
i wouldnt want to recalibrate mine to make for a faster response time, that is the sound they are supposed to make. Think of it more of a 'slowpass gate' or a 'slew filter'

The best applications i have used my LPG for is to make really natural sounding plucking sounds by setting the envelopes to the fastest possible attack/release time. 1-2ms is plenty.
With a traditional vca this would only be enough time to register a pop or a tick, with a LPG you can hear the vactrols ring off the tail end to give you a brief harmonic ring that makes for a great plucking sound.

I also use my LPG as an outright replacement for traditional VCA.
VCA mode has nearly the speed you would associate with a traditional vca but with a little added warmth due to the vactrols. In this mode the offset does not perform any filtering. VCA mode also seems to have the least amount of leaking or bleed at envelope closed position.
In both mode it is wonderful for bass sounds right after a traditional VCF. It really adds alot more bottom end warmth to bass this way. In 'both' mode it seems to close the sound off a little better than straight up filter mode.


couldn't have said it better myself, so I won't. My thoughts exactly!
dkcg
chinard wrote:

In both mode it is wonderful for bass sounds right after a traditional VCF. It really adds alot more bottom end warmth to bass this way. In 'both' mode it seems to close the sound off a little better than straight up filter mode.


I use it in both mode 99% of the time. Try pushing a raw waveform through it, and then through a VCF. I send raw waves through it and into a M12 all the time, the M12 (which is also not self resonant) really gets the signal ringing even more. Just have to watch self-oscillation when using a resonant filter.
thermionicjunky
This description from the Makenoise Quad Multi-mode Gates page makes me very interested.

"In BOTH Mode the feedback is routed to provide DAMPING of the ringing vactrols. The effect of adding feedback in BOTH mode is not unlike placing your hand upon the head of a drum, while striking, thus allowing the user to control how much the Vactrols ring."
wetterberg
ah cool - negative feedback, nicely thought out!

I still have to wrap my head around the vactrol/LPF interaction that's going on, "ringing" being tied to what we'd perceive as resonance etc.
felix
I pretty much use mine as a replacement for a regular VCA as well.

If it rings too much, or doesn't sound right, I just use a regular VCA.

Maybe I have a good one, but mine does not bleed that bad. Unless I put some compressor or distortion after the modular (anything that will raise the noise floor) I can hear the bleed. Under normal circumstances though it's not that bad.

There are trimpots on the bottom of the main PCB of the M13, you might be able to adjust it so that it rings less (it shouldn't change any of the bleed when the gate is "fully closed" however).
drewtoothpaste
Maybe I'll record a bit of it and see what y'all think. I can't put my finger on what exactly it is that sounds wrong.

I've sent LFO-speed pulse/square-waves to it before as well as short envelopes and it doesn't "ring" so much as it bleeds. When I think of "ringing" I think of the way that resonant filters ring when you send pulses through them.
parasitk
With the Wiard Borg 2 I usually don't even bother with running an EG into it if I just want a tight pluck - a trigger pulse works great (check out my PluckYou clip for an example). No idea if the M13 responds in nearly the same way, but I figured I'd offer the idea.
felix
drewtoothpaste wrote:
Maybe I'll record a bit of it and see what y'all think. I can't put my finger on what exactly it is that sounds wrong.

I've sent LFO-speed pulse/square-waves to it before as well as short envelopes and it doesn't "ring" so much as it bleeds. When I think of "ringing" I think of the way that resonant filters ring when you send pulses through them.

This sounds exactly like the trim pots need adjusting. Basically, the gate is taking way too long to close. With shorter gate times, it's more of a "ring" sound than a serious leaking.

The trim pot adjustment couldn't be easier. Run some signal through one gate, with an EG patched to the CV in, and have the Offset turned all the way down. Turn the trimpot until you like it. One direction (CCW, I think) is "faster" and the other way is "slower". Repeat with the other LPG and trim pot.

The trimpots are on the back of the main PCB (the "solder side"). They're pretty much the only component back there, you can't miss them.

Just refrain from touching the actual solder joints on the back of the PCB, it's possible you could short something out...or give yourself more than a healthy shock.
drewtoothpaste
Thanks Felix, I'll check out the trimpots.

I patched up a simple patch to illustrate what I was talking about (A-155 CV thru A-156 quantizer to MFB OSC to LPG, trigger out of A-155 to VC on LPG) and I found when I multed the triggers I send to the LPG to the quantizer trigger in, it makes the bleed a little more tolerable.

What was happening before was that the audio going thru the LPG was changing pitch before the amp/filter would close again, so it sounded more bleed-y than if the pitch were held until the next trigger.

I'm still going to adjust it since I can't get the quick decay I hear in all the demos - not that I necessarily want to make "pock pock pock" FM sound but I would get more use out of a shorter ring/release time.
felix
drewtoothpaste wrote:
What was happening before was that the audio going thru the LPG was changing pitch before the amp/filter would close again, so it sounded more bleed-y than if the pitch were held until the next trigger.

Ah yes, I know exactly what you mean.

drewtoothpaste wrote:
I'm still going to adjust it since I can't get the quick decay I hear in all the demos - not that I necessarily want to make "pock pock pock" FM sound but I would get more use out of a shorter ring/release time.

Yeah, on mine, the top half can be very short (too short for my taste) and the lower half rings nicely. That being said, on a lot of the demos they're using extremely fast envelopes, ones that would make a typical VCA "click". It's not uncommon to even use trigger pulses to hit the LPG gates. Since the vactrols are so slow, the sound is indistinguishable from a very short envelope on the LPG.
drewtoothpaste
Anything longer than a trigger signal on mine makes it close intolerably slow, and I'd estimate it takes a full second for it to close even with triggers going to the VC inputs. The bottom one on mine also has a longer release as well...

I've thought before that I could mix in a negative, constant CV (maybe -0.2V?) with the trigger/EG CV to force it to close faster, but that's a lot of cables and effort for something that should work right to begin with. smile
felix
drewtoothpaste wrote:
I've thought before that I could mix in a negative, constant CV (maybe -0.2V?) with the trigger/EG CV to force it to close faster, but that's a lot of cables and effort for something that should work right to begin with. smile

Actually, I don't think that will make it close any faster, it just won't make it open very wide. It will "close faster" only because it didn't open as far.

The reason that is doesn't close faster is because the response of the photo-resistor is such that it slowly returns back to its highest resistance once light is no longer applied to it. There is a static amount of time that it takes to "fully close".

So let's say that this amount of time is 500ms. If you hit it with a 3ms trigger, it's going to take 500ms to close (total open time of 503ms), if you hit it with a 200ms trigger, it's still going to take 500ms to close (total open time of 700ms).

It doesn't matter how short the EG (or trigger) is, there will always been some set minimum amount of time it takes to full close, and that's part of what makes the characteristic "ring" of a vactrol based LPG. The trip pots on the M13 are used to adjust this though, within some tolerance.
Jari Jokinen
felix wrote:
Actually, I don't think that will make it close any faster, it just won't make it open very wide...

Indeed. You are not trimming the vactrols but the CV sensitivity.
Plan B
Guys,

your answer: VACTROLS.

Look at the specs. The lowest resistance possible in the VTL5C3/2 is 100 ohms. This is why there is 1/8 mv leakage, which was about 3 mv before I added the circuitry to cut it down.

Have I been hiding this fact? Hardly. Take a look at the copy on the Model 13 page on the EAR site. This copy has gone unchanged since originally posted back in 2005.

The issue is this is an adaptation of a Buchla circuit, whichruns at line voltage levels. At this amplitude, the leakage is there, but almost impossible to hear. In comes Deopfer with an amplitude level almost four tmes louder than line, and things start to change.

The Model 12 does not use the 3/2 vactrols and therefore, it doesn't ring nor leak. A Buchla 292 (and a Plan B Model 13) does. The both ring, and they both leak.
Jari Jokinen
Model 13 leakage almost impossible to hear? I would rather say, that sometimes the leakage doesn't matter.

My unit doesn't meet the specs at all.
D/A A/D
I'll hopefully have my QMMG within a week or two, expect many clips.
REwire
I don't understand this leakage issue. If you plug audio in to the Plan-B LPG and then the output to your amp and then keep the offset pot all the way counter clockwise and have nothing plugged in to the CV input, does audio leak through? That I haven't encountered on my two units. That's all I would call actual leakage.
dkcg
REwire wrote:
I don't understand this leakage issue. If you plug audio in to the Plan-B LPG and then the output to your amp and then keep the offset pot all the way counter clockwise and have nothing plugged in to the CV input, does audio leak through? That I haven't encountered on my two units. That's all I would call actual leakage.


I usually don't notice any significant leakage of any sort, but if you send a strong enough signal, it can get through. In one of my first PlanB videos on youtube, the "how to make plucks w/ PlanB" video, I did not realize that one of the gates had no CV coming into it to open and close it, so I kept cranking up the signal with filters, resonance, etc and it did seep through quite noticeably, but once I realized I had no gate CV, and plugged an M10 into it, it was WAY loud. But to me the leakage is minimal and I think more of a problem on higher frequencies (which ring less anyways), and if I really need ultra-silence b/t gate openings, I send that through the doepfer VCA with either the same envelope, or with a second slightly longer envelope.
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