Resonant Lopass Gate PCB's (New Batch 4/29/12)

[delayed]

a pcb layout would be very nice

[303monkey]

I'll have to reduce my order to 4 if this goes ahead

[djthomaswhite]

Hi all,

It is too early to reveal any specifics, however, one thing can be said at this time. I spoke with Don on the phone today and he approved a second non-commercial run of PCBs for this project. I already have a PCB with larger pad size since this was one of the items of feedback from the first run. The question is now how to support, plan, take orders, etc.

DO NOT PLACE ORDERS HERE!

I will likely finally update my naturalrhythmmusic.com page with information on the project so it has a more permanent home without any surfing through 21 plus pages of posts. Again, more to follow. I may sell vactrols, I may sell parts kits, I just don't know at this point.

There is one thing for sure... please take into consideration just how decent a man Don Buchla is for approving the second run. He was appreciative for the respect this community has offered to him and was thankful for me asking his permission in the first place. I may be taking liberty in saying so, but he seemed pleased people were interested in the older circuits. Either way, he is an example for all of us to follow in our diy efforts when it comes to sharing information about fun circuits and keeping the small industry alive.

I will post more information here about what the final plans will be. This will be a limited run, the final run, and I will do my best to make sure to fill orders up to the ability of my agreement with Don. Many thanks to all for inspiring a new run of this project. Back at you as soon as I can,

Thomas

[LektroiD]

I might be in for a couple more, especially if the design has any new modifications.

[DGTom]

This is great!

Big thanks from this DIY n00b Mr. White!

I've read thru the thread & it is truly inspirational, I'm really happy I'll get a chance to get some PCBs.

Thanks.

[fluxmonkey]

[numbertalk]

This is very exciting news. Thanks so much Thomas. Looking forward to picking up another couple boards from this final run.

[xpander]

i did end up seeing don yesterday, he definitely does not mind this sort of thing at all.

it'll be interesting to see how this compares to the 292e, great module.

[lexvortex]

Great!!! Looking forward to this, I will definitely get 4 boards, I just finished a 281 quad function generator and love it!

Thanks for doing another run,
Dave

[numbertalk]

Hi Thomas,

Just finished my first LPG module and everything is great, except the deep switch - when switched to "deep" the audio shuts off - it won't even self oscillate. The switch is working, continuity all checks out & I'm getting 47K resistance between pins 6 & 7 of the TL084 when in deep mode, but no sound. Any ideas?

Also, I want to make sure the frequency range I'm getting seems right. I have the trimmer set fully to one side, such that the low frequencies are shifted as much towards the ccw end of the frequency pot, if that makes any sense (in other words, before setting, I had the frequency pot at 4 and was getting no audio, but once I turned the trimmer totally this way I was getting the low end of the audio).

Anyway, it seems to be topping out at just under 33KHz with the frequency control set at 10 and then bottoming out at around 48Hz, but here with the frequency pot just at 4. In other words, I'm getting nothing when the frequency pot is set below 4. Sound right?

Any help greatly appreciated.

Thanks!!

[Tasmanian Alkaloid]

[numbertalk]

Thanks for the help. I went back and watched Thomas's youtube videos and mine is definitely doing something different. It doesn't work the way his does at all. Also tried hitting it with a fast pulse, changing the pulse width, the frequency setting on the LPG and readjusted the trimmer. I actually found when I have frequency at 10 I get very very *faint* sounds with modulation, but that's it in deep mode.

Thomas (or anyone), what might be causing this? Any ideas or suggestions? It seems like my frequency range or where it's placed along the spectrum of the frequency pot is very different from what I see in your videos. With frequency at 0 and heavy modulation my signal isn't as strong/the frequency is much lower than in your video, almost as though I'm already in deep mode.

[djthomaswhite]

As for the deep switch, it is simply a resistor connecting pins 6 and 7 of the TL084 if I remember right. You can try a different resistor, but essentially the deep switch allows you to simulate turning the frequency pot a whole extra turn "down" towards the deep direction. Here's why i added it...

With my LPGs, I was sending gate and pulses into them during the testing phase. In this I discovered, or should I say I was reminded, that each pulse and gate signal varied in voltage strength and duration and both of these factors lend to the opening and closing "distance" of the gate. So you can have a VERY short, but high voltage pulse that will open the gate a different distance than one of a lower voltage. Basic CV stuff right? No mystery there. But, with LPGs and this one in particular you have different modes of VCA/LPG or Both.

The tried and true bug sound of LPG's is using them as a VCA so that you don't hear any sound until it is triggered and when it is triggered the lovely vactrol lags the shape a bit. I added the deep switch to allow the freq/offset to be set so low you have more adjustment on the opening and closing "distance" due to the CV input. This might sound silly, but most LPGs do not have a CV input attenuator and this extended range allows for more custom sound without adding a CV input attenuator. Okay, back to the issue though...

Look for a short with the small PCB pads on your board. For the 50K resistor, try a 20K one. I use 49.9K in my boards actually. I hope this helps! You could wire up a 100K pot and find a setting that makes sense, remove it, measure the resistance and put a resistor in that is that value. Good luck! You'll like the results once you get it going.

Oh yeah, not sure if this affects anything, but are you using bipolar 15v?

Thomas

[numbertalk]

[djthomaswhite]

Check out:

http://www.naturalrhythmmusic.com/lopass.html

I have made a page dedicated to the 2nd run of boards and it has pictures, document packet, and other information all in one place. There is a PayPal cart to buy boards.

Current ETA on arrival of next batch/ship date is mid-June. Buy now so I know how many you need in advance of placing the order next week. Thanks!

Thomas

[lexvortex]

Great!! Just ordered four

Thanks for offering this project up again, and thanks to Don for letting this happen!
Dave

[xpander]

another 4 purchased!

[numbertalk]

Just paid for 2 boards!

[3vcos]

So are there any mods for this Lowpass gate to get different responses like highpass or bandpass?

[wicked1]

I just want to re-ask the question someone did a few pages back..
what is the benefit of running 2 in series?
Wouldn't it just give a steeper cut-off slope? (like chaining filter stages when designing a VCF)
Basically.. I ordered 2 pcb's. I'm building a little pre-patched synth (still fully patchable for modular use) and am thinking about using this as the VCA. Would I get the best use of my 2 pcb's by chaining the 2 together, and using the same vactrols in both, or would u suggest making one w/ the 3(faster) and one w/ the slower 4 vactrol? (I like the idea of building one of each, but just about every website about the lowpass gates says "you'll want to chain a couple together", and Im not sure why)

[jooks]

Just paid 2 boards. Many thanks!
/Erik

[krisp14u]

Hi just ordered a few more boards
is the finish on the new run of boards going to be the same as the last run ?

[parasitk]

Just ordered 3 more!

[djthomaswhite]

Hi all,

New run is the same as the last but with slightly larger soldering pads. Same lead-free finish that looks milky but solders fine. It's a coating to protect the "solderability" of the pads when it comes time to actually build it. I'll have them in plastic bags again to keep them fresh. Gotta keep it green if I can.

Thomas

[adambee7]

HI man
I don't get paid until end of month (MAY) but if there is any left i'll have four please.

adam