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

djthomaswhite · Joined: Nov 22, 2007 Posts: 140 Location: Orange, CA

"can I use the CV mixer and have a separate direct CV In by connecting points 1 and 2 to point 3 on the CV Jumpers?

If you want to have multiple CV jacks or inputs you have to "mix them" in the mixer section as it has a 100K input node to bring all signals together.

Thomas

recompas · Posted: Wed Oct 07, 2009 1:25 pm Post subject: odd offset cv behavior

So I put my first lpg clone board together a few months ago, but only recently have I really started doing a lot more with it, since I put it into my main modular rig. I've noticed a few things that are kind of weird. First, my resonance level is really weak....you can tell it will resonate, but not with the same effect as on the video, and doesn't self-oscillate.

the second problem i'm having, is that when i control the offeset with a + - 5v sine wave, it often makes a little pop and then no audio comes out for a few seconds, until i move the offset control, or it just comes back on its own. Its possible there's a grounding problem on the module, since evertying has been changed over to some banana jacks, and the LFO module is getting power off of a different rail, but i'm just not sure. curious if anyone else has experienced any weirdness.

Thanks!
-Travis

djthomaswhite · Joined: Nov 22, 2007 Posts: 140 Location: Orange, CA

Sounds Like a short of some kind. Double check all of your solder joints ro make sure you have clean joints with no solder bridges. I would bet this is your issue!!!

Also, if you run your sine signal thru an attenuator you may have a bad pit. Pots can go bad if you overheat them when attaching wires. Long shot, but hey, trying to help.

recompas · Posted: Mon Oct 12, 2009 1:35 pm Post subject:

ahh, thanks. there actually was a bad solder joint on a pot that was doing the cv attenuation. Sounds back to normal now....although like I said, it never truly self-oscillated, i still get some nice resonance. Anyway, thanks...this is quickly becoming one of my favorite filters.

LektroiD · Posted: Tue Oct 20, 2009 12:11 am Post subject:

numbertalk · Posted: Tue Oct 20, 2009 6:27 am Post subject:

fonik · Posted: Tue Oct 20, 2009 10:50 am Post subject:

nerdware · Joined: Jul 11, 2009 Posts: 91 Location: UK

Very nice diagrams. Thanks, Matthias.

LektroiD · Posted: Tue Oct 20, 2009 9:27 pm Post subject:

Thanks Matthias, excellent diagrams as always.

LektroiD · Posted: Sun Oct 25, 2009 9:43 am Post subject:

Just finished building my first one (also my first completed module - yay). I have a problem with the resonance going crazy (self oscillation) past 2 O'Clock on the dial, it nearly sent my speaker cones across the room! Any ideas what might cause this?

Also, in the 2U design... Where does the "CTRL" wire up to on the PCB?

LektroiD · Posted: Tue Oct 27, 2009 2:31 am Post subject:

A couple of other findings (as well as the questions posed above);

1) Should I lose resonance control in 'both' mode? The resonance seems to be non existent in both mode. I would have assumed 'both' meant VCA + VCF (which would include resonance).

2) The deep switch cuts the sound completely (as has been reported many times on this thread), is there a recommended resistor value to get this working?

fonik · Posted: Tue Oct 27, 2009 10:09 am Post subject:

djthomaswhite · Joined: Nov 22, 2007 Posts: 140 Location: Orange, CA

Deep Switch = Turn it on, put Offset all the way up and hit the module with CV's. The CV's will bring the sound through from the depths into existence. Should be if it was built right. I use it with amplified, and as short as possible of triggers.

Boards are in and will ship as scheduled next week!!!

Thomas

Brogram · Joined: Nov 18, 2008 Posts: 37 Location: NYC

I'm currently mounting 3 LPGs in one panel and have a silly question....
Rolling Eyes

If I wanted an extra output that combines the 3 LPG outs could I simply run the signal from each of the three boards and connect them at one output jack? Or could this present any issues?

Thanks,
Eric

numbertalk · Posted: Wed Nov 04, 2009 7:14 pm Post subject:

You would need to run these into a mixer circuit, something like this:

http://www.cgs.synth.net/modules/cgs04_mix.html

djthomaswhite · Joined: Nov 22, 2007 Posts: 140 Location: Orange, CA

Or better yet, you could use one of the mixer sections on one of the PCB's to mix the three outputs. This would mean one module has no CV or Audio mixer on the inputs, but it might be worth the sacrifice. Mixer sections on the pcb are jumpered in and out of the circuit. Otherwise they are two independent 3 input mixers.

Thomas

Tasmanian Alkaloid · Joined: Jun 29, 2008 Posts: 116 Location: Isle De Mort

fonik · Posted: Thu Nov 05, 2009 2:02 am Post subject:

djthomaswhite · Joined: Nov 22, 2007 Posts: 140 Location: Orange, CA

Last of the 3rd batch are for sale on www.naturalrhythmmusic.com/lopass.html

Would hate for anyone to miss out. I have between 30 and 40 left at this point. $15 each shipped to your door. Thanks!

Thomas

a100user · Joined: Oct 28, 2003 Posts: 158 Location: UK

Hi Thomas,

My boards arrived today.

Many thanks for a great service.

David

nerdware · Joined: Jul 11, 2009 Posts: 91 Location: UK

I got mine, too. Excellent service, thanks.

diablojoy · Posted: Sat Nov 14, 2009 12:17 am Post subject:

hi thomas
are there any plans to be doing any more board runs for these in the future ? as it seems to hint from the post heading this may be the final run
I already know that i will be wanting quite a few more of these Smile

djthomaswhite · Joined: Nov 22, 2007 Posts: 140 Location: Orange, CA

Thanks for the inquiry. Due to personal stuff and family plans changing (kid coming) I'll be moving to other newer board designs. After three batches I think everyone who needs one has one (or four). The last 40 are essentially sitting and orders have slowed dramatically now. However, strange things happen and they could go in a weekend due to people buying from two to six on average.

I don't plan to make more at this point. But frankly I didn't plan to make this batch until demand rose to a level that made it worthwhile. One forgets just how much time it takes to package, address, make customs form, and ship PCB's from the post office (long line this time of year). Just don't know if I can continue to commit to shipping in a window of time that is acceptable to me.

joshco · Joined: Nov 14, 2008 Posts: 55 Location: germany

Boards arrived, thank you very much for this project Very Happy

Dave Kendall · Posted: Sat Nov 14, 2009 12:24 pm Post subject:

Hey Thomas, Thanks for doing a final run. I had missed the last runs due to being broke, and am really glad I got another chance. Smile

I'll maybe try them with some home-rolled vactrols...... could be interesting......

cheers,
Dave