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

Attorks · Joined: Jun 01, 2009 Posts: 6 Location: Netherlands

I have uploaded a small demo to YouTube:
http://www.youtube.com/watch?v=u9xbWdPPch4&fmt=18

valis · Posted: Thu Jun 18, 2009 11:14 am Post subject: Asterisk Question

Greetings Friends and Modular Enthusiasts,

I'm sorry if there's a better forum or thread to ask these questions or if they have been asked already but I couldn't find an answer..

I have a Rev 3.0 board and I don't understand why some resistor values have and asterisk (or two) next to the value on the PCB. For example, there's two asterisks next to a 1K resistor (right above the out and inv.) and there's one asterisk by the 47K in the top right corner.

I searched through the building docs but couldn't find out what this is supposed to indicate (although there seems to be asterisks in the BOM). Thanks for your time. Sorry if I'm being a bit dense..

Also, are the pre-order boards shipping soon? No hurry, I just want to make sure they weren't lost in the mail..

Thanks for your time. I really can't wait to build this filter..

-David

Attorks · Joined: Jun 01, 2009 Posts: 6 Location: Netherlands

valis · Posted: Thu Jun 18, 2009 2:10 pm Post subject:

I knew it was something obvious that I was missing and that turns out to be correct. Thanks for the reply!

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

Hi folks!

The boards have arrived this week. I am busy packing them up and will be shipping in two batches. 1, I will rush out the US orders since I can quickly get them together and pay for shipping via PayPal. 2, I will ship the International orders. My wife will help me fill out the troublesome little customs slips that we have to attach to the packages. I hope to have the lot of boards all shipped within 1 weeks time. Many thanks for the orders guys! The new boards look great and I will get them out as quick as possible. Cheers,

Thomas

adambee7 · Joined: Apr 04, 2009 Posts: 420 Location: united kingdom

nice one man. What vactrols would you suggest to use. Which one is quicker and which one is slower. Wouldn't mind doing two different types. Very Happy

isacsen · Posted: Mon Jun 22, 2009 1:16 am Post subject:

I've bought two different versions of the vactrols:

The single VTL5C4 from SmallBear Electronics at $6.00 a piece (you need 2 of these for one pcb). This is the slow version that I believe you can hear in Thomas' first video.

The dual vactrol VT5C3/2 from Bridechamber at $6.50 a piece (only one is needed for one pcb) for a faster response.

Hope this helps!

adambee7 · Joined: Apr 04, 2009 Posts: 420 Location: united kingdom

nice one. one of each it is then. Very Happy

reve · Joined: Feb 23, 2008 Posts: 149 Location: USA

davebr · Joined: Jun 09, 2007 Posts: 198 Location: portland, or

I see in the previous posts that the Inv Out was added so that a reversing attenuator for CV could be added. Could someone explain to me the wiring to implement this?

I understand reversing attenuators, but I can't figure out how to have both normal and reversing CV attenuators using just the Inv Out.

Thanks.

isacsen · Posted: Thu Jun 25, 2009 7:29 am Post subject:

I was thinking about adding a reversing attenuator myself.

I was also looking at the CGS 075 Slope and realised that in the lower left corner of the schematic, there is what appears to be a reversing attenutor:

http://www.cgs.synth.net/modules/pic/schem_cgs75_vcs.gif

So, I've tried to apply this to the LPG schematic. My additions are in red.

Can anyone confirm that this will work? Not sure about the 20-25k pot value, though. I understand that the mod will destroy any precision (amplification, tracking, etc) that was setup throughthe IN1 - IN3 inputs, but if you're not using these, then I don't see any problems? (Ducking)

Thanks!

IGJ MOD - Reversing Attenuator input - Final.JPG

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IGJ MOD - Reversing Attenuator input - Final.JPG

303monkey · Joined: Mar 11, 2008 Posts: 65 Location: NODNOL

Does anybody know if Allied Electronics ship internationally?
They have cheap vactrols available.

Luka · Joined: Jun 29, 2007 Posts: 1003 Location: Melb.

yup
i bought 30 a month or two back
shipping to australia was kind of high but not too bad

parasitk · Joined: Sep 21, 2008 Posts: 69 Location: NYC

I received my second round of boards today, thanks!

boosimas johnson · Joined: Nov 15, 2008 Posts: 13 Location: arizona

boards came as well, thankyou, they look great

panda30y · Joined: Apr 12, 2009 Posts: 17 Location: Detroit, Michigan

I got my 4 boards yesterday, thanks alot!

Also, nobody has answered my question I asked a few weeks ago yet. It may be because it's a trivial question, but I noticed that Thomas' bom from mouser has specified 4 vishay precision pots for the mixing sections. Are precision pots specified for a reason? Otherwise I will buy cheaper pots. Thanks.

LektroiD · Posted: Sat Jun 27, 2009 11:54 am Post subject:

sduck · Posted: Sat Jun 27, 2009 6:02 pm Post subject:

JohnLRice · Joined: Jul 29, 2008 Posts: 71 Location: Western WA USA

I got my 2 boards today, Thanks Thomas! Cool

panda30y · Joined: Apr 12, 2009 Posts: 17 Location: Detroit, Michigan

davebr · Joined: Jun 09, 2007 Posts: 198 Location: portland, or

isacsen · Posted: Mon Jun 29, 2009 5:03 am Post subject:

Thats very clever, Dave.

Have you thought about using the 4th unused U2 op-amp for a second reversing attenuator, or do you prefer having a normal attenuator as well (instead of two reversing)?

Thanks for sharing.

davebr · Joined: Jun 09, 2007 Posts: 198 Location: portland, or

ericcoleridge · Joined: Jan 16, 2007 Posts: 889 Location: NYC

I would like to find a way to switch 2 LEDs on and off to indicate the current mode ala the original buchla faceplate. Could there be a way to do so using the optional on-boards op-amps?