Vactrol based VC-PANNER

funkyfarm · Posted: Sat Dec 01, 2007 4:02 am Post subject:

(as requested)

Funky40 · Posted: Mon Dec 03, 2007 3:42 pm Post subject:

Salue Funkyfarm

i have soldered the PAN part on a prototypingboard now,
but the CV part i do not understand .

what is unclear is the CV input section. ( and i cannot read all your writing )

ok, one input is just the pot between V+ and V-
I prefer it between -15V and +15V so i think i must add resistors. does somebody know which values ? 47K to V- AND V+ ?
CVin 1 is that with the 30k R (!!! Wink

) , thats clear

but what i need more is not clear.
I just like to have the simple PAN modul for first testing.
the offset pot and 2x a normal CV input should be fine, or not ?

i think i just can make it with 2x a normal CV input as shown for CV1, isn't it so ?

behind the 10K centre Trim are 2 resistors.
1 Value i cannot read.
They are just going to ground, no connection to the opamp ?

edit:
oh, and which transistors do i need. BC547, is that good ?

funkyfarm

Funky40 · Posted: Tue Dec 04, 2007 11:42 am Post subject:

Thank you Funkyfarm.
It seems to be clear now. ( just had a look )
The descriptions given by you are very good

funkyfarm · Posted: Mon Feb 11, 2008 3:45 am Post subject:

I've noticed my module has a little extra gain (Us vs Ue).

You could maybe swap 110k resistors for 100k Embarassed

This is a great module.

I plan a dual cross fader for spring 2008.

fonik · Posted: Mon Feb 11, 2008 3:53 am Post subject:

funkyfarm · Posted: Mon Feb 11, 2008 3:59 am Post subject:

...no...and that's boring me...

funkyfarm · Posted: Sun Mar 30, 2008 11:53 pm Post subject:

funkyfarm · Posted: Tue Apr 15, 2008 3:26 am Post subject:

It's alive !

In these 5.1 days, and fifty years late, I've decided to turn on stereophony !

This module even gave my modular system a new name : the brand new STEREO HERO system.

Cool

funkyfarm · Posted: Sun Sep 14, 2008 5:37 pm Post subject:

I've found a small problem : I can remember having trim the modules in order to have "a well-balanced stereo image" (LEFT=RIGHT) when intial potentiometer is at twelve o'clock.
But this seems to shift control symetry ; when I plug a perfect +/-5V lfo into CV input, my green LED dims more than my RED one...

I'll check trimming once more.

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

Just wondering if anyone has attempted a layout for this Vactrol X-fade circuit? Would be great for VC cross fading waveforms, dry/wet signals, etc.

thermionicjunky · Joined: Dec 07, 2006 Posts: 90 Location: san francisco

I would like to see PCBs for these x-fade and panning circuits. I would buy a few of each.

mono-poly · Posted: Fri Jun 05, 2009 4:07 am Post subject:

Yes pcbs would be very welcome!

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

I guess this circuit is simple enough that one could hand-draw a layout for press'n'peel. I suppose I should give it a shot... assuming no one else has already.

mono-poly · Posted: Fri Jun 05, 2009 5:36 pm Post subject:

What's good free pcb design software?
Maybe i will give it a first try.

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

This was posted today by Tim Servo in the 'layout factory' sub-forum (along with tips, etc.):

"I can highly recommend KiCAD as a PCB layout program. It can generate printouts if you etch your own boards, or Gerber files if you have them professionally done. It has a reasonable library of parts, and doesn't have any size restrictions (might be limited to four layers, but if you need more than that, you're probably laying out PCBs for a living using a high-end CAD tool). The best part? It's FREE!
http://kicad.sourceforge.net/wiki/forums.html/Main_Page "

widdly · Posted: Fri Jun 05, 2009 10:17 pm Post subject:

I built this on perfboard and used an on-off-on switch to toggle between pan-balance-crossfade modes. It's like the switch on the Universal Audio Processor of a Serge (at least I imagine it is, never having touched a real serge)

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Posted Image, might have been reduced in size. Click Image to view fullscreen.

I used hand made vactrols and it works nicely although it is hard to get it properly balanced. Matching the LED brightness does not the vactrols.

Funky40 · Posted: Sat Jun 06, 2009 1:52 am Post subject:

funkyfarm · Posted: Wed Jun 10, 2009 9:54 am Post subject:

Funky40 · Posted: Wed Jun 10, 2009 10:32 am Post subject:

widdly · Posted: Wed Jun 10, 2009 7:58 pm Post subject:

I used Scotts circuitry, but with homemade vactrols. The problem I got was that the same amount of current from the CV circuit would produce different resistances from the LDR's. However I could compensate for this using the trimmer....but then the front panel LED's would not be equal brightness when the pan was in the centre.

I could better match the LDR's or not mount the LED's on the frontpanel. Instead I just ignored since the sound is fine and the LED's look cool anway.

9u4f47ut · Joined: Jul 03, 2009 Posts: 1 Location: Brooklyn

seem to be having a bit of trouble with my homemade vactrols burning out in the Verbos crosspanning circuit ...any suggestions?

inform3r · Joined: Sep 03, 2006 Posts: 59 Location: nyc

Anyone come up with a solid layout yet? I know it can be built on perf but a press 'n peel layout would be great. Like Eric said, this can be implemented in so many ways. That's why a dedicated PCB would be so nice.

I read through the whole thread and I can't exactly tell if anyone has successfully been able to get an even fade with this circuit yet. Seems like funky farm might have? What's the report?

funkyfarm · Posted: Thu Jul 30, 2009 12:34 am Post subject:

i don't know how to do pcb layout...
i was vexed for a long time with this project.

->veroboard

inform3r · Joined: Sep 03, 2006 Posts: 59 Location: nyc

funky,
Why were you vexed? I don't exactly remember the details of the thread at the moment but for some reason I recall you eventually getting good results. Am I mistaken? Based on your post maybe it's not such an easy circuit? What exactly is the problem anyway? The schematic Scott Stites made looks really good. Mind you, I haven't tried it or gone over it with a fine-tooth comb. I would love to have a panner though. Especially one that uses vactrols. Plays right in to my vactrol/Buchla fetish.

-John