electro-music.com   Dedicated to experimental electro-acoustic
and electronic music
 
    Front Page  |  Articles  |  Radio
 |  Media  |  Forum  |  Wiki  |  Links  |  Store
Forum with support of Syndicator RSS
 FAQFAQ   CalendarCalendar   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   LinksLinks
 RegisterRegister   ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in  Chat RoomChat Room 
 Forum index » DIY Hardware and Software » Thomas Henry designs
Voltage Controlled Crossfader/VCA
Post new topic   Reply to topic Moderators: Scott Stites
Page 1 of 2 [28 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Goto page: 1, 2 Next
Author Message
Thomas_Henry



Joined: Jul 24, 2009
Posts: 164
Location: N. Mankato, MN
Audio files: 3

PostPosted: Mon Aug 06, 2012 7:57 pm    Post subject: Voltage Controlled Crossfader/VCA
Subject description: Another circuit for your consideration
Reply with quote  Mark this post and the followings unread

Hi Gang,

As promised, here is another circuit for you to play with. It can be used either as a voltage controlled crossfader or as an ordinary VCA. I hit upon this when finally realizing something that was in front of me all the time---the control currents though the voltage-to-current converter are symmetric yet opposite. It's an obvious idea once you see it and has probably been used before. But I was glad to stumble upon it.

Null out the DC thumps in the usual way. (Turn the audio inputs down, then apply a 0 to +5V square wave to the CV input.)

The usual legalese applies. Feel free to use this for personal applications but don't copy, or produce commercially. Anyone wanting to do a non-commercial PCB for EM users please contact me first.

Have fun!

Thomas Henry


Sheet 1.jpg
 Description:
Schematic --- Sheet 1
 Filesize:  53.57 KB
 Viewed:  876 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

Sheet 1.jpg



Sheet 2.jpg
 Description:
Schematic --- Sheet 2
 Filesize:  77.2 KB
 Viewed:  736 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

Sheet 2.jpg



Parts List.jpg
 Description:
Parts List
 Filesize:  51.65 KB
 Viewed:  493 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

Parts List.jpg


Back to top
View user's profile Send private message
v-un-v
Janitor
Janitor


Joined: May 16, 2005
Posts: 8933
Location: Birmingham, England, UK
Audio files: 11
G2 patch files: 1

PostPosted: Tue Aug 07, 2012 3:14 am    Post subject: Reply with quote  Mark this post and the followings unread

Looks fun Mr Henry! Cheers! Very Happy
_________________
ACHTUNG!
ALLES TURISTEN UND NONTEKNISCHEN LOOKENPEEPERS!
DAS KOMPUTERMASCHINE IST NICHT FÜR DER GEFINGERPOKEN UND MITTENGRABEN! ODERWISE IST EASY TO SCHNAPPEN DER SPRINGENWERK, BLOWENFUSEN UND POPPENCORKEN MIT SPITZENSPARKSEN.
IST NICHT FÜR GEWERKEN BEI DUMMKOPFEN. DER RUBBERNECKEN SIGHTSEEREN KEEPEN DAS COTTONPICKEN HÄNDER IN DAS POCKETS MUSS.
ZO RELAXEN UND WATSCHEN DER BLINKENLICHTEN.
Back to top
View user's profile Send private message Send e-mail
inlifeindeath



Joined: Apr 02, 2010
Posts: 316
Location: Albuquerque, NM

PostPosted: Wed Aug 08, 2012 10:17 am    Post subject: Reply with quote  Mark this post and the followings unread

can't wait to try out the new designs thomas! thanks as always for your work!
_________________
http://www.youtube.com/user/borisandfef
Back to top
View user's profile Send private message Visit poster's website
widdly



Joined: Jun 25, 2007
Posts: 266
Location: singapore
G2 patch files: 2

PostPosted: Wed Nov 07, 2012 8:39 am    Post subject:   Reply with quote  Mark this post and the followings unread

Thanks for another great design Thomas.

I built it this afternoon on perf board and it works very nicely. Like the other TH designs I've built, the input ranges on all the controls are tuned perfectly.

Very Happy
Back to top
View user's profile Send private message
fonik



Joined: Jun 07, 2006
Posts: 3855
Location: Germany
Audio files: 23

PostPosted: Tue Sep 22, 2015 5:17 am    Post subject: Re: Voltage Controlled Crossfader/VCA
Subject description: Another circuit for your consideration
Reply with quote  Mark this post and the followings unread

while looking around for a simple crossfader CV circuitry i found a very similiar on an old tom gamble EFM dual VCA, however, your solution is much more elegant and adds a nice touch with the overall volume control using the emitters!
thank you!

_________________
Posted Image, might have been reduced in size. Click Image to view fullscreen.
cheers,
matthias
____________
fonitronik at
FlickR (pix) / SoundCloud (sounds) / YouTube (vids) / Vimeo (vids) / facebook (news)
Back to top
View user's profile Send private message Send e-mail Visit poster's website
elmegil



Joined: Mar 20, 2012
Posts: 1939
Location: Chicago
Audio files: 16

PostPosted: Tue Sep 22, 2015 7:07 am    Post subject: Reply with quote  Mark this post and the followings unread

Excellent, thanks Thomas!

(Previous post deleted; still need the reminder not to post before finishing my tea)
Back to top
View user's profile Send private message
Sethkaine



Joined: Sep 26, 2015
Posts: 16
Location: Suisse

PostPosted: Mon Sep 28, 2015 2:48 am    Post subject:  expo converter Reply with quote  Mark this post and the followings unread

Hello Thomas,

I'm trying myself to your OTA designs : learning, breadboarding, etching, soldering, testing, listening. I love your designs from birthofsynth by the way. Wink

Sounds great to discover "new to my knowledge" designs in this forum. I'll going to try it out.

continue the good job and a big thank you for your schematics you're pleasing my ears.

_________________
my youtube channel - https://www.youtube.com/user/SethKaine/videos
my paper mix - https://paper.fiftythree.com/1865071
Back to top
View user's profile Send private message
wackelpeter



Joined: May 05, 2013
Posts: 327
Location: germany
Audio files: 9

PostPosted: Tue Feb 02, 2016 12:20 pm    Post subject: Reply with quote  Mark this post and the followings unread

Nice design Thomas, many thanks for that very cool circuit. Very Happy

It's not only a Crossfader or VCA also some kind of manual or voltage controlled wavefolder/mangler when you feed two waveforms from one VCO into it.

Like it thumleft

Makes me feel i need a second one... Smile

_________________
https://soundcloud.com/bastian-j
Back to top
View user's profile Send private message
richardc64



Joined: Jun 01, 2006
Posts: 663
Location: NYC
Audio files: 26

PostPosted: Tue Feb 02, 2016 3:13 pm    Post subject: Reply with quote  Mark this post and the followings unread

And still no love for mine.

http://www.sdiy.org/richardc64/mmvca/

_________________
"I am endeavoring, ma'am, to create a mnemonic memory circuit... using stone
knives and bearskins." -- Spock to Edith Keeler
Back to top
View user's profile Send private message Visit poster's website
LFLab



Joined: Dec 17, 2009
Posts: 420
Location: Rosmalen, Netherlands

PostPosted: Wed Feb 03, 2016 3:58 am    Post subject: Reply with quote  Mark this post and the followings unread

Which IS very interesting! Have you tried this with the LM13700 schematic already, Richard?
Back to top
View user's profile Send private message
roglok



Joined: Aug 28, 2010
Posts: 199
Location: uptown

PostPosted: Wed Feb 03, 2016 8:22 am    Post subject: Reply with quote  Mark this post and the followings unread

richardc64 wrote:
And still no love for mine.

http://www.sdiy.org/richardc64/mmvca/


thanks for the reminder, richard. i've meant to prototype your circuit but totally forgot about it...
Back to top
View user's profile Send private message
richardc64



Joined: Jun 01, 2006
Posts: 663
Location: NYC
Audio files: 26

PostPosted: Fri Feb 05, 2016 8:13 am    Post subject: Reply with quote  Mark this post and the followings unread

LFLab wrote:
Which IS very interesting! Have you tried this with the LM13700 schematic already, Richard?


Negative, LF. I have other priorities. But anyone is welcome come to experiment with the idea: Capacitor couple the audio inputs, give it a better current source, perhaps with Lin-Log response.

Etc.

_________________
"I am endeavoring, ma'am, to create a mnemonic memory circuit... using stone
knives and bearskins." -- Spock to Edith Keeler
Back to top
View user's profile Send private message Visit poster's website
wackelpeter



Joined: May 05, 2013
Posts: 327
Location: germany
Audio files: 9

PostPosted: Fri Feb 05, 2016 11:35 am    Post subject: Reply with quote  Mark this post and the followings unread

richardc64 wrote:
LFLab wrote:
Which IS very interesting! Have you tried this with the LM13700 schematic already, Richard?


Negative, LF. I have other priorities. But anyone is welcome come to experiment with the idea: Capacitor couple the audio inputs, give it a better current source, perhaps with Lin-Log response.

Etc.


Damn... that's what i forgot on my TH X-Fader because i couldn't wait to test it.... Smile didn't recognized the two blank holes on my frontpanel...

_________________
https://soundcloud.com/bastian-j
Back to top
View user's profile Send private message
sompost



Joined: Aug 17, 2010
Posts: 52
Location: Switzerland

PostPosted: Sat Feb 27, 2016 2:58 am    Post subject: Crossfader-only Reply with quote  Mark this post and the followings unread

Hi all,

I would like to use this great circuit as a voltage controlled mixer (crossfader option on sheet 1 above). Because the master level would always be set to maximum level, and envelope control would not be needed, the whole branch to the left of R11 (between Q1 and Q2) seems unnecessary for a crossfader-only use. Am I right?

What would I have to replace that branch with? Do I need the buffer (IC3c) or can I just supply +15V via some resistance to the point between Q1 and Q2? What would that resistance be?

Thanks!

_________________
Built: MFOS SLMS plus, SL Ultimate & Expander, 10 step seq; SLMS MkII; PAiA FatMan, Mutable-Instruments Shruthi-1
Building: Maddox MonoWave; Auduino; ASM-2; Minimoog Clone; Jasper Wasp Clone
Backlogging: MFOS 16 step seq; TH SN Voice; Takeda One Board Farm; Okita Vocoder; Page TR-9090; TH GM Voice, AY Voice
Back to top
View user's profile Send private message Visit poster's website
4b11b4



Joined: Sep 17, 2016
Posts: 1
Location: Oregon

PostPosted: Sat Sep 17, 2016 12:47 pm    Post subject: Re: Crossfader-only Reply with quote  Mark this post and the followings unread

sompost wrote:
Hi all,

I would like to use this great circuit as a voltage controlled mixer (crossfader option on sheet 1 above). Because the master level would always be set to maximum level, and envelope control would not be needed, the whole branch to the left of R11 (between Q1 and Q2) seems unnecessary for a crossfader-only use. Am I right?

What would I have to replace that branch with? Do I need the buffer (IC3c) or can I just supply +15V via some resistance to the point between Q1 and Q2? What would that resistance be?

Thanks!


Did you ever build this?
Back to top
View user's profile Send private message
LFLab



Joined: Dec 17, 2009
Posts: 420
Location: Rosmalen, Netherlands

PostPosted: Sun Sep 18, 2016 1:01 am    Post subject: Reply with quote  Mark this post and the followings unread

By the way, I have built RichardC64's version with LM13700, and it works fine.
Forgot to add capacitors to the audio inputs though, and I haven't calibrated it yet, but it does work. (let me know if you'd like a few boards Richard).
Back to top
View user's profile Send private message
sompost



Joined: Aug 17, 2010
Posts: 52
Location: Switzerland

PostPosted: Sun Sep 18, 2016 6:39 am    Post subject: Re: Crossfader-only Reply with quote  Mark this post and the followings unread

4b11b4 wrote:
Did you ever build this?


No, I didn't. First, I've got plenty of other unfinished business to do, and second I dropped the voltage controlled mixer from the design.

Ralph

_________________
Built: MFOS SLMS plus, SL Ultimate & Expander, 10 step seq; SLMS MkII; PAiA FatMan, Mutable-Instruments Shruthi-1
Building: Maddox MonoWave; Auduino; ASM-2; Minimoog Clone; Jasper Wasp Clone
Backlogging: MFOS 16 step seq; TH SN Voice; Takeda One Board Farm; Okita Vocoder; Page TR-9090; TH GM Voice, AY Voice
Back to top
View user's profile Send private message Visit poster's website
richardc64



Joined: Jun 01, 2006
Posts: 663
Location: NYC
Audio files: 26

PostPosted: Mon Sep 19, 2016 8:45 am    Post subject: Reply with quote  Mark this post and the followings unread

LFLab wrote:
By the way, I have built RichardC64's version with LM13700, and it works fine.
Forgot to add capacitors to the audio inputs though, and I haven't calibrated it yet, but it does work. (let me know if you'd like a few boards Richard).


That's great, LFLab. It's good to know that that past success wasn't a fluke. What values did you use for the Initial CV pot and the mystery resistor?

As for boards... Thanks for the offer, but I dunno. My prototype is still collecting dust, here. I'll let you know.

_________________
"I am endeavoring, ma'am, to create a mnemonic memory circuit... using stone
knives and bearskins." -- Spock to Edith Keeler
Back to top
View user's profile Send private message Visit poster's website
LFLab



Joined: Dec 17, 2009
Posts: 420
Location: Rosmalen, Netherlands

PostPosted: Tue Sep 20, 2016 3:21 am    Post subject: Reply with quote  Mark this post and the followings unread

Not sure what the mystery resistor is (maybe I should read everything before plonking something in Eagle Very Happy ), but this is what I have now, no wiring needed.
Posted Image, might have been reduced in size. Click Image to view fullscreen.

The lower section is one of Ray's (MFOS) VCA's.



(sorry for the OT discussion)
Back to top
View user's profile Send private message
richardc64



Joined: Jun 01, 2006
Posts: 663
Location: NYC
Audio files: 26

PostPosted: Tue Sep 20, 2016 6:21 pm    Post subject: Reply with quote  Mark this post and the followings unread

LFLab wrote:
Not sure what the mystery resistor is...

Oops. I neglected to include it in the 13700 schema. In the 3080 version it's at the -v end of the Initial CV pot. It's supposed to offset the range of that pot so that with no CV, when the pot is in the centered position a signal on Xin or Yin is at equal levels on both outputs.

I like that you included a normal VCA on your board. I may want one after all Very Happy

_________________
"I am endeavoring, ma'am, to create a mnemonic memory circuit... using stone
knives and bearskins." -- Spock to Edith Keeler
Back to top
View user's profile Send private message Visit poster's website
Cfish



Joined: Feb 24, 2016
Posts: 450
Location: Indiana

PostPosted: Wed Sep 21, 2016 6:22 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thank you Thomas.
so much of my modular is built from your schematics. I know I can perfboard them up and count on them to work.
That always means a lot to me. Will give this one a try.
Back to top
View user's profile Send private message
VinL



Joined: Jan 24, 2017
Posts: 1
Location: Québec

PostPosted: Tue Jan 24, 2017 12:06 pm    Post subject: Reply with quote  Mark this post and the followings unread

First post!

I've found a minor mistake in the crossfader/vca schematic. On the schematic pin 13 of the TL074 is labelled as the non-inverting input and pin 12 as the inverting input whereas it should be the opposite. I was actually building a dual version of vca-1, wich is very similar, with lm13700 and using both schematics got me stumbling on this anomaly.

BTW I love Thomas Henry designs!!! My favorites since I got into synth DIY about a year ago.
Back to top
View user's profile Send private message
Thomas_Henry



Joined: Jul 24, 2009
Posts: 164
Location: N. Mankato, MN
Audio files: 3

PostPosted: Tue Jan 24, 2017 8:54 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for pointing that out.

To be clear, everyone, the pinout in the schem is correct, so build away! Only the plus and minus signs in the op-amp representation of IC3d are reversed.

Thomas Henry
Back to top
View user's profile Send private message
ReToxx



Joined: Dec 06, 2016
Posts: 8
Location: Germany

PostPosted: Tue Feb 14, 2017 3:18 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hello everybody,
I want to build a small circuit wich allows me to feed back the normal output and the inverted one of a filter back to its input by a voltage controlled crossfader. So i want to have a knob which has no output in its middle position,
full ccw would be the inverted only (which also means no output at the output;-) ), full cw would be the normal output. And I also want cv control over the crossfading, where the knob acts as a starting point for the cv...
I want to leave as much as possible, but I don't know how to deal with that amp stuff thats going to in between the two transistors...
I already left the ac/dc switch, and the attenuators at the inputs, as well as the dc offset trimmers, as i will use it only for audio. And i added an attenuverter at the cv in...
don't know if that all makes sense and what to do with the input at the transistor, maybe i could only leave the initial gain pot as a trimmer, but to what value do i have to trimm that? or can i somehow set a voltage right at the transistors and get rid of the opamps there...
thanks so much for any advice


VC CROSSFADER.jpg
 Description:
 Filesize:  160.44 KB
 Viewed:  17 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

VC CROSSFADER.jpg


Back to top
View user's profile Send private message
fonik



Joined: Jun 07, 2006
Posts: 3855
Location: Germany
Audio files: 23

PostPosted: Tue Feb 14, 2017 10:55 pm    Post subject: Reply with quote  Mark this post and the followings unread

ReToxx wrote:
I want to leave as much as possible, but I don't know how to deal with that amp stuff thats going to in between the two transistors...

i used 20k there (from +12V).

_________________
Posted Image, might have been reduced in size. Click Image to view fullscreen.
cheers,
matthias
____________
fonitronik at
FlickR (pix) / SoundCloud (sounds) / YouTube (vids) / Vimeo (vids) / facebook (news)
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic Moderators: Scott Stites
Page 1 of 2 [28 Posts]
View unread posts
View new posts in the last week
Goto page: 1, 2 Next
Mark the topic unread :: View previous topic :: View next topic
 Forum index » DIY Hardware and Software » Thomas Henry designs
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
e-m mkii

Please support our site. If you click through and buy from
our affiliate partners, we earn a small commission.


Forum with support of Syndicator RSS
Powered by phpBB © 2001, 2005 phpBB Group
Copyright © 2003 through 2009 by electro-music.com - Conditions Of Use