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 
Live streaming at radio.electro-music.com

  host / artist show at your time

poster

Please visit the chat
 Forum index » DIY Hardware and Software » MusicFromOuterSpace.com designs by Ray Wilson
External gate problem
Post new topic   Reply to topic Moderators: dnny, Uncle Krunkus, v-un-v
Page 1 of 1 [3 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
prgdeltablues



Joined: Sep 25, 2006
Posts: 222
Location: UK
Audio files: 12

PostPosted: Mon Sep 25, 2006 5:03 am    Post subject: External gate problem Reply with quote  Mark this post and the followings unread

Hi, new to the forum, just built my Soundlab over the summer. Working fine, needs a few knobs and I'll then get round to posting a picture. Brilliant machine. A couple of problems though.

I'm prototyping a ribbon controller for it, based on the stripboard resistor ladder which I saw described on this forum, and then using the second part of the circuit from the guitar trigger to provide a gate out. So the circuit basically goes : raw cv voltage -> op amp buffer -> cv out at this point -> diode, etc into op-amp comparator (without hysteresis) for gate out. Hope that makes sense.

Breadboarded using 741s, and the cv works fine. With the AR mode switch set to Trigger, it also all works fine - Frequency controlled by the external cv, Attack and Decay times controlled by those two pots on the soundlab. But with the mode set to Gate, I still get an Attack time, but no Decay time - just abrupt end when I release the switch and the raw cv voltage goes to 0. Guess I'll have to open the case up and check the wiring, but if anyone has any thoughts that would be great.

A second problem. Swapped the 741 over for a TL072 for both op-amp positions), and now instead of a clean end to the output, when I disconnect the raw cv voltage, the frequency decays irregularly down over about 1/2 second, then there's another 1/2 before a small click, and only then can a new note be started. It's actually a rather interesting effect, bit chorusy, but not one I was looking for. Has anyone else encountered this, with different op-amps - and does anyone have an explanation!

Thanks to Ray for a wonderful synth project and helpful website.

Peter
Back to top
View user's profile Send private message
prgdeltablues



Joined: Sep 25, 2006
Posts: 222
Location: UK
Audio files: 12

PostPosted: Mon Oct 02, 2006 9:36 am    Post subject: External gate problem Reply with quote  Mark this post and the followings unread

A follow-up. Worked out over the weekend that the reason there's no release time is that my external AR voltage is driven by the CV voltage. CV goes to 0 means AR drops to 0 too. Duh! Set up an independent gate voltage and it works fine. But the circuit still isn't happy with a TL072. Works OK with 741's. Going to get a bunch of other op-amps and try them out.

Peter
Back to top
View user's profile Send private message
Wild Zebra



Joined: Apr 28, 2005
Posts: 806
Location: Ohio
Audio files: 5

PostPosted: Mon Oct 02, 2006 12:05 pm    Post subject: Reply with quote  Mark this post and the followings unread

Cool glad you got it going. Looking forward to some pics.
_________________
"your stripes are killer bro"
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: dnny, Uncle Krunkus, v-un-v
Page 1 of 1 [3 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
 Forum index » DIY Hardware and Software » MusicFromOuterSpace.com designs by Ray Wilson
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