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 » Clavia Nord Modular » Nord Modular G2 Discussion
Skewing the output of an LFO
Post new topic   Reply to topic Moderators: Nord Modular Editors
Page 1 of 1 [12 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
AngusHastie



Joined: Aug 04, 2004
Posts: 136
Location: London, England
Audio files: 2
G2 patch files: 15

PostPosted: Wed Dec 14, 2005 8:18 am    Post subject: Skewing the output of an LFO Reply with quote  Mark this post and the followings unread

I'm using an LFO hooked up to the AM input of a volume env to fade a sound in and out, but I want to skew the LFO output so that it's off more than on. What's the best way of doing this? I've been messing around with mod amount modules etc. but they never seem to behave quite how I expect them to...
Cheers,
Angus
Back to top
View user's profile Send private message Visit poster's website
Blue Hell
Site Admin


Joined: Apr 03, 2004
Posts: 23491
Location: The Netherlands, Enschede
Audio files: 262
G2 patch files: 320

PostPosted: Wed Dec 14, 2005 11:49 am    Post subject: Reply with quote  Mark this post and the followings unread

Maybe I got it wrong, but sounds more like you'd want to alter the shape of the LFO. If so, using a shape LFO might be the way to go.
_________________
Jan
also .. could someone please turn down the thermostat a bit.
Posted Image, might have been reduced in size. Click Image to view fullscreen.
Back to top
View user's profile Send private message Visit poster's website
ian-s



Joined: Apr 01, 2004
Posts: 2664
Location: Auckland, New Zealand
Audio files: 42
G2 patch files: 626

PostPosted: Wed Dec 14, 2005 12:45 pm    Post subject: Reply with quote  Mark this post and the followings unread

Mix the lfo (bipolar) with a fixed level and pass through a diode module, the higher the bias, the more 'on' time.

Use a square wave (pos) lfo triggering a envelope through an inverter (gate on during off cycle), FM the lfo with a variable amount of its own output (pre-inverter). The rate is slowed during the on time.
Back to top
View user's profile Send private message
AngusHastie



Joined: Aug 04, 2004
Posts: 136
Location: London, England
Audio files: 2
G2 patch files: 15

PostPosted: Thu Dec 15, 2005 4:25 am    Post subject: Reply with quote  Mark this post and the followings unread

G2ian - What's a diode module? (Sorry - if it's not the name on the screen, I'm lost!!)
Is the attached what you mean in your second suggestion? I like that idea of self-modulating an LFO - very nifty.

Jan - I basically just want the LFO to AM an envelope to bring a sound in and out. But I wanted it to be off more than on. I thought I could just AM the envelope with a regular LFO that went through a level add module which was set to some negative value but that doesn't seem to work... Surely if you just subtract a fixed value from an LFO output, you end up with more negative values than positive values??


LFO trig.pch2
 Description:

Download
 Filename:  LFO trig.pch2
 Filesize:  946 Bytes
 Downloaded:  929 Time(s)

Back to top
View user's profile Send private message Visit poster's website
ian-s



Joined: Apr 01, 2004
Posts: 2664
Location: Auckland, New Zealand
Audio files: 42
G2 patch files: 626

PostPosted: Thu Dec 15, 2005 11:20 am    Post subject: Reply with quote  Mark this post and the followings unread

AngusHastie wrote:
G2ian - What's a diode module?


Sorry, my bad.

Its called a rect (short for rectifier) in the shaper group, it has a diode symbol on it.

The rect module can chop off the negative going part of the lfo wave so your idea with the leveladd will work. Applying neg control signals to the mult (vca) still lets signal through, its just an inverted signal.
Back to top
View user's profile Send private message
AngusHastie



Joined: Aug 04, 2004
Posts: 136
Location: London, England
Audio files: 2
G2 patch files: 15

PostPosted: Sat Dec 17, 2005 4:24 am    Post subject: Reply with quote  Mark this post and the followings unread

g2ian wrote:
Applying neg control signals to the mult (vca) still lets signal through, its just an inverted signal.


How does that work then? I thought a bipolar LFO signal oscillated between +64 and -63 and that if you sent this signal through a level add module set to a negative value, it would just subtract this value from the range...? Obviously I'm wrong but I'd lke to know why!
Back to top
View user's profile Send private message Visit poster's website
Blue Hell
Site Admin


Joined: Apr 03, 2004
Posts: 23491
Location: The Netherlands, Enschede
Audio files: 262
G2 patch files: 320

PostPosted: Sat Dec 17, 2005 6:40 am    Post subject: Reply with quote  Mark this post and the followings unread

AngusHastie wrote:

How does that work then?


You seem to mix up multiplication and addition.

The VCA, or multiplier, multiplies it's input signals. When you multiply a positive siganl with a negative one you'll get a negative output signal. But remember 64 times 64 equals 64 on the NM synths.

The adition thing that you desecribed is performed by mixer modules.

The LFO output goes down to -64 BTW, not -63.

_________________
Jan
also .. could someone please turn down the thermostat a bit.
Posted Image, might have been reduced in size. Click Image to view fullscreen.
Back to top
View user's profile Send private message Visit poster's website
AngusHastie



Joined: Aug 04, 2004
Posts: 136
Location: London, England
Audio files: 2
G2 patch files: 15

PostPosted: Sun Dec 18, 2005 6:38 am    Post subject: Reply with quote  Mark this post and the followings unread

So what does the LevAdd module do then? I thought it just added or subtracted a fixed amount to a signal, same as taking a mixer and sending the LFO to one input and a constant value to another input... Confused
Back to top
View user's profile Send private message Visit poster's website
ian-s



Joined: Apr 01, 2004
Posts: 2664
Location: Auckland, New Zealand
Audio files: 42
G2 patch files: 626

PostPosted: Sun Dec 18, 2005 10:48 am    Post subject: Reply with quote  Mark this post and the followings unread

AngusHastie wrote:
So what does the LevAdd module do then? I thought it just added or subtracted a fixed amount to a signal, same as taking a mixer and sending the LFO to one input and a constant value to another input... Confused


Thats exactly right.
If you look at the attached patch, the noise is audible during the positive going portion of the LFO wave. Adding a positive constant value to the LFO skews the on/off ratio. Disable the rect module and you can hear that the negative part of the LFO wave also lets sound through the multiplier.


levadd.pch2
 Description:
demo

Download
 Filename:  levadd.pch2
 Filesize:  1.13 KB
 Downloaded:  1269 Time(s)

Back to top
View user's profile Send private message
Blue Hell
Site Admin


Joined: Apr 03, 2004
Posts: 23491
Location: The Netherlands, Enschede
Audio files: 262
G2 patch files: 320

PostPosted: Sun Dec 18, 2005 3:11 pm    Post subject: Reply with quote  Mark this post and the followings unread

I'm sorry for the confusion, I didn't read well.
_________________
Jan
also .. could someone please turn down the thermostat a bit.
Posted Image, might have been reduced in size. Click Image to view fullscreen.
Back to top
View user's profile Send private message Visit poster's website
dasz



Joined: Oct 16, 2004
Posts: 1643
Location: vancouver, canada
Audio files: 29
G2 patch files: 56

PostPosted: Sun Dec 18, 2005 3:12 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hey AngusHastie,

I use a control sequencer to create my own shapers .. I feed the input (once passed through a levelconvert module) of the source into a perfectly diagonal control sequencer (step 0 = 0, step 126 = 127). The control input is the soud source. I use a smoother after the sequencer (usually a bit of glide or LPF), now I had really alter the behavior of my shaper.

/Dasz

_________________
http://www.dasz.com
Electronic Music Instruments From Vancouver, Canada
Back to top
View user's profile Send private message Visit poster's website
AngusHastie



Joined: Aug 04, 2004
Posts: 136
Location: London, England
Audio files: 2
G2 patch files: 15

PostPosted: Mon Dec 19, 2005 3:17 am    Post subject: Reply with quote  Mark this post and the followings unread

dasz wrote:
I use a smoother after the sequencer (usually a bit of glide or LPF)
/Dasz


Nice tip - thanks. Sorry for my endless questions but how does a LPF affect a control signal? Does it just chop off the high bits?
G2ian - thanks for the patch - will check it out as soon as I get back to my synth.

Angus
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic Moderators: Nord Modular Editors
Page 1 of 1 [12 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
 Forum index » Clavia Nord Modular » Nord Modular G2 Discussion
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


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