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
  EdisonRex Edison's Electronic Review
Please visit the chat
 Forum index » Clavia Nord Modular » G2 Patches - Completed » FX
AfroVerb v1.3
Post new topic   Reply to topic Moderators: Nord Modular Editors
Page 1 of 1 [8 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
Afro88



Joined: Jun 20, 2004
Posts: 701
Location: Brisbane, Australia
Audio files: 12
G2 patch files: 79

PostPosted: Tue Sep 14, 2004 7:52 am    Post subject: AfroVerb v1.3 Reply with quote  Mark this post and the followings unread

Following on from the discussion about reverbs on the mailing list, and Rob's excellent description of how allpass filters can be coupled with feedback delay lines for the diffusion devices in reverbs, I decided to go about creating my own reverb. Unfortunately I wasn't able to locate the ursa major manual Rob was refering to in his post, so this is the result of quite a bit of trial and error scratch.

All the main parameters are assigned to front panel knobs. Morph group 1 is room size, 2 is feedback and 3 is dry/wet ratio.

Btw, I have a cold at the moment, so the variations might sound a bit off... but they sound fine to my blocked up ears! Very Happy


AfroVerb v1.3.pch2
 Description:
A reverb patch using 4 allpass filters through feedback delay lines as diffusers

Download
 Filename:  AfroVerb v1.3.pch2
 Filesize:  4.01 KB
 Downloaded:  1229 Time(s)

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


Joined: Apr 03, 2004
Posts: 20681
Location: The Netherlands, Enschede
Audio files: 156
G2 patch files: 318

PostPosted: Tue Sep 14, 2004 8:10 am    Post subject: Re: AfroVerb v1.3 Reply with quote  Mark this post and the followings unread

Rob wrote the following on the Nord Modular mailing list (see http://mail.electro-music.com/mailman/listinfo/nord-modular for info about the list)

Rob Hordijk wrote:
An allpass filter passes all frequencies with the same amplitude, but each
frequency in the signal gets a slightly different phaseshift. This
phaseshift is also a very short time delay, so the time delay for each
frequency is slightly different.

The delay times in an allpass filter are relatively short, typically the
phaseshift is between 30 and 150 degrees of the wavecycle, which is
something like between 10% and 40% of the wavelength of that particular
frequency. Cascading four to eight allpass filters and feeding the output
back to the input creates the wellknown phaser module. Which has a delay
time that is definitely not long enough yet for a convincing reverb.

The use of an allpass filter in the feedback loop of a much longer delay
causes an effect named 'dispersion'. Imagine a delayline with a length of
e.g. 40 msec plus an allpass filter in series. The effect is that the
delaytime is slightly different for different frequencies. On each
recirculation of audio through the delay the dispersion builds up.
Dispersion is very similar to what a prism does to white light.

On the G2 an allpass filter is present in the multimode filter. If this
filter is set to 6dB and the BP output is used, the filter actually becomes
an allpass filter. Resonance should be set to minimum when the filter is
used in a delayline feedback loop and note that the allpass output is also
in anti-phase (inverted). When the cutoff frequency of the allpass filter is
slowly modulated, it introduces a lively modulation in the delay. A similar
effect can be heard quite well in the G2 Reverb if feeding it with a static
oscillator signal: you will hear a lively soft chorusing in the output
signal.

Another important effect of an allpass filter in a feedback loop of a delay
line is to prevent the delayline to resonate on a basic frequency plus all
of its harmonics. As the harmonics are shifted 'out of phase' the resonance
effect is 'smeared out' which sounds more natural.

In general allpass filters are not used on the early reflections, but
heavily used when creating the reverb tail, to make the tail disperse into
noise. I guess that not using allpass filters in the early reflections is
mostly because of savings on dsp power. As allpass filters can work out very
nicely on early reflections and create a lively 'ambiance' reverb.

These days convolution is heavily used to create reverbs. This technique
uses a recording of the reverberation of a short pulse, like a gunshot, in a
space, and from this recording it will calculate a set of static data that
will exactly recreate the reverb of the space. This method is great to
create reverbs on a master mix. Disadvantage of these convolution reverbs is
that they sound a bit static (metallic) on a single synth. Using delays plus
allpass filters enables to make the more lively reverbs that works out very
well on 'static' synth sounds but not on a master mix. But this is a vastly
different approach to convolution. It is quite a deep subject and its not at
all easy to patch a nice sounding reverberation effect. Undoubtedly it will
take a lot of experimenting before it sounds good. But the experiments will
undoubtedly yield some very interesting whacky stuff, similar to those
vintage tape reverb sounds of way back when. Which would be very nice to
share, imho there's already enough 'cathedrals' around but never enough
spooky caves and tunnels. :-)

Google 'ursa major space station'. Download the user manual and service
manual, it contains some interesting and workable approaches on the subject
that one can easily expand upon.

/Rob
Back to top
View user's profile Send private message Visit poster's website
Blue Hell
Site Admin


Joined: Apr 03, 2004
Posts: 20681
Location: The Netherlands, Enschede
Audio files: 156
G2 patch files: 318

PostPosted: Tue Sep 14, 2004 8:20 am    Post subject: Re: AfroVerb v1.3 Reply with quote  Mark this post and the followings unread

Afrokid wrote:
Unfortunately I wasn't able to locate the ursa major manual Rob was refering to in his post


Probably here : http://www.theworld.com/~cmoore/UrsaMajor_Documents.htm

Jan.
Back to top
View user's profile Send private message Visit poster's website
mosc
Site Admin


Joined: Jan 31, 2003
Posts: 17620
Location: Allentown, PA
Audio files: 125
G2 patch files: 60

PostPosted: Tue Sep 14, 2004 11:07 am    Post subject: Reply with quote  Mark this post and the followings unread

Afrokid, you are onto something here. Some of these reverbs are really choice. The Squarepuller and Randrops variations are fab. I've got some recordings of the early Dutch electronic music from the Philips Research Labs and these reverbs (some of them) sound very much like what the were using back in the 50s and 60s. They had very expensive custom-made equipment based on tape. I'ts amazing that you're patch sounds so similar.

Please, folks, if you think the G2 has a recognizable sound, lost this patch and rethink. Kid Balton would have loved this.
Back to top
View user's profile Send private message Send e-mail Visit poster's website AIM Address
ian-s



Joined: Apr 01, 2004
Posts: 2578
Location: Auckland, New Zealand
Audio files: 42
G2 patch files: 611

PostPosted: Tue Sep 14, 2004 1:26 pm    Post subject: Reply with quote  Mark this post and the followings unread

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


Joined: Apr 03, 2004
Posts: 20681
Location: The Netherlands, Enschede
Audio files: 156
G2 patch files: 318

PostPosted: Tue Sep 14, 2004 2:11 pm    Post subject: Reply with quote  Mark this post and the followings unread

mosc wrote:
I've got some recordings of the early Dutch electronic music from the Philips Research Labs and these reverbs (some of them) sound very much like what the were using back in the 50s and 60s.


Some sound examples for this music can be found at http://www.bastamusic.com/ it's the kid baltan / van dissevelt CD in the 3rd column. It's a four CD box that can also be ordered through the link supplied.

And about the effect this thread is all about : excellent, I'm going to use it !

Jan.
Back to top
View user's profile Send private message Visit poster's website
Afro88



Joined: Jun 20, 2004
Posts: 701
Location: Brisbane, Australia
Audio files: 12
G2 patch files: 79

PostPosted: Tue Sep 14, 2004 2:54 pm    Post subject: Re: AfroVerb v1.3 Reply with quote  Mark this post and the followings unread

Blue Hell wrote:
Afrokid wrote:
Unfortunately I wasn't able to locate the ursa major manual Rob was refering to in his post


Probably here : http://www.theworld.com/~cmoore/UrsaMajor_Documents.htm

Jan.


Ah, thanks Jan. I was googling for "ursa major space station" in quotes, so I must have missed that page Embarassed. I listened to some of the Kid Baltan examples, and they sound pretty mad. I'm suprised I've never heard of him before. I had a teacher at school who introduced me to all the major players of early electronic music - Kraftwerk, Jean Micheal Jarre, Art of Noise etc. He probably thought it was too weird for me to listen to at the time! Well, it sounds great!

I'm actually pretty happy with the sound of this one too, it sounds old and it sounds a bit broken. I like instruments that sound "vintage", or at least have a distinct character, and I think this fulfils that guideline. It reminds me of early Chemical Brothers stuff, the songs where they relied quite heavily on the EMS Synthi sound for their music. The reverb they use in almost every track is from the spring in the Synthi... I'm very pleasantly suprised how much this sounds like those old reverbs. Very Happy
Back to top
View user's profile Send private message Visit poster's website
mosc
Site Admin


Joined: Jan 31, 2003
Posts: 17620
Location: Allentown, PA
Audio files: 125
G2 patch files: 60

PostPosted: Tue Sep 14, 2004 4:11 pm    Post subject: Reply with quote  Mark this post and the followings unread

Yes, it sounds like the old stuff, but it's adjustable to sound like stuff that hasn't been heard before too. It's a reverb sandbox... Very Happy
Back to top
View user's profile Send private message Send e-mail Visit poster's website AIM Address
Display posts from previous:   
Post new topic   Reply to topic Moderators: Nord Modular Editors
Page 1 of 1 [8 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 » G2 Patches - Completed » FX
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