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 Forum index » DIY Hardware and Software
hammond scanner vibrato? what is it?
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loss1234



Joined: Jul 24, 2007
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PostPosted: Tue Apr 29, 2008 4:08 am    Post subject: hammond scanner vibrato? what is it? Reply with quote  Mark this post and the followings unread

can anyone here shed some light on this? what is a scanner?
i have been trying to find a way to incorporate vibrato into my synth for organ type sounds but it seems to be more rare than i had thought.

thanks

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-------------------------------------------- check out various dan music at: http://www.myspace.com/lossnyc
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RF



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PostPosted: Tue Apr 29, 2008 4:44 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi loss -
I don't know what the 'scanner' you mention is - but for the Hammond organ "leslie" type of sound, MFOS has a module that will simulate that.
For simple vibrato, you can run your lfo thru an attenuator then into the CV input of your VCO...at least that's how I do it.
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Wout Blommers



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PostPosted: Tue Apr 29, 2008 4:53 am    Post subject: Reply with quote  Mark this post and the followings unread

http://theatreorgans.com/hammond/faq/hammond-faq.html wrote:
1.3 Hammond Vibrato
Provided on the organs so equipped are vibrato and chorus settings V1,V2,V3 and C1,C2,C3.

Vibrato is the periodic raising and lowering of the pitch, and is thus fundamentally different from tremolo which is a variation in only the loudness of the pitch. The Hammond vibrato is implemented using a tapped delay line, really a low-pass filter. The signal is applied to the delay line and a rotating scanner, attached to one end of the tone generator assembly, picks the signal off of the delay line at the tap points. The scanner, a single-pole 16-throw air-dielectric capacitor switch, is wired so that the tap point will traverse the entire delay line twice, once up the delay line and once back down, for each scanner rotation. As the delay line is traversed phase is added-to and then subtracted-from the signal.

The chorus signal is produced by adding non-pitch-shifted signal to the pitch-shifted signal.

The three settings each of vibrato and chorus correspond to different amounts of total delay thus different amounts of total pitch shift.

In addition to the pitch shifting function, the vibrato, as implemented in the Hammond organ, also acts as a sweeping low-pass filter. There is some frequency response and amplitude variation as the tap point of the filter is swept.

1.4 The Scanner
The scanner is used in the organ as a single-pole 16-throw rotary switch. It is constructed as a multi-plate air-dielectric capacitor with 16 stator poles and one rotor. It is used, in conjunction with the vibrato delay line, to create the chorus/vibrato.

Wout
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loss1234



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PostPosted: Tue Apr 29, 2008 4:54 am    Post subject: Reply with quote  Mark this post and the followings unread

thanks
yeah i know how to do VCO vibrato, but id like to have a classic vibrato module. maybe there isnt much of a difference?

anyway, i will look into the ray wilson module too!

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Chet



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PostPosted: Tue Apr 29, 2008 5:01 am    Post subject: Reply with quote  Mark this post and the followings unread

You can simulate a Hammond chorus/vibrato circuit with an eight-stage delay line, an eight-input crossfader, and a triangle LFO.

The delay line lengths are fixed. The eight outputs are fed into the crossfader, and the crossfader is swept by the LFO. The crossfader alone produces the vibrato effect; mixing it with the original signal produces the chorus.

The lengths of the delay line are pretty critical. The sweet spot isn't very wide.
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Wout Blommers



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PostPosted: Tue Apr 29, 2008 5:03 am    Post subject: Reply with quote  Mark this post and the followings unread

It would be fun for a DIY project Smile

http://www.curtcass.com/hammond/

and the picture of the disign...

Wout


scanner.jpg
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HJammond scanner
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scanner.jpg


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RF



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PostPosted: Tue Apr 29, 2008 5:31 am    Post subject: Reply with quote  Mark this post and the followings unread

That's very cool. Thanks for posting that drawing. There is no chance I will ever try to DIY something that mechanical. It would make me insane.
mad, short circuit

bruce
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bearblock



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PostPosted: Tue Apr 29, 2008 7:03 am    Post subject: Reply with quote  Mark this post and the followings unread

http://www.electro-music.com/forum/topic-19217.html
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frijitz



Joined: May 04, 2007
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PostPosted: Tue Apr 29, 2008 7:21 am    Post subject: Re: hammond scanner vibrato? what is it? Reply with quote  Mark this post and the followings unread

loss1234 wrote:
can anyone here shed some light on this? what is a scanner?
i have been trying to find a way to incorporate vibrato into my synth for organ type sounds but it seems to be more rare than i had thought.

thanks


Here's the page on the JH emulator.

http://jhaible.heim.at/scanner_vibrato/jh_scanner_vibrato.html

I have to say that when I visited his studio, this unit was something that really jumped out as special.

Very Happy

Ian
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loss1234



Joined: Jul 24, 2007
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PostPosted: Tue Apr 29, 2008 8:05 am    Post subject: Reply with quote  Mark this post and the followings unread

thanks a lot

ian-coming from you, that makes me think it must be great!

thanks all for the great info (as usual)

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-------------------------------------------- check out various dan music at: http://www.myspace.com/lossnyc
http://www.myspace.com/snazelle
http://www.soundclick.com/lossnyc.htm http://www.indie911.com/dan-snazelle
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Blue Hell
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Joined: Apr 03, 2004
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PostPosted: Tue Apr 29, 2008 5:46 pm    Post subject: Reply with quote  Mark this post and the followings unread

Chet wrote:
The delay line lengths are fixed.


But when they are not and you apply feedback over the delay lines as well you'll get some instant subotnicks Exclamation

edit: attached an NM G2 patch, playable in the G2 demo software and a couple of blips it made.


is-001.mp3
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is-001.pch2
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 Filename:  is-001.pch2
 Filesize:  2.45 KB
 Downloaded:  955 Time(s)


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