Doepfer Combi Filter
2010-11-14 by jonathan.heslop
Which Doepfer module can act as a combi filter? Is it the BBD modules? Jonathan
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Doepfer Combi Filter
Re: [Doepfer_a100] Doepfer Combi Filter
2010-11-14 by york luethje
What do you mean by 'combi filter'? A comb filter, whereby selective frequencies are filtered? ________________________________
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From: jonathan.heslop <jonathan.heslop@yahoo.co.uk> To: Doepfer_a100@yahoogroups.com Sent: Sunday, November 14, 2010 17:18:49 Subject: [Doepfer_a100] Doepfer Combi Filter Which Doepfer module can act as a combi filter? Is it the BBD modules? Jonathan [Non-text portions of this message have been removed]
Re: Doepfer Combi Filter
2010-11-14 by jonathan.heslop
Sorry, i meant comb filter. I'm getting my comb filter and combi boiler mixed up :) I have the option of a second hand AS RS-120 comb filter, just wondering what other options there are. Thanks, Jonathan --- In Doepfer_a100@yahoogroups.com, york luethje <ybl@...> wrote:
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> > What do you mean by 'combi filter'? A comb filter, whereby selective frequencies > are filtered? > > > > > ________________________________ > From: jonathan.heslop <jonathan.heslop@...> > To: Doepfer_a100@yahoogroups.com > Sent: Sunday, November 14, 2010 17:18:49 > Subject: [Doepfer_a100] Doepfer Combi Filter > > > Which Doepfer module can act as a combi filter? Is it the BBD modules? > > Jonathan > > > > > > > [Non-text portions of this message have been removed] >
AW: [Doepfer_a100] Re: Doepfer Combi Filter
2010-11-15 by York Luethje
Hi Jonathan, Any delay of sufficient time (2mS - 30mS, if I recall correctly) will create phase cancellations that result in the comb filter effect. As per their website the ASys RS120 is a BBD (delay times 2,5 - 25mS) so the Doepfer range should be able to do this as well. As to other modules, the only one I can think of is the A-128 Fixed Filterbank, but all the bands are fixed, as the name implies. _____ Von: Doepfer_a100@yahoogroups.com [mailto:Doepfer_a100@yahoogroups.com] Im Auftrag von jonathan.heslop Gesendet: Sonntag, 14. November 2010 19:40 An: Doepfer_a100@yahoogroups.com Betreff: [Doepfer_a100] Re: Doepfer Combi Filter Sorry, i meant comb filter. I'm getting my comb filter and combi boiler mixed up :) I have the option of a second hand AS RS-120 comb filter, just wondering what other options there are. Thanks, Jonathan --- In Doepfer_a100@yahoogroups.com <mailto:Doepfer_a100%40yahoogroups.com> , york luethje <ybl@...> wrote: > > What do you mean by 'combi filter'? A comb filter, whereby selective frequencies > are filtered? > > > > > ________________________________ > From: jonathan.heslop <jonathan.heslop@...> > To: Doepfer_a100@yahoogroups.com <mailto:Doepfer_a100%40yahoogroups.com> > Sent: Sunday, November 14, 2010 17:18:49 > Subject: [Doepfer_a100] Doepfer Combi Filter > > > Which Doepfer module can act as a combi filter? Is it the BBD modules? > > Jonathan > > > > > > > [Non-text portions of this message have been removed] > [Non-text portions of this message have been removed]
Re: [Doepfer_a100] Re: Doepfer Combi Filter
2010-11-15 by Florian Anwander
Hi Jonathan > Sorry, i meant comb filter. comb filters are based on the principle of phase cancelation around a certain frequency. They can be achieved by many different means: 1.) Each analog filter does a phase shift around the center frequency. For example: a multimode filter like the A121 does this: if you mix the high pass and the low pass, you will get a notch-filter, which one may regard as a single notch comb filter. If you would add several multimodefilters at different center frequencies, you would get a multi notch comb filter. 2.) This kind of a "multi notch comb filter" can be achieved more easily using several stages of so called allpass filters, which in fact do not filter at all, but they still do the phase shift around their center frequency. If you mix this "filtered" signal with the original signal you will get again a comb filter. If you modulate the center frequency of this chain of allpass filters you will get what we call a "Phaser". 3.) A different approach is the usage of a delay line. A delay will cause phase cancelations at certain frequencies, if the delay time corresponds to the wave length of this frequency. If you modulate the delaytime you will get what we call a "Flanger". These three cases differ by the position of the notches in the frequency spectrum In case #1 it depends on the different center frequencies of these filters, which could be selected free (in theory). In case #2 it is spread in linear steps over the frequencies (e.g. 200, 400, 600, 800... Hz). In case #3 the notches appear each doubling of the frequency (e.g. 200, 400, 800, 1600 ... Hz). Florian
Re: [Doepfer_a100] Re: Doepfer Combi Filter
2010-11-15 by Bakis Sirros
once again, thanks Florian for your useful and detailed reply! Bakis Sirros - Parallel Worlds / Interconnected / Memory Geist [Doepfer_a100] group owner www. parallel - worlds - music. com www. myspace. com/ parallelworldsmusic www. myspace. com/ interconnectedmusic www. myspace. com/ memorygeist www. DiN. org. uk www. musicamaximamagnetica. com www. vu-us. com --- On Mon, 11/15/10, Florian Anwander <fanwander@mnet-online.de> wrote:
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From: Florian Anwander <fanwander@mnet-online.de>
Subject: Re: [Doepfer_a100] Re: Doepfer Combi Filter
To: Doepfer_a100@yahoogroups.com
Date: Monday, November 15, 2010, 10:44 AM
Hi Jonathan
> Sorry, i meant comb filter.
comb filters are based on the principle of phase cancelation around a
certain frequency. They can be achieved by many different means:
1.) Each analog filter does a phase shift around the center frequency.
For example: a multimode filter like the A121 does this: if you mix the
high pass and the low pass, you will get a notch-filter, which one may
regard as a single notch comb filter. If you would add several
multimodefilters at different center frequencies, you would get a multi
notch comb filter.
2.) This kind of a "multi notch comb filter" can be achieved more easily
using several stages of so called allpass filters, which in fact do not
filter at all, but they still do the phase shift around their center
frequency. If you mix this "filtered" signal with the original signal
you will get again a comb filter. If you modulate the center frequency
of this chain of allpass filters you will get what we call a "Phaser".
3.) A different approach is the usage of a delay line. A delay will
cause phase cancelations at certain frequencies, if the delay time
corresponds to the wave length of this frequency. If you modulate the
delaytime you will get what we call a "Flanger".
These three cases differ by the position of the notches in the frequency
spectrum
In case #1 it depends on the different center frequencies of these
filters, which could be selected free (in theory).
In case #2 it is spread in linear steps over the frequencies (e.g. 200,
400, 600, 800... Hz).
In case #3 the notches appear each doubling of the frequency (e.g. 200,
400, 800, 1600 ... Hz).
Florian
[Non-text portions of this message have been removed]Re: Doepfer Combi Filter
2010-11-15 by jonathan.heslop
Thanks for all the replies. You answered my question and then some Florian! I think I will give the RS-120 a miss and go with the A-188-1 and A-106-6. Thanks, Jonathan --- In Doepfer_a100@yahoogroups.com, Florian Anwander <fanwander@...> wrote:
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> > Hi Jonathan > > > Sorry, i meant comb filter. > > comb filters are based on the principle of phase cancelation around a > certain frequency. They can be achieved by many different means: > > 1.) Each analog filter does a phase shift around the center frequency. > For example: a multimode filter like the A121 does this: if you mix the > high pass and the low pass, you will get a notch-filter, which one may > regard as a single notch comb filter. If you would add several > multimodefilters at different center frequencies, you would get a multi > notch comb filter. > 2.) This kind of a "multi notch comb filter" can be achieved more easily > using several stages of so called allpass filters, which in fact do not > filter at all, but they still do the phase shift around their center > frequency. If you mix this "filtered" signal with the original signal > you will get again a comb filter. If you modulate the center frequency > of this chain of allpass filters you will get what we call a "Phaser". > 3.) A different approach is the usage of a delay line. A delay will > cause phase cancelations at certain frequencies, if the delay time > corresponds to the wave length of this frequency. If you modulate the > delaytime you will get what we call a "Flanger". > > These three cases differ by the position of the notches in the frequency > spectrum > In case #1 it depends on the different center frequencies of these > filters, which could be selected free (in theory). > In case #2 it is spread in linear steps over the frequencies (e.g. 200, > 400, 600, 800... Hz). > In case #3 the notches appear each doubling of the frequency (e.g. 200, > 400, 800, 1600 ... Hz). > > Florian >