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MF-106 High Pass Filter

Posted: Sat Nov 15, 2014 2:09 pm
by Asymetrical
Please oh please oh please........

Please Moog build the definitive High Pass Moogerfooger!

there is no MF-106 ......

I've got Low pass filters (MF-101)

I've got band pass filter (Wah Pedals)

the only high pass filter I have is on my Allen and Heath Xone92 mixer,

how about a Moogerfooger High Pass Filter!!!!!

Re: MF-106 High Pass Filter

Posted: Sat Nov 15, 2014 3:01 pm
by Vsyevolod
MF-106 is reserved for April Fool's Day announcements.

Stephen




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Re: MF-106 High Pass Filter

Posted: Sat Nov 15, 2014 4:22 pm
by Asymetrical
I crossed the line with this post didnt I......

Re: MF-106 High Pass Filter

Posted: Sat Nov 15, 2014 7:50 pm
by MC
The MF101 can do a highpass filter. You need a CP251. You mix the dry and filtered signal, and reverse the phase on one of them. This makes the passband signal out of phase, so mixing them cancels out the passband of both dry and filtered signal leaving only highpass from the dry signal. This trick goes back to the modular days in the 1960s.

Re: MF-106 High Pass Filter

Posted: Sun Nov 16, 2014 3:52 am
by DonutDude
MC wrote:The MF101 can do a highpass filter. You need a CP251. You mix the dry and filtered signal, and reverse the phase on one of them. This makes the passband signal out of phase, so mixing them cancels out the passband of both dry and filtered signal leaving only highpass from the dry signal. This trick goes back to the modular days in the 1960s.
First time I heard about it though. Thanks MC !!

Re: MF-106 High Pass Filter

Posted: Tue Nov 18, 2014 6:18 pm
by ColorForm2113
Great pro tip MC! I've got to try that out

Re: MF-106 High Pass Filter

Posted: Tue Nov 18, 2014 6:58 pm
by bichuelo
Fantastic, thanks MC! :shock:

Re: MF-106 High Pass Filter

Posted: Tue Nov 18, 2014 9:20 pm
by ColorForm2113
Just tried out the reverse phase highpass filter trick. Works great! I love getting new patch ideas to play off of, thanks!

Re: MF-106 High Pass Filter

Posted: Wed Nov 19, 2014 9:07 am
by stiiiiiiive
I had read that on Clavia Modular's forums, but I ws not aware this very technique could work in the analogue realm.
Maybe that's because the phase inversion technique was properly digital, can't remember.

Anyway, I'll try that out too, thanks!! :)

Re: MF-106 High Pass Filter

Posted: Thu Nov 20, 2014 12:00 pm
by Alien8
Excited to try this, thanks! So many ideas just came from this patch idea, not only high pass filtering, but using the reverse phase. Always knew it was there, just never toyed with it yet!!!!

Re: MF-106 High Pass Filter

Posted: Thu Nov 20, 2014 10:23 pm
by bichuelo
MC wrote:The MF101 can do a highpass filter. You need a CP251. You mix the dry and filtered signal, and reverse the phase on one of them. This makes the passband signal out of phase, so mixing them cancels out the passband of both dry and filtered signal leaving only highpass from the dry signal. This trick goes back to the modular days in the 1960s.
Well, I am trying to do it but I don't know exactly how to reverse the phase. Could you please tell me how to patch it?

Re: MF-106 High Pass Filter

Posted: Fri Nov 21, 2014 2:03 am
by EMwhite
A 106 High pass is not a bad idea. Not sure what the market for such a pedal is but a bunch of us would sure appreciate it.

Moog has just finished making those modular clones for the 5 rich and famous people (if they were not famous before, they are now : ) so why not take some of those discovered gems and drop them into a limited edition line of Foogers.

Doing the full Modular thing will cost money and be risky, and I'm talking about spinning up power standards and connector and mounting issues, the tech support alone will be a nightmare for Moog and their guys are pretty busy most of the time [it reminds me where I work; not enough people to manage a growing list of gear to support], but my point is that if they drop a few modules into MoogerFooger clothing, and adjust input and output levels to match the rest of the Foogers and the genera Guitar or synth audience, they will do well to charge us even a premium.

Bob never got a resonant High Pass working to his satisfaction, at least not in the form of a 904b so that would be a nice add-on if it could be done without destroying the integrity of the original design.

I know that the Oberheim SEM has one of the most rich filters, in it's sweepable glory; Moog has been missing this and while you might argue, they aren't missing anything [and you would be right], adding a High Pass and the resulting Band Pass via Filter coupler would greatly enhance the sonic spectrum.

Re: MF-106 High Pass Filter

Posted: Fri Nov 21, 2014 2:36 am
by radioland
MC wrote:The MF101 can do a highpass filter. You need a CP251. You mix the dry and filtered signal, and reverse the phase on one of them. This makes the passband signal out of phase, so mixing them cancels out the passband of both dry and filtered signal leaving only highpass from the dry signal. This trick goes back to the modular days in the 1960s.
I tried out this idea last night, this is how I patched it:

Sub Phatty out --> cp251 mult in

mult out 1 --> MF101 audio in --> MF101 audio out --> cp251 mixer input 3 in

mult out 2 --> cp251 attenuator 1 in --> cp251 attenuator out (knob turned to -5 to reverse the phase) --> cp251 mixer input 4 in

The + output of the mixer then went directly to my headphones via a headphone amp.

Here are some considerations:
- Using the mult for audio results in very high noise that is added to the sound - not optimal.
- Be sure to have the offset knob in its neutral position. If not, the sound is altered and there is even more noise added.
- I found the range of the cutoff knob (fully closed = no high pass filtering, fully open = maximum high pass filtering) to be quite small. In the fully open position there still were quite a lot of low frequencies.
- You can`t work with resonance - adding resonance results in more low frequencies being added.

I grinned happily when I first heard my Sub Phatty being high pass filtered, so this is definitely a great new patch idea. But it simply can`t replace a dedicated high pass filter in my opinion.
I then tried to get resonance by adding the cp251 +mixer output (via mult on a second cp251) to the mixer input 1. It emphasized the higher frequencies, but sounded more like drive than resonance. When the knob controlling the mixer input 1 level was past the 2 o`clock setting, the output went completely crazy with high noises.

Did someone get (even) "better" results with a different patch?

Cheers, radioland

Re: MF-106 High Pass Filter

Posted: Fri Nov 21, 2014 3:01 pm
by MC
radioland wrote:But it simply can`t replace a dedicated high pass filter in my opinion.
Interesting note: that is exactly how highpass is implemented in the Voyager. I saw the schematics.

Re: MF-106 High Pass Filter

Posted: Fri Nov 21, 2014 3:06 pm
by ColorForm2113
I wish there was a way to isolate just the highpass in the Voyager. It can get close some settings with the spacing resonance and pole settings, but not quite