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jhaible
Joined: May 25, 2007 Posts: 2014 Location: Germany
Audio files: 24
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Posted: Thu Feb 28, 2008 1:20 am Post subject:
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I'm currently prototyping something very special that uses two 20-stage APF ladders ...
I won't tell what it is yet ... might be a huge failure ... or might be something quite unexpected ...
Give me a few days, and I'll either post sound samples, or throw it in the bin.
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f) |
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germaniac
Joined: Aug 04, 2006 Posts: 200 Location: California
Audio files: 7
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Posted: Thu Feb 28, 2008 11:10 am Post subject:
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Is it bigger than a breadbox? Is it a "Dimension"-type circuit ( dual anti-phase modulation) using all-pass stages instead of BBDs? Did I win? |
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gavgomad
Joined: Jan 29, 2006 Posts: 69 Location: Canada
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Posted: Thu Feb 28, 2008 1:30 pm Post subject:
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Hmmmn.... APFs.... 2x20 suggests stereo, but the APFs throw me.... I know many moons ago JH was pondering a vocoder, but APFs clearly won't get you there....
Hmmmmmnn... Stereo 20-Band Vocoding with offsets between the channels for a stereo "width" control.... ;-P
Of course total nonsense, but fun to ponder!
G |
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jhaible
Joined: May 25, 2007 Posts: 2014 Location: Germany
Audio files: 24
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Posted: Thu Feb 28, 2008 2:26 pm Post subject:
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germaniac wrote: | Is it bigger than a breadbox? Is it a "Dimension"-type circuit ( dual anti-phase modulation) using all-pass stages instead of BBDs? Did I win? |
Well, that wasn't so hard to guess, was it?
As I've stepped back (at least until June) for a real Dim D emulation, I'm trying something different yet similar.
Now that the Tau reiusse is under way, I've taken my last reserve boards of the first batch and partly populated them with a straight APF line plust preemphasis / deemphasis, and I'm going too hook this up with the filter circuitry and modulation LFO of the Dimension D on breadboard.
I'm really, really curious how close this will be, and if it's usable at all.
If it's good, I have plans to make a PCB for that.
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f) |
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gavgomad
Joined: Jan 29, 2006 Posts: 69 Location: Canada
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Posted: Thu Feb 28, 2008 2:30 pm Post subject:
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VERY cool stuff JH! Looking forward to the results of this mad experiment!
Germaniac scoops it again!
Gav. |
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germaniac
Joined: Aug 04, 2006 Posts: 200 Location: California
Audio files: 7
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Posted: Thu Feb 28, 2008 3:19 pm Post subject:
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jhaible wrote: | germaniac wrote: | Is it bigger than a breadbox? Is it a "Dimension"-type circuit ( dual anti-phase modulation) using all-pass stages instead of BBDs? Did I win? |
Well, that wasn't so hard to guess, was it? |
Oh, now I feel sorry I spoiled the surprise.
Honestly I've imagined before that something like it would work, and as I mentioned, the inimitable Mr. Stites actually got as far as rigging something provisional up to test it. It was also in the back of my mind when I bought two Tau phaser boards. But as for actually getting my feet on the ground and my hands on the work (not to mention having the mental horsepower to really perfect it), I rather think you, JH, will be able to see it through. Quote: |
. . . a straight APF line plust preemphasis / deemphasis, and I'm going too hook this up with the filter circuitry and modulation LFO of the Dimension D on breadboard.
I'm really, really curious how close this will be, and if it's usable at all.
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Looking forward to hearing your experiments whatever they be!
Regards,
Joe |
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jhaible
Joined: May 25, 2007 Posts: 2014 Location: Germany
Audio files: 24
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Posted: Thu Feb 28, 2008 4:24 pm Post subject:
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germaniac wrote: |
Honestly I've imagined before that something like it would work, and as I mentioned, the inimitable Mr. Stites actually got as far as rigging something provisional up to test it. It was also in the back of my mind when I bought two Tau phaser boards. |
I know that long APFs make a good vibrato (at the moment, I have my own Tau hooked up as a vibrato for my Wurlitzer piano), and that Voce have built their "Spin" Leslie simulator around all pass filters.
So I'm sure it will work as a chorus somehow.
What I'm curious about is - given that the Dim D is a very subtle effect - whether the subtle differences to a BBD's frequency independent delay will ruin the effect or not.
Most of the veroboard stuff is done. I'm going to finish early today (now ...), as I'm on a business trip early in the morning. Maybe I have some results after the weekend.
JH.
Now playing: Vangelis, The City. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f) |
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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
Audio files: 3
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Posted: Thu Feb 28, 2008 5:28 pm Post subject:
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I'd bet that it will work. Or at least be "interesting"
Edit: If it works, would (pairs of) the existing Pipe boards be potential hosts for a "modulation sidecar", a sort of add-on directly derived from the Dimension D, or would the continuously-variable nature of the Pipe preclude it from such use?
Good call Juergen. This is an interesting direction. |
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jhaible
Joined: May 25, 2007 Posts: 2014 Location: Germany
Audio files: 24
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Posted: Thu Feb 28, 2008 11:42 pm Post subject:
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Peake wrote: | I'd bet that it will work. Or at least be "interesting"
Edit: If it works, would (pairs of) the existing Pipe boards be potential hosts for a "modulation sidecar", a sort of add-on directly derived from the Dimension D, |
You could certainly hack a Dim D and put two Tau boards in there - but who would do that if he has an original ?
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f) |
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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
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Posted: Fri Feb 29, 2008 2:45 am Post subject:
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Hee hee, you purposely misunderstand me.
To reiterate, why not build a Dimension D modulation source clone, if the Pipe flangers would provide sufficient delay times? You would of course have to dial in the sweet spots on your own, but many of us have two Pipes, and there are more on the way (yahoo!).
I'd build a "D" clone, even if it were not a true clone, as I'm thinking that you'd get a better SNR with allpasses than with companded BBDs, am I correct? I'm very interested in your results, and am merely positing the possibility for those of us with two Pipes to attain the "D" character. I definitely bought two for stereo use, so...
I'm not trying to be difficult, but I don't know of any smoother method to share my concepts and questions.
Edit: Wait, isn't there also some sort of EQ thing going on in the "D"? I'm going to break out the schemos... Last edited by Peake on Fri Feb 29, 2008 11:42 am; edited 1 time in total |
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funkyfarm
Joined: Jan 21, 2007 Posts: 583 Location: France
Audio files: 3
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jhaible
Joined: May 25, 2007 Posts: 2014 Location: Germany
Audio files: 24
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Posted: Fri Feb 29, 2008 11:57 am Post subject:
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Peake wrote: | Hee hee, you purposely misunderstand me. |
You overestimate my capability to understand things so early in the morning.
Quote: | To reiterate, why not build a Dimension D modulation source clone, if the Pipe flangers would provide sufficient delay times? You would of course have to dial in the sweet spots on your own, but many of us have two Pipes, and there are more on the way (yahoo!). |
Ok, now I understand.
I thought about doing something like that at first. But that would require all who want the "Dimension P" ("P" as in Phase) to buy 3 boards.
My next idea to make use of the otherwise unused PCB patterns of two partly populated Tau boards, to create the required filters and the modulation source.
But it's way more efficient (i. e. cheaper for the buyers) to make a completely new PCB, with the whole Dimension P circuit on it.
If the effect turns out to be good, I expect to sell as many as I sold Tau boards. If it doesn't sound like a Dimension, it's probably not worth making PCBs for.
Quote: | I'd build a "D" clone, even if it were not a true clone, as I'm thinking that you'd get a better SNR with allpasses than with companded BBDs, am I correct? |
You're being optimistic.
With some luck, a Dim P without compander will have similar , or just slightly wore, SNR than a Dim D with compander.
So I try to find out wheter I need a compander or not.
Quote: | Edit: Wait, isn't there also some sort of EQ thing going on in the "D"? |
Yes, a lot of different filter stages in here.
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f) |
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jhaible
Joined: May 25, 2007 Posts: 2014 Location: Germany
Audio files: 24
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Posted: Fri Feb 29, 2008 11:59 am Post subject:
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funkyfarm wrote: | Hi,
I'm afraid I didn't catch the procedure about GAIN trimmer... what is it for ?
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It's mainly in there because the original has one.
IMO you can simply replace it with a piece of wire.
Twenty stages.
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f) |
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gavgomad
Joined: Jan 29, 2006 Posts: 69 Location: Canada
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Posted: Fri Feb 29, 2008 1:31 pm Post subject:
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Hey all!
jhaible wrote: | But it's way more efficient (i. e. cheaper for the buyers) to make a completely new PCB, with the whole Dimension P circuit on it.
If the effect turns out to be good, I expect to sell as many as I sold Tau boards. If it doesn't sound like a Dimension, it's probably not worth making PCBs for. |
I must admit that I like the idea of a one board solution. To be truthful, although it is a cool piece of kit, the Tau on its own didn't put me over the edge enough to buy a board. This idea if it works, however, is very promising.
With or without companding, we have a number of building blocks which can be used for a really fantastic processor. Two 20-Stage ladders from the Tau design, the stereo filtering of the Dim-D, and an anti-phase modulation source for the stereo field.
Now, a question which may be silly, followed by some random thinking aloud (which could be even sillier ....)
Do the all-pass stages actually result in a delay? If so, and the delay times are adjustable (I realize the delay times would not come close to a BBD), then if I understand, the effects could range from a stereo flanger, to stereo phaser, to dimension chorus effect.... The filtering stages could be switched in or out, the modes could be switched as well so that the controls have the appropriate range for the given effect (be it phasing, flanging or chorusing).
Just trying to understand the possibilities of this circuit.... Again, pending JH's seal of approval as to whether or not this works (I promise not to get TOO ahead of myself! ;-P)
Gav. |
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germaniac
Joined: Aug 04, 2006 Posts: 200 Location: California
Audio files: 7
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Posted: Fri Feb 29, 2008 2:00 pm Post subject:
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gavgomad wrote: |
Do the all-pass stages actually result in a delay? If so, and the delay times are adjustable (I realize the delay times would not come close to a BBD), then if I understand, the effects could range from a stereo flanger, to stereo phaser, to dimension chorus effect....
Gav. |
". . . .Ah, Grasshopper, you have asked the Great Question, but are you now prepared to enter the Path Of Many Possiblities? . . ."
Delay indeed! But with one distinction (of which I leave better minds to clearer explanations), that the delay is frequency dependent: in other words, instead of a given number of mS across the whole audio spectrum, the APF delays a given frequency range more (a notch in the spectrum) and the rest of the range lesser and lesser or not at all. The reason a twenty-stage filter sounds so intense is that you have MANY notches (exactly ten, IIUC) across the frequency spectrum being delayed. So, welcome to the world of APF Possiblities, limited only by your imagination and your willingness to split, cross-mix, anti-phase modulate, twist, contort, and otherwise exploit as many phase stages as you can chain together! Go mad Gav!
Quote: | The filtering stages could be switched in or out, the modes could be switched as well so that the controls have the appropriate range for the given effect (be it phasing, flanging or chorusing). |
PAGING SCOTT STITES!
Regards,
Joe Last edited by germaniac on Fri Feb 29, 2008 2:12 pm; edited 1 time in total |
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gavgomad
Joined: Jan 29, 2006 Posts: 69 Location: Canada
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Posted: Fri Feb 29, 2008 2:11 pm Post subject:
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Ah, yes Master. I see....
What is the sound of one hand tapping....
....into any given point in a monster ladder of all-pass filters?
Didn't our friendly resident moderator almost go MAD ( ) toying with such ideas in his multi-stage phaser?
Let's not put too much pressure on JH on this one.... I think we all have a vested interest in keeping him sane and healthy!
If this idea works, however, the possibilities seem to be mind boggling - far beyond what even I was suggesting, depending on how modular the board was set up vis a vis taps etc....
We wait with baited breath for JH's verdict....
Gav. |
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germaniac
Joined: Aug 04, 2006 Posts: 200 Location: California
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Posted: Fri Feb 29, 2008 2:33 pm Post subject:
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gavgomad wrote: | Ah, yes Master. I see....
What is the sound of one hand tapping....
....into any given point in a monster ladder of all-pass filters?
Didn't our friendly resident moderator almost go MAD ( ) toying with such ideas in his multi-stage phaser?
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Yes, but it was the madness of ecstatic creativity! The thing sounded/sounds awesome, but when he started running control wires under his bed and along the rain gutters of his house, I think he realized it was time to get some perspective. That said, I do hope he'll pop in here eventually just to set the record straight. . . .
You mentioned the sound of one hand tapping; an idea I brought up before, which I got from studying a Tom Scholz reverb circuit, was to send every other tap of a long phase-network left and right alternately. The stereo imaging possibilities of this (I hypothesize) are even greater than with a Dim D/C, but I haven't proven this out yet, and don't remember exactly the results Herr Stites found. The tempting possibilities remain undiscovered. . . .
Regards,
Joe |
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Scott Stites
Janitor
Joined: Dec 23, 2005 Posts: 4127 Location: Mount Hope, KS USA
Audio files: 96
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Posted: Fri Feb 29, 2008 6:08 pm Post subject:
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Go mad? Don't mind if I do!!! Woop woop woop.....
This must be in reference to my mothballed MultiPhase project. It comprised of 32 stages of Vactrol controlled phase shift (two 16 stage sections that could be configured in stereo or cascade up to 32 stages). It was tappable, like the old Moog stage phaser. Every two steps there was a tap for both the phase chain and the point from which the regeneration signal could be taken. Both the signal input and the regen input could be switched for either stage 1 or stage 2. This was so that, even though the taps were on even numbered stages, the total number of stages could be even or odd, which often made an amazing difference in the sound of the thing.
I rigged up also a cross-regeneration path. In other words, the regenerative signal from one set of 16 stages could be injected into the other chain and vice versa. Again, this often had a remarkable effect on things. I'd also rigged THAT VCA based soft knee compressor/limiters in the regen path, which kept the regen under a fairly buttery control.
Even though the phase shifter has a huge number of stages, I don't think it would ever be capable (at least as I designed it) of creating that over-the-top sound JH has captured from the original Tau. I think one reason may be that the phase shift created by Vactrols doesn't march in the lockstep that the Tau does. In exchange for that, though is that it can only be described as a very gooey multi-stage phase sound - it can be intense, but is not nearly as focused as the tau. And it certainly could bend the frequencies to its heart's content. It's been in mothballs a couple of years, but someday I'll resurrect it. A zillion samples and details of it can be found here:
http://mypeoplepc.com/members/scottnoanh/birthofasynth/id18.html
To the issue at hand - please correct me if I'm wrong, but I think a phase shift network could only go so far in recreating a dimension effect. If I'm not mistaken, I think the amount of perceived pitch bend for a given amount of phase shift is frequency dependent - IE, low notes may bend less than high notes or vice-versa, whereas a BBD is always going to bend things uniformly. That's not to say don't go for it - (a) I could be totally wrong and (b) if I'm not wrong, who's to say it wouldn't sound absolutely groovy in an unexpected way?
I did dally with the concept briefly, expecting to return to it but never quite did. I recorded a sample of sixteen stage per channel stereo phase shift bending a very simple patch on my DW6000. The phase shift channels are modulated antiphase by a triangle signal, and there is no regeneration. The signal in is mono, and the sample starts out with the dry signal before the phase shifter is kicked in.
http://mypeoplepc.com/members/scottnoanh/sitebuildercontent/sitebuilderfiles/16_16_ster_anti_tri_1.mp3
Sort of dimension-like, it is, but there's still a bit more movement there. In any event, it certainly is not the effect that one would associate with a phase shifter. Who knows what results one would get if one faithfully reproduced more of the original Dimension path - IE, the filtered crossmixing?
Mike - if you decide to join a couple of Tau's together, try experimenting with cross regeneration. I'm uploading a sample that has some samples I took with cross-regeneration. The recording is just the DW6000, with purposeful "plain" un-modulated patches. All of the modulation and effect is the Multiphase (any the percussion heard is the Multiphase being thwacked withhard edged waves while in high regen). I never posted it before, because it was recorded all that well, and my many-thumbed hands are ever so apparent.
Actually what made me think of this sample was JH's comment about using phase shifters for organs - a capital idea. At the very end of this sample the Multiphase is turning an unmodulated synth tone into a not half-bad organ. There are more cross-regeneration samples on the link above, along with some other doodads I was throwing into the MultiPhase sink.....
Cheerio,
Scott
Description: |
Multiphase Cross-Regeneration |
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xgen_snippets.mp3 |
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_________________ My Site |
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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
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Posted: Fri Feb 29, 2008 9:55 pm Post subject:
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Scott wrote: "it can only be described as a very gooey multi-stage phase sound - it can be intense, but is not nearly as focused as the tau."
Both are equally desirable for their intrinsic character.
Those are some nice soundclips. I too look forward to Juergen's discoveries along these lines of inquiry... |
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jhaible
Joined: May 25, 2007 Posts: 2014 Location: Germany
Audio files: 24
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Posted: Sat Mar 01, 2008 2:32 am Post subject:
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Scott,
your samples are wonderful, as is the whole concept of using long vactrol-based phase shift lines and all sorts of feedback and cross-feedback.
This could be the center of a "modular" phaser approach, with a matrix (other means of patching) for almost unlimited experiments.
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f) |
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jhaible
Joined: May 25, 2007 Posts: 2014 Location: Germany
Audio files: 24
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Posted: Sat Mar 01, 2008 8:57 am Post subject:
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Scott Stites wrote: |
To the issue at hand - please correct me if I'm wrong, but I think a phase shift network could only go so far in recreating a dimension effect. If I'm not mistaken, I think the amount of perceived pitch bend for a given amount of phase shift is frequency dependent - IE, low notes may bend less than high notes or vice-versa, whereas a BBD is always going to bend things uniformly. |
Right. Looking at the group delay plot of a long all pass filter, I see a rather flat part in the middle, with the group delay rising insanely towards low frequencies, and gently falling towards higher frequencies.
Now, in the Dimension D the whole delay path is high pass filtered. Same-channel feed and cross-channel feed of the delay path are filtered differently, but it's always high pass filtered. And the direct (undelayed) path has a slight bass boost to compensate for this, to give the impression of an overall equal frequency response. That means, chorusing doesn't take place in the bass, which helps to keep the directness of the processed signal. My hope is that it also helps to make the rise of group delay in the bass with the phase shifter method less relevant.
In the high range, there will be a difference in the distribution of notches, no doubt. But as this is no flanger, where the notches are made prominent by carefully balancing direct and delayed signal, there is hope as well: In a chorus, the frequency modulation is the main thing, and the delayed signal is mixed weaker than the direct signal in 3 of the 4 modes anyway.
More later ...
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f) |
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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
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Posted: Sat Mar 01, 2008 11:27 am Post subject:
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Haha, it IS a crossover chorus.
Those Roland engineers certainly got things right, back in the day. |
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jhaible
Joined: May 25, 2007 Posts: 2014 Location: Germany
Audio files: 24
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Posted: Sat Mar 01, 2008 4:03 pm Post subject:
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Well ... after some playing around with the trimpots ... I think it's possible to create subtle, chorus-like effects, but it doesn't sound like a Dimension D.
Maybe the delayed pat is too high in the mix (I'll have to check this later, resolder something), but probably it#s just too phaser-like.
Hear for yourself.
I have made a longer recording, but then I found converting it to mp3 ruined the sound completely by adding a stupid, aliasing-like noise. So here is a wav file, but a very short one. Starting with the dry signal, then switching the effect in.
JH.
Description: |
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dim_tau_1_r8b_trim.wav |
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2.26 MB |
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1194 Time(s) |
_________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f) |
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v8pete
Joined: Jan 27, 2008 Posts: 43 Location: UK
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Posted: Sat Mar 01, 2008 4:48 pm Post subject:
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That's not half bad Jurgen - I hear what you mean about it sounding slightly "phasy", but nevertheless a very pleasant effect in its own right.
Pete. |
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Scott Stites
Janitor
Joined: Dec 23, 2005 Posts: 4127 Location: Mount Hope, KS USA
Audio files: 96
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Posted: Sat Mar 01, 2008 5:59 pm Post subject:
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Oh, my that is a beautiful effect. _________________ My Site |
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