16 stage vactrol phaser (link) w/samples

[Paul Perry (Frostwave)]

http://mypeoplepc.com/members/scottnoanh/birthofasynth/id18.html

Just found this at synth-diy...... check the breadboard

[The Tone God]

check the breadboard

I have two projects right now on the work bench that are in the same league or better. Fun stuff.

Andrew

[R.G.]

Any time I get over 8 stages per line, I always want to split into approximately equal phase lines and modulate them differently. Coherent modulation, at offset phase like out of phase LFO, quadrature, three phase, etc, always sounds interetsting, but so does almost-but-not-quite synched sines and integer-multiple related LFOs. Random is downright quirky.

It's really trivially simple - you just gots to make lots of stages.

[DiyFreaque]

Any time I get over 8 stages per line, I always want to split into approximately equal phase lines and modulate them differently.

Me too, except this one got to be more than 8 stages per channel - it's actually 16 stages per channel, 32 stages cascaded (if one so chooses) 

It's set to be configurable so that each channel can be up to 16 stages.  They can range anywhere from 2 to 16.  Each channel has its own control circuitry, or both can be driven off the same source.  Regeneration is selectable between inverted and non-inverted, and can also be even or odd number of stages (selected from even stages and inserted into either the first or second stage, and regen of course can span all 32 channels, too, when cascading sections).   I'm using a THAT Corp soft-knee compressor/limiter on each 16 stage sections's regen line, parts courtesy of Small Bear - thanks for stocking them, Steve!!

I played with a three phase lines before arriving at this, but it always sounded a bit 'busy' to my ears (I was hoping it would be more PS31000 resonator like).  Prolly shoulda tried a 3 phase LFO, but never got round to that.

I have a couple of things more to add to it, yet.....problem I'm facing now is feature creep.

There's more about it at Electro-Music Forum here:

http://www.electro-music.com/forum/topic-10615.html

Cheers,
Scott

[gez]

http://www.rapidelectronics.co.uk/rkmain.asp?PAGEID=80010&CTL_CAT_CODE=&STK_PROD_CODE=M29451&XPAGENO=1

[puretube]

TUBE-PHASER ^(R)

3rd board with 8 additional stages not shown...



all NOS Siemens goldpin (mojo!) E88CC (6922);

will be mounted in 19" rack (2 units high)

[StephenGiles]

....and I'm visiting my 95 year old Mother in law this afternoon, so I'll ask for her views on the subject

Wonderful stuff, what more could a chap ask for?

[StephenGiles]

But how does it sound with straight guitar I wonder? Mike - where are you? What are your views on the subject?

[StephenGiles]

Any time I get over 8 stages per line, I always want to split into approximately equal phase lines and modulate them differently. Coherent modulation, at offset phase like out of phase LFO, quadrature, three phase, etc, always sounds interetsting, but so does almost-but-not-quite synched sines and integer-multiple related LFOs. Random is downright quirky.

It's really trivially simple - you just gots to make lots of stages.

I think that perhaps an instrument on it's own, at home, will sound good through a fancy phaser like this. In a band situation though, I'm not convinced it would sound any better than something like a Badstone, being part of an overall sound. I found this with my ADA Flanger, especially on the almost TZF setting which sounded fabulous at home through headphones, but tended to get lost as part of an overall band sound - maybe I wasn't loud enough!!!

[Mark Hammer]

I'm basing this opinion on samples of Mike Irwin's 24-stager and 16-stager (hey, a person could do a LOT worse for benchmarks!), but my impression is that for guitar purposes one starts to run out of discernible impact on tone after about 12 stages.  That's not to say that anything more than 12 stages is not good for *something*, but that something is more likely to be a synth that a guitar.

Why?

Simple.  A notch is only as audible as the bandwidth provided to it.    Humbucker pickups, overwound single-coils, and guitar speakers rarely extend much beyond 6khz bandwidth before experiencing a stark dropoff (there IS content, but it's likely about 40db lower).  If the device sweeps down to 200hz, then the next notch is at 400hz, then 800hz, 1600hz, 3200hz, 6400hz.  That's 12 stages worth of phase shift.  Sounds like a million bucks, but 16 stages and 24 stages probably sounds like about $1,000,001.29 if applied to a guitar.  The samples Mike played me sound fabulous, BUT they are applied to a very harmonically rich synth-generated chord or noise signal.  I'm guessing that Scott's samples sound just as good (not enough bandwidth over this modem connection to load them without tieing up the phone for days), but I'm also guessing that they are applied to a similarly wide bandwidth signal.

Now, try to imagine what happens as it sweeps upwards.  It doesn't take very long for the upward sweep to start losing notches as the higher ones disappear into that zone where there is nothing to filter.  Those extra stages essentially evaporate.  Could they be useful if one was phasing, say, a fuzzed guitar into a direct box and a mixing board?  I suspect yes.  Again, the principle is that if the bandwidth is there for filtering, the filtering will be heard.

Without wishing to rain too much on this particular parade, I will simply note that flangers sound the way they do because of the change in number of notches as it sweeps downward.  Not only are the notches more audible at the lowest points in the sweep cycle (i.e., the longest delay created by the BBD), but they are most plentiful as well.  I may be deluded here, but my personal view is that part of the drama of flanging is that the sound becomes "infected" wth an increasing number of notches as the sweep moves downward, and then "purified" as the sweep moves upward and the resonances are reduced in number.  Part if why phasers do not sound like flangings is that when there are only a handful of notches created (many stompboxes tend not to exceed 8 stages, though there are a few exceptions), the dips and peaks tend to be more focussed, and less distributed across the spectrum.  Moreover, while not all notches are audible at the highest point in the sweep, they do not increase in number during the downsweep as substantially as they do with flangers.  HOWEVER, when the number of notches/stages is large (e.g., 12 notches from 24 stages), fewer of them are audible at the highest point in the sweep, and the contrast in notch quantity between highest and lowest sweep points can become substantial.

That is the long way of saying that the sound of such ambitious phasers starts to approximate the sound of flangers, minus the audible doubling that flangers introduce.

[DiyFreaque]

This project is not intended for guitar nor is it a stompbox  - that's why I haven't posted anything here (though I suppose the same could be argued about my Dim C project - its input structure certainly is not guitar-friendly). 

Neither is this project intended to emulate a flanger - a flanger would be much less top-heavy in circuitry, and, as we all know, even with this number of stages, the spacing of the notches and peaks and resulting timbre will differ - yes, it is approximate to some degree, but still different enough that I would never mistake it for a flanger.  Nor is it designed to be 'fixed' at any number of stages.  It is actually two separate phase shifters in one unit, joined at the hip through selectable signal paths and common control of individual control circuitry.  It will render anything in the range of 2 to 32 stages, even or odd number of stages, inverted or non-inverted regen, modulated stages through fixed stages or vice versa.  BTW, Mark - the whole even/odd number of regeneration stages point was lost on me until I read a post of yours a while back - I'm very glad you brought that up.   

If one escapes from the paradigm that the notches have to sweep all the way up and all the way down, I think a guitar could sound smashing through it.  If one were to say center the notches a wiggle them back and forth a slight bit, I think one would be surprised.  The perceived effect is *not* the same as performing the same stunt with a flanger.  The word 'gooey' comes to mind.  In fact, crazy as it sounds, one can almost attain a chorus-like effect with it with some settings.  The pitch bending is out of this world.  It cannot actually 'double' like a flanger, but I'll be damned if it doesn't actually sound like it does at times.

At the lower end of the Vactrol's range (and the sweep range), at least with this design, is a whole crop of notches and peaks that will do very strange things with the tone (a product of what Mark is talking about with number of peaks/notches on the high end versus low).  You can hear them 'marching past', every last one.  The effect is disconcerting and rubbery at the same time. 

The number of stages is not a gimmick - it's come from a natural progression of experimentaton that started last July.  I arrived at 32 stages because 16 stages is the max my control circuit will drive efficiently. The idea was to have the max number of notches and peaks per channel I could get in stereo.  Be that as it may, I have never experienced the class of effects that I've run into with this phase shifter at 32 stages, and I'm certainly glad it can do that.  It's  overwhelming - there are so many things one can do, I'm a bit paralyzed as to what to post for samples.

The evolution of the thing is documented much better at the Electro-Music than it is at my own site.  It sort of started with this thread:

http://www.electro-music.com/forum/topic-10024.html

Some spiffy discussion of phasers occurs there.

It progressed to this thread:

http://www.electro-music.com/forum/topic-10615.html

A number of samples of it and discussion of why things are the way they are with it are contained in both.

Oh, and Ton, you have tubified yourself to even greater heights - I *love* it.  The sweetest sounding phaser I ever heard was a tube phaser.  In Germany, no less 

Cheers,
Scott

[puretube]

well, I only picked up in time, where others left the sinking ship 50-40 years ago...

nowadays a lot jump into the water & try to crawl back against the tide... but can`t hardly swim 

You said it nicely: "sweetest sounding"

(like for me) tube sound doesn`t neccessarily say: "better",

it just says: "tube..."

[DiyFreaque]

Kinda interesting, thought I'd post it. 

Last night I messed around a bit with two 16 stage sections modulated antiphase by a triangle wave, split into two channels for stereo.  There's just enough modulation to give each channel a little bit of freq bend.  It's not a Dim C, but again it doesn't sound like your normal phase shifter - there's certainly a bit of a chorus-sounding element there. 

I posted a sample of it over at the Electro-Music forum - just the DW6000 straight into the breadboarded MultiPhase into the recorder (no other effects used).  Here's a link to the sample (640 kB).

http://www.electro-music.com/forum/download.php?id=4646

It's in this thread:

http://www.electro-music.com/forum/topic-10615.html

Cheers,
Scott