Your favorite Phase project?

[petemoore]

  Ok..media players got the troubles.
  About time to get the 90 out again and see what I can figure out went wrong this time...I've been using the SS w/treadle speed pedal with Jfet boost [wah case], nice pedal, have to fix that Ph90 now though..
  Decided to let the quick fix do the trick for now, again...hopefully the added insu-sheet on the bottom [which seems to suddenly allow it to be k nocked about and work uninteruptedly]. Sweet Sweep to it for sure, 'Vibe-90' [somewhere between] capacitor values have always sounded great in this one.

[DougH]

The Ross Phaser (Ropez project at www.tonepad.com) is a good 4-stage phaser that can be modified in lots of interesting and useful ways. Best of all, the LM13600 chips it uses require NO MATCHING or testing.

Mark, what do the Phase Filter switches do?

[Mark Hammer]

You can read more about the original inspiration for it here: http://hammer.ampage.org/files/Device1-6.PDF

By making two stages swept lowpass, what you get is an LFO-modulated autowah with a rolloff just above where the notch produced by the remaining 2 stages is located.  When wet and dry are combined, the effect is what Craig Anderton called an "animated" sound rather than an obvious notch sweep.  personally, the cool stuff enters for me when the dry is cancelled and you have only the 2-allpass/2-lowpas signal.  It produces a fascinating mélange of vibrato (from the 2 allpass alone), autowah (from the 2 lowpass), and tremolo (from the signal loss occurring as a result of a notch and moving treble rolloff).  Set just right, it is a really sultry effect.  Think the sexiest sweatiest version of Slim Harpo's "Baby, Scratch My Back" that you've ever heard ( http://www.youtube.com/watch?v=8tWQ6xITMT8&feature=related ) and that's the sound (though that cowbell kicks ass...).  Does really nice things for heavily distorted chords that you hold for a while.

After living with it for a while, I've come to prefer an arrangement where the cap values used for the lowpass/phase-filter stages are slightly lower than those for the allpass stages.  Iaresee borrowed one of mine, and in that one I used the standard 3300pf for the allpass stages, and 3000pf for the two lowpass stages.  If one was modding a Small Stone, then I guess a combnation of 6800 and 5600pf might be okay.  The idea is that what makes a good range for a moving notch (with treble intact) is not necessarily a good range for a moving treble rolloff.  A smaller cap value separates the notch and rolloff a bit more, and also keep enough treble to retain note definition.  I leave it to others to decide what their ideal spread ought to be, but the general strategy of using slightly lower values for the lowpass stages strikes me as solid and sensible.

If you do the mod, and wish to have it selectable, there are 2 ways to do it.  One is to leave the OTA side of the cap in place (at pins 5/7 or 10/12) and use a toggle to move the other end from the input to ground.  The other way is to leave the input side, and the ground side, of two sets of caps in place, and use a toggle to connect pins 5/7 or 10/12 to the free end of whichever cap you wish to use.  That way you can have all 3300pf for 4 allpass, or 3300pf for the 2 allpass, and 3000 (or 2700pf) for the lowpass.  Expect some pop, though.

Note that turning up the regen on a Ropez in phase-filter/wet-only mode gets you an interesting robust auto-wah sound, but cranking the regen on a Small Stone will kill the sound big time.  If one owns a DOD FX20, the same mod can also be done...if you can find room for it.

[DougH]

The "univibe mod" sounds intriguing. I tried that with the Phase90 when I had it on the breadboard but it did not sound very good to me. I was not using regen but it just didn't sound very "vibey" to me. Would be fun to try this on another more suitable phase circuit though.

[Mark Hammer]

Personally, I think that "Uni-Vibing" anything involves not only the spread of cap values and creation of shallow broad notches (that barely deserve to be called "notches"; they're more like dents), but the suitable location of those dips in the audio spectrum.  That, in turn, means not only getting them to start at the "right" point, but also not sweep any higher than a certain point.  It also requires complete absence of any regeneration/feedback; feedback on a Uni-Vibe sucksfarts off dead bears...seriously, it's useless, and using more of it diminishes tone.   The first part of that you can easily do in a P90, via the bias trimpot used to set the default resistance value of the FETs.  The second part is something you need a Sweep Width control to achieve, and a stock P90 does not come with that.  The third part is simply a matter of lifting the connection from feedback signal to mixing point.  If you still have a 22k, 24k or other resistance looping back from stage 4 to stage 2, then you may find that no amount of meticulousness about cap choice will deliver a pleasing Uni-Vibe sound.

[richard the sailor]

in my opinion the best one is Tonepad's phase 45 with matched transistors...........  but that's just my opinion

[Mark Hammer]

in my opinion the best one is Tonepad's phase 45 with matched transistors...........  but that's just my opinion

No need to retreat or be bashful.  Your ears hear what they hear.  Every opinion counts.

[mth5044]

Thanks for everyones replies, and thanks to mark hammer for answer mine and others questions!

Now it comes down to, for me, the phase 90 or the Ross phaser.

Time for some reflection   

[DougH]

My understanding is the Ross is somewhat similar to the Small/Bad Stone, from descriptions I've read (maybe it's the use of OTA's?) So if you have an opportunity to compare a phase 90 to a small stone in a music store, that might help you decide.

[nelson]

I'll throw my two pennys in here for Vactrol based phasing - my favourite phaser is the EHX Polyphase, it is a funky phaser.

[The French connection]

My favourite one is the phaser that comes with my Musicman (HD212-150) and it's vactrol based i think, and it can be so deep. The nice feature is that there a pull switch so it become a kind of treble EQing boost...I think i'll try to boxed him up apart someday, when i'll have more knowledge!
Anyway here's a link to schem:

http://www.gigabytesrus.com/musicman/schematic.jpg

The phaser section is at the bottom.

There's some sound sample there to: http://www.gigabytesrus.com/musicman/
but they're not really good as it should be.

Oh! I like the mxr p45 pretty much too!

Dan

[DougH]

I'll throw my two pennys in here for Vactrol based phasing - my favourite phaser is the EHX Polyphase, it is a funky phaser.

The polyphase is very cool. I wish it wasn't so big and so expensive. I like the env control function on it the most.

[Mark Hammer]

My understanding is the Ross is somewhat similar to the Small/Bad Stone, from descriptions I've read (maybe it's the use of OTA's?) So if you have an opportunity to compare a phase 90 to a small stone in a music store, that might help you decide.

The Ross is very close to the first issue Small Stone in many ways, but actually quite different than the Bad Stone.  The Bad Stone used the FETs in a hex invertor chip, and did not employ a "hypertriangular" LFO.  That doesn't necessarily make it sound bad, but it was different.

Vactrol-based phasers sound nice for a bunch of reasons:
1) Vactrols/LDRs contribute negligible noise
2) They don't crumple under hot signals so you can squeeze optimum S/N ratios out of them.
3) There is generally no need to match them.
4) They naturally adjust the LFO waveshape and sweep width as speed is increased.

[Arn C.]

Dan "The French Connection",

I wonder if the phase section of the Music Man could be pulled from the schematic and be made into a pedal. I would be interested in this.
I am not that good at figuring all that out on my own tho.  Maybe someone could help with this.

Peace!
Arn C.

[Heemis]

Arn,  I think you might be on to something... I've been looking at this schematic, and although my EE knowledge is (very) limited, I think this would be a cool project to try.  The phaser section appears to be comprised of 3 dual op amps, 1 for the LFO, and 2 for the phasing stages.  The only thing I'm not sure of is the -16v line...  Does anyone know any reason why that portion of the schematic couldn't simply be ripped out and plugged into a stompbox format?  Mark, I'm looking at you here.

[Mark Hammer]

Given that you're looking at me (Are you looking at ME?  Cuz I don't see anyone else here.  ), I'll respond.  No, there is no reason why it couldn't be taken out and used on its own.  And the same goes for the MXR Phase 100 which is essentially the same thing except with more stages.  There is nothing especially remarkable about the Music Man sub-circuit.  It is entirely textbook.  That's not a flaw.  rather, feel free to cast your gaze in a greatmany other directions (including the Morley LDR-based phaser) for precisely the same thing.  personally, I find it hard to tell from the drawing how to implement, or what portions to implement, of the LFO that is shown.

[petemoore]

Does anyone know any reason why that portion of the schematic couldn't simply be ripped out and plugged into a stompbox format?
 The reverse probably took place, a phase type effect [common to SB's] was plugged into Amp format, I believe the 2nd thing to do would be do it [starting with the PS], the 1rst would be to find where others may have left off with vactrol phase effect in SB's.
 

[The French connection]

Dan "The French Connection",

I wonder if the phase section of the Music Man could be pulled from the schematic and be made into a pedal. I would be interested in this.
I am not that good at figuring all that out on my own tho.  Maybe someone could help with this.

Peace!
Arn C.

I'll really like to see that but i'm far from being an EE. In fact, i can help on that, except if there's some protein structure to determine by FTIR spectrocopy, fluorescence quenching or structural bioinformatics. Maybe, i could help if it's DNA chips. Unless then, i'm useless. If Mr. Hammer think it would be hard to implement, i think it's futile to try.

Anyway here's a vid of a musicman phaser sound:

http://www.youtube.com/watch?v=FjRzzKzJaZw

Cheers!

Dan

[mac]

I built a P90 using tonepad pcb and ultra-matched BF245A's. It sounds excelent.
I also have a Univibe clon, a Funky Vibe, http://www.sabbadiusfte.com.ar/ , different from a P90 but a nice phaser.
But I prefer my own LDR/LED phase project,
http://www.diystompboxes.com/smfforum/index.php?topic=67167.0

mac

[DougH]

Personally, I think that "Uni-Vibing" anything involves not only the spread of cap values and creation of shallow broad notches (that barely deserve to be called "notches"; they're more like dents), but the suitable location of those dips in the audio spectrum.  That, in turn, means not only getting them to start at the "right" point, but also not sweep any higher than a certain point.  It also requires complete absence of any regeneration/feedback; feedback on a Uni-Vibe sucksfarts off dead bears...seriously, it's useless, and using more of it diminishes tone.   The first part of that you can easily do in a P90, via the bias trimpot used to set the default resistance value of the FETs.  The second part is something you need a Sweep Width control to achieve, and a stock P90 does not come with that.  The third part is simply a matter of lifting the connection from feedback signal to mixing point.  If you still have a 22k, 24k or other resistance looping back from stage 4 to stage 2, then you may find that no amount of meticulousness about cap choice will deliver a pleasing Uni-Vibe sound.

I have an easyvibe PCB so I think I'll just build that. It just seems, "easier"...

Sorry...