Phase 100 vs. Phase 180

[Skullnick]

So I been wanting to build one of this for a long time. What is the difference between the two and which one is better?

[petemoore]

So I been wanting to build one of this for a long time. What is the difference between the two and which one is better?
  The one thing I'm actually certain about is that they're all good, all phase, all sound the way they sound, more phase stages = more depth [up to a point...].
  If you want to order a Kit,
or PCB, from GGG, the PH100:
  http://generalguitargadgets.com/index.php?option=com_virtuemart&page=shop.browse&category_id=7&Itemid=45&TreeId=16&phpMyAdmin=4a28f86a515b7883e7bc35a68d4e7b6d
  And you can see how many phase stages etc. by looking at it.
  IIRC the 180 has simply added phase stages, so by bypassing some of them you could get phase 100...check my memory and count 'em though...and how alike the LFO's are...
  Phase 90's working great here, depth mod and all.

[mdh]

One major difference between the Phase 180 (which is R.G.'s extrapolation of the MXR Phase 90 to eight stages) and the Phase 100 is that the Phase 180 uses FETs as the resistive control elements for sweeping the phase stages, whereas the Phase 100 uses LED/LDR optocouplers.  Also (if I'm reading the schematic correctly) the Phase 100 has 10 total phase stages, 6 of which are swept, and the other 4 fixed.  I'm not sure what effect this has on the sound.  Practical issues are that for the Phase 180 you would have to get 8 closely matched FETs, which probably means that you should buy at least 50; for the Phase 100, you have to get the somewhat rare dual optocouplers.  The only place I know of that has them is Small Bear Electronics.  One other practical issue is that there is a layout available for the Phase 100, but I know of no publically available layout for the Phase 180.

I've played around with something like the Phase 180 on the breadboard, and I have to admit that I felt like I was hearing diminishing returns after 6 stages.  I'm not sure that I would characterize the effect of added stages as "more depth," I think that's more a function of the LFO and the ability of each stage to respond to the LFO.  I don't have any direct experience with it, but I suspect you would be more satisfied with the Phase 100.  You should also be aware that there are a few phasers on Tonepad: Phase 45, Phase 90 and the Ross Phaser.  In my quest for the ultimate broadly sweeping clean phase tone, the Ross Phaser has been recommended to me more than once.  I've also built the Phase 45 and Phase 90, and they're very nice too.

[Skullnick]

But isn't the Phase 100 suppose to be an advanced version of the Phase 90.

[mdh]

But isn't the Phase 100 suppose to be an advanced version of the Phase 90.

My understanding is that it's supposed to be a more advanced phaser than the Phase 90.  Still, the differences I described are correct, just look at the schematics.

[Mark Hammer]

But isn't the Phase 100 suppose to be an advanced version of the Phase 90.

"Advanced" can take many forms.  The Phase 100 has the following differences with the Phase 90:

a) Use of photocells instead of FETs (lower noise and better signal handling and assurance of consistent sweep)
b) Two sweep width settings
c) Two resonance settings
d) More stages of phase shift (= more notches)

I'm not sure if anyone here has looked at the shape of the LFO output so I don't know if there is any difference in the "feel" of the sweep.

About the extra stages.....

Notches are produced when there is at least 180 degrees of phase shift at frequency F, adding up all the phase shift across stages.  Whether the stage is fixed or swept, it can still provide phase shift.  Think of it like a tug-of-war team.  The person at the very end of the rope still provides "pull", even if they aren't trying, as long as they have some weight, hold onto the rope and simply lean backwards.  The fixed stages do the same thing here.

Each phase shift stage, whether swept or not, will contribute varying degrees of phase shift, with phase shift increasing up to some maximum and then plateauing at 90 degrees per stage.  If you look at the "bottom" of each phase shift stage, you'll see a cap going to the noninverting (+) pin of an op-amp and some type of resistance to ground (FET, LDR, resistor).  That is essentially a highpass filter, and like any highpass filter of that form, there is a 6db/octave rolloff below whatever the corner frequency is, and flat response from just above the corner frequency to whatever the system's upper limit is.  That means you could have only 10 degrees of phase shift per stage for some frequencies at a given point in the sweep.  If you had 18 stages, though, you'd still produce a notch at that frequency.

So, the extra unswept stages in the Phase 100 add more phase shift above some point.  As it happens, use of a .01uf cap and 22k resistor to ground in each stage mean that 90 degrees-per-stage is not added until around 720hz or so, although lesser amounts of phase shift are added to whatever the swept stages are providing below that frequency too, making it easier to generate notches at those lower points.

[Mojah63]

I have the ross, mxr 90, mxr100, used to have a mxr45...
Now the old which one is better.. None really.... They sound different.
The ross sounds lighter airy and as memory recalls like the 45
my 90 sounds thicker + sweeps heavier
my 100 does not sound like the 90 at all. The sound is
heavier than the Ross lighter than the 90. I personally
love my 80's block mxr 100. I use it with the sweep all the way
down to thicken up a strat a bit in place of chorus.

My observations are purely subjective...

So I guess you'd have to build them\try them yourself.
P

[Mark Hammer]

The "sound" of a given phaser can often be  changed considerably by shifting the range of sweep (i.e., start/stop points in the sweep) over so that it sits in a different part of the frequency spectrum.

[DougH]

The Phase 100 has the following differences with the Phase 90:

a) Use of photocells instead of FETs (lower noise and better signal handling and assurance of consistent sweep)
b) Two sweep width settings
c) Two resonance settings
d) More stages of phase shift (= more notches)

I'm not sure if anyone here has looked at the shape of the LFO output so I don't know if there is any difference in the "feel" of the sweep.

I can vouch that the Phase 100 has a "wobbly" sounding LFO sweep - an "ooooWOW-ooooWOW-ooooWOW" compared to the "WOW-WOW-WOW" of the Phase 90. I have a breadboarded Phase 90 sitting right next to my new Phase 100 on my bench right now.

The Phase 100 is my absolute favorite of the old-school 70's analog phasers but I think they are both great phasers that compliment each other real well. They sound different and each do different things well. The Phase 100 probably has the most "vibey" sound of any phaser like this I've ever heard. Put it between your guitar and a distortion box and it really comes to life in this respect. The doubling, almost-flanging, almost chorus sounds it produces when driving a distortion are amazing- Robin Trower's univibe sound on steroids. It does beautiful shimmery clean sounds as well. The Phase 90 sounds great too- esp without the feedback, and I can't wait to build it either.

Sorry to gush so much and revive such an old thread. I wanted a Phase 100 30 yrs ago and never got around to it until this week. () I fell out of love with phasers for a long time, but am now very much back in love. Used in particular ways they can sound absolutely amazing...

[Mark Hammer]

"oooo-WOW" is not exactly a helluva lot to go on, but your description suggests something akin to a hypertriangular sweep - sluggish at the low end but with a faster turnaround at the top part of the sweep.  Given the substantially more complex sweep generator in the 100, compared to the single op-amp LFO in the P90, that makes sense.

The right phaser in front of the right distortion IS magical, I have to concur.  I've said it before, but what people tend to forget is that the notches produced by a phaser have the same net effect as turning down the gain on the distortion, or better, turning down the guitar volume, in a cyclical fashion.  Where a phaser after a distortion operates like subtractive synthesis - filtering harmonic content selectively from a pre-existing harmonic-rich signal - a phaser before a distortion operates like additive synthesis - generating additional harmonic content to a basic signal in a manner that can best be described as "animating".

I urge those of you who are accustomed to sticking your phaser later in the signal path, where you put most of your modulation effects, to try putting it before your distortion pedal/s for a change.  If you haven't done so before, you may just like it!

[DougH]

Yes, only so much I can do with a text description. But it's not even, but more "wobbly".