MXR Phase 100 finished: a little disappointing

[Bucksears]

I finished the Phase 100 last week (from GGG's layout), trying to use some mods I picked up here from Mark Hammer's recommendations (using adjustable pots for manual, regen, etc.). Anyway, I wasn't getting a decent sound out of it, so I left the variable pots for Speed and Manual mounted to the case and use individual toggle SPST switches for Depth and Regen (like the rotary switch in the commercial version). I'm getting the best possible sound (as I can imagine) out of this build. It sounds the most 'intense' with the depth control ON and toggling back and forth between the two on/off settings with the Regen. The main problem I hear is the same thing I ran into with the Ibanez Tone Lock Phaser (the first one, around '00-'01): the 'swirl' or 'spin' of the phase is more elliptical rather round; almost like a volume swell. By 'round' I mean the kind of phase I've heard in the Boss PH-1 and 2. Maybe I need to look at matched Vactrols?

- Buck

[Mark Hammer]

For a whole bunch of reasons I'm too groggy to go into, matching LDRs or Vactrols is not going to provide any measurable or audible improvement, and no reason to change them unless what you are using is simply way way off the resistance range it needs to be.

It might be helpful to post a sound sample, since it is hard to get a handle on what the problem is from your description.  The P100 has 10 phase shift stages and by all rights ought to produce a farly intense phasing effect, intense enough that modest variations in width and regeneration ought to be noticeable.  So if it isn't doing that, it sounds to me like somethng is wrong somewhere.

[Bucksears]

Thanks, Mark. I'll try to record some samples this weekend and post 'em.

- Buck

[Aharon]

Thanks for the report Bucksears,that's an elusive little critter the MXR100,not many people got it right and you seem to be in the right path.
Let us know how it goes.

[Ry]

I've got one that Bill Bergman built.  It sounds good, but is of limited usefulness.  He built it with a rotary switch rather than depth and regen pots.  Post samples and I will compare them to the one I have.

Ry

[Aharon]

Limited usefulness..........I've been tempted to build it many times(I have the dual LDRs)but it seems to be rather dull isn't it.......I think I might go for the ropez with added stages instead.
I'll follow this thread for a while tho....................

[Eb7+9]

... obviously cell matching is a big pain here ... esp. with dual cells ...

Question I have ... how does one know when the LED driver (Q1,Q2) is operating to proper "scale" ? ... with very little emitter feedback in that Darlington pair (R54 = 20 ohm) the transfer can't be very linear - I'd say it's easy for off-spec devices to throw that part of the circuit off ...

I suggest making bias on Q1/Q2 adjustable by replacing R54=20 ohm with a 100 ohm trimmer or 1k (in case real R54 value is 200ohms) - this will act to limit current through the LED's ... your LED's could be slammed "on" real hard and hardly turning off ... measure the voltage at the collector of Q1/Q2 to make sure ... or, better yet, you can measure the voltage at the emitter of Q1 with a scope or analogue voltmeter (LFO set real slow) and use ohm's law (with emitter-to-ground resistance) to estimate current throught the Darligton pair and therefore through the LED's ...

I'm guessing that's what it is ...

~JC

[Eb7+9]

...

[ukrainianrockr]

I have one question about the Phase 100. What kind of pot do u use for the on that is 2 pole 4 position?

[Bucksears]

Quick question:
Since I'm using toggle switches for the depth and regen portions that would normally be in a rotary switch, should the phasing sound be more prominent when the connections are open or closed?

Thanks,
- Buck

[swt]

maybe this is a bit ot, but after building a lot of phasers, the anderton one is the best i have, even better than any commercial units, including the excellent sounding ibanez ph99. If you are scared of bipolar supplies, it can be modified to 9volts, but you have to work on the lfo because it won't work that way. The phaser i built has a depth pot and buffer, envelope control, resonance to the point of oscillation ( really cool for madonna type of sounds, or electronic music), 6 stages, and filter mod, which is great and really simple. Let me know if you want more info on this...