New Phaser Design - “Causality 4” – Built with you in mind!

[svstee]

When I had the depth pot wired according to the layout the pot worked backward. I switched lugs 1 and 3. Now the pot works normally, but I have that nasty gating distortion when I play hard. I didn't have it before when the depth pot worked backwards. Did I mess something up?

[svstee]

Bump. Any thoughts?

[frequencycentral]

Thy removing R8. That's the 47k resistor just above the NE5532 in the vero layout. See what happens, report back!

[doc_drop]

Rick, AKA Perfus Magnus,

I finally had a free breadboard to give this circuit a try. I am having some confusion making sense of the schematic vs your layout, though. It looks to me like the Regen Lug 3 should connect to IC1 pin 9 on the schematic, but it it shown connecting to IC1 pin 8 on the layout?

Also, I am having a hard time figuring out which caps correspond to C9 and C10 on the schematic since they are both the same value. If I read the schematic right C9 should connect to IC1 pin 8, but in the layout it goes to IC2 pin 1? Similarly, C10 connects to IC2 pin 1 on the schemo but to IC1 pin9 on the layout.

Am I missing something? (I wouldn't be surprised...)

Thanks!

Docus Dropus

[frequencycentral]

Hi Chris!

Am I missing something? (I wouldn't be surprised...)

Here's the perf layout..........the only variance from the schematic is that I've used the two OTA's of the LM13700 in the opposite order, which just made the layout easier.

[doc_drop]

Like I said, I probably just missed something.

So switching which OTA's is what accounts for the pin differences. Cool. I'll go ahead and breadboard it per the layout, since that is how I will build it if I like it as much as I think I will.

Thanks, Rick!

[frequencycentral]

Chris, as you're about to breadboard it, PM me when you've got it up and running. I've a couple of ideas I'd like you to try which could make for interesting additions.

[doc_drop]

With pleasure. Now I have to make sure I do get it up and running, though.

Uh, I don't work well under pressure, man.... But, I'll give it my best.

[svstee]

Pulled out R8. I think it actually made it worse, and it messed up the depth control, it hardly did anything and the max depth was way less.

[doc_drop]

O.K. I got this guy breadboarded. I would have had it done yesterday, but I ran into a little issue translating the OTA connections from the perf layout to the schematic then to the breadboard. A little debug this morning, and it is sounding awesome.

I changed R5 to 100K, because I like the sweep better. I am considering trying a pot here for fun. And the Regen pot works much better for me at 10K log. I get into feedback at the right at the end, so I have a wide range to play with.

Now, what were those mods you mentioned, Rick?...

[frequencycentral]

Now, what were those mods you mentioned, Rick?...

PM'ed!

[frequencycentral]

Has anyone who has built this found that the effected signal is a little less than unity? My band has just started rehearsals again after a long break, and I guess playing louder than I do at home has made me notice. I've ended up replacing R12 with a 47k resistor (was previously 100k), that's sorted it out. The other option is to leave the existing R12 in place and just add another 100k in parallel with it.

Sometimes I find that setting up a new effect for unity gain is tricky, it can be so subjective depending on the environment, the percieved volume of the effect, and how loud you are playing. I guess the solution would be to make sure the effect is slightly louder than unity and then make the resistor to ground at the output into a trimpot so folks can set it to their own version of what unity is to them.

Anyway - anyone ready for Causality 4 MkII? More knobs, more control! doc_drop has it on his breadboard right now, we've been PM'ing back and forth all week, he's been kind enough to implement and fine tune some of my ideas for an uber 5 knob version. The extra controls add adjustable up and down sawtooth in addition to triangle from the LFO, as well as an LFO width control. The original version's depth control was really a range control, defining where in the audio spectrum the phasing takes place, the new width control defines how wide ( ) the LFO sweep is. We're just finalising the mods at the moment. More to come...................

[Skruffyhound]

 

[TELEFUNKON]

Has anyone who has built this found that the effected signal is a little less than unity? My band has just started rehearsals again after a long break, and I guess playing louder than I do at home has made me notice. I've ended up replacing R12 with a 47k resistor (was previously 100k), that's sorted it out. The other option is to leave the existing R12 in place and just add another 100k in parallel with it.

Sometimes I find that setting up a new effect for unity gain is tricky, it can be so subjective depending on the environment, the percieved volume of the effect, and how loud you are playing. I guess the solution would be to make sure the effect is slightly louder than unity and then make the resistor to ground at the output into a trimpot so folks can set it to their own version of what unity is to them.

Anyway - anyone ready for Causality 4 MkII? More knobs, more control! doc_drop has it on his breadboard right now, we've been PM'ing back and forth all week, he's been kind enough to implement and fine tune some of my ideas for an uber 5 knob version. The extra controls add adjustable up and down sawtooth in addition to triangle from the LFO, as well as an LFO width control. The original version's depth control was really a range control, defining where in the audio spectrum the phasing takes place, the new width control defines how wide ( ) the LFO sweep is. We're just finalising the mods at the moment. More to come...................

A 100k pot in series with the 68k across the last opamp before the output of this schematic: http://i210.photobucket.com/albums/bb292/frequencycentral/Causality4PhaserRev10.jpg will take you anywhere volumewise.

[frequencycentral]

frequencycentral in association with doc_drop are proud to present "Causality 4" MkII:

What's new:

- Width pot added, this defines how broad an LFO sweep the OTA's see
- Shape pot added, waveform now continuously variable from upward sawtooth through triangle to downward sawtooth
- The original Depth pot has been re-named as Range, and defines where in the audio spectrum the phasing happens
- Regen pot is now 10k log for a more useful range
- Speed pot is now 470k rev log for a more useful range
- R7 reduced from 10k to 4k7 for faster maximum speed
- R12 reduced from 100k to 47k to correct the gain structure
- R5 increased from 220k to 330k
- I've switched the two OTA stages around in the schematic to match up with the perf/PCB layouts



Chris (doc_drop) has been good enough to breadboard the original circuit and implement some mods I had in mind, he's done some great work fine tuning and tweaking them to perfection, massive respect to Chris for taking this on! He's even provided some soundclips of his breadboarded circuit in action, I believe he's perf'ing it up right now. I'm pretty much stoked with how this turned out, I need to order some parts before I can get my MkII together. How cool is the internet, that two guys living over 5000 miles apart can work on something like this together???

I'm just putting the finishing touches to the MkII perf and PCB layouts, actually pretty close to the original layouts, and I'd even say that anyone with a MkI should be able to mod it to MkII spec without too much fuss. If you're not sure, just ask and I'll point you in the right direction.

The original concept for Causality was to create an 'easy build' good sounding phaser, which I think the MkI still is. MkII takes it a step further, more options and sonic variation, more knobs, more offboard wiring. The really cool thing is that the new PCB layout will be able to be used to build either a MkI or a MkII, you could even build a MkI on it and later mod it to MkII spec without to much fuss.

To round off, here some very entertaining soundclips kindly provided by doc_drop, I'll be adding my own soundclips too when I get the chance. Take it away doc!

Clean clip: http://dl.dropbox.com/u/967492/DROPed-Cause-01-31-10.mp3

Dirty clip: http://dl.dropbox.com/u/967492/DROPed-Cause-Thru-Fuzz-01-31-10.mp3

[doc_drop]

Yep, I have this bad boy working on perf now. I am no Frequency Central when it comes to the neatness of my perf builds, so it took a fair amount of debugging to get the kinks ironed out, but the schematic is now verified, and the perf build is really close to the layout FC already posted.

If you want to build a phaser, I highly recommend this one. It has a wide range of sounds. As I said to FC, it is somewhere in between the ROG TriVibe I recently built and FC's Phase Revolution. But it has a certain "je ne sais quoi" that makes this a sweet little phazing, chorusing, vibing, outer spacing circuit!

And not having to match trannies is a huge benefit. (No, don't put quote that in your signature, you pervs!)

doc_drop

[bobp1339]

I will be revising my causality4 to an mkII!!  I love the original, looking forward to play with the MKII!!!

Thanks Rick and Chris!!!

[Renegadrian]

And I will revising my signature!!! 

[doc_drop]

Here are some pics of the development process. My breadboard has never been so full, and so useful!

Breadboarding:




On Perf:


P.S. I knew somebody would enjoy my humor, Renegadrian!

[StereoKills]

Looks awesome! MKI was already on my to do list, looks like I need to look into ordering more knobs.