JH Tau Pipe Phaser Built As Pedal - Build Report!

[Taylor]

Totally from this site. I started here:

http://www.diystompboxes.com/smfforum/index.php?topic=60288.0

Somewhere floating around this site is a PCB transfer design. I used that, then populated it based on the photos in "a gift", and also used those photos for the wiring. It was maddening! That's why I want to get the one I built traced out into a schematic, then we can understand it a little better and do a better PCB layout. In my build, the volume was weak and it was noisy, so hopefully once it's in a schematic, we can see what I did wrong (especially the wiring must be wrong somehow - trying to figure it out based solely on those pictures was impossible and I had to make some guesses). I could maybe do a very small PCB run of professionally fabbed boards if there's interest. I know I'd like to rebuild it better, but there's no way in heck I'd ever do it the same way again. A smarter PCB layout would make it feasible.

Sorry for the derail, but these 2 boxes are kind of cousins...

[Strategy]

Sorry for the derail, but these 2 boxes are kind of cousins...

Yeah, I've heard the ?Flanger referred to as a kind of "extreme chorus" (well, I guess that's how you could describe flanging). If you think of the Tau as kind of straddling the line between phaser and flanger, I guess it is similar in being neither fish nor fowl exactly. What's really neat about the Tau is you get a sense of how really heavy chorus and vibrato was done before BBD technology.

One of the JH kits is a scanner vibrato like in Hammond organs, it's really pretty sophisticated, and I think again you can get into some really strange modulations. But again, its a big project.

- Strategy

[GP]

The pcb is currently out of print but the US modular synth hobby shop The Bridechamber (www.thebridechamber.com) still has some, I think.

failing that, you could always build one on vero 

[Taylor]

http://chud.com/articles/content_images/213/EscapeWitchMountain/Scanners.gif

[Rectangular]

Totally from this site. I started here:

http://www.diystompboxes.com/smfforum/index.php?topic=60288.0

Somewhere floating around this site is a PCB transfer design. I used that, then populated it based on the photos in "a gift", and also used those photos for the wiring. It was maddening! That's why I want to get the one I built traced out into a schematic, then we can understand it a little better and do a better PCB layout. In my build, the volume was weak and it was noisy, so hopefully once it's in a schematic, we can see what I did wrong (especially the wiring must be wrong somehow - trying to figure it out based solely on those pictures was impossible and I had to make some guesses). I could maybe do a very small PCB run of professionally fabbed boards if there's interest. I know I'd like to rebuild it better, but there's no way in heck I'd ever do it the same way again. A smarter PCB layout would make it feasible.

Sorry for the derail, but these 2 boxes are kind of cousins...

yeah, I remember that post...I still have all of that stuff sitting on my HD. I can't believe that was 3 years ago. I guess I wasn't crazy/determined enough to build one with just that info...it still felt very "iffy" to me. I've traced entire circuit boards before, and there are simply hundreds of chances for you to make a mistake. put a decimal in the wrong place even once and the whole circuit can get offset. did you ever figure out what that orange box is ? is it an audio transformer or inductor ? I remember that was a long standing mystery.

[Taylor]

I think I determined that it was an audio transformer, actually I believe it was a telephone audio transformer! I used one of the little Xicon trafos, and I assume it worked, however the mixing of the 2 channels on my build did not work properly, and I suppose this could be related to the transformer. I don't really understand transformers too well outside the standard rectification or DI box uses, so I was never sure what it does in this circuit. One guy at the other forum said very matter-of-factly that it was a voltage doubler/oscillator/rectifier doodad. The guy knows way more about EE than I, but I doubt that he's right on this one.

I wouldn't recommend delving into it until we get a better PCB layout that does away with most of the wiring, and a schematic.

[Rectangular]

I think I determined that it was an audio transformer, actually I believe it was a telephone audio transformer! I used one of the little Xicon trafos, and I assume it worked, however the mixing of the 2 channels on my build did not work properly, and I suppose this could be related to the transformer. I don't really understand transformers too well outside the standard rectification or DI box uses, so I was never sure what it does in this circuit. One guy at the other forum said very matter-of-factly that it was a voltage doubler/oscillator/rectifier doodad. The guy knows way more about EE than I, but I doubt that he's right on this one.

I wouldn't recommend delving into it until we get a better PCB layout that does away with most of the wiring, and a schematic.

agreed. I can vaguely imagine whats going on with it, I remember reading about all of its modes and getting a sense of what its actually doing. Lovetone have a habit of mystifying their effects almost to the point of obfuscation. "ying and yang" ?  also they're the only company I know that hand-sanded their ICs to prevent copying of their circuits. I dont think they understand how much us DIYers love a challenge 

I would've tried reverse engineering it if I could get a better copy of EAGLE. unfortunately the size limit of the freeware version doesn't allow for lovetone sized boards, and I dont want to learn another PCB program when I'm so comfortable with Eagle. its CAD from 1983, i wish it were just open source like gimp, inkscape and openoffice. 

[Puguglybonehead]

Wow! I hadn't realized a phase shifter could achieve sounds like this. You've done an incredible build! It seems to do the through-zero thing almost better than the Paradox TZF flanger does. (or at least differently, more smoothly?)
I wonder, is a full 20 stages really necessary to get that through-zero effect? Could it be done with say, 18? or 12?
I did like the sequenced sample. Reminds me a lot of that sweet period of Drum 'n Bass music about 12 years ago. (before things began to stagnate in that genre)
Those PCBs look like a serious pain to work on. I seriously doubt my own competence to complete one that way.
I've seen other types of phasers that look like they could be built up into 20 stages. (if the noise can be controlled)  This is intriguing as an alternative to using a BBD-based flanger for a through-zero effect. Nice!!