MRP-12 - Modified 12 Stage Ross Phaser

[chuckbuick]

So this is an evolution of my MRP-8 board which was a devolution of a more ambitious but failed 8 stage project.  The additions to this one are an extra 4 phase stages and a 2P4T rotary switch to switch between 2, 4, 8 and 12 stages of phasery goodness.  The other side of the rotary is tied to the stage indicator LED's.  Also added was a Width control a la Mark Hammer and a Mix control.  I don't know and have never corresponded with Mark Hammer.  But after working through these Ross Phaser boards I feel like I know him a little.  I certainly owe him.  If you're out there, Mark, thanks a bunch for all the info you've shared.

Now a few things that aren't so bitchin' with this build.  My implementation of the Mix control is a little flawed.  The idea was CCW would be full wet signal and CW would be full dry.  CCW is about the normal mix of wet/dry and rotating CW gradually cuts the signal but then the dry signal gets really loud and ultimately spits and sputters.  Seems like it's on the right track but it still needs to be fixed. 

The second big issue is that getting SMD LM13600/NJM13600's is tough.  Mouser got a couple hundred 2 weeks ago and I got some (back ordered the rest).  More aren't expected until late November.  BTW, yours are in the mail, Jason.  And for whatever reason 13700's do not work in these boards.  I haven't tried them in this build but they did not work in the MRP-8.  Also, I can't find my 13700's to experiment with.  Sorry, Rej, but I think they may have accidentally got tossed.  I'll check in with you soon about that.

Parts shortage and Mix issues aside I'm pretty happy with this phaser.  But enough of my words.  Here's the pics:

[jubal81]

That. Is. Gorgeous. 


Choose your stages? Mix control? Holy shit, man.


Looks like you used the Mouser 2P4T. It's pricey, but I love the feel on that. So classy.

[chuckbuick]

Thanks Jason.  That 2P4T is great.  And compact.  Works well with board-mounted pots.  Unfortunately I forgot to snap a pic of the bottom of the board with everything mounted.

[ThePastRecedes]

Oh wow, I'm kinda on a bread board binge and I was thinking of doing something like this but through hole.

Any demos?

[GrindCustoms]

Mark, that is the pinnacle of OTA phasers!

I still don't understand the problem with the LM13700, it's what i've been using in all my stuff that was asking for LM13600 with no problem, like i told you before.

Anyway, very nice build as usual but this one is particularly badass!

[jimilee]

That's truly incredible!! Btw, mark hammer is over on diysb a lot.

[TGP39]

Oh my god!  Freakin incredible. That is just a work of art.  I am floored. Bravo!

[the3secondrule]

I am in awe. that PCB is Abso-freakin-lutely beautiful!

[chuckbuick]

Thanks for the nice words, guys.

I still don't understand the problem with the LM13700, it's what i've been using in all my stuff that was asking for LM13600 with no problem, like i told you before.

Yeah, I'm perplexed.  Everything I've seen indicates they should drop right in.  My best guess is there is something different with the SMD versions of these.  But the datasheets don't show anything.  I'll keep looking for an answer, though.

Any demos?

Sorry.  I don't have any recording gear.

I am in awe. that PCB is Abso-freakin-lutely beautiful!

The way those phase stages go together made for a pretty neat layout.  They go from IC 2A>2B>3A>4A>5A>6A>3B>4B>5B>6B>7B>7A.  Once I laid those out everything else just sorta fell into place.  Routing had to get a little creative but something pickdropper told me once came in real handy here.  "Don't be afraid to use vias.  They're free."  Now, some of my best friends are vias.

[alanp]

That is so f***ing sexy.

[LaceSensor]

Just so next level awesome. That should be a commercial product once you fix the mix control.... Epic

[brejna]

Just woooow!!! Your smd work is amazing...

[the3secondrule]

Just so next level awesome. That should be a commercial product once you fix the mix control.... Epic

Yup. In a transparent enclosure.

[Thomas_H]

Thats a really great layout!

[m-Kresol]

what the others said! I really admire your spirit in designing your own circuits and the SMD parts make them even more badass. If you fix the issue (or not) I'd certainly go for one of those.
Keep them coming.