# Duo Phase



## Nostradoomus (Oct 14, 2019)

I’ve had this board ready to go for months but just got off my butt (in a way) and finished it.

Used white LEDs as I was out of yellow. Sounds just fine!


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## Dali (Oct 14, 2019)

Very nice and clean build !

I just bought the PCB for that one. As a newbie I'm scared just looking at the BOM!

But since I'm a big Zappa fan that bought a SG and built a Green Ringer to get those Roxy tones, I had to get Mu-Tron.


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## Mourguitars (Oct 14, 2019)

Purdy work Nostradoomus !


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## mad5066 (Oct 14, 2019)

Very cool! Was that acid etched?


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## Barry (Oct 14, 2019)

That looks great!


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## Nostradoomus (Oct 14, 2019)

mad5066 said:


> Very cool! Was that acid etched?



Yeah, first time playing with different coloured paints over the etching.


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## Jovi Bon Kenobi (Oct 14, 2019)

Wow! It's incredible. A massive undertaking. You put a lot of "thought" into that design, didn't you?


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## Nostradoomus (Oct 14, 2019)

Tooooooo much.


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## thedwest (Oct 14, 2019)

Nostradoomus said:


> Yeah, first time playing with different coloured paints over the etching.


Did you a have a specific tutorial you learned this method from? I've seen several on YouTube but all using different methods and materials. I want to try this but haven't found a method that I'm confident in yet. Looks awesome by the way!


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## Nostradoomus (Oct 14, 2019)

Mostly this site https://diy-guitar-effects.tumblr.com/etching

This was the first time I tried using pages ripped from a glossy magazine as my transfer paper and I love the way it came out. Also the first time trying an etch on some super cheap Daier enclosures, I’ll sand it to a finer polish before I etch next time but I’m pretty happy with it!

Something that site doesn’t mention is you need to use enamel clear coat with enamel paint. If you mix acrylic and enamel you’re gonna have a bad time.


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## thedwest (Oct 14, 2019)

Nostradoomus said:


> Mostly this site https://diy-guitar-effects.tumblr.com/etching
> 
> This was the first time I tried using pages ripped from a glossy magazine as my transfer paper and I love the way it came out. Also the first time trying an etch on some super cheap Daier enclosures, I’ll sand it to a finer polish before I etch next time but I’m pretty happy with it!
> 
> Something that site doesn’t mention is you need to use enamel clear coat with enamel paint. If you mix acrylic and enamel you’re gonna have a bad time.


Awesome, thanks! I'll give this a try!


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## Dreamlands (Oct 14, 2019)

Looks great!


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## Nostradoomus (Oct 14, 2019)

Noob alert...wired it up without a switched jack hahaha. Was wondering why I wasn’t getting both sides


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## Chuck D. Bones (Oct 14, 2019)

Ha ha ha ha.  That is one awesome build! Which LDRs did you use?  What process did you use to set the trimmers?  What's with the mix of opamps?  I'm guessing you ran out of TL072s.

Just FYI to anyone who is interested in why yellow LEDs are recommended, Cadmium Sulfide LDRs are most sensitive (by a long shot) to light between 500 and 600nm.  Yellow LEDs peak out at 570nm and green around 525nm. 

I have the board and am collecting the parts.  I've got some mods in mind, of course.  One side is gonna be tuned like a Uni-Vibe, only with six stages instead of four and a switch to take out the two extra stages.  Also thinking about a Blend knob, a Throb knob à la The Abyss, a triangle-to-sine converter for one of the LFOs, throbbing LEDs, putting one or two of the trimpots on the front panel...  Definitely some experimentation is gonna happen!


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## Nostradoomus (Oct 14, 2019)

I’m 99% sure I used the Tayda KE-1270 or whatever part number it is...I used white cuz I ran out of yellow, might change it up now that I’m replenished and know it all functions well. Ran out of 072s yeah, some 4558s filled the gaps. Set the trimmers by ear at high volume, which is tedious but worthwhile...though when I change to yellow I’ll have to do it again hahaha. I’d be very interested in the univibe mod, I’ve got an unboxed Phase II board I could play around with!


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## Chuck D. Bones (Oct 14, 2019)

The Uni-Vibe mod is all about the capacitors in the phase-shift stages.
While the order should not matter, I'm sticking with the Uni-Vibe sequence:
C10 = 15nF
C9 = 220nF
C8 = 470pF
C7 = 4.7nF
and then filling in the "gaps" in the capacitor sequence:
C6 = 47nF
C11 = 1.5nF

TR2 is equivalent to the VOICE knob on the Abyss. TR1 is equivalent to the MANUAL knob on some flangers.  DEPTH, TR1 & TR2 all interact.  

White LEDs are actually 3 or 4 LEDs in one: red, green, blue and maybe yellow.  If you have a prism, then you can easily find out if the white LEDs in your Duo Phase emit any light in a yellow band.  The green emissions are probably strong enough for your pedal.  If you can get the sweep range you're after with the trimmers, then changing out the white LEDs is not necessary.  Oddly enough, my _Shaky Jimi_ Uni-Vibe clone uses red LEDs to illuminate the CdS cells. Go figure.


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## Nostradoomus (Oct 14, 2019)

I’ll AB with the phase ii board and see how they stack up. Also have a finished lovetone  doppelgänger build...I’m swimming in it


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## CanadianDave (Oct 15, 2019)

Sick job.

Clean as a whistle, and I love the graphics. 

I also love that you're using the same knobs I got with a potentiometer kit I picked up on Amazon. Those knobs have fit with a lot of designs and layouts.


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## Dreamlands (Oct 15, 2019)

Chuck D. Bones said:


> The Uni-Vibe mod is all about the capacitors in the phase-shift stages.
> While the order should not matter, I'm sticking with the Uni-Vibe sequence:



I'm still learning -- does this commutative property follow from the assumption of our allpass network being an LTI system?


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## Nostradoomus (Oct 15, 2019)

CanadianDave said:


> Sick job.
> 
> Clean as a whistle, and I love the graphics.
> 
> I also love that you're using the same knobs I got with a potentiometer kit I picked up on Amazon. Those knobs have fit with a lot of designs and layouts.



Thanks, yeah I got em off eBay haha


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## Nostradoomus (Oct 15, 2019)

Update: Added pull down resistors, changed the LEDs to yellow. Much better!


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## Chuck D. Bones (Oct 16, 2019)

Dreamlands said:


> I'm still learning -- does this commutative property follow from the assumption of our allpass network being an LTI system?



Those are some big words!  I would say "yes" because it is linear.  That is, at reasonable drive levels it's linear.  All bets are off if you overdrive a phase shifter.  It is not "time invariant," but that part doesn't matter.  We get the same phase / pitch shift for any order of the stages.  The FEEDBACK tap is between the 1st & 2nd stages; for FEEDBACK settings above zero, the order will make a difference.  Uni-Vibe doesn't use feedback.  Some derivatives, such as the EVH, do use feedback.  Some simulations and experimentation are in order.


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## Dreamlands (Oct 16, 2019)

Chuck D. Bones said:


> Those are some big words!  I would say "yes" because it is linear.  That is, at reasonable drive levels it's linear.  All bets are off if you overdrive a phase shifter.  It is not "time invariant," but that part doesn't matter.  We get the same phase / pitch shift for any order of the stages.  The FEEDBACK tap is between the 1st & 2nd stages; for FEEDBACK settings above zero, the order will make a difference.  Uni-Vibe doesn't use feedback.  Some derivatives, such as the EVH, do use feedback.  Some simulations and experimentation are in order.



Interesting! Makes sense at "reasonable" drive levels, yes -- and I want to better understand your point about feedback, so I'll dig into that, thank you.
Among other ideas for phaser related experiments, I was wondering about being able to emulate a Univibe style response by keeping the capacitor values the same, and instead independently varying the illumination of each LDR rather than having them ganged to a single LED (eg use a microcontroller to drive the LED/LDR pairs).


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