# Volkswagen Phase 45



## p_wats (Nov 11, 2009)

Hey guys,

Not sure if there's any reason to post this other than that I'm excited, but I just finished building this little guy: Volkswagen Phase 45 (with mix pot and vibe switch)! Sounds excellent!


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## bduguay (Jul 15, 2009)

Now all you need to do is attach a big gold blingy chain to that sucker and wear it around your neck yo!
Werd. hgfs
B.


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## mhammer (Nov 30, 2007)

That,s cute. Don't you need a sprig of flowers sticking up from the middle of it, though?


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## p_wats (Nov 11, 2009)

Ha! Both of those would be hilarious. 

You'd be surprised at how good this thing sounds! I've built a bunch of pedals in tins similar to this and they hold up really well too. I'm very excited to use this guy live.


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## mhammer (Nov 30, 2007)

Is that a BYOC, or Tonepad board?


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## p_wats (Nov 11, 2009)

It's a General Guitar Gadgets board. Oddly enough I had to switch the orientation of the transistors from what was printed, but that's happened to me before so I was looking for it.


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## Guest (Nov 23, 2009)

Das pedal? :smile: Cool enclosure.


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## p_wats (Nov 11, 2009)

iaresee said:


> Das pedal? :smile: Cool enclosure.


Ha! Thanks. 

Oh, and as I mentioned before, it was a GGG board, but with a few of the mods detailed here: 

http://www.lynx.bc.ca/~jc/pedalsPhase45.html

Maybe I'll post picks of some other builds if you guys would care to see them? I'm hoping to do some sound clips to demonstrate the difference between the Phase/Vibe modes of this pedal (and compare it to my BYOC Phase 90).


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## Sneaky (Feb 14, 2006)

Nice. You need to label those controls so you know what they do...

eg. Der Bigknobben, Der flikkenswitch, etc. 

:smile:


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## p_wats (Nov 11, 2009)

Sneaky said:


> Nice. You need to label those controls so you know what they do...
> 
> eg. Der Bigknobben, Der flikkenswitch, etc.
> 
> :smile:


Ha! Very nice. 

Actually, while this one is straight forward, I've gotten in a little trouble with a few of the others that I've built and not labeled...makes for interesting on-stage banter when I turn one on and it doesn't do nearly what I expected.


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## mhammer (Nov 30, 2007)

p_wats said:


> It's a General Guitar Gadgets board. Oddly enough I had to switch the orientation of the transistors from what was printed, but that's happened to me before so I was looking for it.


If I've learned anything about FETs over the years, it is that they defy all known mathematical laws and have more permutations of pinouts from 3 stinking pins than you'd predict! Throw different manufacturers into the mix, and it gets even worse.

I posted something over at the diystompbox forum recently concerning the advantages of adding a little daughterboard with two fixed allpass/phase-shift stages. So, another dual op-amp with 10k feedback and inverting input resistors, .01uf caps to the non-inverting input and a 10k-22k fixed resistor to ground instead of a JFET and all that other stuff. That fixed phase shift is added to whatever is produced by the two swept stages. The nice thing is that you can add a feedback/regen path once you hike up to 4 stages, even if 2 of them are fixed.


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## p_wats (Nov 11, 2009)

Wow! Now that is some comprehensive info. I think I got lucky with my FETs on this one, as I heard a lot of people having problems...I didn't even bother matching them and it sounds great, so I'll knock on wood. 

Adding a daughter board would be very interesting. There are also a couple guys at the BYOC forums working on a 4-stage phaser that doesn't require matched FETs or odd parts, which should be fun to try. 

I'm getting confident with the actual soldering and modding of these guys, but am still very new to the "why do they work" and more theoretical aspects.


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## shane (Oct 13, 2009)

Cool! Love VW's.


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## bduguay (Jul 15, 2009)

What you need to do now is show a gut shot of a comparable pedal next to yours and layout all the extra parts that your pedal didn't need just like the old ads for Beetles.
B.


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## p_wats (Nov 11, 2009)

bduguay said:


> What you need to do now is show a gut shot of a comparable pedal next to yours and layout all the extra parts that your pedal didn't need just like the old ads for Beetles.
> B.


Ha. Great idea! Too bad for this one I actually added parts that weren't in the original.


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## mhammer (Nov 30, 2007)

p_wats said:


> Wow! Now that is some comprehensive info. I think I got lucky with my FETs on this one, as I heard a lot of people having problems...I didn't even bother matching them and it sounds great, so I'll knock on wood.
> 
> Adding a daughter board would be very interesting. There are also a couple guys at the BYOC forums working on a 4-stage phaser that doesn't require matched FETs or odd parts, which should be fun to try.
> 
> I'm getting confident with the actual soldering and modding of these guys, but am still very new to the "why do they work" and more theoretical aspects.


The obsession with matching is one of those things that has taken on a life of its own. If they are the "right" FETs (i.e., the range of usable gate voltages is suitable and the range of potential drain-source resistances produced by that is usable) then matching is not required in order for the phaser to *work*. I myself have a very nice-sounding 4-stage P90 clone (with variable width and regeneration controls added) that also involved just throwing a quartet of unselected 2N5952s at the circuit board.

That being said, the musicality of phasers is often in how they negotiate what I like to call "the turnaround". Think of them like Olympic swimmers. It's the grace and efficiency of how the swimmer touches the side of the pool and then reverses direction that allows them to be medal-winners. All modulation effects - phasers, flangers, choruses, tremolos, Uni-Vibes, et al. - depend on the *effective* waveform/sweep to set their "character". The LFO circuit might produce a "pure" triangle or sine wave or whatever, but the manner in which it translates into actual sweep/changes is what *really* matters. Indeed, for Uni-vibes it was the lighting-up and dimmng-down qualities of the little incandescent light bulb used that proved key to the pleasing "milky" quality of the original Uni-Vibe. What the bulb did was certainly related to the waveform produced by the LFO circuit, but was not identical to it.

In the case of FETs, however, they have no lag so they correspond directly to the LFO waveform...to a point. When FETs are substantively unmatched, what can happen is that FET A and D may stop changing resistance metres from the side of the pool as C and B swim right to the end and turn around. The matching is to assure that at all points in the sweep cycle, *all* FETs are constantly changing their drain-source resistance in response to the LFO applied to their gates, and that none of them is waiting for the others to complete the sweep cycle and head back in the other direction, where they can catch up again. And that means at both extremes of sweep, the high and the low. That degree of matching, and every-FET-all-the-time sweeping provides the most pleasing sweeps.

Lets look at this from a different perspective. Many of the most prized phasers use LDRs, wither exposed to a common light source, or as part of an enclosed optoisolator package with their own LED. Can those EVER be matched? Yeah, right, and monkeys might fly out of my butt, too. So if they can never be "matched", why do they sound so good? because the LFO signal fed to them *never* pushes the LDR to as point where its resistance can not change any more, either higher or lower. So, beyond the noise and distortion issues that LDRs get past, the LDR behaves like a "perfect FET". All units move together towards each end of the sweep and all make "the turnaround" at the same time.

So, to get back on track, can you build a working phaser without going through the nuisance of matching FETs? Sure. And if you restrict the width of the sweep so that none of the FETs is ever pushed past the point where their resistance can not change any more, it will sound every bit as musical as the very best optical phaser. If you want a much wider sweep, though, such as a person might wish for very slow LFO settings, then matching the FETs will facilitate that, and may even be considered as critical to achieving "dramatic" sweeps.

Finally, the recommendation to throw on 2 more fixed stages has a hidden trick up its sleeve, and that is that you get the benefits of having more phase-shift without the responsibility to match 2 more FETs. This is a trick that is regularly used by many major manufacturers of analog phasers.


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## p_wats (Nov 11, 2009)

Wow! Thanks for all of that. The FET issue has never been explained to me at all, let alone so clearly and easy to follow! 

I compared my Phase 45 clone to my BYOC Phaser (P90 clone) and must admit I like the subtlety of this one a little more. Also, the vibe mode in this one sounds much more accurate to my ears. The P90 does have a nice milkiness to it though in comparison. 

In any case, I'm new to FETs (and electronics in general), so this is very helpful to me. I'm going to try a build using an LDR next (Clari(not)), so that should be interesting too! 

Thanks again for the information. I've got a few electronics books for musicians, but haven't really made it far yet, so every little bit helps!


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## mhammer (Nov 30, 2007)

By "vibe" mode, I'm not sure what you mean. One can obtain vibrato pitch-shift by cancelling the dry/clean signal and using only phase-shift, or one can produce a "Uni-vibe" effect by altering the capacitor values (which I gather might be what you did, given the earlier reference to JC Maillet's viva analog site).

The Uni-Vibe IS a phase-shifter. The difference between it and a "normal" phase shifter is that the phase-shift in a phaser is more focused, loeading to more pronounced (deeper) notches in very specific places. In contrast, the unequal cap values of a Uni-Vibe distribute the phase-shift in a different way, leading to much broader and shallower dips that one is hard-pressed to call "notches".

Because the dips are less obvious than the notches, and more spread out, two things tend to be true of Uni-Vibes:
1) The range of speeds is narrower for a Uni-Vibe. Ultra-slow speeds simply don't work in any audible way.
2) Regeneration/feedback does not do anything particularly useful, so you never find it on a vibe-clone.

One of the things about the broad/shallow dips in a Uni-Vibe is that if you stick it before a distortion of any kind, it results in putting different part of the guitar signal a bit higher and a bit lower, relative to the clipping threshold, resulting in a pleasing "animation" to the tone as harmonics are gently added and removed. You can do that with a phaser as well, but the Uni-Vibe does a nicer job of it.


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## p_wats (Nov 11, 2009)

I'm using the colloquial "vibe" here, as I've never owned or played a proper Univibe. I just did the mods that people refer to as "vibe mods" (ie, as you said, they alter the phasing). 

On the one hand the toggle switch changes capacitor values for the phase stages (as you described), which has a subtle effect on the sound. The mix pot also affects it interestingly by dialing in more or less of the effect, to the point that at 12 o'clock it sounds like a regular phaser, but at 4 o'clock it's more of a throbbing pitch bend-type sound with little do to no "phasing" (sounds exactly like the vibe mode on the Dunlop Rotovibe that I used to have). 

In any case, I'm very happy with it.


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## mhammer (Nov 30, 2007)

Okay, looking at JC's schematic again, the MIX control is arranged to provide a classic 50/50 blend of wet and dry in the middle position (or wherever that equivalent happens to be with the pot you are using), and phase-shift only when rotated in one direction, vs clean-only when rotated fully in the other. I shouldn't say "only" because there is still some of each signal leaking through at any setting.

On the various phasers/Uni-Vibes that I've made, I generally include a dry-lift switch and a wet-amount pot. Personally, I've always found a use for variations of less than 50% wet, but I've rarely or never found a use for anything in between 50% and 100% wet. That's why I use the arrangement I do. Either you want all the dry feasible, or not. That's not a slag at JC or the design, merely a personal preference.

When only (or mostly) wet signal is used, the subtlety of the pitch-warble produced in vibrato mode depends on how many stages are used. So, a 2-stage vibrato warbles more subtley than a 4 stage, which warbles less than a 6 or 8 stage. You can produce pitch warble by cancelling the dry signal on a chorus or flanger pedal as well. One of the reasons why I always try to include a delay-range switch/mod on a chorus.


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## ZenJenga (Nov 19, 2009)

that is so awesome! I love that. How durable is the enclosure?


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## p_wats (Nov 11, 2009)

ZenJenga said:


> that is so awesome! I love that. How durable is the enclosure?


Thanks! It's actually a lot more durable than you'd think. I've gigged (to Newfoundland and back, coincidentally) heavily with cookie tin pedals of similar thickness and they hold up well. That said, I'm not pouncing on these guys in steel-toed boots from 5 feet up, but they can definitely handle everyday use. 

I can't get over how great this one sounds too. I guess the Phase 45 is just my kind of pedal, but the mods really made it that much nicer.


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## markxander (Oct 24, 2009)

Oh man, if I had a Golf...


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