UVICS - Univibe In a Crybaby Shell

[R.G.]

Finally got back to this. New name, same circuit. Many thanks to the guys who helped wring out the first round of mistakes!  

Just finished the docos, so there could still be a bug lurking in there, but it's been built, and works.

DOH! Gotta put in the link: http://www.geofex.com

[theundeadelvis]

Awesome RG! Thanks!

[Mich P]

Brilliant,
Thanks R.G.
Mich P.

[petemoore]

  It is surely cool, vibe w/speed ?
    Link brings blank page here.

[Mike Burgundy]

I can only find the 2010 updates. Am I still asleep?

[R.G.]

It's #1 in the "New At GEO" list on the main page; 7/2/11.

Here's the direct link: http://geofex.com/FX_images/UVICS-Proj-file.pdf

I tried to make it work most easily with the most common Crybaby, the kind where the wiring plugs into pins on the PCB. For others of the various Crybaby models, you may have to manually solder wires in.

I have a PCB that puts a rectifier diode and filter caps back in the heel of the pedal, but DC-output wall warts are pretty common in the 18-24V range. It's probably easiest to use one of those. Doesn't need regulation, there's a 15V regulator on the UVICS board.

There is one wart to the way I did the single pot to dual pot mod. LDRs unavoidably do "dark adaptation", which means that when they're in the dark, the go to some resistance value, then over a few seconds get slightly higher resistance. So when you rock the pedal back, it goes to slow; then over a few seconds, it gets a bit slower. It's just the way it is.

All the normal mods to the univibe apply. Changing the values of the input resistors gives you high impedance, over 1M. I made the compensation cap be the collector-to-base version I found, but there's a hole there for the stock cap-to-ground connection of the original.

There is a trimmer for setting the sensitivity of the LED/LDR, but this is also where R51 goes; you can use a pot, measure it, and solder in a fixed resistor.  I also put in trimmers for stereo mix, and both base and emitter bias settings on the lamp driver.

The real restriction is part size. Use the right parts. I -er- mentioned that a few times in the instructions. The correct parts are available.

[RedHouse]

Layout looks good.

[Mike Burgundy]

Thanks for the direct link - even a flushed cache leaves me with 3/6/11 as latest post. Weird.
Looking great! Even has the obligatory spelling mistake for good measure ;P (note 12 - soldered over the top to hole it on)
Very, very nice artwork.

[R.G.]

Thanks for the direct link - even a flushed cache leaves me with 3/6/11 as latest post. Weird.
Looking great! Even has the obligatory spelling mistake for good measure ;P (note 12 - soldered over the top to hole it on)
Very, very nice artwork.

Thanks. It's at least mildly embarrassing that English is my native language - and I still can't spell correctly, or consistently. 

I'll go rework that. Thanks for the help proofreading.

I just finished adding a power rectifier/filter section to the end of the board for AC inputs if needed. May take a bit to get that on line.

[Mike Burgundy]

I know people who spell immaculately but wouldn't know a soldering iron if they picked it up by the business end - I'm sure we all prefer RG in his current state
*edit* - caching problem (which I assume it was) now solved, I see the new item too.

[kvandekrol]

Amazing! Can't wait to build it.

A couple of possible errors in the schematic that I wanted to ask about: C12 and C15. In the Neovibe, C12 is 470pF and C15 is .0047uF; in the UVICS, C12 is 0.47uF and C15 is 470pF. Is the UVICS schematic incorrect?

[R.G.]

A couple of possible errors in the schematic that I wanted to ask about: C12 and C15. In the Neovibe, C12 is 470pF and C15 is .0047uF; in the UVICS, C12 is 0.47uF and C15 is 470pF. Is the UVICS schematic incorrect?

Probably I ought to say that the UVICS schemo is correct for the UVICS -    - but no, I typed the values into the schemo incorrectly. Good catch, and thanks.

That's what I get for both postponing this for over a year because of the moaning, and for doing the docos quickly when I got some time to get back to it.

Thanks for the note. I'll update the schemo.

It's worth noting that you can experiment with the values of C5, C9, C12, and C15. I don't know what the original idea was, but I believe that the cap values were chosen for making the vibrato better by distributing the phase shift over the range of audio frequencies. Changing them has a subtle but audible effect. Feel free to tinker with them. It won't affect the DC conditions, and you may find a hybrid you like better.

[R.G.]

Updated.

[Keppy]

I saw this on GEO the day it went up. Now I have to figure out what to do with my Crybaby shell... this or the volume & boost I designed. Dunno when I'll find ANOTHER cheap/dead wah on Craigslist... and I need an expression pedal for my wife's ring modulator, too...

I guess I have a problem with rocker pedals. Between this and the Phase II, you're really feeding my addictive behavior, R.G.   

[R.G.]

I guess I have a problem with rocker pedals. Between this and the Phase II, you're really feeding my addictive behavior, R.G.   

Just remember - anything worth doing is worth over-doing. 

[RedHouse]

I might as well post my own findings about the use of MPS-A13's thoughout the phase stages.

When I did tried of MPS-A13's for the Forum-Vibe back in 2005 I too replaced allthe transistors in the phase stages with the true darlington MPS-A13 but then during listening tests quickly realized they changed the "throb" or "lope" (for lack of better verbiage) of the vibe too much for me, so much that the bias offset mod was unable to pull it back home to what I consider the proper "vintage" univibe sound. That's when I dumped the notion of using them on all the stages and just recommended replacing Q10 with an MPS-A13. Which reminds me by the way, even sub'ing an MPS-A13 in the Q10 position can be too much with the wrong LDR's I think.

When using true darlingtons (MPS-A13's) I think the "throb/lope" changes away from the vintage sweep kind of thing (eeeoooaaawwwaaaoooww) into more of a toggled sweep (yawingyawingyawing) with not as much dwell time in the area between each end of the sweep, which is not to say there isn't plenty of coolness there, it's just not the vintage tone to me.

I was going to recommend you might edit "Notes-2" in your PDF to reflect this.

Just to elaborate a little on my own findings, to accomidate the testing I built a "test fixture" with 2 vibes on it, one was bone-stock vintage build the other had sockets for everything change'able so immediate comparisons and part substitutions could be made w/o buiding a new vibe or soldering/desoldering parts. I did this for personal insight on proving/disproving the value of any of the mods anyone suggests on a vibe (mostly for my own benefit) but I do like to share my findings when appropriate.

Here is a pic of the socket-side of the board:  http://classicamplification.net/forumvibe/pix/vibe_with_sockets.gif and with this test tool I am always able to try/test every permutation in the vibe curcuit, transistors, caps, LDR's, Bulbs etc. An easy, fast, and ultimately decisive way to do vibe tests so it was well worth my time buillding the test fixture.

Again just to reiterate (and be clear) this info is offered in the sprit of goodwill-forum-community. I post this simply as sharing the knowlege .  

[R.G.]

It's actually quite an old project for me.

The idea about putting the univibe circuit into a crybaby rocker came up a very long time ago. In fact I can get out some of my first postings where I note that the original Neovibe board fits into a crybaby rocker, if you cut off the mounting posts. I'll have to do the research but I think that was about 2000, maybe before. I did the in-the-Crybaby-board, didn't release it because most people seemed to be hot to build them into their own square boxes; not as much interest in the crybaby-specific one. I did finally get around to releasing the crybaby specific one in 2009 when I got back to it. I don't release everything I do, either immediately or sometimes ever.

When using true darlingtons (MPS-A13's) I think the "throb/lope" changes away from the vintage sweep kind of thing (eeeoooaaawwwaaaoooww) into more of a toggled sweep (yawingyawingyawing) with not as much dwell time in the area between each end of the sweep, which is not to say there isn't plenty of coolness there, it's just not the vintage tone to me.

It does vary. I've done the listening to pretty much every variation you can think of on the univibe circuit - and the RT-18, it's predecessor with tremolo - since I started messing with it back in the 90s.

It's funny - every time I do something different to a vintage circuit, and especially the univibe, I get chewed on by "experts" who decide that any change from the holy original circuit sounds bad, and is just somehow *wrong*. It's happened since I released the first Neovibe back before there was a world wide web to surf on.

Back then, a couple of guys carped about the non-original sound of the voltage regulator. One guy in particular harped on it over and over as "not original sounding". A lot of people wound up laughing at him, but that's beside the point. One guy even griped that the different layout of the parts didn't match the original layout, and the sound was all wrong. Of course, both these guys were trying to make money selling clones of the original and didn't take kindly to my just giving away a layout that enabled people to do their own, so I think they had a different agenda.

In general, changing anything about anything will be called out as changing it. Sometimes some people can even hear a change. But point taken. I'll post a version with discrete transistors for those people who think they can hear a difference. Layouts are pretty simple for me, but yeah - somebody somewhere is sure to first carp about it not sounding original, then to go off and cook up their own business making mods and selling them as super-hyper-mondo better somehow. It's as amusing as it is predictable.

I did the listening test on true darlingtons a while back too, and had some people who are very picky about tone listen. They could hear differences in tone... but their "hit" on recognizing the original circuit was about the same percentage as blind guessing. Maybe it makes them feel better.

Just to elaborate a little on my own findings, to accomidate the testing I built a "test fixture" with 2 vibes on it, one was bone-stock vintage build the other had sockets for everything change'able so immediate comparisons and part substitutions could be made w/o buiding a new vibe or soldering/desoldering parts. I did this for personal insight on proving/disproving the value of any of the mods anyone suggests on a vibe (mostly for my own benefit) but I do like to share my findings when appropriate.

I do too. Sharing findings is good. I find that changing anything changes something. I also find that changing *human listeners* has an even greater effect, and even more, I can suggest that something sounds different, and it will. The personality of the listener has a huge effect. Some people are suggestible, and the one I suggest sounds good will sound good to them; others are counter suggestible, and what I suggest will sound good will sound worse to them; I guess they show me, huh?

Again just to reiterate (and be clear) this info is offered in the sprit of goodwill-forum-community. I post this simply as sharing the knowlege.

Thanks, Brad. Just to reiterate to you, my response is given in the same spirit yours was offered. I feel the spirit of your posts and reciprocate it.

I had some experience in my last life with the hyper-adrenaline sales guys in the mainframe computer market, where making a fortune for the salesman hinged on him getting the order. When your competitor had something new but you didn't, you could FUD the customer. That acronym stands for Fear, Uncertainty, and Doubt.  The idea was to drop hints quietly and you know, off-the-record-I-shouldn't-even-be-telling-you-this, that Something Bigger and Better was coming, and there were ugly little rumors the salesman had heard about customers not being really happy with buying the competitor. You know, just wanting to keep you from making a big mistake, cause you're my favorite buyer. FUD was widely disparaged by the sales people, who called each other down on it all the time. Ugly practice.

I guess my mind is wandering - I don't know why that came up.

[RedHouse]

Wow, still sounds like issues to work through, you're definately not feeling the love.

Again, no negativity intended when I say (as before) nice new layout, good work, well done.

[R.G.]

Wow, still sounds like issues to work through, you're definately not feeling the love.

Brad, I asked you politely, and privately by PM, not to go through this again. If you want to play "who's got issues?", I can do that as well as you can.

The snide "no negativity intended" and innuendo attacks are nothing new, and not all that clever, frankly. I've been insulted by experts, in both obvious and subtle ways, and so this isn't particularly novel.

I'm going to ask again, politely, for you to stop it.

[RedHouse]

I'm being very polite so c'mon let it go.