The Univibe Angle

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daveweyer
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The Univibe Angle

Post by daveweyer » Fri Nov 27, 2015 12:51 pm

I'm not the Univibe expert so I'll turn that over to JC and the others. I just started this topic to accumulate the specific Univibe discussions. You all can carry on from here, maybe cut and paste the Univibe comments that are most important.

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Xplorer
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Re: The Univibe Angle

Post by Xplorer » Fri Nov 27, 2015 7:00 pm

Very nice, if you allow me guys, i'll copy paste what we already wrote in some other threads, with the names of the authors.

if i'm missing something, please complete it.

CJH :
Uni-Vibe: yes, I got a bit gutted last week when a deal on a Castledine Supra-vibe went south and in (a probably highly emotional) response I decided I was gonna build my own clone. Jokes aside, it will have the whole power-supply on board, will follow the original layout quite closely but will be built on PPH (since I don't etch..). Some substitutions for parts (especially transistors) have been made due to availability and I have values to try both the 'early' and the 'later' circuit, however my transformer has 18V secondaries more in line with the later circuit. Have 2 sets of photocells on the way. First batch of parts got here yesterday so I'll start tinkering with it next week. If it sounds good I might go through the effort of etching a board and source correct parts down the line. In all honesty Im doing it mostly for the sake of the project, its fun! And it will keep me busy enough to not do something stupid like ordering parts for ANOTHER way too powerful amp.. I am actually pretty happy with my Sweetsound Mojo-vibe as is, Bob Sweet sure made a fine product. Maybe we should open up a Uni-Vibe thread once we get our projects rolling, so we don't go off-topic in the fuzz and modulator-threads?
.. On a side-note, JC M, I've read elsewhere that you are somewhat of a vibe-guru?

I'm underway with building a Vibe (waiting for parts atm).. Pretty much straight off the old schems but have parts to allow for a more adjustable unit. Just one Q: what photocells, or what variables in photocells do you recommend for a vintage-sounding unit?

Good luck with the chantarelles! The rain has taken the last ones up here..
Jake
Last edited by Xplorer on Fri Nov 27, 2015 7:04 pm, edited 1 time in total.

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Re: The Univibe Angle

Post by Xplorer » Fri Nov 27, 2015 7:01 pm

Xplorer :
before shinei there was the univibe made by Honey, same enclosure, smaller logo, and a few different values. some say it sounds better. that's what i'm cloning. that's likely what Jimi played. two rubber bands on the pedal.

in any case or versions, for the cells, you'll need some cells that have a very low ohms to very high ohms range, at a fast rate.
i think i'll use some VT33N2, they're said to work nicely.

other than JC take on the univibe, and his great infos and researchs on his forum, you'll find a cool thread here. This one is about doing a pure replica. you should read it entirely. there's also a potential pretty beat up univibe said to have belong to Jimi, with gut shots of it.

http://www.freestompboxes.org/viewtopic ... 8270c1816f

the voltage is a very important thing too. you can see a report of various voltage points in this thread, from an original vibe.
not necessarily better to bring more voltage apparently, but just the right voltages. about 16 - 17 volts coming from the transformer, as a start.

this said, JC will certainly have the best infos about how a univibe works, and what should should be done to tweak it perfectly. the offset bias mod seems to be a must !

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Re: The Univibe Angle

Post by Xplorer » Fri Nov 27, 2015 7:01 pm

JC Maillet :
I still have a large stash of vintage cells in my stock, if I ever have to build a bulb-based effector I'll use those // otherwise I (now) tend to go with an interface circuit that makes use of opto-isolators (either Silonex NSL-32's or NSL32-SR3's) ... I think the "bootique" cells that Smallbear have been reported to have good range (down to 1k at least), but have never used them myself ... I recommend getting a few (lot of at least 10) and selecting four closest to each other according to simple manual testing using desk light and multi-meter ... my old (original) website has all the info I think // ...

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

so you know, in my version of the Vibe I replace the preamp by a high-headroom mu-stage with volume and Presence control built-in // some feel it makes the Vibe sound and respond way better, can make it sound more open (less dark) if required ... I also increase the bias feed resistor to bring the min-speed down lower to about 1/3Hz ... all these mods have become known now, and spread by myself (and others) over time ...

guru ? // um, I think I've crossed the threshold into the realm of deities
the dink who took my work in the 90's and decided to pass it off as his own (even my early PCB layout); now, he's more the vibe-guru

:scratch:

if you're interested in cloning the vibe there's one chap you should know about (n case you don't already) who asked if he could use my work as a starting point for a definitive treatise on the Univibe // his name is Brad Burt and operates under the name Classic Amplification ... he's the author of the "Forum Vibe", a design essay that he composed w some consultation on my part (it's based on my original work) // and was meant as a definitive work on the vibe ... I would ask him about cells

FYI, I've only built a few dozen units over the years //
and, here's what I heard went down during a Roger Mayer "Vibe" showdown ...

https://soundcloud.com/eb7-9/myvibe-app ... illet-2015

:rockon: ;)

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Re: The Univibe Angle

Post by Xplorer » Fri Nov 27, 2015 7:04 pm

It's Luke :
like the idea of a separate Uni-Vibe thread.

Was fortunate to pick up an original Shin Ei Uni-Vibe unit a few weeks back, incredible tone! I would highly suggest going with an original unit even though they are pricey. Look at how much you are spending on multiple amps and other gear, I think it's worth it.

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Re: The Univibe Angle

Post by Xplorer » Fri Nov 27, 2015 7:18 pm

Now, the subject is vast ... and there's already a "univibe forum" at JC's website . So here, why not narrowing the subject as a start, with the Hendrix angle ? or what would you like to discuss ?

all i know from freestompbox, is some specific early values in the circuit, for Jimi's univibe.

by the way, this one is supposed to be one of his univibe ... no way to verify it and wow, it's pretty beat up ! but anyway, it's an early model, two rubber bands. if you want to see some gut shots of a Hendrix univibe ... that could be it :

http://www.eevblog.com/forum/chat/resto ... x-univibe/

on my univibe build, i'll start simple with a pure replica of an early one + the offset bias. then i'll play with the bulbs, cells, to have my favourite combo. then i may start to implement some cool mods from jc, and brad burt interprétations .. probably on another board. like the mu preamp.

the best univibe i've ever heard was in paris, a tech who made a vibe after ... jc's work. it really had something different from the usual wow ow ow ow wo wow oww wow wow ....
it was liquid and alive, 3d ... magic, playing itself. i've never heard anything else like it.

i attempted to build a univibe + some years ago, but for some reason i couldn't finish it and make it work, i was a bigger newbie than today. i'll probably correct it someday.

i'm missing just a few parts, then i'll start, maybe in a separate thread, a detailed univibe build story like i did for my jtm 45/100 build story, or my echoplex restoration story.

first step, thanks to freestompbox : doing a correct synthesis of the early version, which differs from the later shinei.
if i can do it in just one message that would be nice, so we won't end up in an EVH fashion, with too much infos that are impossible to synthetize for someone who starts to dive in.

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Re: The Univibe Angle

Post by C J H » Sat Nov 28, 2015 6:41 am

Sweet!!

I have mocked up a layout from schematic (with substituted parts as per my previous post). Bulbs and transformer arrived last week, the big box of parts is due wednesday but I probably won't start the build until mid-december.

Will keep you updated
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Re: The Univibe Angle

Post by Xplorer » Sat Nov 28, 2015 9:53 am

did you order a 186c28 Hammond transformer ? it delivers 28 V , and works with 230 v primary.
or 187c28 for 120v primary.

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Re: The Univibe Angle

Post by Roe » Sat Nov 28, 2015 10:21 am

personally I like the roger mayer voodoo vibe tc pedals - I have two of these (one per pedalboard)
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Re: The Univibe Angle

Post by Xplorer » Sat Nov 28, 2015 10:30 am

Roe wrote:personally I like the roger mayer voodoo vibe tc pedals - I have two of these (one per pedalboard)
is it very different from the original Voodoo vibe ? i've never tested the TC

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Re: The Univibe Angle

Post by Roe » Sat Nov 28, 2015 12:03 pm

Xplorer wrote:
Roe wrote:personally I like the roger mayer voodoo vibe tc pedals - I have two of these (one per pedalboard)
is it very different from the original Voodoo vibe ? i've never tested the TC
smaller box, same basic vibe circuit but no tremolo or chorus

http://roger-mayer.co.uk/vtc.htm
http://roger-mayer.co.uk/voodoo_vibe.htm
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Re: The Univibe Angle

Post by Eb7+9 » Sun Dec 06, 2015 1:34 pm

there are now tons of Univibe builders resources on the net ...

the main "official-DIY" collection, related to the work I've done,
is authored by Brad Burt at Classic Amplification ...
and goes by the name "Forum Vibe" :

http://www.classicamplification.net/fv/files/fv_bld.htm

my old DIY page has some anecdotal material on the circuitry, and description of some of the mods that I've experimented with over the years

for example,

things like extending the frequency range of the oscillator, extending the effectiveness of the oscillator at slow speeds, ...
a Bias Offset control, which helps accommodate varying bulb specs (a mod from my early days)
>>> things that don't change the sound quality of the signal path, but may have a strong effect on effect performance

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

I've also looked at what happens when we use a high headroom preamp ... mu-stage with Presence and Volume controls
also, being able to switch between "stock" cap values, and Reslie Tone values
>>> things that change the sound quality of the signal path a little bit, but stays in line w original design
(vintage/modern)

I've also looked/analyzed/simulated variant LFO designs ... instead of using Darlington connected BJT's, I did some with jFET's and op-amps ... I've built some with all-jFET signa paths, instead of BJT's ... I have NOT done one with vacuum tubes, despite the many requests ... I might do one with all OTA's considering my recent 6G Brownface circuit discovery ... I'also used the LFO circuit in +/- 9 volt supply situations, with zero-adjust to accomodate DC coupling // thus avoiding the losses incurred by signal caps typically included around the DEPTH control ... I've also done Vibes using threshold/ratio adjustable voltage-to-resistance converters to produce ulra wide-range Phasing, where cells go between 10Meg ohms and 100 ohms under controlled situations ... in a stock vibe they typically go about 1Meg to 1k using wide-range cells and properly darkened environment, correct bias/gain on bulb driver, etc ...

you can either build yourself a faithful replica of the original Vibes, or play with a bit of variety
I like both ... in my collection I still have a few of my very first builds, and are just as inspiring to play
maybe, even more ...

;)


---

as far as functionality goes

the pedal can be used as originally meant, ie., not direct-bypass and only with an oscillator kill switch ...
leaving the gtr signal going thru the whole circuit still

or have direct bypass, bypassing the preamp and everything

obvious to us who know, Jimi's tone was affected by the presence of the Vibe's signal path when he used one ...
so, obviously, if you're trying to copy his tone to the very last drop // yeah, go that route

these are all options to consider here ...

---

format wise,

Classic Amplification has a retro-fit board (the "Vibe Baby") that fits in a Cry Baby pedal

https://www.youtube.com/watch?v=6p5AP1xKnBk

sounding pretty good !

---

of course, the circuit is a little tricky to make happen
so, if you're going to build your own, you should know the following:

first, the quality of effect here obviously depends on choosing photocells carefully,
and the right bulb ...
the importance of the later (slow/fast bulb cool-down) may be a big deal for some, not so much to others ...
that's a personal choice

but more so even, adjusting the drive on the bulb,
and also making sure that the cells are in a light-tight environment
that part is crucial and easily overlooked ... even light creeping from the in/out jacks could affect things
that's why a light shield is used
you may also want to tape up the bottom of the PCB as well (!!)

that's often the main mistake when a vibe sounds lame, even with good cells ...
and the reason for the bias offset adjust mod

a key condition is providing proper darkness to the cells ...
since much of the action happens when the cells are in the high resistance range

so, if the bulb is biased too hot and never comes close to turning dark, you will have little effect depth

light shielding is especially important to remember in Wah-Pedal builds, as stage lights can bounce inside from the treadle opening in the pedal and go thru the underside of the PCB, depending on its material composition of course ... effectively neutralizing the cells ... just make sure to give that side of the equation its due consideration and you'll be in good shape

... of course, we also want to make sure all your cells exhibit appropriate cell-resistance range
which is dead easy to verify using a common desk lamp and ohm meter (any plain DMM will do)

grab your meter and some alligator clip wires and see what your cells measure about a 18 inches away from a 40w/60w bulb
aimed "straight-on" into the face of the cells

they should be under 1k ohms preferably, or close to that value ...
bring the cells under the desk and cup your hands around them to block out light
if you can, avoid touching the leads to the cells
you should be able to see at least 500k of resistance,
even (preferably) going off-scale when the DMM is set to 2M range

set aside four cells that exhibit similar response to this 2-state (crude) light test
do not include cells that seem to take too long to stabilize in the above test ...
cells don't have to be perfectly matched ...
but, similar to jFET's used in other Phasors, you want all cells to have similar resistive "dependence" to light
it's not so much the exact/rough "end" values, as they usually don't exist, but more the range response to light

the simple test describe here above is sufficient for this purpose
as it verifies that resistance goes very high at low light, and very low at on-light ...
otherwise the cells is considered "stuck" and useless for this task

in other words, you want wide-range cells ...
those that go below 1k (light) and well above 500k (dark)

---

which cells to buy ? ...

not sure, I have a stash of old cells that I bought years ago in a surplus shop
Steve at smallbear used to have "boutique" grade cells but I can't find that label now ...
you'd have to contact him and see which one the "vibe" guys seem to prefer

or, contact Brad Burt at Classic Amplification ...
he works on lots of original Vibes and I consider him to be the expert now, if anybody

needless to say, patience is paramount here ... the bulb bias alone is a real balancing act
and can take a few days of going back and forth before nailing the response

I hope this info helps // good luck on your build ..!!
~jcm
modern VT circuit analysis and modeling: https://viva-analog.com/product/ifmta-book-pdf/

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Re: The Univibe Angle

Post by Xplorer » Sun Dec 06, 2015 10:39 pm

you can either build yourself a faithful replica of the original Vibes, or play with a bit of variety
I like both ...

BOTH !! :wink:

thanks JC for these important tips.

i have a perfect enclosure replica for a vintage univibe ( don't ask me how, i'll can't help there ) , i'll just need to make a front plate in black anodized aluminium, with letters printed in white.
then use the vintage paxolin sheet i have ( sorry, i don't have others available anymore ) , and it'll be a very cool pure replica, using a transformer.

of course i HAVE to try a mod vibe, and also a stereo vibe. that will be other projects.

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Re: The Univibe Angle

Post by Tek465b » Mon Dec 07, 2015 10:12 am

any tip and trick on setting the bias offset and bulb driver gain using an oscilloscope?
I know a years or 2 ago i used my scope and signal generator to do it, but i really can't remember how i did and it was probably not the best way.

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Re: The Univibe Angle

Post by C J H » Mon Dec 07, 2015 3:24 pm

Thank you for that very useful info JC!

Started my build today, will definitely take a while. It's a far fetch from building a fuzz...
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