Dunlop - UV1-SC UniVibe Stereo Chorus  [schematic]

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Dunlop - UV1-SC UniVibe Stereo Chorus

Postby Tonetweaker » 06 Feb 2011, 03:57

Hey all...

loubou mentioned wanting to get a peek at the Dunlop UniVibe Stereo Chorus, so here it is...

SAM_0140a.jpg


SAM_0142a.jpg


SAM_0143a.jpg


SAM_0144a.jpg


SAM_0146a.jpg


SAM_0147a.jpg


SAM_0148a.jpg
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Re: Dunlop UniVibe Stereo Chorus UV1SC (gutshots)

Postby Tonetweaker » 06 Feb 2011, 04:27

More...

SAM_0149a.jpg


SAM_0150a.jpg


SAM_0151a.jpg


SAM_0153a.jpg


SAM_0154a.jpg


SAM_0157a.jpg


I tried to take some close in shots, since the board is pretty tightly spaced. Please excuse the "jittery hand" quality though. :P

The board is pretty tightly held in by the pots, switch and jacks... The jacks had recessed threads, so that once you remove the retaining nut, there's no overlap with the chassis to worry about. As with most modern Dunlop products, they did a nice job of putting the unit together. I wouldn't be too nervous if this one got knocked onto the floor by mistake.

Of all my chorus/vibrato units, this one is my favorite. Good range and control.

As always, if more info or pics are needed, let me know. I'll keep it apart for a day or two to see if anyone has any requests or interest in reversing it.


Cheers...
Steve
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Re: Dunlop UniVibe Stereo Chorus UV1SC (gutshots)

Postby Tonetweaker » 06 Feb 2011, 04:32

Sorry about the stray shot at the end. It got separated from the herd somehow, and there's no edit function available in this section. :lol:
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Re: Dunlop UniVibe Stereo Chorus UV1SC (gutshots)

Postby lolbou » 06 Feb 2011, 11:16

No bulb/LDRs in this one. Opamp phase stages. I guess it's all around the TL074, on the right of the switch...
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Re: Dunlop UniVibe Stereo Chorus UV1SC (gutshots)

Postby blackbunny » 06 Feb 2011, 13:21

lolbou wrote:No bulb/LDRs in this one. Opamp phase stages. I guess it's all around the TL074, on the right of the switch...


By golly, I think you're right....no lamps or LDR's. Completely different design to our "vintage" UV-1's.

How does it make that nice lush stereo chorus that Tonetweaker likes so much, using op amps?
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Re: Dunlop UniVibe Stereo Chorus UV1SC (gutshots)

Postby lolbou » 06 Feb 2011, 14:10

blackbunny wrote:using op amps?
That's what I supposed mentionning the TL074... Hey Tonetweaker, can you tell us what are the transistors around that 074 chip? Are these FETs?
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Re: Dunlop UniVibe Stereo Chorus UV1SC (gutshots)

Postby Tonetweaker » 06 Feb 2011, 20:00

blackbunny wrote:
lolbou wrote:No bulb/LDRs in this one. Opamp phase stages. I guess it's all around the TL074, on the right of the switch...


By golly, I think you're right....no lamps or LDR's. Completely different design to our "vintage" UV-1's.

How does it make that nice lush stereo chorus that Tonetweaker likes so much, using op amps?


In fairness, you guys may not like this thing nearly as much as I do... My experience is fairly limited when it comes to effects. I don't have a lot of knowledge on what a lot of vintage circuits sound like, and when I hear a lot of my favorite recordings, I don't always know which "magic boxes" were responsible for that sound.

That's part of the reason I'm here, BB... To learn from the guys that really know about this stuff. :mrgreen:

That said, I really do like the sound of this thing. I use it all the time.

lolbou wrote:
blackbunny wrote:using op amps?
That's what I supposed mentionning the TL074... Hey Tonetweaker, can you tell us what are the transistors around that 074 chip? Are these FETs?


Yep. JFETs. All four are Fairchild 2N5952.

Incidentally, anyone know what the little codes above the ID are for? Each one has a small code like "B419" or "D346"... Doesn't seem necessary for the ID. Perhaps a lot number or some kind of date code? All 4 are 2N5952, but each one has a different code above.


Cheers...
Steve
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Re: Dunlop UniVibe Stereo Chorus UV1SC (gutshots)

Postby lolbou » 06 Feb 2011, 20:10

Tonetweaker wrote:Yep. JFETs. All four are Fairchild 2N5952.
Expect something looking like the Phase 90 4-stage circuitry... :wink:
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Re: Dunlop UniVibe Stereo Chorus UV1SC (gutshots)

Postby Tonetweaker » 06 Feb 2011, 20:59

lolbou wrote:
Tonetweaker wrote:Yep. JFETs. All four are Fairchild 2N5952.
Expect something looking like the Phase 90 4-stage circuitry... :wink:


That would certainly explain the swirly quality... :lol:

I'm nowhere near familiar enough with these circuits to recognize close parallels to other effects. I'll have to dig up a schematic of the Phase 90 to give it a closer look. I'm sure I have it here somewhere. :thumbsup
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Re: Dunlop UniVibe Stereo Chorus UV1SC (gutshots)

Postby Dirk_Hendrik » 06 Feb 2011, 21:50

As this "univibe" seems to be a standard 4 stage phase with FET's it would be interesting to see in which extend it is following the concept of a phase90 with altered coupling cap values. Which is more or less what people tend to call "univibing" when they rape a phase90 with altered caps and call it a "univibe".
Sorry. Plain out of planes.

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Re: Dunlop UniVibe Stereo Chorus UV1SC (gutshots)

Postby lolbou » 06 Feb 2011, 21:57

Any idea why there are two 4016 in it? Is it just for stereo purposes? :scratch:
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Re: Dunlop UniVibe Stereo Chorus UV1SC (gutshots)

Postby Tonetweaker » 07 Feb 2011, 00:25

Dirk_Hendrik wrote:As this "univibe" seems to be a standard 4 stage phase with FET's it would be interesting to see in which extend it is following the concept of a phase90 with altered coupling cap values. Which is more or less what people tend to call "univibing" when they rape a phase90 with altered caps and call it a "univibe".


Could very well be, Dirk. I'm certainly no expert on either effect. It could be nothing more than a stereo Phase 90... but it sure sounds nice. :P

This thing definitely provides a pretty nice range of sounds. More than my Phase 90 does, I'd say... not that there's anything wrong with that pedal either. I love the sound of a good swirly phase effect.

Somebody cue the psychedelic music... :lol:

lolbou wrote:Any idea why there are two 4016 in it? Is it just for stereo purposes? :scratch:


Good question. I was curious as well... but as I mentioned, I'm not much on just looking at the board and understanding the circuit configuration. I wish I was, actually. It would keep me out of trouble sometimes... :lol:

The outputs are labeled "Left/Chorus" and "Right/Vibrato" if that provides any clue...

The output jacks are right next to each other... The single one on the other side near the AC input is the input jack. The jack closer to the pot is the left channel. The one closer to the switch is the right.
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Re: Dunlop UniVibe Stereo Chorus UV1SC (gutshots)

Postby Mafra » 05 Dec 2011, 16:08

Does anybody have the schematics of this pedal (UV1SC)?
Mine has a problem when I turn it off: a noticeable shriek that modulates with the "vibe". Works perfectly when turned on.
Any help appreciated.

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Dunlop - UV-1SC UniVibe Stereo Chrorus - revision B  [schematic]

Postby apollomusicservice » 25 Jun 2012, 11:04

After several unsuccessful attempts to get the schematic for Uni Vibe stereo chorus,
I decided to draw my version.
This schematic is not official and I apologize if there is some mistake somewhere,
but it helped me to fix my Uni Vibe.
I hope it will be useful
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Last edited by modman on 28 May 2015, 09:08, edited 2 times in total.
Reason: Topic moved and renamed ;-)

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Re: Dunlop- UniVibe Stereo Chrorus - UV-1SC (PCB RevB)

Postby apollomusicservice » 27 Jun 2012, 17:27

This is a little corrected drawings with some measuring points to facilitate inspection of individual parts.
The test signal is 8oo Hz and the pedal is activated.
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Re: Dunlop- UniVibe Stereo Chrorus - UV-1SC (PCB RevB)

Postby apollomusicservice » 13 Jul 2012, 17:56

...and components placement
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Re: Dunlop - UV1-SC UniVibe Stereo Chorus

Postby rna » 17 May 2019, 12:00

Hi, very useful thread this. I have one of these on the bench for repair. The owner said it was zapped with over voltage at a live gig from a dogy generator.
After finding the TLC2264AIN had blown as well as the tl074 I still have to find out why the bypass is not working.

This looks to be an older version and on this board R9 is a 1ohm resistor. Maybe they just replaced it with a trace.
This one has a resistor mod (300K) pin7 of the Hex-Channel Buffer to the RR54 / R49 junction.

Great sounding pedal though. I can't wait to hear it with 2 amps connected.
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Re: Dunlop - UV1-SC UniVibe Stereo Chorus

Postby mr coffee » 13 Jun 2019, 23:22

Has anybody checked to see what the control signal going to R4, R12, R19, and R40 looks like?

I'm guessing it is converted into a low frequency sweep voltage and not used as PWM to vary the JFETs apparent value, but I sure would like to know what the waveshape looks like (i.e., a low frequency sine wave, a warped low frequency sine, etc.).

Anyone every put a scope on it to see?

Thanks very much to apollomusic for posting all this. Really an interesting take on a very old effect. :applause:

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Re: Dunlop - UV1-SC UniVibe Stereo Chorus

Postby rna » 17 Jun 2019, 00:33

Yeah it makes a tiny control signal. This pic is with the fastest speed setting and full intensity.
univibe intensity control.png
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Re: Dunlop - UV1-SC UniVibe Stereo Chorus

Postby rna » 17 Jun 2019, 00:56

Here is a demo of a vocal through the pedal and a live performance on the controls.
The first loop is with out the chorus and then again with.

https://www.dropbox.com/s/9z994kqwjui87 ... L.mp3?dl=0

(is it possible to upload .mp3's to this site?)

univibe xamp2.jpg
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