Any Univibe players out there?

gnugear · Post by **gnugear** » Thu Nov 18, 2004 1:23 am

I'm jonesing for a Sweet Sound Mojo Vibe. I just love that drunk, wattery Hendrix sound that you hear on "Machine Gun". I've tried a BOSS COSM modeling pedal and also a Line6, but nothing seems to really touch the sounds of a stand alone pedal.

What do you guys use?

flemingmras · Post by **flemingmras** » Thu Nov 18, 2004 1:58 am

I use an MXR Phase 90 so I can do You Really Got Me by Van Halen and turn the speed knob all the way down and get Eddie's lead tone for that. The Univibe is a 4 stage phase shifter just like the Phase 90, however the way they shift is WAY different. I'm going into "******" mode on this one.

Basically what a phase shifter does is your guitar signal gets split into 2 signals. Both of them are buffered, but one gets left dry and sent straight to the output stage. The other signal goes through 4 phase stages. Each stage is identical to the first and when you string shift stages end to end like they do in phase shifters, choruses, flangers, etc, they call this a "bucket brigade". Matter of fact choruses and flangers use a chip called a "bucket brigade device", which consists of several of these delay stages end to end(way more than a standard 4 stage phase shifter). The most popular of these bucket brigade devices is the SAD1024.

What happens is that the signal that goes through the delay stages gets flipped 180 degrees out of phase with the dry signal. However, since each frequency has a different wavelength(the higher the frequency the shorter the wavelength), only 1 frequency at a time can be exactly 180 degrees out of phase with the frequency of the dry signal. This signal gets mixed with the dry signal through a couple of mixer resistors in the pedal(similar to the 470K mixer resistors in a Super Lead) and then fed into the input of a final preamp stage before it hits the output jack. Whichever frequency is exactly 180 degrees out of phase with the dry signal will be the frequency that gets completely cancelled out.

Then there's a LFO circuit(Low Frequency Oscillator) in the pedal that generates a low frequency signal. The frequency of the signal is controlled by the speed knob. In a Phase 90, the LFO drives 4 JFETs(Junction Field Effect Transistors), which are like voltage controlled pots. As the oscillator signal rises, it lowers the internal resistance. As the signal goes negative, it increases the internal resistance of the JFET.

So now you have 4 transistors with a rising and falling internal resistance that rises and falls with the frequency of the LFO signal. One transistor per delay stage. As the internal resistance of each transistor rises and falls, it lowers and raises the frequency at which the 180 degree phase shift is occuring. This constantly changes the frequency at which the phase shift is occuring, which changes the frequency that is getting cancelled out, resulting in a subtle watery sounding wah wah effect.

A Univibe, instead of using 4 JFET transistors, it uses an LDR, which is an optocoupler. Basically an optocoupler consists of a lamp and a photoresistor. A photoresistor's resistance decreases when the lamp is bright and increases when the lamp goes dim. Each stage of the Univibe has an LDR. The LFO in the Univibe drives those lamps and causes the lamps to go bright, dim, bright, dim, bright, dim...you get the idea, at a frequency set by the speed knob. This causes the photoresistors' resistance to rise and fall, rise and fall, etc etc, causing the 180 degree shifted frequency to also rise and fall, rise and fall, etc etc.

It is because of this LDR why the Univibe sounds different from most phase shifters.

Hope this helps.

Regards,

Chris...uh...err...uh...I mean...Jon

dosmun · Post by **dosmun** » Thu Nov 18, 2004 12:17 pm

I don't need a vibe sound very much but when I do I use my Script Phase 90.

I have heard a lot of great things about the Mojo Vibe. If I was going to buy a vibe the Mojo is what I would go for.

Bluesbishop · Post by **Bluesbishop** » Thu Nov 18, 2004 8:10 pm

I'm a HUGE Trower fan...so I've used Univibes for years. the Mjo Vibe is The BEST for the bucks, but I also have the Dunlop Uni- Vibe...the BIG unit noi the small cheap one.. and it gets VERY close to the orginal in tone. I got the Dunlop Cheap from my brother..($115) so it was a cheap investment, and I can get 99% of Hendrix sounds, Trowers or Gilmours

The Mojo is better, but it cost me almost triple of what I paid for the Dunlop. Stree price on the Dunlop is around $230.00 so in your case...get the Mojo!!!

Ken

Country Boy Shane · Post by **Country Boy Shane** » Thu Nov 18, 2004 10:56 pm

How bout you just end the whole fuss about what brand to get and get a Fullton Deja-Vibe!

DaveFx · Post by **DaveFx** » Mon Nov 22, 2004 12:05 am

I have the new cream colored Fulltone Mini-Deja that I like alot.. Sounds great!!

Dave

Flames1950 · Post by **Flames1950** » Mon Nov 22, 2004 7:57 am

Country Boy Shane wrote:How bout you just end the whole fuss about what brand to get and get a Fullton Deja-Vibe!

If anyone REALLY wanted to "just end the whole fuss" they would have bought a LESLIE and ruined their backs.
I'm working on building one as we speak. 'Cause I'm POOR.

bluefuzzguitar · Post by **bluefuzzguitar** » Mon Nov 22, 2004 11:33 pm

I own both a Fender Vibratone guitar leslie cabinet and a Prescription Electronics Vibe Unit and I must say there is a clear difference between the two. The leslie literally moves air and produces the most organic 'vibe' sound you've ever heard. The PE VU is a simulation of that sound and, while getting close to a leslie sound at certain settings, can do much more than that. It can never cop the real leslie sound due to its 'wobble' but it can create the coolest psychedelic sounds at various speeds and intensities. I like them both for the unique sounds they produce. I have tried several univibe copies, including the Sweetsound Ultravibe, the Fulltone Dejavibe and the Dunlop Univibe (both the cheap and expensive version) and I like the PE Vibe Unit the best. I have tried several leslies as well and nothing beats the Fender Vibratone IMO.

Mike

McGoogle McDougal · Post by **McGoogle McDougal** » Tue Nov 23, 2004 3:21 pm

I like the Fulltone DejaVibe a lot and also think the Roger Mayer Voodoo Vibe sounds fantastic, but I got the Captain Coconut. This unit combines a fuzz unit based on a Fuzz Face, an Octavia type device, and his version of a Uni Vibe. They sell for about $400 new and I got mine used for less than $300 used. Considering the cost of most of the good sounding vibes, this is a great deal - that is if you want the other pedals. The all in one unit is very convenient and all the sections sound really great. The vibe is very tweakable and also has a jack for connecting a speed control pedal. Another plus is that you can patch the 3 effects in any order you want...

Really, all the vibe clones I've tried sound great and have their own thing going on. I agree with Mike that while Uni Vibes were originally an attempt at getting a Leslie sound, they don't really quite sound like one. Of course the flip side is that Uni Vibes do lots of things a Leslie does not do.

Eamon

gnugear · Post by **gnugear** » Fri Nov 26, 2004 1:23 pm

Well, I just found a used Mojo Vibe. I can't wait to try it out.

gnugear · Post by **gnugear** » Sun Dec 05, 2004 12:18 am

drool ... I just got my mojo vibe and I'm in heaven. I don't think I've ever loved a pedal as much as this one!

Metropoulos Forum

Any Univibe players out there?

Any Univibe players out there?

captain coconut!!!