KR - Mega Vibe

[Shitty Medeocre Tone]

Here are some pictures of my KR Musical Mega Vibe.
This is straight from the Uni-Vibe schematic with no mods.













The reason I looked inside the pedal in the first place was because as I would turn up the speed knob I noticed the sound of the vibe would thin out and I wanted to know why.

I figured out exactly why but won't post the exact reason for many reasons.


The wiring and board appears to be a sloppy mess to me.

[Shitty Medeocre Tone]

Does this only look like a sloppy mess to me?

[soulsonic]

Yeah, I agree, it does look like a sloppy mess.
But I wonder why you won't share your discovery of why the tone thins out?
Teasing isn't nice.

[bajaman]

But I wonder why you won't share your discovery of why the tone thins out?
Teasing isn't nice.

I have to agree with Soulsonic - you are teasing and likely to start a major flare up - are you a troll - I hope not, but you are behaving like one by posting this and then refusing to share information learned.
If you don't want to share, it is best to not post anything at all
bajaman

[MoreCowbell]

If you don't want to share, it is best to not post anything at all
bajaman

Probably true.

Personally I don't care either way, but psychology says that if you want somebody to be truly interested in something, then tell them that they can't have it.

[Shitty Medeocre Tone]

Since the pedal is a Uni-Vibe clone it's true to the schematic for the most part.
The difference is that it uses Millennium bypass for it's bypass operation and what is under the shroud is not correct.
Reason being you simply can not find these parts at the local parts supply or Radio Shack.

I didn't want to say this because I have zero intention of helping the KR guy out. After giving it some thought the reason I am saying so now is because I find KR to be pompous enough to not believe what I am saying here. Well, that and the task of procuring the correct photo cells is well beyond his ability.

So, why does the sound thin out at faster speeds and what does the photo cells have to do with it? The off the shelf types simply do not react fast enough to the bulb. If you check out the other popular brands you see custom made cells that were made to the spec of the original UV.

I do not make Vibes so I have no stake in any of this beyond pointing out the somewhat obvious.

[Shitty Medeocre Tone]

Here is what I am talking about.
I borrowed a couple of these from the web.
This is a vintage Uni-Vibe gut shot



Here is a gut shot of a Fulltone Deja Vibe



While I am not affiliated with Fulltone in any way I know the cells are true to the original cells.
These would react differently to a light source than one procured from Radio Shack.



My conclusion is that it would appear that the slow vibe throb is easier than the fast throb since the cells are working within their means. What separates the men from the boys, or vibes from the toys is in it's ability to do the fast vibe thing.

[Shitty Medeocre Tone]

I just found this gut shot of the mojo vibe and it looks pretty neat, layout wise, to me. I don't work or sell Sweet Sound gear so I have nothing vested in posting this shot. Actually if I did I probably would have gotten a better picture of it:




Here is the vibe schematic

http://www.univox.org/pics/schematics/univibe.gif

Here is the link for Radio Shack cells should you want to make yourself a KR clone
http://www.radioshack.com/product/index ... age=search

[soulsonic]

Okay, I understand, and I understand your reservations, but at least ths info can help out fellow DIYers with their vibes.
Thanks!

[Torchy]

Okay, I understand, and I understand your reservations, but at least ths info can help out fellow DIYers with their vibes.
Thanks!

... and has been discussed to death at Aron's. Even so far as 'scope measuring rise/fall times on several brands of photocells and optocouplers for repairing vintage gear.

Best Vibe replacements came out of the tests as PerkinElmer VT33N2s.
http://www.alliedelec.com/Search/Produc ... 080A35E17F

Smallbear has acceptable alternatives - these are the discontinued Mouser stock that Steve bought out :-
http://www.smallbearelec.com/Detail.bok?no=343

Mr. KR should read this :-
http://optoelectronics.perkinelmer.com/ ... ecting.pdf

[soulsonic]

I learn something new every day!
Thanks Torchy!

[AA1983]

The difference is that it uses Millennium bypass for it's bypass operation and what is under the shroud is not correct.
Reason being you simply can not find these parts at the local parts supply or Radio Shack.
.

It would be great if you would post a pic of whats under the shroud in the mega vibe.

What does it mean that the bypass is a Millenium bypass, and how does it affect the sound?

[R.G.]

What does it mean that the bypass is a Millenium bypass, and how does it affect the sound?

The Millenium Bypass has no effect on tone/sound quality whatsoever.

[Starman]

I own a Megavibe and an original Univibe from around 1970. At top speed the Univibe thins out more than the Megavibe and I think the Uni sounds better. The Mega as too much wobble, I wish the intensity would go down a little as I turn up the speed.

[Shitty Medeocre Tone]

I own a Megavibe and an original Univibe from around 1970. At top speed the Univibe thins out more than the Megavibe and I think the Uni sounds better. The Mega as too much wobble, I wish the intensity would go down a little as I turn up the speed.

Could be something wrong with your original if it is thinning out!





If you look at the LED arrangement in this Rat schematic it is what is commonly referred to as "Millennium bypass". It seems that since the 3PDT switch is as cheap as a DPDT many prefer to not use Millennium bypass since there is less to go wrong over time.



Here is the oscillator circuit of the original Uni-Vibe.
The bypass shorts the 47k off of Q13.
This is done through a momentary switch in the heel of the foot controller.
In essence this is not true bypass nor is it Millennium bypass.
The light bulb would stay slightly lite and the signal is still going through the circuitry of the vibe.
This will color your tone regardless if the pedal is on or off.
The cool thing about it is that as soon as you rock the pedal forward the effect comes on and starts with a slow wobble and increases speed as you progress forward on the rocker.
The pedal will not function with out the foot pedal as it's a part of the circuit.

The clones have all gone true bypass and not all have expression pedal capabilities.
I don't know but would think this route was taken in order to not color the tone and since true bypass is so popular with many players.

I wonder if anybody will make a Uni-Vibe like the original or if there is a demand for such a thing.

Any thoughts?

[Starman]

The cool thing about it is that as soon as you rock the pedal forward the effect comes on and starts with a slow wobble and increases speed as you progress forward on the rocker.................I wonder if anybody will make a Uni-Vibe like the original or if there is a demand for such a thing.

Any thoughts?

I don't care for the Cancel/speed pedal feature on mine. I'd rather be bypassed than canceled, so I stick it in a loop. One big reason is the volume drop when it comes out of cancel. By grounding that transistor, the phase shift stops and you get full signal. When effect is kicked in, phasing starts and is subtracted from the siginal. There's a volume drop that can't be fixed.

If I was putting on an afro and doing Jimi tribute I might want the original configuration, curly cords, non-TB wah, etc

[GBlekas]

I don't care for the Cancel/speed pedal feature on mine. I'd rather be bypassed than canceled, so I stick it in a loop. One big reason is the volume drop when it comes out of cancel. By grounding that transistor, the phase shift stops and you get full signal. When effect is kicked in, phasing starts and is subtracted from the siginal. There's a volume drop that can't be fixed.

If I was putting on an afro and doing Jimi tribute I might want the original configuration, curly cords, non-TB wah, etc

LOL. That's pretty funny

[Torchy]

Yes

First off, the Millenium Bypass is NOT what is in the RAT. The MB was developed by R.G as an extension/improvement to the RAT bypass using more reliable led illumination (the fet is switched with the leakage from a reverse biassed diode/pn junction), and avoiding the faint 'pop' from the pulldown. THE MB IS TRUE BYPASS without pops. The fx is completely disconnected from the circuit, the fx only provides a dc path to ground to light the led. When 'on', the MB is completely disconnected from the cct. No tone suck, at all. Period. For the facts and history, RGs article is brilliant ......... http://www.geofex.com/Article_Folders/bypass/bypass.htm

Secondly, the original Univibe switching is a pain. The footpedal connector is awful, and damages easily. You dont have the option of using it stand-alone, and the pot was baaad quality in the originals Ive had. By leaving the bulb on full illumination for possibly 2 hours live, up to 6 hours rehearsal, they didnt last long. The effect on tone was awful in the cancel postion (IME) - I bet for every original vibe left intactus another 20 were properly bypassed.

Lastly, the cds photocells on originals will have aged by now, and years of operation will degrade the cds reaction time. This will indeed lead to thinning out at higher speeds - theyre one of the most common refurb requests. The photocells I mentioned above are what I use to keep the originals working at their best, but retain their value to the best extent.

I have only had two vibes (from working musicians) that had not been tru-bypassed, and most owners wanted a better foot-controller. Not one asked me to put the original 'cancel' back, a local collector did however, but that was a rebox into a mint condition case and purely for resale kudos (and hence ££££).

Purely my experiences, ymmv

[Shitty Medeocre Tone]

Yes

First off, the Millenium Bypass is NOT what is in the RAT. The MB was developed by R.G as an extension/improvement to the RAT bypass using more reliable led illumination (the fet is switched with the leakage from a reverse biassed diode/pn junction), and avoiding the faint 'pop' from the pulldown. THE MB IS TRUE BYPASS without pops. The fx is completely disconnected from the circuit, the fx only provides a dc path to ground to light the led. When 'on', the MB is completely disconnected from the cct. No tone suck, at all. Period. For the facts and history, RGs article is brilliant ......... http://www.geofex.com/Article_Folders/bypass/bypass.htm

Secondly, the original Univibe switching is a pain. The footpedal connector is awful, and damages easily. You dont have the option of using it stand-alone, and the pot was baaad quality in the originals Ive had. By leaving the bulb on full illumination for possibly 2 hours live, up to 6 hours rehearsal, they didnt last long. The effect on tone was awful in the cancel postion (IME) - I bet for every original vibe left intactus another 20 were properly bypassed.

Lastly, the cds photocells on originals will have aged by now, and years of operation will degrade the cds reaction time. This will indeed lead to thinning out at higher speeds - theyre one of the most common refurb requests. The photocells I mentioned above are what I use to keep the originals working at their best, but retain their value to the best extent.

I have only had two vibes (from working musicians) that had not been tru-bypassed, and most owners wanted a better foot-controller. Not one asked me to put the original 'cancel' back, a local collector did however, but that was a rebox into a mint condition case and purely for resale kudos (and hence ££££).

Purely my experiences, ymmv

I am not trying to start a pissing match and with all due respect I say the following.
Look at RG's MB and look at the Rat. It's the same thing bypass wise.
I think RG developed MB to be another internet myth with little truth beyond coining the name for the design.

Here we go...."RG's design" (borrowed from the link you put up)


And the Rat design (borrowed from the AMZ site)


Looks like a mod made to the Rat bypass.
They are pretty near identicle, imho.

I can see your point about the original UV's.
The reactance to the cells diminishing over time makes perfect sense too..
Of course this issue would happen even in a new pedal over time.
The DIN plug issues etc....
Still, I think the orignals look really cool and wouldn't mind having a new one.

[Mayniac]

Look at RG's MB and look at the Rat. It's the same thing bypass wise.
I think RG developed MB to be another internet myth with little truth beyond coining the name for the design.

WTF??!!