Restoring the Jimi Hendrix Univibe - Page 1
Forum section: electronics / general

author: Frantone
author_rank: Regular Contributor
timestamp: March 23, 2013, 05:51:05 pm
content: In 2001 I had the very rare opportunity to restore one of Jimi Hendrix's toured Univibes - a true piece of history!The unit had not functioned for years but the owner wanted it to be operational again. It had some interesting modifications to the circuit board. One interesting feature was that the screw- down opto shroud had been replaced with a duct tape covered RCA Vacuum tube box top which had been adhered to the PCB with white glue. Why I have no idea, but it may have increased response because it was larger than the original shroud and perhaps because it was made of white cardboard it diffused the light better.So you may be asking yourself if I played the pedal after the restoration was complete? I did.The pedal had so much mojo it brought tears to my eyes! What a sound - and words fail to describe such a thing.Anyway, I thought I would share this one with you EEVBloggers this weekend - ENJOY!

author: SeanB
author_rank: Super Contributor
timestamp: March 23, 2013, 05:59:35 pm
content: What was wrong with it other than just poor connections? +10 for the showing of it.

author: Frantone
author_rank: Regular Contributor
timestamp: March 23, 2013, 06:09:03 pm
content: There was surprisingly little wrong with it considering the mileage - It needed the ubiquitous recapping and the opto bulb needed replacing. Most of the work involved repairing the mechanical parts of the foot controller and interconnects.

author: SeanB
author_rank: Super Contributor
timestamp: March 23, 2013, 06:16:33 pm
content: Always the same parts that fail, transistors got very reliable very early on in their development, and have remained so basically since then. Same with film capacitors and those carbon composition resistors that would drift, go noisy and otherwise misbehave but keep on working. Still have a box of them around, and still use them when I want to have a nice old style resistor in a non critical application.Looks like that unit was made mostly with good quality Japanese made transistors and capacitors.

author: Frantone
author_rank: Regular Contributor
timestamp: March 23, 2013, 06:44:24 pm
content: It was well designed and very rugged for it's time - Most effects pedals of that era were filled with parts made of wood and tin foil kinda strung together.

author: Biff383
author_rank: Regular Contributor
timestamp: March 23, 2013, 06:48:59 pm
content: Thanks

author: Unknown
author_rank: Unknown
timestamp: March 23, 2013, 07:20:45 pm
content: Ever since I heard "Machine Gun" on the "Band of Gypsys" album i've always wanted one of these!

author: Frantone
author_rank: Regular Contributor
timestamp: March 23, 2013, 08:32:35 pm
content: The owner of the Univibe had gotten the pedal from Hendrix himself - so to speak. He was a teenager living in NYC early in 1970 and was in Manny's Music in Midtown when Hendrix came in with a box of gear he wanted to sell to the store. When Hendrix left, the guy went to the clerk and said he wanted to buy one of the things Hendrix had dropped off, and the clerk said sure - there were three Univibes in the box, two of which did not work, and this one did so cash was handed over and he got his Hendrix Univibe. Hendrix had a studio in New York that was in trouble financially, so this seems to be part of that time.

author: mamalala
author_rank: Unknown
timestamp: March 23, 2013, 10:16:06 pm
content: Don't get me wrong, but i think one of the main reason such (old) effects are "heavenly" is because of their simplicity and less-than-average wiring. I have seen a lot of the modern units, with convoluted circuits, cabling done extremely nice, etc. But you never get the crackle & vibe that you get with these old units. I'm pretty sure the reason is _not_ because we nowdays can produce more stable resistors, or have better processes to produce transistors....Greetings,ChrisP.S.: It's always an extremely satisfactory thing to show these things to audiophools. After all, what they listen to is actually generated by these things. What good is a 4k+ power supply cable if you look at what these olden day effect circuits do....

author: ivan747
author_rank: Super Contributor
timestamp: March 24, 2013, 01:07:40 am
content: I always wanted to come up with a novel distortion pedal. Two year on and I still get ear-bleeding sound when playing a single note. You don't even want to hear a chord

author: mamalala
author_rank: Unknown
timestamp: March 24, 2013, 01:50:38 am
content: Quote from: ivan747 on March 24, 2013, 01:07:40 amHint: Many tubes work just fine with a rather "low" voltage. Stuff like 24 volts is OK for a lot of triodes. Easy to generate as well, considering that you don't need much current. Of course the filaments are alwas a huge power hog...As for transistors or FET's, try to drive them so that "just somewhat below" full conduction results in full gain. FET's are somewhae better for this, since their characteristics are more tube-like. Another thing is to use a rather hig impedance suppy/bias source compared to the signal. This will cause additional distortion since the supply will break down in voltage at higher spikes....Avoid high capacity for the supply, you surely do not want it _that_ stable. In general, tend to design it towards the "owrst case possible" regarding that stuff, instead of things like "really stable supply!". Keep in mind that the 9V batteries usually used in pedals are rather high impedance and low cacaity.Greetings,Chris

author: Quick5pnt0
author_rank: Contributor
timestamp: March 24, 2013, 03:08:47 am
content: I don't have much to add other than to say how awesome it is that you got the chance to handle something like that from the great Hendrix!

author: Frantone
author_rank: Regular Contributor
timestamp: March 24, 2013, 03:37:06 am
content: Quote from: mamalala on March 23, 2013, 10:16:06 pmI don't subscribe to the idea that old pedals sound heavenly by default - but this Univibe certainly did - and for may reasons. One being that I had restored it to proper function (which is seldom the case with vintage pedals) and it is a very good stable design. That cannot be said of most other commercially made effects of the 1960's.

author: Frantone
author_rank: Regular Contributor
timestamp: March 24, 2013, 03:47:37 am
content: For contrast - here is a pedal that Manny's Music actually made themselves and sold in the early 1970's - Manny's Fuzz. I restored this pedal in 2002. It is more common for its time.

author: rama claproth
author_rank: Newbie
timestamp: March 24, 2013, 10:42:01 am
content: UniVibe owned by Jimi!!! WOW that's so HOLY!!! Thank you for posting this!BTW I notice there is a capacitor under the board, what is the value of the cap? Is it in parallel together with the 15nF?

author: Frantone
author_rank: Regular Contributor
timestamp: March 24, 2013, 06:22:20 pm
content: Quote from: rama claproth on March 24, 2013, 10:42:01 amIt is a .005uf ceramic original 'bodge' in the feedback loop of one transistor. Not uncommon for RF issues.

author: Frantone
author_rank: Regular Contributor
timestamp: March 24, 2013, 06:25:16 pm
content: Quote from: SeanB on March 23, 2013, 06:16:33 pmIt is true - even the earliest silicon transistors drift relatively little over time, and if the circuit is properly balanced usually need no rebiasing.

author: SeanB
author_rank: Super Contributor
timestamp: March 24, 2013, 06:34:34 pm
content: My PC amplifier is a 1070's vintage National Panasonic quad control centre, mostly used as volume control and input switching. Only thing I did to it was to replace the power lamp with a LED, and to replace almost all of the electrolytic capacitors in it, as they were getting iffy. Still has the original PNP transistors, even though they are using a RF mixer transistor, probably as it was a device with a guaranteed low noise figure. Made the power supply a lot bigger capacitor wise, from 100uF to 2200uF, it will run for over a minute on power off before it starts to distort the output at under 3v supply from the normal 30V.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: March 24, 2013, 08:03:20 pm
content: That makes my heart pound when I see folks restore old stuff like this, very exciting. Especially when it has a legend attached to it. It is very cool of you to share this. You Rock!!75 percent of the repairs I do here in my shop are tube related equipment. And the rest are early solid state equipment. Some with over 3500 volts on the plates, which will zap you a good one.I just finished a 1954 National NC-98 receiver. That was fun. No paint job just restored the functions of it. Was so excited with it I had to post it on an old radio forum I am a member of.

author: Frantone
author_rank: Regular Contributor
timestamp: March 24, 2013, 10:47:29 pm
content: Over the past 20 years I have resorted a lot of antiques - in the '90's I had a part time antique radio repair and resto business, and after I got to NYC in '98 I was sought by local artists to restore vintage pedals. Tubes? You betcha. Just look at my blog!

author: Radio Tech
author_rank: Frequent Contributor
timestamp: March 25, 2013, 12:22:38 am
content: Sounds cool, I look it up. Thanks again for sharing.

author: rama claproth
author_rank: Newbie
timestamp: March 25, 2013, 03:10:31 am
content: Quote from: Frantone on March 24, 2013, 06:22:20 pmRF you mean as radio frequencies? I never notice the Univibe pickup radio signals like the Fuzz Face. Correct if I'm wrong but looks like the cap under the board is joined with the 15nF if I'm not mistaken, which it does connects with the middle leg of the transistor and the 4K7 resistor.Thanks for the reply Fran

author: Frantone
author_rank: Regular Contributor
timestamp: March 25, 2013, 04:06:26 am
content: Quote from: rama claproth on March 25, 2013, 03:10:31 amIt is a bodge that is not uncommon. High gain transistor or op amp stages can oscillate at high frequency and the cap is in there to stop this by creating filtered feedback. You wouldn't pick up detected audio from local radio signals, per se.

author: rama claproth
author_rank: Newbie
timestamp: March 25, 2013, 04:54:06 am
content: Quote from: Frantone on March 25, 2013, 04:06:26 amHmmm got it. I notice the footage from the Isle of Wight, Jimi was having trouble with radio frequencies and he stopped using the UniVibe during the show and all went okay. So the radio frequencies must be coming from the UniVibe because he kept on using the Fuzz Face with no trouble. So it could be on that show his UniVibe didn't had that cap. Aha! Thanks for the info Fran

author: Frantone
author_rank: Regular Contributor
timestamp: March 26, 2013, 12:10:42 am
content: Here is a capper for this thread - my bodging/mod of a vintage late 1960's British made WEM Copy Cat tape delay. Notice the tack soldered resistors and a heat sink for one of the original germanium transistors (yes, it got hot!). New electrolytics - can't help that. A very bad design to begin with, and very poorly soldered over all, but I kept it as original as possible with some minor mods to reduce noise.

author: ivan747
author_rank: Super Contributor
timestamp: March 26, 2013, 01:54:52 am
content: Can you show us the actual tape? O0

author: Frantone
author_rank: Regular Contributor
timestamp: March 26, 2013, 03:49:57 am
content: The tape loop is in place in the upper photo.

author: jcook1979
author_rank: Newbie
timestamp: March 26, 2013, 06:47:46 am
content: That's a trip...I've never seen anything like that Copicat delay. I see five tape heads, up top; which are for recording, and which are for playback?

author: ThunderSqueak
author_rank: Unknown
timestamp: March 26, 2013, 08:19:26 am
content: Restoring those old pedals is funThanks for sharing! I love it when people bring me old amps and pedals to fix because it means I can legitimately bring my tele to work for testing

author: grumpydoc
author_rank: Super Contributor
timestamp: March 26, 2013, 08:20:17 am
content: Ye Gods - haven't seen one of the Copycat's for a long time.QuoteLeft to right: erase, record, 3x playback I think

author: ivan747
author_rank: Super Contributor
timestamp: March 26, 2013, 11:34:08 am
content: Quote from: Frantone on March 26, 2013, 03:49:57 amOh,thatI thought it would have like a cassette inside. This thing is like 2-3 times older than me

author: StevenB
author_rank: Contributor
timestamp: March 26, 2013, 12:38:30 pm
content: As a guitar player and with effects pedals being the reason I got into electronics (back when I was a teenager) I want to thank you for this post!!! It made my day. Also, it doesn't hurt that I'm a Hendrix fan.Way cool.

author: Frantone
author_rank: Regular Contributor
timestamp: March 26, 2013, 03:17:23 pm
content: Quote from: jcook1979 on March 26, 2013, 06:47:46 amOkay - the tape loop moves counter-clockwise, and left to right there is a stationary alnico magnet in the tensioner arm for a pre-erase, then the active erase head, then the record head, then three individual playback heads, each of which can be selected or combined with the white buttons. The effect was great, but apart from live shows where the background noise of the club was ear shattering the unit was unusable. So noisy!Here is an example of me playing through the WEM:

author: Frantone
author_rank: Regular Contributor
timestamp: March 26, 2013, 03:27:25 pm
content: Quote from: ThunderSqueak on March 26, 2013, 08:19:26 amWhenever I end up working for someone else, I always make sure a guitar and amp is at my workstation! Like here, at Electro-Harmonix in 1999:

author: jcook1979
author_rank: Newbie
timestamp: March 26, 2013, 04:51:14 pm
content: Quote from: Frantone on March 26, 2013, 03:17:23 pmCool! It's interesting to see vintage equipment restored to working condition. And great vid, too; awesome choice of music (Grieg). Well played.

author: krivx
author_rank: Frequent Contributor
timestamp: March 26, 2013, 04:54:14 pm
content: Were you involved with the tube testing gear that they have at EHX? Do you mind telling us about it?I really liked the Peach Fuzz btw, unfortunately I've only ever played with a clone

author: Frantone
author_rank: Regular Contributor
timestamp: March 26, 2013, 06:39:27 pm
content: Quote from: krivx on March 26, 2013, 04:54:14 pmThe Peachfuzz clone is not the same tonally. Yes, I built those EH machines.http://www.frantone.com/designwritings/design_writings3.html#burner

author: krivx
author_rank: Frequent Contributor
timestamp: March 26, 2013, 07:24:05 pm
content: Quote from: Frantone on March 26, 2013, 06:39:27 pmThese are very impressive. I haven't seen many high-voltage regulated supplies for tube stuff.The clone I played with was on a breadboard and was based on an internet schematic, not one of the commercially produced clones. It may not have been correct as to the original Peachfuzz but it did sound great.

author: Frantone
author_rank: Regular Contributor
timestamp: April 02, 2013, 03:40:37 pm
content: Jump to 12:00 for the show!https://www.youtube.com/watch?feature=player_detailpage&v=B0tu_JpypEA#t=684s

author: Six
author_rank: Contributor
timestamp: April 02, 2013, 05:58:08 pm
content: Audio Pron!Thank you so much for sharing this! O0

author: Frantone
author_rank: Regular Contributor
timestamp: April 03, 2013, 03:22:03 am
content: Here's the last of it - I found a couple more pics that show the foot controller before and after. The foot controller had no base, just foil paper and tape - a patch job done at some point long ago by the owner - but it had to be removed to do the repairs. I fabricated a new base plate and it got all new inner workings.I think this is the most read thread I have ever posted here..... Pegged the meter!

author: rama claproth
author_rank: Newbie
timestamp: April 07, 2013, 10:46:32 pm
content: Quote from: Frantone on March 25, 2013, 04:06:26 amI don't think it has to do with RF's in this matter. That spot needs to be 15nF. In those times they use whatever they could use to make it 15nF. Check out these pics for more detail. Photos are from Brad Burt (http://classicamplification.net/)

author: gabe
author_rank: Newbie
timestamp: April 08, 2013, 12:57:11 pm
content: Wow that is awesome. I just picked up a nice uni vibe, its clean but it stopped working, The LFO, I assume, dont know. But want to get it fixed, I think its a simple fix, because everything else seems to be working, bulb lights up powers on, ect. any advice?

author: Randall W. Lott
author_rank: Regular Contributor
timestamp: April 09, 2013, 03:00:53 am
content: Thank you for sharing!I'm a musician and an EE, so I appreciate the importance of something like that!