Gonna build an optical vibe!

[tedmich]

Having poured over the original schematics for the Shin-Ei and looked at its >$1k modern versions (Funky-Vibe, Deja Vibe) and familiarizing myself with the available CdS photocells, their spectral response, time constants and resistance curves, as well as the reflective spectrum of polished aluminum, silver and copper

I've decided to make a vibe kit from Forum Vibe, version 5 , since its flexible, allows for fine tuning the response to the incandescent bulb and is altogether dialed in on a nice PCB about 1/2 the size of the original.

A full kit is about $60 from Germany Das Musikding (verkauf@musikding.de)
also https://www.classicamplification.net/fv/

and I think a Hosa FSC-385 will fit it all well.

sounds here

[Jazz P Bass]

Nice!

[Mick Bailey]

For a good while I've been thinking about building a Univibe to the original spec as much as possible, but I was unable to get hold of an original to replicate the PCB artwork and take accurate measurements, so shelved the idea. It's still on my to-do list, though. As an interim project I built the Hollis Easy-vibe when I first saw that schematic - just a fill-in to go on my pedal board. What did surprise me is just how good that circuit can sound and with careful adjustment can give that asymmetric modulation of the original. It beats all of the reissues I've heard in real-life and despite what ought to be serious deficiencies in cell response, bulb latency and illumination curve and housing reflections, it works superbly. Regrettably, I sold this last year and really miss it, though it is getting used a lot by the new owner. Maybe time to revisit the Univibe, though I'm keen to discover how the Forum Vibe works out. Despite the success of the Easy-vibe, I still think if an LED setup can sound this good, just how good can an incandescent circuit sound if its done properly.

[nosaj]

Who wants to build this?
nosaj

[mozz]

There's a few places selling univibe pcb's. Here is one in UK.
https://reverb.com/item/43314448-uni...-shin-ei-honey

I actually have a pcb here and bought some cds cells but not sure the spec is right, i have to do more research on that part.

[Mick Bailey]

That PCB looks pretty good and in the UK, too. I have 4 LDRs in my stash of parts somewhere that are the correct spec. They were used in some projectors as well - for the audio.

[tedmich]

there are several new "vintage layout" PCBs for the UniVibe on ebay one being sold by a guy who has made somewhat crabby Youtube videos where he repeatedly mocks the current price of the original. Quite amusing!


https://www.ebay.com/itm/26494739147...QAAOSwfmFfuaHS


another Ebay board
https://www.ebay.com/itm/28367155854...cAAOSwsKddG2-I

The development cycle on the Forum Vibe version is truly impressive, a classic DIY redevelopment group effort! Check Jetster's build about 1/2 way down this thread at DIYStompboxes.com for one of the most feature packed (kitchen-sink!) and compact builds

https://www.diystompboxes.com/smffor...topic=78009.20

(yes thats a polished copper pipe cap to create the optical chamber, supplemented with a glass silvered mirror up top to offset the noted drop off in coppers reflectance near the 615nm peak these CdS photocells have...all very complex ; )

[g1]

How often would you have to re-polish that copper?

[52 Bill]

Thirty plus years ago, I did a lot of work with a bunch of guys that were really into Hendrix and all of the FX that he used. I was making Fuzz Face clones, modifying wahs, building octavias and cloning Uni-Vibes.

One Uni-Vibe repair required the replacement of the original pc board. The former owner replaced every component on the board for one reason or the other. He must have used a 80 watt iron, so there were burnt sections of phenolic and too many lifted traces to make repairs worthwhile. I copied the original board and made replacements using the photo emulsion method. Later on I created a new design that would fit into a Cry Baby pedal case. There really wasn't a lot of money in doing them, but they were fun to figure out.

I found the artwork and will attach it here for anyone to use.

[tedmich]

Thanks Bill! I wonder how close that layout is to the pedal sized Deja Vibe Mini that Fulltone sells?

also do you have a schematic or silk layout for that board?

[Mick Bailey]

Another optical incandescent bulb pedal I wanted to build for a while is the 8-stage Schulte Compact Phasing A. I was looking round for a stripboard layout without success, so will end up doing my own layout from the original schematic. It needs 8 matched LDRs which are no longer available so some experimentation will be needed.

[tedmich]

Another optical incandescent bulb pedal I wanted to build for a while is the 8-stage Schulte Compact Phasing A. I was looking round for a stripboard layout without success, so will end up doing my own layout from the original schematic. It needs 8 matched LDRs which are no longer available so some experimentation will be needed.

Neato ! The Catch the Rainbow sound! That was the first album I bought ! And no Aiwa reel to reel required! Here is a DIY I found
http://jhaible.com/legacy/compact_clone/

the PCB looks hairy! https://www.thonk.co.uk/shop/haible-...ck-phaser-pcb/

[Mick Bailey]

Shame the PCB is no longer available. The original schematic is much simpler and modern voltage regulators can be substituted. I would probably dispense with the DIN sockets in favour of the later revised arrangement of the clone you linked to.

[Mark Hammer]

Another optical incandescent bulb pedal I wanted to build for a while is the 8-stage Schulte Compact Phasing A. I was looking round for a stripboard layout without success, so will end up doing my own layout from the original schematic. It needs 8 matched LDRs which are no longer available so some experimentation will be needed.

FETs need to be matched in phasers, such that there is no point in the sweep cycle where one or more of the FETs are not changing drain-source resistance. One measures their electronic properties, matches them for Vgs, and can then set the required bias voltage/current to nudge them all into their linear operating range. That's why most, if not all, FET-based phasers have a trimmer on-board. LDRs, however, are not subject to such right/wrong biasing errors, and will continue to change resistance in response to changes in illumination. Few, if any LDRs will ever be faced with illumination SO intense that their resistance can't drop any further.

What matters with phasing is that ALL stages contribute to cumulative phase shift across stages that keeps moving where the maxima is. LDRs help if they are in the same general ballpark, I suppose, but as long as they change resistance in response to illumination-source, they will contribute to cumulative phase-shift.

On a tangential note, I built myself a phaser pedal that is essentially two Phase 90 clones in series. They can be individually swept, OR synced to a common LFO. I can lift the dry signal from the first one, such that I'm feeding a 4-stage phaser with a 4-stage vibrato. VERY interesting and pleasant textures. It has me curious about what a Vibe effect fed by a slow phaser would sound like.

[Mick Bailey]

I wonder if the optos varied so much back when this circuit was designed that they specified selected parts. Or maybe the schematic is marked such but actually they didn't bother. Not matching them is a bonus, though In any case the last batch of 100 I bought are all pretty close and work well with both incandescent and LED illumination.

That's a nice phaser you've built and the vibe sounds are good. I want something like this for my Modular synth (now guitar powered) - a regular phaser gets lost on synth sounds.