Neovibe lamp - ldr arrangement

[alfafalfa]

Redhouse,

What sort of leds did you use , I mean their range ?

Alf

[alfafalfa]

No reply to my own post .. but I just found I had made a mistake with the speedpot.
Mine has 4 pins x2 that is and  one of the outer pins  I used by mistake , it's  going to the pot's housing.
So I corrected this and now it's working better.

While doing this I took off the canister's top  to see if the light was working properly and now I am sure that the amount of reflection from the foil in the cap reflected back to the ldr's has a lot to do with the sound.
It changed definitely when I put the cap back on.
And  how much of the light is reflected and its diffusion must also be taken into account.
The ldr's are now pointing upwards and don't get any direct light from the lamp which is below the ldr's now. Just the reflection.

these are my findings so far.

Alf

[RedHouse]

Redhouse,

What sort of leds did you use , I mean their range ?

Alf

LED's?

[RedHouse]

R.G
As usual...you are teaching the man HOW to fish.

Cracks me up sometimes, as folks want to move on, try other things, alternative builds, thank heaven someone's willing to save us lost lambs just wandering around aimlessly in the fog all confused about what we are doin, wow it's good to be alive! 

Now then, where's that bait-can and soldering iron, I've got stuff to build ...and test ...for myself.     

[alfafalfa]

Redhouse,

What sort of leds did you use , I mean their range ?

Alf

LED's?

Sorry redhouse, I meant LDR's of course  !!   

What is the value  in light and  in darkness ?

By the way , I had another look at the original ldr's in the Univibe and realised that  these only pick up light from above while mine also pick up some amount from behind .
I am right  that they are somewhat light sensitive from the back too ??

So I may have to try and  lightproof them from the back.

Alf

[RedHouse]

Sorry redhouse, I meant LDR's of course  !!   

What is the value  in light and  in darkness ?

By the way , I had another look at the original ldr's in the Univibe and realised that  these only pick up light from above while mine also pick up some amount from behind .
I am right  that they are somewhat light sensitive from the back too ??

So I may have to try and  lightproof them from the back.

Alf

I have used all these:

These work very well:
54C679     50k~200k/Lt  20M/Dk (Mouser)
NOTE: Small Bear has them now and I believe this is the LDR that RG recommends for his Neovibe.
(check his PDF to be sure)

These are a little cheaper and also work work very well:
G15177   1k-4M  (Electronic's Goldmine)
G15176  1k-20M  (Electronic's Goldmine)
G15396 - cut in half   (Electronic's Goldmine)
using only the LDR side, these worked surprisingly well but all were not the same,
I had to cut open like 6 or 7 of them to find 4 with the same LDR.

I like these better but they are more spendy:
NSL-5540   30k/Lt  20M/Dk (Allied)

and these will also do the trick:
NSL-5152   15k/Lt   5M/Dk  (Allied)
NSL-4140   14k/Lt   8M/Dk  (Allied)



If light bleeding through from the back is a concern (other than your lamp being behind your LDR) the LDR's in the hermetically sealed Metal-Can package with the little glass windows are the ones to use.

The old brown circuit boards in the original univibes look (from pic's) as though they were better at blocking stray light from entering the rear of the light box, maybe better than the green epoxy (FR4) boards we use these days?.

Which reminds me of a story, I've had to address this in the past by spray-painting a small circle of flat black on the board (before loading any components) where the light shield is going to be, this keeps out external light when I have to have the boxes open for adjustment etc, you can see in this pic.
(I don't use RG's black film can method)

I use a different light sheild, one of my own idea's, it is a little more hastle to build (but at least it's mine). It's made from a 3/4" copper pipe end-cap bought at the local DIY store for like 99¢, it has to be cut down a little because one of my design goals was the light box can't be very much taller than the tallest component on the board which currently are those stacked film caps. My boards all have a triangle of 3 solder pads and the light shield is soldered down to the board as can be seen in the pic's below.

As the story goes, my Vibe-Baby board turned out to have an issue with stray light. It never occurred to me when I built the first unit until the user came back after a gig and reported "it sounded different" at his gig, I puzzled over this for a while and looking over the unit from time to time I couldn't really tell why....until one day as I was looking across the room at my VOX 847 sitting over there on the floor, it dawned on me ...the wah shell has a big 'ol hole in the top under the pedal where the pot is mounted which when the pedal is back, is quite open to the elements. The guy's band  uses stage lighting ...hmmm.

Could it be? well to be true to my MO (which is: let's just test that theory!) I plugged the Vibe-Baby into a guitar and amp, grabed a 4-cell maglite and shined it on the pedal from across the room and yep ....it 'vibed!.... well it was back to the think-tank for me (that's what I call it when I'm sitting at my bench doing nothing ...the think-tank) and that's when I came up with my current system as shown below which works well and keeps to the goal of not modifying the wah shell:

A vintage layout Vibe-Baby (Electro's and Mylar caps, no bulb-offset or mixer trim pots)



here's a pic of my lightbox system in my testbed-box, this is my go-to box for 'vibe experimenting:
(built into a Data switchbox I got for 50¢ at the charity shop)



Note the chart taped to the lid which shows the capacitor
values on each of the four 5-position switches, way easier
than soldering and re-soldering new cap's for testing.



In looking at your latest pic, with your LDR's standing-tall with bulb-in-socket for testing purposes, it seems to me you could just slip a piece of black shrink-tubing over the bulb leaving the top open that should shroud the bulb enough to keep from directly lighting the LDR's (set them equal height to the bulb)

BTW; the pic above was my 1st Vibe-Baby, after two of those (one for JC) and a few other non-WahShell boards, I have switched from flat-black inside the cover (light shield) to flat-white (or just polishing it and spraying matte-clear).

After this recent 'round of experimenting I'm leaning toward changing to mounting the LDR's facing straight-up (like the original) and partially covering the bulb sides so it has to shine upward using more bounced light and less (if any) direct light. 

-Brad

[BubbaKahuna]

I got some of these from AllElectronics.com for my impending Vibe build.



They're highly polished stainless steel mirrors. I should be able to get 2 light boxes out of each one (obviously more than I'll need). They're kind of thick so it'll be a challenge to bend them, but I'd think they'll give about the best reflective light inside the box of anything you could make or buy. They're extremely well polished and look just like the one in the stock picture above. Best part is they're 5 for $1.

I'm just wondering if something this highly polished is really the best for the Vibe application.  Maybe adding some fine sanding to disperse the reflected light would be better? I also have access to glass bead blasting. It'd still be reflective to light, just not in an image kind of way. I have several of the mirrors, maybe I'll make a couple differently and swap them out to see what works better. I'll post results here of course.

Cheers,
- JJ

[R.G.]

You're working too hard at it.

Light mixing chambers are an old technology for making light distribution uniform across an area. They work best if the entire interior is highly reflective and also non-planar. A crinkled shiny surface spreads the light around and evens it out. Just gluing the shiny side of kitchen aluminum foil in there works fine.

[alfafalfa]

Thanks Redhouse for the very extensive explanation.
You gave me some very useful clues.
The black canister is also "open " at the bottom where I glued it onto the board so I'm going to paint this part black and  try a little wrinkled foil as an inside lining.  The cap has already had that treatment.
( must redo it I notice ! )



Any suggestions for good univibe examples to use for the reference sound besides the common ones:
Pink Floyd, Jimmy , Robin Trower ??

Alf

[RedHouse]

Any suggestions for good univibe examples to use for the reference sound besides the common ones:
Pink Floyd, Jimmy , Robin Trower ??

Alf

Nope, you're on your own there friend, the univibe means different things to different folks, like 'ol David Gilmore makes his sound way different than Robin Trower, there are lots of different styles and applications for the 'vibe.

As for me, I like Robin Trower's sound in Bridge Of Sighs, the outro to Too Rolling Stoned, the studio version of Daydream, all of which use different speed and intensity settings. My favourite Gilmore might be Time. My favorite Hendrix is definately Machine Gun from Band Of Gypsis.

The Trower sound relies heavily on adding reverb, the 'vibe by itself doesn't Trower well without some kind of delay.
(after the vibe, and normally after OD)

Speaking of Machine Gun, some time back on the trading forums I managed to do a B&P's and score a copy of the whole new years eve show(s) both early and late, interestingly in the early show Hendrix has his univibe set totally different, it sounds like it's on the vibrato setting at full intensity (has that wild out-of-tune wang sound).

[RedHouse]

You're working too hard at it.

Light mixing chambers are an old technology for making light distribution uniform across an area. They work best if the entire interior is highly reflective and also non-planar. A crinkled shiny surface spreads the light around and evens it out. Just gluing the shiny side of kitchen aluminum foil in there works fine.

C'mon now RG, don't be a buzz-kill, let us experiment with our stuff.

Fiddling around with film can's could be considered working too hard too buddy. 

[Tony Forestiere]

Sorry for reviving this...
Has anyone tried spraying/painting the interior of the light box flat white? According to the additive process of color theory, a white surface reflects all colors of the visible spectrum equally (400nm-700nm, or visible RGB). Using a flat paint texture would even out the lamps reflectance by eliminating glare in areas of the chamber.

just my $.02

[smallbearelec]

The lamp need not be 12 volt. 1.5 volt lamps have been tested and are known to work in the Neo with correct biasing. I offer both a leaded and a socketed version:

http://www.smallbearelec.com/Detail.bok?no=645

http://www.smallbearelec.com/Detail.bok?no=646

I mention this particularly for overseas builders who don't have access to those Radio Shack parts.

Regards
SD

[RedHouse]

Sorry for reviving this...
Has anyone tried spraying/painting the interior of the light box flat white? According to the additive process of color theory, a white surface reflects all colors of the visible spectrum equally (400nm-700nm, or visible RGB). Using a flat paint texture would even out the lamps reflectance by eliminating glare in areas of the chamber.

just my $.02

Yes I have.

I have been experimenting for the past couple months with flat black, flat white, polished copper and bright tin. The most difference seems to be between the flat black and the flat white. All work and all work well but IMHO have a different sound.

I'll try to use words to describe sound:

Regarding glare, I'm feeling certain that direct light (from filament to LDR) seems to be what creates the "warble" to the shifting sound, glare like from a shiny surface causes another point-source of light and depending on the LDR's the sound can be better, or worse. This maximum warble is like the Hendrix sound on Little Wing or Trower's Bridge Of Sighs (although that sound needs much reverb) 

With no direct light and no glare at all (just ambient reflection) and with the LDR's angled to avoid the direct light from the bulb element causes the smoothest phase shifting, is not the sound you want for Bridge Of Sighs, it's more like a swishy Gilmour sound like on "Time".

Makes me wonder if the original light cover was polished shiney or was just tin plated and sometimes not shiney, that could account for much of the sound differences.

Hope that makes some sence.

[rhdwave]

Interesting stuff Redhouse...

I think you're definately right as although my build isn't complete and i have many bugs to work out, right now i have the ldr's flat on the bottom and they get pretty much no direct light.  The surface of the light box is covered with aluminum foil.  Through all the noise and other problems i'm having i can detect the phasing sound and it's definately more shimmering then deep as far as i can tell.  Of course, there may be other reasons for this in my case, as i'm having other problems...but it may go a little way to confirming what you have said.

[alfafalfa]

I have come to the conclusion that after having experimented with the neovibe for a couple of months now the way the light hits the ldr's  is maybe the most important factor for its sound.
Redhouse you findings are very interesting and have been a great help to me.

What would be interesting is if some you guys could put up a soundclip of your vibes.
I will do this for mine, "Esnips" is what I use for this.
Then we have some reference.

I am going to listen to Hendix's Little Wing closely now.

Alf   

[alfafalfa]

Well here is an example of my Neovibe.
(Don't mind the playing too much)

Ibanez guitar 270 , singlecoil , 2  tube amps miked and a little reverb.

What I noticed is that if the speed is slower the light intensity goes down too and the effect is less noticeable. 
I f the speed goes up a bit it gets brighter and the effect is better and if it's too fast the lamp has no time to become dark so much less effect.

Did you notice this as well ?

http://www.esnips.com/doc/47cb4e48-7068-43ee-878b-190e4616b04c/neovibe-ex-2-mp3

Now completely dry:

http://www.esnips.com/doc/3fa35f71-b4ce-469a-b472-343cb5238641/neovibe-ex1

Alf

[rhdwave]

Alfalfa:

How do u have your ldrs set up? Are they flat on the bottom or are they facing the lamp and what kind of a light box are u using? If i had to guess from the sound i would say you have the ldrs facing the lamp at least slightly (not on the bottom facing up?)? Just wondering if my guess is correct...

[alfafalfa]

Hi rhdwave,

Yes they are facing the lamp like in reply # 24  above. They are not in the least  down on the bottom.
What should I do ?  Have you got any suggestions ? They would be most welcome !


Alf

[rhdwave]

Hi rhdwave,

Yes they are facing the lamp like in reply # 24  above. They are not in the least  down on the bottom.
What should I do ?  Have you got any suggestions ? They would be most welcome !


Alf

Alfalfa, i thought your clips sounded pretty good.  But if you want to change the sound and you have something in your head, i would see if Redhouse has any ideas.  He's been researching this for a while and has compiled different sounds for different positions of the ldrs.  I'm curious to hear everything he has to say about it as well.  Real good stuff.