Univibe/Neovibe circuit insights

[R.G.]

What I was trying to say is that the LED has a narrow voltage range in which it goes on and off.  What about the light radiated as a function of current, voltage? Maybe LEDs are less or more linear than a bulb, I do not know, but IMHO the bulb is more realistic at low speeds. The LED/LDR-P90 LFO or FET/P90 LFO seem to stay in the "sine wave" tops for a while, that is, like taking a rest without an audible change of phase. At least, this is the difference between my P90 and my vibe clone; could be just my "experience"

Ah, I understand.

LEDs have a light output that is almost linear with current; the voltage changes very little from min to max current. In theory, you would want to drive an LED with a sine wave of current. In practice, it's usually good enough to drive it through a resistor. To the extent that the voltage across resistor+LED is bigger than just the voltage across the LED, the resistor makes the current follow the voltage. Not perfect, but often OK.

Incandescent bulbs have a light output that varies in both intensity and color as a modestly complicated function of the power (V*I) in the filament. So bulbs are much less linear with either the applied voltage or current than LEDs.

But then LDRs are nonlinear with respect to resistance per amount of light received too.

Finally, sine waves do have a part of the top and bottom where they don't change much - it's part of what we hear as "rotary sounding". It's the triangles that reverse instantly that sound odd to me.

[mike_a]

But there are sine oscillators using opamps.
They have a bit more parts than their triangle counterparts, but not that much more.

It is also possible to approximate a sine wave using a triangle wave with clipping diodes.
It won't give a perfect sine, but I highly doubt that anyone can hear the difference.

I dont see the point of this argument though. The design works well and people want vibes because they sound like vibes. Everything about them is what makes them sound unique and why they are just more organic than a vanilla phase 90.

There's no need to get touchy about this... 
I wasn't arguing, but rather just sharing some thoughts of mine regarding ideas for improvements.

Some might not view these things as improvements - that is their right.
I would think that using less parts, and more importantly - less exotic parts (I for one have difficulties getting dual pots where I live), would be considered as an improvement.

What was I thinking...

[Nitefly182]

Sorry RG, I was not clear.
I am aware of the effect of temp as a function of current. Anyway, thanks.

What I was trying to say is that the LED has a narrow voltage range in which it goes on and off.  What about the light radiated as a function of current, voltage? Maybe LEDs are less or more linear than a bulb, I do not know, but IMHO the bulb is more realistic at low speeds. The LED/LDR-P90 LFO or FET/P90 LFO seem to stay in the "sine wave" tops for a while, that is, like taking a rest without an audible change of phase. At least, this is the difference between my P90 and my vibe clone; could be just my "experience"

I dont see the point of this argument though. The design works well and people want vibes because they sound like vibes.

... or peolple like the vibe because Jimi liked it?

IIRC russians say: if something works ok then do not change it.
I agree that the vibe should be left as is.
But for educational purposes talking about the flaws of the vibe, and how to improve it, although in theory, is a good thing.

mac

I dont really listen to hendrix or classic rock so his use of the effect never had much bearing on my appreciation for the sound of a good vibe.  I agree that looking at effects and seeing better ways to do things can be good but changing any part of an audio design usually changes the sound which can end poorly.                                   

[mac]

RG, muchas gracias.

mac

[puretube]

Some "Vibelight" musings:
Wilder, 1964
Chase/Plunkett, 1972

[R.G.]

It's one of the scourges of my life that I keep inventing things - too late!

This is going to sound a bit stuffy, but I did invent  a form of the Univibe phase stage in my last undergraduate year of college, 1973. It worked, to the limited extent that my construction capabilities would fab it.

That's completely beside the fact that commercial univibes were already on the market and the patents you mention were yet years earlier than that. 

I seem to always be pounding up the hill to discover... yet another hill. 

But I did invent the flying lawn mower years before the Flymo came to market. 

[DougH]

I was running some errands with my son Saturday and we saw a road crew mowing the lawn on a steep grade on the side of a highway overpass with a robot lawn mower. Now *that* was pretty cool... I know those have been around but it's the first I've seen one.

Kind of was a dream of mine when I was 11 or 12...

Oh, and obligatory vibe comment: I have an Easyvibe pcb I'll eventually build. Until then I'm pretty satisfied with the "vibey" sound I get with my Phase 100. "Wobbly" LFO and LDR's may have something to do with it.