Another "vibe" thread: led vs photocell

Discussion in 'The Stomp Box' started by steam-powered, Feb 21, 2015.

  1. steam-powered

    steam-powered Tele-Meister

    Posts:
    477
    Joined:
    Jan 6, 2013
    Location:
    USA
    I'm ignorant regarding the "innards" of pedals and trying to figure something out regarding vibe pedals.

    Over the past several years I've owned several vibe pedals and all but one has either been returned or sold due to rf issues in my neighborhood (same with fuzz-face and treble booster pedals). From what I've read online, Jimi Hendrix also experienced radio interference at least once when using his univibe, but I couldn't figure out why a univibe would have such problems, and I've never met anybody who experienced such issues with their vibes.

    After buying a couple Black Cat Pedals, I noticed that they made a "high-end" vibe pedal but, instead of using an led for the "on/off" light, they opted to use a photocell. I'm not a wealthy man, and the Black Cat Vibe wasn't exactly inexpensive, but I took a chance and purchased one. It's been several weeks now, using it almost every day, and much to my delight: no rf issues!!!

    Question: does the Black Cat Vibe's use of a photocell, rather than an LED, account for the lack of radio interference? I've tried Fulltone, Foxrox Aqua-vibe, DLS Versa Vibe, and experienced radio noise. I'm assuming they're all very similar regarding components and design, so I'm wondering if the LED was the problem. Thoughts?
     
  2. ICTRock

    ICTRock Tele-Afflicted

    Posts:
    1,518
    Joined:
    Jul 31, 2014
    Location:
    Tampa,FL
    um ... no. univibes are all going to use photocells/ldrs and lamps/LEDs

    without looking at schema, any noise issues or solutions would have more to do with shunting, shielding, or grounding
     
  3. steam-powered

    steam-powered Tele-Meister

    Posts:
    477
    Joined:
    Jan 6, 2013
    Location:
    USA
    So using a lamp, rather than an led, for the "on/off" light shouldn't make any difference regarding radio noise? I'm using the same cables, guitars, amp, etc, and can't figure out why my current vibe doesn't have the rf issues as other's I've tried. About a week ago I did a side-by-side with a Fulltone and only the Fulltone had AM radio problems. :confused:
     
  4. ICTRock

    ICTRock Tele-Afflicted

    Posts:
    1,518
    Joined:
    Jul 31, 2014
    Location:
    Tampa,FL
    looking at pics of the guts of that pedal and it uses a lamp and 4 photocells like most other univibes.
     
  5. steam-powered

    steam-powered Tele-Meister

    Posts:
    477
    Joined:
    Jan 6, 2013
    Location:
    USA
    I forgot to mention: I had the same problem with phaser pedals awhile back, couldn't record due to radio signals, with the exception of the MXR vintage 90, which didn't have an led indicator. I'd assumed then, too, that it might have something to do with an led. Hmmmm, I'm really wondering why some would pick up radio signals and others don't, if it's not the led.
     
  6. JD0x0

    JD0x0 Poster Extraordinaire

    Age:
    30
    Posts:
    5,915
    Joined:
    Feb 22, 2009
    Location:
    New York
    My guess would be cheap(er) components versus high(er) quality ones. Cheap, noisy components and poor shielding would create a higher noise floor and would have a higher potential to be affected by interference.
     
  7. steam-powered

    steam-powered Tele-Meister

    Posts:
    477
    Joined:
    Jan 6, 2013
    Location:
    USA
    That could account for it, but the Foxrox and DLS are considered "higher-end" pedals and probably use quality components.
     
  8. RyanJH

    RyanJH Tele-Meister

    Posts:
    114
    Joined:
    Jan 26, 2013
    There could be a number of reasons.

    I'm not sure what material Black Cat uses for their "custom made enclosures", but if it isn't aluminum, that could be a factor. Aluminum isn't very good for shielding from RF. Most manufacturers don't care because aluminum enclosures are cheap and easy to machine.

    There's also power supply filtering. Some manufacturers use better filtering on the power rail than others.

    Shielded wire on the input and output wires inside the pedal can cut down on RF getting into your signal. Most manufacturers use unshielded hookup wire for this.

    Just some possibilities.

    -Ryan
     
  9. steam-powered

    steam-powered Tele-Meister

    Posts:
    477
    Joined:
    Jan 6, 2013
    Location:
    USA
    Thanks for the feedback. For some reason, when I find something that works with my rig, I want to know the "why" it works.
     
  10. 1300 E Valencia

    1300 E Valencia Friend of Leo's

    Posts:
    2,574
    Joined:
    Dec 13, 2010
    Location:
    Fullerton CA
    To be clear, the photocell is part of the inner workings of a vibe pedal. It's not used for the ON/OFF indicator. That's almost certainly an LED, at least on a modern pedal.
     
  11. RyanJH

    RyanJH Tele-Meister

    Posts:
    114
    Joined:
    Jan 26, 2013
    Exactly. A photocell is also called an LDR or a Light Dependent Resistor. An LED (or LED's) is positioned in front of it, and the flashing of the LED (controlled in some form by the speed and depth controls) varies the resistance of the LDR. An LDR doesn't give off any light of it's own.

    -Ryan
     
  12. Iago

    Iago Friend of Leo's

    Posts:
    2,069
    Joined:
    Sep 18, 2006
    Location:
    Brazil

    I think the OP is talking about photocell (mini-lamp) operated vibes X LED operated Vibes.

    One thing I can tell is that being photocell or LED-based is not making a difference here because all those pedals you mentioned as being noisy have the photocell + LDR's. That's the classic univibe design.

    Many other things can be influencing the radio noise. IME, better grounding techniques and appropriate transistors (just a guess in the last case, at least in my Fuzz Face I cured RF by swapping transistors) may cure that. May.

    LED-based "vibes" as the Dunlop Rotovibe, Moen "Shaky Jimi" and the DIY classic, the John Hollis "Easyvibe" use LED's instead of the mini-lamp (photocell). I have a Shaky Jimi and it doesn't pick up RF, but that's just my experience.
     
  13. RyanJH

    RyanJH Tele-Meister

    Posts:
    114
    Joined:
    Jan 26, 2013
    Why are you calling photocells "mini-lamps", and why are you using the terms LDR and Photocell as if they're different things? A photocell doesn't produce light; it isn't a lamp. It's an LDR, a Light Dependent Resistor. The less light it sees, the higher the resistance.

    The Univibe itself is just a phaser with an asymmetrical sweep. The photocells (LDRs) and LED/light bulb control this sweep. The original Univibe has 4 photocells in it.

    Some "Vibe" pedals use other means to control the sweep, but at heart the Univibe is just a glorified phaser.

    -Ryan
     
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.