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Hi there, welcome to my blog - La Revolution Deux. It's an odd name - but I like it! Here you will find all the info on my various DIY Guitar effects builds, amplifiers and guitars. Everything from a humble Ibanez tubescreamer to the holiest KLON Overdrive.

You may also find a few effects builds that I am looking to move on - usually in exchange for other effects/gear/cash. You can always check my ebay account to see what I've got up for grabs.

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Monday, 16 January 2012

Bigfoot FX - MagnaVibe

[Note - this is the newer Bigfoot Magnavibe, without the tremolo switch - Note]

Now here's an interesting one inspired by the great old Magnatone amps. I really like the sound of this thing from Bearfoot FX, here's their description (taken from the Bigfoot FX website):

"The Magnavibe was inspired by the early 1960's vibrato guitar effect (not the typical tremolo which is just pulse modulation). The Magnatone amp was known for having that amazing wobbly sound. Setting out to put that type of sound in a box and use it with any amp took much experimenting. The results are excellent. This is not a plain one dimensional vibrato such as a chorus pedal with the dry mix removed. Delay chips weren't even used back then. Nor is it just another uni-vibe clone, but a unique sound with that classic unique tone. Adding spring reverb or delay after the vibrato sounds especially good."

And a really nice soundclip of it in action (A cool cover of Etta James!): http://www.nicolacosta.com/at_last.mp3

Well KindaFuzzy over at the Freestompboxes forum bought one and took it apart and here's the results:


[Images pinched from KO Amps great Flickr album: http://www.flickr.com/photos/35422385@N07/]

Here's a schematic:


Nocentelli drew up a vero layout too:


As you can see by viewing the schematic it's pretty simple and it's *very* similar to Tim Escobedo's "Wobbletron" circuit as can be seen here (Basically the only real change is the use of a LED/LDR to modulate the vibrato instead of the JFET):

Anyhow, nevermind about that - it sounds nice, build one now :-)

Here's the freestompboxes.org topic discussing it's de-gooping!: http://freestompboxes.org/viewtopic.php?f=7&t=12539

[NOTE] If you want to build a slightly more complex version (But one that can achieve many more tones!) check out MadBeanPedals "QuadraVibe" project here - it's pretty cool : http://www.madbeanpedals.com/projects/index.html [NOTE]


7 comments:

  1. Why is the output resistance 1M5?

    It's so high!

    ReplyDelete
    Replies
    1. It's just a pull down resistor - it's job is to stop switching "pops".

      Delete
  2. by any chance would you know how to wire up a simple slow/fast switch like on the bigger version of the magnavibe? thanks

    ReplyDelete
    Replies
    1. Read up on "Phase Shift Oscillators", that's how the LFO on the Magnavibe is implemented - there are a few tricks to alter it's frequency range by altering cap and resistor values...

      Delete
  3. thank you very much!!

    ReplyDelete
  4. Thanks for the info on this pedal. The polarity of the three 1u capacitors are not marked on the vero diagram - am I right in thinking that the negative pole of one goes to the base of Q2, the negative pole of the next goes to the 10k resistor, and that the positive pole of the one on the right goes to the 1M5 resistor? Thanks.

    ReplyDelete
  5. How to LFO connection with the Main Photo circuit 4-6

    ReplyDelete

Comments are welcome on Revolution Deux. However, please do not spam links to unrelated sites - these comments will be removed! Thanks - Briggs.