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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.

Have fun, enjoy the blog - Fred Briggs :-)


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Thursday, 19 January 2012

Death by Audio - Robot

More Death by Audio, this time it's the Robot pitch shifter. My description? It's crazy. Words cannot explain this thing, just have a listen to it (more ProGuitarShop, are there any pedals these guys haven't had?):

Here's the description from the Death by Audio website:

"The Robot is a low fidelity 8 bit pitch transposer with absolutely no feelings what-so-ever. It is completely synthetic and transforms any input into a spuree of resynthesized robot jargon.

THE CONTROL KNOB: The control knob is located on the right hand side of the pedal. The knob controls the pitch of the effect in NORMAL, OCTAVE DOWN, and OCTAVE UP modes. When in ARPEGGIATOR mode it adjusts the speed of the arpeggiation.


NORMAL: Same pitch with 8 bit digital conversion with the CONTROL KNOB fully clockwise. Turning the CONTROL KNOB down bends the pitch down.
OCTAVE DOWN: The CONTROL KNOB turned fully clockwise yields a nasty octave down sound. Turning the CONTROL KNOB down bends the pitch further down.
OCTAVE UP: The CONTROL KNOB turned fully clockwise yields a nasty octave up sound. Turning the CONTROL KNOB down bends the pitch down.
ARPEGGIATOR: The pitch arpeggiates in a sequence. The CONTROL KNOB adjusts the speed of the arpeggiation."

Here's a PCB picture provided by Glass_Hero:

And he's drawn the schematic up too (excellent work!):

Now, you need to know how to wire up that rotary switch to switch between the modes. The Death by Audio guys have used a 4P3T rotary switch to allow you to select normal "robot" mod, octave up, octave down and arpeg mode. I'd wire in three spst which switch chip pins 1,2 and 3 (SW0-SW2) to ground. Then you can select different modes independently with much more range.

To really understand the HT8950 switching check out it's datasheet: http://www.mediafire.com/?3cq894a5ynbn7pl, that's got the switching table in it which will allow you to select exactly what modes you want.

Here's the freestompboxes.org forum thread for reference:  http://freestompboxes.org/viewtopic.php?f=7&t=12112


  1. oh lord...the build list just got bigger!!!

  2. Isn't that supposed to be a 4 position rotary switch a.k.a. 3P4T? On the picture of the PCB, I see 3 center poles in a triangle formation and 4 throw positions in the video demonstration. I guess that 3 of the throws go to ground and the 4th throw is not connected to ground?

  3. I think the V- on the schematic is actually ground, and the bits labeled as ground are actually VB

  4. Also would be nice to see the underside of that’s PCB to learn a little more about that spot labeled “overload”


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