Saturday, 3 March 2012

Mad Professor Sky Blue Overdrive

This is a modded version of the Sky Blue Overdrive, with a Tone control added, Texture control changed from an unnecessary dual to standard single 1K linear pot, and changes to the Z control to make it more useful.  1590B friendly if you can squeeze 5 pots in there.

Info about the original:

BJF design fine-tuned overdrive pedal

Hand-made in Finland premium quality overdrive pedal.

Mad Professor Sky Blue Overdrive (SBOD) is a very unique four knob pedal designed to overdrive already distorted amplifiers as well as provide light overdrive or soft distortion on clean sounds.
Special feature on this pedal is that you can adjust the feel and dynamics with Texture and Z knobs.

The Texture allows changing how and when circuit distorts as well as adjusting overall EQ.

The Z is a control that creates an adjustable load to the instrument connected to the SBOD input. With standard passive pickup loaded guitars dialing this control will adjust the upper resonant peak of the pickups. It also affects the taper of the volumecontrol on the guitar, adjusting how the tone cleans up when using the guitar volume knob.

Like all Mad Professor pedals SBOD is hand made in Finland using only premium components, to give years of trouble free operation with superb musical tone.


Controls

VOLUME:sets the output volume of the effect

DISTORT.: controls the distortion or overdrive effect

Z: is a control that creates an adjustable load to the instrument connected to the SBOD input. With standard guitars dialing this control will adjust the upper resonant peak of the pickups and also affect the taper of the volumecontrol on the guitar for easy setting of clean to distorted just from the volume control of guitar. This effect is masked if SBOD is driven by a buffered output such as from another guitar pedal or from active pickups

TEXTURE: allows changing how and when the circuit distorts as well as adjusting overall EQ. Dialing this control appears to adjust midrange, while it gives this impression from adjusting compression. Turning CCW gives more saturated effect that is easily distorted, turning CW gives a slight treble boost and less compression
(compression is used here to describe density of distortion since overall sound may be distorted throughout the dial)




9 comments:

  1. Hi Mark,
    This one seems to be an interesting one, though i will have to make some mods, as i don't have 2,5k pot but a 5k should do the job i guess. What is D3 1n400x? There is an input on the board, and below: input to Z2&Z3. Z2&Z3 should be connected the same row where input?
    If i don't manage to solve the problem with Mad Prof Delay i will send you pics, along with my finished projects. Now i start a TS808!
    Thanks for the great projects!

    ReplyDelete
    Replies
    1. You could use a 5K pot with a 5K resistor across the outer lugs, which will make it 2.5K. D3 is a reverse polarity protection diode, just use a 1N4001 or 1N5817 if you have them. And yes, just daisy chain from the input to Z2 and Z3, or take the input to Z3, Z2 to input on the board, and then put a link between Z2 and Z3.

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  2. An addict is an addict is an addict. Tag it.

    I had to reverse tone (lug 1 swapped with 3), 'cause i like it more as conventional tone control than "treble cut". These mods seem to be mainly that control, and since i didn't know what the mods were and how they were supposed to work, i swapped it. And used 5K1 between lugs 1 and 3 to make it more like 2K5(ish) pot.

    1N5817 went in for the polarity protection and i used two 3mm red LEDs back to back for clipping.

    Nice sounding OD in deed. Reminds me a lot of Zen/Mosferatu, but this feels a bit more open, maybe even more natural.

    I didn't have OP275s so i subbed it with OPA2134. Guess this is one of those circuits that benefit from audio amplifier instead of basic IC.

    Good thing i hoarded some of those 14K7s back in february. Will difinitely work as well with 15K :)
    +m

    ReplyDelete
    Replies
    1. Oh we're running through these unverified ones now! :o) Nice one mate, I'll reverse the Tone wiring too.

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    2. This is really worth a build. Relatively small and simple board that sounds really good.

      I might hit the sack early tonight, but i'll tackle the Fire Red tomorrow :)
      +m

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  3. http://mirosol.kapsi.fi/varasto/boxes/RedSunOD.jpg
    +m

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  4. Does your tone control have a drastic effect on the sound? I can't hear any change when rotating mine.. Was thinking of adding a tone control at the end of the circuit since it seems to have quite a bit volume.

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    Replies
    1. Just last week i dug my build out, and the tone control has a noticeable effect. Also i found out that higher gain settings lead to harsh oscillation, so i guess i'll need to check my build through...

      Jaskiainen? You from finland?
      +m

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  5. So is the above schematic correct and the tone control verified to work accordingly?

    ReplyDelete