Mad Professor Sky Blue Overdrive  [traced]

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Re: Mad Professor Sky Blue Overdrive

Postby Grendahl » 24 May 2010, 19:27

I haven't forgotten about it yet... that PCB is on my to-do list. We've had some illness around our house over the last two weeks so I haven't really had time to play with it yet. [smilie=rlp_smilie_207.gif]
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Re: Mad Professor Sky Blue Overdrive

Postby burstcracksplit » 24 May 2010, 19:40

I just had the same idea and changed the Z Pot to 1M and decreased C3 to 0.1uF. So far so good, at the moment I think it works much better for me. It's still not too bright. Thank's a lot ibodog2!!!
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Re: Mad Professor Sky Blue Overdrive

Postby Grendahl » 24 May 2010, 19:42

OK, working the A1M Z pot and 0.1uF C3 values into this PCB, as well as the single texture pot.
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Re: Mad Professor Sky Blue Overdrive

Postby Grendahl » 24 May 2010, 20:21

Before I start on the PCB, can you guys take a look at this to see if I've butchered it up please? :slap:

SBOD v1.2.png
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Re: Mad Professor Sky Blue Overdrive

Postby vot » 25 May 2010, 07:13

Simple tone control: instead of R12(1,8K) - B2K5 pot in series with 620R.
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Re: Mad Professor Sky Blue Overdrive

Postby Grendahl » 25 May 2010, 18:30

ibodog2 wrote:Check back in the thread for Mictester's modification for the single pot. You've got it hooked up wrong in the one you posted. Thanks!


Doh! You're right. I'll get that revised straight away.

In the meanwhile, I've pulled the prior image so as to not confuse anyone.
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Re: Mad Professor Sky Blue Overdrive

Postby Grendahl » 26 May 2010, 04:37

vot wrote:Simple tone control: instead of R12(1,8K) - B2K5 pot in series with 620R.


I haven't set this up on a breadboard yet, can anyone verify that the tone control mod works at the specified values? :scratch:

As a side note, had to go back and re-do the schematic again... Eagle died on me and the project file got corrupted. :evil: Grrr!

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Re: Mad Professor Sky Blue Overdrive

Postby mictester » 26 May 2010, 18:51

I've never really seen the point in loading down a pickup like this thing does - if you want top cut before the distortion stage, there are much better ways of doing it. This approach in this pedal also prevents you usefully putting anything before it - I sometimes like a clean booster, or a top end boost, or a compressor before I distort things.

The thing to like about this pedal is the distortion stage and the way the Texture control works (in the single pot version).

I've played around with this sort of approach before, and it's very controllable... It's also interesting to mix in some clean signal too, and be able to "cross-fade" between clean and distorted (a bit like the Sparkle Drive). Again, it can be done with a single pot, and if you dimension the output of the dirt stage to match the clean buffer, you can get a very smooth transition from one to the other. I have built one or two pedals into wah shells to do this - clean in the "heel" position to really distorted with the "toe" down. This allowed some really interesting effects...
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Re: Mad Professor Sky Blue Overdrive

Postby Grendahl » 27 May 2010, 04:24

That's great feedback, Mictester. Thank you!

I'm still pretty new to the DIY pedal scene, and while I can mix and match snippets, I'm not always able to anticipate the effect on the signal very well.

Per your suggestion, I think I'll pull the treble cut for now. Perhaps a dual box with a clean boost and tone controls would be a good pairing to this pedal as a second-in-line stompbox. What do you think?
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Re: Mad Professor Sky Blue Overdrive

Postby Lonkero » 29 May 2010, 14:30

Gotta build this :)

How big box is needed for that veroboard ?
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Re: Mad Professor Sky Blue Overdrive

Postby Lonkero » 29 May 2010, 15:36

That looks like Hammond 1590 box but slightly bigger. How you have secured that veroboard into the box?
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Re: Mad Professor Sky Blue Overdrive

Postby Lonkero » 31 May 2010, 01:25

What kind of red leds to use in diodes? Should they be 3mm, 5mm, extra bright or what?
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Re: Mad Professor Sky Blue Overdrive

Postby Lonkero » 31 May 2010, 07:25

ibodog2 wrote:
Lonkero wrote:What kind of red leds to use in diodes? Should they be 3mm, 5mm, extra bright or what?

Dude, go to the first page of this thread and read everything through and look at the photos...


Okay it seems normal 3mm red leds will do just fine :)
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Re: Mad Professor Sky Blue Overdrive

Postby Grendahl » 01 Jun 2010, 00:43

Ibodog2, did you ever get that presence issue sorted out?
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Re: Mad Professor Sky Blue Overdrive

Postby Lonkero » 01 Jun 2010, 15:10

Frank wrote:
burstcracksplit wrote:Thanks a lot for the tracing and the vero layout! I just build it and I like it, but I definitley think it needs more presence or a little bit more treble... hmm, decreasing C3 would be too simple, or what do you think?

I haven't been able to track it down exactly yet (and the original is due to go to a new owner soon). With the Z all the way down the original and copy have the same high frequency response to my ears. But the copy's Z at max is about the same response as the original at a little past noon. Maybe try a A1M pot for the Z instead of the A500K pot. I sent the Eagle schematic to another member here who was going to try do create a PCB. Maybe they'll be able to post that when it is finished. I'm still going on the theory that the difference in high frequency response is either a build issue on my part or a layout issue on my part. :lol: Or possibly a slight parts tolerance difference.


I want to build this but not yet sure if some info info comes regarding getting the Z control like in original.
The difference could well be caused by tolerance in pots. I tried with mine 250 projects 500k gain pots (20% tolerance) which one measured 510k, had definetely brighter sound than a pot which measured 480k. Did you measured the pot actual resistor values for the Z control both in clone and original?
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Re: Mad Professor Sky Blue Overdrive

Postby method » 13 Nov 2011, 21:37

Vero layout.

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Re: Mad Professor Sky Blue Overdrive

Postby RnFR » 13 Nov 2011, 21:56

why does this thing need a pulldown resistor? the Z pot does that!
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Re: Mad Professor Sky Blue Overdrive

Postby roseblood11 » 14 Nov 2011, 12:44

mictester wrote:I've never really seen the point in loading down a pickup like this thing does - if you want top cut before the distortion stage, there are much better ways of doing it. This approach in this pedal also prevents you usefully putting anything before it - I sometimes like a clean booster, or a top end boost, or a compressor before I distort things.


Sure, but is it just a top cut or does the Z-control influence the resonance frequency of the guitar?

@method: Great layout! Could you please post the *.diy file? Would be easier to draw some modifications then...
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Re: Mad Professor Sky Blue Overdrive

Postby audioguy » 16 Nov 2011, 00:04

Im getting a slight volume drop when I kick this in. Anyone else?
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Re: Mad Professor Sky Blue Overdrive

Postby medicament » 02 Sep 2012, 01:29

Hello. Maybe someone have layout for this schematic? Please upload this layout. thanks)))
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