Saturday, 4 February 2012

Prescription Electronics Clean Octave Blend

In the words of Prescription Electronics, the COB: "allows its user to blend a clean guitar signal with a pure upper octave at the preferred balance including output and overdrive levels.  Noise free and compatible with your favorite stompboxes!"



25 comments:

  1. This one here is a hard call, since there is no sample clips about it around to compare it to.. But i think i can call it.

    It's neither a fuzz, nor a digital synth style super clean ring modulation / octave up, but it's clean enough to call it an octaver. 1M for octave pot seems to be a bit too much - and it should be wired the other way around. One can just cut the link between lugs 3 and 2 - and solder a new one between 1 and 2. If i box this, i'll probably swap that pot for 500K or maybe even smaller..

    One other thing is that i got it to go a bit less fuzzier with 2N5089s. So as always, the sockets and the trial/error may be the best option to find what works the best. Just be sure to check out the pinouts :)

    Might be much better effect with/for bass.

    Anyway. The layout works. Mark. Congratulations! You're THE MAN. No one else on the planet has drawn 200 verified guitar effect layouts for tagboard and vero! I thank you from the bottom of my heart. Your layouts and advice here on the blog have taught me a lot and i really appreciate it. Thank you. And keep 'em coming - I'll be building!
    +m

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    Replies
    1. Top man, I'll do the corrections and tag it. 200th post coming! :o)

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  2. Just finished making this - fired up first time! I'm looking for subtle textural effects and this is really good for that.

    Use this into a clean amp with the fuzz and the octave just there, add the right kind of reverb and echo, and you really notice if you switch it off.

    Our band will use this in the quieter/dramatic moments.

    Thanks Mark. Three quarters of our main guitar pedalboard is full of the goodies from this site.

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  3. I took Mirosol's advice and tried 5089's.

    They work better but while I had the two types of transistors together I tried combinations of the two. I ended up with Q3 standard, and the rest 5089.

    For subtle textural use, (much clean signal) this it is the right kind of fizz in the fuzz to layer the octave effect under the clean signal like a keyboard comb filter sound.

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  4. There are a couple of YouTube demos, this thing actually sounds pretty good.

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  5. Just built it, altho I used nte123a's (that's all I had laying around). They don't work so good in it :-)
    Gonna try again with 5089s today. Thank god for transistor sockets, right?

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  6. Just built it, altho I used nte123a's (that's all I had laying around). They don't work so good in it :-)
    Gonna try again with 5089s today. Thank god for transistor sockets, right?

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  7. which are the best values ​​for the potentiometer then the octave? 500k?

    which are the best, the 2N5089 or 2N3904 transistors?


    thank you very much my friends

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  8. In the scheme, appears resistance 4k7 from emitter of q4 to ground.????

    Great blog (like a dream)!!!!

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    Replies
    1. Yes you're right, thanks for the heads up. If you move the top left hand 10u cap one column to the left then the 4K7 can go in that gap. I'll make the correction now.

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    2. Yea, this little 4k7 change sound, more octave just like demo!!!
      I'm just soldered on jumper to ground
      And no needs modify vero.
      Sorry for my English :-*

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  9. In the same box, this circuit with robot devil in parallel (clean inputs in two effects and mixing signal in output jack) it's great!!! (believe me, not noise box, very usable)

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  10. Hey,

    I followed this layout to the letter and, while I have sound - volume controls and what seems to be the blend, I get no octave at all. I'm using 3904s as well. Any ideas?

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    Replies
    1. And then the glitch makes itself known. Forgot to add the left ground from the board and switch the lugs on the octave pot. AMAZING SOUND!

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  11. I built this one the other day. it sounds awesome. just waiting til Monday when the enclosure arrives to box it up. thanks for posting it.

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  12. I got it completed today. I really dig this one.
    pics:

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/COB/COB-01.jpg

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/COB/COB-02.jpg

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  13. i am confused about q1, q2, q3 and q4 on the layout, why we see cbe and ebc if they are the same and positioned the same way?

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    Replies
    1. Just follow the pinout for the 2N3904. Q3 and Q4 are positioned the opposite way round to Q1/Q2 despite the way they look in the layout.

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  14. I'm having some trouble getting any upper octave at all.

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    Replies
    1. I should add that I have swapped the 1M pot for a 250k Lin and still no better.

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  15. I found the problem with my build. I had the 4k7 resistor from Q4 connected to the base instead of the emitter. I move both it and the diode down one row, I now have the upper octave. It was a tight squeeze getting it into a 1590b along with a battery. I'm gonna box this up properly without the space for a battery. Nice sounding pedal.

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  16. Could this be used to make a shimmer reverb, with the reverb full wet in a parallel loop?

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  17. Checked some youtube demos, seems like a nice pedal. I'm thinking of building an ultimate fuzzbox based on a fuzz face. Might be worth thinking about pairing it up with this. Dedicated switches for both. That would be awesome.

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  18. Hi, could someone share schematic for COB.. I cannot find it anymore :/

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  19. Hello, I have built it today. I work with amplitube, my guitar direct in this COB, and i doesn't have any octave. Volume work, blend too, but octave doesn't work. I've checked all my build, and no mistake...

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