Thursday, 28 March 2013

Pearl OD-5 Overdrive

Do not start building this one yet as it contains errors. Norwichbadger's amazing footwork on the comments will tell you how to fix yours, if you've built it already. I'll be fixing the layout or redrawing it at some point...

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Olav's relentless requesting took a few things before i got it done. First, he stated that he's happy with the PCB layout he found on the internet. :) And about four months. Told you it was going to be huge.

Transistor pins are once again made for modern everyday transistors like 2N3904, 2N5088 and so on. Original unit has 2SC2240s in it, so if you want to use those, just mind the pinout. Anyway. Here it is. Let's just hope it is correct. And happy easter for everyone!




29 comments:

  1. You.
    Have.
    Got.
    To.
    Be.
    Kidding.

    Thanks a million! Now let's see if I can verify it. I won't be disappointed if Geiri beats me to it though ;)
    Miro for president!

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  2. C'mon Miro, you keep mentioning huge boards, I thought this was going to be at least 40x40. :)

    My definition of "big" starts with Harold's Oberheim VCF v2 (30x20 or thereabouts) that I'm currently building, "huge" is at least a step above that. :)

    All joking aside, this is a bang up job. I've dabbled in vero design but I could never get anything to be even remotely compact. Big ups to you and Mark for all your layouts!


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    1. True. But the definition has other aspects too. First of all - the axial components used as axial. Second - the 1590B requirement. These couple layouts i've done recently are just on the fringe of fitting in to 1590B. Should be doable, but will take some more measuring than usual. This is closer to my definition of huge. Massive would be a board that needs BB box :)

      Harald Sabro does really good work. However, i don't think my and Mark's work can be compared to his. Granted, we all draw stripboard layouts :) We just have different philosophies about it. I'm quite happy about how i'm doing it :)
      +m

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  3. Checking to see if I have all the required parts. Just about. Ordering reverse log dual gang pots and a handful of transistors. Happy Easter Miro!

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    1. You should get a bunch if you haven't built a Klon yet :D
      +m

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    2. I did. Haven't built the KLON yet but have all the parts gathered in a baggie. I do that for any project I'm planning to build. Ordering isn't the point usually. It's finding the time to solder all them pesky lil' parts to that stripboard.

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  4. holy moley, you've been doing some big boards lately. I fully condone this activity, as hopefully it will lead to a Boss HM2 layout. :D

    4 ICs, 6 transistors and 12+ diodes? yea....no problem.

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    1. I'd like to see some Lovetones or at least Moogerfoogers...

      Any takers? :)

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    2. Moogerfoogers

      http://www.gearslutz.com/board/attachments/geekslutz-forum/267799d1324110826-gutz-moog_mf-gutz.jpg

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    3. HM2 has been on my want list for quite some time. I want one for myself as i couldn't find reasonably priced original anywhere and one friend who has one, won't sell it. One other friend sold his in '99 or so. He used it with a bass in a hardcore band back then - i would mod one for bass too...

      The schem is huge and there is not much i could snip without affecting the operation or sound.

      I know i'm going to eye that schematic from time to time, just to see if i would be up to the task...

      if i end up drawing it, i bet you guys a tenner that in the first 5 comments there's a request for MT2 :D
      +m

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    4. Goran: Those. Won't happen. :)
      +m

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    5. I think you should have typed that in capital letters, and maybe a larger font :o)

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    6. @mirosol, I've been a fan of Entombed for far, far too long and have been hunting that tone since the early 90's. I can't see that layout working on stripboard though. It's just so giant. One of these days I'll just shut up and buy the Behringer one, as the BOSS is getting harder and harder to find. I wanted to have a hand-wired one for my own edification.
      Yea, the MT2 requests will be hot on the heels of the HM2, for sure.

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    7. Have you thought about rehousing a Behringer? BB box, alpha pots and true bypass. 20€ for a Behringer box and ~15€ for the rehouse parts. Should be better than original. Only hard thing is doing the bypass, as those have mostly SMD components. Not impossible, but harder to do. Circuits are 1:1 with a discontinued Boss'...
      +m

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    8. I'll do the HM2. I just had a proper look and the active EQ is pretty simple with minimal surrounding components and the central opamp channel in the signal path is a simple buffer, so you could use a quad and a dual with very few links, and they may even fit next to each other in a 21 column wide board (it'll be tight, but maybe). I also reckon I could get the JFET/BJT stages in one 21 column run and so it may end up smaller than even I'm expecting. Worse case scenario and it would be pretty easy to get that in my Klon layout size board and so it still would in theory fit in a 1590B, best case scenario I think you could potentially do it with around 20 rows.

      It will be a few weeks at least because I have a lot on and don't expect to do very many "normal" size layouts during that time, but it'll be the first larger one I do when I'm back to normal work-wise.

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    9. @mirosol, I've thought about either just dealing with the turd Behringer box, or rehousing it in a DD with a dirt pedal and maybe a compressor circuit in front of it.
      @IvIark, I'll be eagerly waiting!

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    10. That would be super. Scary ones tend to become less scary when eyed often enough :)

      Funny, but 20 vs. 21 really makes a difference..
      +m

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    11. Jon: How about Behringer metalzone-clone and OC-3-clone in one big box? :D
      +m

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    12. yikes, that'd be a screamer!
      I'm a devotee of the HM2 though. The swedish buzzsaw sound just doesn't sound the same through a metalzone. The buzzsaw needs a dirt pedal into an HM2 with the volume/EQs maxed, a'la Daniel Ekeroth's vid.
      http://www.youtube.com/watch?v=b-1vcuKcXeI
      to quote; "ent you need to hev eh Boss Heveymetel pedel, n don't try this wiv eh MetelSone pedel, because Metelsone pedels, they yus SOCK"
      (no insult intended to the nordic members of the board, but I get a huge kick out of the accent)

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    13. That is a classic clip. I remember seeing it first years ago :)
      +m

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  5. Couldn't you just make it 'always on' and use a 3pdt to A/B with bypass? Saves on a lot of nervousness poking around in those tiny components.

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    1. Basically yes. But making it always on would still need some poking. Let's just say that i'm not in love with electronic switching :)

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  6. Does not work! Anyone else having problems?

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  7. Still haven't had a chance to start working on this.

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  8. PEARL OD-5 Overdrive.
    Miro suggested this to me as a non-working challenge. It has been one!
    There are several problems with it. The most important are that the main smoothing capacitor (220uf) and the VB capacitor 47uf are shown the wrong way around! I only noticed this when I wired my Red +9v wire to 1/23! Having fixed that I fired it up and got a moderately distorted output but the only controls that did anything were the Level control and the Freq which didn't change the tone but gave a feedback tone increasing in frequency clockwise. I then had another look at the schematic! The reason for the behaviour is probably that OP2 Out (IC1A pin 1) is not connected to OP3 inv (IC1B -pin 6) via C8 (100nf) and R17 (10k) (both missing). The tone control did not work properly because its miswired and Eq gain3 should be attached to OP3 output (IC1B pin7) but at the moment it's not connected at all. The signal I was getting probably came mainly from Q2 via C5 (1uf) and R16 (10k) directly to OP3 inv. I also noticed that the 220nf/1K to earth from OP4 Inv (IC1A pin 2) is missing.

    I bodged the board as follows:-
    I added C8 (100nf) and r17(10k) from Col 10 / row 19 to Col20 / row 5.
    I added c11 (200nf) and R28 (1k)from col9/ row 4 to col 9 /row 6.
    I connected Eq gain 3 to col20 / row 4.
    I rewired the frequency as follows (existing to new) 2-1 to 2-3, 1-3 to 1-2, 1-2 & 2-2 to 1-3 & 2-2.

    All the controls have an effect now and its an OK overdrive but its nothing special in my opinion. The Freq works a bit like a cockable wah depending on the setting of eq gain.
    The tone is a bit tizzy so I added a 47pf between col7/row3 and row4 and that helps a bit.

    I didn't use a zener diode but replaced D4 with a 3k3 resistor.
    If this layout does get reworked I won't build it again. There are too many components on too big a board for what it does.


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    1. You're the Man!

      You can probably guess how much i value posts like the one above in comparison to "doesn't work" or "i'd like to request..."

      I guess i should redraw the whole thing... I'm putting it on hold for now and we'll see when i have time or inspiration to fix or redraw it.

      I do like the original. It has some qualities that separates it from TS-masses...

      One more time. Huge thank yous to you sir!
      +m

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    2. Thanks for your kind comments and for your great layouts.
      I suppose I was a little harsh about the circuit. That psuedo-parametric freq control is a cut above the average.

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  9. Can we get the ball rolling on this one again?

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