Sunday, 30 August 2015

Selmer Buzztone



Here's one for Syd Barrett era Pink Floyd fans. This is the pedal Syd used on tracks like "Interstellar Overdrive". It's more like a buzzy overdrive than a typical fuzz pedal.

I will probably build this with .15" pitch stripboard but you can use .1" pitch as well. The bottom strip is for mounting the board on standoffs but if you're not using standoffs you can cut that row off.

This pedal is normally powered off a pair of AA batteries for the -3V. For daisy chaining you could use the inverter + regulator daughter board that Mark posted with his Maestro FZ-1 layout



Here's the layout with the requested switchable gain boost mod




the requested layout with inverter and regulator onboard. This is unverified


46 comments:

  1. Hey this looks great! Thanks Travis!
    Any thoughts on transistor HFE and Leakage?

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  2. Thanks. I saw a schematic that indicated the hfe was something like

    Q1: ~80hfe Q2: ~120hfe Q3: ~80 hfe

    I would just try starting with anything in that ballpark hfe with moderate leakage and audition different stuff from there

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    1. Neat thats pretty much the same as a tonebender. 80 80 120.

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  3. I am having a hard time finding 80hfe or so in my PNP germaniums...
    Can I use NPN instead? Do I only need to switch the pins to do so?

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    1. Flip the transistors (mind the pinout), swap the -9v and +GND, and flip all electro caps.

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    2. I will find another solution then, because I wanted to have 2 PNPs and one NPN...
      I'll try to source some HFE correct PNP Ge...

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    3. I would try what you have first and see how it sounds. I've made them with Q1 and Q3 silicone and Q2 Ge. There are some DIYstopboxes threads on it. I've just gotten into measure Ge and all that so i don't know what' ive droped in before, but it seemed forgiving to dropping random stuff in there.

      On good mod (DIYstompboxes) it to add a 22uf cap to ground on the Q1 emitter in parallel with the 1K resistor, livens it up. good for a switch

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  4. I'll post another layout with the switchable cap on Q1 emitter later. Thanks for your input

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  5. Sorry Travis, but I have to mention this again, and just know that: I really appreciate your efforts and contributions, but there is one tiny little detail that is annoying the hell out of me:

    COULD YOU PLEASE GIVE YOUR PICTURE-FILES A LOGICAL AND DESCRIPTIVE NAME.
    Not automaticly generated names like the one for this picture-file: "62461726-5954-4377-95a9-70e86e7cca2e_zpskux76ki4"

    Like most others, I use drag and drop, in order to save the picture files to my laptop (and not the long tedious right-click, save as... and so on...).
    I just grab the picture and chuck it in my chosen (offline) Library folder with the rest of the layouts I´ve collected.
    And I actually expect to be able to find it easily a couple of days afterwards by name, just by scrolling alphabetically trough the list of files...
    But this is not the case with your files, and I easily waste an extra 10 minutes just searching for that damn file, and by the time I find it, my mood as totally changed beacause of that tiny annoyance! NOT GOOD!

    In other words: your rutine (or lack of routine) is generating extra (and annoying) activity in our end, that has not been present on this site before!!!
    I would be very happy, if you could pay serious attention to this tiny, but very far-reaching annoyance/issue!
    I guarrantee you, that there are many more who has been a bit annoyed by this as well, but who decide not to mention it, being afraid to come across picky, grumpy or rude.
    I´m not one of those people!

    KNOW THIS:
    Your layouts looks very good and are well layed out, so "misunderstand me correctly" here...
    Your work is greatly appreaciated!!!

    ...and as for the pedal, it sounds great on the demo!
    Just like my Selmer Treble & Bass MK-III amp at full blast!
    They really seemed to have nailed it. Top of my future build list!

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  6. I will re upload the files with normal names once I figure out a way to log on with my laptop so I can upload them directly instead of using photobucket. Right now I'm unable to log on to the site with my laptop, and I can't control the name of the file the way I'm uploading images

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  7. Requested modified layout has been added

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    1. Awesome, thanks! this is the first circuit i laid out on stripboard, and i keep using my original one, that has many doubled up holes, standing resistors and all sorts of bad stuff. Nice to have a comfortable layout.

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  8. Cool, I hope the layout helps :)

    Let me know if you build this successfully as it's currently unverified

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  9. Sounds neat. I may have to try and find a source for some more Ge's..
    The bottom strip that is empty, with those 2 holes isn't for anything, right? Just never seen that before.
    Thanks for the contribution Travis.

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  10. The bottom strip is there for mounting the board on standoffs. You can just cut that row off if you don't want to mount the board that way

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  11. Can anyone point me in the right direction for the germanium transistors, preferably UK/Europe but not essential.
    Also if you know a good fair priced place for all germanium transistors in general.

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    1. Are you looking for tested sets or untested lots? I'm an American so I only really know of smallbear for the tested sets. I buy untested lots off eBay

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    2. Checked small bear and they don't have the 2N2613.
      ebay have one unit for £17 ($27) which although im not sure sounds expensive.
      Does anyone have any further suggestions, are there alternative transistors that will perform the same?
      Any help would be great.
      Thanks in advance,
      Matt

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    3. Find a transistor with a similar hfe/leakage range to the one you're after, then buy it for a reasonable price. The sound is more in the circuit than any other overpriced mojo a lot of the time. $27 for one transistor is insanity.

      Look through this discussion board:

      http://www.diystompboxes.com/smfforum/index.php?topic=95208.0

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    4. Do you have a transistor tester that can measure hfe and leakage? If so there are a lot of different PNP Ge transistors available on eBay that you could try. AC125, AC128, 2SB175 are some common types you might try.

      If you need a tested set then the Maestro FZ-1A (or maybe called "fuzz a tort") set from smallbear should work

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  12. Verified. I haven't tried the switchable gain boost version yet but i'm sure that will work fine. I upped the 1k q2 collector resister to 1.5k for a little more grit but i'm thinking I might do a silicon version to try and obtain something a little hairier! I stacked it with an Echorec and then got straight into Piper At The Gates. In fact I was wearing a big demented grin. I'd also like to take the time to welcome everyone back, thank lvlark, Mirosol for their patience and guidance and wish Travis, Javi, Zach and Alex all the best.

    Thanks,
    Phil.

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  13. Thanks for verifying P.Gofton, hope you enjoy.

    So one big question. Is that an original Echorec or the Catalinbread?

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    1. Bone stock original...Catalinbread...unfortunately i've never clapped eyes upon an original let alone play one. The Catalinbread is great though, so many variables. BTW, any idea what people should shoot for in regards to bias voltages?

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  14. It works. I only tested it so far with silicon 2n2907. Sounded pretty good actually. The blend doesn't work right with silicon tho.

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  15. I did the switchable gain version. Sorry guys this is my 1st time using this bloggin stuff or whatever it's called. Ha

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  16. Nice job thanks Gregory. The depth control isn't supposed to work like a blend. It's a variable resistor between the first and second gain stages which works as a gain control

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  17. Sorry bout that I meant gain. I made a replica mxr blue box with the two 741s today. And got the blend on that confused with the gain on this. Anyways the gain feels much better with germanium. And all the gain combos seem to work fairly well. I'll try a bunch of combinations. Feels like the gain is a little bunched at the end of the taper tho. I'll try some different tapers

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  18. I've made a few with silicon (2N2222's or other lower gain) in Q1 and Q3 and germanium in Q2, bias to like 0.7volts or so with the Q2 collector resistor. i've been adding a germanium diode to the Q2 (base to emitter?) to help prevent the temperature thing with germanium. one of the first ones i made without it, guy said it sounded like someone was slowly turning a tone knob on stage! Anyway, i'm more of a builder than guitar player, but this is a great fuzz.

    This was my first ever single pedal build a few years ago, put it in an oversize octo box (like a fuzz face). Now I put everything in the octo boxes, lots of wasted space!

    http://www.madbeanpedals.com/forum/index.php?topic=16488.msg156427

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  19. Hi, I measured something like 100 transistor with the germanium transistor tester (which thanks to Iviark I built myself). except for the few 2sa12s which were mostly very low leakage with hfe around 30,nearly all of them were of hfe's 150 to 250. it seems that the usable ones most have moderate leakage with hfe's around 50 to 150. am I right? do you think there is something wrong with my measurement. by the way the trannies were Gc301, 2sb75, 2sb54, 2sb175, 2sb176 and 2sa12.
    thanks a lot.

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  20. ooops! sorry, "Ivlark", also 100 "transistors"," must " anything else?!

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  21. I Know this is perhaps a tall order so excuse my cheek, but would it be possible to make a scematic (one board only layout) that uses a 9v power supply? I know there is the daughterboard option but I have less luck the more things that are floating about inside a pedal and was just about to opt for the battery enclosure route -then realised how much more room that will take up....
    If you could it would make my day

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  22. Sure I can do that. Check back soon and I'll have it done

    In the meantime, order some 78L33 voltage regulators!

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  23. Thanks Travis you are a star!
    I have some L78L33 regulators already which I think are the same things.
    Again Thanks to the highest.

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  24. Hi Travis, Any joy with the 9v Power supply mod?

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    Replies
    1. hey Mattfode, October wasn't too great for me and I forgot all about this request. sorry for the delay, the new layout is now up

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  25. Hi, I got a problem everything works ok when i stay in the first half of the gain pot, on the second half I got self oscillation and its frenquency lowers as I push the gain, does someone got an idea? I alreday triple cheched everything I believe, but....?

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  26. This comment has been removed by the author.

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  27. Do the Transistors need to be leaky like the FZ-1 or can you get away with transistor that have very little leakage?

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  28. I can't say for sure since I haven't built this yet but I encourage you to experiment with whatever you've got.

    I'd say maybe .15 - .25mA would be a basic starting point, but even if you don't have that it's worth a try. This is really just a guess based on what you might expect to see from a 2N2613 at normal temp

    I'm going to breadboard this and hopefully have some more suggestions

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    1. Thanks! do you think the matched fz-1 transistors that smallbear sales would work in this circuit?
      I think I'm going to breadboard this myself and see what I can come up with.

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    2. The one from smallbear is an FZ-1A set, and yes it would be the closest thing to this circuit.

      The MKI sets that I've gotten from smallbear were very poorly selected. Hopefully he does a better job with the FZ-1A set..

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    3. Has anyone tried the new layout with the Charge pump and voltage adapter?

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  29. Im having an issue with the caps being to large to fit on the board using stock. What voltage caps are you guys using? Those of you who have built this.

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    Replies
    1. since this effect only takes 3V, -3V to be exact, you don't need high voltage caps, just larger then 3V.

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