Thursday, 24 May 2012

Skreddy P19

Just to give mirosol a bigger headache deciding which Skreddy pedal to build next .... :o)

Info from Marc about the excellent original:

Specifically tuned to the sound of a block-buster 1979 album and emulates the "magic" 70's era fuzz pedal that was somehow clear and articulate on high notes while still fuzzy and aggressive on low notes, without excessive low-end muffiness or high-end fizz.  The mids are scooped just enough to keep it from sounding congested, the lows are rolled off just enough to keep it from sounding wooly or boomy, and the highs are gentle, present, and well balanced.

Its clarity will encourage you to dig in and express yourself; it's not an overwhelming "wall of fuzz" type effect.

A wide variety of aggressive and clear-sounding applications, particularly excelling in sustaining, biting, legato lead work








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64 comments:

  1. Awww... Thank you. I'll try to find time tomorrow and build this :)
    +m

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  2. So cool fuzz, need to built it soon!
    Please do the Catalinbread SFT!!!

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    1. http://s647.photobucket.com/albums/uu198/tonmann/Catalinbread%20SFT/?action=view&current=CatalinabreadSFT-Schematic.jpg&sort=ascending

      Any good?

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    2. I bought this kit thinking I could build it, but no I cant .Can any one do this for me ,I would pay. Thanks stu.

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    3. Hey Stu,
      What is the reason you can't build it? Were abouts are you? If you are in the UK i would be happy to help.

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    4. Hi Gavin ,I live in Dorset ,WIMBORNE MINSTER. Its all new to me, I ve been reading up on it, my hands shake to much.

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  3. Replies
    1. That was quick! Nice one

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    2. Good thing that someone beat me to it.

      Now i can concentrate on two boards i have on the way..
      +m

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  4. Finished this one today. Sounds good. I ordered BC550 transistors since I couldn't find the BC550C. Pinout was opposite so I just flipped them and they worked fine ( base was still in the middle ). I'm just wondering, does anyone know approx where the hfe should be for this to be close to the original? I measured the BC550s that I used and they were all around the 300 range. I just wonder if the BC550Cs are a little higher gain ( mine just sounds a tad more tame than the demos that I have listened to ). Regardless, still a keeper...

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    1. Last character after the model means the gain group inside the BC550. BC550C means that the beta/hFE is typically 520-580, but can be anything from 420 to 900. Here's the datasheet, check page 3:
      http://www.datasheetcatalog.org/datasheet/MicroElectronics/mXuwzwr.pdf

      As it's BC550C indicated in the schematic, i think you'd be better off with 2N5089 - rated from 350 to 1200. I guess it'll be easier to find hFE 550 from those than from random batch of BC550 without that C.

      Any NPN bipolar junction transistor should do. Can't say for original without measuring, but as 550Cs are what they are, the sweet spot could be between 520-580 hFE.

      Personally i would go lower, as the lower hFE usually tend to give out more warmth and cream.. :)

      Try all different transistors you can! I find it fun to test different hFE values on a single design :)
      +m

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    2. Possibly a stupid question, how can you easily measure hFE ratings?

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    3. Cheap multimeters often have transistor sockets to measure gain, like this one:

      http://www.ebay.co.uk/itm/261033541757

      I've also got a Peak DCA55 which can also accurately measure germanium transistors and tell you the leakage which is highly recommended.

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    4. If you have voltmeter without a transistor tester you can build a very simple gain and leak tester with spare parts. Details are in this article by RG Keen: http://www.geofex.com/Article_Folders/ffselect.htm

      It describes the process for germanium transistors, but it's exactly the same for silicon, except silicon doesn't leak so you can skip that part.

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  5. Thanks mirosol

    Bookmarked that datasheetcatalog link - I need to spend a little more time there.

    Just want to try a little more gain. It does sound good as is but I would like to see what it sounds like a little more goosed. I will order the 5089s and a few others to test and see the differences.

    This was my 14th build. After each one that I complete, I tell myself to take a little break and play the ones I have - then something else gets posted that I have to try. Silicon Fuzzmaster is next.

    Addiction...down the road to ruin

    Thanks again. And IvIark for all the layouts and information!

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    Replies
    1. :)

      Believe me i know. Finished the Klon yesterday and that was my 46th build to date. Success leads to addiction. This is probably the best hobby i've ever had..
      +m

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  6. Just got in my BC550Cs from Mouser. Measured a few to around 600-ish hfe and loaded them up. This thing sounds GREAT now! Time to build a second one...

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  7. Thanks for the layout. I've got a question about the wiring for "Tone 3" though. The layout shows Tone 3 going to the board as well as the Mids switch. Do I run 2 wires from Tone 3, one going to the board and the other to the switch or is there something else that I'm missing? Thanks a lot.

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    Replies
    1. Take the wire from the board to the switch, and then daisy chain out of the switch to the Tone pot lug 3.

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    2. Thanks for the fast response. It is very much appreciated. As well as all your great layouts. Peace!

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  8. Just build this one and it's somehow very low on gain. Also the sustain pot on 0 decreases volume a lot which is very different to the demo's I've checked on youtube.
    I've build the exact spec with 4x BC550C. Will remove them tomorrow, place sockets for the transistors and diodes and try some different ones.
    Do you have any other tips what might be an issue? Might be related to the sustain I would guess?

    Thanks!

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  9. If I check the datasheet of the BC550C here: http://www.datasheetcatalog.org/datasheet2/f/0c8rp5lqo211di4l708pozs0skky.pdf it seems that the placement of them in the vero is incorrect? But if that's the case then it shouldn't be working at all should it?

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    Replies
    1. The EBC and CBE placement is correct, the orientation of the BC550C is not. I didn't check the datasheet before I placed them so that's why it's probably very low gain. Can it be that in the current state of my vero that the transistors aren't working and that all the drive I'm hearing comes from the diodes? With fuzz faces they don't work when the placement is incorrect. Wonder if that's possible. :D

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    2. Yes I've got a standard template somewhere that I use for muffs and it was probably setup originally for 2N5088's or similar. The top right 820R resistor sets the minimum gain for the Sustain pot so if you want to increase it just up that resistor value. I suspect it will be ok once you've turned the trannies 180 degrees.

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    3. The transistors must be doing something or you wouldn't get any sound through at all, they're probably just acting like extremely badly biased amplifiers.

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    4. I rotated the trannies 180 degrees and it's fully working now bro! Will check the datasheet first next time. :D It's always a been to use braid to desolder and leave the vero intact.
      Nice variation on the fuzz/muff theme. ;-) Thanks for the vero!

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    5. Still remains funny that the circuit works when the trannies are reversed. ;-)

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  10. Hi, what capacitor can I add to the DPDT to have a slightly scooped mids option?
    Cheers,

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    Replies
    1. You couldn't add anything to the DPDT to do this. That adds a capacitor to the circuit which is already flat, and any additional capacitance will boost the mids not cut them.

      To do what you want you would first need to swap the 6n8 on the board to something which will give you the scoop you want. It may be worth socketing the position so you can experiment but I'd suggest 2n2 may be a good alternative value here to give some scoop, or 4n7 would give you a very slight scoop. Then swap the cap on the switch to give you the boost that you want (smaller value like 2n2 or 4n7 to keep it flat, 6n8 or 10n to give you a boost (depending on what cap you ended up using on the board.

      If you socket the board cap you can experiment to get the boosted level you want without having to mess with the switch cap. The cap in the switch is added to the value of the cap in the board, so if you like the 2n2 board cap for the scooped position, and a 10n board cap gives you the boosted level you want, then keep the 2n2 in the board and put as close to 10n - 2n2 in the switch, so 7n8 ideally, 8n2 probably as the closest standard value.

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    2. Thanks a million.Now in the original schematic, is the switch a spdt on-on?

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    3. Probably. Marc puts the additional cap on the board, whereas I put it directly on the switch. I like it my way because you have the option of using a 3 position switch and adding an additional cap to the other throw to give you 3 switchable base frequencies to start from. You can also take out the switch and replace the cap to change the mid level without having to mess with the board at all.

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  11. I just finished this, it's working really well... except I get a massive volume drop when engaging the 6n8 mid boost cap. Is this normal?

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    Replies
    1. No.. Bad cap/switch or bad joint. You seem to be getting your signal to ground when that switch is turned.
      m+

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    2. I'm almost certain it's a bad switch.
      For what it's worth: I found a really good combination of transistors:
      Q1+4 are MPSA18, and Q2+3 are BC550B. That makes a really aggressive, cutting Muff that just sounds excellent.

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  12. Hi guys, this is my latest adventure. Getting better works first time out...for the most part :). The only problem I am having is when I engage the mid boost 6n8 cap on the switch I get a squeal with anything more than barely nudging the sustain. I tried a number of different caps and it seems to begin to diminish at @ 0.01u. I have not swapped out the switch yet, but could it be the switch? Seems odd to me.

    Thanks!!!

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    Replies
    1. What a dumbass! First the good news. I learned all about oscillation! Went crazy chasing it. The re-read the above just in case and while doing so I realized I had wired Sustain 3 to the boost switch NOT Tone 3! Oscillations all gone now. This thing rawks! I did end up with BC550's and 2 clocked in around 350 hfe (used those for Q1 and Q4) and the other two were 385/90-ish. I might toss in a 5089 as suggested above and see. The on to boxing this thing up! Great site again...thanks for all the layouts!

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  13. Hello,
    I'm new to electronics but can solder.
    Got one of the P19 kits and followed "Greeny's Vero Build Guide".
    1) Have built the circuit board (looks successful)
    2) Drilled Case and fitted pot's and switches.

    3) Here's where I got stuck.

    I am not finding it easy to interprate how to connect the board to everything else.
    I'm confused by the diagram without having pictures of the pots and switches.

    a) I see "Volume 1", "Tone 1", "9v", "Input" etc in the board diagram. I guess that means connect to the +ve terminal?
    Where do I connect the -ve to? Ground?

    b) Each Pot has 3 terminals. Which ones do we use?

    c) How do we connect the 9v battery in conjunction with the 9v transformer input?

    d) Wiring up the Main switch. Saw: http://www.little-black-box.co.uk/images/uploads/wiring-diagrams/3pdt-wiring.jpg
    Is that correct?

    Thanks in advance for any help.
    Warren

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    Replies
    1. Look at the pot photo on the Offboard wiring page in the menu and everything will become clearer. You'll find a wiring diagram for the switch there too

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    2. Thank you. Looks like what I need.

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    3. hello what 1979 album is this based on?.. i watched the video and know its a hybrid big muff just curious what the blockbuster album is?Hey IVI ARK just want to give you a huge thank you i been building for two months and just finished pedal number 10. thank you so much.. i am actually getting the hang of it. still not quite ready to do a layout yet but thats the goal.

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    4. The '79 album is Pink Floyd's The Wall

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    5. Hi Ivlark,
      Are you around? Wondered if you could help please?
      Warren

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  14. Hi Mark,
    I wired it up but it is not working.
    I used the http://www.little-black-box.co.uk/images/uploads/wiring-diagrams/3pdt-wiring.jpg method of wiring the PDT.
    Bypass works but when on the level is almost nothing.
    Would it help if I sent you some photo's?
    Warren

    ReplyDelete
    Replies
    1. If the bypass is working then you can forget about the switch for the moment, that won't be the issue. First things first with something like this we need pin voltages for all the transistors. Measure the voltage between each pin and ground and post the results here. That is usually the best guide as to where your problem is.

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  15. Is the small 100n in the corner by Vol 1 and 3, the same as the other four larger 100n?

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    Replies
    1. yep. it looks different because it looks like a ceramic because it spans only 2 rows, so you can use a multilayer ceramic cap instead of a typical poly cap. you could use a poly cap but will need to bend the legs to make it fit nicely.

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    2. Awesome, thanks. 1st build, coming along swimmingly except for enclosure toner transfer. Have tried all the possible recommendations.

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  16. This is my first build. I've got the board done, the box etched and drilled, and I'm doing the hookups. Shouldn't there be an output wire from the board?

    Maybe that's a stupid question, but offboard wiring has been a challenge for me, esp since I bought a bunch of DPDT instead of 3PDT. I come from the 80's and didn't know what has happened since! If it's just me, an amp, one or two effects, no live playing . . .regular DPDT wiring with an LED doesn't suck that bad does it?

    ReplyDelete
    Replies
    1. at the notes it says that your output comes from volume2.
      now if you want an LED and you only have dpdt footswitch, then you have to make an extra board for the LED like this one

      http://tagboardeffects.blogspot.gr/2014/01/millennium-bypass-2.html

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    2. Oh I missed that. But the illustration only has Vol 1 and Vol 3?

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  17. Oh wait . . . you mean it's the Volume 2 solder lug --> out?

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    Replies
    1. yeap! that's right!
      at the top of this blog, there are some really useful guides that you could/must read before starting building any effect. at the forum also, there is a library that covers a lot of beginners questions.

      my advice?
      read as much as you can from those guides along with the questions and answers at each post.
      that could save you tones of time.

      good luck and welcome aboard!

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  18. Thank you. Actually I did read all of those and tons more offsite, but was still confused. I get it now though!

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  19. To anyone building this. My first try used (4) 550C at over 600 hfe. Based on an earlier comment, I found (4) 550B that were al around 400 hfe and much closer matched. The difference was night and day. With the 550C it was unpredictable, sounded more like a distortion, and the tone was not effective. With the 550B's it is creamy, tubelike, the tone and mid-switch are highly effective and the whole thing is just "right".

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  20. Follow up: I've noticed that when using an adapter I get noise in the background similar to 60 cycle hum, but not exactly. Batteries are dead quiet. Do others have this issue? I can try other adapters, but wonder how prevalent this is?

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  21. Just built this and it seems really quiet, to get the level i have when bypassed the volume pot is all the way up, tried changing the pot, tried rotating the transistors and tried a set of 5089's to see if that was it, can't figure it out, the sound is there, just not very much of it

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  22. I forgot to put the cap 330N , I fed the pedal and not working . Then I found the problem , so I added the missing chapter and I turned on the pedal but at the third attempt he struck the led and the pedal still does not work . Can someone help me
    thank you

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  23. I've replaced tranzistors and now the pedal worked. Then when i connected the middle boost it daesn't work...
    Why?

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  24. I completed this circuit and continued to congratulate myself on the tidiest circuit I've done so far, only to find it doesn't work and I have tried all the usual things and I'm sure it's the circuit as bypass etc. is fine. I've done the pin voltages as best I could for the transistors, just wondering if anyone can help. I'm 99% sure all the components are in correctly, and all accounted for and soldering neat and strong.

    Q1 E: .093 B: .667 C: 1.91
    Q2 E: .051 B: .614 C: 1.92
    Q3 E: .083 B: .659 C: 1.95
    Q4 E: .065 B: 1.38 C: 1.92

    Ta.

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    Replies
    1. Put a post in the debugging section with some hi res photos and we can all have a look. Another pair of eyes always helps.

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    2. Er.. sorry but where do I find the debugging section?

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    3. Click on the Forum button on the bar above and its in there.

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