Friday, 7 March 2014

Shin's Music Dumbloid Special

And the "Special" version with the Jazz/Rock switch.  If I'd just added a cap I would have tacked this layout on the bottom of the first post, but I've shifted things around quite a bit, gained a row but lost two columns, and with this not being verified I thought it should have it's own thread to keep different version discussions/troubleshooting separated.  I think I prefer this layout out of the two as it makes better use of the available space and will leave more room for wires at the sides if you're putting it in a 1590B.

Thanks to Amplified Nation for confirming position of the Jazz/Rock switch which only needs a single contact and so has been listed as a SPST, but use two lugs of a SPDT if you can get them more easily and cheaply.








If you can't find an opamp that clips pleasantly and so can't get round the fizz in your build, then consider making this small modification.  Adding a back to back pair of diodes of your choice between pins 1 and 2 means that you'll get diode rather than opamp clipping.  It does make it a bit closer to a Tubescreamer but the other changes will still make a difference and some people will think it's better to be closer to a Tubescreamer and sound good, than closer to the original and sound fizzy.  Or if you want both options just build the original and add the diodes on a switch between pins 1 and 2.





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71 comments:

  1. boy. not much of a' jazz mod' to just add a 470n cap before the 22u output cap, but you did a really nice job shrinking it down by two columns and only adding one row.

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  2. I liked that big bloom better. That thread at fsb is hilarious.

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  3. has anyone found a schematic or layout of love pedal high gain tweed twin?i really really want to findout whats in it.

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    1. There's a 9/10 chance the High Powered Tweed Twin is little more than a mode on the Les Lius. I wouldn't be surprised if that's what it is.

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  4. So with this, if we figure out a way to add a cab sim out...we have something close to an Ethos overdrive?!

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    1. Well a D pedal into a cab sim will at least get you some of the way there, but the Ethos is very much more complex beast and on a different level to this altogether. It's one of the few boutique pedals that I think deserves the price.

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    2. Agreed! I love my Ethos. I've never had the heart to open it up and see whats inside though. It's best to keep the magic sealed inside the enclosure. :)

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    3. I've seen the gutshots, you don't want to open it up, it's scary! :o)
      One thing is for sure, we'll never be doing a vero layout for it, I don't think I'd even want to build one on PCB.

      Shame there is a waiting list and we end up paying a massive premium to import to the UK (or for a UK dealer to take a ridiculous cut), or I'd buy one.

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  5. I built this one and it definitely works but I think that the transistors might be sensitive because mine doesn't sound like it should.. its got a tiny bit of fizz and the gain comes on super strong at about 10 o'clock. I bought several of the transistors from tayda so they probably have all of the same (wrong) gain range. any ideas of how to remedy this problem? Thanks.

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  6. I finished building and testing this one today and for me it won't ever make my board. The fizzy decay is ugly and the accent control just adds too it. I've tried opa2134 , jrc4558, lm4562, opa2604 , tlc2272 and the mc3317[ which was the best ] . I even tried a 2n7000 instead of the red led. The lower gain tones could be useful but as soon as the gain rises above about 40% it sounds way too fizzy for my taste. I'm not really sure if there is anything else to try to make it better

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    1. Thanks to you and Unknown for verifying. I'd really suggest trying a few different opamps because that's where you're getting the fizz from, not the transistors. Some will sound much better than others and so audition a few before writing it off. Thanks guys

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    2. Hey IVIark, when I'm getting a fizz like described above after building a pedal, is it always because of the IC? Or is that just the case for this particular pedal?

      Thanks for adding so much to the DIY community.

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    3. I've now also tried tl072 , lm833 and ne5532. Some of them I have multiples of and tried all of them . I have 1458's coming in the post I'll try them too.The 5532 were actually one of the better ones , but still it's annoying because it has a good base tone I could use but the fizz is too much so far.I also tried with a 150k and 470k impedance and not too much difference with my gear.

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    4. It is due to the IC. And i believe the original has a fizzy decay as well. There's no way around it with taking that much of gain from the opamp...
      +m

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    5. Yes it has to be expected when we know the opamp is going to be doing the clipping rather than diodes. It really is just a case of trying a few and selecting the one with the least fizz, John K mentioned that the MC33172 sounded best in his.

      One other alternative that may appeal to some people is to put 2 anti-parallel diodes between pins 1 and 2 so the clipping is coming from diodes instead of the opamp. It may be even closer to a Tubescreamer then but if it improves your pedal then why not do it? I may add a modded layout for it actually.

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    6. funny, that added pair of diodes was one of the first mods I did to mine, and it did help with curing most of the fizz, but once I installed the MC33172 chip, I no longer needed them so I removed them.

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    7. Where did you get your MC33172 from John? They seem expensive on eBay and so wondered if there was a good source elsewhere.

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    8. I got them from Mouser (back when I was building the Seamoon Funk machine) but it appears that they no longer stock them - bummer!

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    9. looks like they're available and super cheap on your side of the pond but you have to buy a minimum of 50!

      http://www.anglia-live.com/products/Semiconductors/Linear/223631001_8P-DUAL-LP-SINGLE-SUPPLY-AMP

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    10. Ooh excellent, thanks for the link. I'll get some from them I think, I just need to get the order up to £30 to avoid a handling charge so I'll have a root around and find something else to buy.

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  7. Nice, Nice, Very Nice. Built the Special with Diodes using an OPA2134, and a pair of BC549B's, also had to use two B50 for Accent and Tone. Can see what people are talking about with fizzle, but it seems only to occur at the max CW of Tone, disappears when backed of about 10%. Conversely, does squeal in the same range when the gain is max CW. It is not boxed, so loopy wires may be contributing to some degree. May try some other IC's, and may put the diodes on a DPDT

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    1. Finally got a good tone from this using a ne5532 and 1n914 diodes. I tried a mc33172, unfortunately it didn't work for me.It sounds great but as IVIark has said it does sound closer to a TS

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  8. Just finish but tone and accent never working. Only one thing I don't have the opa2134 and i tried LM833N and sound like that. With 4558 and tl02 never sound..

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    1. Sounds like you may have a poor connection at your IC socket. Use the diode tester mode on your multimeter to check the front springs and rear soldering are connecting properly. A couple of times on here a faulty build has been down to a break between connector and post in the socket.

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  9. I've checked three times all rear soldering and changed the socket, but nothing, also I've found a ops 2134 and with this one never sounding at all!! Only one thing that I have different of original TOC is the two BC548 instead of BC548B..

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  10. Replies
    1. It's no problem using those transistors, so that isn't your problem. But as usual with these things to be able to offer any advice you really need to post all transistor and IC pin voltages so we can see what area seems to be the problem.

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  11. OK.

    OPA 2134 BURR BROWN

    1. 0,08
    2. 0,26
    3. 0,15
    4. 0,00
    5. 9,14
    6. 0,08
    7. 0,09
    8. 0,08

    Q1 AND Q2 BC548

    1. 9,14
    2. 0,07
    3. 0,00


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    Replies

    1. I'm assuming you've got your numbering wrong, ICs are numbered like this:

      1----8
      2----7
      3----6
      4----5

      I'd expect the base and emitters of both transistors to be higher than that so something is definitely wrong there, as is the voltages at pins 1, 2, 3, 5, 6 & 7 of the IC. First things first, something must be wrong at the beginning of the circuit because of the voltages you're getting at Q1, so from the input check values, placement and soldering for:


      Input wire > 1M and 100p to ground

      Input wire > 470n > 100R > Q1 Base

      Q1 base > 150K > Vref

      Q1 collector is 9V which is expected so that is ok.

      Q1 emitter > 10K > ground

      Q1 emitter > 1u > IC pin 3


      There must be a problem somewhere with the list above, and if that is corrected the other voltages later in the circuit may also be corrected, so that could potentially fix everything. But you're going to have to go over it extremely carefully to check everything is correct as per the layout.

      Also check for unwanted bridges around your soldering, check that all cuts are clean and no copper is left which may be causing a short, and of course check all soldering for cold joints.

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  12. just for future reference, keep in mind the pinout of an IC. they are like this:

    http://johnkvintageguitars.homestead.com/Effects/misc/Chip_pin_number.png

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  13. Sorry I have inverted 5 with 8 pin and so the 2nd row. Ok meanwhile I try to find the error..
    Thank you very much!

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    1. These are the pics of my effect, I never found anything but still never work!

      http://www.diyitalia.eu/forum/download/file.php?id=9310&mode=view

      http://www.diyitalia.eu/forum/download/file.php?id=9311&mode=view

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    2. Have a look here: Fault finding a build. Go through the sections and if you're still having no luck post here again with the required info mentioned in number 6.

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    3. I have already check all and posted my voltages, the components and the traces it's all ok but I haven't the right voltages...

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    4. Where have you posted your voltages?

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    5. OPA 2134 BURR BROWN

      1. 0,08
      2. 0,26
      3. 0,15
      4. 0,00
      5. 0,08
      6. 0,09
      7. 0,08
      8. 9,14

      Q1 AND Q2 BC548

      1. 9,14
      2. 0,07
      3. 0,00

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    6. Well most of them look wrong, and it suggests to me you have a problem with your reference voltage. Check the voltage on the second row from bottom, it should be half your supply voltage and so around 4.5V. If it isn't 4.5V then you need to check values and soldering of the two 10K resistors connecting to that row from IC pin 4 (ground) and IC pin 8 (9V). I think you may find a short around there or maybe a bad solder joint.

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    7. I,ve found an error in a cutting hole. I've repaired and now have on Q1 and Q2 9,14, 7,3 7,2 and on the IC 1,2,3,5,6,7 - 7,3v 8 - 9,4 and 4 0,00v and no sounds at all

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    8. Voltages on the bases and emitters are too high now. If the voltages at the transistors are exactly the same, then are you sure the cuts are complete on the base and emitter rows? Re-do the cuts to make sure.

      Also reflow the solder on the link connecting all the ground rows together.

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    9. I four the error! 2nd row from bottom have a wrong link with the ground! The pedal now sound perfectly!
      Thank you so much!

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    10. Excellent, glad you got it sorted

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  14. Hi guys, first up: Thanks a lot for these layouts, Mark!
    I got one question regarding the second version with the added clipping diodes.
    Your last sentence says: "Or if you want both options just build the original and add the diodes on a switch between pins 1 and 2."
    Could you (or someone else) elaborate on exactly how to wire that switch and what type of switch would be needed? I got an SPDT switch, but thinking about it, i guess i'd need a DPDT switch to make this work, right? (I'm thinking: one leg of each diode into the board (row 5 for example), the other legs each to one of the outer lugs of the DPDT switch, then the middle lugs of the DPDT switch back into the board (row 7 then))

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    1. A DPDT switch would be neater because you can solder the diodes across the poles. Look at the recent layout for the Mesa Boogie Grid Slammer, add that switch (you could even include the Timmy clipping option to to make the most of the switch) and get your feed to the switch by connecting lugs 2 and 5 of the switch to pins 1 and 2 of the opamp. If you use a DPDT on/off/on you'll have Timmy clipping in one position, Tubescreamer clipping in the other, and original Dumbloid in the centre off position.

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  15. Hi, I might be a little thick here. but there only seems to be one wire connected to the accent pot. Is this correct?

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  16. Replies
    1. Many thanks. I was being thick.

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  17. I'm really new to pedal building and hope that someone can help. I am building the Dumbloid Special and tone 3 goes to accent 1. In the diagram there is only accent 2. Can someone please share pictures of their working build including all wiring to the switch with diodes as well as all wiring to the pots? Your help would be greatly appreciated.

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    1. If you look at the offboard wiring page http://tagboardeffects.blogspot.co.uk/2012/02/offboard-wiring.html there is a little picture which shows the numbering of the pot pins.
      For your question, you take a wire from pin 3 on the tone pot to pin 1 on the accent pot

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  18. Hi

    I'm currently making this pedal on a stripboard but I'd like to develop a board. does anybody have a schematic of this?

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    1. Thanks |v|ark, I've found it.

      I was giving consideration to make my own PCB as I cannot get this to work. This is my first stripboard project. I made 2 pedals from printed/developed PCB few years ago.
      After cutting the board I've tested all tracks for shorts and it was OK. I've checked each componenet before soldering with multimeter it seemed OK. I've retested the board for shorts after soldering and it also seemed OK.
      When I connect guitar the only thing I hear is buzz which gets louder when I crank the volume pot. I've been trying this for 2 days straight and still cannot get it to work.
      Can anyone give me a hand with this. The voltages on ne5532 are:
      1 - 4.59
      2 - 4.78
      3 - 4.78
      4 - 9.23 (same as batt)
      5 - 0
      6 - 7.82
      7 - 4.72
      8 - 4.75

      Q1
      B - 0
      C - 9.23
      E - 9.25

      Q2
      B - 4.73
      C - 0
      E - 4.61

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    2. Some very strange voltages there. How have you numbered the IC lugs? It should be like this:

      1---8
      2---7
      3---6
      4---5

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    3. Correction
      I messed it up copying it from the paper:
      5 - 4.75
      6 - 4.72
      7 - 7.82
      8 - 0

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    4. Well you have 9V on pin 4 where it should be 0V, and 0V on pin 8 where you should have 9V. So to me it looks like you've reversed the supply leads.

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  19. Thanks |v|ark for fast reply. I appreciate it.
    Well, i had to take a rest before I checked it again. I was giving the votages measuring from the positive pole of battery and did not invert them before writing it here. Turns out that I've soldered Q1 1 track down. Reseoldered it and I got the output working. The only thing now is that it seems that only pot that has any influence on sound is gain pot. All the others don't do anything. I'll give it another check this night or tomorrow.

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  20. Hi guys
    Just to thank you for the layout and the assistance. I've managed to find time and debug/complete the pedal. Sounds great. Images are here: http://goo.gl/RzrOvz will try to make video also.
    I've completed this mostly from the parts laying at home and what i could purchase locally. I was not satisfied with quality some parts, mostly connectors, so I have ordered kit from BitsBox and I'm planning to make a second one with printed PCB.

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  21. Having problems. Signal passing through but sounds like a rubbish fuzz. Voltages I have are

    IC
    1=4.25
    2=0.12
    3=0.5
    4=0
    5=9.23
    6=4.97
    7=0.4
    8=3

    Q1=
    C=9.23
    B=0.5
    E=4.18

    Q2=
    C=9.22
    B=6.12
    E=8.45

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    Replies
    1. Your voltages don't look right so start at the IC. First I think you got the numbers wrong, a DIP8 IC is numbered like this:

      1---8
      2---7
      3---6
      4---5

      Pins 2, 3 and 6 (6 shown as 7 in your post) are too low so check all connections around there and see if anything is amiss. Check soldering and cuts between pins.

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    2. Did a bit of cutting and re-flowing. I now have (in the correct order)

      1=4.2 8=0
      2=4.6 7=2.7
      3=0.4 6=4.23
      4=9.23 5=2.5

      still sounds very fizzy and im getting squeling when gain is at about 50%.

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    3. You are showing 9V on the ground pin (4) and 0V on the supply pin (8). Those are very much the wrong way round. Have you mixed up the wiring from the supply adapter?

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  22. Hello, everyone! I'm a complete beginner when it comes to electronics. Nevertheless, I jumped right into making this pedal. As I don't have a clue to what I'm doing, it didn't turn out the way I hoped it would. The volume is quite low when I turn the pedal on. The gain seems to be on full constantly. The gain pot acts as a volume pot. The tone pot and the volume pot both act as tone pots. I compared my work with the illustrations over and over, but I can't see what's wrong. Do any of you experts have any ideas to what I've done wrong, apart form attempting to build this thing in the first place?

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    Replies
    1. A description could never tell us enough to offer any real advice. Measure the DC voltage between all IC and transistor pins and ground, and that will give us a good idea where your problem areas are.

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  23. Well, I checked the reading as suggested and this is what I came up with:

    opamp:
    1-4,44 8-8,9
    2-4,44 7-4,45
    3-4,43 6-4,44
    4-0 5-4,44

    Left transistor:
    C-8,9
    B-4,2
    E-3,66

    Right transistor:
    C-8,9
    B-4,27
    E-3,73

    Does this mean anything to you?

    Cheers!

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  24. Would a TLC2262CP work? I used one in my Zen Drive and its awesome.

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  25. This is my second build and with no clipping diodes fitted the sound seems boosted but very clean. I did notice one variation between the supplied kit and the schematic. The kit has a 1k8 resistor, and the schematic shows a 1k5. Would this make a noticeable difference please ?

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  29. just finish the pedal today, happy build,
    and elegant sound, want to add a booster,
    any idea of the boost that used on model B?
    share some shots here :
    https://goo.gl/photos/Ve8CSBNJeLMpS6oRA

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