Tuesday, 29 January 2013

MXR Distortion+ w/ Wampler mods

Another request. Wampler's mods for MXR Distrotion +, as seen at Premier Guitar magazine's website.


56 comments:

  1. I hate to be the bearer of bad news but it doesn't look like the 220nf cap is connected to anything on the third row at the moment, is the cut between the 220nf and the 1k resistor meant to be there? Looking at the schem it doesn't seem so.

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    1. Well spotted. That cut was leftover from me compacting the layout. Fixed.
      +m

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    2. No worries, I was on a conference call with work that wasn't very interesting otherwise I probably wouldn't have spotted it ;) Miro's layouts: Saving people from work place boredom since 2012!

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  2. Replies
    1. You built it? I'll fix the labels.
      +m

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    2. Hi,
      I am just ordering parts for this,what would be the best equivalent for the 1N34A diodes please - having trouble getting some.
      Thanks

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    3. Just search for them on eBay, otherwise just use a 1n4148,the sound won't be quite the same though.

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  3. Verified! Sounds great, it keeps the tone of the Dist+ but has a great versatility that makes it more friendly with your rig. Thanks!

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    1. Thanks Luis! You've been building a lot lately!
      +m

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  4. I don't have an LM741 on hand, but I've got a stash of other ICs I'd like to use if it doesn't deviate too much from the way this pedal is supposed to sound.

    I'm still a bit ignorant of the differences between these chips, so bear that in mind.

    I've got a.. hmm.. a LM308 and an odd UA741cn. Do either of those sound like a decent substitute? It's not a big deal to get a few LM741s, I just hate to stop in the middle of a project to wait a week on the mail, especially if I've got a find alternative.

    Thanks!

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    1. UA741cn and LM741 are the same, just different manufacturers I think. There shouldn't be any problem substituting one for the other. Someone else may have a bit more info on this though.

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  5. So am I correct in thinking there are 3 switches on this on ??

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  6. I'm about to build this as my first "REAL" project in a couple of days, just waiting on my parts to come in. Is there anything I sound keep in mind??

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    1. It isn't a race so just take your time. Double check everything that you do, component values, track cuts, link placing, component placing, wire connections. Count rows and columns to make sure you're getting everything where it should be.

      Don't solder up the stomp switch until you know the board is working properly so you're not adding another potential point of failure. Just connect the input and output (volume 2) wires from the board directly to the input and output sockets (use a small terminal block to make the connections) to test.

      Follow all that and I'm sure you'll be fine.

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    2. Thanks, now I can't wait to get started!!!

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  7. I started a blog that follows me making this pedal. It's got a lot of high resolution pictures of each step along the way. Check it out at http://pedalprojects.blogspot.ca

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    1. Excellent, thanks for the link Dimitri

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    2. I did it, I build this thing and it sounds great!!!
      One thing I have a question about it how do I know which side of the switches turns on and off the the components. I used on/on SPDT (3 lugs) switches and soldered just two of the lugs. So how do I know which side let's signal pass???

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    3. Also it get's kinda bassy when I turn the gain up, is that normal?

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    4. I don't understand the question. You're using a SPDT but you're using is as a SPST (with only 2 lugs being used), so the effect is either on or off.

      If you imagine looking at the back of the switch like this:

      1
      2
      3

      The when the switch is in the down position, the contact is made between lugs 1 and 2. When in the up position the contact is made between 2 and 3. To get this clear in your own head get another switch and hook it up to your multimeter in the audible diode test mode. Then you will hear when the contacts are made when flipping the switch.

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    5. Incidentally, I've just looked at the pictures on your blog and you've done a great job of it, and even more so considering it's your first build

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    6. Thank you, that means a lot! I'm a big fan of this site, with all the guides and quick responses to questions, it gave me all the help I needed. It's a really nice set up you have here. For my next build i'm thinking of the Lovepedal Kalamazoo
      BTW, the post above answered my question

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    7. I've added a link to your site in the links at the side, I think it would be a great read for someone needing some inspiration, and it does emphasise that taking your time is the way to go which is great advice. Good luck with the Kalamazoo!

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  8. I've built this using a LM308N and it sounds huge, kind of a cross between the RAT and DIST+. The tone pot however doesn't seem to have much of a range/effect. I noticed on the premier guitar site it mentions using a 100k pot for the tone but this layout and the schematic on their site shows a 1M, maybe an error?

    The smooth drive switch turns the sound very fuzzy (almost velcro fuzz factory style) which is cool! The bass boost sounds spot on. The compression switch is also quite subtle but works well - I was thinking of putting an SPDT on off on in there with a cap for 'high' and 'low' compression options, how would I go about that?

    Thanks, learning a lot!



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    1. The article has both:
      "A much better use would be to wire a 100k pot in series with a .0022uF cap in place of C5. This will act as a tone control."
      and
      "Change C5 to a .0022uf and wired in series with a 1m audio taper pot to act as a tone control."

      Compression switch adds 10n cap in parallel with 1n, so you should figure out how to add one more cap in to that mix.. Or you could just play around with values for those two..
      +m

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  9. I just finished this, but the smooth switch leaves something to be desired...it is super quiet. I used IN4007's instead of IN4001's for D5-D8. Also for the 330nf and 1uf caps I used some monolithic ceramics. The distortion is a little bit grainy at lower drive settings, all the way up sounds decent though. Any of that an issue?

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    1. The smooth switch introduces the other clipping diodes which tends to cut the volume a little but it shouldn't be too drastic, it might be worth check the orientation of diodes 1, 2, 5 and 6. There shouldn't be any problems with the diodes and caps you've substituted, 1n4007s are very similar to 4001s and Monolithic/Multilayer ceramics shouldn't sound much different from any other decent cap.

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    2. I just did this as well and my smooth switch is a little weird. It didn't work at all at first but I swapped out one of the 1N34A's (which I routinely snap in half) out for another one. It sounds like the almost clean signal with some low level distortion behind it (at a lower volume) Like 2 separate signals. Anyway, can I use some other diode there? BAT41's or something? I assume diodes are almost always interchangeable.

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    3. Yup. You could try on any diodes. 12V zeners sound really good too. I think that schotkys are a bit softer than 1N4148s. I've had too many dodgy 1N34As to call them good diodes for anything. You'll need two pairs of pliers to bend them :)
      +m

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  10. Built the circuit on vero and tested with my breadboard but I'm getting a ton of squealing once the drive and volume go up about half way. I will probably use shielded wire on the input and I'm hoping an enclosure will cut down the squeal. The "Smooth" switch sounds killer and does not squeal. The "compression" switch is very subtle but I find that it really shines when used in conjunction with the "Bass Boost" switch. Any ideas to reduce the noise????

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  11. built this one today. it sounds great! (mine's not noisey or squealing at all).
    I slightly rearranged some of the components on miro's layout so the very fragile 1N34A's would lay down easier and made more room for the 22uf cap.. since I use mine for bass, I also changed the 1n input cap to a 2n2, and the 10n compression cap to a 22n. I love this one. IMO, it's WAY better than a stock Distortion+.


    here's a pic of my board while testing it:

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/DOD-MXR/Dist_Wamplermods-03.jpg

    here's my modded miro layout:

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/DOD-MXR/WamplerDist_Verified.png

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    1. Very cool. Thank you John!

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    2. The high and low pass input caps on your board are actualy the opposite with the ones showed on your layout. Which to follow, your layout or your finished and aproved board?

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  12. DONE!!!........and it sounds great.

    pics:

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/DOD-MXR/WMD-01.jpg

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/DOD-MXR/WMD-02.jpg

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    1. Real neat work! Thanks for sharing!
      +m

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    2. This comment has been removed by the author.

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  13. This comment has been removed by the author.

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    1. I could use some help from someone with more electronics knowledge than me.

      No luck so far with the slow power up, although the noise is much less once I put it in the enclosure.

      Pin 3 of the the 741 slowly climbs from about 1 volt to 3.8 or so after I apply power. The effect turns on when pin 3 gets above 3 volts. I don't understand what can be causing the slow ramp-up of the voltage on pin 3.

      I pulled the IC from the socket and lifted the 10k resistor that connects to pin 3 hoping to isolate just the voltage divider that should be providing 4.5v to pin 3, but have the same slow voltage climb at the pin 3 socket.

      I then replaced 2 of the 1 Meg resistors and the 22uf Cap, no change to the slow power up.

      The circuit is simple enough to scrap and rebuild, but I can't let it go!

      Is there anything else I can try?

      By the way, after it powers up. the effect seems to work fine for a little while, all controls and switches appear to be working although I don't hear much of a change with the compression switch. After a minute or so, the the volume and distortion starts to drop out and come back as if pin 3 is dropping below the required voltage. I haven't tried to monitor the pin voltage while playing.


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    2. I built another from scratch, sounds pretty good.

      2 issues:
      This one also powers up very slowly. I apply 9V DC power and after a few moments the pedal finally comes alive. Is this normal?

      Also, there is a pretty big volume drop with the smooth switch engaged. Is this normal? I used 1N4001 and 1N34s in series as in the layout.

      Thanks,
      Mike

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    3. This build was squealing all over the place when it was on the breadboard. Once I boxed it up, all of the squealing went away and it's nice & clean sounding now.

      I built two, one Tagboardeffects version and one with the Kallas mods. They sound incredible.

      I used 1N270’s on the Tagboardeffects version just like the original MXR specs and I tend to prefer the fuzzier sounds of the 1N270’s over the 1N34A’s. Just like others have noticed, there is a slight volume drop when using the Smooth switch and also a short delay when powering up before any sound is available... it's like a mini-tube amp :)

      I plan to remove the 1N34A’s from the Kallas mod version, put in some sockets, and try it with some 1N270’s. For both pedals I used LM741CN IC, 1N4001’s, 1uF tantalum capacitor, and all three of the SPST switch mods.

      The MXR Distortion+ was my very first pedal back in 1979 so I really dig hearing this sound again. A true classic! This was a dual purpose pedal back in the day because I connected it to the auxiliary tape input of a Teac reel-to-reel for some out-of-this-world space feedback effects.

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  14. I was taking a look at the schem in premier guitar's page and it shows the C5 like a 0,0022uF. Shouldn't it be a 2,2nF and not a 22nF like in the vero layout here? Although, thanks for the great layout.

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  15. Hey,

    During my build, I guess I had some bad Ger Diodes, the diodes cracked apart. Can I use a 1n4148 as a sub for q1 - 4?

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  16. On the off board wiring, the Drive 1 connection is also the Smooth sw1 and Bass sw2 can these switch connections be made on the #1 lug on the drive pot?

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    1. As long as they're connected somewhere it'll work as described, so if that works best, yep.

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  17. Thanks Charles
    I'll complete the off board wiring and post the results
    Pat

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  18. Done and it sounds good! The bass smooth comp switches have significant appropriate effect. The smooth does give a volume drop but that's fine as long as you don't adjust on the fly. I used a tl071 and 1n34 diodes and I like the sound. I'll built one with lm741 and1n270s to compare

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  19. Update, My 1st build of this fires up and sounds good/great! but them if left on for several minutes its starts to get splatty and then dies. At first it was just in the non-smooth mode but now it just starts to go after a few minutes. I checked the battery voltage and that's good, I replaced the TL071 I used with a new LM741 and still the same symptoms. Any ideas what's going on? I don't see a polarity protection diode, is it possible I killed it by plugging it in, in reverse by mistake?

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  20. Update# 2 the 220n cap next to pin 1 was leaning on the IC, not contacting but leaking through the body? iDK but I bent it back and the problem dissapeared!
    Build #2 with LM741 and 1n270 diodes is the shizzz! Super dynamic and lively w/ harmonics

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  21. Hello. How to connect Volume 2 to the 3PDT wiring? Should i connect it with output Tip or with pin or 3pdt switch, which connects with boards output? Thanks

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    1. take a look at the offboard tab on top to see how to do the offboard wiring.

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    2. https://www.gearslutz.com/board/attachments/geekslutz-forum/379250d1389193345-ibanez-phase-tone-pedal-true-bypass-question-pic-2.jpg (dont read red quotes)

      output from mxr goes to the 3pdt or to the jack?

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