Tuesday, 24 January 2012

EHX IC Big Muff

I wanted to try this one out with a quad opamp and so thought I'd put together a couple of layouts, one for the 1977 version and one for the 1978 version with a tone bypass switch.

I have done a version of the 77 with all the diodes laid out on the board, but to keep the width down to allow this to be mounted in a 1590B box I decided to simplify the diode layout, so D1 and D4 are each 3 x 1N4148 diodes in series.  They're small enough to allow you to make these groups of 3 up yourself (and maybe cover them with shrink tubing) without looking unweildy on the board, so I thought it made the most sense to keep the layout as compact as possible.

Both layouts were put together with the TL074 opamp in mind, but if you use a non-fet based quad opamp then the 1M resistor from pin 10 to the supply rail should be changed to 820K.

Layouts were based on analogguru's schematics but are currently unverified, so if you build this up then please let us know how you get on.

IC 77



IC78

With 2 position SPDT toggle switch for Tone Bypass

82 comments:

  1. hi IvIark,

    do you know the version 3 and have you ever made a layout of this version or know any layout of this one?

    it's this: http://www.kitrae.net/music/big_muff_historyB.html#Version3

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    1. Hi Ivlark,
      Firstly, thanks for putting these layouts up, lotta fun to be had :).

      I've tried to build the 78 though and am having some problems. The overall sound is not being distorted and just comes through clean with some background static. I've probed the circuit and only get an audible signal at pin 8 on the IC. The gain, tone and tone bypass seem to be working. The gain behaves more like a volume, the tone definitely lets the treble though when open and is disengaged by the bypass.

      I've taken voltages from the battery and IC pins:
      v 8.22 batt, pins 1-14: 3.95, 3.95, 3.56, 7.9, 3.74, 3.95, 3.95, 3.97, 3.95, 2.64, 0, 0.92, 0.95, 1.39.

      I've checked and double checked my soldering and don't think I've made an error (not unlikely though). I had a look at the original schem but unfortunately can't yet follow it with the conversion from dual op amps to one quad amp.

      Any hints would be much appreciated.

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    2. Let me go over it again Cliff and I'll get back to you and let you know if I spot any errors this end.

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    3. I've been over the layout again and can't see any obvious mistakes. Take a high res front and back pic and post the links on here. I'll check it over to see if I can see anything.

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    4. Many thanks for checking. I've tried some different quad op amps but no luck. Here's some pic's http://www.mediafire.com/conv/f850556904dd16c0aac596d6e96340e8dccd39b605035e3c3b267001a58970e06g.jpg

      http://www.mediafire.com/conv/c40368d0e3dec612471a889494d5a3c3eb972e827ac534f4db3278a38cfc7fa86g.jpg

      http://www.mediafire.com/conv/9d54b8d027aff0822866d06cad8a248de83597ff3449905cb75108865cc258a66g.jpg

      Cheers,
      Cliff.

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    5. Well your voltages don't look too bad actually, maybe a little low but then you battery is a bit down anyway so that could explain it. All your cuts seem right and the components that I can see seem to be in the right place and value.

      One thing that is strange is that you're getting 8.22V at the battery but only 7.9V at the IC which suggests there could be a bad solder joint in that link. With your multimeter in diode mode, check consecutive rows (and in between all the cuts on the rows) just to check that you don't have a stray burr or wire bridging something it shouldn't. And bearing in mind the voltage it may be worth just going over the solder and reflowing to make sure all the joints are good. Are you sure that all the caps and pots are good? Measure the pots and caps in circuit may not give you a completely accurate reading, but it may give a few hints if something is way off.

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    6. By some strange coincidence I've just been involved in a conversation where the TL074 was being discussed and it was mentioned that the minimum supply voltage for it is 7V. It was also mentioned that you should always use a brand new battery with it.

      I don't know how accurate that is and I know you're over the 7V anyway, but as it's not too much above it, do you have a 9V adapter or another battery to test it with? Just to eliminate one other possibility.

      Delete
  2. Hi IvIark, I guess the 47r brings it down to 7.9v from 8.22v. I'll check it with a 9v power supply tomorrow and let you know how I get on. Thanks again, Cliff.

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    1. Incidentally how have you put the diodes together? They're responsible for most of the distortion so if the sound is coming out clean it might suggest an issue there. They need to be connected like this:

      http://i76.photobucket.com/albums/j6/IvIark_2006/DIY/EHXOpampBMDiodes1.png

      and so wrapped they'd need to go something like this (making sure the final legs don't touch the joints between diodes).

      http://i76.photobucket.com/albums/j6/IvIark_2006/DIY/EHXOpampBMDiodes2.png

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  3. Hi IvIark, i've tried with a 9.6 voltage supply, giving 9.3v at the IC but no change. I've also checked the adjacent vero strips for connectivity but didn't find anything. With the diodes I'm pretty sure that I connected them as shown in this schem (http://gaussmarkov.net/layouts/opbmp/opbmp-schem.png) so d1 to d3 connected in serial with d1+ and d3- connected to the board and d4 to d6 connected in serial with d4+ and d6-. I better double check though as I wrapped them up in the shrink stuff.

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  4. Tried to finish 77 today. Works almost right. I get wild oscillation while the sound is otherwise like it should be. Checked everything, but i might do it all over again tomorrow, just to be sure..

    Anyway, sounds good. Just if there were'nt that ear piercing oscillation..
    +m

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    1. Try swapping the 8K2 resistor for a 33K. I was reading about someone having an oscillation problem with it and that sorted things out for him.

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    2. Didn't make a difference. I'll probe it tonight or tomorrow to find out where the continuous squeeling stars...
      +m

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  5. Hmm. On that 77 layout, are you sure that 560K from 3rd strip to 9th is really 560K?

    After extensive probing i found that this resistor is causing the squeels. Swapped it for 100K and it sounded really bassy, now i have 51K in it's place. I guess it's eating some of the sustain and tone pulled all the way down, it's still really bassy.

    I guess i'll keep swapping it until i find the value that gives my sustain back but still keeps the squeeling away :)
    +m

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    1. Ok. Swapped that 8K2 back, and now it's ok.

      So only deviation is that 51K instead of 560K. And it sounds like 77 muff should. Verified? Can't really tell, since there is significant component change...

      Anyway. It works right and i'm happy with it.

      Thanks Mark!
      +m

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    2. Don't seem to get it. The layout seems right when compared to schematic hosted by analogguru. With that 51K it works and doesn't sound that bad, but i guess i'll need to open it up one more time and probably even build the circuit again...

      I'll let you know.
      +m

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  6. 77 Verified.

    Still don't really understand what was wrong with the first circuit. Since it sounded good, but not right enough, i decided to rebuild it. And that paid off.
    +m

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    1. Excellent, thanks mate

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    2. Hmm.. Since that 78 is essentially the same layout, with added tone switch, i guess we could call that verified too.
      +m

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    3. Yes, they've identical except for the tone bypass and I can tell by looking that that is ok, so I think you've verified both. Top man.

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  7. I'm building this currently and I'm wondering if anyone has any clipping suggestions or leads to what would work without a huge volume drop? I need to calculate forward voltage drops right? But if I make two different sets of clipping diodes on a switch have similar forward voltage drops, then they will sound similar right?

    Any suggestions? Mosfets, LEDs, germaniums? Was there anything besides 1n4148's used in the originals? NOS germs or something? What about an original quad opamp subbed for the tl074?

    Thanks a bunch mark for laying out, and mirosol for verifying! You guys rock!

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    1. It's a big muff, so it's loud no matter what you use for clipping. I used six 1N4148s and it sounds very good. 1N914 would have been my other choice.
      +m

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  8. Is this verified with the tone bypass switch? Mine's not doin anything and I cant find anything wrong.

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  9. ok, now mine is working... kinda... its getting really farty with sustain turned up and has barely any volume unless the sustain and volume are way up. The tone control at max cuts the volume out completely. I'm thinking diodes? or maybe the tone bypass circuit? any ideas? I can actually get it to sound kinda decent, but the volume is so low i dont know. i did use a 330uf cap instead of 220uf. that be it?

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    1. There has to be something wrong with the build.. Muffs are very loud and so is mine - built from this layout. The first board i did had similar issues. I just rebuilt it, because i couldn't figure out what was wrong.

      That cap is 30% higher than it should be - but it seem to be used as power filter.. I really don't know if that could cause it.

      Solder bridge? Ground continuity? Those would be a good thing to check. The usual suspects...
      +m

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    2. This comment has been removed by the author.

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  10. Damn, I didnt mean to delete that comment... wrong profile, maybe my girlfriend did.

    Anyways, I usually try my absolute best and check over my stuff at least 5 tims before posting for help. and there it was a a solder bridge... albeit in a tricky place a diagnol one under the IC where they serpentine- had a little bridge there.

    Anyways- now its sounding much, much better... got the volume and great fuzz tone... it pretty much goes from high gain to super high gain though- not much variation. The tone bypass side of the switch works. But with the tone stack enabled I'm having problems.

    When I turn the tone knob up the output gets quieter an quieter... and doesnt sound like a typical muff tone stack either. it gets less bassy more than less bassy and more trebley like a muff does... hard to describe. When its full clockwise I get no output. As I turn the tone knob down (counterclockwise) it gets louder. the tone also gets woofier and muddier... not AT ALL like my NYC muff- i know they're different, but something's wrong here.

    just wondering if the tone bypass 78 is actually verified.

    Also the small smoothing cap in parallel with the diodes is 150pf in the 77' version and 330pf in the 78 version. I dont think this is my problem, just wondering if this is intentional?

    Thanks a bunch guys!!!

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  11. It'd be cool if there was a corresponding forum for this site!

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    Replies
    1. www.diystompboxes.com is a great forum for this sorta stuff, full of very helpful folks and lots of info. I tend to use it in conjunction with this blog a lot and have had some really useful help from the members.

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  12. Yes I was thinking the same thing, although doing a blog is bad enough, I don't think I'd have the time for the extra input a forum would require.

    In answer to your question above, I did those based on Analogguru's schematics, and the 150p/330p was one of the main differences between the two. I don't know whether anyone has built the tone bypass version but the additional components needed in the 78 layout are pretty simple. Just a 150n from that IC output (pin 8 on my layout), followed by a 47K to the tone bypass switch 3, with another 47K from tone bypass switch 3 to ground. That matches the layout.

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  13. anyone verify 78' version with tone bypass switch yet?

    that bypass switch is extremely useful in live band settings!

    i cannot figure this out- the tone bypass is working, but the tone knob aint. everything has been measured and dissected... i'm thinking about just going back to the 77 version.

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  14. I took out the tone bypass circuit- replaced a ton of components and i'm still having the same problem...

    when the tone knob is all the way down I get a decent sound out of the circuit- kinda bassy- but as i turn the tone knob up the volume goes down until it's completely off.

    I'd love to see the schematic for this circuit. and since mirosol may have actually made a mistake the second time around (a mistake that landed him right) I'd like to see where this came from. short of rebuilding it, i've done everything, i would rebuild just dont have anymore vero at the moment!

    if anyone else has verified please let me know!

    Thanks!

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  15. Im building the 78 version and the board appears to be right. It no signal gets through whatsoever. I know something is amiss because as soon as I connect a battery, the 47r resistor immediately after the 9v supply gets extremely hot. What would cause this? Ground connections to the board are correct. The battery is not getting hot; I've never had an issue like this before.

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    1. My guess would be that there's a short right after that 47R. Does anything else heat up? It shouldn't get even warm under normal conditions. Can you double check the grounds?
      +m

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    2. I've been over and over the board. I've checked for bridges, checked the component values, checked the trace cuts. I can't find anything out of place and the 47r resistor is still getting very hot.

      I'm not sure what else to besides simply rebuild it like you did.

      Any trick with this board having two separate ground wires? I have them both connected to the same ground on the footswitch? Shouldn't matter right? Ground is ground.

      Delete
  16. I rebuilt the whole thing from the ground up and still have the problem with the 47r resistor getting extremely hot. The only components I reused were the IC and the 330pF and 150nF caps. I cant make any sense of it. Heres the pictures.

    http://flic.kr/p/cwBypG
    http://flic.kr/p/cwByrL
    http://flic.kr/p/cwByds
    http://flic.kr/p/cwByh9

    At this point, I'm not as much concerned that I get the circuit working as I am about what's causing this. Any help is appreciated.

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    1. I hate to nag, but if anyone has a chance to look this over, I'd appreciate it. I'd like to give it one more go before I scrap the whole thing.

      Thanks,

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    2. Measure the voltages at the IC pins and also at both sides of the 47R.

      Delete
  17. Thanks, Mark. Just to be sure, I'm doing this right. I connected one lead of my DMM to ground and used the other to get these measurements.

    Votages:
    Right side of the 47R: 7.83
    Left side of the 47R: 0.02

    IC Pins
    1: 0.00
    2: 0.00
    3: 0.01
    4: 0.02
    5: 0.00
    6: 0.03
    7: 0.03
    8: 0.00
    9: 0.00
    10: 0.00
    11: 0.00
    12: 0.01
    13: 0.00
    14: 0.00

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    1. Well you can see what the problem is straight away. The left hand side of the 47R should be pretty close in value to the right hand side so there is either a problem with the soldering or it isn't a 47R. Are you sure it isn't a 47 meg or something? Just take out the 47R completely and replace it with a copper link, it isn't necessary to get the effect working and that should show you whether the rest of the circuit is working properly. That should make a big difference, so get the IC pin measurements again after making the change if you're still having issues.

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    2. I thought the same thing. I have checked the resistor value, and if you look at it in the pictures, it is a 47R, yellow-purple-black-gold-brown. I've tried replacing the resistor with others from my bag of 200 as well to no avail. I'll try the jumper tonight and report back.

      As always, thanks for all you do on this site, Mark.

      Delete
  18. Probably a silly question but would using a 100uF cap in place of the 220uF power filter make any difference at all?
    I do have 220s but they are massive, which would make it impossible to fit in a 1590B...!

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    1. Should be ok, but you might experience more noise/oscillation in the worst case. You could try omitting it completely, and if it is too noisy without a filter cap, then add 100µ.. If that doesn't work well enough, you could try fitting two 100µs in parallel.
      +m

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    2. Thanks Mirosol, was thinking about the two 100uF's in parallel, there should be enough space to tilt them in opposite directions to save a bit in height... Will report back when I'm done!

      Delete
    3. Finished last night and works a treat, no signs of noise of buzz/hums so far... Happy days!

      Delete
  19. Stupid question, but the tone bypass switch is a SPST three-lug on/on switch, correct?

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    1. Yes mate, I should really have put that in the notes rather than make people have to work it out for themselves. I'll add it to the blog text

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    2. Hmmm. Built the 78 and it sounds fabulous. Except for when I switch the tone bypass switch. Then it completely kills the circuit. I've quadruple checked everything -- including taking an exacto to the board to cut any sneak traces -- and nothing.

      Delete
    3. Is the switch ok? I just checked it against the schematic, and it's definitely right. The junction of the 2 x 47K's to Sw3, Tone 2 to Sw1 and Volume 3 to Sw2. Then in one position the Tone control is in circuit, in the other the junction of the 2 x 47K's is connected directly to Volume 3 bypassing the Tone control.

      Delete
    4. Switch is okay. When I had it on my test rig, I was holding the volume pot -- touching the lugs -- and happened to touch the back of the board and the tone bypassed signal came up (although not as loud as it should be).

      I must have something wired incorrectly but I've checked it about 10 times and even had my wife look at it and everything appears to be wired correctly.

      Again, works perfectly except for the tone bypass setting.

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    5. Still can't get it working. Ah well, I gave up and just wired it to 77 specs. Not too bothered -- I had a BMP with Tone Wicker and I didn't use that feature much.

      This is going in a 2-for-1 box with a Triangle. Double box o' doom.

      Delete
  20. I'm having a problem with this and wondered if anyone can help. I built a 77' spec one and whilst everything works and sounds amazing, the fuzz seems very gated, so much so that playing lead is a no no. The vol fuzz and tone all work perfect and the fuzz sounds as it should except for gating. The only parts i substituted are 68k instead of 62, 5.1k instead of 5.6k, 1n914 diodes and a TL074cn chip. Cheers for any suggestions
    Dave

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    Replies
    1. Did you knife the strip gaps? There must be something wrong in there...
      +m

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    2. Ok, i tried that and also looked for any bridges using a magnifying glass, still not right. Also, when i plug the power in i seem to get a few seconds of oscillation which dies down and the guitar fades in. This is strange and annoying, i've never got a big muff to work before and this is the closest i've got.
      Thanks
      Dave

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    3. Out of interest Miro, what chip did you use in yours, im wondering if i should try a different Tl074.
      Thanks
      Dave

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    4. If i recall correctly, i used TL074 too. If you have a spare you could try that..
      +m

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    5. Cheers Miro, maybe i'll order a couple and try those. Gating is usually caused by insufficient power to the circuit or having a transistor the wrong way round, i cant understand what i could have done wrong for it still to work and sound right other than the gating issue.
      Thanks
      Dave

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  21. I'm just about to do that although i dont see any obvious bridges. It's strange that it works and sounds perfect apart from the gating.
    Thanks
    Dave

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  22. Was about to start building this. Sifted through the comments and it seems nobody has gotten their build to work yet, right? Is this thing verified?

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    1. Well, no luck. All the pots and tone switch seem to be working. But I'm getting a ton of oscillation no matter what setting the switch and knobs are set at. Tried another IC, some thing.

      I'll keep staring at this thing....

      I used 1N914 instead of 1N4148.

      Delete
    2. Oh yeah, in place of the 120nf cap, I used 100nf. Could that cause a problem?

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    3. That won't cause oscillation. For some reason my first board didn't work at all, but rebuild did. Don't have the original board as it's been some time since i built this.

      Maybe i should build another at some point.
      +m

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  23. so what is the difference between this 77 op amp and the one with 3 ICs.? most of the schems i found were the ones with 741 and 4558 amps...

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    1. sorry, what i meant was, will there be any tone difference in using a quad IC instead of the 741 and the other dual 4558..?

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    2. Yes there is a noticeable tone difference.

      Wouldn't say that one is better than the other, but definetely, they're different.

      LM741 sets a fuzzier / noisier (in the good sense) than a tl072 can offer, and the 4558 gives more colour to the tone than the TL0XX ic's.

      I've built both versions (with 4558 + 741) and the quad one, and I prefer by far the 2 IC's board, that besides is the original but, as usual, we're talking about tastes.

      BR

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    3. thanks. i did this version and it works fine.. i'd like to check out the original though.., Miro or Mark, would you guys be willing to do that layout?

      Delete
  24. came back to this circuit after a year or so. Did the 78- works when I bypass the tone circuit. when tone circuit is in it sounds good with the tone control cranked but turning it down causes major loss of volume and it becomes very muffled. I've been looking for the schematic but I cant find it! Can you not link schematics here?

    ReplyDelete
  25. Having some trouble with the 77 build. Volume and tone work perfectly but the sustain control seems to be at a fixed level of fuzz, only changing in the lowest 5% of the pot's rotation in which the signal gets cut out completely with no change in fuzz amount, and the last 5% which makes the fuzz sound extremely saturated and squishy if that makes sense. I've knifed and checked the component values and placement five or six times now and all that is right but my problem still occurs. Any ideas?

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  26. I've read quite a bit about Billy Corgan's Big Muff and am desperate to get something close to that sound. What would you guys suggest would be the best version to get there? 2x IC741 or 4558 or transistors? TL074? thanks

    ReplyDelete
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    1. i built the 2 transistor version with the the exact IC's listed on the layout, and it sounds awesome and you can get it close to the old smashing pumpkins sound. theoretically there should be no difference between the two IC version and the 1 TL074 version, as the TL074 is a quad op amp and the two IC version has two dual IC's, so either should work well for what you're looking for.

      Delete
    2. Thanks Zach, do you have a link to the 2 IC version layout, i couldn't see it on this thread.

      Delete
    3. I',m afraid to contradict my good friend Zach, but TL074 and 4558+IC741 versions sound VERY different, being the TL074 softer and less dirty.

      In my opinion, build the real thing (two opamps, en being a 4558 and 741, no way you can get this sound without this combo.

      Regards

      Delete
    4. Thanks Javi, Zach could you point me in the direction of a 2IC layout that's been verified. I've found a bunch online but they hadn't been checked.

      Delete
    5. javi, you didn't contradict me at all about it, even it you did, it's all good. i figured that theoretically it should sound the same, but being that i only build the 2 IC version, i had no idea how the single quad sounds. similar to if you replace an IC with a same model number but different suffix like TL072cn vs TL072cp.

      when i built mine i just figured better to build it like the original if i want it to sound like to original. glad to know that there is actually a difference in sound. does the TL074 version still sound good, but just different or not really close?

      more importantly i'm, glad to see you back javi. i worried something happened to you.

      and ben here's the 2 IC version:

      http://tagboardeffects.blogspot.com/2013/12/ehx-ic-big-muff-v5-78.html

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    6. Ben, you were pointed to the right direction in order to get the 2 ICs layout :)

      Zachi, I use to find little difference with different IC's on clear / modulation effects, the Deep Blue Delay is a good example, I was not able to tell between a NE5532, AD712 ot TL072.

      But if yoiu deal with dirty pedals, the sound that you get from a LM/UA741 is really different. Way dirtier and meaner than what you can get with a TL072. A 4558 it gets more colour to the tone, than a TL072.

      Being TL074 a double TL072, is easy to know that the sound would be milder. By the way, the TL074 version sounds OK, not bad at all, but was not the tone I was looking for with this pedal. Using the 2 IC's version, with the 741 is the key in my opinion.

      But the way, noproblem, thank you! Everything's ok, no health problems (had enough on 2014! :P) Now I'm just a bit busy, getting divorced and so lloking for a new home, and things like this.

      New life :P

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    7. well glad to hear no other health issues, i think we all have had enough of those this past year. i'm guessing the divorce is a good thing, so congrats.... i would gladly help you out with a place, but i am on the other side of the world. so unless you want to come to the states, not much i can do then just give support and have a beer or five for you.

      you know what, that makes sense about the IC's. it's funny, i was planning on doing a lot more IC builds and been so absorbed with Germanium and transistor builds, so i still feel like a noob when it comes to them. on all the IC builds i typically stick with the same model chips, not really try a different model so i never realized there could be that much of a tonal difference. well except when i've replaced a modern LM308 with an NOS metal can LM308h, which was massively different, thank god i have about 50 of those left. hehe

      Delete
  27. This comment has been removed by the author.

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  28. Built and boxed the 78 and love it! I've had a Little Big Muff once and sold it because I felt it sounded too artificial, but this one is meaner and more versatile. The only problem is the volume is too high too soon, even with a log pot it is very loud at 10-20%. I added the optional 100k resistor and I guess it helps, but not much. Also I'm not sure what the tone bypass tries to accomplish as it is quieter in any tone setting (not sure about mid-range), but it sounds closer to more modern fuzzes and I dig it.

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  29. hi guys,
    i was thinking about building another ic bmp so i figured i'd swing by... then i remembered this one (attached) that mictester worked up after one of my failed attempts at veroing a quad ic bmp.
    works tits. i hope IvIark and Miro don't mind me sharing it here, pretty sure it would be ok with chris too.
    i called mine the ICBM cuz... well, if you're a cold war era kid like me, icbm's were something ya learned to live with. (inter continental ballistic missiles, not cold poop ;) )

    ANYways...

    http://s605.photobucket.com/component/Download-File?file=%2Falbums%2Ftt137%2Fpinkjimiphoton%2Ffile.png

    check it out. fwiw i didn't find the clean boost to be of any value, and if memory serves the tone stack may be a little funky.
    but figured it may come in handy... mos def could use a more compact layout!! ;)
    rock on peeps \m/\m/

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