Wednesday, 11 December 2013

EHX IC Big Muff V5 '78

Javi mentioned on the original IC BMP post that the original 2 ICs instead of the quad used in that layout make the circuit sound a lot better. So i thought i'd draw up a layout for '78 tone bypass switch version with two opamps. This way one can build a clone that's closer to the original and/or try out different opamps for it. It is per Analogguru's schematic which has couple of notes on it. First of all, the sustain connections are tweaked to function better. Both can be easily be modified per original on this board. And then there's a note for 820K resistor from supply to IC2 pin 3. That resistor needs to be 1M if you want to use TL071 or similar FET opamps for IC2.




46 comments:

  1. Excellent layout matey. I'm glad you did this, I really don't like my earlier layouts at all and wanted to redo them anyway.

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    1. Thanks. It turned out a bit big, but otherwise ok. Let's just hope that it works :)
      +m

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  2. GREAT!
    But are there no cuts underneath D2 and D5?

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    1. Thanks for noticing. There should be. I'll fix it once i'm back home.
      +m

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  3. Replies
    1. The blue dots indicate double links. So for example, rows 2,7,9 and 15 are all linked. Hope that makes sense
      Cheers
      Dave

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    2. Depending on the wire that you use, you may have to enlarge the hole. I have to take the tiniest drill bit that I own, that is only slightly larger than the diameter of the hole, and drill out the opening just a tad. Be careful not to drill away the copper trace completely though.

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    3. Use resistor cut offs. You can easily get 3 in if you're using the common blue 1/4 watt MF25 metal film.

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    4. Thanks, that was what I thought. I think I never made something that uses them, so I wanted to be sure!

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  4. Built it. Rocks.

    In fact, this became instantly my favourite BMP, trumping even the Triangle, which i earlier though was the greatest of the versions. It surely sounds like a Bigg Muff, but there's something it its character that separates it from the rest. Recommended build. Definitely.
    +m

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    1. Miro, what do you think of the tone bypass mode? Is it a useful sound, or would you pretty much stick to the standard mode with the tone control?

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    2. Extremely useful. It gives you 6-9dB boost and the mids come out a lot better while still keeping the fat muffesque buzz in tact. Very good option and adds a lot of versatility.
      +m

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  5. please could somebody send me a picture of the circuit in how it is made n what parts r required a total newbee on the circuit building

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    1. You should probably try out something a bit smaller and simpler to begin with. Check the build guide http://tagboardeffects.blogspot.fi/2012/04/vero-build-guide.html
      +m

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  6. This comment has been removed by the author.

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  7. Thanks for all your job...

    Is it possible to replace the u741 uc with a LM1458??

    Thank you very much¡¡

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    1. No. 1458 is a dual opamp with completely different pinout than UA741, which is single opamp.
      +m

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  8. Forgive my ignorance, but can I use two of the u741s instead if two different op amps?

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    1. No you can't. 741 is a single opamp and 4558 is a dual opamp. The pinouts do not match.
      +m

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  9. This is probably the best muff version I've played so far. Still loving modded stuff more than original muffs :)

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  10. Hi,

    Having some trouble - can you please share what the volt readings should be at the pinouts of both ICs? Would really appreciate it. Thanks!

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  11. Hi -sorted. Amazing sound. Love it. Thanks man!

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  12. Hello Miro, which one could be a good Fet opamp for IC2?

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    1. I think i would go with TL071 or TL081.
      +m

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    2. Thank you very much Miro.

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  13. I've just built it and it sounds great, BUT, the tone control doesn't work and when I change the spdt switch position, the sound almost disappear. When changing the switch back to the original position, the problem persists, you can hardly hear it. Any ideas what may be causing this?

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  14. Has anybody built this with IC2 being something other than the UA7421?

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  15. I have done this one with a RC4558NB and a TL071 on IC2. Sounds great! A Little bit sag sound. I put a buffer in front of him and works great too.

    photos: https://www.flickr.com/photos/77206179@N02/sets/72157648864378317/

    Anyone else have this sag-velcro sound? My settings are sustain all the way up, tone one o'clock and volumen 2-3 o'clock.

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  16. I ordered some op amps from Mouser to try and build this. I have an RC4558IP and UA741CP. I'm not sure if the prefixes and suffixes matter or not. Will these op amps work? Fingers crossed. Navigating Mouser's catalog is a bit daunting for neophytes like myself! The 1/4w resistors I ordered are all pretty huge too, so in some places I'm gonna have to mount them upright.

    I'm also wondering how I'd build this without the tone bypass switch. I assume just a jumper in place of the switch, but would it be between rows 3 and 9 or rows 9 and 11? Or is there a simpler way still if I'm omitting the tone bypass? I'd like to incorporate it, but with the graphic layout I have planned the only way I could see it fitting would be possibly on the side of the enclosure. Hmmm.

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    1. One more question. Which way would the op amps orient? Should I be able to read the text on the op amp upright as viewed from the left side of the board or from the right side?

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    2. First, just leave the switch wires out and connect tone 2 straight to volume 3. That would be the simplest way to go.

      Those ICs will work fine. The prefix usually indicates the manufacturer (the same chips have been produced by a number of different brands) and the suffiz usually indicated the packaging the chips were shipped out in. So basically those don't matter at all.

      If you look at the layout, there is a lighter grey recessed marking on the top side of each opamp. You should have similar recessed dent on your opamps.
      +m

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  17. According to images over at kitrae of actual units, the 330p capacitor is usually 160J or 150J which is 16p 5% or 15p 5% ... one of those pepetuated bad schema deals.

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    1. from the schematics i looked at you are correct. one thing to keep in mind though that this is a feedback resistor. the larger that cap is it will smooth out the clipping, and rolls off some of the highs, and get some more bottom end. if you lower it you'll get more "crunch", and less low end. you can play with different values and see what you want to do. i personally built mine as the layout is and it's perfect. it's a little smoother, and bassier then some of the videos i've heard of the 77 op amp. i think it's much, much better.

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  18. How would be able to add a mid control on this? I know on the Russian you replace the C1 with a 22nf and change the R2 with a 22k and resistor in series. But I can't find a stock IC schematic to compare.

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  19. Is it normal that the high notes sound a little bit 'gated' and less clear/more silent? I had it first build with the tone switch, but no sound came trough with the tone bypassed.
    With a boost in front (SD1) the higher notes are a lot clearer, so maybe a gain stage problem?

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  20. Try a buffer before the muff.

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  21. I don't know if this gets read, but.. What is the function of the 120nf cap between the tone and volume? I don't have one right now and am not sure if the 100n or 150n would be a better substitute.. I changed the ceramic to a 15pf and the volume to a 100k but was wondering what a better sub would be in this case.. Or order one

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    1. That cat is from tone 1 to ground and it's a part of the tone stack. With cap subs, i'd say it's always better to go up rather than down - unless you want the circuit to sound thinner. 150n will be just fine.

      For Svein and zosotone - haven't seen this behaviour with mine.. Are your diodes ok? Are you using 741 for the IC2?
      +m

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  22. Yes, my 4148's are ok and I used a UA741 for the IC2.

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    1. That seems rather strange to me as i've built a few of these and the behaviour is new to me. And i can't explain it straight away...
      +m

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