Thursday, 14 June 2012

T-Rex Mudhoney


Info about the original:

Mark Sullivan from daddys.com wrote this

The Mudhoney is a Distortion/Fuzz pedal with a very wide tonal range. It features a typical 3-knob gain/volume/tone layout plus a boost switch. I played this for a few minutes with the boost off and it is quite impressive; very thick tone with warmth that could quickly find its way to being your main dirt for jazz, blues, etc. Then I pushed the boost and cranked up the gain! The speakers in my little Princeton cried for mercy. Hitting it with the bridge pickup of a Les Paul brought sustain of Spinal Tap proportions. Chords were a menacing wall of sound but yet unlike its name would imply, the Mudhoney didn’t get muddy and muffled. Note and harmonic separation was impressive giving a very dimensional sound at gain levels where most pedals sound flat.
 

Features

This baby is designed for those who want an in-your-face wall of guitar sound jumping of the speakers.

The boost button and the tone knob enable you to dial in every sound you like right from ultra fuzz to smooth jazz sounds.

In "OFF-MODE" (with the boost-function bypassed) the Mudhoney delivers moderate gain and a smooth rich sound favoured by many jazz-guitarists.
For a more hairy sound, -just hit that "boost-button" and feel the rumble from hell.

The BOOST button switches between moderate- and high gain.

The GAIN knob controls the distortion amount.

The LEVEL knob sets the overall volume
In mid-position (twelve o’clock) the volume level is 1:1. When turned full over (clockwise) the input signal is boosted 15dB.

The TONE knob affects the top end (edge) of your signal without compromising sonic quality, allowing you to dial in the perfect tonal flavour for you taste.






64 comments:

  1. Sweet.. thanks for this man. Will probably get it built up next week after pay day.

    ReplyDelete
  2. Built this today, i had neither a bc546 nor an op07cp (both been ordered) subbed in a bc547 and an lm308 and it works a treat so i guess you can say the circuit is verified, though obviously with the subs it will not be identical to the original. However the subs have still made it a really good pedal, deffo a keeper. Played around with the diodes too and i think i`ll opt for a switch with 1n60p`s and a pair of red led`s. Will build another board for a stock circuit when the parts arrive...... or maybe not as i`m very happy with what i got. Thanks for another great layout.

    ReplyDelete
    Replies
    1. Have you modified anything on the layout?
      I have built it, and it is not working.

      Delete
    2. No it hasn't been altered since it was verified

      Delete
  3. That's great, thanks for verifying. 5 to go!

    ReplyDelete
  4. I assume it would be ok to use a 47p capacitor instead of the 33p going from pin 8 of the ic? I just don't have a 33p on hand.

    ReplyDelete
  5. I've got a few questions. For some reason I am only getting a 1:1 volume when the level is all the way up. I did use a 1uf ceramic rather than a 1uf radial. Could that be the reason? also when the boost is on the gain seems to go from nothing to crazy with very little movement of the gain pot.

    ReplyDelete
    Replies
    1. Also, I am getting some loud popping when I turn it on and off even though I have grounded the input.

      Delete
    2. No 1u ceramic should be fine so something must be amiss elsewhere. Look for any dodgy solder joints and reflow if necessary. LEDs can often cause popping too, so if you've included a pulldown resistor which should sort it in terms of the effect input, then it will more than likely be the LED. Have a look at this:

      http://www.muzique.com/lab/led.htm

      Delete
    3. So I've replaced the LED, and swapped the 3pdt switch out once (first one broke) this second one is giving me some trouble to, not switching back ti true bypass, just going silent. And I'm still getting the loud POP! Could it be the 3pdt switch? or does it have something to do with the high gain circuit?

      Delete
    4. Also I even just unhooked the LED to see if that would solve it and I was still getting the POP

      Delete
  6. Has anyone tried a lm308 in this thing? It makes for a better chip in the rat so what about here?

    ReplyDelete
  7. Something has gone horribly awry here, Mark. Chip would need to be on copper side, as mirror image shown. D'oh!

    ReplyDelete
  8. That bc456b is PNP correct? Think I could get away with a 2n3906?

    ReplyDelete
    Replies
    1. It says BC546B and it's NPN. The 2N3904 should be ok if you have them

      Delete
  9. Herp derp. hahah, I need to sleep. Stop posting so many layouts! lol

    ReplyDelete
    Replies
    1. Ha ha, you're just like my wife, it's always my fault! :o)

      Delete
  10. Is it the 2.2 that controls the gain of the IC?

    ReplyDelete
    Replies
    1. No the gain pot controls the gain of the IC. the 150R sets the minimum gain and the pot value sets the maximum.

      Delete
  11. Well, the only change I made was using a 3.3k instead of 2.2, now if I understand properly, that means that i've changed the corner frequency of that rc filter. The mode without the boost is MUCH lower gain than the clips, and that's the only change I've made.

    ReplyDelete
  12. Just having some trouble with this one, but I guess this is more of a general troubleshooting question. When using an audio probe if I touch the output (from the level pot) I can hear the effect OK and it all seems to work correctly. If I put it on my test rig, I don't hear any output at all from the effect. At first I thought my test rig must be faulty so I tried an effect I know that works on it, and it worked fine(!) so the test rig must be good. The only difference I can think of is that the audio probe is attached to ground, so does this mean I have a problem with the ground part of the board?

    ReplyDelete
  13. The sound is close to the original? I found a schematic and it's different from this. Removing te Buffer, there are some components missing in this layout.

    ReplyDelete
    Replies
    1. Post a link to the schematic. The scheme for this was traced by a member of freestompboxes.

      Delete
  14. OK so I rebuilt the effect from scratch with all new parts... I get exactly the same problem. When I touch the audio probe on the pedal output it works perfectly. All the controls function as they should and the effect works fine. However without the probe when boxed up I get nada. Am I missing something obvious here, this is driving me crazy! Any help/suggestions much appreciated!

    ReplyDelete
    Replies
    1. P.S. the pedal works fine when bypassed so I'm sure all the off-board wiring / jacks are sound.

      Delete
    2. Are all your grounds connected together? Board, I/O sockets, DC adapter, switch?

      Delete
    3. Yes all grounds are connected together, pics to follow shortly. Even when i attach the audio probe without the ground at least i hear a buzzing rather than nothing at all... what's the best way to test the ground from the board is working?

      Delete
    4. Just check for continuity between all points of ground. As long as there is continuity between them all it should be fine.

      Delete
    5. OK all points of ground pass the continuity test, if I put a probe on the ground output of the board that's fine too. The whole bottom row of the board passes the test. Anything else other than grounding that could be causing this?

      Heres some pics of the wiring https://plus.google.com/photos/116241861790572354815/albums/5851159051084585457

      So just to recap:

      - It works fine bypassed
      - The LED lights when I engage the effect
      - When I engage the pedal I can hear the effect working OK with an audio probe on the output jack.

      Thanks again for the assistance, really appreciate it. So weird cause I've build about 15 of your layouts so far and had only a couple of minor issues, this one just wont play ball!

      Delete
    6. Anyone got any ideas on whats wrong? Help!

      Delete
    7. If you can hear the effect working ok with an audio probe on the output wire, but not when you have a cable in the socket to your amp then it suggests that something is wrong with the socket. You haven't got something shorting against the tip have you?

      Delete
  15. Here is the schematic that I've found on the web.
    I don't know if it's correct or no. It was just an opinión, if your scheme was traced by a member of freestompboxes, I'm totally sure it's close to the original. Thank you.

    http://guitar-gear.ru/articles/TRex/TRex_Mudhoney_sh.GIF

    ReplyDelete
    Replies
    1. The schemes look fairly similar, they're both obviously modified Rats and it could be that they were both traced from different versions of the pedal which would account for the variation in some of the values. Also bear in mind that the scheme you posted shows all the switching components which have been omitted in this layout in favour of our usual 3PDT stomp switching. So the 4013 IC and related components including the bypass buffers aren't required.

      Delete
  16. OK so it gets weirder...I was messing about with the ground connections, all fine. I changed the output jack, no change. It still worked with the audio probe, and I noticed that the only difference between that and the output jack in the box was the 100n greenie cap that was attached to the probe. I soldered the cap between the output from the 3DPDT and the output jack, and hey presto. What would the cap be doing that would make it start working?

    So its boxed and working, however I've still got a few issues that suggest something definitely isn't quite right. The tone knob seems to be reversed, is that correct for this build? (I.e. it gets brighter when turned to the left, darker to the right).
    When the treble and gain are turned up in boost mode i get a shrill high pitched noise...
    In non-boost mode the gain is a lot lower than in the mudhoney demo video.

    I've got another mudhoney circuit that was having the same issues so I'll try that with a cap on the output to see if it solves it. On concern I've got is that when the effect is bypassed the signal will be going through the cap...will this affect it? I guess i could put the cap between the board output and the switch input...

    I've put some more pics up of what I've done in case my ramblings don't make sense...

    https://plus.google.com/photos/116241861790572354815/albums/5851159051084585457

    Thanks
    Jack

    ReplyDelete
  17. I just built this again from scratch will all new components and there is definitely something wrong with the layout.

    It only works with a cap on the output.

    ReplyDelete
    Replies
    1. I do believe you're correct. The schematic shows that the Level 1 is connected to vref like in the layout - but - the switching buffers have been omitted, so the level control just simply won't work as it is in the layout. You're getting vref to the Level pot and passing that on to your amp..

      Take the Level 1 to groung strip instead of vref where it is now. You should be golden with that...
      +m

      Delete
    2. That won't cause a problem. Vref is a virtual ground and acts in exactly the same way as real ground, it's just somewhere the signal can be dumped to.

      Delete
    3. Hmm.. Weird. There still is 4.5V on that rail. In my understanding it would still need a cap after volume 2, if the pot mixed signal with output and 4,5V - As that would have the signal and 4,5V pushing towards the amp..

      I believe Jack got his working once he took volume 1 to ground...
      +m

      Delete
    4. I see what you're saying about it and dumping to ground always seems to makes more sense to me and . I'll alter the layout to use ground, but I'm interested how dexxxy's worked ok, unless he assumed the Vol 1 connection dumped to ground maybe? Thinking about it there will always be DC there without a cap.

      Delete
    5. It is common practice to use vref virtual ground for dump at volume control, but that's always followed by a buffer or electronic switch setup. A few designs use vref, and simply have one more cap after the pot. Noticed this with Marshall Blues Breaker just today (planning to build one soon).

      While IC sees the vref as virtual ground, the amp doesn't see it as nothing more but 4.5V DC:)

      In Dexxy's case, i would assume that he just grabbed vol 1 from the bottom row without thinking about it:)

      Hope your trip was good and welcome back!
      +m

      Delete
  18. i'm trying to do this effect but where is connected switch3?

    ReplyDelete
    Replies
    1. It's not connected anywhere. It's just an on/off switch, in one switch position you close the circuit, in another it stays open (wires disconnected/not connected to each other).

      Delete
    2. Alright, my comment just disappeared?

      Anyhoo... it's not connected anywhere as it is a simple on/off switch. The wires are either connected or disconnected, second throw does nothing except keeps wires disconnected.

      Delete
    3. No connection. A SPST switch will do the job but they are less common in those mini toggles and when I have seen them they were more expensive than the SPDT switches, so you may as well just use the SPDT you're more likely to have in stock as shown, and only use one of the throws.

      Delete
    4. Something is happening to this thread. I've answered this question twice and every time it dropped my entry. Some sort of blog limitation?

      Delete
    5. Not that I'm aware of mate. The only problem I know of is the 200 comment limit which can be a pain

      Delete
  19. Maby I'm stupid, but exactly how do I connect the switches to the board?

    Is it like I think...? Standard 3PDT switch with IN and OUT (from volume pot) and the boost switch pin 1 and 2 to the board where it says "Sw1" and "Sw2"?

    ReplyDelete
  20. Sounds great and very much like the original I used to have but the sweep of the gain pot is just crazy. Jumps from almost nothing to almost full blast right at the beginning. Gonna try a log pot there.

    ReplyDelete
    Replies
    1. Ok, I put a 100k log in there, now the taper is near perfect. Definitely worth trying.

      Delete
  21. Hello, can you help me?
    my:
    Q1 C:6v B:1,35v E:1,77v
    Q2: D: 6v, S: 1,5v, G: 1,7mV
    its correct?

    ReplyDelete
    Replies
    1. Being Q1 collector and Q2 drain directly or linked to the +9v rail, I'm afraid that something's wrong. Id check the 100ohms resistor value or the solders in this rail.

      BR

      Delete
    2. i replaced the 100ohms ressitor to real 100ohm, and now the Q1 c:5,48v Q2 d: 5,48v
      but still not sound

      Delete
  22. Anyone tried this out on bass?

    ReplyDelete
    Replies
    1. I just had a play on a real one, decided to check out the layout. One thing i noticed was that the tone knob just rolled off treble, wasn't one of those more bass or more treble knobs. And anything under say 3 o'clock was not nice. So maybe if change some cap values (not fully sure which caps) or make a buffered blend? It could add some mad growl whilst you keep your bottom end.

      Delete
  23. Can't seem to get this one to work, bypass works and the LED works but when I turn it on, no sound whatsoever. Any idea what I could try to find the problem?

    ReplyDelete
    Replies
    1. Measure the DC voltage between all transistor and IC pins and ground. That should give a good idea where the problem is

      Delete
  24. I used to run a little green wonder before this just to get a fat ass lower mid boost. I think I'm going to shoot for a modded version to achieve that sound with the mudhoney alone. Any ideas on how to approach that? I think I'm gonna start with just upping the input cap 'cause I run the gain at about 12 o'clock and it starts to get fat only after that. I have an idea of what components to play with but if anyone has a better understanding of how this circuit works, help is appreciated!

    ReplyDelete
    Replies
    1. Increasing the input cap may help and so it's always worth trying, but you'll get more of an affect by altering the high pass filter at the inverting input. As standard there's a 2K2 and a 100n to ground which gives a cutoff frequency of around 723hz, and so you might want to try something like a 220n which will drop that cutoff frequency to 328hz meaning you'll be getting no attenuation between 328 to 723hz, which is right around the lower mids frequencies.

      Delete
    2. That's pretty much where I was looking at but thank you VERY much for the specifics, I'm not too familiar with the math. Also thinking of playing with the tone stack.

      Delete
  25. Hi,

    I build this one and it sounds very good! thx!

    Everything works normal but, is it possible that I get noise comming true when my guitar is plugged in?

    Thx

    ReplyDelete
  26. Having some troubles and I'm not sure if it's how the pedal is supposed to sound or if there is something wrong. If something is wrong all the things may be related I think:

    First, difference between normal and boost is MASSIVE, when gain and volume are at 12o clock my overdrive sound is quieter than my bypassed sound, this same setting on boosted results in full on fuzz (sounds good though).
    Normal mode also doesn't have a lot of bass to my ears...

    Second, on boosted the gain really doesn't add anything more above 12 o clock, all drive seems to happen before that.

    Third, my tone control works backwards, counter clockwise results in more treble...

    Any Ideas?

    Thanks !

    ReplyDelete
  27. With the gain all the way up, my build is self oscillating when in boost mode, but just with the guitar plugged in. When I disconect the cable, the noise stops. Any ideas?

    ReplyDelete