Friday, 18 January 2013

Runoffgroove Umble

As. Requested. Info from ROG: There has always been much talk about the mystical hand-built amps that a particular man sells for around $10,000 each. Some claim these are the greatest amplifiers known to man, while others maintain it's all hype. The runoffgroove.com team doesn't know for sure, because neither of us can plunk down 10 Gs on an amp! We've heard the Line 6 digital models of the amps. One of us owns the Behringer unit that has another digital model of these amps. Between the two of us, we also have several recordings of these elusive amps.

After some prodding by a member of Aron's Stompbox Forum, we decided to investigate and try to make a FET-based stompbox from one of these amps. There aren't many schematics available and those are subject to debate regarding their authenticity. Putting all that aside, we set out to distill the available information and come up with a circuit that was, at the very least, heavily influenced by the amps. We opted for the preamp section only, since the "precision power amp" is intended to be clean and not readily distort. We decided to omit that section for simplicity's sake.

We named our resulting circuit Umble. Looking closely, we can see what amounts to a few Fender-style gain stages and an odd looking Fender-style tone stack. There is nothing revolutionary about the cascaded gain stages, but the tone stack looks like it was mis-drawn. Maybe this was a "happy accident" by the designer, but this little variation from the Fender design has a larger impact on the sound and is perhaps key to the $10k sound. The controls become more effective and change the overall sound of the circuit in comparison to the standard Fender unit. One can also notice odd interactions of the three tones. In our research, we have read many accounts of the actual amps that back-up this effect.

A breakdown of the Umble circuit will reveal a conglomeration of several schematics available on the internet (see the Dumble Amps section of Schematic Heaven for a nice assortment). We used the gain stages from the '70s ODS model and the tone stack from the front section of the '97 ODS model. We eliminated many of the large resistors and small caps that didn't have much affect on the tone, but increased the noise level somewhat. We also left out all the complex switching options and hard-wired a straight-ahead sound.

We don't really know if it sounds like the amps SRV, Eric Johnson, Larry Carlton, etc. used. There are elements in the sound that are similar to some of these artists, though. We think the Umble sounds much smoother and more like the famous recordings than the Behringer or Line 6 models, but that may be personal preferences. There is some background hiss, but not an intolerable level.

With the real amps, it's hard to say what the definitive sound is supposed to be. Since each one is custom made, the amp sounds could be very different from unit to unit, even though they have the same model name. Our advice is to try the Umble as it is drawn. If you think you would like something a little different, "customize" this circuit after looking at the amp schematics.

Here's Geiri's demo with the build he finished using the layout below. Thanks Geiri for your work!


 



54 comments:

  1. Yummy, no crystal lettuce in this crystal lettuce.

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  2. A very good one indeed. Excellent overdrive/distortion and can do great creamy fuzz too. Works magic with single coils by giving a very unique tone with rich harmonics. I wanted a lower gain option for more versatility so I discussed it with the guys at ROG and they suggested a switch for bypassing the first gain stage. Did it and it was great, especially for humbuckers.

    Super build.

    http://fuzzquest.blogspot.co.il/2012/10/tumble-and-drive-rouge-dumble.html

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  3. If I may inquire, where and how was the switch placed? SPDT between 22K and Gate?
    Thanks, Pete

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    1. What switch, do you mean the main bypass stomp switch?

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    2. Sorry, thought it was clear in the order of posts. From the Doron Barness post above, "I wanted a lower gain option for more versatility so I discussed it with the guys at ROG and they suggested a switch for bypassing the first gain stage. Did it and it was great, especially for humbuckers." I can see a switch on his build from his site, but do not see (or comprehend) where it would go in the circuit, my guess was a SPDT between the 22K resistor and the and Gate of J201 at 3x7? Just starting on the Trim pots, and then the eCaps.

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    3. If one wants to bypass the first gain stage.. I'd use SPDT on-on switch - Take the input to pin 2, pin 1 to board's original input and pin three to Drain.. But i'm not sure if that will work properly, as you'll be getting DC voltage to your pickups through that stage's trimmer. You'll probably need a cap, something like 100n between sw lug 3 and the Drain...
      +m

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  4. Makes sense. I was looking at the wrong side of the transistor. I will add a single socket at board holes 1,1 and 1,9, and include a 100n from SW1-3. Question: Is connecting at 1,11 possible to bypass the trim pot entirely, or does it bypass too many other components. Sorry for the dumb questions. Relatively new to pedal building and a ditz when it comes to understanding circuits with any level of comprehension. -pete

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    1. The tone section will eat up a lot of the signal strenght without that first gain stage.. You could just try to bypass that altogether and take the input from switch to volume lug 2..

      Or you could wait until Doron sees these messages and lets us know how he did it :)
      +m

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    2. I elected not to wait and went to his blog and posted the question. This was his reply.
      Just lift the (-) of the cap from the ground row. You should notice, if you do it while you play, a decrease in gain. It's not a huge difference but it's enough to get you cleaner tones from humbuckers and hot pickups on the lower gain settings. You can do it with many of the ROG designs. It is super useful.
      It was also requested that ROG be given due credit (Make sure you credit ROG for the mod as it was suggested by them.) and so it is written, so it is done.
      I have wired it in but am waiting on several components to complete and test. Thanks

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    3. Hey Everybody,

      Just opened my Umble pedal again to make sure I was right. I also discussed this a month ago with Brian of ROG who is a super nice and patient guy. I just did what he suggested after I mentioned that the Umble which I love so much is too dirty on lower settings and I wanted to get a mod which would make it comparable to the gain switch on the "Velvet Pedals" Umble. If you check out Velvet Pedals, you'll notice they have ROG designed pedals with extra gain switches. Now the guys at ROG don't know exactly what the Velvet guys did to their designs but they assumed it's a gain stage mod and they suggested I try it. It's just lifting the 4u7 cap from the source of the FET on the first or second stage. I tried it on both and it is exactly what I wanted. I implemented a switch on my pedal for removing the cap (by lifting the (-) side from the ground with a SPST) on the first gain stage and I was happy. No change in sound or in character, just little less gain. Very good Fendery sound. I am going to do the same on the English Channel by ROG. If you really want a more fendery 5E3 sound, go for the Azabache, it's amazing.
      Good luck!

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  5. Just finished a cardboard build and am experiencing a bit of fizzle at certain spots in the volume pot. thought it was related to the treble setting, but not sure. replaced the pot, no improvement. trannies are biased and everything seemingly works, great boost with the master, distortion with the volume, and T, M, & B seem to work. Any thoughts? Its late and I will scour the backside for possible shorts, but it sounds like it may be a bad cap. Just don't have the knowledge or experience to know the possible likely cause.

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    1. The small ones (47p, 330p)are likely suspects, as those are to smooth unwanted noise. But it works? So should it be tagged?
      +m

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  6. I would like to say yes, but I have not figured out what it is doing and why. I changed the treble and volume pots, not change. I changed the 47p and 330p at volume 2&3, no change. Swapped out three of four Fairchild J201 for three IFC J201 (only had three), which required a big change in TR settings to re-adjust bias to 4.5vish. Verified correct positioning of all components, check solder joints , and no bridges. At certain spots in the volume and treble pots (varies with the settings of the volume and master, and sometimes the treble), the fizzle sounds like and old philco radio trying to tune in a distant weak station, but is just static. The band(s) in which it occurs is very narrow. it's like it is moving through stages as the resistance increases or decrease, which is why I tried swapping trannies thinking maybe the voltage is varying somehow. May need to be in a case for proper shielding and grounding. I did incorporate the mod from Doron, but that has had no effect either way that I can see. Other than that, yes, it works.

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    1. Fizzle/static...maybe a bad or dirty pot(s)? I've had weird issues before and changed a pot and the issue was corrected. Just a thought.

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    2. Just finished this and am experiencing exactly the same problems as Pete at the vol pot. There seems to be just one tiny sweet spot- so really acting as a trimmer, really. Done all the above checks too but no luck so far. I will persevere, however, because this does sound good at this sweet spot; anyone familiar with " Room 335" by Larry Carlton will have an idea of the type of sounds this can produce. Anyway, somebody pass me my white trousers I'm putting down my soldering iron and picking up my axe :D

      Mark

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    3. This comment has been removed by the author.

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    4. I've been the layout through a few times and i can't see anything special.
      -Volume 1 connects to ground. It is true, that the source of right upper J201 connect to ground through 1K5 and 4µ7. All the ground connections connect to the same ground.
      -Volume 3 connects to Treble 2 and 47p that connects to volume 2.
      -Volume 2 connects to 220K+330p (going to gate) and 47p (going to vol3)

      I still can't see anything that differs from the schematic... Mark?
      +m

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    5. I just deleted my last comment because I realized what you just pointed out - all ground connections connect to same ground. So in effect, that volume lug is connect to all the transistor sources.

      I'll go ahead and build and see if it is any different.

      Thanks

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    6. Just gave it a quick once over and it looks ok to me

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    7. Yup. Pretty much same here. I wasn't 100% on this, because the tonestack was a pain to put together.. :)
      +m

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    8. Hello guys, me again from the land down UMBLE. After going over and over and over the circuit and layout, I am still at a loss to determine why the pots act the way they do. I went so far as to make a second board with all new components (not that my first build used old components) I simply started from scratch. I did not have 4 J201's, used MPF102 instead. I did not have an A500k for Bass, and opted for a C500k, seems to pronounce Bass with CW rotation a little better than A500K (subjective). While the circuit basically works, there are still issues with pots during rotation and depending on where other pots are set. I am still experiencing the severe distortion, static, radio type interference (no stations yet but very bad) and at the extreme end of rotation, severe shrill, occurs with volume and master, also occurs with treble, mid and bass depending on volume level. Another way to describe what is happening, is when the volume and master are set at half, and say the bass is full on, when you rotate the treble, you hit a point in the rotation where it is almost like a gate closes (or opens, then as you continue rotation, a second point where it opens or closes again. this phenomena is interchangeable between the pots and depends on which is set where.
      For your consideration, when I built the Box of Rock (thank you for that layout as well), I experienced a similar issue on final build, as I was taking certain ground connections from the pots with grounds, which resulted in several of the pots not working at all or producing strange results when rotated. Once I moved the ground connections back to the common board source of the (-) power source, all was well. I am wondering in the case of the UMBLE, if the way everything is directed to ground on the board is having this similar effect. I have little to no schematic training, knowledge or experience, but I am able to follow this layout to the schematic posted on the ROG site. My lack of understanding of electronics, signal paths, OHM's law, etc., prevents me from making any sort of amicable suggestion, but I am curious as to how the signal path(s) (audio and power) travels in the schematic versus the layout. I am sure there is a law that says it is fine, but based on my experience with BOR, maybe there is something that was overlooked. I would not know how to begin changing ground connections if this is part of the issue, but it seems that there is a problem somewhere in the grounding and the way the pots are interconnected via the grounds. (out of the mouths of babes.)
      Thank you (and Mark) in advance for any additional help.
      BTW - Mirosol: I found the Catlinbread Pareidolia on the Sabro site as you suggested. Cardboard build works great, going in a case today. It's for my son, and apparently, one cannot have too many pedals with tremolo, vibrato or variations thereof.

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    9. Pete

      I just got the board cut yesterday for this and was going to start populating components today ( I am a slow builder - I envy you guys who throw these things together in a couple of hours ). I'll tell you what - just for the sake of comparison, I am going to build the vero layout that someone posted at FSB. ( http://www.freestompboxes.org/viewtopic.php?f=13&t=16811&p=186574&hilit=umble#p186574 ). If it does the same thing, we'll be more sure that it is just a quirk of the pedal. Might take me a few days to get it done....

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    10. Tim,
      I considered doing something similar with the ROG schematic, but wanted some feedback before going down that road. Plus that, I am running out of certain components, like pots and trim pots and 4.7 caps. I saw your earlier posts, did you build this one? Going over to FSB to have a look at your link. look forward to seeing how your build turns out.

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    11. Haven't built this layout yet - was getting ready to as in my previous post - vero all ready for components, but I just happened to be reading through some assorted comments ( one of my favorite things to do here besides build...) and saw your most recent one. Since you have built a second one, and still get the same results, I just want to try the other layout to see if it does the same thing. If it doesn't, then you may have a bad run of some particular component - or really any number of things. I just want to see if that stuff you experience is something that is just part of the pedal. I don't think it is because I've watched a couple of youtube vids of this pedal and haven't seen that happen. Mark and Miro have re-checked this layout twice, so I trust that it is correct. I just want to see if the other acts similarly.

      Anyway, I really want this pedal and was very jazzed to see it show up in the layouts. You will have to have an account at FSB to download that layout ( pdf format ). Give me a few days to finish the build and I'll report back ( so slow - I keep too many irons in the fire...).

      Thanks Pete.

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    12. Tim,
      Too late, I already have the PDF and am starting to do a layout. While, Mark and Mirosol do a fantastic job, I am seeing what might be differences between the vero and the ROG schematic and now this second layout. Might just be intrepretation. As stated earlier, i simply do not understand enough of this stuff to even make such a comment. As for the components, the second build was intended to weed out that possibility. I used pots from two different batches, (one set is soldered lug, the first set are PCB mounted. Just so you know, when I get to the spots where the pots are not static or radio station tuners, the sound is incredible, bright, clean, nice.
      I'll be looking for your post. BTW, the FSB post and pictures look promising, fingers crossed.

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    13. I'd be interested to hear the results too as i'm pretty confident about the layout. Should probably build it myself too just to be sure..
      +m

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    14. Cool. It's a race to the finish then. I believe you will beat me to it :)

      Yeah, there is a lot I still don't understand completely, but I'm getting more knowledge from build to build. I can usually at least tweak the tone portion of the circuit to my liking now. It's pretty cool when the lights come on and you have an epiphany on some aspect of the circuits.

      Look forward to hearing what happens with the current build ( if you beat me to it - you will...). I just finished getting all the cuts, links, and trimmers in place. Components next....

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    15. I'm a bit of a noob and my deeper understanding of electronics is frankly rubbish but I had a encountered a not too disimilar problem last year building the Mad Bean " Boneyard". From what I gathered on the forum there, Brian put part of the problem down to the proximity of a couple of components. This was resolved by soldering a resistor to the underside of the pcb. Maybe I'm talking out of my arse but I've been over the layout over and over again and it faultless as far as I can see. So, if we are all getting the same problem maybe it something to consider rejigging the layout. if it's not that then I've just bought a shed load of dodgy pots! I'm really interested on how you both get all get on coz I'm dying to nail this one. Good luck chaps! :D

      Mark

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    16. Good news and bad news. Bad news, the layout from here works but has issues as previously noted. Admitting my shortcomings in this area is a given, however two builds with the same results? The good news (as it is) the FSB vero layout referenced above does work, as of 01:12 EST. Bad News, I live in a condo and my neighbors would not likely appreciate a full on test. I do notice that when i touch the volume pot, I am grounding and creating a level of static and hum. I suspect that will disappear once it is in a case, hopefully. here are a couple of links to each layout.

      TBE Layout Build:
      http://i786.photobucket.com/albums/yy144/petevig/IMG_2022.jpg
      http://i786.photobucket.com/albums/yy144/petevig/IMG_2023.jpg

      FSB Layout Build:
      http://i786.photobucket.com/albums/yy144/petevig/IMG_2025.jpg
      http://i786.photobucket.com/albums/yy144/petevig/IMG_2026.jpg

      Will post later today once I plug it in a strum a few bars.
      pete

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    17. Really weird.
      I'll see if i can build this myself this week...
      +m

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    18. Nice one, Pete. Good job on the board mounted pots. I'll probably have mine completed later this week since you have confirmed this one. Wind it up once the neighbors are out ( I live in a condo as well - have to keep it down to a low roar...)!

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    19. Tim,
      don't forget the 47p across Vol 2/3 lugs, was omitted from the FSB layout, but referenced in his subsequent post, as was a reminder for the bias settings.
      Fired up the amp, SOUNDS GREAT! The Treble and Mid seem a little weak, (will double check my wiring), but the bass is well pronounced. Nice tone when you lower the Vol and bring up the Master, and even better vice versa. Found a youtube comparison between an Umble and a Katana. Aside from the guitar playing (which is phenomenal) both were set to 12 and both sound pretty darn good. I like the Umble better. Now if only there were a pedal that would make me play like that.

      Mirosol,
      I hope your build reveals where I went wrong, as I am hopeful I can salvage the TBE build. I kept my second build intact but had to salvage a number of components from the first in order to complete the FSB. Playing with it again today, it seems like the pots are fighting each other as you rotate, if that is any help.

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    20. Pete

      Thanks for that reminder about the 47p. I would have forgotten about that. Did you set all the trims for ~4.5V on drains? So when you compare it to the Katana ( which I think is a boost ), is this an overdrive, or a boost? Does it add distortion/overdrive?

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    21. I set the bias first with a battery, and then with my 9v PS. pretty sensitive , but I was able to get all at 4.5-4.56v. With the MV on low, and the volume at 9-12, there is distortion,. nice distortion, similar to other circuits using J201s. With the volume barely cracked and the MV dimed, you get nice, bright (not quite clean) tone on the middle and neck. (I have a home built strat with SC,SC and HB on the bridge.
      Here is a link to the Katana comparison. The reviewer describes the Katana as a little darker, use for jazz and fusion, Umble for rock and blues.
      http://www.youtube.com/watch?v=oTZuud43sEM
      Click on his name to see a video. or this link
      http://www.youtube.com/user/cheesyplay3000?feature=watch

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    22. Cool. That is the demo that I had seen previously. Look forward to getting mine done.

      Thanks

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    23. Mirosol,
      Layout is verified, at least for my build. It was poor troubleshooting on my part and the 47nF in the upper left corner. I had replaced it once with the same results using another box type from the same batch. Went back tonight and changed it out again, this time for a brown one and viola, it works. My apologies and keep up the good work.

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    24. Don't worry. Plus Geiri built it a few days ago successfully. Just glad to hear you got it sorted!
      +m

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    25. Excellent news, Pete! A-debugging I shall go :-)

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    26. That is great news. This is a much more compact layout. Thanks for this one, Mirosol!

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    27. Oh yeah, oh yeah, oh yeah! Switched the jfets to the 2n5458s used in the ROG Thor and it fired first time, albeit as a slightly over-engineered cleanish boost! The good news is, as reported above the layout definitely works; the bad news, I do a have quite a few Bad J201s in my stash :-(

      ...and then like a miracle, the postman delivered a long forgotten Tayda order through the door! Put in new J201s and....WOW! Odin bringer of Jfets is on my side or I'm getting some good karma back (someone had to help those old dears across the road)!

      Anyway, Pete, your persistance on getting this thingy working has urged me on so cheers to you and Miro! this is superb, build it box it!

      Mark

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    28. Good to hear!

      Now that i think of it, i had a bad batch of J201s about a year ago..
      +m

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    29. Yep, I also had the same problem with my J201's; with the volume pot set anywhere between 10 to 1 o'clock the sound was fizzy and totally unusable. I changed few caps first, but the real cure was replacing the FETs. Now the pedal works, but the sound is still a bit harsh. Maybe I'll try setting the bias voltage up a notch, say 5Vish (4,5V now).

      Thanks for miro and Mark for all the work and spent time! Much appreciated!

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  7. BTW, great job with your layouts. Mark seemingly raised the bar fairly high over the last 300 or so, but you seem to be equal to the task. Being a total newb, and having converted two simple schematics to vero and successfully built both, I can truly appreciate what you both do, and make it look easier than I know it is.
    And Thanks Mark for the great site, effort, service and support, from across the big pond..

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    1. Thanks, for verifying and for your words. Appreciate it. A lot.
      +m

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  8. Finished this over the weekend. Sounds very much like my zendrive and Zenkudo. Just lots more gain available ( that was my main gripe about the zendrive and zenkudo - wanted more drive ). I had to bias closer to 5v. When I biased at 4.5, I couldn't turn volume down and master up - sound just went away. I thought something was wrong in my build ( might still be ), but when I biased up at almost 5v, it all seems to be as it should be. Tone controls are very interactive - sort of have to adjust one when you adjust the other ( mainly mid and treble ). Really thickens up my single coils.

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  9. Added some audio clips of this pedal on my blog. If anyone is interested:

    http://fuzzquest.blogspot.com/2012/10/tumble-and-drive-rouge-dumble.html

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  11. I have this same issue some have described with the "fizzle"....anyone ever get to the source of that or a fix?

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  12. I just built this one today. I was having a bit of an issue with the tone stack, namely the mid control. since dumbles are basically modified fender amps, I wired it's tone stack just like a fender amp. the midrange control now does what I expect to do, whereas before, at fully CW, it was more of a mid cut than a boost. mine still has a tiny area in the center of the treble pot that has a weird distortion (clippy) thing going on if the controls are set a specific way but overall, it sounds great now. BTW, 50K trimmers make it ALOT easier to set the drain voltage.

    here's my modded tone control layout:

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/Umble/01-Umble-modded.png

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  13. DONE!!!

    Pics:

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/Umble/Umble-01.jpg

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/Umble/Umble-02.jpg

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  14. I have a couple of questions. Has anyone tried this circuit at 12 volts? If so, would the bias be set around 6 volts?

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    1. I've not built this one (yet) but have built some similar, and run all my pedals @12v.....yes, approx 6v (1/2 of supply voltage) is where you want to start, but adjust from there to ear.

      HTH, Geezer

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  15. Hi guys, just wanna ask, can i put this thing in the back of the amp, i mean as a preamp that connected to return of amp? or put this thing in front of a cabsim/DI box that connected directly to mixer on stage? thanks and regards,

    desta

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  16. You can and it will sound great. Mind you that a DI and a mixer will not sound like a cabinet.

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