Meet the Fiendmaster!
(A new Tonefiend DIY Club project)

Technically speaking, original Dallas Rangemasters didn't have angel wings, though they probably should have. However, the musically illiterate treble staff IS historically accurate.

The next Tonefiend DIY Club project is a cool update of the Dallas Rangemaster treble booster — for my money, the wickedest overdrive ever. I’ll post all the project files within the next week, but I’m introducing the project here so you can listen to the pedal, decide if you’re interested, and if so, start rounding up the parts.

Like our first project, this is a single-transistor distortion device. But this one gets it glorious Brit-rock tones from a funky old germanium transistor.

At the end of this post is a parts list, plus names of dealers who sell reliable germanium transistors. And once again, Mammoth Electronics is offering a pre-assembled kit with everything needed to build a ready-for-gigging Fiendmaster. [FYI, neither I nor Seymour Duncan have any financial stake in this item. I’ve simply asked Mammoth to put together a kit for your DIY shopping convenience.] You can order the kit here. If you don’t see it on the page yet, check back — it’ll be up soon.

Check out this brief video to hear the wicked beast in action:

Funny thing about Rangemasters: Many guitar geeks have an inkling of its historic significance, but few under age 60 have actually used one. Which is weird, considering how obsessed so many guitarists are with all things retro. Probably has a lot to do with the facts that: 1) no major manufacturers want anything to do with the expensive, finicky germanium transistor that gives the device its signature color, and 2) players shy away from the term treble booster. (“I’ve got plenty of treble already, thanks!”)

If you know about Rangemasters, skip this next bit. Otherwise, just copy my lecture notes:

The pros and cons of working with fussy germanium components are so thorny that I’ve created an entire post on the topic. Suffice it to say that they impose unique headaches.

Is it worth the hassle? If you love British rock guitar circa 1970, absolutely. But if you lie awake at night worrying about signal-to-noise ratios, you may want to sit this one out.

Personally, I love Rangemasters more than my family a lot. I’ve been building these obsessively and giving them to friends, who are inevitably floored by how great this little circuit sounds. So edgy, so stinky, so rawk.

Experienced DIY builders, bear with me — I know I sound like an über-n00b, rattling on about this simplest of circuits. But trust me: I’ve witnessed a number of guitarists and producers — people whose music you know — flip out when they plug into one of these for the first time.

Will you share their enthusiasm? Build one and find out!

Download the part list here.

If you need to purchase a germanium transistor, but don’t want the complete Mammoth Electronics kit, here are some good sources. (If you’re not sure which type of transistor to buy, please read the Germanium Mystique post. Or just get an AC-128, a relatively common model that happens to sound awesome in this circuit.)

72 comments to Meet the Fiendmaster!
(A new Tonefiend DIY Club project)

  • Keith Parks

    Thanks.  This is going to be great.  I got my bread board ready.

  • Tim Dinkins

    I built one of these just to see why people thought they were so great.  I too was blown away by the sound of this pedal.  So much so that I built a second one with switchable capacitors to make it more versatile.

    When I built the first one, I used some Radio Shack ceramic caps that I had on hand.  When I build the second one, I used higher end poly film caps.  Weird thing was, the first one sounded better.  So, I swapped the transistors (re-biasing as well) and the first one still sounded better.  Then I swapped the cap for a ceramic, and the magic was back.  I think that low-fi ceramic caps really add to the sound of this pedal.

    Also, I have a 57 tweed champ clone, and when using a neck humbucker with the amp cranked, it can get pretty muddy.  Adding the range master really cleans it up a makes for a really nice tone.

    • joe

      Wow, Tim — thanks for the post. I’m having major déjà-vu, because I could have written the exact same observations a couple of years ago. I was convinced that funky ceramic caps sounded cooler than high-end ones.

      But then one day, I built a few stompboxes and made comparative recordings using a ReAmp. I listened carefully and took measurements. And I had to conclude that all the differences existed in my imagination. Bummer — I really wanted the cheap caps to kick ass on the expensive ones, ’cause it makes a better story! 🙂

      I posted the results to, my fave DIY site. Here’s a link:

      Joe Gore’s Cap Test.pdf

      You can read the long, um, passionate discussion on the site if you search for “Joe Gore’s Reasonably Scientific Capacitor Test.” (I believe you must join for forum to access the thread, but that’s cool — it’s free, and FSO is a great resource/hang for DIYers.) 

      The test wasn’t comprehensive — just two circuits and two cap types (Topmay polyfilm box, and Radio Shack-grade ceramics). Perhaps some people can hear a slight difference, but I certainly can’t. If you can make some comparative recordings, please post them, because I would LOVE to be proven wrong! But for now, I have to conclude that, in stompbox circuits, the cap material makes little or no difference. (Obviously, the differences between cap values can be extremely dramatic.)

  • I’m joining the club with this project. Mammoth just shipped my kit. 

    I’ve breadboarded a few projects and done various repairs/maintenance projects, but this will be the first one that I’ll get boxed up and ready to go for daily use. I have been really enamored with an old Gibson Skylark amp (Crestline) that I bought 10 years ago, sold to a friend, and recently bought back and restored. It will be fun to try to tailor the Fiendmaster to this amp.

  • El reclusa

    I wonder how different a crestline Skylark is from the tweed one I have. I love that amp, but rarely use any distortion devices with it, since it’s so easy to just turn it up for glorious, raggedy-ass overdrive.

    Man, I gotta get on the ball with these projects! As soon as I wrap up the Esquire I’m building…

    • The only other one I’ve seen was the same model. It’s really crying out for a tremolo (and there was a tremolo model) so that will be one of my future projects. So far I haven’t gotten any overdrive pedal to sound good with this amp, but I love it for its clean sounds nonetheless.

    • joe

      You guys really should try the Rangemaster with those great, small amps that already seem to have a perfect distortion sound. It’s not “distortion” in the sense of slathering a bunch of ugly filtering over everything. It just sort of “nudges” the amp, giving you distorted sounds that keep a sharp edge, as opposed to farting out. Trust me on this one. :satansmoking:

  • Is the power supply jack compatible with a typical Boss 9V power supply?

      • Cool. Good to know… I have a few in my closet, leftover from before I stopped playing electric guitar for 8 years.

        Well, I have mine on the breadboard and working (I’m glad I found the cheap shipping option because it turns out that Mammoth is only about 100 miles away), but I can’t give it a fair try until tomorrow. 

        I found that the pinout of the AC128 didn’t match your picture. I’ve checked it about a dozen times; mine matched this photo (which is clearer than yours): 

        Could I have done something else wrong that would make the transistor behave backwards? I hate to think that I’m missing out because I stumbled on something that works, but not right. I’ll recheck the whole thing in the morning just to be sure. 

        I’ll make a quick recording tomorrow and post it to see what you think.

  • Here’s a brief clip with the bassier input cap and the Fiendmaster’s volume low enough that the amp isn’t overdriving. Is that the sound you’d expect from it? (Cheapo Epi Les Paul, DiMarzio distortion pickup wired in parallel, Skylark, SM58)

    I can definitely get some very cool and useful tones out of it as it is, but I wanted to make sure I didn’t do something wrong before I make it permanent. 🙂

    • joe

      Yeah, that sounds about right! There’s one thing though, that I debated whether to mention as part of the project, and perhaps I should have, so I’ll do so here:


      In fact, when I make them for myself and others, I usually omit the volume control. With this circuit, the magic is all about whacking the amp HARD with the filtered input. It’s not like, say, playing a Tube Screamer, where the you get a fairly consistent timbre across a wide range of output levels. It’s more about setting the effect and amp to “burn,” and emerging with “burn squared.” In other words, unlike most modern overdrives, the amp pretty much has to be overdriven for best effect.

      So why include the volume knob in the project at all? I guess because users expect it, and for some, it’s just unworkable to have an overdrive that kicks in such a huge boost relative to the bypassed signal. But I’m more likely to just leave it on and control the level and distortion from the guitar’s volume pot, a technique hinted at in the demo video.
      How about some more clips with the pedal and amp floored? Post ’em quick before the SWAT team arrives.  :satansmoking:

      (You can just say, “But officers, I’m a classical guitarist!”)

  • I don’t see the point of the volume knob, either. But I’ve got the kit and that hole’s drilled in it, so I may as well use it unless you can think of another use for that pot in this project.

    I did record myself trying to improvise stuff suited for this thing, but I don’t think the world needs to hear me play make believe. I need to live with it for a while first.

    I like this device better with my Vox AC4TV than my Skylark. My Skylark is really harsh when overdriven, and has a ton of clean headroom, so by the time it overdrives, the tubes are rattling in their sockets, my ears are ringing, and the swat team has already opened fire.

  • Mike

    ordered my kit yesterday. don’t know what to expect with my crappy entry level equipment but this is more of an experiment to get me into tone experimentation and seeing what I can coax out of my practice amp. which I will probably mod the shit out of soon, cuz I like to break stuff.

  • Rich


    Do not see the layout or the schematic for the Treble Booster.  Received the kit of parts today.

    Tried the link to the BOM, but it does not work.

    Will be fun building the RMTB in a foot pedal chassis!    🙂  

  • Travis Artz

    Hey, this is my first DIY project! Just got my Mammoth kit in the mail and I am very excited to get started.

    Had two questions. I jumped right into building this Rangemaster clone, but I noticed that one of the earlier projects focused on a Fuzz pedal. I was looking to purchase a good fuzz pedal along with a good Rangemaster clone a while ago until I ran across this site. Would it be worth it to buy the parts to assemble the fuzz or do you think I can achieve most of it’s sounds with the “Fiendmaster” (considering they both use Germanium transistors)?

    Also, I was thinking about doing some designs on the pedal, adding color and whatnot. Are you familiar with what kind of paint works best with these enclosures?

    Thanks for the help!

    • Travis Artz


      Don’t know why I assumed the fuzz pedal DIY project also worked with Germanium. My revised question would be this…

      I am looking for a fuzz that has qualities of a 60’s/70’s kind of Germanium fuzz. If I am building the “Fiendmaster,” can I get those kinds of sounds out of it or do I need to look elsewhere for that particular fuzz distortion?

      Thanks and sorry for the confusing

        • joe

          Well, the Fiendmaster is real close to a Rangemaster, more of an overdrive than a fuzz. (It was originally called a treble booster, but I believe overdrive is a better description.) The two best known germanium fuzzes were the original Fuzz Face and Tone Benders. They’re really ’60s effects — by the ’70s, silicon had pretty much replaced germanium. In other words, the Fiendmaster, awesome as it is, is probably not exactly the sound you mean.

          We’ll probably to a Fuzz Face project in DIY club. In the meantime, I heartily recommend the Build Your Own Clone Fuzz Face and Tone Bender kits if you want to get started now.

          • Travis Artz

            Thanks for the help! Gonna go ahead and build that fuzz!

            Any advice on what kind of paint to use to make designs on the enclosures? 

  • hi —great blog
    just breadboarded my first project the fiendmaster —sounds amazing,
    couple of questions – I can’t seem to get the pot to change the tone between the input caps – was this a feature on the original peddle?
    + excuse my ignorance but I had always heard that distortion/fuzz was a result of diode and transistor clipping – but you don’t mention any diodes in the breadboard part of the circuit? is it possible to add a diode for different tones also?

  • just realised that read a little wrong
    what i meant to say was it a feature of the original peddle to be a ble to change tone –or was it simply turn on and increase or decrease volume?

    • joe

      Hey Steve — glad you dig it!

      No — the originals did NOT have an adjustable tone-changing input cap, though several noted players experimented with different values as part of their signature sounds. You can simply try different caps and use your favorite value, omitting the tone control knob.

      Are you working from the current version of the project file? An earlier version had a typo which may have messed with the performance of the tone pot.

  • I see —maybe that’s why it didn’t work —
    is their an updated pdf explanation of how to fit the tone pot – as I’m not up to speed dealing directly with schematics (yet)
    also — so the rangemaster didn’t use clipping diodes either?

    • joe

      The PDF linked to above is the current one. The version number is on the front page of the PDF.

      No, Rangemasters don’t have clipping diodes, nor do Fuzz Faces or Tone Benders. Which is why they sound so good. 😉

  • thanks for the extra info Joe
    I look forward to future projects

  • Hi Joe
    any tips on shielding the fiendmaster project? I’ve only breadboarded it so far and sometimes it’s a bit hissy and spluttery – and sometimes it’s not? would this be a shield issue or do I have leaky tranistors?
    same thing happens with both my ac128s

    • joe

      hmm — it really shouldn’t need shielding. It’s innately a rather noisy effect, but it shouldn’t be louder than what you hear in the demo video. It’ll definitely hiss a bit when it’s cranked, though. I suspect it’s not a problem with the transistors. Also, it’s shouldn’t vary much. I think it’s way likelier the sputtering is a loose or shorting wire in your breadboard layout.

      Try powering it from an AC adapter if you’ve been using a battery, and vice-versa. Also, try building the layout on breadboard from scratch again using different holes. (Actually, a helpful mental exercise in any case.)

      The enclosure itself should offer a fair amount of shielding.

  • Derick

    I understand the reasoning behind running at full blast. I do. But I would still like to have the gain/volume combo. Or at least try it in breadboard. How exactly would that work?

  • joe

    Run the output of the circuit to lug 3 of on A100K pot. Connect lug 1 to ground. Lug 2 is the new output.

    But you’ll see — you’ll keep turning the master volume all the way up. 🙂

  • Hector

    Okay.  Found it.  I had been looking under fiendmeister!

  • Hi there!

    I’m really excited about building my very first pedal, and was looking into the Mammoth kit, but the webpage states it includes “everything needed to transplant the circuit into a box”… Does that mean that I should get the components elsewhere? 

    I know, kind of a noob question. Sorry/ thanks a ton!!

    BTW: You, sir, are to blame for my butchering my tele to try the broadcaster wiring… And turning it into a tone monster!!! Thanks again!

  • blake

    bought the kit from mammoth, finally got around to giving it a stab today. I’ve built a few kit pedals on PCB and struggled mightily doing a DIY fuzz previously. Slapped this together and……just  nothing as expected when plugged in. Reading schematics is like reading latin for me still for the most part. Anyone have a pic of a completed one of these from the wiring side so i can play “make mine look like yours”?

    • joe

      Sorry it didn’t work the first time Blake. My best advice remains what I said in the intro to the project: Even if you don’t build the first two projects, at least read them through, because they explain all the schematic stuff. They really aren’t as tricky to understand as you’d expect.

  • blake

    ah see, I skipped right past the intro project. 😉
    I’ll go study up and pull out the old multimeter this week. I’d still love to see a shot of how you attached everything to the middle of the socket tho

  • Eric T. Lurick

    A veroboard layout would also be great to get this project looking nice and tidy. Maybe someone here has already made it?

  • Hey Joe,

    I’m also having a lot of trouble with noise issues – to the point where I can’t even really tell what the circuit sounds like on my breadboard. It sounds like sh*t, to be honest, because of all the noise. I breadboarded the first three Tonefiend projects and had them work without issue, so maybe I just live in a noisy place and the germanium transistors are more sensitive, or something.

    Anyway, I’m going to go ahead and box it up in hopes that the final product will get rid of the noise issues. I’ve built several other boxes and some had similar noise issues.


    • joe

      Sorry about the noise, Gerald. Those transistors are noisy for sure — but it shouldn’t be so bad you can’t differentiate the signal from the noise! Maybe try another transistors? And triple-check all the ground connections?

      • As I suspected / expected, once I boxed the circuit up, all the issues disappeared. I think I just have too much RF noise around – often when adjusting pots a local radio station will come blasting out of the amp. With a wireless router, two computers and at least 3 wireless devices powered up in my house at any given time, I can understand how that might be a problem. But now that the circuit is boxed up, it sounds terrific!

        So I guess this raises another question – do you do anything to shield your breadboard while working? I could build a cage for it, I suppose 🙂

        I love your blog, and this DIY effects series especially. I built a few BYOC kits before trying the first three, but I really feel like I understand what I’m doing after building the Tonefiend projects. Do you have plans to do any more effect boxes?

        Here’s a pics of my build, just for fun. Thanks again!

  • Greg Woods

    Just finished boxing up my Fiendmaster. Although it sounds glorious, there is a spitting, sputtering noise emanating from the pedal that becomes more evident as I turn the volume down on the guitar. It was there on the breadboard as well. When I breadboarded it I initially installed the AC128 using your pinout and it didn’t work, then I found William’s pinout reference and used that. Voila! So my question is could I have damaged the transistor when I had it installed incorrectly? Would that cause the sputtering? Not seeking to lay blame, just looking for answers. Thanks again for such an awesome website! You’ve helped me with so many projects and ideas already, looking forward to more.

  • joe

    Hi Greg! I’m glad you liked the project. Chances are you will not have harmed the transistor. Often sputtering happens when the transistor doesn’t have enough juice, so I’d start by double-checking the value of all the components, especially the resistors. The sputtering often happens when the transistor isn’t get enough juice, so pay special attention to the resistor connecting the transistor collector to +9v. Also, it might be worth “reflowing” some of the solder connections, in case any are intermittent. Just touch the hot iron to each jont for a sec till the solder gets runny.

    Let us know if this helps! 🙂

  • Greg Woods

    I’ve been out of pocket for a bit, finally got a chance to try the Fiendmaster again, now it’s as quiet as a church mouse! On batteries and on my pedalboard that is. Just took it off my pedalboard and tried it solo and the sputtering is back, but only when the guitar volume is rolled off, it goes away as soon as I turn up. Just like before. All of my other pedals are off as well as true bypass, so no buffers are influencing things.

    I’ve found another issue too. When I plug in my OneSpot adapter I get a loud shhhh sound that diminishes as I turn the guitar up, but then the sputtering comes back at about half volume.

    Oh well, I’ve got a few other pedals that work/sound a lot better on batteries too.

    Not sure that I wanna mess with trying to desolder and replace things just yet. But when I do, would increasing C5 help with the shhhh? And just to verify, is R3 the resistor to change? What value should I try? 3.3K?

  • Greg Woods

    On the plus side. While the Fiendmaster of course sounds incredible pushing my little Valve Jr. into glorious overdrive. It takes on a completely different character running it into my Crate G130C solid state 212 amp. It becomes a great clean boost! Very sparkly and incredibly dynamic!

    And when I run the FM in to my DOD 250, the FM pushes the 250 over the top! I can use the 250’s gain knob to go from mild distortion to full on fuzz, all while controlling the overall volume with the 250’s level knob. What I love so much about this setup is how I can clean things up using the guitar volume. So much flexibility with just two pedals!

  • Craig

    Hi, I’m having problems with this pedal. I’m near positive that I have assembled it correctly but when I try to play, only the very aggressive strums get through and they die pretty quickly (Almost like the reverse of a compressor). I’ve double checked all resistors and caps for being the right value.

    This is my first time making a pedal so I could just be making a real newbie mistake.


    • joe

      Hi Craig — it sure sounds like an issue with one of the resistors connected to the transistor. If you have a multimeter, check for component value and use the continuity function (the beeper) to verify the connection. Less likely, but possible, is a bad transistor. Any chance you can get your hand on a couple more and try popping them into the circuit to see whether you encounter the same behavior?

  • hi Joe,
    Fiendmaster is one of the most flexible Boosters i have ever tried.
    i did a vero-board layout of the circuit (i hope you don;t mind) here:
    and also added a Sziklai pair option switch for boosting with a fuzz attitude. (daughter board),
    or all-in-one- vero board:
    thank you for this wonderful project.

  • Josh

    Could i use a 330 K ohm in the NPN circuit instead of the 470 K resistor

    • joe

      It will change the amount of voltage reaching the transistor’s base. I have a hunch it will work, but I can’t say with certainty. But hey, the part in question only costs a few pennies.

  • Novice

    Thanks for this and the other projects. This is a great way for a novice to get started. With that said, I’ve found a couple of funky things with the instructions for the Fiendmaster. First, on page 12, you say to connect the transistor collector to the positive bus with a 3.9k resistor. Yet the schematic on page 8 shows the transistors emitter connected to the positive bus with a 3.9k resistor.

    On page 28, you give two conflicting instructions for C3. Presumably you mean one of the caps mentioned to be other than C3; could you clarify?

    Finally, I noticed that the boxing instructions for Project 1 involve some stuff that doesn’t seem applicable to this project, such as connecting a wire to an unfilled pot lug (all the pot lugs have something soldered to them in this project). Again, it would be great if you could clarify what the differences are in boxing Project 1 v. this project.

    Thanks again for these great articles!

  • Erik

    Hi Joe,
    First, thanks for your post on David Bowie. Of all of the articles and remebrances I read that week, yours was the most meaningful to me.

    Anyway, I boxed up my Fiendmaster, and it sounds fantastic with a 5-foot cable between the guitar and input. With longer cables it sounds like those mentioned above where it’s choked and has less sustain, like the transistor is not getting enough power. The cables have the same reistance for the input point 0.7. The resistance on the “good” cable’s ground is higher (1.4) than the other “bad” cables 0.5). It’s odd. Do you have any suggestions on things to check or try? I’m not done with fuzzs yet, so I’ll be plugging in other Ge transistors in as I aquire them. Fun projects; they keep me playing.

    • joe

      Hi Erik! Wow, changing the cable should have no impact beyond the minor impact you’d expect from longer/shorter and brighter/darker-sounding cables. I use the circuit with 20′ cables all the time. My admittedly tiresome suggestion is to check the board, verifying connections with a multimeter and (especially) triple-checking the component value of any parts that connect to the transistor, especially those resistors. Let me know how it goes!

  • Will

    I would love to build the Fiendmaster but it seems that the much needed project files (including the all important schematic) posts are not available. At least the links are no longer functional. I’ve built several Rangemasters and I love that circuit. Like you said, it RAWKS. Nothin else like it. Does the kit from Mammoth include the schematic?

  • Will

    OK. Sorry, I’m a dweeb! Found them, the Fiendmaster project files that is, including the schematic. My apologies for the errant post.

  • Skot Jakubiec

    Hi Joe- I have this breadboarded and I think I like how it sounds, but I have one question: should the gain work almost like a volume? When it gets to “0” the sound is totally cut off.

    • Joe Gore

      It sounds like you have the gain pot connected to ground. It shouldn’t be. UNLESS you like having work that way, which you might. 🙂

  • Skot Jakubiec

    Why yes, as a matter of fact I do- Thanks man! I love it when there is a reason for something to be not working!

  • Skot Jakubiec

    Sorry to bother you again Joe- how should it be wired? On page 14 it says lug 3 to the emitter, 1 to ground, and 2 to an empty bus.

  • Greg

    I just got finished my Fiendmaster, and I was blown away. What an amazing pedal! I’ve been reading some of the comments about the sillyness of having a volume knob, but I respectfully disagree. My Fiendmaster is too loud with the volume dimed. I had to roll it back to about 2:00 so as not to piss-off my bandmates!

    Absolutely love the effect. It sounds bitchin’ with into my Ceriatone Son of Yeti (Marshall Plexi) using single coils or humbuckers.

    Skot: I also got confused wiring it up. You’ll need to refer to Project 1 – Part 4 for boxing instructions, but don’t follow them exactly. They diverge a bit. I found the photos near the end of the Fiendmaster file very helpful. They show clearly where the input and output wired need to go. I think I had 4 wires grounded to the middle lug on the stereo input jack.

  • Greg

    Here’s a pic of my build, hopefully it will help.

  • Skot

    Out of frustration I lost enthusiasm for the project a while ago, but I intend on retrying it soon.

  • Brandt

    Way up there somewhere there was a mention of no volume control on the pedal. This is my absolute favorite build, I’ve made 5ish and breadboarded with it for hours.

    I find a volume control is a HUGE advantage over a gain control. (I dial in the gain and go with a set resistor and typically don’t use a tone pot).

    I park the pedal volume at unity gain (pedal off volume = pedal on volume) and there is a fantastic break up/overdrive/pick-your-term. AND I can bring it down to a cleanish boost with my guitar volume AND AND I can always crank the pedal volume if I need to crack windows, or exfoliate my brain.

    Thanks for all the great builds, Joe!

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