Tym Dead Mud

With the shop (mostly) closed due to COVID-19 I've been going through boxes at the workshop looking for things I can build while some of my supply lines are down. I've made some special one-offs and some pedals using a box of front plates I found that Tony and I had worked on and never used for various reasons.

A few years ago when I was looking around for info on the ELK Sustainar I stumbled across another Japanese Big Muff variant I hadn't thought about for years. I remember seeing these when the internet opened up my world to exciting new effects but I've never actually stumbled across one so it had disappeared from my puny brain.

The Rozz DH-01 Dead Heat fuzz, like the ELK and the Acetone FM3 were all Japanese made fuzzes based on the Big Muff idea although Rozz started making these in the late 70's based on the original early/mid 70's circuit. Other countries and brands jumped on the BM circuit early because, well, it's a great circuit. Jordan, Hohner, Colorsound and JEN were all making Big Muff inspired effects by '73/74 and other Japanese manufacturers like Maxon were using the idea by then too. 

Info on Rozz and these Dead Heats is hard to find but they were made in Japan by Katayama Electronic Musical Instruments (Milan) and Rozz did make at least one other pedal called the SUPER GAS, which was a Flanger in the same enclosure. The main difference between the Dead Heat and all other BM inspired fuzzes was, this version uses 18V to run the circuit for more headroom and volume. 

Now, all of my Big Muds are based on pedals I have actually had access to or I've been sent really good pics and info from the owner and sent them one to test against theirs for confirmation. As I've never had access to an actual Rozz Dead Heat I couldn't really make a clone with any certainty. I do have a hand drawn schematic and pics of the PCB (there is a newer tagboard circuit available but I haven't tried it) sent to me by a Japanese friend many years ago but I haven't actually heard one so .... I made an 18V Violet Rams Head (similar to the Dead Heat) to see what it sounded like.

There's a few places that claim these originals had a "charge pump" for taking the 9V up to 18V to run the circuit but all the pictures I have of the inside of this pedal show only the fuzz circuit and the fact that it takes 2 9V batteries with NO power input jack it appears to be a straight 18V circuit, unless different versions were made of course. The modern tagboard incorporates the pump to plug a 9V straight in.

The original was built on a typically Japanese looking etched PCB using common metal film resistors and green caps where standard electros weren't used. The circuit has 4 2SC1000 transistors and silicon clipping diodes. Everything looks really nicely made with good quality components.

My 18V versions sounded good, with HEAPS of volume and really clear headroom but, up to the point of a standard (or a little higher) BM volume it sounded like any other BM with this circuit, and, it got way too loud to use past this so while it's a cool idea, I just couldn't run it that hard, even with the volume down which affects the tone/bottom end in this BM circuit. So, I figured IF I couldn't hear a real one and IF I wasn't sure mine was similar and IF I thought it was not much different from my standard BM, I figured I'd make something that "simulated" the idea of a REALLY loud BM with heaps of headroom and clarity that ran off a standard 9V power supply.

This is my Tym Dead Mud using a modified Op Amp BM circuit with an extra transistor gain stage at the end and NO diode clipping with no mid scoop and a bass boost at about 200Hz from the mid point on the tone control up. This circuit is LOUD. I mean it's by far the loudest Mud I make and with the component choices and no diodes to clip/compress it's great on guitar and bass with plenty of bottom end.

With the gain down low it's pretty dark but unity volume is at about 1 on the volume control so there's plenty to play with. It brightens up and really starts to cut at about mid gain and then cuts loose on higher gain settings. With the gain on full it starts to compress and splutter a little bit as the circuit is so saturated but still reasonably quiet for a distortion circuit with this much gain.

The tone section is a different sweep to a standard BM and having no mid scoop makes it sound much "fuller" throughout which beefs up a little with that bass boost in the treble areas. With the volume and gain on full it's seriously stupidly loud, but, well that can be fun right?

The original had an LED that was on all the time like the old Guyatone pedals to show there was power to the pedal and had a switchable volume pot to save battery life (although the bottom plate still informed you to "For longest battery life always remove instrument cable from jack when not in use" so as nod to the original I have the "OFF" at the volume knob which indicates the circuit is off, so just to confuse you all the LED is on all the time and goes off when you switch the fuzz on. 

Tone probably forgot about these artwork plates (I did) so I'm going to use them up on this circuit and see if people like 'em. I have 10 plates here so if I send them out and people like them I'll get more printed. If people tell me I'm silly for making a fuzz so loud I'll leave 10 of them out there in the world. At least the plates are getting used.

I should have the first 5 ready in the next couple of weeks all going well.

May 19 2020 Written By: Tim Brennan