Tag Archives: noise

Tone Bender Mki builds rehash and musing

As of today, if you google up stuff like:

Mki tonebender transistors hfe and leakage

There’s just no way to get all the info on one page. People in the know are keeping their mouth shut as to what the best leakage and hfe combinations should be, to get an up an running mki.

I’d just save Electric Warrior from the bunch, an extremely knowledgeable guy who is not afraid of sharing his views. He’s active on fsb and on the dam forum.

Now this pedal.. There’s no easy way to pull it off. 

You think you’ll go the easy route and buy a tested, measured set of mki trannies online? Ok, no. Dont do it. The build will sound shit. They dont even come close to the ideal values-heres my experience with tested transistor kits:

Measured set 1: “compatible subs”

Q1: 2N404 (how original) hfe 81 lkge 0.04 (yeah, right)

Q2: 2N404 hfe 136 lkge 0.12

Q3: 2N404 hfe 93 lkge 0.00

I even spent more money on a set of mki matched OC75s, I made a couple of clones some time ago, just to review them again the other day to find the bitter truth: no sustain on notes up the fretboard. Fail.

Ok so i broke one of the clones open, socketed all the transistor points with alligator clips and i plunged into my collection of germaniums.

This idea on my mind:

John Barry’s guitar player asked Gary Hurst to increase the sustain of his Maestro FZ1 pedal. He changed the transistors, power supply and resistor values to go with the mods, and the first (Mark One as we call it today) Tone Bender was born. 

How is it supposed to sound?

-the Maestro FZ1’s tone is “brassy”, and it can be also very velcro like, turning the guitar into a ratty device (the green acres tune) so it’s got a varied range of sounds on tap

-the Maestro FZ1a sports less dynamic range as units were mass produced, so bias can often be unfocussed, lets say it’s buzzy but also voiced very differently from the FZ1

-(not on topic but since it was used a lot back in the 60es i’m gonna throw this in too) the (germanium) Mosrite Fuzzrite has a “synth”-like sound, the guitar’s articulation and dynamics are greatly reduced, almost squashed.

We have very little evidence of original, still working mki pedals, and we are all accustomed to the youtube links to listen to those. Pedals age, and they do not sound as they used to, when they were new.

But keep it in mind: like a Maestro FZ1 with more sustain.

Put these people, the players, on the map. British freakbeat as we now call it-before it was just called r&b. Ok most of them used british pedals. Tone Benders. Some just diyed the Maestro, or whatever they could copy, even guys like Syd Barrett (early Pink Floyd) would tinker with building their own pedals.. These “minor” bands never toured the States, the money they had, went on clothes, and maybe a better rig, for sure not on a US made pedal-ok maybe some of them had bought a Maestro in the wake of Satisfaction. They made the european summer circuit, scaring the continent’s patrons shitless with their fuzzy sound-lol.

Also, they sound way more obnoxious than american garage bands, save maybe the texans-the cowboys i assume, switched to the more aggressive, silicon fuzzes earlier than anybody else, because of the temperature boiling their fuzzes at gigs.

American bands were looking up to Great Britain up to a certain point. But not the other way round unless you were a top player that visited the other side of the pond enough to be influenced by the vibe-or until the summer of love, but thats 2 long years later than what we’re on about here.

Americans were into the Yard-Birds big time.. The Litter sported the open tones of oc75 induced harmonics of the Tone Bender on their signature regional classic Action Woman-complete with Yardbirds style rave on (that the Yard Birds in turned had copied from people like Lonnie Mack’s) and thats 1968, a few months shy from the Zeppelin’s telecaster-and-possibly-a-Bender-into-a-modded-HiWatt debut.

Back to 1965 now.. Would you like to  listen to some Mki? Get the British Freakbeat compilations and dig.. there may be some.

Tone Bender Mki: high treble content, dark british amps, loud and with lots of sustain to cut through the mix. Think Baby I Go For You by the Blue Rondos, or Ronno. Like an half cocked wah. No velcro like the Maestro, but still based on the Maestro. Resistors to open up the sound.

I’m delving into the idea of the possible Maestro modification: putting an OC75 on q1 as a driver, and leaving 2N270 on q2, q3, on a mki build. After all, the original q2 and q3 in the mki are two 2G381, a random torrid germanium transistor never to be heard of again. Same as the 2N270.. probably the cheapest parts they could find.

Im going back to my Maestro builds, and an old geofex article.

-q1 must leak to activate q2, q3 leakage means sustain. If i remember correctly..

Here is my build:

Q1: oc75 hfe 78, lkge .32

Q2: 2N270 hfe 108, lkge .21

Q3: 2N270 hfe 401 (!!?!)*, lkge .66

*now a value like that should give you an idea of how shitty a transistor that is.

Don’t hunt for 2N270s. It’s not worth it. You’ll end up with a hole in your pocket and no satisfaction. Their specs are all over the place. And they dont sound like they measure. I went through a large batch of Fairchild 2N270, at an excellent price, and sorting them out has been hell. Thank God i have only about 20 RCAs, i keep them locked, they look nice and fat in their new old stock boxes and i will never use those. But they are the same. No quality control, folks. Or rather.. those were the times.

You can achieve the same results using other leaky transistors. Dont worry about the tone, the layout provides the tone on this one.

Dont change the layout values: leave the 470k resistor there. 

Keep q1 hfe at round 70-80, leaky, q2 hfe in the 90-120 region, with leakage, and q3 not over 100 but it should leak loads.

😉 good luck.

Yocto 808 building tips

Some tips and notes on how i built my TR808 clone, the marvellous Yocto 808 project!

Buy the kit and subscribe to the forum here: http://www.e-licktronic.com/en/content/25-yocto-tr808-clone-tr-808

yocto hlf kit received

I do not think it is a difficult nor long build – i spent a couple of hours at every day off on it, for about a month.
The excitement of being able to own an 808 drove me, and gave me the needed focus and patience boost.

yocto genesis (09)

When building the Yocto, it is very important to measure every component before soldering it.
I decided to buy the resistors needed each time I was going to start a new section. This relieved me from measuring hundreds of resistors in one tiring session, put them in order all at once, etc.
I bought a paper note book on which I would tape, writing down their value and position the components, as I prepared them for each part. This helped me double check them before and while soldering them to the boards.

yocto tips notebook

I decided to socket all the IC’s and the noise section transistor.
The germanium diodes provided in the half kit are rare, treat them with care. I cut the curvy terminals to have a straight lead as per picture here.

yocto diodes
Check the pictures I enclose here to clarify certain ic’s position.
I made the mistake of putting all the pots at the end, do not do it, it is a mess. Just follow the build guide-do it as recommended, at the end of each section.

Remove the encoders’ tabs before you solder them in! 


cut this part of the two encoders and the tempo pot
Please note that you do not have to cut the lead cables at the end of the build (i did it!), what Vincent meant in the last paragraph of the build guide is, you can make them shorter.
I had some issues with the flat cables, aka they broke, so i socketed them too. It is advisable to have a suitable enclosure ready before you get to link the two pcbs with flat cable, otherwise having the boards moving around will cause them to break.

yocto genesis (32)
Usually the boards sit a bit shallow in the enclosures, do not use led covers and cut them about the height of the sequencer’s coloured buttons.
Use 5mm spacers to lift the board up and have it sit properly, the keys will stick out properly through the holes.. More on that further down..

(see pic at the top of the post)

A few more tips to build the yocto, not a mod guide by any means, more like a ‘watch out for’ list, for instance where to look if you would like to change the value of some resistors to change the tuning of the instruments.. and other useful things to know as you go along.

A lot of these ideas are to be found in the yocto forum, but here is whatever I found essential to complete the build without headaches.

For a more in depth mods’ list, google dsl-man yocto mods.

As opposed to the building guide, a more effective functionality of the noise generator can be achieved with this mod, as per the official Roland service manual (page 15):
R 129 use a jumper instead of the resistor listed
R 131 100k
R 127 10uF electrolytic: see this pic for correct orientation (positive side left)

R 130 22pF in parallel with resistor 130 (it means on top of the resistor, using the same soldering points – check the pic, i soldered it on the other side of the board)

I socketed Q35 as it is a very substantial part of the noise generator.

yocto noise section mod betternoise section yocto 808 mod

C 27 1n2 for 1ms pulse, needed for an effective accent

R 165 tuning resistor

R 234 47k (positioned in the Low Tom section)
R 188 check its position carefully
R 195 tuning resistor 1
R 196 tuning resistor 2
R 202 noise filter resistor

yocto toms

yocto genesis (14)

R 231 to lower pitch, use a 4k7 resistor (or increase value to lower pitch)

R 257 tuning resistor

R 284 tuning resistor

yocto genesis (16)

R 312 tuning resistor
R 315 tuning resistor
R 334 and
R 373 are part of the Hand Clap circuit, although they are to be found here

R 342 and
C 137 may have a solder bridge, it is ok
Do not rush to solder the BA6110 ic, it is better to socket it and add it at a later time, please check the picture here to have it positioned correctly.

yocto genesis (29)

R 63 decay resistor 1
R 65 decay resistor 2

Look at this section before trying to find the position of the components. It is L shaped.
R 56 noise filter resistor 1
R 58 noise filter resistor 2 (this is in common with the HiHat)
C 6 and
C 42 and
C 44 and
C 46 I did not have any 22nF caps in my stash so I used, 27nF instead.


Please note the position of this IC

yocto genesis (30)

yocto genesis (22)

Before you put the keys in, make sure your enclosure will let them stick out properly (as stated before, they sit a bit shallow), and use spacers the right height to suit your eclosure.. As described here..

Before you put it in the enclosure

Prep the enclosure by screwing the spacers in the front panel- i used 5mm spacers but 10mm spacers’ screws (aka the ones that came with the mouser order) that go in for like 3/4 of the spacer’s lenght. Screw the top panel side all the way in through the spacer. 

Please note there are two sides to the spacer, one is hollow and the other flat. You want to have the hollow part as receptacle to screw the pcb side in (aka at the back of the front panel) as much as you can (it is not much, a few mm’s but that will suffice to have the pcb steady in place). This means, flat side of the spacer on top.

Look at the picture:


top panel screw: screw the spacers in flat side up, hollow side down
Nuts of the two encoders will have to be placed on top of the front panel not below.

My Yocto fired properly first off.
I made all the trimmer’s adjustment upon finishing it.
I am very satisfied by the result. Vincent has been very helpful too, and the YOCTO forum is an invaluable resource.

yocto genesis (26)

Thanks Pawluk for the sturdy enclosure!

2016 02 222

Also, if you feel inclined, i would suggest you add a little daughterboard to fine tune the noise generator, to allow for correct voicing of the snare, hats and cymbal (check out the relevant resistors above and swap them with trimmers)..

I arranged them on a small veroboard and i am very happy with the results!