Wednesday, 20 February 2013

Fulltone 70

Info about the original:

Ever played an original FuzzFace from around 1970? (HINT: Not AT ALL the same sound as ones with the same namesake being mass-produced currently.) Ours has two intentionally mismatched (for harmonic content) silicon transistors that snarl and spit... not for the meek! If you put the "Fuzz" on 10 you will rip, and you might get all sorts of oscillation and weirdness... but that's Rock. Don't try using it with a wah wah... you can't, and neither could Jimi, without it screaming and howling. You want polite and quiet? Go elsewhere. You want art in a box? Come on in.

Housed in a 16 gauge steel box and powder coated deep blue, this pedal is a bit unruly but with some warmth... ideal for older 4 input Marshall amps, it has much more FUZZ than the '69 Pedal and includes a Mid control for extra clarity and cut.

I got my hands on Eric Johnson's Blue Fuzzface that he used from Tones through Ah Via Musicom period (now owned by Ian Moore) and incorporated a few of its tonal secrets into the '70 pedal with staggering sonic results!

Product Updates:
In December 2009, after 15 years of production, the 70 was discontinued. However, I recently found/bought a couple thouusand excellent BC108C transistors, so am happy to announce the return of the 70 pedal... this time, in a small (OCD-sized) housing. These transistors sound outrageous! This model 70-BC still has the secret-weapon "Mid" knob which will allow you to do something other Fuzzfaces won't let you do.... be heard in the mix. ;)







65 comments:

  1. Replies
    1. Most medium gain silicon NPN transistors should do. I'm probably going to build this with a 2SC1815 and a BC550B.

      Delete
    2. Thank you! Any diode replacement? I've got a bunch of 1N4148 and 1n4007

      Delete
    3. The 1N4148 is exactly the same as the 1N914 so no worries there, as a replacement for the germanium diode I'm not sure. It will certainly work but I would expect the response to be somewhat different. Basically give it a try with the 1N4148 and see what you think.

      Delete
  2. Curses. I laid the components out on my desk, warmed the iron up.. I'm all out of vero. I'll be tackling this one tomorrow.
    Any idea as to what the diodes do?

    ReplyDelete
    Replies
    1. This is what Clay Jones wrote about it on FSB a few years ago and he's considerably more clever about these things than I am!

      "At dc the diode placement is irrelevant. At Q1 the reverse bias just sets the thing at a (perfect world) infinite resistance. Open. It couldn't care less at dc. Q2 forward biases in the same old same old shunt clipper way...just slightly varying the operating point. Blah.

      At ac the the diode placement is trivial. Any negitive swing at Q1 just ignores the thing, like it wasn't even there. Like it was just one big damned resistor. It moves on down the line. The upswing is only impacted providing that the gain at that point is enough to send the diode into conduction. That's the reason for jamming the diode's anode into the junction at the emitter pot wiper and the bypass cap. It's just taking advantage of the gain characteristics of the bog standard FF setup rather than limiting that section by strapping it straight to ground. Any positive signal level less than the forward conduction magnitude of the diode just goes on it's merry way flapping against the base. In that case, both signal sides flap away like any other entry level transistor amp. The diode may as well not be there. Any upswing signal that sends the diode into conduction will chop the top like any run of the mill clipper clipping at whatever level it clips. Again, same old same old. The bandwidth gets flattened and broadened, the rolloff point gets lowered and earlier frequency 2nd order harmonics crash up against the break point etc. etc. and all that other mystic shit that happens at clip levels...

      Q2... meh, again. Reversed biased negative swings couldn't care less. Forward biased positive swings clip at a slightly altered operating point, riding above the threshold to ground level. pfft. The whole thing is an assym clip with an approximation toward "symmetry" happening at higher input levels. Push harder at the input and vary what you might call the transconductance characteristics. A typical FF does this anyway. This is just some doinking crap mod which creates barely noticable alterations in the operating points. I say barely noticable... sure, whatever. It's enough apparently to send the TGP type crowds into orgasmic circle jerking ecstacys of self congratulating patheticisms of how great each other's "ears for tone" are. No doubt in my mind either that there's [self edit to tone it down some...]

      Uhh... yeah, sure. Nothing special really... just another slightly modded FF."

      Delete
    2. I sort of get it. I expected it to be more of an "intentional mismatch device", creating an extra voltage drop across the diode (explaining the mixing of Ge and Si)... but it's just wankery at the end of the day (which Fulltone's not lacking in!)

      Which transistor should be the higher-gain one (left or right)? I'm a bit confused.

      Delete
    3. I know Mark, beats the fuck out of me! :o)

      And Ross, I didn't use the transistor symbol with the BC108Cs having the triangular pin layout (and so any pin configuration is easy to match on the board by just rotating it) but I forgot to mark out which was which. The bottom transistor is Q1, and that should be the lower gain one as per the usual Fuzz Face selections.

      Delete
  3. One other thing before anyone mentions it, the Fulltone 70 schematic has a 1M pulldown resistor from the volume pot output which I have omitted because I can't see the point of it when the pot is performing exactly the same task. All it achieves IMO is adding a 1M resistor in parallel with whatever the volume pot is set to, and so when at full volume for instance the 1M is put entirely in parallel with the 250K pot, which just gives you a 200K pot with a slightly weirder taper.

    If you really want to include it, just solder a 1M resistor between lugs 1 and 2 of the volume pot, but I don't think I'd bother.

    ReplyDelete
  4. You can call this one. It sounded great in my initial late-night-quiet-so- the-family-doesn't-wake-up test. I ended up using the 2SC1815 / BC550 trans combo suggested by Ross. I didn't have a 1KC so I used a 1KB and all the fuzz is in the last 5% of rotation. I will replace that one for sure.

    ReplyDelete
    Replies
    1. Nice and quick verification, thanks mate, and you too Jon :o)

      Delete
  5. I can Second this Build. I noticed on the BC108 Data Sheet BC107 & BC109 are similiar. I used BC109. Also it is Best with your favourite Booster Pedal in front of it to get all the Radical Fuzz Sounds. Also note the legs of one of the transitors is Crossed ie ECB instead of EBC. I also just used 1K B instead of 1K C for the Fuzz Pot. Thanks again Mark for putting up this Pedal. Much Appreciated.

    ReplyDelete
  6. Looks like fun! Any ideas of hfe a I should be looking at?
    Cheers

    ReplyDelete
  7. Hi, Mark! Fuzz work with BC108B?

    ReplyDelete
  8. Hi mate, I just finished building this and I've gotta say....wow! I ended up using a 2n2222a for q1 hfe 200, and a bc109c for q2 hfe 420. Sounds great. I've got an original fulltone 69 at home and this 70 rips it to shreds. I guess I like my fuzzface with a sprinkle of silicon. Thanks for your awesomeness!

    ReplyDelete
    Replies
    1. Great info, thanks for that Jeff and glad you like the build

      Delete
  9. I've built this as well... 2N3904 in Q1 and 2SC1815 in Q2 does not work well at all. I'm going to run out and grab the equivalent to a BC183 today, as that worked quite nicely with my Meathead. From what I've heard, this one's a bit darker and dare I say a bit more polite than the Meathead, which is probably my favorite FF-style pedal.

    ReplyDelete
  10. Maybe this was asked before and i overread it... but do you need to match the BC108c's or check them for the right hfe values/leakage currents etc?

    Or should any stock BC108c hfe 400-800 do?

    ReplyDelete
  11. I've just built this and no matter how many transistor i change...sound just the same!!
    Bc108 a-b-c ,2n2222a, Ac/dc Adsl ,ZZTOP, U.s.a, U.s.s.r etc etc...It sound the same...super higain...
    and if i lower the gain or the guitar volume pot sound terrible.
    Obviously something got wrong...any suggestion?

    ReplyDelete
  12. Ohhh i forgot...Mid Pot does have no effect

    ReplyDelete
  13. just built this one last night with two BC109C's. it sounds great. I also added a 'bias' (B50K) pot on the input borrowed from the '69 so I can get a little brighter tones when the the fuzz knob is at lower settings.

    ReplyDelete
  14. got mine completed and boxed. it sounds awesome. here's a pic of it.

    http://johnkvintageguitars.homestead.com/Effects/Fulltone/70/70pedal-01.jpg

    I also own an original early, large box version of fulltone '70 and I gotta say that I like my clone a lot better than the original, mostly due to the added 'bias' (input attenuation) control.

    ReplyDelete
    Replies
    1. Awesome!!
      Is that hamertone-paint or powder coating?
      I'm also very interested to know how you got the white graphics on there since i had about the same idea for a box.
      I normally use waterslide decals and i can't print white on them :(
      (Great site by the way)

      Delete
    2. I never get my hammertone finishes (spray or paint) that nice. I'm jealous :)

      Delete
    3. it's a powder coated enclosure. the graphics were done with a p-touch labeler.

      Delete
  15. I just tried an NPN germanium in Q1 (with an hfe of 242), with a BC109C in Q2 (hfe of 520), and I like it even better now.

    ReplyDelete
  16. I've just got all the components together to built this one. Just one question:
    In the schematics i found the 2u2 cap is a 22u cap.
    Not that i'm not gonna try both, but what should be the overall difference?

    ReplyDelete
  17. As a matter of fact... there are also some differences in the area around the MIDs pot (1K and 220R) and the 47u which is missing. Makes me think i haven't found the correct corresponding schematic :S

    ReplyDelete
    Replies
    1. MIDs pot area thing solved!
      The order of the 220R and the 1K pot parallel to the 1K is reversed in my schematic but should result in the same resistance.
      :)

      Delete
    2. Can you send me a link to the schematic you're doing it from. I did it from this one:

      FULLTONE70CORRECTED.jpg

      Delete
    3. Thanks,
      I think i had the UNcorrected version of this one :)

      Delete
  18. Is the 3rd lug on the mid pot not supposed to be connected to ground or something? I've built this circuit twice and I'm still having trouble with it. I get hiss when I turn the mid pot, but otherwise no sound when the effect is engaged. I've check and rechecked and I'm fairly positive that everything else is correct, but I suppose I could be missing something.

    ReplyDelete
    Replies
    1. No, if it was supposed to be connected to ground it would have been shown on the layout. It's being used as a simple variable resistor so only 2 lugs are used.

      Delete
    2. I guess some times you just have to walk away, pour a glass of scotch, and come back to it. I misplaced on of the leads on the 22uf cap. It's a little late for me to really take it through it's paces at the moment, but from what I can hear I'm really digging it! I used these bc108s from small bear and it sounds great!!

      http://www.smallbearelec.com/servlet/Detail?no=1199

      I haven't amassed a huge stock yet, but I have a few other NPN transistors lying around and I'm really stoked to swap them in tomorrow and see how it sounds.

      Delete
    3. I'm really happy with this pedal for the most part, but I'd like to brighten it up a little. Could I do this by swapping out the 100n cap for a lower value? 47n maybe? Or could I possible change the mids pot for another value? It's maxed out and still sounds a tad bass heavy to my ears.

      Delete
  19. Got it on breadboard right now. i Think it sounds the way it's supposed to :) Anyway it sounds great to me.
    By the way, I have connected lugs 2 en 3 of the Mids pot.

    ReplyDelete
  20. Strange, i got the circuit soldered together and now it squeels on high fuzz and volume settings. can't quite remember that was the case on breadboard.
    But then again, reading the description above that is to be expected.

    I did change Q1 for a much lower gain 2N2369A (typically around hfe of 60) and that made it sound a little "friendlier" ;)

    ReplyDelete
  21. hey guys i have finished this one and i do really like it, enough to kick my mxr classic 108 off the board however i was wondering if someone could help me out with some mods, basically the thing is just too loud for me, even at the lowest vol setting it is well above unity and as i increase the mid pot it gets much louder (and i like the sound better) basically it just doesnt fit into the volume profile of the rest of my board, so if anyone could give me some ideas of how to tone it down a bit it would be much appreciated.
    cheers for the layout

    ReplyDelete
  22. I have the second edition of this footpedal and it doesn't have any diodes in it whatsoever and the transistors are 2sc828. It sounds good to me. Are you sure there were diodes in the original?

    ReplyDelete
  23. starting sonn trying it with metal cans q1 2n2222a, q2 bc109, and 1n270.

    ReplyDelete
  24. Check the list, found just 5KC - Rev Log POT... does it will work or are there a better solution?

    ReplyDelete
  25. Fulltone 70, no connection for Mid Lug 3 ?

    ReplyDelete
    Replies
    1. Correct, it just acts as a variable resistor. You could link it to 2 if you wanted, but you don't have to.

      Delete
  26. This is my first build using layers from this site. It worked on the first test. Sounds nasty - the good kind. Right at Fuzz 10 it blows up - I've been playing it for two hours with all three knobs cranked through a BF Pro Reverb. Great fun.

    ReplyDelete
  27. Complete this one today with the bc108c, i se no much diference on 5k trimpot, sounds good anyway. It can be evil at full gain fuzz. The mid knob is some kind of presence control... adds some volume too.

    ReplyDelete
  28. just finished to build one... And it worked great! except i mounted the pots reversly... ;)

    It's my first built with a Vero! So happy :)

    Thanks for this blog!!!!

    ReplyDelete
    Replies
    1. Great, and it worked that's the main thing!

      Delete
    2. here's a picture

      http://alborea.free.fr/Telechargements/diy/IMG_0345.JPG

      I'll make some sounds too!

      Delete
  29. Build this yesterday night... it already sounds amazing straight into my interface at low volume! Can't wait to play through it into my actual rig!

    Just a quick question about the trimpot. Is it used to just find a sweetspot in the fuzzrange (that's what it appears to be doing when I turn it)

    Or is it to set an exact value? I've read somewhere it's used to get 5,5V to the collector of Q2... that right?

    Thank you!

    ReplyDelete
  30. built this yesterday. I get some fuzz out of it, but at low volumes (full volume is about as loud as my clean signal). Cecked for bridges, polarity, etc. and looks fine. Could it be down to the diodes? i used two 1N4148. should i try a 1N60 in the D2?

    ReplyDelete
    Replies
    1. 1N60 would have a closer forward voltage but that wouldn't make it any louder. Check the voltages you're getting on the transistor pins and post them

      Delete
    2. Checking the voltages i noticed i had the B an C pins of the upper transisor mixed up... Can't believe i missed that. Sounds great rightaway, a tad harsh though. Brooding on some artwork now, i'll post a pic of the end result!

      Delete
    3. And there we have it. As a bit of a Lebowski fanatic, volume can be marked 0-8. https://fbcdn-sphotos-f-a.akamaihd.net/hphotos-ak-xpf1/v/t1.0-9/10710790_10154636238020301_3244660603499144752_n.jpg?oh=e72a7e605318e187c2cd56460cec792b&oe=54CC69E8&__gda__=1422404759_1f8b7ae51c00427fed38a2712a489036

      Delete
  31. Built it - the trimmer seems to do very little, so does the mids pot...it seems to do nothing!!!
    Renegadrian

    ReplyDelete
  32. Took the freedom to use Mark layout as a starting point to develop a new one, this time with the regular CBE legs orientation, no need to twist them! You can find it at THIS LINK HERE - Renegadrian

    ReplyDelete
  33. I've built a few of these now but this time I couldn't settle on a transistor for Q2. So I put in 4 using 3 3PDT toggles. 1 for each pair of transistors and one to select between the 2 pairs. So now i have a BC109C (stock), a BC549 (modern sounding), a MP37 (squidgy mid bite) and an AC127 (does't bias correctly so sounds very gated and synthy). Happy camper here.

    I used 1N914s for the diodes and replaced the trimmer with a 2K7 resistor. Never really made much of a difference in my other builds so I didn't bother here. Also toying with replacing the fuzz pot with a fixed resistor as you get better results cleaning it up with your guitars volume pot.

    Once again...cheers lads.

    ReplyDelete
  34. So the mid knob is just a bias adjustment for Q2? And even at maximum it will fall short of the "basic" fuzz face range meaning it is being ran at a higher voltage than normal which will definitely make it louder and bring out the mids. That explains a lot.

    A higher value trimmer will most likely tame this thing down to be more creamy and squishy and fuzz facey. For me it was way too raw and the volume pot cleanup is just ridiculous. And it's no wonder at this bias point. It will definitely sound better cleaned up if biased colder. Fuzz face is not supposed to sound like a rangemaster when you clean it up. I'd but a 5k trimmer there and find the right point.

    ReplyDelete
    Replies
    1. Although doing this might make the mid-pot useless. Maybe it's better to just swap the mid pot for a 5k.

      Delete
  35. This comment has been removed by the author.

    ReplyDelete
  36. Mindcrime, I noticed the layout you posted above doesn't have a 47u cap. Is that okay? I'm new at this and thinking about trying to build this.

    ReplyDelete
  37. Just built a copy with simple BC108 (I don't have 108C in stock). I get a very low gain output, it does not even getting very fuzzy. Do you think that higher gain BC108C will solve this?

    ReplyDelete