Tuesday, 29 July 2014

DAM FZ-673

Request.  Info about the hugely expensive final price "can only buy in limited numbers from eBay auction" David Main take on the MK1/ Zonk (7 out of 10 of which are probably in glass cases and haven't been plugged in yet).

I am the fuzz box system demon ~ FZ-673

The beginning. I’ve been brewing this thought for a while and a few favours owed made it finally manifest. In fuzz box terms I guess this is an embodiment of old school and new school, or at least an attempt there of. Basically, the FZ-673 circuit is the Zonk Machine/Tone Bender MKI circuit with a few subtle tweaks to try and make what is a pair of clown sized dinosaur shoes into some kind of laser beam driven UFO controlled fuzz device.
The simple new happenings are, the addition of a tone filter, a boost in output volume and gain plus your handy modern day fixtures of an status LED, battery drawer and DC tap.
The one grander thing I’d been messing around with since I was doing the Holy Roller (the D*A*M MKI style fuzz box circa 2004) was to get that particular circuit to yield not only a lot of gain at full-bore but also to be able to deal out some elements of clean-up and ability to lay down a tone that one would almost describe as an overdrive tone. In essence I was scrubbing out all the heavy decay and choppy gated artefacts that generally occur with this circuit type leaving the user with a purer fuzz tone. I would like to boldly declare this is what you get in the FZ-673. The best of everything, High gain, instant clean-up, but, this fucker needs to be stable, as in, warm. Feeling hot hot hot? Its not like you’d need to keep it on a heat mat or have a hot water bottle permanently gaffer taped to the enclosure but you will hear a significant move in gain in colder climates. It’s nothing that would cause any major headaches but it is a common theme with original MKI circuit types, to hear shifts in the output due to heat, and I do need to mention this point.
I’m basically saying, this pedal will give you op-amp quality overdrive like smoothness but with all the complex glory and freaky exhaled responsiveness of a primitive germanium fuzz circuit…but, only when its been let to adjust to its environment. I’m over emphasizing this point I know and I’m mainly talking about when the pedal is either first unpacked or say moved between different climates or environments.

Popping buttons

The controls are pretty straight forward but there are a few things that need to be understood. The Swell is basically your volume control but its nature is different to a regular your volume adjuster. At around the noon mark it tames a lot of the high end content you’ll hear when you have the filter set to full treble (fully dialled to the left) Inching past noon, and more obviously in the last quarter of the turn, the Swell will really push the gain and overall saturation levels and deliver you a pretty fierce fuzz tone, once the Fuzz control set wide open. The Fuzz control is a lot more ‘normal’ in its delivery of tones and the amount of sustain it lays down than a stock Zonk Machine Fuzz control would offer you. You have a pretty decent gradual increase from chunkiness to full-on fuzziness and little in the way of dead spots. Zonk’s can be either all on nothing at times in this regard. Temperature extremes will affect this dial usage too. A cold winter’s day and the Fuzz dial will need maximising for the full-on fuzz experience. Baking in a sunnier environment and set at full Fuzz the FZ-673 will be stripping paint.
Filter is just that. Nothing overblown just a very crude, but at times pretty damn effective dial for tuning your guitar and/or amp the FZ-673’s circuit. Pick-up type seems to really come into play here and more obviously so cabinet size. P-90’s respond really well and lay down a healthy jumbo sized thick tone with the Filter pushed open. An open sounding mid gain single coil (P-90’s get my vote) seems to do the do and with spare change.

Made from Stars

The construction style you’ll find somewhat familiar. I dig it so I dug it. Only the second time I’ve used a two layer graphic and I’m pretty stoked with the results. It’s pretty new in that regard. The theme? I was aiming to manifest a sci-fi kinda thing, got pretty close I think. FZ = Fuzz. 67 = 1967, the (guestimated year) of the main study Zonk. 73 = Year of Enter the Dragon…and Black Mama, White Mama…irrelevant shit to finish of the name to be honest. I actually wanted to make the finished item to appear almost toy like, kinda like it was made from Lego or something along those lines. The original plan was to use red chicken heads but I think the boundaries of good taste with a dose of humour had been exceeded in that case.

Transistors. Military shit all the way. The Motorola OC75’s I was told were ex-military stock so I combined those with CV7004’s (the military version of the OC45). The little fat UFO style cans of the Motor 75’s had the tone and looks and I thought it made cool and some what geeky change to the usual suspects. I threw in some old school flavours with the capacitors too as to top that whole vibe off…and of course makes it all tastes betterer.









38 comments:

  1. Ok, I'll ask first. What to sub for the insanely priced OC75 and CV7004? No wonder these sell for $2000 on ebay... the transistors alone cost... uhh... $40.

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    1. http://alltransistors.com/

      I'd suggest cross referencing OC75 and OC45 (fuck that military spec shit). Find some good (relatively) cheap Russian germs and build a kick ass pedal that would probably rival DAM's transistor choice in all but the "biggest dick" category.

      Mojo is awesome... until it's retarded.

      Other suggestions are:

      OC75: NTE102A, 2SB175. Also I've twice bought $15 high gain germanium transistor packs from gutiarpcb.com and got 5 great hand tested germs per pack. It's not bargain basement, but it comes from a super reputable vendor.

      Out of those two packs I got HFEs of 160, 176, 190, 191, 195, 212, 218, 224, 232... 4 of those would easily replace an OC75.

      OC45: I've got a bag of MP20As for less than 2 of these, plenty of which measured over 50 hfe with very decent leakage. They work great for me.

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    2. Forgot to mention, all of those germs from guitarpcb had near zero leakage.

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    3. Never knew about alltransistors.com... thanks!

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  2. Wow... after reading that insanely pedantic blurb I'm convinced this guy guzzles his own kool-aid.. which is a mean feat seeing as how he sounds like his head is right up his ass.

    Sorry if I offend anyone, but it's a fucking fuzz pedal and this dude talks like it fell out of Jesus Christ's robes.

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    1. Agreed, and probably another builder who would claim the hype is not of his making whilst deciding to sell a limited number to the highest bidder. It obviously works for David but I'll never buy into collectors items.

      For the transistors just try something a bit leaky for Q1 and Q3 and go from there. You don't need $40 transistors to make a great sounding fuzz.

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    2. I'm with you there. I won't use or buy or build a pedal if it getting kicked across a stage would bother me much. I'd be terrified to take a $2000 pedal on stage and it would be absolutely useless to me in a plexiglass tomb somewhere.

      Maybe some people buy them for studio use only? Still seems nutty to me.

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    3. I have made one of these from another layout using some random transistors and it sounds amazing... I have used... OC75s, AC125s, and also Russian transistors, also OC76s and even small bear TB1 set that had some AC128s. Bottom line - I have not settled on THE set yet because everything I toss in here sounds amazing to me and after a while it gets to be crazy - with that...
      Mojo Smojo... Grab a big pile of transistors and have at it! Important to make sure you get Q2 stable. Great layout Mark! I may have to make another one of these with your layout since it makes more sense to me then DAM's layout :D

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    4. Oh yeah, for the 1n cap... I suggest using a polystyrene capacitor if you can...
      CHEERS!

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  3. built it but something's wrong.while adjusting the trimpot it fried my trimpot twice, and two different OC75's (in Q2) are now shorted (dead).

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    1. I don't want to keep frying the few NOS mallard OC75's that I have left so I think i'm going to pass on this one.

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    2. hmmmm... that is scary!

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    3. this was the layout I used before with no issues
      http://2.bp.blogspot.com/-H1BfOBi-Xzw/T2eRuEc7OCI/AAAAAAAABKA/hOY9aVF9Cx0/s1600/fuzz673rev2.png

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  4. okay, to be safe I tried it with some AC128's (which I have tons of) and it works perfectly now so you can verify it.

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    1. pic of the working (and verified) board. i'm using two Mullard OC75's (Q1 & Q3) and an AC128 for Q2.

      http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/DAMez/DAM-FZ-673-Board.jpg

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    2. Do a layout, go to bed, wake up and layout is verified. Yeah! :o)
      Thanks for verifying matey

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    3. John:

      Did you build it stock, or mod it for bass at all?

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  5. One of the best fuzzes I've ever tried. It's picky about the trannies, but more forgiving than the Tonebender MKI.

    This is a pic of my unit, built in 2013:

    https://scontent-a-mad.xx.fbcdn.net/hphotos-xpf1/t1.0-9/1476035_10201687309217037_1258701234_n.jpg

    J.

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  6. I never liked the marketing blabla no matter if coming from a big company or from a little manufacture. As a player I don't care how the sound is achieved inside the box. If chicken crap can sound good, then use that. Of course as a hobby builder I'm intereseted in how things work, but then when it turns out that actually a few bucks worth of components are producing the sound that is described like the holiest thing on earth... well I find that rather ridiculous. Even if the sound is indeed pretty good like in this case.

    And now the question: what hfe do you recommend for the trannies? I have a small batch of AC125, would try that if I find suitable hfe among them...

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    1. This build is not really related to hfe, or to be more correct, not mainly to HFE, but leakage in different positions.

      Google "Zonk machine transistors" and you'll get many tips and webs dedicated to this topic. So, be prepared to try / check dozens of trannies. I'm afraid that a small batch will be not enough.

      Regards

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    2. Thanks, Javi. After a little google search I've found a very good writing on geofex from R. G. Keen: http://www.geofex.com/Article_Folders/zonkmach/zonkbst.pdf, at the end he describes how to tune the effect for your trannies. From what I understand you can use pretty much any transistors with the hfe about 100 and low leakage, you only need to tweak some resistor values to get them working right.

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    3. Yes, is one of the solutions, to simulate the leakage with resistors. For example, in the Zonk, if you want to stick to the circuit (what is recommended to get th real sound) for Q1 you need an extremely leaky trannie to get -3 or -5 volts on the emitter, we're talking about 1000ma or even mor, and a HFE over 70-80..

      You can simulate ir with the resistor from ground to base, but if you do so, and after you get a trannie of this kind (not difficult, surely you'll have lots on your garbage and unusable germanium trannies bag :P), you'll see that the sound is way different to the simulated with resistors.

      For Q2, and Q3, nearly anything with 100-110 hfe and ~200-300ma leakage will do the work fine.

      Regards.

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  7. I think most of us that have experimented with Zonk/MKI have read Keen's article and have tried to tune it with trimmers

    I recommend not going down that road. Build it with fixed resistors and tune it by swapping transistors

    I could never get it to sound good with the trimmers. They actually just add an extra element of confusion for me.

    This isn't really a build to worry about hfe and voltages too much. You just have to use your ears

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  8. hi, I recently bought a lot russian germs but none of them have leakage above 1mA. Also the few ac125-28s that I got have almost no leakage. Where (and which type) can I get some good leaking trannies?

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  9. Ok I was confused. Javi mentioned leaking of 1000ma and I only got readings about 0.08 mA on my DCA55. But javi meant micro with his 'm' and the DCA means milli with the 'm'?
    The effect sound pretty good already but the sustain could be better (I should probably check more trannies). Also one pot acts strange so might need to change that one..

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    1. Hi, to make things correct :P I recommend a leakage of 0,800 -0,900 mA for Q1 and an HFE of 60 to 80. Yeah, the kind of trannie that you throw to the bin when you see the reading in te Peak :P

      That's the only way to get 2-5v on the E of the trannie, and a hfe of 60-70 is right to push hard enough the rest of the circuit..

      On the other hand, the sustain in the MKI is very short, nothing even similar to the MKII. You have to look for a short sustain, bbut with clean and progresive decay, no sharp decay, atifacts or any other noise.

      It's a really aggresive sounding fuzz, but not many people's cup of tea, and very different to the MKII or MKIII.

      J.

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    2. okay thanks a lot !!

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  10. Could this be made using silicon transistors?

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  11. In my opinion, no. At least not if you want it to sound good.

    This circuit relies on leakage to bias the transistors. Take the leakiest germs you have and try those

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  12. I boxed this finally. It sounds pretty sweet with these AC125s. It has some gating, but no crackles :) I'll keep tweaking bias and swapping trannies, but for now at least it's by far the best MKI I've built

    http://i825.photobucket.com/albums/zz176/Dub-T-123/0680DFAA-37DF-4A7D-8917-BD97C00DC220_zpsbeezmep0.jpg
    http://i825.photobucket.com/albums/zz176/Dub-T-123/B69D192D-906B-4A7C-97C9-5E2B5B5A9D4E_zps7cxmsr9d.jpg

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  13. Thanks Mark, after some experimenting I've finally arrived.. I'm never selling this pedal! It's taken me so many failed attempts at MKIs to finally be satisfied by the sound.

    So this one is a big success for me. It really sounds great.

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  14. Hey all...
    I built this pedal with this layout using a leaky OC75 for Q1, Q2 is an AC125 that is not leaky and Q3, another leaky OC75.
    And I cannot believe without any issues, fired right up and it is simply amazing!
    My only issue is, are these MK`1 tone benders darker sounding then say a MK II?
    MY other fuzz pedals are way brighter for sure...
    I run it into an overdrive pedal set to a clean boost however and I am just blown away at the sounds I get... Attack pot has no DEAD spots, no screaching... love the decay you get.. a truly 60s fuzz
    Thanks IvIark for the great small layout!

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  15. I just built and tested this and appear to be having the same problem John Kallas initially noted for his build. The trimmer basically went up in smoke after I adjusted it while playing. Before that it had a weak sound for just a minute or so. Does the trimmer cause internal shorts in Q2 easily for some reason? I've confirmed parts values and orientation, conformity to layout, etc. Any thoughts would be appreciated! Thanks for all you do with this site.

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  16. I would first check all of the cuts on the 3rd row from the top. Make sure there's no continuity where there shouldn't be

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    1. Thanks, I will try that out. In general is it okay if all legs of the trimmer are soldered in?

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