Sunday, 26 August 2012

DAM FR70 FuzzRong

Info from David Main about his original:

We begin with a re-cap. The FR-69, our take on the early bird Mosrite Fuzzrite. The germanium powered glass shattering freak show. As stated on the page for said pedal my only real interest there was because of the awesomeness of Ron Asheton and the Stooges. In other words, there is no real nerd obsession with the pedal itself. Thanks to a trip to London a visit to a Soho's Original Bookshop and the discovery of Robert Matheu's outstanding book on the Stooges I think it maybe wise to dispel the "Ron used a Fuzzrite" myth once and for all, that is until someone shows me a picture of Ron actually using one.
Robert's fine book has several fine shots that clearly show Ron actually using a Vox Tone Bender. Other photographic material that can be sourced on the internets show Ron with what appears to be a Marshall Supa Fuzz. Either way, it ain't no Fuzzrite. In a nutshell and in my head at least. Dig the early Stooges fuzz tone? Get high, get a Vox. Simple.

So what has this gotta do with the FR-70? Not a damn thing. Just explaining what we ain't doing here. So this new Fuzzrong is...? Outta the whole Ed Sanner family of pedals and the different versions produced the one I always had a genuine soft spot for were those made with the freaky little orange encapsulated Sprague circuits. Louder, chewier and with mightier balls. I've always been fond of the general sickly thickness and the almost psychedelic nature they seem to have. This is basically our salute to the those funky little orange packages of filthy fun.

Operation scratch 'n' sniff

Like with all good workings it began with a sacrifice. An offering to the Fuzz God. The pre-selected healthy young virgin was carefully dissected to reveal the inner workings and the bounteous gifts of the unknown. With much suffering and toil the knowledge of the highest degree was gained. Our dissected orange goddess became the starting block for what you see here. The FR-70 is not a direct clone but and very gentle tuck and re-shape. It's difficult to generalize too much as the Sprague modules were not or at least don't appear to be 100% identical tonally when in use. Like with any discrete fuzz circuit you will always have some play or movement in the delivered fuzz tone. The sacrificial lamb was an example I found particularly pleasing. The gentle refinements then move it into a somewhat more balanced state that aid reproduction for a more modern parts selection.
Constructed like her greasy twin sister the FR-70 uses the same methods of assembly and the same principles of design as the GB-83. Specially selected silicon devices are the foundation to the whole circuit. Very precise gain levels had to be matched and then reproduction to achieve the desired balance in tone. The same detail is then applied to the whole pedal. Basically every component and part is selected for overall sound quality and performance.

Psychedelic goose fat

So the tones from within the tin. The first thing to note compared to the FR-69 is that the overall operation is more stable. The gain spread on the Depth control is much more even with a greater extension of the mid and low frequencies. The general position that the FR-70 takes is an offering of tones that are situated in the low mids with a punched out boost over into the highs. It's not quite scooped as such but a subtle high and low kick is dB boost is apparent. The gain and sustain levels are also more stable and maybe more user friendly. For example, the FR-70 is not a screamer from the get-go. Again something shared with the GB-83 is that you have to put the work in and use the right gear to get to your destination. The FR-70 does have the where with all to get fatty and rancid with some pleasing fuzzed-out compression but the subtleties are also an important factor in my head so the ability to draw pretty flowers with trails of magic dust is there for the taking too. I guess like the GB-83 it is somewhat tool like. It is a fuzz generator but you have to give it the instructions. Not quite a blank canvas as such but fully able to work with and around you. It's sick & rong but only as much as you are, my dears.





Compact layout:




Mojo layout:


36 comments:

  1. Oooh! DAM Stuff...I've had to order the KSP42's from China so they'll be awhile. And the others from the UK. Do recommend any other transistors in both positions for the meantime?

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    1. Looking at the gain, the KSP42's look like they may be other brand MPSA42's, and the 2N4401 has the same gain range listed as the 2N3904. So there should be plenty you can experiment with there.

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    2. Settled on MPSa18 and 2N3903.

      Sounds good, The thin/raspy sound at minimum depth is cool too, especially on the dirt channel. Might want to label the volume 2 to output too ;)

      Cheers mate.

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    3. That should of read '2N3904'.

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  2. DAM designs never fail! Tag it.

    For transistors, i used 2N2222 for Q1 and BC338 for Q2. These work like a charm. As a little mod, someone would probably want to change the Depth pot for something like 200K or 250K, as the setting in 0 is really thin and bassless. I also added one trace cut 2K7 resistor to the first row to accomodate the LED :)

    +m

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    1. That was quick! Nice one Miro, and good idea about the LED resistor, I don't know why I forget them sometimes when there's plenty of space!

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    2. No problem. I've come a custom to adding led wiring to the dc jack, but sometimes it's good to wire it to the board if there is room to do that easily. Sometimes i take two wires to 9V strip - one to power source and other to the LED resistor..

      About the transistors. I'm not sure why Q1 is a high voltage device. Maybe that's supposed to sound "bigger" with small voltages. What i learned from my circuit is that for Q1, anything BJT silicon at 75-150 hFE works perfectly, and for Q2, anything BJT silicon at 300-400 hFE is good. I tried a few different sets, but those gave me the results i liked. My 2N2222 TO-18 measured ~120 and BC338 TO-92 measured ~360.

      By the way :) The unverified tagboards may get verified faster, if you add vero to them as a option :) There are a few interesting layouts there, but i find tagboard clumsy to build. If i recall correctly, there's something like 5 unverified left.

      +m

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    3. I think Q1 was selected for its extremely low gain

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    4. I tried something with 40-50 hFE in there, but it didn't produce fuzz. Sounded more like a real bad fart.. 120 may be a bit too much, but i have a gut feeling that it won't sound any good under 70 hFE... Don't know, but my circuit works a charm and sounds really good :)
      +m

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  3. Hotttt!
    Thanks a million for this!
    I started building 'cause of the Fuzzrite family. If this sounds as good as the clips, it's going to kick my Fy-2 off the board.

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  4. I wasn't planning to do this because I didn't like the sound of the clip, but I was bored and the parts were such that I didn't have to order anything and wait a few weeks to get them. But this sounds really good. I used a 2222A for Q1 and 2N4401 for Q2 (I tried a bunch of combinations.)

    The only other sub was a 500kC for the Depth. I don't have a 470k handy and I seem to have accumulated a number of reverse log pots from various failed or disappointing projects. mirosol is correct that the 0 setting is useless, but the reverse makes for a pretty smooth transition.

    Anyway, thanks. This one will get boxed whenever I get wround to buying some enclosures

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    1. How does that sound, Piltdown? I have a 500C left from a DOD250 project that kinda sucked. Not bad, just not good, that one.

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    2. It seems to be fine. I think it's a smoother change over the spectrum than the non reverse pot. But I don't know how different it sounds from a 470. I have a number of them so I figured I'd put them to some use. What's the worse that can happen, right?

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  5. I have a general question: can you use a metal dc jack in a metal enclosure? The box is ground, and the outside of the dc jack is positive (center negative). Is there a trick to do this or can you only use a plastic dc jack in a metal enclosure?

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  6. You could use that with a positive ground effect but not here. Unless you somehow isolate it from the enclosure

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  7. Okay, where is depth 1 going to? To ground? It's usually coming from the emitter of Q1 through a cap on these style pedals!

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  8. Depth 1 has no connection, the pot is used as a simple variable resistor

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  9. i meant the collector (sheesh). Thanks, I guess it is a bit of a redesign after all, not a simple component swap. Great job, D*A*M!

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  10. Hi,
    I am a relative newbie to stompbox building, although somehow managed to get an orpheum fuzz working?!Anyway I wanted to build a fuzzrong clone, and followed the one on turretboard website. I followed this exactly, have checked and re-checked but cannot get it working. Have looked at your version which differs in quite alot of ways, more components, layout etc. I see your version has been verified, and would like to try it. I was wondering if someone could help me with the wiring to the footswitch and pots, a diagram would be great, or just advice, really appreciate it, love this site! Ta from England! Pete

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    Replies
    1. Hi Pete. I'm from England too, so hi from Manchester! :o)
      Have a look at this post, this will show the switch wiring and how the pot lugs are numbered:

      http://tagboardeffects.blogspot.com/2012/02/offboard-wiring.html

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  11. Hi Ivlark, brilliant thanks a lot, just across the border in yorkshire near bradford, cheers!

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  12. http://mirosol.kapsi.fi/varasto/boxes/wrong.JPG

    Love it. Like all DAM circuits.
    +m

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  13. Just built this guy. Sounds great. I used a 500k pot for Depth. The entire sweep is very usable. Not a bad sound to be found in this box. I do wish it was a little nastier and splattier though. This is definitely more refined than your average 60's fuzz.

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    1. Just saw this post. I snipped the 220p cap, but I could not hear any difference. Am I deaf? Haha. Anyway, I very much like the sound of this as is. Quite similar to the DAM Drag'N'Fly I built earlier, but with a touch less gain, and a bit more clarity, even though there seems to be a bigger bass presence in some way. Sounds awesome for buzzy single note lines on the D/A/E strings.

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    2. Alright, so while boxing this thing up, I realized a few mistakes i made. Now the things sounds as it should. Buzzy tone for sure!

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  14. Just finished, sounds great. With David, my faith in silicon fuzzes is getting bigger.

    Used a MPSA42 rated 95 hfe for Q1 and a 2N4401 rated 300 hfe for Q2 (stick to specifications, KSP42 and MPSA42 are the same trannie, different manofacturer).

    Definetely, with D*A*M effects you can't go wrong, anything will sound fantastic.

    BR

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  15. And here's the 7th Dwarf :P Next one will be in a 1590B. It could fit with no problem, but for a time, I need to forget about the manifiying glass :P

    http://www.facebook.com/photo.php?fbid=430150187056835&set=a.404470492958138.93220.404417189630135&type=1&theater

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  16. Work perfectly with two MPSA18, gnarly enough, i love it.

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  17. Played around with this as the one that was a keeper got accidentally sold:(

    So i came up a slight mod. The first 40% of the depth was imo unusable, making the circuit sound like stock 66 tonebender - thin and piercing. Which is without a doubt a feature in the original. But i wanted a bit more balls to it. So i ended upping the 1n for 6n8 and lowering the depth pot for 250K. Didn't do anything else, but i think that upping the right hand side 47n for 100n could be worth a try too.

    Put 2N2369 for Q1 and 2N2222 for Q2. Loving it.
    +m

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  18. I started building this and realized I didn't have any 470k resistors, so I socketed those holes and twisted pairs of 1M in parallel and used those in place of them. It looks ridiculous, but it sounds really awesome!

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  20. I had some mpsa42's i ordered from tayda... upon closer inspection they are actually labelled ksp42! sounds killer with ksp42 hfe 120 and 2n4401 at hfe 265.

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  21. Ordered a KSP42 especially for this one and must say i am not disappointed by my decision. The depth pot gives a great blend from a really nice fat fuzz with it fully CW and a real thrashy fuzz fully CCW and all the resst inbetween. Likey Likey!!!!!

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  22. Built today using BC108-B (T1) and 2N2222 (T2). Sounds fantastic, versatile and useful pedal. Thanks for posting.

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