pimp behringer sf300 superfuzz with univox superfuzz mods

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pimp behringer sf300 superfuzz with univox superfuzz mods

Postby tabbycat » 01 Sep 2014, 23:57

pimping my behringer sf300 superfuzz with univox superfuzz mods.

sf300.jpg

happen to have a spare of these pocket-money pocket rockets that i want to pimp.
even though i'm fond of it as it is. proper raunchy. not far off the univox, a shade finer grit perhaps. but damn close for no money. and for that reason handy for practise occasions when i don't want to take best stuff. lost, broken, stolen, etc.

as the layout borrows heavily from the classic univox (shin ei, unicord, etc) superfuzz, i wondered how easy (or not) it would be to apply a few of the basic univox superfuzz mods (octave trim, diode trim, swapping diodes out, etc) to it, to see what it can do when pampered. it is a truth universally acknowledged that cheap dates are invariably more responsive to pampering than their upmarket equivalents (younger readers take note).

as it’s supposed to be a clone of the boss fz-2 hyperfuzz (how faithful i’m not entirely sure) i checked out the threads here…
http://www.freestompboxes.org/viewtopic.php?f=11&t=868
http://www.freestompboxes.org/viewtopic.php?f=1&t=10954

…and read that gila-crisis (member here) has successfully applied the superfuzz mods to the boss.
though as the detail (pcb, schematic) refers to the fz-2 specifically, beyond establishing that the mods are feasible, and clarifying what and how needs to be done to effect them, i got stuck trying to trace the sf300 pcb according to the fz-2 schematic.

anyway, i did a quick photoshop thing that pinpoints the bits of the fz-2 schematic i’m trying to find on the sf300 pcb.

extract from boss fz-2 schematic.bmp

and another of a univoz superfuzz schematic (mods added by derringer here, thank you) showing what i want to do when i find them.

extract from univox superfuzz schematic (w derringer mods).bmp

full fz-2 schematic here: http://personal.inet.fi/koti/holmberg/images/hyper.jpg

i took my sf300 to bits and took the best photos i could of the board.

behringer sf300 pcb back top half jpg.jpg

behringer sf300 pcb back lower half jpg.jpg

behringer sf300 pcb front top half jpg.jpg

i’m stuck at trying to trace the pcb (numbers and values on fz-2 schematic may not mirror those on the sf300, though it is supposed to be a clone).
basically i’m looking for the octave pair and the clipping diodes. to begin with.
instinct makes me think (on the sf300 pcb back lower half photo) diodes d4 and d5 look a decent bet. especially as t13 (just above) leads into a 27k and 100k resistor (which corresponds with t13/q13 on the fz-2 schematic). but where’s the other tranny if that’s half an octave pair? doesn’t follow.
anyway, getting a bit boring (frustrating, i’ll be honest) so am putting it away for the night. but if anyone else wants to play with it they are more than welcome.

but i thought it would be a good idea to post all the links and notes i’ve gathered (to get the idea straight in my head) as it may inspire someone wiser than i, who is interested in doing the mods, to pick up the baton and run with it.

i think the sf300 has untapped potential, being so close to a univox superfuzz and so cheap. yet there is nothing out in the webs specific to modding this pedal, this way or any other.

it struck me as something worth considering anyway.

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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby tube-exorcist » 02 Sep 2014, 20:22

T4 and T5 is the octave pair, R9 is the collector resistor, R10 is the emitter resistor, R16 and R18 are the resistors from the phase splitter to the octave pair and T6 is the phase splitter transistor.
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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby tabbycat » 03 Sep 2014, 23:34

tube-exorcist wrote:T4 and T5 is the octave pair, R9 is the collector resistor, R10 is the emitter resistor, R16 and R18 are the resistors from the phase splitter to the octave pair and T6 is the phase splitter transistor.

many thanks for the tips, tube-exorcist. much appreciated. i'm totally confused by this layout. screening on blue laquer with tracks semi-visible underneath and electrolytics on the other side is like the dance of the seven veils. schematics and vero layouts i can follow with patience but this is something else.

with this sort of thing do you forget about trying to trace and just look for tell-tale clues to find specific bits? 'signature' features of common groupings?
the emittor resistor is shown as a 2k9 on the fz-2 schematic, but is given as a 1k8 here (sf300).

have labelled the layout according to your comment.

sf300 named bits.jpg


did i guess right about d4 and d5 being the clipping diodes (despite being miles away in board geography terms)?
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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby tabbycat » 05 Sep 2014, 23:57

if any wise and worldly stomper out there wants to have a educated guess at which are the octave diodes i would be grateful for the confirmation.

my guess is d4 and d5 (back of sf300 pcb, lower left half) but calling it a guess is a bit misleading. lucky dip is closest to the truth. needs a professional eye.

in the meantime have gleaned (torch and magnifying glass) electro-cap values. will do a fancy turn and translate these to the back of the pcb over the relevant solder points, but this will do for now.

sf300 pcb electrocap values jpg.jpg
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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby tube-exorcist » 06 Sep 2014, 00:51

If you are looking for the clipping diodes then they are D2 and D3 (near/below the fuzz switch).
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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby tabbycat » 09 Sep 2014, 01:42

tube-exorcist wrote:If you are looking for the clipping diodes then they are D2 and D3 (near/below the fuzz switch).

many thanks for bailing me out again tube-exorcist. much appreciated. am clearly 'tangibly shit' at making sense of printed pcbs like this. not like schematics or vero layouts. this stuff is inscrutable and patently beyond my current level of competence.
"But I tried, didn't I? Goddamnit, at least I did that..."

anyway, thanks to a much-esteemed contributor, i at least know where i now need to focus my efforts. shall see what i can do.
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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby Greenmachine » 09 Sep 2014, 04:37

Lots of electrolytics on that board
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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby tabbycat » 09 Sep 2014, 23:47

Greenmachine wrote:Lots of electrolytics on that board

is that intended as a cryptic clue to decrypting this beast?
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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby Greenmachine » 10 Sep 2014, 03:37

tabbycat wrote:
Greenmachine wrote:Lots of electrolytics on that board

is that intended as a cryptic clue to decrypting this beast?


Ha! No ... Sorry. Just an observation.
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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby tabbycat » 11 Sep 2014, 22:37

Greenmachine wrote:
tabbycat wrote:
Greenmachine wrote:Lots of electrolytics on that board

is that intended as a cryptic clue to decrypting this beast?


Ha! No ... Sorry. Just an observation.


across.
1. obscene and not heard. eleven letters. begins with 'o' and ends in 'n'.

it certainly is nearing max-cap population density. have you tried one of these? very tasy little beastie. pocket rocket.
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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby tabbycat » 16 Sep 2014, 22:45

'here's the thing...' as tarantino would say...

i am planning to:
swap out the clipping diodes to a dpdt switch (with a couple of interesting contrasting series pairs of silicon diodes, or a pair of silicon diodes and a pair of leds). then take the ground from that pair to a 10k trimmer (or maybe even a 10k pot if it does enough) before sending to ground points on the board where original diodes would have grounded.

this pic shows the wiring.

sf300 clipping diodes closeup jpg small.jpg

i have a couple of questions, if anyone is up for considering this.

a. do i have to take the ground from the trimmer to both the original diode grounding points (do i need the green illustrated ground, or will the pink one do the job of both, ground being ground).

b. do i actually need to remove the original diodes? or will what i'm doing (with the pink illustration) effectively bypass them and their function anyway. if what i do makes the pedal sound worse, then it would save me having to solder them back in if i ever want to restore the pedal to the stock pair.

many thanks to anyone who is able to clarify that for me. have done as much research as i can into what i'm trying to do, but feeling a shade insecure about my ideas. i know what i'm trying to do but not if this is the best way to achieve it.

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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby DrNomis » 18 Sep 2014, 04:32

tabbycat wrote:'here's the thing...' as tarantino would say...

i am planning to:
swap out the clipping diodes to a dpdt switch (with a couple of interesting contrasting series pairs of silicon diodes, or a pair of silicon diodes and a pair of leds). then take the ground from that pair to a 10k trimmer (or maybe even a 10k pot if it does enough) before sending to ground points on the board where original diodes would have grounded.

this pic shows the wiring.

sf300 clipping diodes closeup jpg small.jpg

i have a couple of questions, if anyone is up for considering this.

a. do i have to take the ground from the trimmer to both the original diode grounding points (do i need the green illustrated ground, or will the pink one do the job of both, ground being ground).

b. do i actually need to remove the original diodes? or will what i'm doing (with the pink illustration) effectively bypass them and their function anyway. if what i do makes the pedal sound worse, then it would save me having to solder them back in if i ever want to restore the pedal to the stock pair.

many thanks to anyone who is able to clarify that for me. have done as much research as i can into what i'm trying to do, but feeling a shade insecure about my ideas. i know what i'm trying to do but not if this is the best way to achieve it.

tabby.



What you could try doing is use a multimeter to check which of the solder-pads for the two diodes is connected to circuit-ground, with regards to desoldering the two original diodes, you might have to desolder them in order for your intended mods to work correctly..... :thumbsup
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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby tabbycat » 18 Sep 2014, 21:41

DrNomis wrote:What you could try doing is use a multimeter to check which of the solder-pads for the two diodes is connected to circuit-ground, with regards to desoldering the two original diodes, you might have to desolder them in order for your intended mods to work correctly..... :thumbsup


many thanks for your help dr nomis. will do exactly that.
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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby tabbycat » 03 Nov 2014, 03:13

finally got around to playing diodes with this today.

it’s a killer fuzz anyway but i felt there might be room to push it further into univox superfuzz (6 transistor, not fy2 companion) territory with a couple of well-placed mods. as standard, it’s a slightly finer grit with more sustain than the as-close-as superfuzz clone i have built and all of those i’ve heard in the decent youtube demos. gearmandude (he of the white coily cable) does a good one of the univox i think.

i thought the diodes would be a good place to start as the univox’s seem to sound best to me with germanium diodes. my clone (mike livesley layout) uses a pair of oa-91s with sometimes 2n3904 and sometimes 2n2222 transistors. i socketed them when i built so can switch when i feel like a change, dark and bright. i have heard much talk (from people who i think know what they are talking about) who say the 2n2222 are closest to the original 2sc828q (now obsolete and not so easy to find).
anyway, re diodes, i think the sf300 (a supposed clone of the boss fz2 hyperfuzz) takes silicon transistors. the fz2 does (according to schematic i posted above).

as i experimented the diodes that came closest in tone to the standard sf300 (i have one unmodded so i could do a direct side-by-side comparison) were the 4001. they had a more compressed, finer grit, feel compared to the silicon 4148 i tried. i actually preferred the more course 4148. more on that in results.
these are the diodes i tried and my subjective opinions about them (not objective factual information). i am a person not an oscilloscope, but i think i have a good ear for tone.

1n60 germanium (clipping pair).
fine grit fuzz well spread from bass to treble. relatively dark sounding, quietest of all i tried (needed most volume). got some nice throbbing waves in the decay around the twelfth fret. good combination of texture and darkness. but definitely better than standard if you are looking for univox textures.

1n34a germanium (clipping pair).
fine-to-medium grit fuzz well spread from bass to treble. raspier, more overtones (octave broke through more) and bit more attack than the 1n60. also more impressive initial ‘blast’ and longer sustain than 1n60. not as dark as the 1n60. these gave most authentic sounding univox tone. pretty much nailed it. the wide uncompressed chaotic expansiveness of the univox all there. perhaps not as chaotic and blistering as the original, but as good as you are going to get for pocket money unless you are going to build a univox clone or stump up a few hundred pounds for an original (and hope you get a good one, as quality varied over the years). sexy tone.

4148 silicon (clipping pair).
more explosive and crunchy attack compared to the germaniums. the raspiest and harshest the bunch, in a good jamc way. the gain control was rendered fairly useless using these as the tone was relatively blistered-out across the dial. winding back the guitar volume just gave an ugly gatey mess. despite the harshness the tonal range was pretty full, bass to treble. the brightest sounding of all i tried.

4001 silicon (clipping pair).
when i first heard the 4148 i thought they were the standard sf300 ones, but when i tried these i decided they were actually closer due to the slightly finer grit and more compressed tonal range. maybe the standard ones are actually between the two. these were initially harsher and more punchy than the germaniums but without the darkness or the grittiness. the tone was very tight and tense. they definitely seemed to be pressing in on the tonal range more than any of the others i tried. sustain was forever, giving the octave time to swell, perhaps as a result of the compression.

red ‘bright’ led (clipping pair).
threw these in as i had some and have never heard (or seen, they glow and pulse like valves) led clipping. these seemed to clip least. were closest to no diodes at all. i couldn’t decide if i liked the ragged loose harmonics all over the place feel these had, or was just drawn to the novelty. but definitely different to all the other options i tried. a lot of chaos allowed to hang out with these. throbbing pulsing harmonics and lots of octave. loud too. had to turn up from germanium to silicon and then right back down with these. interesting.

was thinking about putting everything apart from the 4001 (as i have an unmodded which covers that better) on a 3 pole 4 position switch, because they all have their merits and particular character. but that would mean a rehouse.
as it is am going to opt for the 4148 pair and the 1n34a pair on a sub-minature dpdt switch and try to squeeze it into the existing housing. these two pairs captured the most characteristic qualities of the germanium and silicon options, so nail all that is best about both worlds. the 1n34a nails the univox, as-good-as-damn-it for a pocket money clone. and the silicon gives a brighter crisper option of that to cut through should the 1n34s ever consider getting lost in the mix.

reference pics.

DSCF0836.JPG

top one shows the pcb of the sf300 with standard diodes removed. the white wire goes to the diodes to be tested and the black wire comes back from the diodes to be grounded (circuit ground).

DSCF0834.JPG

bottom one shows my testing set up and the diodes i played with.

other things.

i did try using a 10k pot as a diode-to-ground trimmer, but as its functionality is to ‘take away, not add’ (and this isn’t a pedal suited to subtlety) things only seemed to get less interesting as i rolled the intensity off.
am going to turn my attention to fitting an octave trimmer next, but that does it for diodes with this one. am happy with the results. when i get it boxed up again i may do a head-to-head with my unmodded sf300 and my univox clone and post it in soundcloud so you can hear the difference and similarities for yourself.

having spent a lot of time and energy experimenting with this, and having a good univox clone to compare it to, i think it gets pretty damn close for no money. and certainly, compared to the trauma and time-spent on building another univox clone, this diode swap mod is a total walk in the park.

many thanks to those contributing fsb members above who helped get to the point where i could do actually do this diode ‘play–off’. it has been my first original mod (haven’t seen it posted anywhere else) so was working from nothing with just a rough idea about what i wanted to achieve.
although it’s not much of a mod so far (just some experimentation and a diode swap essentially) it has been quite empowering in an freestompboxes way. thanks chaps.

photos of finished diode mod and experiments with octave trimming to follow.

tabbycat.
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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby tabbycat » 03 Nov 2014, 05:40

to add some objective readings to my subjective ideas, i have just learned how to read diode values using a dmm.

here are some voltages for the diodes i used, lowest value to highest.

0.276v = 1n60p (germanium)
0.338v = 1n34a (germanium)
0.566v = 4001 (silicon)
0.588v = original sf300 diode (unknown silicon).
0.619v = 4148 (silicon)

quite pleased that voltages seem to back up my impressions.

if anyone knows exactly what the standard sf300 diodes are (can see them in photos above) i would be grateful for the information.
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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby tabbycat » 25 Nov 2014, 17:36

DSCF0843.JPG

removed both clipping diodes (D2 and D3) and soldered wires to the top and bottom solder points for D2 (white = positive, black = ground)

DSCF0839.JPG

drilled hole for switch (subminature dpdt on/on). had to think carefully about position of diodes as it is a seriously tight fit.

sf300 diode mod.JPG

used a pair of 1n4148 silicon diodes and a pair of 1n34a germanium diodes. this gives me a bright raspy option and a dark smouldering option.

DSCF0879.JPG

a cheap pocket rocket (cost £15) based on the univox superfuzz with silicon and germanium diode switch.

sounds stupendous.

many thanks indeed to all who offered help and suggestions. doesn't look much but has been my first original mod so important to me. first step.

thinking about adding an octave trim pot next but as space is so limited it would require a rehouse. will think about.

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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby astrobass » 27 Nov 2014, 02:49

The 1N60 diodes I have measure around 0.500 V, the last one I checked was 0.506. Are you sure those aren't 1N270? They both use the same large glass tubes.

Sweet mod though.
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Re: pimp behringer sf300 superfuzz with univox superfuzz mod

Postby electrip » 27 Nov 2014, 05:04

All Vf_diode should be measured and listed with given current.

0,5V could be Schottky-Fake-Germanium 1N60.

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