Mosrite - Fuzzrite  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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Post by Barcode »

For anyone interested, here is a PCB layout I made up while bored at work. It's for the negative ground Si version. It is loosely based on IvIark's tagboard layout, but with spacing for PCB mounted pots, and with the component values changed slightly to match more standard values.
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Mosrite Fuzzrite, NPN Neg ground
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Post by Thaxt »

My Fuzzrite might be one of the later-on runs, as it has 2 black, cylindrical plastic knobs (w silver tops) instead of the domed metal derby hat types the originals have. Did'nt production trail off sometime in the early 1970s? Art Thompson's book (The Art of the Stompbox) reads out this way.

The board is gooped w a light beige, aging, cracking material (epoxy?) , but I was able to tilt back one trannie & see the distinct #: MMPS3710. The data sheets indicate they are low-mid gain NPNs, seem similiar to 2N3904s or 2N222As. Pots are 300K (Fuzz) & 250K (Vol) respectively. I have to do a bit of goop notching here & there to see if that 22K resistor is in there - I count 4 so far, but, the goop around one trannie is thick.

Most of the DEPTH controls' sweep is very inadequate, soundwise - only at full volume, & hitting the last 10' maxed CW of the Depth pot does it give any decent kind of Fuzzrite genre sounds. Definitely a highpass spatterfuzz that way. It does have a good, compressed sustain. I needed to put lots of bass & mid EQ on my mixer to get it to be more effective. Honestly, I like my various Gus Smalley Ritefuzz mods & the Greenbomb better.

Doesn't look like a true bypass switch wiring by any stretch of the imagination..I wonder to what extent this interferes w the sound?

It IS good for some dark, mysterioso/compressed/lowpass sounding lead guitar , using my SG Standard's bass p'up, w the Depth control anywhere down from full on CW. Might be cool to record that texture of lead guitar on some things, as it isn't harsh....interesting & weird intermod sounds w 2 string doublestops....some odd overtones live there. I can see it having value on a lead piece that would ask for that sound....it's dark, self compressing, & a bit droning. Something right out of a lesser known psych band's 1967-68 LP. Yeah, dark psych leads might benefit from it.

I'm mulling over its rarity, (& ebay) prior to just stashing the guts away (intact in a plastic box) & building one of the more updated, enhanced mods into that genuinely great steel box. The graphics are in pretty good shape, btw.

Another case of having a genuine Model T in my driveway. It's not going to do anything spectacular, of course, but, there is that sentimental pull w anything like this, plus the "I might need this one.." factor. Not sure if I want to f**k w it, good case & dud sound notwithstanding.

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Post by Electron Tornado »

If you've got an example of a real rare and vintage pedal, I'd keep it together so it will hold its value. If you want to build a Fuzzrite clone, there are places where you can find similar, sloping enclosures.
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Post by Mr. Bill »

Photos of the guts would help out. If the pedal is not what you want, sell it and buy or build something more to your liking. I'm not one for ruining a good original pedal that I'm sure someone would want to have. Just my two cents.

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Post by phibes »

+1 on leaving it be. If it's an original somebody will pay good cash for it. You can make a better one yourself for way cheap and buy a fridge full of beer from the profits of the original.
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Post by Thaxt »

Thanks for all your feedback.

Anyone who is doing some mods or clones might try out the MPS/2N3710s. They are said to be a pretty direct sub for TZ82s & the NTE85s. 2N3904s are very good, & using 2N5059s can yield a real buzzbomb of a clone for many fuzzes, including these. I have tried them on Fuzzrite clones, & they do just that.

btw: Just where can I get one lof those similiar strong-steel type enclosures? Most of what's out there is aluminum (EZ to drill, fer sure)

Pedalenclosues has nice ones, Good powder coated aesthetics from pedlapartsplus as well. Steve Daniels has been a great source of things since the early 2000's. Were you talking about a Mosrite or Big Muff quality of steel, ready to use enclosure? I would like to add any such site to my list of links. That Mahony Mosrite box looks really slick.

No pix of my Fuzzrite right this min, but, I will keep it intact. It does need a change of battery clip, no prob; those unusually thin wires have broken off the on/off switch easily, all this without much opening up of the unit. Also, the black wire which runs from the lug 2 of the Depth pot to the Output pot has frayed strand ends, which have broken twice. Of course I'll replace this (short) wire w a better one - I don't think that would constitute much of a fault to an ebay buyer who is looking primarily for an intact circuit & sound, & well preserved graphics.

Those plastic knobs are an anomaly for Fuzzrites; all of the FRs I had ever seen, w 'out exception, had the normal metal, 'derby hat' knobs. I think these black plastics are original knobs on this box, as they push-fit perfectly on the plastic pot shafts. I wonder if this FR really is from a later, last call production run. The pots, btw, have 'Made in Mexico' stamped onto them.

I haven't disturbed the board to any signifcant extent, & certainly, all circuitry is completely original & unmodified in itself. The previous owner had resoldered the + battery lead to the board, chipping away a small circle of goop in the immediate area - it must have broken loose. It was that way when I got it.

I'll recheck ebay & see what's doing, tho, I always do tend to keep them.

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Post by Mr. Bill »

Mosrite also had a line of amplifiers that originally used the derby knobs, that were later changed to black knobs with silver caps. The knobs that you are describing sound like these same style knobs. If you search for pictures of the amps you can compare them.

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Post by Thaxt »

The problem w my vintage Fuzzrite seems to have 'solved' itself...as I worked with its insides, (even w caution & care) several wires broke off, right @ the wire/goop surface junction. It's a Sanner Si model, I can see by the resistor shapes , # s & placements. Not worth an ebay foray, @ least to me. I don't think I really wanted to part w it anyway. My solution is to build one of new versions into the original case, sort of surprise the curious.

I'm gravitating to the Ge schematic, but using Silicon trannies. I've tried the BC109 for Q1 into a BC108 Q2 setup (too much HUMMMM!). A 2N2907 into a 2N3906 - same thing: hums like crazy @ full treble-buzz. Just this eve, I've gone back to my breadboard & subbed a 2N5133 Q1 into a SE4010 for Q2 - still, that ever-obnoxious (((hum))) when both VOL & DEPTH are up full.

The Ge schematic version, especially when I carefully roll off the Vol control on my SG ( using my ears ) sounds closest so far to the Buffalo Springfield recordings I'm trying to emulate ; it really does sound like Steve Still's 'Bluebird' riffs, 'Mr Soul' etc.

The problem is that damned hum - I guess this is inherent to this particular animal. Anyway, I'm now going to try a 2N4401 as Q1- a bit more gain than the 2N5133 - but also: some fine-tweaking of the biasing resistors. I want to go for a really optimized Fuzzrite. I tried placing a 50K pot between the +9V & the collector of Q1, then decreasing the pot's value downward until the hum reduced. This does, however, alter & dilute the characteristic, sustained raspiness/nastiness that is the Fuzzrite's specialty.

A lot of my Fuzzrite modding (since the Smalley Ritefuzz) has involved making those 2 outcaps bigger, going upward from the .0022 to as far as .022, sometimes. You DO gain bass w the .0068uf mod, f'rinstance, but @ the expense of those (((zzzizzz ing))) bumblebees. This is a pedal who's original versions might sometimes best be left intact & used w, say, plenty of 80-100HZ EQ. Sounds great this way my Yamaha mixer. Plenty of albums were (or are) recorded tweaking these late 60s types of fuzz sounds in just that way....running into fully cranked amps, miked & then compressed, etc, etc. You get the bumblebees across without excess (or limited?) sting.

The Green Bomb carries outcap enlarging all the way up to .047s going out, but I wanted a simple, 2-knob fuzz to put in the original case. The Tin Lizzie's VGC frame gets a more modern engine. I suppose I could use a 50K trimpot as an internal GreenBomb SHAPE control. Having an original FR case to work with here, I especially want to make this mod sound downright opto-cool.

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Post by monkeyxx »

I was thinking about the catalinbread merkin, then I thought, "what the hell...why don't I just go full retard and build the dang fuzzrite" then I found out there were two, so I built them both. I used IvIark's nice layouts, I particularly like the tag board silicon one, it's pretty when built. the Ge one is not on the David Main prettiness plane but it is a good layout, they both worked without a hitch. I did the parallel resistor trick to get my 350K pots (1.2 Megaohm resistor across lugs 1 and 3 of a 500K pot)

The silicon one is what I was expecting from what I'd heard in the past of these things, really wild and noisy. If you hit a chord at full volume it's a train wreck of sound. If you back the guitar volume off just a bit, and turn the mix more toward the bassy side of the pedal...it's a really nice "rock out" kind of garagey metal punk whatever tone that's good for riffing. I like it. It gets nasty, that's what I wanted, I was tired of pretty sounding fuzzes for just a moment, and have a lot of them. It's not terribly far removed from a MK II Tonebender sound. This one's really noisy so you'll probably want shielded in and out wires within the pedal. I used 2N222A metal can transistors

The Ge one surprised me, there is a sweetness to the tone, even though it's funky and wooly mammothy, sort of pinched and gated and all that. The character of the distortion is very pleasant. Yeah it's "warm" and "organic" and all that crap. But still crazy.

I tried the 200 and 50 hFE combo somebody mentioned, but it just wasnt "rite." The fuzz was too splatty and weird on the bright side, and the dark side was too clean. I tried somebody else's 80-100ish for both recommendation and that turned out "Mos excellent." I used 2N404 transistors

This Ge circuit has trouble getting loud at low amp volumes, but, I suspect in daytime hours when I get to crank up the amp, it will probably be a respectable output, since I usually like a louder clean tone and a slightly quieter distortion in that scenario. I guess that's just how this circuit works, you'd have to add a boost stage of some sort like somebody else mentioned to get ample output from this, I suppose.

Anyway I'm very pleased with the two, and expect that each will get some use. I was inspired to play by the sound of them. In sound clips they sound ridiculous, but when you've got one under your fingers, it's a different story altogether! :block:

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Post by monkeyxx »

forgot--the silicon version has more than enough output, gets well past unity gain

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Post by monkeyxx »

110 hFE seems to be a sweet spot for Q1 gain in the Ge version. 100 was a little too clean and 120 a bit overcompressed, to me. sounding quite nice, today. Yes, at moderate volume there is an urge to slightly turn down the effect volume due to the brightness of it, so it's plenty loud, just an unusual tone that doesn't sound "full." makes me think of Moog gear or video game music, stuff like that, kind of organic and comical at the same time

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Post by RnFR »

for the low output, you can raise the value of the volume pot. this will bring a bit of low end back in as well.
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Post by monkeyxx »

I did a switch to bring both output caps up to 6.9 nanofarads and I'm getting a lot of mileage out of that. the nasty treble content is still there, but it's balanced out a bit by a lot more low end coming through. I'm thinking some AC128 might even further smooth things out, or some GT309E

I swapped in a 1M volume pot at the same time and it sounds fine too I didn't compare directly to the 500K though, need to do that

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Post by Thaxt »

I just ran into vids of Iron Butterfly's "Most Anything That You Want" on YouTube...(followed up by a quickie relisten to some of 'Inna Gadda Da Vida'). Some nice leads in the first song. The Fuzzrite is sonorous there, & very sustained. I think more than the usual models. It's a better example of Iron Butterfly lead sounds than IGDV, IMO. Also: There is "Time of Our Lives" for a similiar sound.

Most of the Fuzzrite Q&A lore on the net says that Erik Brann used Mosrites on the Butterfly cuts, but one speculation pointed confidantly to his using the early Ge version - while another broached the possibility of that on-board (Mosrite) built-in-amp circuit being used.

I do hear much more melodic sustain (& bass) w this song's fuzz...wonder if Erik was cascading 2 of them? Not an unknown trick in those days.

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Post by Chugs »

Erik was probably running into an amp that was breaking up slightly. That would increase the sustain.

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Post by DrNomis »

I wonder if Robbie Krieger (spelling?), the Doors guitarist, used one of these for the lead break on the studio recording of the song "When The Music's Over"?.... :hmmm:
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Post by fuzzheimer »

DrNomis wrote:I wonder if Robbie Krieger (spelling?), the Doors guitarist, used one of these for the lead break on the studio recording of the song "When The Music's Over"?.... :hmmm:
I hear what you mean but I can't confirm or deny. He was generally known to use one of the Maestro FZ fuzzes.

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Post by monkeyxx »

ok here's my final answer. 100 hFE is the magic number for Q1. any higher (110 even) and you get into special effect splatty farty type sounds. they are comical and wonderful but not generally useful for regular playing. 100 hFE sounds like the DAM Fuzzrong clips on youtube, which I'm using as a reference of a well-tuned circuit. 90-100 is probably a good range to look for. Now the pedal makes sounds I can actually get behind and feel, it's a lot more open sounding. I also notice a slight octave sometimes on lead playing, which is lovely always to find. I think 80 and lower should be a good range for Q2. The "fat" switch (adding in the larger caps) makes a nice woman tone for neck pickup soloing vs the regular thin-ish tone.

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Post by Chris Brown »

Here's a perf layout I did for the GE fuzzrite... I had a scrap of perf this size but couldn't find a layout to fit it so I threw this together. Most of the layouts around the web are for the si version with the 470Ks. This layout is from the Japan schematic.

I haven't built it yet so it's unverified but I've been over it a few times and it looks right.

I'll probably use and axial for C6 so I'll have to move C1 down but it's not worth changing in the layout... anyway, have fun and enjoy!

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Post by Chris Brown »

Chris Brown wrote:Here's a perf layout I did for the GE fuzzrite... I had a scrap of perf this size but couldn't find a layout to fit it so I threw this together. Most of the layouts around the web are for the si version with the 470Ks. This layout is from the Japan schematic.

I haven't built it yet so it's unverified but I've been over it a few times and it looks right.

I'll probably use and axial for C6 so I'll have to move C1 down but it's not worth changing in the layout... anyway, have fun and enjoy!

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verified :D

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