Mosrite - Fuzzrite  [schematic]

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

I build IvIark's Tag layout and it was a pretty cool :D

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Post by RnFR »

might as well post a link to this guy for those interested.

http://apocalypseaudio.blogspot.com/201 ... -fuzz.html

and also- i have had excellent results lowering the output cap on the first stage, while keeping the larger one on the second. with .0033 on the first, and .047 on the second, there is a nice smooth increase in the gain control that original doesn't have. whether or not this is more or less desirable is of course up to you.
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Post by Thaxt »

RnFR: Thanx - I'm definitely going to try that change, on the 1st outcap. Also vary this, etc.

:idea: Try padding the resistors on each side of the 'fuzz' control to the outcaps on the Sanner Si version.

I.E., place a 22K-33K resistor in series on each side of the 2 (outer) leads from the 100K/B pot to those outcaps from Q1 & Q2. The middle lead still goes to the 100K/A output pot, as usual. This seems to change the tonesweep, a bit more optimal. I use 22Ks so far. A tweakoff point , so to speak.

Somewhere in the 1990's, a lot of bands (Sonic Youth being one) started raiding the back shelves & dump-lots of music stores, digging up all those
Fuzzrite, Foxx Tone Machine, Shin-Ei, Univox Superfuzz octabuzz screechers, the better to get some kind of unique sound, to stand out in the ocean of bands/sounds out there.

A lot of early Indie bands should have just soldered in .0033uf or .0047 output caps on anything they were using, that would have got them into the general zone, initially.

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Post by neoflox »

Hi everyone,
I build the classic Fuzzrite based on the fuzzcentral.com schematics and it sounds freaky good except one little issue – only with volume max'd I get unity volume with the clean signal. Is this supposed to be normal? If so - is there a workaround for more output volume?
Appreciate any hints.

Cheers :block:

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Post by keto »

No, that's not right. I build mine and a couple for friends from their layout (which I have to assume is the same as the schematic, didnt check) and they have HUGE output, ie., unity is about a quarter turn up. Check transistor orientation maybe?

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Post by neoflox »

keto wrote:No, that's not right. I build mine and a couple for friends from their layout (which I have to assume is the same as the schematic, didnt check) and they have HUGE output, ie., unity is about a quarter turn up. Check transistor orientation maybe?
Damn. You know that is not the answer I wished to get. :whappen:

Would someone then be so nice to have a look at this layout? The top one is the classic fuzzrite, (based on the appended schematic) I build recently. The transistors are right the way they are (used 2N3904) so it's got something to do with the layout. Pots are 500k for Depth (attack/fuzz) and 50k for volume. As I said, it is the original raspy sound but only equally loud compared to the clean signal when Volume is max'd. Oh and nevermind the bottom, larger layout. It is my take on the green bomb schematic but it is faulty …

Thanks in advance! :horsey:
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Post by orpheumlover »

I'm thinking of building a Ge version of this. What would be a good Ge substitution for the 2N3904? Would it be 2N408, NKT318, or 2N2613?
Thanks!

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Post by theehman »

orpheumlover wrote:I'm thinking of building a Ge version of this. What would be a good Ge substitution for the 2N3904? Would it be 2N408, NKT318, or 2N2613?
Thanks!
There's a completely different schematic for the earlier Ge version. It uses a 2N2613 and an 2N408.
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Post by orpheumlover »

Thanks for letting me know about the different schematic for the Ge version. But, since this is a Mosrite Fuzzrite thread, and I hate to ask because you guys may flog me because of the consequences, can anyone post the Ge version of the Mosrite Fuzzrite? I know, I know, it's probably availablbe somewhere out there on the web...but, since this is a Mosrite Fuzzrite thread...let's keep all versions together. (Let the floggings begin!)

Thanks again!!

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Post by theehman »

orpheumlover wrote:Thanks for letting me know about the different schematic for the Ge version. But, since this is a Mosrite Fuzzrite thread, and I hate to ask because you guys may flog me because of the consequences, can anyone post the Ge version of the Mosrite Fuzzrite? I know, I know, it's probably availablbe somewhere out there on the web...but, since this is a Mosrite Fuzzrite thread...let's keep all versions together. (Let the floggings begin!)

Thanks again!!
ge_fuzzrite.gif
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Post by RnFR »

here's a link to some docs for a mosrite amp that contained a built in fuzzrite. they were kindly donated by an anonymous individual. thanks again!
viewtopic.php?f=2&t=9606


here is the schem for the onboard fuzzrite board, it looks a bit different than the fuzzrite we know-
Mosrite Amp - FuzzRite Schematic
Mosrite Amp - FuzzRite Schematic
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Mosrite Amp - FuzzRite Board Parts 1
Mosrite Amp - FuzzRite Board Parts 1
Fuzzrite amp parts1.jpg (139.39 KiB) Viewed 37619 times
Mosrite Amp - FuzzRite Board Parts 2
Mosrite Amp - FuzzRite Board Parts 2
Fuzzrite amp parts2.jpg (65.3 KiB) Viewed 37619 times
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Post by orpheumlover »

Holy crap that was fast!! Thanks so much...you are the BEST (no matter what anyone else says!) (a bad Rodney Dangerfield joke circa 1980, sorry)! Now I can get to work and throw one together.

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Post by Dan N »

Cool!

Of course, 4 batteries will take up a lot of space in your enclosure. :roll:
Dick joke has expired.

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Post by RnFR »

well, you could just calculate the voltage drop for that 47K resistor from 33V...
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Post by neoflox »

neoflox wrote:
keto wrote:No, that's not right. I build mine and a couple for friends from their layout (which I have to assume is the same as the schematic, didnt check) and they have HUGE output, ie., unity is about a quarter turn up. Check transistor orientation maybe?
Damn. You know that is not the answer I wished to get. :whappen:

Would someone then be so nice to have a look at this layout? The top one is the classic fuzzrite, (based on the appended schematic) I build recently. The transistors are right the way they are (used 2N3904) so it's got something to do with the layout. Pots are 500k for Depth (attack/fuzz) and 50k for volume. As I said, it is the original raspy sound but only equally loud compared to the clean signal when Volume is max'd. Oh and nevermind the bottom, larger layout. It is my take on the green bomb schematic but it is faulty …

Thanks in advance! :horsey:

Nevermind, seems to have been an impendance issue in my amp rig. My layout is hereby veryfied :horsey: I'll maybe add a filter cap and polarity protection later, but enjoy that compact layout. 1590A? :secret:

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Post by Thaxt »

With the Ge Fuzzrite schematic, try setting the initial gain resistor to a lower value - say, 470K - 1M. Then, use a 500K/L pot as a gain pot, between the base & collector of Q2. Putting pots in these positions (as gain resistors) can produce more hum, but, the 22K resistor connected on the output line will take some of this out.

That 10M gain resistor on Q1 yields one ton of gain...I even changed this part downward to a 4.7M, then a 2.2M fixed resistor, but, the whole thing still can hum a lot if/when you start tweaking the output cap values larger - to .022, or even .047 as I've used, & like to do. 1M here seems good for now.

Wire (better still, breadboard) the output cap from the collector of Q1 directly to the base of Q2. Ditch the 350K/250K/500K pot that pans between the 2 outcaps. (You can always vary this change later on for different FX,or return to the original setup) Then, take the output directly from the (.022/.047/ even .0068) outcap off the collector of Q2, & make this a direct output to a 500K pot.

In short, you are no longer panning between 2 outcaps at this point. Everything comes off the Q2 one, to a 500K output pot.

Sometimes, I think the result might require a Noise Gate pedal (or any Noise Gate), but, the resultant sizzlerasp/thickbuzz that happens when you turn the 500K gain pot towards max is worth the ride. Gives some really super-sustained, Fuzzrite timbre sounds. This thing can really hang on for great sustain, & trailoffs. A bit of crackle in there, too, @ max gain. The overtones do get more charactersitic when you reach the latter sweep of this 500K gain pot - the thing gets really think & raspy (for me, anyway) Lower this gain pot - even cutting back on yr Vol control - & you can get a very different timbre, cleaner sounds. A very versatile experimenter's mod. this one.

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Post by Thaxt »

Looking @ the onboard amp Fuzzrite, I first thought of taking out the 47K voltage resistor, to set it up as the typical +9V ciircuit most builders work with.

One might then try 2N3904s or 2N5088s as experimental transistor subs (the usual). 2N2926s show up on the onboard fuzz in the Acoustic 360 amp schematic. Are they meant to be used w higher voltages?

Taking from my other Fuzzrite modding around, I'm looking at the 1M gain resistors on both trannies, as points to start modding this circuit. I've been using dual-gang pots a lot in the past year's mods, mostly for tuneable, passive tone circuits, but found they can also be useful as gain controls. Maybe a 1M/L, dual-gang pot would be interesting to use on this circuit, to sub for gain resistors on both Q1 & 2. Or, a 470K fixed resistor in series w a dual-gang 500K/L pot. That can give you an idea of what one might like to use if you put equal value, fixed resistors there.

Or: I'd try putting a 500K/L to 1M/L pots (separate ones this time) in both gain resistor spots, & tune both by ear. As w the Ge Fuzzrite circuit, I might end up making the gain resistor of Q2 the determinant spot for fuzz intensity & timbre. This works on my (silicon-ized) Ge Fuzzrite mods.

Putting pot leads directly onto the B/C junction of transistors does tend to pick up much more hum. But, you get great fuzz gain changing controls w these. Maybe some of this is due to the breadboard's tendency to pick up more interference sounds. I'd like to eliminate this hum from a built pedal. The 100uf cap add-ons don't seem to cut this problem, nor the other AMZ hum cutting mod of putting a 100-330 ohm resistor in series w the +9V power supply. I usually use 9V batteries on the breadboard, rather than an adapter.

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Post by Solidhex »

Thaxt wrote:With the Ge Fuzzrite schematic, try setting the initial gain resistor to a lower value - say, 470K - 1M. Then, use a 500K/L pot as a gain pot, between the base & collector of Q2. Putting pots in these positions (as gain resistors) can produce more hum, but, the 22K resistor connected on the output line will take some of this out.

That 10M gain resistor on Q1 yields one ton of gain...I even changed this part downward to a 4.7M, then a 2.2M fixed resistor, but, the whole thing still can hum a lot if/when you start tweaking the output cap values larger - to .022, or even .047 as I've used, & like to do. 1M here seems good for now.

Wire (better still, breadboard) the output cap from the collector of Q1 directly to the base of Q2. Ditch the 350K/250K/500K pot that pans between the 2 outcaps. (You can always vary this change later on for different FX,or return to the original setup) Then, take the output directly from the (.022/.047/ even .0068) outcap off the collector of Q2, & make this a direct output to a 500K pot.

In short, you are no longer panning between 2 outcaps at this point. Everything comes off the Q2 one, to a 500K output pot.

Sometimes, I think the result might require a Noise Gate pedal (or any Noise Gate), but, the resultant sizzlerasp/thickbuzz that happens when you turn the 500K gain pot towards max is worth the ride. Gives some really super-sustained, Fuzzrite timbre sounds. This thing can really hang on for great sustain, & trailoffs. A bit of crackle in there, too, @ max gain. The overtones do get more charactersitic when you reach the latter sweep of this 500K gain pot - the thing gets really think & raspy (for me, anyway) Lower this gain pot - even cutting back on yr Vol control - & you can get a very different timbre, cleaner sounds. A very versatile experimenter's mod. this one.
I think one of the defining characteristics of the Fuzzrite is the phase cancellation from combining the outputs of Q1 and Q2 together. Why would you want to get rid of that? Really just makes it into a run of the mill two stage fuzz.

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Post by John Lyons »

I think one of the defining characteristics of the Fuzzrite is the phase cancellation from combining the outputs of Q1 and Q2 together. Why would you want to get rid of that? Really just makes it into a run of the mill two stage fuzz.

Yep.

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Post by Thaxt »

It's a matter of 'driving around the entire vicinity', making collages & variations, just to see what will happen. Vary it for the heck of it, & hear what happens.

I've always gravitiated towards the Beavis Audio Fuzzlab or Screamerlab approach - tweak everything that isn't nailed down, I learn more that way.

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