Mosrite - Fuzzrite  [schematic]

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

Just Joined.
I've been looking for a good layout diagram for a Mosrite Fuzzrite. My head is spinning a bit as I've found many different versions online. Does someone have a schematic and layout diagram of the real Mosrite Fuzzrite? It's probably in this thread, but i'm not sure.

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Mike

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Post by allesz »

Hallo, regarding layouts you should find everithing you need on the first page.
For the schematic just google "mosrite fuzzrite schematic" and you should find it, both silicon and germanium.

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Post by ljn »

Hi, everyone. I just wanted to say I switched out my silicon fuzzrite for the germanium version. It has a much nastier sound, but doesn't clean up as much as the silicon version. This is the fuzzrite tone! Nothing else comes close.I can now pull of any Iron Butterfly riff with every bit of crackling nastiness as the original. Adding a decent amount of reverb really makes it sound incredible. If you want the Iron Butterfly tone, build the germanium version. It also does a good Doors tone if you back the guitar volume down to about 8.

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Post by Mr.Grumpy »

I built my own Silicon version of the Fuzzrite, but uses a 0.0068 for the out cap of the first stage instead of the stock 0.0022. I used plastic-case 2N2222, I don't remember if I chose them for any particular gain. I used a 500K pot for the fuzz/balance/tone control and a 50K pot for volume.

I've never played a real Fuzzrite to compare with my homemade one, but WOW, this thing is crazy! No doubt all the weird behavior is due to the Fuzzrite's out-of-phase stage mixing. Some notes are louder and/or bassier, others seem to almost fade out or degerate into super thin fizziness. First sweet spot on the fuzz knob is around 9 or 10 o'clock, nice fat OD sound with the second stage fuzz layered on top. The middle third on the fuzz control isn't very useful, there's a lot of volume drop (due to phase cancellation no doubt) and the tone is pretty thin. There's another 'sweet spot' around 2 or 3 o'clock where it's the classic buzzy, fizzy, super treble fuzz, beyond that the treble screech is almost unbearable.

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Post by BMS1971 »

I have to admit I have some TZ82 and nothing compares to them in a fuzzrite... For Germanium I used MP42B and MP41A (HFE 75 and 95) and it's a loud and amazing fuzz
Attachments
fuzzrite germanium.jpg

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mozz
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Post by mozz »

What are the tz82 testing at?

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Post by bdhact1 »

TZ82 has become practically and cost effectively unobtanium. But, I did get excellent results using two 2SC828P si transistors. They were left over from my Shin-Ei FY-6 build. I found the 2222, 3904, et al... (All the usual suspects) were either just too typical, blase', or unstable to my ears. Of course, tastes and opinions will differ.

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Post by mozz »

Yes, i know that transistor is hard to find but i was wondering what they are measuring at since he said he has some. My book shows they are at hfe 165 @1ma.

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Post by BMS1971 »

Hello guys
looking for information of the latest variants:
1 the one with the "bass side" always on and only the trebles are added instead of blend.
2 the one with a third knob "tone" (pro suzzz fuzzz)
Any schematics or information?
Cheers
Ben

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Post by quantum »

They got some decent gut shot pics at ...
https://www.gbase.com/gear/mosrite-pro- ... 968-chrome

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Post by universalmind »

Dr Tony Balls wrote: 05 Apr 2010, 18:00 cool, thanks, AG!


I tried making the germanium fuzzrite based on the following layout maybe a week or two ago with sockets for the transistors, but got kinda lackluster results. Anyone made that one and have any advice? If I remember right it was pretty screechy at the fuzzier settings, almost like there was something wrong. Then again i've had the same thing happen with a fuzzface build where it sounded like shit on the breadboard but fine when it got into an enclosure.

http://aronnelson.com/gallery/main.php? ... alNumber=2

I tried it with some 2n5088s as a control, and then with some old soviet germaniums I have, which were reading hfe ~200.
I know, I’m over a decade late to this party. Just kill 3 minutes reading my 2c and 50 seconds listening, they’re interesting results considering the components.

The Fuzzrite was the first circuit I stripped naked to find out what each component did, because (a) I’ve always been obsessively curious about something interesting that I don’t immediately comprehend and (b) I realized very early in that you can really get any fuzz sound you want just by subbing slightly different value components. That being said,
The Ge transistors measuring around 200 is WAY too high. The most faithful Ge recreation I ever made was with Q1 hFE = 44 and Q2 hFE = 72. I subbed 6.8nF film caps in place if the stock 2.2nF and it beefed up the tone without losing the Fuzzrite soul. The 4.7M resistor can be replaced with anything from 1M-10M and it will adjust the “character” of the fuzz. I used 3.6M, and these are the results. Seriously, hFE 44 and 77 for Q1&Q2.
https://www.dropbox.com/s/0nwdqtwq6eo4x ... F.mp3?dl=0

If you go the silicon route try something really low like MPSA05 with hFE about 70-80 in Q1 and something pretty greatly like BC183C in Q2, hFE 350ish. I know, the pairing sounds like I should probably be hugging a padded cell for even thinking up a pairing like that, but it sounds absolutely killer with them and 5.6nF caps:
https://www.dropbox.com/s/2xun5b8gzxx7i ... F.mp3?dl=0

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Post by andare »

universalmind wrote: 19 May 2022, 21:52
Dr Tony Balls wrote: 05 Apr 2010, 18:00 cool, thanks, AG!


I tried making the germanium fuzzrite based on the following layout maybe a week or two ago with sockets for the transistors, but got kinda lackluster results. Anyone made that one and have any advice? If I remember right it was pretty screechy at the fuzzier settings, almost like there was something wrong. Then again i've had the same thing happen with a fuzzface build where it sounded like shit on the breadboard but fine when it got into an enclosure.

http://aronnelson.com/gallery/main.php? ... alNumber=2

I tried it with some 2n5088s as a control, and then with some old soviet germaniums I have, which were reading hfe ~200.
I know, I’m over a decade late to this party. Just kill 3 minutes reading my 2c and 50 seconds listening, they’re interesting results considering the components.

The Fuzzrite was the first circuit I stripped naked to find out what each component did, because (a) I’ve always been obsessively curious about something interesting that I don’t immediately comprehend and (b) I realized very early in that you can really get any fuzz sound you want just by subbing slightly different value components. That being said,
The Ge transistors measuring around 200 is WAY too high. The most faithful Ge recreation I ever made was with Q1 hFE = 44 and Q2 hFE = 72. I subbed 6.8nF film caps in place if the stock 2.2nF and it beefed up the tone without losing the Fuzzrite soul. The 4.7M resistor can be replaced with anything from 1M-10M and it will adjust the “character” of the fuzz. I used 3.6M, and these are the results. Seriously, hFE 44 and 77 for Q1&Q2.
https://www.dropbox.com/s/0nwdqtwq6eo4x ... F.mp3?dl=0

If you go the silicon route try something really low like MPSA05 with hFE about 70-80 in Q1 and something pretty greatly like BC183C in Q2, hFE 350ish. I know, the pairing sounds like I should probably be hugging a padded cell for even thinking up a pairing like that, but it sounds absolutely killer with them and 5.6nF caps:
https://www.dropbox.com/s/2xun5b8gzxx7i ... F.mp3?dl=0
I also tried increasing the capacitors and the character was immediately lost. Your versions don't sound like Fuzzrites to me and you also managed to make the Ge and Si versions sound practically the same.

IME this circuit is forgiving of transistors but that's it. You touch resistors and caps and it doesn't sound like itself anymore.
Using resistors across lug 1 and 3 to get the traditional pot values was pretty inconsequential. If anything, using 500k and 50k is better because they give you a tad more bass, which this circuit lacks. I also tried using a reverse log pot for Depth but it lost a lot of the tones across the sweep.

The only deviation I find useful is putting the 22k to ground on a switch for a bass and volume boost. That's what Catalinbread has probably done with their Vintage/Modern toggle switch on their new Germanium Fuzzrite (which IMO sounds phenomenal in demos).

My only gripe with the Fuzzrite is how noisy it is. A small cap (say 10nF) to ground on the input kills the radio star and assorted bacon sizzles but the noise floor remains very high.

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Post by BMS1971 »

universalmind wrote: 19 May 2022, 21:52
Dr Tony Balls wrote: 05 Apr 2010, 18:00 cool, thanks, AG!


I tried making the germanium fuzzrite based on the following layout maybe a week or two ago with sockets for the transistors, but got kinda lackluster results. Anyone made that one and have any advice? If I remember right it was pretty screechy at the fuzzier settings, almost like there was something wrong. Then again i've had the same thing happen with a fuzzface build where it sounded like shit on the breadboard but fine when it got into an enclosure.

http://aronnelson.com/gallery/main.php? ... alNumber=2

I tried it with some 2n5088s as a control, and then with some old soviet germaniums I have, which were reading hfe ~200.
I know, I’m over a decade late to this party. Just kill 3 minutes reading my 2c and 50 seconds listening, they’re interesting results considering the components.

The Fuzzrite was the first circuit I stripped naked to find out what each component did, because (a) I’ve always been obsessively curious about something interesting that I don’t immediately comprehend and (b) I realized very early in that you can really get any fuzz sound you want just by subbing slightly different value components. That being said,
The Ge transistors measuring around 200 is WAY too high. The most faithful Ge recreation I ever made was with Q1 hFE = 44 and Q2 hFE = 72. I subbed 6.8nF film caps in place if the stock 2.2nF and it beefed up the tone without losing the Fuzzrite soul. The 4.7M resistor can be replaced with anything from 1M-10M and it will adjust the “character” of the fuzz. I used 3.6M, and these are the results. Seriously, hFE 44 and 77 for Q1&Q2.
https://www.dropbox.com/s/0nwdqtwq6eo4x ... F.mp3?dl=0

If you go the silicon route try something really low like MPSA05 with hFE about 70-80 in Q1 and something pretty greatly like BC183C in Q2, hFE 350ish. I know, the pairing sounds like I should probably be hugging a padded cell for even thinking up a pairing like that, but it sounds absolutely killer with them and 5.6nF caps:
https://www.dropbox.com/s/2xun5b8gzxx7i ... F.mp3?dl=0
I used with great success, MP1A and MP42B (50 and 80 Hfe). But always found the Ge design odd sounding wen gain is at middle or 0. Is there another schematic than the one from the amp input stage?
Cheers
Benoit

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Post by Lukasen »

One of the many silicon fuzzes that really surprised me is the Mosrite Fuzzrite. I especially like the atypical balance between the gain stages. But, of course, I wanted to get closer to the original and, above all, to understand what was so interesting about it.
Before breadboarding I read from this schematic by Philip Bryant.

Image

The substitution of the volume output potentiometer in some schematics found on the web for the commonly used values of the pots seemed strange to me. In addition, even after my testing, the fuzz was over-bassed too much and compared to the examples of the original effect on Youtube, it did not resemble that much. The output pot forms a high-pass filter with the output capacitor - specifically here with a quite high value.
So I took a regular 100k pot and tried connecting a couple of values around 50k in parallel and played around. In the end, the value of 47k won it.
After that I (like most players here) moved on to transistor selection. But I didn't feel like the sound improved that much. When I tried with a beta greater than 200 (BC547C), there was too hissy, but below 140 it muffled the tone. I ended up leaving the classic 2N3904 in there with betas between 160 and 180.
I tried a different operating point of the transistors or changing the high-pass filters on both stages and the output, but it was no longer a "real" Mosrite Fuzzrite sound. But I still felt that the sound was missing something, it had this weird distorted bass frequencies or something like that.
But then I suddenly saw it with the Foxey Lady 2 knobs version, which is based on the Mosrite Fuzzrite. There they use smaller emitter resistors for temperature stabilization with parallel capacitors (at the same time they reduce the gain and make it frequency dependent - maybe I'm not writing it exactly right). For those who want to know more, this is an excellent article: https://www.electronics-tutorials.ws/am ... tance.html (split emitter resistance is a really powerful weapon).
So I tried them and I found it was just what it was missing!

Image

It is still unfinished on breadboard. I added two SPST switches to change the bass response and a small capacitor in feedback for decoration :-). Yes, and I also added power supply filtering (it is a high-gain circuit after all). I'll see where it goes, but it already makes sense to me. I will be happy if it inspires someone.

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Post by Lukasen »

I have finished breadboard testing a modified version of the Mosrite Fuzzrite. I took my time and consistently played at least several times a week in different effects settings and in different mental states. The condition is that the modified version always makes me happy and changes without feeling there is anything that needs to be improved or changed. And I think it worked.

As a result, I didn't really discover anything new under the sun (the original version is really original and minimalistic and suits most situations). I just clarified how important buffer and low output impedance are in some cases. I was skeptical, so I added it after the tone filter to "just" try it out (that's how it is in most cases when I don't believe in something or I'm not sure). Suddenly it all started to make sense, especially when paired with another fuzz: there was no loss in volume and the Mosrite Fuzzrite character was preserved. But it's also because I focus on buffers and consistency of signal in my work.

The tone filter expands the possibilities of use, especially when the balance is set to 100% for a sharp treble sound, and by closing the tone filter at the same time, we get closer to a sound similar to the setting of around 50% balance, but with a less heavy character and a different tonality.

What the modification does not solve is the lower volume (than one would expect from a fuzz) when the balance potentiometer is set to 50 %, but it is still higher than the input signal, so it is usable. When using a tone filter at the same time, you can get into a situation where the output volume seems to be at a similar level to the input signal. But I didn't want to add another stage for amplification or instead of a buffer, so that the original sound would change (lower input impedance of the common emitter). It's also another way to mod (at least for those who want to kick up the sound a bit more) as some mods show. Just change it to whatever you want :-).

Image

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