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Mosrite Fuzzrite (si version) build tips

Started by LJN, December 04, 2014, 07:06:39 PM

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J M Fahey

FWIW I have built tens of thousands discrete transistor circuits and never ever had problems with Ft limiting my designs.

60MHz/100MHz/180MHz is the same , always well above audible frequencies.
Speaking of silicon transistors, of course.

Now on Germanium ones, which have Ft measured in KHz , not MHz, yes, you audibly lose highs if you use them with high gain , which happens for example in old Fuzz circuits and Treble Boosters used by a few old time Guitar Gods, and which justifies the "smooth/warm sound" label.

I'd call that "lack of treble" and in fact can simulate it very well by adding a few 100pF (or 220/470/1000 pf) caps here and there, go figure.

Back to the Fuzzrite, not only I built clones but also had an original one, when they were new  :o  (now where's the [mummy]  emoticon? :( )

A friend of mine's Mother travelled to Miami (remember I'm from Argentina)  and he asked her to buy a Gibson 335 , unavailable here.
To make certain, he gave her a picture.
Boy, was he disappointed!!
She brought back a similar shape Mosrite "335" , which "the nice young salesman told her was better" , and who to sweeten the deal threw in a Fuzzrite, "free of charge/gift" .

Obviously I opened and traced it, and built clones. 8|
We are in an "European Culture" country, so I used what's standard here, BC147/8/9 transistors, not Japanese or American types.

All worked like a charm and had the exact same sound.

That's how uncritical that simple circuit is.

FT?  never cared about it (since all far exceed what I need for Audio).

Hfe? I always bought BC147/8/9 C types, factory guaranteed between 250/500 and in fact clustered around 500, so after the initial tests I stopped measuring them, only checking a few samples every time I buy a new batch (I buy 500 unit lots) .

Thats why we tell you that:

1) we agree that you built your Fuzz properly and it sounds good. :dbtu:
Congratulations.  :dbtu:

2) we agree that different transistors may sound different.

3) we do not agree that Ft is the main parameter affecting sound, quite the contrary, and we worry that somebody building his own clone gets worried about Ft and that snowballs appearing in other Forums (mainly Pedal related ones) and "confirmed true" , because "I saw in SSGuitar and those guys are very serious" .
Just that. :)

PS: in fact I can easily picture pedal supply shops, as, say, Small Bear (just the first one which came to mind) or EBay sellers offering "premium selected 2SC1740 transistors, Ft 140 MHz, as recommended in SSGuitar"   :o


Thanks for being a little more reasonable about it, Juan. I didn't mean to cause any trouble. I have compared my clone to videos of original units, and it sounds very close. So, you had an original? Nice.  I looked up the data sheet to the BC147. It specified hfe of 110, and frequency at 150 MHz. Are these still available? I'd be interested in trying them. Mine already has a buzzy sound, but cleans up quite well when the guitar volume is backed off. It's very responsive. I'd like to hear more about your experience with the original. How long did it sustain? And was it noisy? I couldn't find much information about the original units. So, I'd really like to hear some details from someone who has owned one. Thanks.
If it sounds good, USE IT!

Epiphone Les Paul, Kasino U100- P, Sears 125-XL


I'm also planning to build the Ge version, but I don't have all of the parts yet and I have other projects going on. I'm trying to fix up a motorcycle. I'm gathering parts for three other pedals, as well. So, I'd really like to hear about your experience with an original fuzzrite.  :tu:
If it sounds good, USE IT!

Epiphone Les Paul, Kasino U100- P, Sears 125-XL


Hi LJN, Hey we understand your enthusiasm and we don't want to destroy that desire  :tu: but in this trade there are as many ways to make sound/distortion/buzz/fuzz or plain old good tone, as there are technicians. I remember the first time I worked out how back to back diodes made sustain and crunch and for a short time I glowed with the thought of becoming a tone god but my momentary delusions went poof once a kind old chap gave me a small pile of real technical books, (the ones you have to
purchase to study at Uni).

I then plowed through each type of transistor design explanation looking for the holy grail trick to make a wow circuit. Then one fine day as I pondered what I had learned the heavens opened as it dawned on me that there is NO Best circuit.  :o :o
Why yes,, it finally dawned on me that ALL these circuits have there benefits but come with limitations and quirks. the trick is understanding which ones to use where and that takes time to learn 8|

In the case of guitar sound if you build the best (HiFi standard) amplifier it will likely be a very bland and uninteresting sound which you will probably hate. xP
Fuzz circuits like the one you mention  only tend to work well in front of real tube amps.
In other words the fuzz circuit is actually rather more dependent on the amp that comes after the pedal.
The mojo is a combination of both but the hype tends to focus attention on the pedal. :loco

Reminds me of the old SRV tone thang where everyone ran out to purchase a TS9.99999 or some derivative assuming with that pedal you could access the famous sound. durh??

Sorry kids the mojo factor was the combination of the amplifiers used, any half decent pedal
of similar design would yield the same effect. +/- an electron or 3. ;)

Same goes for Brian May's famous setup.
Check the signal path,, He used the *Normal channel* NOT the other channels.

Signal went TB pedal > one triode stage > a 500K pot (Volume) > power amp.
Even if you used Brian's pedal it would sound vastly different if you used the other channels or another amplifier.
You need an exact combination (or close to it) for the sound to work.
In saying that be aware that other quite different combinations may well deliver the same end result.
Takes years to work that out but comes in handy if like me you need to save a dollar. :-X

In my personal case where a limited budget forces me to use whatever is on hand or cheap to
build/purchase you soon learn there are many ways to get the sound you desire. Sadly pedals are
mostly over rated and vid clips are often misleading because they often don't explain the signal
chain which means you have no way of knowing what it will sound like with your rig. :grr

From that hopefully you will come to realize that pedals are a good way to get some learning
but there is no one pedal known that will sound/perform the same through ANY Amplifier/Guitar
combination. sorry :blank:

Meantime keep at it you are heading in the right direction and with the help of the teck guys who are kind enough to share there wealth of experience and knowledge and you will likely get ahead a lot faster than I did,, no internet in my day so hence a lot of perfectly good transistors went to magic smoke heaven before I got things to work right. :crazy2:

Read up as much as you can, inet is good but too darn easy to get side tracked so a good book
keeps you focused.

Cheers, Phil.

J M Fahey

OK :)

1) you got BC147 "no letter" which basically are the leftovers :(

That said, even those work well :)

2) There is a whole "family" of basically the same general purpose transistor, factory selected  <3)  with certain guaranteed parameters.
What's not to like about that?  :)

So, just because we are talking about that, originally there's BC107/8/9 , standing respectively 45V/20V/20V (in a 9V pedal they are all the same) .

Besides, they are graded by Hfe , and given a letter A/B/C (as said before, no letter means ungraded)


"No letter": "ungraded" :  Hfe 110 to 450 ... which in many cases does not matter.

"A" : guaranteed 110/220

"B" : guaranteed 200/450

"C" : guaranteed 420/500

See that BC108/109 look the same ... in fact BC109 are selected for low noise  8)

There's more:  they are also available in different casings:

BC107 (just to name one type) used an expensive, metallic case  :o

BC147 used a weird polygonal plastic case , with special short, arrow pointed legs, to make automatic insertion easier for machines (remember this was invented more than 40 years ago  :o )

BC547 is what I use today, in a conventional plastic TO92 case:

Still popular in the 21st Century  :tu:  now they are available in SMD packages:

I guess now you know why we LOVE "Cherman Enchineerink"  <3)
These were originally Siemens/Telefunken/Philips developments .

No other company we know is so thorough offering all kinds of possibilities to all manufacturers, without special ordering.

3) Small world indeed :)

Searching around I found a guy who built a Fuzzrite with BC109C  :o (what I did in the early 70's)

4) you ask me about the sound?

That was over 40 years ago, and there was nothing to compare it with (no MXR Dist+ , nor Tube Screamers, nor Big Muff, etc.) .

A friend had a VOX Distortion Booster, the kind which plugs straight in the guitar  :loco , which was very buzzy / "mosquito" sounding.

I liked the Mosrite better.

Sorry can't be more precise .


Thank you for your kind words, Phil. I've been wanting to get some of those books. I have a very limited budget too (actually, no budget). My amp is solid state. It's a 1970 sears 125 XL. It's noisy, but I love it. I sorta came to that conclusion about frequency after looking at all those data sheets. I didn't mean to cause any trouble.  I don't like to cause trouble.  I meant to help. Oh. My guitar is a beat up epiphone Les Paul standard. It has the stock pickups. I always leave my uni vibe clone hooked up, as well. I get a nice cocked wah sound that way when I back off the guitar volume. The pedal, and my amp are all treble. There's hardly any low end. That being said, I have tried this pedal through four different amps. Including my old sears amp. I also have a peavey. The pedal did sound quite different through that one ( think maestro fuzz tone) . I've also tried it with a few different guitars. Stronger pickups tend to make it sound pretty raunchy.
If it sounds good, USE IT!

Epiphone Les Paul, Kasino U100- P, Sears 125-XL


Thanks, Juan. I can't blame you. I love my fuzzrite clone. I did try some C1815(said to be BC109 equivalent)  . They sounded awful, but they worked great in my fuzz face clone. Maybe they're not exact replacements, then. I have to use whatever I can find in scrap electronics. Old TVs, radios CB 's, and stuff like that. So, getting the "right" parts is usually very difficult. I really wanted to build a tonebender mk II, but still haven't found the parts. I always wanted a fuzzrite,  ever since I heard " In-A-Gadda-Da-Vida" when I was 12 or 13. I just loved that sound. If you say these other transistors will work, it's worth building another one someday. Thanks again.
If it sounds good, USE IT!

Epiphone Les Paul, Kasino U100- P, Sears 125-XL