A "Fuzz" with a "Face"

[Robert M. Martinelli]

Well,
nothing new under the sun actually, basically it's a FF clone upgraded with metal film resistors, but I wanted it to look different....

It's also a great way to say " we miss you, Jimi"....R.I.P.

Regards

Bob

[52 Bill]

Holy Smoke Bob!

Cool pedal.

[dai h.]

pretty cool. Is that some sort of sheet/sticker?

[Robert M. Martinelli]

Hi Bill,hi dai,
thanks for your comments!
I did the sticker myself, found that pic on the internet, along with others, and it caught my attention, woke up my imagination ( ....and I "imagine" it wasn't a cigarette Jimi was smoking.... ) and gave me some inspiration about the name.

I had to work a little on that pic, cutting and resizing it to match the pedal's dimensions and to keep the controls and foot-switch from interfering with Jimi's face. Then I printed it on a special adhesive paper and coated it with lacquer to protect it. The rest of the pedal is coated with a hi-temp matte black paint.

I had a couple of Vox knobs around, and though I know a couple of Marshall knobs would have been more "vintage correct" I find the Vox knobs complement the thing pretty well from an aesthetic standpoint.

Having the "Master" watching me when I play is both inspiring and scary...( a great "experience" though ).

Regards

Bob

[dai h.]

ah so it's a sticker. Thanks for the explanation!

[Danelectron]

Robert, That pedal looks awsome! I have been looking at some schematics and am cosidering building one. Can I ask you how the input jack is wired on yours? Some schematics appear to use a TRS type input and I don't understand what is happening there.

I've included one schematic that I'm considering. Thanks, Dan

[Robert M. Martinelli]

Hi Dan,
The FF is one of the simplest circuits to build, yet one of the most rewarding in terms of tone....it's also very easy to tweak.

The input socket is a simple 1/4" stereo, the "tip" terminal is the input, the "ring" has to be connected to the battery's positive terminal, this way, when you plug a mono jack in, the battery positive gets in contact with the jack's ( circuit ) GND ( remember the FF BJTs are PNP ), this way the jack operates also as a power switch. In case you plan to use your FF together with other stompboxes, be aware that you'll most likely need to supply it using a separate power supply ( or a battery ) because most "commercial" stompboxes have the NEGATIVE to ground, so supplying all your pedals using the same power source would result in a short circuit.

One word of caution - to build a vintage-correct FF you'll need a couple of PNP Germanium BJTs. The problem with Ge BJTs is that they're pretty leaky devices, so I strongly encourage you to read R.G. Keen's guide to the FF and how to select the best Germanium BJTs to use when building one.

Hope this helps

Best regards

Bob

[Gibsonman63]

A little late to the party

I just had to comment. That is a really cool pedal and looks like it would be a fun build.

Providing that you use a separate power supply, will this guy play well with other pedals. I don't have a super long effect chain, just a tuner, a Wah and a TS-9, but it would be nice to have a fuzz to play with as well.

[Danelectron]

Bob, Thanks for the info! My thoughts on the input was that it was providing switching, but I wasn't sure what was going on. Does this mean the battery life will be shortened if the instrument cable isn't unplugged?
I did stumble across R.G. Keens article. I believe it was attached to some schematics also. Good info. Another article I read dealt with some other choices that are supposed to be more reliable. I found some CV7003s doing a search for germanium transistors. I ordered 2 to try. The invoice listed them as OC44s so I'm not sure what I'm getting. I understand the CV7003 is similar, but militay spec. (for better or worse). I don't remember the manufacturer, but the jist I got from the article is that there is no real guarantee from batch to batch or manufacturer for that matter, but the gain is the main factor. They spec'd these at a minimum gain of 100 so I thought I'd try them. Though I'm not sure if the spec is just a spec or if these are tested and guaranteed. I'm not overly concerned about building to the EXACT design, but do want a good sound. What are thoughts on this choice?

I built a little "fuzz box" in high school electronics too many years ago. It was a Heathkit project that was just a little bag of components with a circuit board for about 12 bucks (does that date me?). The teacher would sell us little bakelite boxes to mount the board and battery in. The thing had an awesome buzzy kind o' fuzz and provided some cool boost as well. Reminded me of some of the fuzz the Beatles used around the Revolver / Rubber Soul days.

I had also thought about building this into an amp as an on board effect, maybe with a remote foot switch. Can you think of any issues I may have with this? I would have to set up a voltage divider or maybe just tap a wall wart off incoming power.

Thanks for your attention, Dan

[Robert M. Martinelli]

Bob, Thanks for the info! My thoughts on the input was that it was providing switching, but I wasn't sure what was going on. Does this mean the battery life will be shortened if the instrument cable isn't unplugged?.....

.....I found some CV7003s doing a search for germanium transistors. I ordered 2 to try. The invoice listed them as OC44s so I'm not sure what I'm getting. I understand the CV7003 is similar, but militay spec. (for better or worse). I don't remember the manufacturer, but the jist I got from the article is that there is no real guarantee from batch to batch or manufacturer for that matter, but the gain is the main factor. They spec'd these at a minimum gain of 100 so I thought I'd try them.......


.....I had also thought about building this into an amp as an on board effect, maybe with a remote foot switch. Can you think of any issues I may have with this? I would have to set up a voltage divider or maybe just tap a wall wart off incoming power.

Thanks for your attention, Dan

Hi again Dan,
yes, forgetting to unplug the jack at the input would result in shortening the battery's life.

As per R.G.'s advice, FF will sound "better" using BJT's with gain between 60 and 130.

The problem with Germanium BJTs, as I mentioned, is their tendency to be "leaky". Leak is represented by current flowing between "E" and "C" without driving the BJT's "B". If you test a Germanium BJT with your DMM's BJT tester, your instrument will drive the Base with a small current and measure the C-E current, so it won't be able to discriminate the leak current from the "normal" current.This means your DMM will read a gain which will be higher than the real one. To state your Ge BJTs' real gain, you have to measure leak first ( R.G. Keen's pages show "how", and include a "leak tester" schematic ). Ask your supplier if the stated gain of 100 takes leak current into account.

If you plan to incorporate the thing inside an amp or a board, the caveats about a separate ( positive-to-GND ) supply still apply, while, to operate it by means of a footswitch, I suggest you use a "signal DPDT relay" inside the amp/board, operating (supplying) the relay's coil by means of the footswitch. Add a reverse-biased diode ( 1N400X ) in parallel with the relay coil to dampen the current flowing back from the relay's coil when the relay gets switched off.

Hope this helps

Best regards

Bob

[Danelectron]

Robert,
Yeah, good info. Do have a recommendation on a schematic? I had planned to use the Fuzz Face from R.G. Keens page with the Jimi mods.

Thanks again, Dan

[Robert M. Martinelli]

You can start with that and, in ( the unlikely ) case you're not satisfied with the results, you can easily tweak some values 'till it sounds good to your ears.

Cheers

Bob

[Danelectron]

Cool, Thanks Bob!

[Shea]

If you want to build one with BC 109s, would you use a negative ground?

[HTH]

If you want to build one with BC 109s, would you use a negative ground?

BC109s are NPN transistors, so yes, negative ground.