Fuzzrite help needed

E9th
Regular Member
Posts: 34
Joined: Tue Dec 28, 2010 4:09 pm
Location: Washington
Contact:

Re: Fuzzrite help needed

Postby E9th » Wed Jan 19, 2011 1:30 pm

Thanks dubtrub, that appears to be the germaniuim version, 1st version I think.. Mine is the silicon version.
amazing how different they are. Ive read that the germ version was too unstable and didnt react well to cold floors, thus the switch to silicon transistors. IM glad the silicon version doesnt have the footswitch mounted to the board. yikes

They must sound vastly different as well. :?:

Mr. Bill
Top Producer
Posts: 678
Joined: Tue Aug 19, 2008 12:15 pm
Location: Chicago, IL
Contact:

Re: Fuzzrite help needed

Postby Mr. Bill » Wed Jan 19, 2011 3:37 pm

Yes, on Alpha pots the A stands for audio (taper). Actually an audio taper might work well as the depth control, due to the differences in the gain from the two different circuit stages. I might have to specifically test that theory out.

And yes, those photos are of the Germanium versions. Ed Sanner has been quoted as saying that the germanium versions would sometimes react to the cold temperatures found on concrete floors. This is why he redesigned the circuit with the silicon transistors. I have tried both versions of the circuit, and I have found that the differences in the sounds are very minor. The transistors are used in a very non-linear mode, so the distortion characteristics of the two types of transistors really doesn't matter much.

My personal take on the pots is that I strongly believe that all the original units came with two 350K - 500K pots, the same pots that were used in the guitars at the time. The 30K value was probably caused by reading the value of the volume pot with the depth pot turned all the way up, which places the 33K signal balance resistor in parallel to the volume pot. This value was marked on a schematic that has been duplicated and copied from the web for at least 10 years now, and has become the default value.

About 25 years ago, a fellow I worked with asked me to fix his Fuzzrite pedal. He too had used the case to house some other circuit and wanted to return the pedal back to stock. I had never seen the insides of one these before. He handed me the case, the circuit board the switch and the two pots. Unfortunately whoever took the pedal apart decided to use all of the original connecting wires for the other project and so I had no idea as to how the parts went together. So I sat down with a pad of paper and drew out the circuit, the two pots, the two jacks and the switch and tried to connect the dots to make a working pedal. I was able to figure out the basic circuit and the wiring, the only thing that I couldn't figure out was the footswitch with that cap wired on it. I eventually gave up and just wired it as a complete bypass switch. It wasn't until many years later while searching the web, did I find out how the switch was supposed to be wired.

Sorry for the long story, but that pedal was the same version that you have. It had two matching 350K pots. I own a third version silicon Fuzzrite with the couplate (encapsulated circuit) and it has two matching 350K pots. I should pull mine apart and see if the pots are linear or audio taper. I'd suggest just order two 500K Gibson pots and go for it.

E9th
Regular Member
Posts: 34
Joined: Tue Dec 28, 2010 4:09 pm
Location: Washington
Contact:

Re: Fuzzrite help needed

Postby E9th » Wed Jan 19, 2011 5:31 pm

dont apologize for the long story. I loved every word of it. :D

Its odd that after all these years, with all the clones made, and with all the original fuzzrites that must still exist intact, that we dont know for certain the correct pot values or tapers. I would tend to go with your idea Mr. Bill, that they used pots they used in guitars, that would make GOOD sense , whereas a 33K makes very little sense to me.


I hope I get that switch wiring correct. I am going off the picture I posted at the beginning of the thread and one or two others ive seen online. I have a very crude layout drawn, perhaps I will scan and post it (its at work and Im home sick).
There are not any caps or resistors that are not on the board are there that might not be visible in those photos? (other than the cap on the footswitch). I ask cause you mentioned a "signal balance resistor". Ive built a bunch of kit pedals (BYOC..good stuff), a couple kit amplifiers and managed a few simle repairs , but generally I am really a noivce at this stuff and dont understand electronics at all.

it wouldnt hurt anything to grab an extra 500K and try two 350's.
Thanks for the help, much appreciated!

dubtrub
Administrator
Posts: 3772
Joined: Sun May 04, 2008 10:12 am
Contact:

Re: Fuzzrite help needed

Postby dubtrub » Wed Jan 19, 2011 8:05 pm

There are a couple of members on this forum that are in periodic contact with Ed Sanner. It sure be would nice if they would ask him to draw up a schematic of the Fuzzrite since he's the person that originally designed them. Artie where are you? ;)
Danny Ellison

Mr. Bill
Top Producer
Posts: 678
Joined: Tue Aug 19, 2008 12:15 pm
Location: Chicago, IL
Contact:

Re: Fuzzrite help needed

Postby Mr. Bill » Thu Jan 20, 2011 10:39 am

I'd love to hear the real story from the man himself! The Fuzzrite is just a simple circuit compared to all of the other things that he designed for Mosrite and a lot of other companies.

As for the pot value, the same wrong schematic has been quoted for so long, it has become Gospel. The guys that are cloning these pedals have no want to correct the myth, as it takes away from their own mystique. There should be 2 transistors, 4 caps, 5 resistors on the board and the one cap on the footswitch. All of the parts on your version were mounted on the board, unlike the earlier versions, where sometimes the 2-0.002uF caps connected the board to the depth pot.

I have a schematic that I have drawn up, but I have no real reason other than my own history and experience to believe that it is 100% accurate. And as we all know here, all things Mosrite including the pot values could have been improvised as fortunes and demands required. Maybe I'll send my schematic to Sarah so she can replace the really wrong version that she has on her site.

Last night I pulled my Fuzzrite out and checked the pots, they are both audio taper. I will help you to get it wired up back to the way it left the factory.

Bill

E9th
Regular Member
Posts: 34
Joined: Tue Dec 28, 2010 4:09 pm
Location: Washington
Contact:

Re: Fuzzrite help needed

Postby E9th » Thu Jan 20, 2011 2:06 pm

You are too kind Mr. Bill. Thank you. 8-)
I will report back once the other parts arrive, which should be any day now hopefully.

E9th
Regular Member
Posts: 34
Joined: Tue Dec 28, 2010 4:09 pm
Location: Washington
Contact:

Re: Fuzzrite help needed

Postby E9th » Tue Feb 01, 2011 9:37 am

I have been really ill, still am, and havent had a chance to do anything with this yet. I didnt juts fix it and run away. Hopefully whatever this is will go away soon and I'll be able to fire up the iron. Cheers

Mr. Bill
Top Producer
Posts: 678
Joined: Tue Aug 19, 2008 12:15 pm
Location: Chicago, IL
Contact:

Re: Fuzzrite help needed

Postby Mr. Bill » Tue Feb 01, 2011 10:42 am

Sorry to hear about your illness. This time of year there's a lot of that going around. Get well soon!

E9th
Regular Member
Posts: 34
Joined: Tue Dec 28, 2010 4:09 pm
Location: Washington
Contact:

Re: Fuzzrite help needed

Postby E9th » Sat Feb 05, 2011 10:58 am

Thanks Mr. Bill, man that was THE worst flu Ive ever had. Three weeks exactly I was laid out. Finally felt a wee bit better this morning and jumped on the fuzzrite. IT WORKS :D

but...its very quiet. It only hits equal to bypass volume with the fuzzrite volume knob turned all the way up. I assume this isnt normal? With both knobs maxed it sounds fantastic like a classic fuzz should, tho it could still be a touch louder. I used 500K audio taper for both pots and put 1.2M resistors across the outer lugs of the pots in an attempt to make them close to 350K. Measuring the pots now I get 358K on the fuzz pot, but only 180K on the volume pot at max. I am guessing this is the problem with the volume. Perhaps the online schem IS correct and that pot value should be much lower like maybe i should use a 50K? If I wanted to get close to a 33K like the online schem, what would be the correct resisitor value to put across the lugs to get me closest? 100K maybe? almost there!! Thanks again for your help!

Heres a picture of how I wired it:
Image

E9th
Regular Member
Posts: 34
Joined: Tue Dec 28, 2010 4:09 pm
Location: Washington
Contact:

Re: Fuzzrite help needed

Postby E9th » Sat Feb 05, 2011 8:20 pm

it seems the Depth or Fuzz control has a weird taper too. Its guts the volume in the middle and is loudest at either end of the knob. I will try the 500K Linear (if I can find one with a split shaft) and 50K audio and report back.


Return to “Amp Tech Q&A and Repair Shop”

Who is online

Users browsing this forum: No registered users and 9 guests