Keeley Fuzzhead PCB Layout

[liddokun]

So I was thinking of building one soon, and I came up with a layout. It's not verified, however, I'm posting it anyways for anyone who wants to build one.
I'm 90% sure it's correct, however I'm only human. I have yet to build it.

Schematic and article here:
http://www.angelfire.com/planet/bluesdeville/robert_kelly_fuzzhead.pdf

Note: R6 was oddly labeled, so I wasn't sure what the value was, I just put what it looked like (1.1K). Also, there is not R15, Mr. Keeley seemed to have went up to R14 with the labels, and went directly to R16 for the next one. There are 20 resistors in total, none of which are labeled R15.  SW1 is a spst switch, one lug to the SW1 pad, one lug to ground. Engaging it will put the two diodes D1 and D2 in parallel with C6 and volume, adding more distortion. Volume pot is 50k, but 100k can be used for more volume.

[bean]

I think you could tighten up this layout considerably if you orient more of the resistors and trannys vertically rather than horizontally. It would let you get it in a 1590B much more easily 

[liddokun]

I'm a bit lazy at the moment. I'll take another stab at it when I have a chance.

[frank_p]

I tought you were taking a break Nam... What happened ? 
Who are blues DeVille ?  They are from Montreal ?
I am trying to verify but it's no use, crossed-eyes.
Hope tomorow I will find some time to double check.
There are some audio on the net about this Fuzz ?

[Ben N]

I wonder if Keeley has changed the design for this pedal. In the manual at his site http://www.robertkeeley.com/manuals/fuzz_head.pdf he refers to a Darlington pair rather than a differential pair. This could just be marketing fluff/disinformation, or it could be that he traded the original Ge boost + differential fuzz-based circuit for something perhaps more like a Ge boost + Bazz Fuss? Anybody have a recent one to crack open?

[liddokun]

I tought you were taking a break Nam... What happened ? 
Who are blues DeVille ?  They are from Montreal ?
I am trying to verify but it's no use, crossed-eyes.
Hope tomorow I will find some time to double check.
There are some audio on the net about this Fuzz ?

I tried to take a break...it was far to difficult. You can never really take a break from this hobby. 

Ben, I suppose he did change the design. The manual states that there is also an internal tone trimpot, which was not on the schematic. One could probably work it in, it probably has something to do with C3 and the input cap. Also, in the site where I got the schematic, the article starts off saying it was called the Differential Fuzz, now called the Fuzzhead. Will it work based on the provided schematic? I'm not sure, but I'm going to build this and find out.

[Ben N]

Ben, I suppose he did change the design. The manual states that there is also an internal tone trimpot, which was not on the schematic. One could probably work it in, it probably has something to do with C3 and the input cap.

The tone pot is right next to C3.

[liddokun]

Ben, I suppose he did change the design. The manual states that there is also an internal tone trimpot, which was not on the schematic. One could probably work it in, it probably has something to do with C3 and the input cap.

The tone pot is right next to C3.

I can 't seem to find it anywhere on the schematic I have.

[Ben N]

Sorry, I meant in the photo in the pdf manual at Keeley's site. It's not in the schematic, AFAIK. I would have expected there to be 2 caps with the pot between them, but the pic certainly does not confirm that.

[liddokun]

So either there has been further revision to the circuit, or he's leaving certain stuff out. I'm going to lean more on the first one, that posted schematic is from 2003 I believe. I'll tighten up the layout, see if I can work in a tone pot. Although I don't find it necessary, I'm probably just going to have 2 difference values for C3 and make it switchable on a DPDT.

[Ben N]

I agree. Keeley has left stuff out of schematics before (the Java comes to mind), but this one was posted as part of a DIY column in Premier Guitar magazine before he released the Fuzzhead as a product, and it looks as though it would work. Maybe he just wanted the production version to have more bells and whistles. Interestingly, he got the relationship between resistor rating and noise wrong, AFAIK. But what do I know?

[Paul Marossy]

Hey, when someone verifies the PCB layout, let me know! I am a little intrigued by this circuit.

[frank_p]

Nam,

The connectivity-nodes are verified on your layout compared to the schematic in the pdf.
Verify the pinouts of the transistors, I did not compared to a datasheet.
Only thing, R1 seems to be 1M rather than 1K Ohms.
Did not check the values of the parts since they carry the same labels in the schematic and in the pdf, so pretty easy to reverify.
Everything else is looking fine !!

We celebrated the birthday of my mother this evening, but my father was a bit rough with me so, did that patience-verification game to calm down.

Seems to be: GOOD WORK !!
Yours
F.H.P.

P.S.: Does someone knows how Q1 and Q2 are interacting together ?  Does this arrangement carry a specific name ?

[liddokun]

Frank,
Thanks for looking it over. I must have selected "K" for the value instead of "M" for the value in DIY layout creator. Transistor pinouts are correct from the datasheets I'm looking at.
The positive of D1 and negative of D2 go to an unlabelled pad....this pad is connected to an spst switch, which basically connects D1 and D2 to ground or not to ground.

I've gone over the layout and made a tighter version...




Hopefully this one is ok too.

[frank_p]

The positive of D1 and negative of D2 go to an unlabelled pad....this pad is connected to an spst switch, which basically connects D1 and D2 to ground or not to ground.

Ok, at first I was . But wherever anybody wants to hear the circuit without diodes it's OK...
Did you breadboarded Nam-An ? (I mean did you breadborded it without diodes ?)
Since I've checked it out, I should solder it... (Or bread-board it)...

I don't have the specific numbers of the transistors in my bins, but I could find such transistors that carry the gains...
I will have to check the datasheats unless somebody already have some gain ranges...

But still I would like to have some insight on the interaction between the Q1 and Q2 transistors.
I mean, I hate to solder parts that I don't know the the pupruse of...

...
F.H.P.

This is no negative toughts, but only to understand more...
Please anybody...    If you could instruct us...

[frank_p]

 





Nobody ?

hhhm...<
FHP

[frank_p]

SHut

Or....

[Ice-9]

@Frank_p  q1 -q2 look just like a long tailed pair which is quite common in amplifies, here is a link on how they work. I'm not sure if it aplies to your question though.

http://www.ecelab.com/long-tailed-pair.htm

[liddokun]

The positive of D1 and negative of D2 go to an unlabelled pad....this pad is connected to an spst switch, which basically connects D1 and D2 to ground or not to ground.

Ok, at first I was . But wherever anybody wants to hear the circuit without diodes it's OK...
Did you breadboarded Nam-An ? (I mean did you breadborded it without diodes ?)
Since I've checked it out, I should solder it... (Or bread-board it)...

I don't have the specific numbers of the transistors in my bins, but I could find such transistors that carry the gains...
I will have to check the datasheats unless somebody already have some gain ranges...

But still I would like to have some insight on the interaction between the Q1 and Q2 transistors.
I mean, I hate to solder parts that I don't know the the pupruse of...

...
F.H.P.

This is no negative toughts, but only to understand more...
Please anybody...    If you could instruct us...

You should also have a look at the article that came with the schematic that I posted above.  Robert Keeley provided a lot of information about the circuit. The diodes are on a switch in the Fuzzhead that is currently being sold, so I guess I just wanted to make it similar. It just adds assymetrical clipping stage in parallel there. 

[frank_p]

OK Thanks Mick and Nam.  I now have a name to search this configuration.
Thanks again !