D*A*M - Meathead

Renegadrian · Post by **Renegadrian** » 29 Oct 2009, 12:43

Can someone suggest me anything?! Got some problems with mine...
https://www.freestompboxes.org/viewtopic ... ead#p80195

roseblood11 · Post by **roseblood11** » 30 Oct 2009, 22:13

Hi,

the orientation of Q1 is wrong in Mike´s schematic. Emitter has to go to ground...
http://pdf1.alldatasheet.com/datasheet- ... N3904.html

Immo

Renegadrian · Post by **Renegadrian** » 31 Oct 2009, 01:11

Yeah I know...In fact it kinda worked when I twisted its legs...So found about it after I built it...
I dismantled the circuit, and put it back again following a layout I made starting from MacElroy's, it's a lot more compact of his but yeah it's his layout and I left the credit due.
It works, but I got no terrific fuzz machine, but a bland overdrive...It has no power and no meat here, just some f..king tea with milk...

Here's my layout if anyone should need another...

McElroy0717 · Post by **McElroy0717** » 31 Oct 2009, 02:24

Renegadrian wrote:...It works, but I got no terrific fuzz machine, but a bland overdrive...It has no power and no meat here, just some f..king tea with milk...

Something must be off on your pedal.

I've built 4 of these now and each one has been loud and very heavy sounding.

McElroy0717 · Post by **McElroy0717** » 31 Oct 2009, 02:38

Looks like you have your 10uf going to the Base instead of the Emitter of Q2 (BC182L)
If it isn't working right, you might not want to post it as "verified"

devastator · Post by **devastator** » 31 Oct 2009, 13:23

mine is like the Renegadrian , nothing really lood and no really a lood fuzz machine.

Diamond · Post by **Diamond** » 31 Oct 2009, 21:19

McElroy0717 wrote:Looks like you have your 10uf going to the Base instead of the Emitter of Q2 (BC182L)
If it isn't working right, you might not want to post it as "verified"

+1 BTW, both input and output caps should be 22nF. And I also think C5 should be 22uF instead of 10uF.

McElroy0717 · Post by **McElroy0717** » 31 Oct 2009, 22:20

Diamond wrote:
+1 BTW, both input and output caps should be 22nF. And I also think C5 should be 22uF instead of 10uF.

Older versions used the 10nf & 22nf. Current version is 22nf for both. "Dark" version uses 0.47 & 0.1uf.

Definitely 10uf for C5.

Renegadrian · Post by **Renegadrian** » 01 Nov 2009, 11:17

McElroy0717 wrote:Looks like you have your 10uf going to the Base instead of the Emitter of Q2 (BC182L)

Ok, fixed C5 position...

devastator · Post by **devastator** » 01 Nov 2009, 15:22

I cheked the values I used in mine and nothing is wrong but I still have a a fuzzy overdrive not a fuzz machine like I can hear on D*A*M website.

Renegadrian · Post by **Renegadrian** » 02 Nov 2009, 00:47

Third time and last time! I got it working! I used the above layout with C5 correctly inserted...And voila' I got a Meathead!!! Nice pedal! Got to thank McElroy for his layout, altough I shrinked it a lot it just started as the layout he made!!!

McElroy0717 · Post by **McElroy0717** » 02 Nov 2009, 04:49

Glad you got it working

No greater feeling that making something work after it gives you trouble. Post some pics and show it off

devastator · Post by **devastator** » 02 Nov 2009, 12:49

Someone can put a youtube link where we can clearely hear the sound of the beast ? I've some doubt about it, I changed transistors in mine and the sound didn't change. It's more like an overdrive than a real fat fuzz.

Renegadrian · Post by **Renegadrian** » 02 Nov 2009, 15:47

Well, it's not so "fuzzy", at least mine...
One more thing - the pink one had this circuit in?! I mean the capacitors changes...

Renegadrian · Post by **Renegadrian** » 02 Nov 2009, 16:17

McElroy0717 wrote:Glad you got it working No greater feeling that making something work after it gives you trouble. Post some pics and show it off

Yeah I agree! I cannot post pics, as it's not a finished pedal, but just the vero board with "flying wires"

devastator · Post by **devastator** » 02 Nov 2009, 17:18

well in watching I realized my pedal sounds right . Just the fuzz isn't like I thought.

I think I'll tweak it for the fuzzy sound I want

Hilbishnk · Post by **Hilbishnk** » 04 Nov 2009, 21:56

I am having some issues with my meathead's decay it sounds pretty good while playing, but when A note is sustained it dies out very abruptly, with some fizziness at the end of the notes decay. I believe its to do with transistor selection. From what I can tell normally high gain transistors are used. The BC239C (used in all current production meatheads) has a beta typically around 300 , and the BC182L has a beta from 125-500 (most of mine around around 200). If I understand the circuit correctly the gain of the first transistor contributes mainly to the voltage drop across the second stage collector resistor. So my question is should the second stages beta be larger then the first and if that's the case given a BC239C (Q1) with a gain of 300-400, what should the BC182L (Q2) be?

John Lyons · Post by **John Lyons** » 05 Nov 2009, 15:23

What is the voltage on Q2's collector?
It's probably just misbiased.

John

Hilbishnk · Post by **Hilbishnk** » 05 Nov 2009, 15:48

What should it be biased to? I know traditionally a fuzz face is biased around 4.5V at Q2's collector. But from what i have read on the DAM forum it seems the meathead is biased differently.

MoonWatcher · Post by **MoonWatcher** » 05 Nov 2009, 18:22

It just dawned on me today that the Meathead and RoG's Sili Face (and SF 2) are fairly similar. I built the SF long before I even knew about the MH, or that it was YAFF.

It would be easy to swap out a handful of stuff on your SF build to make it a MH, or you could combine the best facets of all 3 to your specific tastes (which is what I did).

Oddly enough, I tweaked my SF some months ago for transistors with gains that are pretty close to the MH. I guess that most of these YAFF thingies all seem to terminate to a similar end point, when you get to tweaking them.

I did add the 250K pre gain pot on the input, which does work wonders (for me) with these types of YAFF circuits. Really makes a lot of noisy BJT's work quite well.

Just some FYI that probably most folks would come to realize eventually, anyways.

D*A*M - Meathead [traced]

DAM - Meathead [traced]