Black Arts Toneworks - Black Sheep [traced]

[rocket8810]

Also, I just noticed, and I'm not sure if the one you have had the transistor backwards or the pinout was backward, but Q3, without a doubt should go from left to right CBE,not EBC like the rest of them. That's comparing the trace to the board I had, and the schematic for the original.

I should have the schematic done tonight, or if I get some time tomorrow during my lunch I'll finish it up.

Again, awesome work man. Thanks.

Hi,
Yes I had quite a hard time at unsoldering all these parts. The 3PDT was especially difficult !! I used a solder pump, cause' IMHO it's what works best and quick so that your components won't get overheated. Resistors are quite easy to lift, capacitors soldered so close to the board not.

Regarding your last post I'm not sure of what you say because after looking closely at my board I can assure you that
on mine all three transistors are oriented the same way, i.e. C B E front left to right.
Transistors are noted as following: 2N
5089
-H41

Maybe you can see that in one of my pictures

IMG_0669.jpg

Thanks for drawing the schematic !

Lol. I figured about the I put, so no biggy. But I'm certain something is odd with Q3 on yours. On the one I had Q3 was flipped, take a look at the picture of the board when I got it at the top, and on the schematic the output leaves from the collector of each transistor, while the emitter goes to ground through an electrolyic cap and a resistor. If all of the transistors in yours are CBE, then Q1&Q2 would have the collector grounded, and the emitter the output to the next stage, or if they're all EBC, then Q1&Q2 are correct, and Q3 is the ones that's backwards. It seems hard for me toe explain, but take a look at the GGG schematic I posted when I got the pedal and first wanted to figure it out.

I can't imagine the time it took to get this appart to get a trace. I may have made a schematic, but without your hardwork I couldn't have do it man.

[V1nce69]

Yes I see what you say about the other picture: the transistor on the left labeled Q3 is reversed. It would definitely very interesting to know if there were different versions of this pedal and different transistors used. On the back of my pcb it's written v1-3. I also noticed that on mine the components aren't labeled at all, which is not the case on the one with Q3 reversed... Can this be an Explanation ? The type of transistors used in the first photo shown at the beginning would definitely help to sort this out. I'll have a look at the GGG schematic and try to compare it to my pcb v1-3.

I WAS WRONG ABOUT THE PINOUT IN MY LAST POST. FROM LEFT TO RIGHT IT'S E-B-C AND NOT C-B-E AS BEFORE STATED.

2n5089 pinout reference:
http://alltransistors.com/pdfview.php?d ... child_semi

According to my board Q3 collector goes to ground through the 10uF cap and the 1k5 resistor, while Q2 emitter goes to ground through a 10uF cap and a 1k5 resistor, and Q1 emitter also goes to ground through a 10uF cap and a 1k8 resistor.
tha'ts seems strange indeed. ???????? Usually it's the emitter tha'ts connected to ground.

There might as well be an error, who knows.

Maybe I still have to take out Q3 and socket it and see what are the differences.

And yes it took me quite a few hours to get it torn apart and it looks like I'm not yet done...

[V1nce69]

I took a look at the GGG Bee Baa schematic and according to it all emitters are connected to ground through a cap and a resistor.

This would indeed mean that my board has Q3 oriented backwards

According to the layout on my board transistors should be oriented like this to have emitters connected to ground through a cap and a resistor:
from left to right:

Q3 C-B-E
Q2 E-B-C
Q1 E-B-C

[rocket8810]

Well glad to know I'm not completely crazy then. Haha. I had v1-3 too, so my guess is that the Q3 in yours has a backwards pinout for some reason. I know I've had some transistors all from the same lot that had a reverse pinout, but were perfectly fine for use. I'm certain the schematic is 1:1 with the layout. Just need to make sure that Q2 does have a 1nF between the Base and Collector. I'll make a layout and see if when it's built if it works the same.

[V1nce69]

I'm now down with the tear down. I nearly took out everything away from the board.

One important thing that was missing in my drawing: the orange link connecting the base of Q2 and the 100k resistor is also connected to the negative side of the 1 µF cap above Q2.


Here's a pic a the board as it is for now. You clearly this small link: ti's in the angle of the trace going to the round pad of the 1µF cap above Q2.

BAT Black Sheep - pcb without transistors

I now to but back everything in it's place...

[rocket8810]

Awesome. That's how I have it in my schematic, so we should be good to go!!!

[V1nce69]

Board completed and cleaned with isopropyl alcohol.

First resistors back in:

Resistors back in

Completed:
Note that I replaced the1µF electrolytic caps, with 2 polyfilms and 1 tantalum

completed

Other side, cleaned too:

other side

[rocket8810]

Wow. Looks so much cleaner without the 1uF electrolyitcs, not to mention the quality soldering job. I wonder if the tone will be affected by the switch form electrolytic to poly and tantalum.

[V1nce69]

Thank you for the nice comments. I do agree with you. In fact my first idea was to put 3 polyfilm caps. But the space between the 3PDT and the socket was way too small...
As for soldering I use a Weller PU81 with temperature set to 300°Celsius. The cleaning with isopropyl alcohol also helps removing all the soldering flux, thus the board looks much nicer.

It's hard to say if there's a change in sound due to the new caps. I should have two to be able to compare side to side. The thing that still puzzles me is the role of Q3. I tried it both ways, CBE (as in yours) and EBC as it was in mine. It seems to be better with CBE, but it also works the other way round; it jus seems to be harsher.

One interesting thing I noticed is the big difference in sound/type of fuzz when trying different types of transistors for Q3.
- 2n5089, stock, quite harsh, with a kind of fizzy aggressive decay
- 2n5088, same as 2n5089
- MPSA18, interesting, more open sound, better longer decay. Also tried it for Q1 as in the Pharaoh, but it didn't change much there.
- 2n5133 (bought from SmallBear), stronger but better fuzz, long nearly chorusy decay.

There's definitely something to try there. It would also be interesting to know the hfe of the transistors used to make a better comparison, but for now the multimeter I have cannot do that.

The other part I'd like to isolate is the tonestack as it is so muffled. I know this pedal is aimed for doom but to my ears it's a bit too much, at least with my settings (4001 Rickenbacker, SVT II PRO, 4x10 HLF). One should try to alter the values and see what it does to the sound.
I'll have to wait for your layout to play some more with this design I think

Anyway mine is now for sale on Ebay, with other pedals too, if you're interested.

[rocket8810]

Interesting about the transistors, I was planning on trying differs transitors and mpsa18 was on the top of my list. I'm definitely thinking that the Q3 on yours was put in backwards by mistake. It makes no sense based on the schematic for the original beebaa, and the one I had, which had the same version labled on the board, that it would be installed the way it was on yours.

It's funny that your selling yours. I was going to say if you sent it to me I could test the transistor gains with my DCA55. Tout that would have also been feasible if you're in the US like myself.

As for the tonestack, if you checkout the original schematic there were 2 different tonestacks that you could switch between the two, one is a notch filter that stays in the black sheep, the other a high pass filter if I remember correctly. I think that the idea for having the switchable input caps is that you can control the amount of bass, and that coupled with the notch filter gives literally a ton of tonal options. It's definitely going to be easy to play with the tonestack of your not happy with it. I myself want to get more bass out of it, but don't want it to get muddy, buts that's me.

One of the guys over at tagboardeffects made a layout for me, as I haven't had any time to make it myself. I can post it over here. But I am also going to work on making my own layout to see if I can get slightly different dimensions.

[Ebethron]

Has the layout on the tagboardFX been posted? I can't see it anywhere and neither in their forum?

I really appreciate this one gentlemen!

Hope that we can start verifying this one soon!

[V1nce69]

I did check the original Bee Baa schematic and noted a few differences that surprised me:
- the 470pF cap doesn't exist in the original; what is its purpose here ?
- the input cap selector is placed after the gain pot; why ? How would it differ it was placed before ?
- the small caps near the transistors, 2 have been upped and 1 downed (as you noticed it
- the 1uF capacitor, following the 22k and 47k parallel resistors just before tone pot, is a 10uF in the original
- and a few small differences in some capacitors, but not so relevant I think.

The position of the 47uF cap near Q1 has a contact with the 330pF cap and the 100k resistor in your schematic drawing.
In the original schematic it is placed after the 100k resistor and doesn't have contact with the 330pF cap; I think it's the same in the Black Sheep. Though I'm not 100% sure, this would mean there's an error in your schematic drawing.
Do you agree with this saying ?

I also re-read the article from Geofex on picking up the right transistors for a Fuzz Face. There's a simple explanation as of how to measure overall gain and leakage on PNP transistors, that can easily be adapted for NPN ones. I think I will test mine and see what I get. Here's the link for this article:
http://www.geofex.com/Article_Folders/ffselect.htm

I'm over the pond, in Switzerland actually, so as you say it won't be easy to send you the pedal just for trying purposes.

I've started drawing the schematic in Eagle to make my own layout too. I'm also thinking of changing the tone stack for the one of the Throbak OD that is really effective. The best way to go seems to take the tone stack out of the board, to try different options (modified BMP, Throbak OD, Marshall...).
As I don't have a breadboard (though I think I should get one), I will definitely socket all altered values and play with them and see what I can get from there.

[rocket8810]

Hmm. Well I took a look at the board again, and you are correct about the 47uF, it should be coming off the 10k resistor not the 330pF cap. I'll have to make the change. Ask good catch, I can't beleive I missed that.

As for the other things.
1- the sustain/gain control is essentially a voltage divide that limits the amount of signal going into the effect, and the caps switch is after it because it replaces the 1uF input cap.
2- if you replaced the tonestack for wheat you see in the throwback, you're basically changing the notch filter for a bandaxall, so you might need a recovery stage for the loss of output from the new tonestack.
3- I don't see the 10uF cap after the to stack. I see in the tonestack in the black sheep there's a 10nF to ground instead of 100nF in the original.

[V1nce69]

Thank you for your answer ! I can then go on with the drawing.

My bad for the capacitors' values, you're right, 10nF instead of 100nF in the tonestack of the Black Sheep.

The 1µF instead of a 10µF is the one that goes from Q2 emitter to ground.


Regarding the tonestack itself I will most certainly keep the original on the board and bypass it with a switch, kind of like in the Bee Baa, to try something else.

[rocket8810]

nope that's a 10uF. My hand writing looks like shit in pencil, so it might be hard to see the "0" in 10uF.

[V1nce69]

I'm done with schematic drawing (THX rockett8810 yours helped me a lot) and pcb layout. I haven't tested it yet, but it was drawn and verified with Eagle, so it should be OK.
The schematic is 100% stock. Gain, Tone and Vol are onboard pots, the rotary switch and 3PDT not.

Here are the files for those who are interested:

schematic for parts numbering and values

BAT Black Sheep - schematic

pcb - parts numbering & layout

BAT Black Sheep - pcb parts layout

pcb etching file

BAT Black Sheep - pcb etching file

[rocket8810]

nice work man. i've got the vero done, with all input caps, coupling caps, caps on BC on the transistors, and output cap socketed so i can mess with them to get it where i want. just finishing the enclosure so i can wire it all up. i decided to actually make an enclosure with graphics rather then just painting it, and it's the first etched enclosure i've done. the final clear is baking right now. hopefully i'll have it done tonight or early tomorrow.

[rocket8810]

ok, so i finished building mine and have a few things to report.

1 - the 47uF electrolytic cap to ground must have the positive leg at the junction of the 1k/10k/100k going to Q1, it not the whole pedal does not work. when i had it connected to the base of Q1 both the sustain and volume controlled the output, the selector switch didn't really do anything, and the tone didn't do anything.

2 - if you want to effect the amount of overall bass, play with the caps that connect to B & C of each transistor. the higher the value the more base. i found that lowering this cap too much on Q3 made it get very thin sounding, and upping the cap on Q2 too much made it very wooly even bringing it up to the original value of 4.7nF. I ended up changing the cap on Q2 to suit what i wanted to hear out of the effect.

3 - changing the input caps has a huge effect on the sweep of the tone knob. The lower the input cap the brighter the tone pot can get. seems obvious, but in my build it seems to be fairly drastic.

4 - upping the input, output, and coupling caps did nothing to increase the amount of bass. i went as high as 10uF for all of them, and it sounded the same as when it was 1uF. i did not go lower, as i've been looking at the original, which can get very nasally, and thin and all of these caps are 1uF. i'm sure that lowering all of these will help thin it out.

5 - transistor type and hfe have a massive roll in this thing. i tried damn near every transistor type i have, including a few NPN Ge transistors, and if the transistor isn't right there's this odd decay, farty, and i hear something almost metallic in the background. i found 3 types that sounded damn good to my ears: MPSA18, KT3102em, and ME4003(these are more compressed and buzzy).

[rocket8810]

I forgot to post the link to the layout over at tagboardeffects. http://guitar-fx-layouts.42897.x6.nabbl ... 19315.html

Also, figured I'ld post build pics.

[V1nce69]

I measured transistors' hfe (overall gain) on mine using R.G.Keen method given in his article on selecting transistors for Fuzz Face clone.
http://geofex.com/Article_Folders/ffselect.htm

Transistors are 2N5089. The overall gain reads as following:
Q1 436
Q2 406
Q3 410