Dunlop - Eric Johnson Signature Fuzz Face EJF1

TheLemon · Post by **TheLemon** » 02 Oct 2012, 22:30

okgb wrote:Is there a summary of what parts make the EJ circuit different ? , not many parts so it can't be much ?

Here you go! https://i1199.photobucket.com/albums/aa ... ences1.jpg

rugeb · Post by **rugeb** » 04 Oct 2012, 18:00

TheLemon wrote:
okgb wrote:Is there a summary of what parts make the EJ circuit different ? , not many parts so it can't be much ?
Here you go! https://i1199.photobucket.com/albums/aa ... ences1.jpg

The original transistors: BC183 and BC183C :

sinner · Post by **sinner** » 04 Oct 2012, 18:08

Dudes, WTF?

Beedotman traced this, he measured transistor gains and even checked to what value trimpot on Q2 collector was

Check the page 14

DrNomis · Post by **DrNomis** » 16 Oct 2012, 03:49

Guess what?, I just got this home after paying the rest of the money off this morning (I had to put $50.00 on deposit before the guys at Cool Bananas, a music shop just up the road from where I live, could order it for me), yes it's my new Jim Dunlop Fuzz Face, will post some more pics in the workbench section later on as I'm low on internet credit......

jalmonsalmon · Post by **jalmonsalmon** » 20 Jul 2013, 16:45

Interesting discussion here!

Hey, where does one find those big yellow AD .01 uF film capacitors, chicklet type?
I have done searches for those but nada... oh and would a vishay Roederstein film cap work as well?

jalmonsalmon · Post by **jalmonsalmon** » 23 Jul 2013, 13:53

Quick question but are there differences in gains from the 183L and 183LC ?

DrNomis · Post by **DrNomis** » 23 Jul 2013, 14:39

jalmonsalmon wrote:Quick question but are there differences in gains from the 183L and 183LC ?

The letters after the numbers basically indicate different Hfe (current gain) brackets.....

jalmonsalmon · Post by **jalmonsalmon** » 23 Jul 2013, 18:39

Ah I found some data gains
Mat Struct Pc Ucb Uce Ueb Ic Tj Ft Cc, pF Hfe Caps
BC183C Si NPN 0.3 45 30 6 0.2 150 150 5 450 TO226
BC183LC Si NPN 0.3 45 30 5 0.2 150 150 5 450 TO926
BC183L Si NPN 0.3 45 30 5 0.2 150 150 5 120 TO92
BC182L Si NPN 0.3 60 50 5 0.2 150 150 5 120 TO92

Looks like I don't need those LC's... For Q1 I need the normal BC183L and maybe will try the BC182L since I have some of those already

jalmonsalmon · Post by **jalmonsalmon** » 23 Jul 2013, 18:56

Not meaning to spam this thread but I love the EJ fuzz and I have 10 x bc183c's 10x bc182l's - (all fairchilds) and a lot of 10 x bc183l's ( not fairchilds) coming to try out for this fuzz just to cover all my bases...
I can kind of tell how the cold bias effects the sound of this pedal along with the other tweaks and am hoping the non fairchild bc183l will work out with proper gains. Such a simple circuit with so many options to tweak

DrNomis · Post by **DrNomis** » 23 Jul 2013, 19:12

jalmonsalmon wrote:Not meaning to spam this thread but I love the EJ fuzz and I have 10 x bc183c's 10x bc182l's - (all fairchilds) and a lot of 10 x bc183l's ( not fairchilds) coming to try out for this fuzz just to cover all my bases...
I can kind of tell how the cold bias effects the sound of this pedal along with the other tweaks and am hoping the non fairchild bc183l will work out with proper gains. Such a simple circuit with so many options to tweak

Yep, the sound you get is going to be heavily dependant on where you set the biasing point for Q2, I found that if you start with the biasing set so that there's very little voltage on Q2's collector, it'll sound very sputtery and gated, as the voltage on Q2 increases, the sound gradually gets smoother, you'll also notice that at low Q2 collector voltage setting the timbre (a French word meaning Tone Colour)is thin and reedy, as you increase the Q2 collector voltage the timbre starts to sound more like a square wave, another thing you'll notice is that the timbre is affected by how hard or soft you pick (touch sensitivity), too.....

rugeb · Post by **rugeb** » 28 Jul 2013, 18:14

jalmonsalmon wrote:Interesting discussion here!

Hey, where does one find those big yellow AD .01 uF film capacitors, chicklet type?
I have done searches for those but nada... oh and would a vishay Roederstein film cap work as well?

The caps are PHILIPS, for sale here: http://www.ebay.es/itm/1-PC-Philips-341 ... 3c7&_uhb=1
·

jalmonsalmon · Post by **jalmonsalmon** » 29 Jul 2013, 23:45

rugeb wrote:
jalmonsalmon wrote:Interesting discussion here!

Hey, where does one find those big yellow AD .01 uF film capacitors, chicklet type?
I have done searches for those but nada... oh and would a vishay Roederstein film cap work as well?
The caps are PHILIPS, for sale here: http://www.ebay.es/itm/1-PC-Philips-341 ... 3c7&_uhb=1
·

Yow! No thanks on those.... hahaha
I actually have one of these coming in the mail soon from here and I am only getting one just because they look cool...
https://www.ebay.com/itm/NOS-VINTAGE-DA ... 3383b15b23

Mouseydung · Post by **Mouseydung** » 07 Aug 2014, 13:15

Hello All!

Thanks for participating in such an informative forum. It's been really educational to learn how to build my own pedals based on all your contributions! I read every single post here, all 18 pages, and put together one of these EJ fuzzes by following the traces and specs. I don't have an original EJ fuzz with which to make an A-B comparison, but I'm experiencing a few problems and so I'm not so sure I've got it right. If I have, then maybe I'm just looking to improve on the design, haha.

For my build, I used metal film resistors, and polyester and tantalum caps. I couldn't find any BC183s with the right specs, so I've used BC547, BC548 and BC549 transistors that were close to the magical hFE values of 217 and 547.

I used a 500K for the volume pot. I combined R4 and VR1 into a single 10K trim pot and set it at about 8.27K, then readjusted it to ensure that about 3.17 volts was being supplied to Q2. Then I even tried readjusting to find a sweet spot according to my ears.

Here are my issues:
1. The tone. The whole point of this fuzz seems to be lost, when all I've ended up with is really thin-sounding fuzz, with no body and warmth produced by EJ himself or some of the pedal demos out there. I swapped C5 for a 100pF cap to tame down Q2, and even placed another 100pF cap in the unused C4 position to tame Q1. This helped, but it's still to thin for my taste.

2. The fuzz knob. When full, it's a bit too much fuzz, but not to the point of oscillation. I dial it down to 60%, starts sputtering and some of the weaker signals don't get even through. When it's down to below 50%, the fuzz pedal is basically turned off.

3. Hum. I've got everything grounded as it should be. I do realize that pretty much all fuzzes come with some amount of hum, but man, when I put a wah pedal in front of the signal, it hums so loudly I can't appreciate what I'm playing anymore.

Could it be that I've got something out of balance in the circuitry or that I've fried some of the components by accident?

IDK... I find that when I set the fuzz knob on about 90% and my telecaster's tone to about 80%, and set the volume at no higher than 90%, I've got the perfect fuzz. But in a live situation, having to make multiple adjustments whenever you engage/disengage a pedal, is just not cool!

Is there any way I can mimic the settings on my guitar by adding a tone control and input volume limiter somewhere? Any suggestions for how to eliminate the hum?

Looking forward to your responses!

Chris Brown · Post by **Chris Brown** » 07 Aug 2014, 17:13

Mouseydung wrote:Hello All!

Thanks for participating in such an informative forum. It's been really educational to learn how to build my own pedals based on all your contributions! I read every single post here, all 18 pages, and put together one of these EJ fuzzes by following the traces and specs. I don't have an original EJ fuzz with which to make an A-B comparison, but I'm experiencing a few problems and so I'm not so sure I've got it right. If I have, then maybe I'm just looking to improve on the design, haha.

For my build, I used metal film resistors, and polyester and tantalum caps. I couldn't find any BC183s with the right specs, so I've used BC547, BC548 and BC549 transistors that were close to the magical hFE values of 217 and 547. I used a 500K for the volume pot. I combined R4 and VR1 into a single 10K trim pot and set it at about 8.27K, then readjusted it to ensure that about 3.17 volts was being supplied to Q2. Then I even tried readjusting to find a sweet spot according to my ears.

Here are my issues:
1. The tone. The whole point of this fuzz seems to be lost, when all I've ended up with is really thin-sounding fuzz, with no body and warmth produced by EJ himself or some of the pedal demos out there. I swapped C5 for a 100pF cap to tame down Q2, and even placed another 100pF cap in the unused C4 position to tame Q1. This helped, but it's still to thin for my taste.

2. The fuzz knob. When full, it's a bit too much fuzz, but not to the point of oscillation. I dial it down to 60%, starts sputtering and some of the weaker signals don't get even through. When it's down to below 50%, the fuzz pedal is basically turned off.

3. Hum. I've got everything grounded as it should be. I do realize that pretty much all fuzzes come with some amount of hum, but man, when I put a wah pedal in front of the signal, it hums so loudly I can't appreciate what I'm playing anymore.

Could it be that I've got something out of balance in the circuitry or that I've fried some of the components by accident?

IDK... I find that when I set the fuzz knob on about 90% and my telecaster's tone to about 80%, and set the volume at no higher than 90%, I've got the perfect fuzz. But in a live situation, having to make multiple adjustments whenever you engage/disengage a pedal, is just not cool!

Is there any way I can mimic the settings on my guitar by adding a tone control and input volume limiter somewhere? Any suggestions for how to eliminate the hum?

Looking forward to your responses!

From my experience the bc183s have a sound that nothing else gets... Sometimes they show up on the bay and also smallbear usually has some.

For the hum I would check my solder... maybe look for ground loops. If you use an unbuffered wah it's going to sound pretty wild no matter what... think hendrix isle of wight or rainbow bridge.

For the tone... try running the fuzz control all the way up and then adjusting the guitar knobs... the ej lead tone comes from fuzz all the way up + strat bridge pickup with the tone rolled back some. Rhythm tones come from fuzz all the way up and guitar volume rolled back. Check out I go through a lot of these settings. Also the amp has a lot to do with how a fuzz face sounds... what are you using?

Post your voltages for each leg of both transistors... that will be a good starting point... .also if you post some close up shots of your build maybe someone smarter than me can look and see what the problem is.

Best, CB

Mouseydung · Post by **Mouseydung** » 07 Aug 2014, 18:32

Chris Brown wrote: From my experience the bc183s have a sound that nothing else gets... Sometimes they show up on the bay and also smallbear usually has some.

I'll definitely try to hunt some of these down. I managed to find some BC183Ls, but they didn't measure up, so I never bothered to stick them into the pedal. Maybe I ought to.

Chris Brown wrote: For the hum I would check my solder... maybe look for ground loops. If you use an unbuffered wah it's going to sound pretty wild no matter what... think hendrix isle of wight or rainbow bridge.

If by ground loops you mean differences in potential at different earthed points, then we could rule that out, because all the ground points are pretty much daisy-chained.

Chris Brown wrote: For the tone... try running the fuzz control all the way up and then adjusting the guitar knobs... the ej lead tone comes from fuzz all the way up + strat bridge pickup with the tone rolled back some. Rhythm tones come from fuzz all the way up and guitar volume rolled back. Check out I go through a lot of these settings. Also the amp has a lot to do with how a fuzz face sounds... what are you using?

Kudos! I just checked out your demo once more and you have a far warmer, creamier tone than what I ended up with. As close as I've tried to follow the details in this thread, your build and mine have somehow turned out quite differently.

Maybe the EJ fuzz is supposed to be somewhat wild by design, but I would like for it not to have such a piercing tone to start with. Obviously, I'm okay with some adjusting in live situations, but as it is now, it's unpleasant the moment I step on it. With my volume and tone full, it's way too fuzzy and horribly sharp by default -- nothing like yours.
As far as amps, I mainly use various Mesa Boogies: 2-90; Mark I (essentially a Bassman circuit on one channel?); Mini-rectifier with bass-rich tubes. I have the latter set to sound warm, but with the mids cut somewhat so as not to be too annoyingly Meas-Boogie-ish.

Chris Brown wrote: Post your voltages for each leg of both transistors... that will be a good starting point... .also if you post some close up shots of your build maybe someone smarter than me can look and see what the problem is.

I'll try to get around to doing that later this evening. I realize this is not supposed to be a sandbox forum, but I'm just wondering where I might have gone wrong to end up with my pedal so un-EJ-like.

Chris Brown · Post by **Chris Brown** » 07 Aug 2014, 21:22

Your amp is definitely not the problem.

The ground loop problem is more of an amp thing where current differs vastly in different parts of the circuit... probably not an issue now that I really think about the circuit.

Try your bc183ls... i think they have a different pinout so check a datasheet... I've built a lot of fuzz with the bc183x and no matter what the gain range is they always seem to have a "rubbery" quality that other transistors are missing.

There is always the possibility that one of your caps is defective and measuring way lower than it should... you can also try upping the taming cap between the b-c of q2... this will cut some harshness but it can also muddy up the fuzz if you take it too far.

Just keep messing with it and you'll get the sound.

Best, CB

Mouseydung · Post by **Mouseydung** » 08 Aug 2014, 16:26

Chris Brown wrote:Your amp is definitely not the problem.
Try your bc183ls... i think they have a different pinout so check a datasheet... I've built a lot of fuzz with the bc183x and no matter what the gain range is they always seem to have a "rubbery" quality that other transistors are missing.

Wow. You were absolutely right. I have most of my components mounted on sockets, so I pulled out each cap and tested them. The pedal still sounded like s**t. So I swapped the BC547/8/9s for two BC183s and it made a helluva lot of difference. I'm still not there yet, but the pedal has now been transformed into a musical instrument. No more excessive fuzz, no more unbearable hum, even with a wah pedal in front of the signal.

Chris Brown wrote:Your amp is definitely not the problem. Just keep messing with it and you'll get the sound.

The reason I didn't use the BC183Ls to start with, is that they were all within the 475 - 515 hFE range. I figured it was important to keep the ratio of about 2.5 between Q1 and Q2, so I resorted to using alternatives. I'd seen some of these BC54X transistors in other fuzzes and thought it was all cool beans. I can safely conclude that matching the hFE values alone won't do it -- the type of transistor is crucial, at least in this case.

Another interesting development with the BC183s in place, is that the sweet spot for Q2 is to bias at about 5 volts -- not 3.17 volts. At this voltage, the fuzz is weakened to the point that the tone lacks body. Any higher than 6 volts and I get the blunt-buzzsaw effect starts to take hold. So somewhere between 4.5 and 6 volts, the strings "twang" right and this is some scope for varied expression through picking/muting techniques.

I'm guessing this voltage setting is necessary because the ration between Q1 and Q2 is almost 1:1.

In any case, I'll be hunting for some BC183s!

Thanks for now! Will keep you'all posted if I manage to get this working any better

Skreddy · Post by **Skreddy** » 08 Aug 2014, 19:23

I have some NOS trannies in a bag. I think I might have both types to make proper Q1 and Q2's. When I have a minute of free time (fucking crazy busy here of late), I'll test up a few and make sure. No doubt some noise screening is called for in addition to the Hfe sorting. Sorry to tease, but I'll get back to this when I can.

sinner · Post by **sinner** » 08 Aug 2014, 22:15

500hfe range bc183l's?

Man, u r lucky. Mine tests 250max.

Mouseydung · Post by **Mouseydung** » 10 Aug 2014, 01:38

This is probably a stupid question, but here goes:

At the top of page 18 of this thread, there is a schematic posted by TheLemon, dated Oct 3, 2012. Right below it is a closeup pic of the BC183 transistors. Am I correct to assume that all the schematics posted here were traced from the front/back sides of the PCBs of the same one or two EJ fuzzes volunteered as samples? If so, and if BC183s are supposed to have different C-B-E pin configurations (as mine certainly do), wouldn't that make the schematics here (including those posed by Zokk and bedotman on May 19, 2012) incorrect?

Dunlop - Eric Johnson Signature Fuzz Face EJF1 [traced]