Roland Double Beat fuzz section

[Freppo]

I made this layout for the fuzz section of the Roland AD-50 fuzz/wah - Verified!



Here's a video I found:



/ Fredrik

[Kinski]

Whoa! This thing sounds AMAZING!

Any chance I could build this using a 3-way TOGGLE switch instead of the ROTARY?
That way, I can stick to my obsession of fitting everything into a 1590A.

[Kinski]

Looking at other videos, I don't like the 3rd position. Its pretty thin and harsh. The other two positions sound huge.

So...I could just us an SPDT Toggle and get the first two tone position and ditch the 3rd, right?

Like this:

TOGGLE 2 to VOL 3
TOGGLE 1  to POSITION 1
TOGGLE 3 to POSITION 2.

This would work, right?

[Jopn]

Yep, based on what I'm seeing that would work.

[Kinski]

Great. Did you verify this yet?

[Freppo]

I built this one today. Works great and sounds awesome!
The only error was that I had the gain pot numberings wrong.

I have updated the layout, and I added info about each switch postition.

If you want to use a regular switch and skip the thin/harsh sounding positing you can omit C8 and R14 aswell. I tried to make the layout one row smaller without those components, but it was not possible.

The fat/dark switch position is alittle too dark IMO, so you might wanna socket and experiment with C7. I think a 4.7nf cap is better there.

cheers
/ Fredrik

[Freppo]

Oh, and btw. The fuzz pot should be a B50K or even a C50K for the best sweep. Forgot to change that on the layout. With a A50K most of the action comes at the end of the rotation. But it's not that picky, since the fuzz pot goes from fuzzy to more fuzzy.. :P

[mojo321]

I love the voiceover guy.   Holy Smokes.  That was crazy.  

[Jopn]

Stephen Hawking does the best gear reviews.

[Kinski]

Wow, just built this. Think I finally found a fuzz that truly competes for board space with my Foxx Tone Machine. This thing sounds fantastic! Huge amounts of fuzz on tap, and cleans up beautifully. This is what I always wished a Big Muff would sound/act like.

Used a three-way toggle, and did not wire up the "thin/bright" setting.

One question. I use single coils. With the amount of fuzz thing thing puts out, the pickups are humming like crazy. Is there a way to add a GATE to this circuit?

I know there is a Big Muff GATE MOD. Something like this would be very useful:
"Noise gate mod: This mod will quieten the Muff while not playing, thus a noise gate. To do this, add a 100k trimpot (wired as a variable resistor) parallel to the 100k to ground of the second gain stage (R14). The trimpot can be adjusted to taste to get the max noise gate effect."

Thanks Freppo!

[Kinski]

Also, I think this pedal would benefit from having a pot at the input of the pedal. Since it cleans up so well, there is a wide range of low gain dirt to be found. Really clear and smooth, not dark and crackly like a lot of other fuzz circuits. The pre-gain pot would let you "set and forget" the lower gain ranges. I'll be doing this for sure.

[Freppo]

Nice! Please share a picture of your finished pedal when you're done :)

I have no idea how to add a gate.. you could probably starve/misbias one of the transistors to achive gated fuzz, but it would probably make it sound sputtery and loose sustain.. I would put the circuit on a breadboard and experiment, start with R7.

Nice idea about the pre-trimmer. I will try that :)
cheers / Fredrik

[Kinski]

I have not boxed it up yet. Will probably be a few days till I get a chance to do that. But I'll post it when I do.

[alltrax74]

Hey Freppo, I built this this morning, thanks for the layout !

However it doesn't sound as nice as the vid, quite gated and a bit broken.
I used PN2222A as I currently don't have 2N2222A, that may be the problem
Could you or Kinski post your hfe for q1-q3 ?
I used a C50k pot for the fuzz, but it's not doing much from CCW to CC, i can hear the gain increasing but not that much.
I used a spdt switch and did not wire the thin position, and i socketed C7, i agree that the fat position is a bit too dark, i'll have to try a lower value
Here is a pic, plugged in my test box

[Freppo]

hey :)

That doesn't sound right. Check the usual suspects and the orientation of the transistors. Sometimes the same type transistors has different pinout depending on manfacturer. The layout is Q1: CBE (from top to bottom), Q2: EBC and Q3: CBE. Other then that i'm afraid I can't be of help. Good luck, I hope you find the problem!

The fuzz pot is a bit wierd as the original.. it goes from very fuzzy to even more fuzz, so it doesn't have a wide range and never cleans up with the fuzzpot, so it should probably be that way :P

[alltrax74]

The trannies have the same pinout, i checked that before
ok for the fuzz pot, so it's normal
I think my build is ok, it sounds like a fuzz, but not like the vid
I'll get some 2n2222a with my next Tayda order to see if it changes something, and i'm still interested by your hfes :)
Anyway thanks for sharing all those layouts

[Kinski]

Hi alltrax74,

Mine works great and sounds just like the video. I just randomly picked some 2n2222a trans from a large bag and dropped them in. I didn't even check hfes. Hope you get it working.

[Neil mcNasty]

This si one of the coolest fuzzes I have built in a long time.
There are quite a few mods that I would recomend.
Instead of removing the posision 2 tone option that sounds thin, I simply doubled the cap value, and it became very usable.
I also adjusted the dark setting (nr.3) by lowering both the 6.8nf caps to 4.7nf, and it turned out much better.
I also used a 6-way switch and added the 3 extra tone options found here: http://www.guitarscanada.com/showthread.php?53902-Roland-Double-Beat
All of them sounds better then the stock options. Higly recomended.

In addition to these mods I also added a 500k log pot to the input as a pre-gain, that gave me a much wider range of tones.
And finally I replaced R7 with 250k linear pot, with a 33k resistor going from the voltage track to lug 1 of the pot, then wiring lug 2 from the pot to the transistor's collector, and then I had a pinch/gate control. Be aware that you will loose much of the sustain when the gating kicks in, but it sounds quite cool and removes all of the noise issue. Specially the spot where the gate starts to kick in is very nice. This way you get something that sounds a bit like the pinch/gate funtion on the ZVex pedals.

Cheers!

[Freppo]

Awesome! Thanks for the mod suggestions Neil, I'll definitly try that pinch/gate/starve one :)

cheers
/ Freppo

[Neil mcNasty]

After some experimenting with the gate/pinch feature, I have desided to also add a booster in front of the circuit. That way I am able to push it harder when the gating becomes extreme and I can get evn more crazyness out of it. I used de Escobedo Duende JFet booster and is really pleased with the result.
I also tried to raise the cap of the thin setting to 1nf (and raised the resistor to 220k) and it sounds amazing.
Now the dark setting is the one I do not like very much, so I am considering changing it back to my first adjustment, and have a go at the dark setting, raising the output cap to 1nf and lowering the cap going to ground (or maybe removing it) to mak that setting more usefull.
Anyway: I have made a vero with all the changes/extra mods + added the booster, and I'll post it here as soon as I have built/verified it tonight.

Thanks a lot for the layout and bringing my attention to this circuit Freppo.
This is the most fun I have had since starting building pedals.
This one rules! Love it to death!

Neil