Tufnel Distortion

[dano12]

In a recent quest to make the loudest rudest distortion as simply as possible I came back to my favorite chip ever: the 386.

Here are two of them cascaded. No silly tone knob because Nigel would have just sneered at that. Two gain controls, on volume knob, and loads of sustain.



And yes, it does go to 11.

[John Lyons]

Nigel would be proud.
Can you describe the sound (other than loud  )

john

[dschwartz]

hahaha this is sooo cool!!

[tcobretti]

Dude, the two gain controls is total Spinal Tap, cause that way it can get even louder.

[Zben3129]

I'd imagine this one could induce some good eardrum distortion aswell 


Zach

[John Lyons]

...when you need the extra push over the cliff.

[FiveseveN]

I love 386 distortions but I must ask...
1. can the chips take it (i.e. won't burn out)?
2. what does it sound like? Do you get anything other than noise?

[dano12]

The 386 chips are fine as long as you run them at their rated voltage. Of course the output is quite loud so I'll have to measure it before I actually turn it up to 11.

It sounds really really good. Great distortion with loads of sustain. Both U1 and U2 are stabilized using standard datasheet tricks. R4 and C7 tame the output of U1 a bit to keep it from oscillating.

Even on the breadboard it is *fairly* quiet, so I would expect that a clean build in an enclosure would yield a very workable pedal.

Tonight I'll add a switch to go between the existing C9 part and a 220uf electro. The idea being that with that switch I can go from distortion pedal to double ruby amp ...

[Mark Hammer]

I hasten to remind you that the zone where the gain is applied in the 386 can be determined simply by sticking a cap in series with the 1k gain pot.  Normally, we are used to the pin 1-8 path being bridged by either a pot, or a fixed resistor, or a pot and large value cap (10uf).  replace that cap with a smaller value (e.g., .047uf or .01uf) and the gain is applied only in the mids or upper frequencies.  It works a bit like emitter caps.

[dano12]

I hasten to remind you that the zone where the gain is applied in the 386 can be determined simply by sticking a cap in series with the 1k gain pot.  Normally, we are used to the pin 1-8 path being bridged by either a pot, or a fixed resistor, or a pot and large value cap (10uf).  replace that cap with a smaller value (e.g., .047uf or .01uf) and the gain is applied only in the mids or upper frequencies.  It works a bit like emitter caps.

In previous builds, I added tone stacks after the 386, such as in Aron's 'super' version of the Smash Drive. I also breadboarded the krank distortion pedal that uses a similar tone stack at the end, albeit a poor one.  There is also the trick of inserting a filter between the output of the chip and feedback pin 1 (ala the Bass Boost idea in the datasheet example).

In the end, tone shaping seemed to be so not part of the Tufnel philosophy.

Good point nonetheless!

[BDuguay]

Once one has built this, are they allowed to let anyone look at, or even touch it?
B.

[dano12]

Once one has built this, are they allowed to let anyone look at, or even touch it?
B.

none more black

[alex frias]

Do I need a special pot that goes to "11" ?

[hoopshot]

I think you need to change the pots to 1K1, so that they can go to 11. 

[dschwartz]

if you want a tonestack i strongly recommend a baxandall type..they just rock!!

[John Lyons]

...wos rong wif sexy?

[Filament]

I often find myself wanting to play a bit, set my guitar down and go for a bite but still have my guitar sustain while I'm away.  Is that possible with this pedal?  If so, I'll take two and run them in series.  That way, it'll go to 22 

[newfish]

Will there be a VU meter on the box?  I think one might be needed to show just how loud '11' is.

Maybe you could play 'Stonehenge' on it with the dancing people.  That way it would also go to 'Elven'.   

...sorry, really really sorry...

[Mark Hammer]

Well if there are only two knobs, one should be labelled Love, and the other should be labelled Pump.  The player has to supply the licks.

[BDuguay]

I can see this thread going in a different direction really quick....
You could build a special Artie Fufkin model and label the controls 'Kick' and 'My A$$'.
B.
"There's a fine line between clever and stupid"