New "Tornado" sound sample ....

[gaussmarkov]

hey all,

I live by the 50:50 rule. I try to make a trace and the spaces between them roughly equal. With the usual 2.5mm grid spacing, that makes 1.25mil perfect for my tastes.

That's roughly .05" so I guess .04" looks pretty good.
Jimbo

I usually go .04 or .05 depending. Soldering and etching larger pads and traces is so much easier.
Cool!
John

i increased the trace width to .04" following everyone's suggestions.  thanks!

GM, great stuff  ... many many thanks for making a whole project file from this

You're a true "Gent"   

thanks for the compliment, Marty.  it's my pleasure.  as everyone else has said, thanks go especially to you for sharing your research.

cheers, gm 

[Nashtir]

Marty this pedal sounds awesome!!I can't wait to build it!Last exams at university and I'll get myself in building this pedal!

[MartyMart]

Marty this pedal sounds awesome!!I can't wait to build it!Last exams at university and I'll get myself in building this pedal!

Thanks Nashtir
Yup, it does have it's "own voice" and quite an amp "like" response.
I hope that your's lives up to the mp3  !!


MM,

[Ed G.]

Sounds freakin' awesome! Love those tones, very convincingly amp-like! Sounds like you can really dig in, if you know what I mean.
Just watch yourself, keep an eye out for those who would use your design for their own profits.

[MartyMart]

Sounds freakin' awesome! Love those tones, very convincingly amp-like! Sounds like you can really dig in, if you know what I mean.
Just watch yourself, keep an eye out for those who would use your design for their own profits.

Thanks Ed, that means a LOT coming from you 
And thanks for the BSIAB TC .... which I pretty much "stole" !
Yes, the "diggin in" works a treat, I'm pleased as punch with the response of this thing
I just wish that i knew "technically" .... what I've done 

Well, it's up there now so it will find a "place in the universe" !
No biggie, I can't see anyone commercialy trying to bias all those Jfets !! and they wouldn't
be able to afford the trimpots 
I'm not in a position to go commercial with it anyway, but wouldn't mind selling boards or a
kit perhaps.

Marty.

[gaussmarkov]

I'm not in a position to go commercial with it anyway, but wouldn't mind selling boards or a
kit perhaps.

Marty, fwiw, i would love to see that work out for you.  you are most welcome to use
any layout of mine. 

all the best, gm

[brett]

Holy freaking cow!!
This has totally ruined my plans for retiring from making distortion boxes.
The decay is exceptional.  There seems to be a tonal "bloom" on the decay which I can't find in the schematic, but has to be in there somewhere.

Just a couple of suggestions:
the big muff style tone section is always susceptible to changes that depend on the output impedance of the previous stage.  That trimmer on the previous JFET, and the transconductance of the JFET will set the output impedance.  This means that individual JFETs will sound slightly different, and different JFETs may sound completely different (I *think* that an MPF102 will lose a lot of treble, for example).  So it will be important to only use a J201 in Q6.

Similarly, the big muff tone section is sensitive to the load, and the tone might change if driving loads less than about 100k (ie equal to, or less than the output pot)  Everything should be 100k and over these days, but older gear like old solid state amps might be less.  An output buffer would fix it (but it will only occur rarely, so maybe it isn't really a problem?)
cheers
cheers

[MartyMart]

I'm not in a position to go commercial with it anyway, but wouldn't mind selling boards or a
kit perhaps.

Marty, fwiw, i would love to see that work out for you.  you are most welcome to use
any layout of mine. 

all the best, gm

As I've said before , you're a "True Gent"  
Offer much appreciated .
MM.

[MartyMart]

Brett, thanks for the info, it seems the Tornado has had some more interest today !
About Q6, my first thought was to have it as a source "follower" stage rather than coming off the
drain for output, but I wasn't sure what this would do to the BMPI style tone stack, do you think this
would improve/damage the impedance here ?
Or perhaps setup it's bias with a direct 9v to drain and have a 10-15k off source - output here also
..... hmmm now I want to build another one and "tinker"   

MM

BTW - I have no clue as to what I've done here, but it sounds awesome 

[brett]

Hi Marty
IF you feel that you can "lose" about 2 dB of gain, then a J201 source-follower would be the way to go with Q6. 
Check out the source-follower used to drive the tone section in the Dr Boogie.  That's a good system (the gate is connected directly to the drain of the previous stage, so it is biased just right).  Maybe lower the 10k source resistor to 3.3k or 2.4k for optimum audio results (but at a cost of an extra 1 to 2 mA of power consumption).
cheers

[Steben]

Have you seen this marty? http://www.aikenamps.com/    >Tech Info > Advanced > What is miller capacitance
Explains the effect of high value series resistors on Tube and FET inputs in conjunction with the pf cap (with FETs)

Good stuff there and on the other pages. Makes my brain hurt!

John

Aha!
That's why loud fuzzes can sound so smooth when their level pots are large!
A cap over there,... Another simulateable secret of the magical tube amps in conjunction with stompboxes!

[Khas Evets]

It sounds amazing. I'm a little perplexed over the dual signal paths. It appears that one signal goes through an additional three gain stages, and (I think) inverts phase each time. That means you're mixing two out of phase signals (one more distorted than the other). I would think this would produce a strange looking wave, but it sounds very musical. I must be missing something.

[brett]

Hi

Explains the effect of high value series resistors on Tube and FET inputs in conjunction with the pf cap (with FETs)

In the Tornado there's also filters applied with gase-source caps.  No doubt they play a big role.  Take Q2.  If I've got it right, with the pot at 100% the input resistance to Q2 is 680k||1M +330k = about 500k (not allowing for the effect of the bypass cap).  But all that is || with the 180k resistor, so the end result is about 150k (guess).  The rolloff freq for 150k and 120pF is a bit over 8kHz - quite a low value in comparison to most circuits (except the filter in the Rat, the gain stages in the big muff and a coupla other sweet-sounding things).

cheers

[MartyMart]

What do you need over 8Khz in a guitar sound ?
Most amps do go up above there ....

...... good thing too !

[Victor]

Really nice sound. My next build (my Phase 90 will wait a little longer)

About the circuit: is it possible to apply that "cross-feeding paralleled signal" (just made up that horrible name ) into other circuits, like Dr. Boogie, for example? I want that "amp-like" sound in all my pedals lol! Can you explain in more technical words the behavior of that signal jumping a part of the circuit and feeding another part, in addition with the signal from the other part of the circuit (i dont know if you can understand me :S)

[MartyMart]

A feedback path is not new, it's used in the FuzzFace !
I've seen it used quite a few times, I'm not sure about the "phase" relationship as mentioned
just above, however without this path the circuit is different and a more conventional distortion.
You can try something similar with other circuits, suck 'n see !
As far as I can tell in this instance, some clean signal gets mixed in down the circuit from this
link and causes better pick dynamics and a certain "spank" to the tone, rather like an amps
"speaker spank" response.
You dont normally get this effect without an amp and a speaker being pushed quite hard

MM.