"Vox flavoured" sixteen overdrive

[blustrat]

Hello everybody,
this is my first post here, apologies for my english...I am italian!

One of my diy favorites pedals is the Erik Hansen's "sixteen", the overdrive based on the ROG Fetzer Valve (i am a big fan of you guys!!!!!!) tweaked to be a Marshall like sounding pedal. What i decided to do is a Vox version of this pedal, nothing new under the sun ok...but i play in a Beatles early days cover band and need a booster, so... the Fetzer30 is born!
This is the schem:
http://putfile.com/pic.php?pic=4/10313115941.gif&s=x402

Infinite thanks to Erik Hansen and the guys at Runoffgroove.

http://www.runoffgroove.com
http://diy.erikhansen.net

[PenPen]

Not seeing a schem. I'd like to, the project sounds really cool and I'm a fan of Vox amps.

If you're having troubles posting the image due to hosting problems, PM me and I can put it in my gallery so it can be displayed.

[vanhansen]

I can see the image here.  Very nice.

Just an FYI, the Sixteen OD is based more off the JCM800 Emulation than the Fetzer Valve but the first part of the Sixteen OD is the Marsha Valve which was inspired by the Fetzer Valve.  I guess there's a "grandparent" connection there anyway. 

Edit: Well, I did see the image earlier but not now after refreshing my cache.

[R.G.]

Just a quick question - is there a set of things you can write down that makes it sound like a Vox, or did you just tinker until it was subjectively right to your ear?

[blustrat]

If you're having troubles posting the image due to hosting problems, PM me and I can put it in my gallery so it can be displayed.

Yes there is some problems with the Italian web hosting so the image is not visible, thanks for help. Now i move it to Putfile and the link works well.

Just an FYI, the Sixteen OD is based more off the JCM800 Emulation than the Fetzer Valve but the first part of the Sixteen OD is the Marsha Valve which was inspired by the Fetzer Valve.  I guess there's a "grandparent" connection there anyway. 

Excuse me for a little confusion Erik, thanks for clarify that.
O.T. I am glad you like the clips of the 16OD i sent to you.

Just a quick question - is there a set of things you can write down that makes it sound like a Vox, or did you just tinker until it was subjectively right to your ear?

Thanks for the good question Mr. Keen, what can i say about...my attempt was to tweak a two stages fetzer to obtain smooth overdrive with some sparkle high end and tight lows. The first stage is the same of ROG English channel that replicates the AC30 input, just a fetzer valve with more gain. The second stage was inspired by Erik's 16OD with the 1M res to keep the bias of Q2 stable. The low pass filter at the output was also inspired by ROG English channel, it is necessary to cut out some stinging highs, i use a simple cap\res combo to do that instead of the dual low pass filter of the e. c.
With a strat through a Fender solid state amp it sounds very similar to the Beatles "Nowhere man" George Harrison chords solo.
Thanks everybody, apologies for my bad English, have a good Easter.

[trevize]

e bravo blustrat!

do you have samples for this circuit?
I'd really would like to hear how it sounds.

[blustrat]

Ciao trevize! Ci si ritrova su lidi stranieri eh? 
Be patience, samples coming out soon!

[MartyMart]

This sounds very nice ! ( I'm a Jfet OD fan of course )
First "build" in about five weeks, I've been very busy working    !!
I made a few interesting subs, as I found the bright setting too much for my
taste.
Caps off both Jfets are now 10n's
Input resistor is a 47k
Bypass resistors are both 1k2's ( all I had )
J201 in first Q and MPF102 in second Q.
220pf cap in parallel with a 470k to the gain pot.
100 k volume pot.

MM.

[trevize]

I was thinking about making a pcb layout for this.

It seems a very simple overdrive structure and seems very easy to
play with (i've built an overdrive very similar to this but without the lp filter).

I'm not using very much the overdrive i made on stage because of misbiasing problems that
every fet circuit seems to have (if you change power supply or your battery is dying etc.)

why not integrate a voltage regulator in fet overdrive/emulators?
i suppose that a 78l05 and 10k trimmers would do the job.

[blustrat]

I am very glad you like it Marty. Yes, 470p cap makes it sound very bright with single coils, but that was the sound i am looking for, it really cuts through the mix with a good sharp attack. I am a jfet overdrive fan also, i think it sounds much "organic" than op. I think your version is much similar to Erik's 16od due to the .01uf caps, it really makes the pedal growl. I would like to hear how MPF102 sounds on this kind of circuit, but here in Italy it's hard to find, all i have are j201s from ebay  .
Awesome idea trevize, pcb layout with voltage reg is welcome. Zener diodes on fets drain could be an easy solution?

[blustrat]

I tried differents caps to better balance the sound between the bright and normal positions, the 470pf is now .001uf and the 47n is now .0047uf, this makes the pedal usable with my tele also, before this change it has too much piercing treble in bright position and too much muddy lows in normal position with this guitar.
I also add a dual low pass filter at the end of the circuit, to my ear it makes the sound more balanced.
I tried a bleed cap to the gain pot, as Marty does, it help to maintain brightness as the gain decrease.
enjoy
http://putfile.com/pic.php?pic=4/10809140887.gif&s=x11