Sweet16 Build Report - It's, uh, SWEET!!

[mydementia]

Hi guys.
It seems that I'm on a mission to build all the Doug Hammond circuits that are now openly available.  I saw that Bucksears is working on a new Sweet16 PCB based on WGTP's modified circuit... somehow I missed this circuit all these years... so I built one this morning.  I used RG's old layout from geofex.com:
http://www.geofex.com/PCB_layouts/Layouts/sthart.pdf

I used the GGG charge pump circuit (http://www.generalguitargadgets.com/pdf/ggg_ps_cp17_lo.pdf) to get ~17V (came out about 16.8V from my test wall wart putting out 9.1V).  After several auditions, I settled on a 10nF treb cut cap (Cx).  Without Cx, the circuit tends toward wild oscillations at max "Tone" and "Drive".  This cap makes a HUGE difference in the overall tone (after an audition with no Cx, I tried a 0.15uF - darkened it up WAY too much - then I tried a 1nF... only tamed the wild oscillations a little - the 10nF cap was my winner - your ears might like something different).  How does it sound?  Friggin awesome.  Sustain FOR EVER!!  At min Tone, it's dark but retains the same distortion characteristics.  At max Tone, it's just a shred-machine.  Tight palm-mute chug, great heavy tone.  Sounded good in my ss test amp (Ibanez TB15D) and in my Carvin Vintage16 tube amp. 

Complaint?  Only negative I hear in this circuit is the background hiss.  It's no worse than a typical high gain amp, but it's still present.  Maybe the new 'silent biasing' in WGTP's updated schematic (and the Bucksears layout) will help this situation.  This was my first 'auto bias' circuit - 5 JFETs and no trimmers... interesting...

Here's a snapshot of my perf circuit on the test bed. 


I'm looking forward to the first build report of WGTP's 'noiseless bias' circuit.  If it tames the background hiss of the original - the Sweet16 could be the perfect metal pedal!

Happy building.
Mike

[WGTP]

Really glad you like it.  I'm always afraid to endorse things too much for fear everyone else will think the suck.  I was pretty confident with this one though.  I built it early on and it still compares well with all the other things that came along latter.  It has unique tone control and serious gain that I didn't want the community to loose sight off.  Might try subing different J201's to see if that helps the noise.

It will be interesting to see how Bucksears "noiseless biasing" lay-out works.   

[Bucksears]

Yeah, I saw the 'Cx' pads on that layout. Changing mine now to add that option.....

- Buck

[WGTP]

I have replaced the document so it now has the original Sweet 16, the revised one with "noiseless biasing" and a 3rd with some suggested mods.   Xcess Sweetness results in Phatness 


http://aronnelson.com/gallery/WGTP/Sweet16?full=1

[MartyMart]

Also dont forget the "Booster 2.5" .... another Jfet classic and a "pre-runner" of the BSIAB !!

MM

[moro]

Sorry for the stupid question, but in the "noiseless biasing" schematic, is the red line supposed to connect above the J201? Or does it go directly from the 1M resistor on the right to the 10K, 1M, 10K, 100uF junction on the left?

[WGTP]

I was trying to clarify that.  It goes from the 1M resistor to the junction.  Sorry.   

[moro]

I was trying to clarify that.  It goes from the 1M resistor to the junction.  Sorry.   

Great, thanks for the clarification!

Sounds like a fun build.