SHO + Tillman Build Success

[jafo]

Hello, all. Time for my first post (I've been lurking for a while). Using Radio Shaft parts, I managed to insert a Super Hard On into Tillman's preamp. The result isn't as dirty as that sounds, but is very satisfying nonetheless. Pics and clips to come later.

Stage 1, the SHO, more or less following a MacGuyverized schematic. I used an IRF510, 22k drain, 50k bias pot, and a 12V zener between Source and Gate. Gotta use what's available, no? This gave me a sparkling clean boost, and finally let me hear my guitar. Sooo much better than going through a GuitarPort. Clarity, yadda yadda -- you all know the deal. Still, it was too clean and neutral to go straight into the sound card on its own, so I decided to add a jfet stage after it.

Stage 2 was originally the Orman jfet output stage with the LED as a bias resistor. Couldn't get it to bias correctly, so although it could scream and sing, it crapped out constantly. Maybe if I'd used a trim pot for the Drain... but I didn't want to run out to the Shack again. Scrapped until I figure out what I'm doing. (Still, I really like the idea of a biasing diode -- it amplifies the positive cycle more than the negative, creating asymmetric distortion in much the same manner as a tube is supposed to. Way cool.)

Stage 2, Mark 2, is the MPF-102 variant on the Tillman preamp that you can find on the Hawes TV site. I omitted the Zeners, 'cause a) they aren't necessary, and b) I'm lazy. Sounded great! A little too much gain, and too dark, perhaps, but it was very responsive, smooth, warm, and sweet. A winner! Still, it clipped the jfet too much, as a trip to a wave editor proved. So:

Stage 2, Mark 3. I replaced the 560 ohm source resistor with a 1k. Less gain, but much more headroom. Sweet and warm, and lets me get some grit just by digging in a bit -- perfect for a Stones fan like me! I've toyed with op amp circuits and could never get this kind of feel from any of them (although the MXR Distortion+, a badass mean mofo, is a fave).

I'll prolly tackle a TSF next, maybe with a jfet or mosfet first stage for some asymmetrical goodness. (And/or run it on 5V.)

A couple of things come to mind. First, the feeling of sheer omnipotence that comes from a successful build, especially when you mod it (even as little as I did the Tillman stage). That's a pretty good feeling! Second, I should've done this years ago. It's so much easier and cheaper than I expected. And third, is there ever a stage at which playing with your new toy is more fun than planning the next one? 

Anyway, pics and clips to come soonish.

[amptramp]

Welcome to the board!  It's always good to hear from someone who has built a pedal then tweaked it to get the sound exactly the way he wants it.

Looking forward to the pics.

[stringsthings]

welcome to the definitive board of DIY !

A couple of things come to mind. First, the feeling of sheer omnipotence that comes from a successful build, especially when you mod it (even as little as I did the Tillman stage). That's a pretty good feeling!

isn't that a most excellent feeling?  

... is there ever a stage at which playing with your new toy is more fun than planning the next one?  

good question ... it can be tempting to adopt the "more is better" philosophy in terms of planning/building/testing/designing ... but it probably comes down to the individual ... i go thru phases ( no pun intended ) ... making a circuit .... tweaking circuits .... studying about circuits .... using the circuit ... staring at blank pieces of paper   with the word "new design" at the top ...

as long as you're enjoying what you're doing, it can be a very nice way to spend time

[jafo]

Wow, RL really takes up a lot of your time. So does having your kid inadvertently infect your system. Anyway, here are some pics of the build, warts and all. I haven't found an enclosure that I like, and still need to trim leads (I wanted to give myself a few days to be sure I was happy). If you look carefully, you can see that I have both the 560 and 1k drain resistors from the jfet -- oops.






And some audio clips recorded directly to sound card, no effects processing. (Please excluse the sloppy playing.)

hummer
singlecoil

[jafo]

as long as you're enjoying what you're doing, it can be a very nice way to spend time

And how!

[DavenPaget]

Wow, RL really takes up a lot of your time. So does having your kid inadvertently infect your system. Anyway, here are some pics of the build, warts and all. I haven't found an enclosure that I like, and still need to trim leads (I wanted to give myself a few days to be sure I was happy). If you look carefully, you can see that I have both the 560 and 1k drain resistors from the jfet -- oops.






And some audio clips recorded directly to sound card, no effects processing. (Please excluse the sloppy playing.)

hummer
singlecoil

I just need to mix both circuits without removing any resistors right ?

[jafo]

I just need to mix both circuits without removing any resistors right ?

ISTR that I just did a low-pass filter between stages (the cap followed by a grounded resistor), but just try it with and without, and you'll get what works for you. You'll end up tweaking anyway. (For example, after a while I realized that the last two caps are too big, which gives me too much bass -- the cutoff frequency is lower than I want.) Luck!