New at runoffgroove.com: Professor Tweed

[B Tremblay]

Thanks for the report!  I'm glad that you're enjoying it.

[petemoore]

Most sections of any perf on a schematic, will have something in common with already available perf builds layouts...
  Transistors...I simply follow the schematic's general layout, adding a space here and there for buildability and access.
  Opamps is where I really like to leave some space around the IC socket. These can get tight real quick if spaces around the IC socket are not provided.
  Get the schematic, and the perfboard template printout [at Runoff Groove], that way you can try drafts of your layout on paper.
  I have not too much troubles anymore builing 'freehand' on perf from the schematic, just by following the simple rules laid out above^.
  When I see a really tight spot, or if I need a cramped layout, I use 'upright' resistors [these only take two adjacent holes of perf spacing],  or make above board connections.
  Leaving enough lead above the board for the DMM's probe to touch it, is, IMO, a very good way to make debugging a whole lot easier...
  If youre like me, ..Use alot of sockets for certain voicing and active components. A specific Schematic is easier to refer to...

[Gilles C]

"especially for blues playing."

Hey, how can I resist.

I'm still trying to find some time to build something, that you come up with something else...

Now it's really time for me to remember where I put the few J201s I had left from my other projects... unless I decide to steal them from a few pcbs that never got their place in my collection of effects.  :twisted:

Btw, do any of you know the Crate V15 tube amp?

I could have a good deal on one (for a 2nd amp, when I don't want to use my 40W Hot Rod Deluxe), and a Fender Princeton sim could give him back  some Blues tone.

[Lonestarjohnny]

Rickey, the perf Board is a lot of fun for me, I use a lot of socket's also, makes it easy to get the voicing to sound right for the amp I choose to play it through.
Hey Gilles, that Crate is built better on the inside than most of the new amp's that are mass produced, you can get yourself a nice Vox Chime outa that amp with the right tube selection and some tuning on the circuit.
JD

[Gilles C]

Thanks JD,

You answered 2 of my questions:

1st, >>built better on the inside than most of the new amp's that are mass produced<<<

That's how it look from the outside...

2nd, >>you can get yourself a nice Vox Chime <<<

That's what I thought, because of the design. I am also hopping for some crunchy Marshall vibes...

Now, the only thing left to discover is: is it loud enough to be useable.

Gilles

[Lonestarjohnny]

Yes to both count's, if you like more of a marshall crunch, try a ecc 83 as your first preamp tube, it'll darken and compress more like a marshall.
JD

[Lonestarjohnny]

mr B or Gary,
On your Schem. of the Prof. you show a 1 uf axial cap that is pointed towards the source of Q2, then on the layout you show it pointed towards the 22n cap hooked to the drain of Q3, which way do it go ? I hoping you say it would be pointed at the 22K resistor hooked to Q2's source. I also ended up useing 5K trim pot's, seem's like all my MPF 102's biased at or about 3 K.
Thank's,
JD

[B Tremblay]

The schematic shows the correct orientation.  I'll update the layout shortly.

[Lonestarjohnny]

Mr B. or Gary,
I have finally figured out { NOT to get in a Hurry} Biasing these Jfets until they have had voltage applied for several min's, I like Ed had problem's on biasing the Q2 on the Professor,
After change'in the 100k trim pot's out for 10k's I was starting to get a Lil worried that I had screwed up the Circuit, what's funny I got frustrated and walked away for 10 or so min's and when I came back all three MPF 102's biased out to 4.5 V. with no problem, I had the same thing on the Eighteen, and now I'm perfboarding the Supro, when I finish it I think I have enough insight as to what I'm doing to tackle 1 by myself, I'm gonna try the Magnatone 440 with and somehow, someway I'm gonna add the Maggie vabrato to this, I've seen a pedal thats called a wobulator that get's very close to this so I know it can be done,
Thank's to you guy's and Doug, the rest of the Gang around here for make'in Jfet's so much more interesting,
JD

[jrc4558]

Hi, everybody!
I have just finished the Professor. It is anice sounding cirquit, dynamic and probbly excellent for blues (that is if I only played blues).
However, as with many J-fet builds I did so far, I had to increase the sourse resistors considerably to get ANY output signal at all.
Those that were 1.5K are now 10K and the 470ohm one is 4.7k.
I used MPF102 for all three transistors.
What can be a reason for that?

Thank you runoffgroove for an excellent pedal!

[B Tremblay]

Please post your pin voltages.  It's very odd that you needed to change the source resistors.  How were the drains biased before you change the source resistors?

I've used MPF102, 2N5457, and J201 in the circuit and haven't needed to adjust anything other than the drain trimmers.

[jrc4558]

Ok, I remeasure them this evening.
I still suspect that there's smth wrong with the way those guys label these J-fets at the factory...