DOD 210 BREADBOARD, JFETS AND ROUND,PIGGY SOUND (?!)

[Renegadrian]

I'd really like to share my today experiment with you...I believe it can be a sequel of that Tillman topic that was turned into a jfet tech topic...

So, I really wanted to see what that circuit was about, the DOD 210 that you can find in the gallery and was drawn by Andy
http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=11215&g2_serialNumber=2
(note that he wrote wrong, actually the DOD 201 is a phaser)

Took my breadboard and made it quickly, even draw a quick layout of it...
http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=36369&g2_serialNumber=1

put in a j201 but the sound wasn't that good...I followed the simple circuit only with a 270k instead of the 220k res.
tried another j201, different batch from the same seller (banzai) bought in different moments.
WOW, didn't think that two of the same kind could be so different!!!

Still the sound wasn't the best I know I could get...So I threw in a 2n5457...So I reached a good level of satisfaction with it...

the first j201 has a "gated, closed" sound, more "fuzzy" than "preampy" - I read on it BG50 and J201
the second j201 cleans a little, while the sound lacks of "level"... - I read on it BG37 and J201
the 2n5457 has a good output and gives a great "round, piggy" sound" - I read on it BH01 and 2N5457
(round piggy sound...It rhymes, gotta write a song out of it!!!) <---sorry, I am an idiot...

As it's so hard to explain my results, here is a quick sound sample - you can see how the first tranny has a "fuzzy" sound on single notes, it gets a lil' better with the second, but just shines with the third...
http://www.aronnelson.com/gallery/main.php/v/Renegadrian/DOD+210.mp3.html

Hope you have had the patience to read all my (useless?!) report...

[John Lyons]

Nice little report there.
I'm sure if you tried a few more FETs you can even find a batter one.

john

[Jered]

  Adriano, here's a little FET test Gus S. taught me.
    Get a new 9V battery and set your DMM to current. Connect the battery negative to the gate and source of the FET.
    Connect battery positive to the red lead of your meter, and connect the black lead to the drain of the FET.
    Your meter will read the IDSS of the FET.
  Now if you find a FET that sounds good all you have to do is match the IDSS and it should also sound very similar. As long as its the same #, J201, 2N5457, etc.
  Jered

[Renegadrian]

thx for the suggestion 

[Ice-9]

The first 2 fets (j201) sound really badly biased where as the 2N is quite close with just a bit gating. its amazing how different jfets that are the same (eg j201's) can be so different. Why is there such a big tolerance difference in these jfets, imagine if a guitar maker built the same model guitar in a production line with such a  huge tolerance level. Maybe this is why mass produced pedals dont use these jfets . Its a shame as the sound when right is so much better than other circuits. (my opinion)

Thans for the test here, its been very useful

Lol, i like the description " Round Piggy Sound" quite a nice deep "grunt"

[Renegadrian]

Yeah Mick, that leads to a huge point...
I could develop a great fet circuit, the best ever done - you couldn't recreate it if you just don't use the same fet...
you might get different results, so my good sound could be your worst...

[Ice-9]

Spot on Adrian,
I've been working with jfets, trying different things with them for about 6 weeks now, (i'm looking for that perfect sound) I have started with BSIAB2 circuit and am trying to develop it to what i want, results were so different at times till i found this forum and the biasing probs with jfets.  I managed to buy 100 j201's and 100 2n5457's to work with.  I have a test rig set up with no bias trims. It's working quite well. The only jfet's that don't sound good are the ones that are way off spec that won't bias correctly.