LowRider and 2SK30

[RobA]

I've tried to read through the various threads on the LowRider, but I'm still confused. Because I've actually got several 2SK30's and only a couple 2n5457's left that I've got plans for, I want to try the 2SK30's first. I'll socket them to make things easier to deal with, but I'd like to get the insertion right from the start. Anyway, here's the question;

The docs list the 2SK30 as the stock part and show them on the schematic, but when I try to follow the traces on the PCB it appears to me that the PCB is actually setup to take the 2n5457 by default. So, if I do try to use the 2SK30's, I'm going to need to do the leg bendy transistor yoga on them?

Thanks for the help,
Rob

[RobA]

[Deleted since I figured out how to fix my typo in the title...]

[RobA]

First things first, the 2SK30's definitely need some leg bendy yoga to fit the layout.

Well, since I had put sockets in it -- I ended up trying every JFET I've got in it. It did come down to being between the 2SK30's and the 2n5457's, although the MPF102's worked pretty well too. In the end, I went with the 2SK30's. The 2n5457's are more aggressive, but the 2SK30's had a more bass like tone that I think mixes better with the other two voices.

The tracking is perfect up and down the entire neck. It's actually perfect. I was stunned by how good it is.

The upper octave voice is actually quite pronounced on my build. I can only take it up to about half volume with the other voices maxed to get them balanced. I left the caps as specified in the schematic, but I did change to 1n34a's. I also measured the forward voltage drop of the diodes and selected a set with the lowest forward voltage I had (about 270mV).

This pedal is major fun to play.

[Bret608]

Hey, I was just about to post a question on this separately! I'm glad I found your thread.

I'm about to finish up and test a Lowrider board too. At the moment I just have the 2n5457s on hand.

Just to confirm, did you find the board's default layout is for the 2n5457s? In other words, can I just orient them as per the silkscreen on the board, with no leg bending?

Thanks!

Bret

[RobA]

Yes the board is laid out for the 2n5457 GSD pinout. No leg bending is needed for them.

[PimpMyTone]

well I will check tonight but I m pretty sure  (or not)  I did a 180 degree rotation + the leg bending to my 2n5457 .

[RobA]

I'm looking at mine right now and I had to twist the legs of the 2SK30's to make it work.

Looking at the PCB, the left leg of Q3 goes over to R45 and R47 which makes that the gate. So, Q3's got to be a GSD pinout.

[PimpMyTone]

well I tried it like you said and it sounds really bad on my build . Going back to my 180 degree + leg bending .

[RobA]

Curiouser and curiouser.

Can you trace the pinouts of the transistors on your build? I've got mine covered in the back and I can only see that one trace out of the pin on Q3 without undoing everything. From what I can see though, it looks like that leg of Q3 goes to the resistors that hang off the gate of Q3 on the schematic. Have there been revisions of this PCB?

[PimpMyTone]

I see the same trace as you ( wich is why Im so confused ) .

Maybe Brian could help us to put some light on this .

But Im sure of one thing : if I put a 2n5457 without rotating and bending the legs I can barely hear the down octaves .

Now Im wondering if something is wrong with my build .

I will try again again at louder volume tomorrow .

[Bret608]

I think I've heard before that 2n5457s can have different pinouts based on who the manufacturer is. Let me see if I can dig that thread up!

[Bret608]

And here it is!

http://www.madbeanpedals.com/forum/index.php?topic=4768.0

I'll just try it without any leg bending first and see what happens. In the meantime, I've managed to break two ge diodes just trying to get them onto the board!