Marsh headphone amp from Linear Audio

[RNMarsh]

Originally Posted by sonidos

Here is what I've concocted. Funny, but after putting the rat's nest together, it all started to take shape just like Mr. Marsh's board.

I did mine all manually. Interesting similar results -- there must be 'rules' the auto feature goes by which are similar to what I learned.

[sonidos]

Originally Posted by RNMarsh

I did mine all manually. Interesting similar results -- there must be 'rules' the auto feature goes by which are similar to what I learned.

It was all done manually. What I did was follow YOUR rules that you posted many pages back. I looked at your board and noticed how you followed the schematic. I then laid out the parts in random fashion and connected all the parts. It was pretty much a rat's nest! So I started moving all the parts around. When I pretty much had it completed, I looked at your board again and it was nearly a dup! It boils down to your explanations making good sense to me.

[RNMarsh]

Thx for the feedback....
BTW - I always do a layout that looks like I am drawing the circuit on pcb. It is also easier to trouble-shoot against the schematic.

[jackinnj]

Originally Posted by sonidos

Here is what I've concocted. Funny, but after putting the rat's nest together, it all started to take shape just like Mr. Marsh's board.

There's a feature in Ultiboard "Auto Parts Placement" -- for audio it's virtually unuseable since, as Richard points out, you have to keep the high current traces away from the small signal traces. You can use some aspects of this feature if you lock the high current and input components into place and it helps "intuit" where parts should go.

[jan.didden]

And of course, netlisting the schematic to the layout gives you automagically a ratsnest that's 100% identical to your schematic - no errors to chase.
Of course, if you make an error in the schematic, that is then faithfully transferred to the PCB as well..

jan

[sonidos]

all good advice...it would save me the QA time to make sure my boards are good and I don't smoke something $$$

[RNMarsh]

Another thing i do during development/prototyping is put the ground plane or the shield plane on the bottom and the signal traces on the top. That, along with a schematic like layout, makes modifications and testing, probing and measuring easier.

These pcb ways make prototyping a new design easier and maybe trouble-shooting during development. Also, later if a part fails.... and for modifying the circuit... easy to cut trace and/or add something without tearing the pcb out and getting to the traces on the bottom.

-RNM

[sonidos]

I am doing my best not to reinvent wheels.

BTW, I bought more 2n5460 jfets. The ones I sourced from HK are mostly junk. I bought a small set from a guy in Florida that actually turned out pretty darn good and they don't tend to drift. The bad news is that he only had a few more left and I bought those up this morning.

I just bought 20 OnSemi 2n5457 that were recovered from some equipment. I'll have news if they are any good once I receive them.

[jackinnj]

You can use the surface mount version of the devices MMBF5457 -- has a different pinout DGS

[sonidos]

yep, but I'm a dumb bunny sometimes. I noticed the power ratings are lower on these devices so i wasn't sure I could just pop these right into place (so to speak).