Please comment my PCB!

[Mlaen]

The schematic of this preamp is here
I made this PCB but I don't like it Dimensions is 155*45 mm and the pots are not on board so there will be many wires
How could it be better??
The PCB was made in P-CAD 2001 so if someone wants .pcb file let me know (.bmp file is bad because I don't know how to export the image from P-CAD so I just did the screenshot)!
PCB is in attachment in a zip file.

[jaycee]

Expect few comments on a PCB for a Rod Elliot design, the practice is discouraged as Rod makes his living by selling his own PCB's.

[destroyer X]

Can you publish the schematic too.

Very pretty work....very good!

Congratulations

Carlos

[Mlaen]

Thanx destroyer, only problem is that there will be many (MANY) wires on it
It is preamp.
Link: http://sound.westhost.com/project97.htm

[traderbam]

Layout looks pretty good. Nice and symmetrical.
A few comments...

On U1 it is good to keep the track area extending from the inverting input as small as possible. You can make this better by swapping the connections on R104 and R204.

I assume the power and ground connections are just left of U1 on the pcb. I see no decoupling on the pcb nor in the schematic. Op-amps should always have local decoupling.

The gound points for the volume/balance circuit (U3) do not appear to connect to the ground point left of U1. How will you ensure correct ground referencing?

Again, try to reduce the track area off the inverting inputs of U3.

I'd increase the dc bleed resistors R101, R201, R116, R216 to 1Mohm. No point in unecessarily loading circuits.

I pressume C103 and C203 are non-polarized.

Having lots of wires to the pots isn't necessarily a problem. Just keep the wires as short as you can and closely bound to reduce loop areas. Computer ribbon cable is good for this.

Good luck...hope it sounds good.

[Upupa Epops]

Guys, what did you say ? I don't see there any bypass capacitors, so this amp will be potentialy unstabil !

[Mlaen]

Originally posted by traderbam

On U1 it is good to keep the track area extending from the inverting input as small as possible. You can make this better by swapping the connections on R104 and R204.

The gound points for the volume/balance circuit (U3) do not appear to connect to the ground point left of U1. How will you ensure correct ground referencing?

Again, try to reduce the track area off the inverting inputs of U3.

I pressume C103 and C203 are non-polarized.

Good luck...hope it sounds good.

1. Yes, I know what you mean...I'll fix that

2. I was thinking to connect the grounding with another wire or on PCB all free space to use as ground. I'll send it back here when I update the board.

3. Yes, C103 and 03 are non-polarized - would it be better if they are?

Thanx for comments! I hope it will too!

[Mlaen]

Here's the updated board!
(also in attach.)

[boholm]

Upopa's got a very good point. You should definitely put some bypass capacitors on the board too.

And why not try to make a layout, that resembles the one on the picture http://sound.westhost.com/p97.jpg ?

IMHO you should keep the potentiometers on the board as well. Nothing but trouble will come out of it, if you do not.

[Mlaen]

So, where should I put them
I tried to keep the pots on board but then I can't make the PCB