Question about p2p layout for tube pre

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rotation

Well-known member
Joined
Jan 24, 2006
Messages
402
Location
slovenia
Hi!

I'm making new tube preamp, and i'm not sure how to design good p2p layout. Preamp have two tube stages, each tube is decoupled with two caps in paralell.
In general i understand how to make proper grounding, but i'm not sure how to connect each stage to my central star ground.
I thought about wiring all components of the first tube to the bottom of soldering strip (bus grounding), repeat this for the second stage, connect both stages, and run this wire from the end of second stage to my central ground.
To not have B+ wires near input wires, i would have input, cathode, coupling, feedback etc on one strip board, B+ and decoupling on the other. It will look like this:

B+, decoupling
-----------------------strip board

tube tube

input, cathode, coupling, feedback etc
------------s. board ------------s. board

Now, the problem is that my decoupling caps need to be grounded, and i don't know if i should run this wire to the bottom strip board, because than it makes no sense to separate the boards.

So, what do you think about my plan? Should i simply make all connections of each stage on one strip board or not? If i make it this way, it would look like this:
http://www.twin-x.com/groupdiy/displayimage.php?album=87&pos=1
http://www.musiciansgig.com/mila/MILA1-Updated.pdf

I hope you understand what i'm asking, i had problems with the language when writing this..

Miha
 
For audio signal ground, I tend to use the "Ground follow signal" rule, eg connect the ground points following the audio signal input to output.
But look on the NYDave schematic from your link, the ground connections are suggested by NYDave, so just follow the drawing :)
 
> To not have B+ wires near input wires,

Why? The B+ should be "clean". There is no problem having B+ near the plate or the next grid, because simple tube circuits do not reject power supply trash much.

The first grid, and the grid after the gain potentiometer, are the sensitive areas.

The right end of R21 is a trash source. Keep it close to the supply connection.
 
Thanks guys. I already wired preamp this morning, couldn't wait for the replys. I separated B+ and didn't have much trouble doing it. Circuit looks quite nice and i hope it will also work well. But i will follow your instructions next time, that will save me some cm of strip board and make build less complicated.
For the PSU i used G9's circuit (thanks Gyraf), but changed heater regulator to LM317T, because i ordered 317 in TO-92 package by mystake. I hope it will work.

Miha
 

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