Pearl MC Pre-Preamp

[nate]

You already have my payment, but i'm not in too terrible a hurry.
Sorry to hear about the rain- if its any concelation, I live in Seattle

nate

[Fox]

Promitheus,

Last week, I mailed you regarding the Pearl MC Pre-Pre group buy. Did you recieve my e-mail or not?

If not, I asked whether you have still some Pearl boards and parts left and whether I could join the MC Pre-Pre group buy.

All the best,

Fox

[promitheus]

Yes I did receive your Email and I tried to reply but I cant get a mail through to you.
Do you have another Email address I can try?

[promitheus]

So I am doing some progress.

Just got the MC Pre PCBs.

If you want a high Resolution photo download here.
its big 1,5MB
http://www.audioconnexion.de/mconpearl.jpg

the stand offs must be trimmed but I think it looks good.
The total height is 5cm.

[nate]

any updates?

Nate

[promitheus]

So all the orders are ready.
It took a little longer then I thought.
I sent some ackages on Friday and the rest will be sent on Monday and Tuesday.
A small detail that you have to be carefull of on the board is transistor Q5.
The board was designed using BC550C transistors because at the time I couldn´t find the original 2sc1844.
I left the option open for both.
I did at the end find the low noise 2sc1844 so it has to be solder 1 pin shifted like in the photo I have attached.
The Pins of the bc550 are CBE and the 2sc1844 are ECB.
You can also see Q6. Some people have asked me which side is the round one.

Also be carefull of the resistors which have to be placed verticaly to save space.
For some reason R18 and R19 did not get printed correctly but at least you can see where they are.

The last correct layout is in POST #23

[promitheus]

This is the correct schematic.

[promitheus]

Also there are 2 points on the board called Star1 and Star.
These 2 points need to be connected with a piece of wire.
This connects Audio Star Ground with ground plane.

MC input should be connected to +MC and -MC
MM input should be connected to +MM and -MM

+Out and - Out should be connected to Pearl Input.

[Mad_K]

What is the reason/theory behind a meshed groundplane?

[promitheus]

the meshed ground plane has a few advantages over solid plane.

1. lower stray capacitance
2. pcb remains flat

to power the MCpre board you need to take 29Volts of the Pearl board.
if you look at the picture attached you can see where this is.
on the right side of the board you see an arrow which points to R8 10Ohm, this is the ouput of the regulation circuit which feeds the Pearl.
You can take ground from the resistor R11 10K directly there.
just solder the cable on top.

+29Volts marked red goes to +V on the MCPre PCB
0V marked black goes to GND on MCPre PCB.