Official M2 schematic

[ElFishi]

In my data sheet the third pin is also not connected inside the package.

 

[Russellc]

... GB is coming...

After a lot of ordering problems, I´m finally delivered next week (I´ve try about 5 manufacturers: cost gets high then the PCB consists in a lot of vias and price target should be not more then 15€).

Please be patient...

Jean-Paul

How are things proceeding? Take your time, no chassis for me to buy in DIY store, have a few amps waiting for their arrival.

Russellc

 

[DIYspaceW]

From my side I have all the parts waiting for mounting! No news from PCB board! I guess its holiday time and no one wants to play whit their toys...OR?

 

[chatziva]

For all the Greedy Boyz,

😎

Thank you Mr. Pass for your generosity!

Simplicity is the ultimate sophistication...as they say!! Such a simple and clever design!

I've been speculating about the schematic for months now, and I thought it was was going to be something along the lines of the attached.

I did scratch my head too when I first saw the schematic. Initially though that the diodes were biasing zeners and the optocoupler served as some sort of limiter circuit.

 

[Tyimo]

In my data sheet the third pin is also not connected inside the package.

I saw this : http://www.ti.com/lit/ds/symlink/lm185-adj.pdf

 

[ElFishi]

Wrong part.
You need the fixed voltage reference LM385-1.2, see here.

 

[Zen Mod]

yup

 

[Tyimo]

Now I see! Thanks!!!

 

[Tyimo]

Hi!

What about the PSU? Is it a kind of suggested?

Greets:
Tyimo

 

[Zen Mod]

general/common FW jobie - look F4 ,F5 for example

2x18Vac secondaries , two bridges , CRC cap bank

 

[Tyimo]

Thanks! Happy New Year!

 

[hi_aro]

Left me a couple of PCB from GB to this project.
It is a pity to lay the shovel 🙁. If anyone interested send me a PM.

 

[chatziva]

Initially though that the diodes were biasing zeners and the optocoupler served as some sort of limiter circuit...

...not sure what I was thinking... the optocoupler does serve as a current limiter...

 

[Russellc]

jps1964: Are still out there Jean-Paul?

Russellc

 

[chatziva]

I have been staying awake at night thinking about the optocoupler.... now I am not sure what it does.... is it there for setting the bias?

 

[Zen Mod]

just go back some 450 posts

 

[chatziva]

Got it! It's a biaser! That's so neat....!!!

Thanks ZM!!

 

[WalterW]

If I want less gain for my headphone amp, can I connect the output stage to pin 6? And have half of the gain, 9dB ?
Do I have to change more, because of different impedance?
What do I do with the free floating pin 7 ? 🙂

 

[Zen Mod]

no , connect input to pin7

 

[DIYspaceW]

I was just wondering if there is a possibility that diyaudio store would step in
to make the PCB for the M2?????
I think a lot of folks out there have already the parts and want to solder!!! If the guy who wanted to
make a group buy changed his mind he should tell us....!!!