Official M2 schematic

[hifibluedevil]

PayPal charges 2.99% + $0.30 in fees for sending money when you fund it with a credit card. If the transfer is international there may be also a difference caused by foreign exchange fees.
Most of the payments I have received so far are a little short. I'll communicate with those members about the difference.

Payment sent (total $45) please let me know if this is enough to cover the fees.
best
al

 

[grimberg]

Payment sent (total $45) please let me know if this is enough to cover the fees.
best
al

Yes, that's more than enough.

 

[Ryssen]

M2 frontend is sounding Mega Giga Super nice, as frontend for a headphone amp
I combined it with the upcoming DIY Headphone amp output stage and it's a keeper...
So I made a quick PCB, found some old Teko TK3710 RF-cases for shielding the Edcor's and the M2 Headphone amp is born

Strange....I always hated the combination of transformers and audio...but I was so wrong... CSX1, F6 and now M2 they all sound so nice.

Makes me wonder how the M2 sounds on my big loudspeakers...

You don´t have some gerber files for the pcb´s you wanna share?
How tall are the heatsinks,how much current are you using for the outputs?

 

[ElFishi]

So what is the bias current then? Would anyone care to measure?

Fired up my first channel. Runs at 1.33A.

Unfortunately I have a hard time to control the DC. Even after over an hour of heating it wanders about, sometimes as much as 100mV in half a minute.
Tried to catch it do it on my scope, sorry for the bad iq.

Both channels are are 50mV/Div and 0.5s/div, respectively.
Bottom trace is the ripple as seen on the positive rail. Top trace is output DC. At the left of the screen you see the DC move down and settle on a new level. The kink is where the beam refreshes.

Any idea what I am seeing there?

 

[anilva]

PayPal charges 2.99% + $0.30 in fees for sending money when you fund it with a credit card. If the transfer is international there may be also a difference caused by foreign exchange fees.
Most of the payments I have received so far are a little short. I'll communicate with those members about the difference.

Payment sent for one set of M2 boards including PayPal fee.

Cheers

 

[Zen Mod]

Fired up my first channel. Runs at 1.33A.

Unfortunately I have a hard time to control the DC. Even after over an hour of heating it wanders about, sometimes as much as 100mV in half a minute.
Tried to catch it do it on my scope, sorry for the bad iq.

Both channels are are 50mV/Div and 0.5s/div, respectively.
Bottom trace is the ripple as seen on the positive rail. Top trace is output DC. At the left of the screen you see the DC move down and settle on a new level. The kink is where the beam refreshes.

Any idea what I am seeing there?

pictures , please

which pcb you're using ?

 

[wdecho]

Payment of $42 sent, from my calculations it should cover paypal fees in USA.

 

[ElFishi]

pictures , please

which pcb you're using ?

design found here.

 

[syklab]

Finally after 3 months with the schematic laying on the table, regular looking at it, I understand the finesse of the M2
Thanks!

Would you like to share your PCB pictures on both top and bottom.

Thanks

 

[Zen Mod]

design found here.

when going (over) complicated , it's tough going back , troubleshooting

what can I say - go back and check damn everything

M2 is pretty much automatically set , except output offset ;

steady as a bug

 

[ElFishi]

Any idea where to start hunting? I am puzzled by the chaotic nature of the drift.
Voltage across C3 is steady as is the voltage across R13+R14.
And I can get music through.

 

[pchw]

Sent $42 as well.

Thanks!!,

 

[Zen Mod]

Any idea where to start hunting? I am puzzled by the chaotic nature of the drift.
Voltage across C3 is steady as is the voltage across R13+R14.
And I can get music through.

no clue

I am puzzled by the chaotic nature of entire construction.

 

[generg]

design found here.

I would never trust these clip cables!

 

[gaborbela]

Payment sent!
Thank you

 

[ElFishi]

I would never trust these clip cables!

You mean for power supply? I can upgrade that. Just wanted to fire it up as soon as I had the first pcb completed to see if the design bears out.

 

[JPeitzman]

Payment sent, thanks!

 

[ElFishi]

Generg, you may have a point there: the DC drifts when I touch the supply clips. Will mount proper cables tomorrow.

 

[indra1]

the DC drifts when I touch the supply clips. ...

Also beware of the connector to the transistor, you are passing 1.3A through a tiny contact. It will develop bad contact soon enough taking your speaker while doing so.

 

[ElFishi]

Thanks for the hint. Drains and sources run through 3 pins each, each pin rated at 3A, according to the data sheet.
Will install a speaker protection, too.