The M2 Output Stage in Class A/B, and maybe a Power WHAMMY?

[DIYHarry]

Not cleaned put happy with phoenix connectors

 

[EUVL]

Can you please help me with a direct link to F5Pi ...

https://www.diyaudio.com/community/threads/the-f5pi-f5p-voltage-gain-stage-m2-output-stage-perfectly-integrated.406024/


Patrick

 

[DIYHarry]

Just run out of MELF 470k....2 days delay
Opa 6o4 and Opa 828 are waiting

 

[DIMDAS]

Hi DIYHarry.
I am about to built the same amplifier.
Can you please tell me where you purchased these blue capacitors ?

 

[DIYHarry]

Long time ago
Search for Nichicon ukt

 

[DIYHarry]

Getting finished with my Toshiba project here and nervous 🥹

 

[EUVL]

Getting nervous

Why ? All well proven.
Nothing will happen.




Patrick

 

[DIYHarry]

sry to report- not ok
R13,14 are 0R56--I know too low-high bias

Rail 2x 16,35V
2x 1,56 A
NMOS on Drain source has about 30 V --I shut down after 15 seconds getting too warm -PMOS 0,5V on DS
with trimmer 10k no chance to get dc offset to zero, only between 14,2V and 14,8V dc offset...
opamp pin 4,7 on 9V in relation to GND-OK

3 steps back ---let see tomorrow

 

[DIYHarry]

opamp pin 4,7 on each vdrop 9V in relation to GND-OK

 

[EUVL]

What have you done different to your previous build with Fairchild's ?

Test the M2OPS without the opamp first.
Short opamp pin 6 to Gnd, and try to trim output to 0V DC.

Were you using local feedback or mixed feedback ?


Patrick

 

[DIYHarry]

MFB is the difference and Toshiba -gn8

 

[EUVL]

Read the instructions again in post #74.

Did you include the 2.7V Zener across the 10uF cap, and lower the lower 51k to 39k ?

But test the M2OPS first without those and without the opamp.

Also, if you are using 16V rails, there is no need to use the LM329s, as the opamp can most likely survive 16V.



Patrick

 

[topicreader]

Hello,
Has anyone compared this "M2" amplifier with the original or with the M2x which also contains Edcore?

I have a very well built M2x (Mono blocks, Toshiba 2SK1530/2SJ201, Norwood card) that sounds very nice and is a pleasure to listen to, but the diy bug never sleeps . I'm thinking of ordering an amorphous core transformer from transformer master Bisesik instead of Edcore but unfortunately it's very expensive.

 

[DIYHarry]

Read the instructions again in post #74.

Did you include the 2.7V Zener across the 10uF cap, and lower the lower 51k to 39k ?

But test the M2OPS first without those and without the opamp.

Also, if you are using 16V rails, there is no need to use the LM329s, as the opamp can most likely survive 16V.



Patrick

Ok that's it.
Because I started directly with local feedback and check only BOM local fb and text. At mixed FB it refered to local. Lfb it was written 51 k and so on.
Seems to be misleading for me.
So to be clear, I have to refered also to global feedback too.🤔🙂
Sry stressful weekend.....

 

[DIYHarry]

I limited the rails to 16 V because of overheating and current limit. Target is 23.35V rails each

Btw. Never built a M2 or M2x because I don't like transformers in the signal way😜
I'm the F5 , M2OPS guy

 

[EUVL]

If you use 16V rails + LM329, your opamp will have very limited output voltage, and the DC feedback loop may not work properly.

You should first test the M2OPS without opamp but say 23V rails.
Then add the opamp with local feedback.
Then change to loop feedback, before finally going to MFB.

One step at a time.


Patrick

 

[EUVL]

Someone soldered 2x NMOS on the PCB.
No wonder it doesn't work.




Patrick

 

[DIYHarry]

dont tell all how stupid I´m

I load a lot of work on me these days, BA-recheck and listen session, new VRDN etc...

btw. I fighting at my working local FB Fairchild M2OPs with hearable hum and tried to reduce with cabling, but do not have great success...

 

[EUVL]

Everyone makes mistakes.
I do as well. Just you don't get to know.

Maybe Ground Lifter at the PCA inputs ?
You just need to try and see what works.


Patrick

 

[DIYHarry]

Is it possible that we double the M2OPS to a Turbo, 4x MOSFET per channel?