Class A/B folded cascode amp

[roender]

This is the best sounding amplifier I'v ever constructed!
It don't measure very well but it sound so gooood

 

[Leolabs]

Do the small signal transistors have to be matched???

 

[roender]

Hi Leo,

You must match the following transistors:
J1-J2, BL version, matched at 6mA Ids
Q16-Q14, matched for Vbe
Q19-Q20, it is not really necessary but it's a good thing to do it at the same hfe
Q7-Q6-Q15, matched for hfe

Mihai

 

[Samuel Jayaraj]

Is the voltage for the input stage +-47volts?

 

[roender]

Input stage is boosted with 8V (regulated) over output stage which have 32V unregulated power supply

 

[darkfenriz]

It don't measure very well but it sound so gooood

Don't be so shy.
It probably still measures way better than any gainclone ever built.
Nice one!

 

[lineup]

This is the best sounding amplifier I'v ever constructed!
It don't measure very well but it sound so gooood
.

great amplifier, roender

what i have in 'your folder' is something about SymaSym
so i think you have built one MikeB amp, before

( lineup has got one special folder for each interesting diyAudio member
in his harddrive.
Example this time:
C:/My Documents/diyAudio-persons/roender/070127a_powerstage.jpg
See my attachment below
for this powerstage from 27th of January )

If I have a 'NelsonPass' folder ?
Of course, I have!!!!!
... and you may guess it has got plenty of stuff ... as Nelson IS a very interesting diyAudio profile
C:/My Documents/diyAudio-persons/NelsonPass/



Regards
lineup

... will be back with one more post, lineup comment,
after studying this Folded Cascode amp a bit more

 

[Khron]

Greetings, mr roender

I sent you an email about 2 weeks ago, through diyaudio. Have you received it?

 

[bogdan_borko]

any photos??

 

[roender]

Greetings, mr roender

I sent you an email about 2 weeks ago, through diyaudio. Have you received it?

No, sorry.
If you want, make your whish public ...

Mihai

 

[Khron]

This is a bit off-topic here...

I'm from Romania too, a few hundred km's north of you

I had sent you an email inquiring about the latest version of your evolution of Mr. Bittner's Symasym (schematic, maybe pcb, and in an ideal case, some extra documentation/measurements).

Thanks in advance
Cristi

 

[roender]

This is a bit off-topic here...

I'm from Romania too, a few hundred km's north of you

I had sent you an email inquiring about the latest version of your evolution of Mr. Bittner's Symasym (schematic, maybe pcb, and in an ideal case, some extra documentation/measurements).

Thanks in advance
Cristi

I've send you an e-mail with all the necessary details for implementing "symasym roender style"
Regarding symasym, whatever variant may be, it will measure much better than folded cascoded amp presented here but it will sound a little bit "worse"
Keep in mind, however, that this is a subjective opinion.
I suggest you to test each variants and choose what you like more

 

[atiq19]

class a/b folded cascode amp construction

Roender,

Can I have construction details for your amp?

I'll need pcb layout and building instructions for your amp.

How does it sound if I was to listen vocal based songs?

Many thanks.

Atiq

 

[atiq19]

class a/b folded cascode amp construction

Roender,

I don't know why you can't reply me to:

atiq192003@yahoo.co.uk

Regards

Atiq

 

[roender]

I can't recommend you to build this one because I don't have a finished PCB. Also, there is a small problem with front stages PSU.
I'll update the thread when all this problems are solved.

 

[Symon]

Just for reference MikeB also worked on a folded cascode design.


http://www.diyaudio.com/forums/showthread.php?s=&threadid=52388&highlight=

 

[roender]

Indeed, very similar design, but only as topology

 

[atiq19]

class a/b folded cascode amp update

Roender,

Thanks for your reply. I thought you already tested and finished that amp! What happened to the PSU in front end? I suspect it's minor. How do you compare this version with Mike's Symasym?

Cheers!

Atiq