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-   -   Need an all NPN (Quasi) ops power amp (http://www.diyaudio.com/forums/solid-state/24632-need-all-npn-quasi-ops-power-amp.html)

JojoD818 22nd December 2003 05:43 AM

Need an all NPN (Quasi) ops power amp
 
Hi guys,

Can someone please point me where I can find an all NPN (quasi) output power amp? Power output from 40W up is preferable. An all 2N3055 amp maybe? A full discrete or opamp frontend will also be helpful.

Thanks in advance!

JojoD

AJT 22nd December 2003 06:07 AM

hi jojo,

just about any complimentary output design can be converted to a qauasi-complimentary one to use all npn output trannies...

this is done by changing the pnp output and drivers from a darlington to cfp pair wherein the base of the npn output trannie is driven from the collector of the driver which is a pnp....

early pioneer amps like the sx-770 used this type of outputs...

hope this helps...

JojoD818 22nd December 2003 06:13 AM

Hello!
 
joan2,

Thanks for the very quick response! If it's not too much trouble, would it be possible for you to send me some of your amp schematics? My email, jojod818@yahoo.com

Thanks!
JojoD

AJT 22nd December 2003 06:18 AM

jojo,
i am getting my schematics scanned, will send you once ready...

in the meantime, have a look here:http://www.diyaudio.com/forums/showthread.php?threadid=1750

Alfetta87 22nd December 2003 01:16 PM

Quote:

Originally posted by joan2
jojo,
i am getting my schematics scanned, will send you once ready...

in the meantime, have a look here:http://www.diyaudio.com/forums/showthread.php?threadid=1750


The link is dead...
I'd be interested too in the schematic.

- dan

Alfetta87 22nd December 2003 01:22 PM

Re: Need an all NPN (Quasi) ops power amp
 
Quote:

Originally posted by JojoD818
Hi guys,

Can someone please point me where I can find an all NPN (quasi) output power amp? Power output from 40W up is preferable. An all 2N3055 amp maybe? A full discrete or opamp frontend will also be helpful.

Thanks in advance!

JojoD



I have a PDF file with an all 2N3055 in the outputstage.
Too large to post it, tell me if you're intersted, I'll send it per eMail.
(in german, it is an old Elektor article).

- dan

joensd 22nd December 2003 01:40 PM

Modified Sinclair Z-30
Haven´t built it so no comments.

Cheers
Jens

JojoD818 22nd December 2003 01:44 PM

Alfetta87,

Pls send to ncd@muchomail.com

Mailbox is 6mb. Thanks!

JojoD

JojoD818 23rd December 2003 03:03 AM

Alfetta87,

Got the pdf, thanks! It's sad I can't read German but I think I can follow through. In the schematics, there are parts that are encircled using a pencil, protection circuit maybe, I wonder why?

Have you tried this amp?

Best Regards,
JojoD

planet10 23rd December 2003 08:11 AM

http://www.diyaudio.com/forums/showt...7631#post57631

dave


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