Need an all NPN (Quasi) ops power amp

[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

 

[TonyTecson]

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]

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

 

[TonyTecson]

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]

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]

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]

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

Cheers
Jens

 

[JojoD818]

Alfetta87,

Pls send to ncd@muchomail.com

Mailbox is 6mb. Thanks!

JojoD

 

[JojoD818]

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]

http://www.diyaudio.com/forums/showthread.php?postid=57631#post57631

dave

 

[Alfetta87]

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

JojoD,
If you have questions, ask me. I don't know why some parts are encircled, but to me it looks as if there isn't a protection circuit; but rather the inversion circuit (somebody corrects me if I'm wrong).
I use to build this amplifier (in a very earlier version, more than 25 years ago), with a slightly higher power version - thus not very reliable because of the missing power protection (use a fuse in the output, helps a little). Don't askme the sound, my speakers at that time were equipped with a piezo tweeter, some radio shack midranges and with an a three way universal crossover...

Note that years ago, the NAD 3020 was using the 2N3055, but in push pull (with a MJ2955 as a complementary).

Try it and let us know.

Rgds,
- dan

 

[JojoD818]

Dave,

Thanks so much for the link. 🙂

Alfetta87,

Sound is not much of an issue since it would be used for a school project and most importantly for learning purposes.

I presume that the P3A amp can be outfitted to become a quasi comp ops right?

Regards,
JojoD

 

[Alfetta87]

I presume that the P3A amp can be outfitted to become a quasi comp ops right?

Regards,
JojoD

I didn't get your question???
P3A? comp pos?

Sorry, it's too early for me (oops, 10AM...)

- dan

 

[JojoD818]

Alfetta87,

I know what you mean, I just got up too. 😀

What I mean was the P3A has a CF output topology, can it be modified into a quasi complementary output topology? Since I already have a P3A board to tinker with. 🙂

JojoD

 

[Alfetta87]

I do not know the P3A, but the proposed schematic from Elektor is actually a quasi complementary ouputstage.

Cheers,
- dan

 

[JojoD818]

Alfetta87,

I will study the amp from Elektor first and will try to build it since you have already built it before. This should be a good source of ideas.

Thanks!
JojoD

 

[X.G.]

Hi,jojoD.

I would advice you to try one of the amp series designed by Kaneta which is Japanese DIY expert.Their performances were claimed better than the complimentary amp.

The circuit is 'compeletly complimentary' which named by the designer.I remember that those trans of the simplifier BJT amp are:2 pcs of 2sk30ATM(FET),2sc959/2sa606, 2n3055 and
1 pc of 2N5465(FET).

I had tried the simplifier one,and found that its performance is good even better than the ordinary complimentary amp.The each channel trans of mine are 2sk30(3 pcs),2sd669/2sb649(2 pcs each),2sd600(2 pcs)


regards
X.G.

 

[X.G.]

Sorry for my mistake.Corret it now:

The circuit is 'compeletly symmetrical' which named by the designer (Kaneta).

 

[Easyamp]

You could use national's lm3875 as a possible model to build off of, I never have so Thats about all I can say.

Cheers