nx-Amplifier: 100 W CFA topology Amp

[Bonsai]

I've just posted up a write up and some pictires on my website (follow the link in my signature below) on my latest amp. This is based somewhat on the sx-Amp, which you may recall I posted up in August last year. However, that was a 15 W per channel class A amp whereas the nx-Amp is class AB 100 W. I am very pleased with the result - really great sound.

 

[Bonsai]

Some pictures

 

[FdW]

The link for the PDF does not work.

 

[Bonsai]

I just checked it on another computer - it works for me. Can you try again?

 

[FdW]

The link still does not work (from the page) strangely enough, if I get the url for the pdf and copy it to the address-bar then it works (windows Vista, MS-explorer 9).

 

[FdW]

Thanks looks like a nice read, I will spend some time with it during the next week.

 

[Bonsai]

Thanks!

 

[naf]

Bonsai, thank you very much.. i found many articles worth to read in your site.
Power Amplifiers articles is what i'm looking for

 

[kasey197]

andrew thank you for these wonderful gifts to the diy community - your articles are of the highest-quality with a truckload of useful background design info ... nicely done ! cheers,

 

[Bonsai]

Thanks Kasey - glad you enjoyed reading them! I'll post up the gerbers and BOM list for the nx and sx Amp in the next few weeks - I am just a bit busy for the next week or so.

 

[Bonsai]

Bonsai, thank you very much.. i found many articles worth to read in your site.
Power Amplifiers articles is what i'm looking for

Thanks naf!

 

[naf]

Hi Bonsai,
i'm start to read article on your site about Ovation 250 but when i've donwload schematic and read the article everything has changed totally different.
Circuit Description doesn't match with the schematic...

"The input is via J1 and into the non-inverting input transistor pair Q4 and Q7 via a 160KHz LPF filter formed by R28 and C10 ...... "

on schematic Q7 and Q4 is output Transistor.... please would you update and include original schematic so i can learn.

regards,
naf

 

[Telstar]

downloaded! i'll read slowly later, but it looks very good

 

[Bonsai]

Hi Bonsai,
i'm start to read article on your site about Ovation 250 but when i've donwload schematic and read the article everything has changed totally different.
Circuit Description doesn't match with the schematic...

"The input is via J1 and into the non-inverting input transistor pair Q4 and Q7 via a 160KHz LPF filter formed by R28 and C10 ...... "

on schematic Q7 and Q4 is output Transistor.... please would you update and include original schematic so i can learn.

regards,
naf

Hello naf

This is a design from 2006. I posted a new circuit diagram about a year ago. I will update text on th site in the next few weeks. Thanks for letting me know.

 

[Bonsai]

downloaded! i'll read slowly later, but it looks very good

Thanks Telstar!

 

[naf]

Hello naf

This is a design from 2006. I posted a new circuit diagram about a year ago. I will update text on th site in the next few weeks. Thanks for letting me know.

Thanks a lot Bonsai,
even it's your design from 2006... this i new from me and worth reading it to gain my knowledge.

 

[Samuel Jayaraj]

Bonsai, is the BC847 (SMD) in thermal contact with one of the Output devices or is it mounted to be in contact with the Heatsink? Due to unavailability of non-inductive power resistors and wanting to couple the nx-amp with a different protection circuit, I would like to make my own PCB (single sided, preferably). Hence, the question about thermal compensation scheme. Thanks.

 

[Bonsai]

Samuel, no it is not in contact with the Heatsinks.

If you wait a few more weeks I will have THP sold screen boards available.

 

[Samuel Jayaraj]

Thanks Bonsai. So how is thermal compensation achieved? Thanks for your generosity with the THP Boards offer. I am a little doubtful about being able to source the NXP parts specified in the Protection Circuitry; hence, mine wanting to design my own boards with another protection scheme. However, I'll look at Element14 and RS for the NXP parts.

Another hint to those having trouble sourcing the specified TO126 transistors - 2SA1538 and 2SC3953 would be great replacements.

 

[Bonsai]

Samuel, almost any 100V TO-220 MOSFET with an rDSON of lower than 10m Ohms will work here. I used the NXP ones ... because I get them free ;-)

But of course, if you want to try a different protection scheme then that's fine.