Composite amplifiers - what's the story?

[BamboszeK]

Extremely interested, I like everything about that design... what an ambitious project! Are you using it now? I will have questions after reading the whole thread, but it looks like a thoughtfully constructed amplifier. The headphone amp I did not look yet.

Unfortunately, not. I'm using amplifier build-in my active studio monitors. However, there are pretty high chances that LM3886 is inside them, but definitely not in composite topology 😀
My HPA isn't my daily-driver also. I need to learn mechanical CAD tool first and design some nice enclosure for it.

 

[kaliwraith]

I thought the Mod 86 came with schematics when you actually bought it? The documentation for my Parallel 86 did.

Nope. He stopped providing schematics after a certain version. I personally purchased based on the idea that I would learn something from the schematic so it would be worth the high price tag for the PCBs. I was very disappointed to find out otherwise.


You can make your own schematic with an Ohmmeter and a lot of patience though...

 

[asuslover]

I just found these, I ordered then from national semiconductor back in 2002, with big dreams of building a btl parallel amp per the data sheet. I have the power transformer too, and power supply capacitors and heat sinks, but I never made boards. I ended up using the chassis to build a JLH Class A amp, which sounded good but eventually melted down and I never rebuilt it.

I'm thinking that a pair of composite boards would suit my needs a lot better now than the monster amp I wanted to build originally, and the oversized power transformer couldn't be bad. That article about high levels of negative feedback has got me thinking.

Can you post a picture of the chips?
I have these chips and I would like to compare them with yours,
Thanks

 

[maxhifi]

Here you go. Yours look really similar to mine. I am 100% sure mine are genuine, since I ordered them as engineering samples directly from the old national website, back when National would send out free samples.