My "audiophile" LM3886 approach
 

my modest contribution to this forum...;)

Mauro Penasa

It looks good! But I'm not sure about the use of an opamp in front of the LM3886, many people there believe in a "less parts better" approach towards Gainclones. I don't know...

And what's that circuit (the first one on page 2)? Is it a speaker protection or a startup delay?

And where do you get LM3886 in Italy? How much you pay?

Hi maupenas!

Very nice! Thorsten would like it..
But you have overtaken us! It's ages that my friend pushes me to realize this concept! Though he wants it a bit modified, so as to get "constant power" drive, instead of current drive.

For me, the question is: how this all react with Your speaker? [Mine is a two-way bass reflex]
Did you measure the actual Rout? Stability?

Ciao, George

Hello,

I've just glanced at your design, so my question is surely silly. How does your speaker protection cope with negative DC offset?

A very unusual design. The 3886 is just a power booster for the 318. I wonder how it sounds compared to the more traditional approach. Any problems with stability?

No, it's not a power booster..

Doh, I was not looking close enough at the first glance - so I take it back - it IS a kind of a power booster.. though a tricky one. [it's not a unity gain buffer on the output..]

At first I was only looking at the 3886 circuit. My note was referring to that. I still would like to try one day.

Ehm, what would you call it? It's got a unity gain and falls under the 318 feedback loop.

sorry, analog_sa, as you see, in the meantime also I have recognized it

The opamp controls the output current..

So as to be clear: the LM3886 is a voltage controlled bipolar current source in this configuration. It does not have any voltage gain; it has an input voltage/ output current transfer characteristic - which is, in this case, is 100.

And it is stable in this config.

I am sure it is. What about the entire amp? I guess it's fine with the compensation caps.