3886 based power amp kit, how to find the best AND the less expensive PCB board?

[abraxalito]

I have seen products that cost less than the world market price of their raw materials.

Well clearly you can't be talking about chip amps as there's no such thing as the 'world market price' of an LM3886. Its not a commodity like pork bellies or orange juice.

So, how can that be in a rather globalised economy without someone losing money?

Sometimes people choose to lose money in the short term with the hope of gaining over the longer term. Bill Gates' attitude to his OS in China would be an example of that - he's on record as saying he'd prefer it if Chinese copied his system (as opposed to Linux I believe) so that they could get addicted and then he'd be able to make money later on down the road.

 

[pacificblue]

Well clearly you can't be talking about chip amps as there's no such thing as the 'world market price' of an LM3886. Its not a commodity like pork bellies or orange juice.

Of course not. There were completely assembled mechanical, electric and electronic devices that cost less than the raw material of only part of their components. If it had been an LM3886, it would e.g. mean that the complete IC had cost less than the unprocessed silicone inside it which is only one of its components.

 

[ST7677]

In real estate they have a saying that the three most important aspects of a property are 'location, location and location'. For chip amps, these three most important things are 'layout, layout and layout'. Most of the single chip designs copy National's datasheet so the schematics are the same. The expertise of the designer can be seen in how he/she handles grounding, decoupling, placement of critical components and routing of tracks. Secondary is the choice of components - caps and resistors. If those turn out to be the lowest possible quality, its a great tweak to upgrade them. Changing sub-optimal layout though isn't for the faint-hearted.

Very good point abraxalito,
So which ones are the best (sounding) layouts available for LM3886 chip amps?

 

[abraxalito]

I haven't examined many (and listened to none myself - my main speakers are full actives based on 3886 though) but of those I've studied the layout of, Peter Daniels' designs are by far the best.

 

[jemraid]

Hi there,

You might find this interesting: Mick Feuerbacher Audio Projects complete with close up and very detailed photographs.

Jim

 

[AndrewT]

Yes, the PCB came free !

 

[jemraid]

Dear Andrew,

We are in agreement, for once

Jim

 

[pacificblue]

That three-resistor amp is a funny thing. You should not build it before you know what you are doing. But once you know what you are doing, you will not build it anymore.

 

[AndrewT]

That three-resistor amp is a funny thing. You should not build it before you know what you are doing. But once you know what you are doing, you will not build it anymore.

Agreed !!!

But the adoption of a poor topology does not detract from the presentation of P2P techniques.

 

[jemraid]

Hi there,

Here's one I made earlier;

An externally hosted image should be here but it was not working when we last tested it.

LM3876 is the same pin layout as LM3886. The power supply is on some matrix board, again P2P and is to CarlosFM's design. It works very well indeed with a very warm and full bodied sound, in my opinion of course, and in direct comparison to the rather thin and weedy sound from my LM1875 minimalist Thorsten's IGC.

Jim

 

[AndrewT]

The HF decoupling appear to be in the wrong place.
The leads and route length of the film decoupling seem to be longer than the MF decoupling (electros).

Is this a DC coupled non-inverting topology without Zobel, without, RF attenuation, without Thiele Network?
You like living dangerously.

 

[jemraid]

Dear Andrew,

Lol, it's a close up pic, Zobel across the speaker terminal and it is NIGC and I'm still enjoying the music ...... after 7 years of living dangerously.

Jim