What do you think about this LM3886 desigh?

[gabanyayaya]

Hi

A friend of mine just gave this LM3886 schematic to me. Probably not the most simplify gainclone I ever saw... I need some feedback from anyone who thinks there's improvement can be made....and do anybody think this is a good design for the LM3886TF ??? Advice and recommendation is much appreciated...

 

[ratza]

This design is useless. Why don't you use the schematic from the data sheet of LM3886?

 

[jazzy939]

ratza,
Useless in what way?

 

[AndrewT]

I suspect the designer did not know what effect each component had on the performance of this amp.
If the builder does not understand the operation of this specialised schematic then steer clear.
I would not entertain it.

 

[gabanyayaya]

I suspect the designer did not know what effect each component had on the performance of this amp.
If the builder does not understand the operation of this specialised schematic then steer clear.
I would not entertain it.

wow...that much....!!!

you mean a simplified LM3886 circuit is better than this...?

 

[gabanyayaya]

This design is useless. Why don't you use the schematic from the data sheet of LM3886?

ratza how do you tell this is a useless without hearing it???? Does theories good enough to judge the quality of it....I'm very curious... ??? 😕

 

[ratza]

It's easy to explain how it will sound, by just looking on the negative reaction. It will boost the frequencies under 100Hz, it can literally blow your speakers. This might be a poor attempt to create a subwoofer amplifier.

 

[gabanyayaya]

Well... looks like committing a suicide here.

How about this one...he got two circuit and this is suppose to be a simplified version from the first one...any critics.

 

[ratza]

That's exactly what I use (and many others, I think), except that the 470uF capacitors are 330uf paralleled with 100nF ceramic.

 

[mitchelr]

Hi
I have a LM3886 and
I have a 25-0-25 Transformer = approx +/- 35v, could I use the above circuit, or would it need modifying slightly

Thanks for your time
Ron

 

[pacificblue]

Depends on your speakers and your music taste.

With 4 Ohm speakers ±35 V is too much, with 8 Ohm its okay.

The schematics above all show very little smoothing capacity, which makes the amplifiers suitable for high- or mid-range active speakers or for people, who do not ask for too much bass performance.

You should add the Boucherot cell to the output. It costs little, has no influence on the sound, but can prevent the amplifier from oscillating.

The datasheet is recommended reading. All external components are shown and explained, so that you can assess for yourself, which components to use or to leave out and which size they should be.

 

[mitchelr]

I was thinking about using it as a guitar amp, with a 12" 8ohm speaker, I will give it a try

Thanks

 

[gabanyayaya]

That's exactly what I use (and many others, I think), except that the 470uF capacitors are 330uf paralleled with 100nF ceramic.

ratza is the second schematic a yes???? no major flaw?????


how about 1000uF instead of 470uf or 330uf and paralleled with 100nF MKP????

 

[Ted205]

have you checked the datasheet as this is the same layout more or less.

How will you be dealing with any DC on the input ?

 

[ratza]

Without worries, it will run from the very first try. Use a 1...4.7uF film capacitor at input to prevent DC. The capacitors at your choice, I had 330uF at hand when I built the amplifier, so that's what I used 😀
http://sound.westhost.com/project19.htm

 

[wxn]

Depends on your speakers and your music taste.

With 4 Ohm speakers ±35 V is too much, with 8 Ohm its okay.

I guess even 2ohm speakers with +-40V rails could be used if you're careful. Not that it's recommended but probably possible.

 

[pacificblue]

I guess even 2ohm speakers with +-40V rails could be used if you're careful.

No way. You would get a Pd of more than 160 W. The maximum dissipation of the LM3886T is 125 W at 25 °C. Much less for the LM3886TF.