Portale amp (<5W) for speaker measurement

[percy]

The requirement is to build a simple and portable 5W or less chip amp that I intend to use for speaker measurement duty. Measurements will include distortion measurements. I really dont see using more than 1W but that 1W should be clean and quiet. Lowest possible distortion and noise floor as possible.
Battery powered (9-12V max) would be ideal but not critical.
So what are my options here ?

 

[star882]

TPA1517 if power isn't a big problem, TPA3125D2 if it is.

 

[pacificblue]

I would rather not use the TPA1517 for that purpose. The TDA726x series or the usual suspects from the Overture series are more promising for two reasons. One is that they add less distortion of their own. Two is that they have more thermal headroom, which you may need when you use continuous test signals.

If you want to go the class D route, star882's proposal TPA3125 is appropriate, if you can source it. Class D always has the edge when it comes to portability and heatsinking. For measurements you may however have to shield the output filter to avoid interference. You will probably not need a stereo amp though.

 

[theAnonymous1]

I have a mono TPA3106D1 Class-D board you can have if you want to experiment with it. This was a prototype board I built a couple years ago and it's just been sitting unused since then. It can be powered from a 10-26V supply.

I even have a little extruded aluminum case I could probably put it in for you. It has some scratches and a little dent, but I think you are more interested in function then form anyway.

 

[percy]

Thanks Anonymous, at this moment I am not quite sure about using a Class D amp for measurement duty. I will certainly let you know if that changes. And my first preference is to find something that runs on battery power. If that doesn't work out I will resort to line powered.

here's a few I have narrowed it down to -
LM4952
TDA8944J
TPA6211A1

Thoughts ? Comments ?

 

[theAnonymous1]

How about the MAX9711? It can do 1.2W into an 8-Ohm load @ 0.005% THD and it only needs a 5V supply.

Both the TDA8944J and TPA6211A1 require differential inputs.

How many channels do you need, one or two?

 

[percy]

yes I did look at the MAX9710/1 . I can't remember why I ruled it out but I think a couple of distortion charts threw me off. I will have to look again in detail.
I haven't reasearched any offerings from AD yet.

I need only one channel, but I am not limiting my search by that. Even if there is a stereo or quad amp that meets all other criteria I could still leave the other channels unused.

 

[LAJ]

I liked the LM388

but its been discontinued.

 

[percy]

looks like for under 1W use MAX9710 is the deal, otherwise TDA8944 if additional power headroom is more important.

 

[theAnonymous1]

looks like for under 1W use MAX9710 is the deal.....

I saw what you might have been referring to about the distortion graphs; a sharp rise around 10kHz for low impedance loads.

It looks like for a standard 8-Ohm load, the distortion is less than 0.05% through the full audio band @ 1W.

What will the source voltage be?

 

[percy]

source input voltage would be typical line level output ~2V. wont really need any Av gain.

what threw me off was that with 8ohm loads it has clean power only up to about 1W whereas it can go up to 2W with 4 or even 3ohm loads.