Audio Amplification in a Rowing Shell

[Mansoor]

Hi all,

I am working on an audio amplifier for a rowing shell. I will need to power more than three 8 ohm speakers in parallel. The main factors that will determain what chip and design I will use are

1. Battery Life.
2. At least 15 W output
3. Easy interfacing with Microcontrollers
4. passing human voice only as much as possible
5. long part life
6. audio quality

I have researched Class D amps for a couple of days. They offer high efficiency when compared to classical amplifiers. My question is has anyone had experience with a certain chip that fit the criteria above?

I found that ADAU1592 fits most of my criteria, but it says on the manufacturers webpage that it is in production but not recommended for new designs. Does anyone know the reason why the manufacturer is not recommending this design? does it break after a short amount of time? What chips are similar in feature richness do you guys recommend?

Thanks!

[Mansoor]

The ADAU1592 seams powerful enough for my purpose. however that is assuming that i can tie both output channels and attach my three 8 Ohm speakers in parallel to the outputs. I cant figure out that much from the data sheets. it says that the chip can handle a Bridge Tied Load. what do u guys think.

[Pano]

If you are running off a 12V battery, then Ohm's law will quickly get in your way for power.
Figure about 9W RMS for an 8 ohm load running 12 volts. Or ~27W RMS into three 8 ohm speakers in parallel - if the amp will actually drive a 2.6 ohm load.

Using a small input cap can limit the unneeded bass and gain you some power in the vocal midband, where you need it.

[Mansoor]

Thanks Pano

if the amp will actually drive a 2.6 ohm load.

that is the question. The lowest load resistance the datasheet mentions is 4 ohm. but that is per channel. Initially I assumed that I can tie both channels at output to source enough current to drive the speakers. but While reading online about different amps I found some saying that just because an amp can drive stereo 4 ohm per channel does not mean it can be tied to drive 2 ohm mono.

I will be using a 14V - 15 V battery to power the design.