best car sub amp chip

[soundNERD]

I'm starting to collect the stuff for my car in a couple years, and want to know what the best 12V single supply chip is. I want about 500W (so I can bridge them if needed) to power an 8 inch sub from my old logitech z680s. Class D would be nice to not need a ton of batteries or create a heater in the trunk.

Are there any chips designed for car use? The spaker is 8ohm so bridging would work perfect.

thx,
mike

[SkinnyBoy]

I'm a little confused... or maybe you're the confused one....

13.8volt rail to am amp provides about 25watts output at 10% thd max (with bridging).... do you intent in steping the voltage up, or using more that one battery?

[macboy]

13.8volt rail to am amp provides about 25watts output

Not with soundNerd's 8 ohm load it won't.
Let's go through calculations:
assuming the amp can provide rail to rail output (which it can't), you will have a peak voltage across the speaker terminals of 13.8 V. That corresponds to an RMS voltage of 13.8/sqrt(2) = 9.76 V. The RMS power is then 9.76^2 / 8 = 11.9 W. More realistically, the clipping voltage of the opamps will be around 2 to 3 volts (each), giving you a maximum peak voltage across the speaker of about 9 V. Do the calculations again and you will get about 5 W of power.

soundNerd, your goal is a pipe dream. To provide 500 W RMS into 8 ohms, you will have to provide an RMS voltage of over 63 V across it. That corresponds to 90 V peak. So you'd need a single-ended amp powered from about +/- 95 V rails, or a bridged amp powered from about +/- 50 V rails. Even if you could build the SMPS necessary to get the power rails (don't even try it), you certainly couldn't use chipamps to deliver it the power to the speaker.

Overall, this is pretty close to the silliest question you've asked here in a while. Really. People here including myself are happy to try to be helpful and answer real questions, but this is over the top. Do some research on your own beforehand.

[macboy]

soundNERD,
the best you can do without building a very complex power supply, is to try using an amp which has some built-in method of boosting the power supply voltage.

Try Philips TDA1562 which can deliver up to 70 W into 4 ohms, bridged. Also try looking at their Car audio catalog which lists all of their amp chips designed for car audio use. You will not find anything even close to 500 W, but you will find something. Also note that you will definitely want to try to use a 4 ohm speaker. These are the norm for car audio, and for a very good reason. An amp needs less voltage to deliver the same power into 4 ohms than 8.

Your next major challenge is finding a place to buy these things. Philips semiconductors are not as readily available as National or TI.

[soundNERD]

aren't there chips designed for 12V operation?

[rayban68]

I believe that TDA1562 runs straight off the battery, anywhere from 9 to 18 volts. Looks like a pretty cool solution, I wonder how difficult it would be to do up a pcb for it?

If I recall, it put about 22W into 4ohm before it has to use the voltage boost from the caps.

Back in my high school days I had two 12" subs bridged off 2 channels of a 40x4 amp, so i was putting at most 40watts into each sub, it ripped holes in my trunk seals in the first day, and let me tell ya, that stereo pounded pretty loud. 22watts isn't too far away fom 40 watts in the audio world, so don't focus too much on the 500watt number, as that is pretty much overkill anyways.

[soundNERD]

that looks like a good idea. how about that tda2050 chip that another memeber is using in a comp speaker amp and getting a hum noise. somebody there said that is a car chip, but i can't find any info about the power handling of it.

i guess 500W is overkill, but i want at least 100 or so, even though this speaker is pretty efficient.

thx,
Mike

[SkinnyBoy]

Originally posted by soundNERD
that looks like a good idea. how about that tda2050 chip that another memeber is using in a comp speaker amp and getting a hum noise. somebody there said that is a car chip, but i can't find any info about the power handling of it.

i guess 500W is overkill, but i want at least 100 or so, even though this speaker is pretty efficient.

thx,
Mike

look.. the most power you can get into an 8ohm speaker withoug steping the voltage rails up is like 5 watts rms... feel free to aim for 100, but it won't be 100watt rms....

[soundNERD]

well, then how does that 2000W alpine sub amp at tweeter work?

[net-david]

Originally posted by soundNERD
well, then how does that 2000W alpine sub amp at tweeter work?

By using a power supply to increase the voltage from a single +12v to something like + and - 50v or more. Have a look at ESP Project 89


David