TDA 8920

[palesha]

I am looking for compact class D amplifier. I saw philips datasheet 0f TDA 8920 having 50W each channel. It is bridgable also. More comment on the IC is welcome.
Mahendra Palesha

[Kilowatt]

Check out http://www.tripath.com/audio.htm
They have integrated class T amplifiers - big ones too. Class T is just as efficient as class D and works very much like it, but the switching frequency automatically varies, which dramatically reduces destortion.

[jteef]

How can a varying switching frequency improve distortion? I always thought the higher the frequency the better as long as everything is stable.

For instance, Class D at 200khz vs a tripath that varies from say 50khz - 400khz. Sure, I will agree that the tripath can provide lower distortion. But not lower than a class D at a static 400khz. Am I missing something important?

Do they provide samples for the tripath chips? if they are cheap enough it might be worth experimenting. The eval boards are 250-300 dollars...too much for me. The integrated solutions look really easy to work with though. I might possibly consider their use in the subwoofer section of a cheapish computer speaker setup I am going to build or for my home theater sub.

I would not be willing to use them for quite a while with music though.

The class D IC's i've seen look a lot more complicated to implement for the DIYer.

Another thing I have heard is that the high switching frequencies interfere with your radio reception. So those of you living far away from your favorite radio station might want to try something a bit more traditional. (this came up in a car audio forum where radio is more popular)

jt

[Dave]

I think LC Audio have something avaliable see http://www.lcaudio.com

[Kilowatt]

I don't know exactly what makes Tripath and other class T amps so good, but apparently they're awesome. Variable switching is something that they have though. If I were you I'd listen to one just to make sure they're all they claim to be anyway before buying.

Yes, digital amps interfere with the radio, so the system has to be shielded.

[Jacob]

Originally posted by palesha
I am looking for compact class D amplifier. I saw philips datasheet 0f TDA 8920 having 50W each channel. It is bridgable also. More comment on the IC is welcome.
Mahendra Palesha

Take a look at Zetex (www.zetex.com) class-d solution. They also have extensive datasheets and app. notes.

Jacob

[rljones]

Take a look at this thread on the Tripath. Tripath calls it a class T due to the variable switching nature of their design, varying from 100K to 1.5 MHz. Usual class D designs are fixed at 100 KHz.

Modified TA0104A Tripath Amplifier

The module supplied from Tripath comes on a completely assembled board including a heat sink. You need to supply a power supply, chassis, and a 5 VDC bias voltage. Depending upon which model you choose, power supply voltages can range from +/- 40 to +/- 90 VDC, generating anywhere from 100 W/ch to almost 400 W/ch into 8 ohms.

[subwo1]

The way Tripath does it is good because they only hit the speaker with positeve or negative pulses as needed to reproduce the signal. This way is much more efficient because less filtering is needed. The DSP built in is good too. I would like to try out some chips also.