is there a chip amp that will give me 50 watts of power

[merickrc]

i am looking to build a chip amp that will power these speakers http://www.zaphaudio.com/BAMTM.html is there a chip amp that will give me 50 watts of power per chan

 

[Nuuk]

What is the impedance of those speakers?

 

[merickrc]

8 ohms

 

[PSz.]

LM3886

 

[Nuuk]

Yes, an LM3886 based chip amp with a power supply or around +/-36 volts should do. You may even get away with an LM3875 too.

 

[merickrc]

thanks for all the help so far will this kit work http://www.chipamp.com/lm3886.shtml

LM3886 Amplifier Kit

 

[mikejennens]

merickrc,
I run a set of JBL L40 speakers, 8 ohm, from an LM3875 (56 wpc, I think). I am extremely pleased with this set-up 😀 . Plus, Peter Daniel (www.audiosector.com) was very helpful, very prompt with replies, while I was building the amp. I'd do another LM3875 without batting an eye 🙂.
Mike

 

[woody]

Merickrc, this speaker uses 2 8ohm woffers in parallel so it is
a 4ohm speaker.

 

[merickrc]

thanks for all the help

 

[star882]

LM3886

That's a pretty inefficient chip. A TDA8920B will easily handle over 50W per channel and is much more efficient. (Aside from lower operating costs, it also means a cheaper power supply and smaller heatsinks.)

 

[pacificblue]

That's a pretty inefficient chip. A TDA8920B will easily handle over 50W per channel and is much more efficient.

Datasheet says: TV sets, multimedia systems, car audio. And a THD of 10% at 45 W into 8 Ohm does not sound too promising.

And with class D you need a much more sophisticated layout to make it even work.

 

[Rainwulf]

I agree with pacific blue.
The lm3886 is a much easier option. Especially for first timers into chip amp stuff.
No inductors to source/wind, much easier pcb layout, much less of a problem with interference and high frequency noise.
And in the end, probably a better sound.

 

[star882]

Don't forget to account for the power usage and heat production (especially bad in a hot climate!).
TI has some digitals that go up to over 300W per channel, but they're SMD and therefore not recommended for a beginner.

Datasheet says: TV sets, multimedia systems, car audio. And a THD of 10% at 45 W into 8 Ohm does not sound too promising.

Run it in BTL mode for 8 ohm. But the speakers mentioned are actually 4 ohms so the amp should be run in SE mode. And although I'm not exactly sure for that chip, in BTL mode, it might be possible to use a different configuration of output filter that only uses two inductors and one capacitor. (A friend of mine did that with the TPA3122D2.)

As for inductors, wind your own air core coils. They cannot saturate and are more ideal than normal inductors. Main disadvantage is the large size. And since it is a hybrid (analog input/digital amplification), the input circuits must be shielded from the magnetic field.

 

[merickrc]

is there a diy kit amp that uses the TDA8920B chip that you are all talking about

 

[star882]

is there a diy kit amp that uses the TDA8920B chip that you are all talking about

The circuit is simple enough to design the amp from scratch.

 

[merickrc]

do you have some ideas on what the amp would consist of becuase i dont know much im new to the hobby of building amps

 

[star882]

do you have some ideas on what the amp would consist of becuase i dont know much im new to the hobby of building amps

Then I'd recommend building something smaller and simpler first. The TPA1517 is pretty much the easiest to start with. Just add 6 capacitors and a power supply and there's your amplifier. (In terms of pure efficiency, the TPA1517 isn't all that good, but it's small so the issues are much smaller. The hybrid digital TPA3122D2 is physically the same size, much more powerful, and much more efficient, but also significantly more complex to implement, especially in BTL mode.)

I would not recommend pure digitals as virtually all of them (or at least the controllers) are SMD and hard to assemble. (Not to mention that they often also need microcontrollers to start them up!) Some of the hybrids, such as the TDA8920B and TPA3122D2, are available in common through hole packages and are just as easy to assemble as any through hole circuit. The circuit needed to make those chips into complete amplifiers is more complex than a traditional analog, but the savings in heatsink, power supply, and the much greater efficiency are well worth it in most applications.

 

[infinia]

I think the OP needs a kit for the first build. Even then there is risk in getting honked with out much handholding.

 

[star882]

http://www.coldamp.com/opencms/open...s/class_d_amplifier_modules/BP4078/index.html
Way more powerful than the requirements, but it will work. Of course, there's much less to learn from building the amplifier.

As for a power supply, use a premade unit. "Wall warts" are good for the smaller ones and are reasonably priced. I would highly recommend a wall wart for beginners as there would be no need to work with high voltage wiring. Of course, the largest common wall warts are 90w (laptop power supplies) and they don't supply very much voltage. PC power supplies are cheap for high power ratings, but getting usable voltages for audio would require modification, which obviously is not recommended for a beginner.

Note that coldamp also sells power supplies, but you have to do a little high voltage wiring. Just have someone more experienced check your work before you actually plug it in.

 

[raypalmer]

For a first timer (like I was until like two months ago) I'd strongly recommend an LM3886 or 3875.

Simply because if it doesn't work the problem can be easily diagnosed from a photograph on a forum. There are only like 8 parts per channel afterall. Just use a big chunk of something for your heatsink.