I've been trying unsuccessfully to build a 2w headphone amp from an NTE990/LM377. It is horrendously noisy, so I'm about ready to throw in the towel on this chip. I've had success with an LM386, but it doesn't put out enough power.

Can anyone suggest a good 1-2 watt per channel audio amplifier with a schematic? The NTE was good because I didn't have to run it hot to get good amplification at the headphones (didn't run at the full 2w).
Space and efficiency are big factors, it will be running from batteries and carried on a person.

Thanks.

 

Have you looked at the LM675 or the ST Micro L165 power op-amp?

Bob

 

LM386 maximum power will generate in its maximum voltage. For the voltage around 4V, 5V its power will be below 1Watt very low.
Did you refer to the datasheet of LM386 it shows how to control the gain by adjusting the Resistor & cap between 1 & 8 pins. Also there are some additional design circuits as well in that.

This will be a problem. Most small 1W, 2W amps need around 6V supply to start works correctly. If you are giving supply from 9V battery then it will be ok.

There are plenty single chip IC’s for your requirements but most are 6V, 8V onwards ones. Ex: KA2206, LA4140, TDA 2002 etc….

Circuits are in the data sheets.

Here is another portable Amp with Discrete components.

http://www.redcircuits.com/Page31.htm

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Any time your running Head Phones from a Power Amplifier, You should put a Resistor in Series with the outputs. Values between 100 to 500 Ohms are suitable.

1) This Will Considerably Reduce that Noise.
2) It will PROTECT THE HEAD PHONES.

** I Have YET to See a 2 Watt pair of Head phones.
Most Head phones are Less than .3 Watts.

And Doing this will probably make that LM377 Amp to be suitable for Listening to.
(Not that I would use that particular IC.)

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I see the reason to include series resistors but what about the damping factor?

With a 470hm: resistor in series you would hear the resonances.

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NOT LIKELY AT ALL, No Matter What Resistance.

But Usually I Use a 150 Ohm, 1/4 or 1/2 watt resistor.

Every commerical amp I have seen, uses a series resistor for the headphones.

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Do you have a fetish about damping factor?

It's pretty well the universal way to feed headphones.

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That explains why headphones often sound ringy.

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I have NEVER had any Good Headphones sound Ringy.

As Far as the Damping Factor goes, It also doesn't change that. As long as the Load has a Much higher Impedance than the Amp, everything is fine. Which is truly the case when using a resistor in series with the headphones.

Besides, Since headphones are Directly against your ears, All frequencys are Much Greater equil to the origional sound quality with No Added Resonances or echo.
That is Assuming the headphones have a Good Response to start with.

Check it Out with a Dual Trace Scope, one side to a headphone and the other side to a Non Inductive Dummy Load.
** This Eliminates all ROOM Acoustics which can REALLY Modify the sound.

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