Class D Amplifier Challange: Tripath, Yamaha, Texas Instruments

The class D amplifier are now very popular due to it's power efficiency, good sounding, and ultra cheap kit available.

Mostly they are comes in the small modules which most of the user will consider them to use for multimedia or PC sound amplifier. They are built for it, but I will consider to put them on the higher class. They will put on my audio system on my living room with proper listening placement, good audio source. Then I will comparing them one to another.

There is 3 contender in this challenge.

They are all class D amplifier, single rail supply which capable for 12 volt DC, and standard version/non-upgrade components.

All of the modules already has potentiometer for the volume control, 3.5 mm line in jack, and speakers socket terminal. Those are for easy cables swap during testing.

From the beginning, I am very excited to have this audition and whole listening process takes almost a week for me to spot the pros and cons on each amplifier.

On this challenge, I should dig out my very old speakers. It is my first serious built speakers back on 1997. It is 2 way speakers system with 8 inch woofer and 2 inch tweeter. I think it is very suitable for this test.

The sound character of this speaker is quite natural, not so much coloration on the mid range. This 2 way speaker will better in deeper bass, clear highs, good details and larger sound stage.

My speakers cable in this test is Canare 2S7F. They are cheap, high quality built and high durability.

From my previous post here, I always tell about good power supply really effect to the sound quality.

Then I will using high quality SMPS from the old Sharp LCD television. The output is 12 volt 5 ampere.

Ok, now lets find out the result of each amplifier!

Tripath TA2024

Tripath is a Korean company that built this TA2024 IC based amplifier. They also manufacturing others type of IC amplifier and use widely by many company.

Tripath using Class-T technology and basicly is the same just like others class D amplifier using PWM signal.

This TA2024 is quite bulky IC amplifier if compares to others IC amplifier on this challenge. The power efficiency is also the lowest. It is about 88% efficiency. This IC is warm on when operating and no heat-sink is required.

I have several TA2024 amplifier and all of them are suffer from instability DC offset. One channel will having a good DC offset but others is not. I measure the DC offset on this module is about 20 mV on right channel and 290 mV on the left channel. The potentiometer adjustment is an additional circuit which not include in this module. This DC offset adjustment is explain on the Tripath TA2024 datasheet and this can brings down the DC offset to almost zero if it implementing correctly.

For the sound, this TA2024 sound signature is familiar to me. I like the sweet, warm and smooth vocal, but with good frequency response from bass to treble.

The music presentation is strong in the center position. The background noise is really quiet, the sound-stage is good and the music separation is like the instruments are behind the singers.

The music detail is not great. I don't really hear the micro details from the instruments playing. This might because of the vocal dominated that naturally is the strong point from this amplifier..

Texas Instruments TPA3118

This TPA3118 is the biggest power output amplifier compare to others. The output is 20 watt per channel on 12 volt and it could go even higher on 24 volt supply.

The efficiency is also very good, above 92%. The IC surface doesn't feel warm at all when it operate. The DC offset are the best. I measure one channel is 5 mV and the other is less than 20 mV.

This amplifier module is using all SMD components, except for the supply filter capacitors.

Going further to the sound quality, I amazed by the good channel separation. Left and right channel play the role very well, creating the better stereo imaging. This IC have the best detail and large sound stage presentation compare to the all amplifier in this challenge.

The mid range and vocal presentation is thin, not better than the Tripath TA2024. This could be the cause from using SMD capacitor at the input signal in this amplifier module. I also feel the vocal are more forward but it is still enjoyable. The bass and treble are all good in presentation, I have no complaining at all.

All audio frequency are play nicely with this amplifier. It is remind me to the Gainclone LM3875. They are both have very similar sound signature.

Yamaha YDA138-E

It is new for me to see Yamaha return to this semiconductor manufacture. Especially for this class D amplifier, the return of Yamaha in this business is very interesting.

But how this new IC amplifier compete?

I wish I could telling any good about this amplifier. When I compare to the other modules, I couldn't tell any good point about this amplifier.

Sorry Yamaha, you should learn more about what is a good audio presentation for audiophile.

The sound presentation is very narrow, boxes, and no detail. It just like the first class D technology that slow and dull. It seems like I under value this amplifier but the result are night and day since the first time I test this amplifier compares to two amplifier before.

Other than that, the DC offset are worse, just like Tripath TA2024. When I measure, they are around 20 mV on one channel and 250 mV on the others.

Conclusion:
The sound presentation from each amplifier are all different. One similarity from all of them is they are not suffer from pop-up noise, hiss and hum. They like a dead quiet amplifier.

I am now highlight the two amplifier that should be consider to become the good class D amplifier, the Tripath TA2024 for best vocal and dark back-ground noise and the Texas Instruments TPA3118 for dynamic, best stereo separation and details.

End of my words, all of class D amplifier kits on this challenge are all cheap. The price are variate between US$8 to US$15. It is an enjoyable audition I had and several times I should return back between those amplifier to make sure my feeling about the sound signature that I describe above are true and objective.

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