[yejun]

http://focus.ti.com/lit/ds/symlink/tpa6112a2.pdf

Differential input, 150mW output, very low THD.
I guess it will sound better than CMOY.

 

[jasonhanjk]

This is a surface mount chip, do you have the ability to solder it?

Anyway, I have not use it but it is most likely to be used at speaker rather than headphone. I may be wrong but it is not worth the risk.

If you see the spec figure 34, the max loading is 64 ohm. How do you expect to load a 300 ohm Sennheiser HD600???

 

[daniel422]

Hmm. Max loading isn't 64 ohms, it's just the number they spec it up to. Most chip manufacturers (and consumer electronics manufacturers) don't spec things for the HD600s (as wonderful as they are). 16 and 32 ohms are the most common headphone impedances, so that's what they will show. I suspect it will have no problem driving a higher impedance load -- in fact THD will probably be a LOT less.
That being said, this chip doens't appear any different that 50-60 other audio amps being offered by TI, National, or anybody else. THD is OK, power is OK, PSRR sucks (check the misleading spec in the electrical characteristics table vs. the curve in back) at lower f (like 60Hz power lines).
This chip is over 3 years old. This is almost ancient for these things. Some of TI's newer parts are much better (and National's).
As for being surface-mount -- it's a 10-pin MSOP. Certainly pretty small, but doable with a magnifying glass (or none if you're good at these things). The key is having a board layout to mount it on (although I've made spider legs on MSOPs to DIP before -- it's just not a very reliable connection).

 

[Tomo]

Hey,

I would avoid anything with "audio" written all over it. They are most commonly poor in quality.

Look at THD, for example, 0.4%. OPA134 gives like 0.001%.

You do the math.

Tomo

 

[yejun]

Quote:

Originally posted by Tomo Hey, I would avoid anything with "audio" written all over it. They are most commonly poor in quality. Look at THD, for example, 0.4%. OPA134 gives like 0.001%. You do the math. Tomo

The load is different.

 

[Tomo]

Hi,

That is correct. I picked one for 600 ohms.

I still don't like it. It doesn't take enough voltage. It can't have much gain without increasing THD. Speaking of which, it probably has pretty low slewrate. Good gain for that chip is probably G=1 or -1 which defeats purpose.

I would probably want cable driver designed to drive 50 ohm cables. I mean, if you want to drive low impedance headphones and G=1, then go right ahead and use closed loop buffers.

T