[diredesire]

Hey everyone,
I had a busted laptop and I was scrapping the sound card for the stereo jacks (they're a very small footprint), and i came across this chip

http://pdf.alldatasheet.com/datashee...S/TDA1308.html

TDA 1308
According to the datasheet is a "headphone driver," the package looks like it would be a dual opamp, but I wanted a second opinion on it. Will it do me any good to wire it up and toss it into a CMOY? How do the specs look? I'm always looking to try new chips, but i don't know if it'll be worth my time ;P

If anyone wants to look at this chip, too, i also found it on the sound card
MC34074D
http://pdf.alldatasheet.com/datashee.../MC34074D.html

 

[amb]

The TDA1308 does have a standard dual opamp pinout, but the datasheet infers that it's intended to be a headphone driver instead of a general purpose opamp. Problem is, the maximum supply voltage is only 7V (typical 5V, or +/- 2.5V), which is lower than a single 9V battery. Clearly, this is designed to be used in very low voltage applications and not a good match with most cmoys which have one or two 9V batteries. This chip is also unlikely to be any better sonically than the "usual" OPA2132.

As for the MC34074D, its specs don't look very impressive. It's quite noisy, has high-ish distortion (by modern standards), has low-ish output current capability, and is a bipolar opamp with significant input bias current (which means high output DC offset if used with "standard" cmoy resistor values).

 

[rickcr42]

The OnSemi chip actually specs out pretty good for audio unless you are in the ultra-high speed ultra-high bandwidth camp.

Phase margin and settling time are good,the offset spot on for a single but not dual supply so not for use with a +/- power source.

If there is an area that would give me pause it would be the input ESD protection which is not described in any detail and the output short circuit protection,also not detailed and a thing that can hamper dynamic current delivery in an audible way if overdone.

Power supply current draw is nice but the output current not so very though not a problem if the cans are 300 ohms or better since voltage drive appears good as does the phase margin and "real world speed" under load.

figures 13 and 14 also tell a tale of med-high headphones being better suited though in the end all you can do is plug it in a dgive it a listen.specs can be deceiving and great specs mean no more to good sound than do apparent bad ones and only a loose guide as to end application suitability.a good part used wrong is worse than using a marginal part outside it comfort zone.

Try 'em both and if not to your liking give them away or my favorite-gun them out the window

 

[nikongod]

sorry to bump an old and worthless thread

not really.

this chip looks cooool from the datasheets.

what does the spec "power bandwidth" mean?

 

[amb]

Quote:

Originally Posted by nikongod what does the spec "power bandwidth" mean?

Normal gain-bandwidth numbers are spec'ed at low signal levels. Power bandwidth refers to the high frequency capability of the chip when it's made to output at higher signal amplitudes. For the TDA1308, the power bandwidth is 20KHz at unity gain, which is adequate for portable radios, but isn't "hi-fi".

 

[nikongod]

sweet.

thanks for the reply. now i jsut need to find a faster chip that i can replace this one with. yaay

 

[ericj]

The ad8656 may be the only 'hi-fi' opamp in the same power supply rating.

At least, the specs look really good, and some people say it's the best sounding cmos opamp ever.

 

[nikongod]

ok, so now that i have a suitable amp-chip id'd, where can i get em?

a quick check of newark, digikey, and mouser yeilded nothing.

 

[nikongod]

woot, ad8656 opamp has been obtained in a smt form factor, and installed in one of my pccdp's.

the improvement was nice. seperation and clarity improved. als things sound smoother overall.

a highly reccomended chip.