my TDA1543 sounds bad

[astouffer]

I just acquired an NEC 602 cdrom drive and decided to wire up a TDA1543 and see how it sounds. First I tried this passive design

http://www.geocities.com/rjm003.geo/...o/diy_dac.html

The 1543 is running at 8v to keep it cooler but the output is too low to be useful. An old Creative 4x drive with analog out is what I am comparing the 602 against. This drives my homebrew 845 SE amp just fine. Next I tried an active design with an opamp for gain

http://www.diyaudio.com/forums/showt...512#post788512

The opamp is configured for low gain so I raised the feedback resistors to 27k and the output went up accordingly. This is listenable but the quality is BAD. No high end at all and everything sounds muffled. The input to the 1543 is taken using three miniature coax wires with all the grounds combined. Before doing any mods I tried the analog out on the 602 and it almost sounded the same way. Any ideas as to whats going on? The 602 and everything else is run from a triple output linear supply.

Any ideas as to what I'm doing wrong?

[EC8010]

Have I got this all wrong? Are you talking about the TDA1543 8-pin multi-bit chip from about 1992 that only has about 12 bits of resolution?

[astouffer]

Well that would conflict with the datasheet's rating of 16 bits. But theres no reason for it to sound that bad...

Other than stacking a dozen or so chips why are there a bunch of projects based off it?

[rfbrw]

Originally posted by EC8010
Have I got this all wrong? Are you talking about the TDA1543 8-pin multi-bit chip from about 1992 that only has about 12 bits of resolution?

Dude, where have you been hiding? The TDA1543 is the greatest thing to hit digital audio in last few years. Well, at least to its followers and they are legion and none too tolerant of unbelievers mocking their idol.

[rfbrw]

Originally posted by astouffer
I just acquired an NEC 602 cdrom drive and decided to wire up a TDA1543 and see how it sounds. First I tried this passive design

http://www.geocities.com/rjm003.geo/...o/diy_dac.html

The 1543 is running at 8v to keep it cooler but the output is too low to be useful. An old Creative 4x drive with analog out is what I am comparing the 602 against. This drives my homebrew 845 SE amp just fine. Next I tried an active design with an opamp for gain

http://www.diyaudio.com/forums/showt...512#post788512

The opamp is configured for low gain so I raised the feedback resistors to 27k and the output went up accordingly. This is listenable but the quality is BAD. No high end at all and everything sounds muffled. The input to the 1543 is taken using three miniature coax wires with all the grounds combined. Before doing any mods I tried the analog out on the 602 and it almost sounded the same way. Any ideas as to whats going on? The 602 and everything else is run from a triple output linear supply.

Any ideas as to what I'm doing wrong?

What chip is it connected to ?

[rfbrw]

Originally posted by astouffer

The opamp is configured for low gain so I raised the feedback resistors to 27k and the output went up accordingly.

Is that 27k or 2k7 ? 27k seems more than a little on the large side.

[astouffer]

The 1543 is connected to the 3 pins of the CXD2510Q. Yes the feedback resistors really are 27k. With the input resistor being 3.3k that should give a gain of about 9, however that much gain shouldn't be needed.

[rfbrw]

Originally posted by astouffer
The 1543 is connected to the 3 pins of the CXD2510Q. Yes the feedback resistors really are 27k. With the input resistor being 3.3k that should give a gain of about 9, however that much gain shouldn't be needed.

The TDA1543 is an I2S formatted device. The CXD2510Q subscribes to the Sony format. For the Sony format you need the TDA1543A.
The 3k3 resistor is not the input resistor. It sets the DC bias point of the op amps. The op amps are configured as I/V converters so the gain is given by I x Rf. The full scale output current of the TDA1543 lies between 1.95mA and 2.65mA typically 2.30mA. The rest I leave to you.

[astouffer]

Ah that makes more sense now. Guess I should have done some more reading up before buying Kind of suprising that it works this well at all. Thanks for the help.