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Old 10th July 2003, 09:11 PM   #1
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Default AC97 codec replacement?

(I don't know if this is the correct forum for this thread so feel free to *bump* if necessary)

I'm using Soundblaster Live's to drive my little home studio here and the noisy AC97 codec is driving me crazy... I'm wondering, because I've read about people here changing codecs for CD players etc., does anyone know of a simple drop-in replacement for the sucky AC97 codec that I could easily add to my soundcard, so my ears can enjoy much-needed silence when nothing is playing?

Thanks!
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Old 10th July 2003, 09:38 PM   #2
fender4 is offline fender4  United States
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Computers are noisy environments, but low-noise, high-end sound cards are out there...check the HTPC forum on www.avsforum.com . There a good bit of info there.

Other than that, I'm not much help. Good luck with it.

-f4
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Old 10th July 2003, 10:34 PM   #3
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Uhm, forgive me if this is too obvious,

But have you played around with the gain structure between your PC and amplifier?

I’ve found that if I try to use a PC's volume setting into a wide-open amplifier that I manage to amplify the crap out of the all the buss noises. On my HP Omnibook you could actually hear the curser moving on the screen.

Running the PC's digital level output wide open with an attenuator between that and the speaker’s works much better.

The noises of course are still there, but for most listening they get stuffed down below the office, and the amplifiers noise floor, while still delivering plenty of dynamic range.

I even got in a little DIY action with an over the counter source selector and home made "passive pre-amp".

-Dave
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Old 11th July 2003, 12:01 AM   #4
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Gain structure? I'll have to look into it more, but AFAICT, everything inside there is operating at either TTL (for the digital stuff) or +4dBu line-level, and there is no attenuation that I have found. Everything's running wide open.

I have experienced what you mention about the mouse cursor, and while it's not that bad right now, it's bus noise, and it does drive me crazy. Thanks for the suggestion though.

I'll be sure and re-read what I've read about gain structure, to maybe make things a bit quieter...
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Old 11th July 2003, 12:32 AM   #5
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If this has any value....I replaced my soundblaster because of hiss and noise to a cheaper 6 channel card (40)CMI 3878-lx.... and now my system is dead silent.....maybe the card was bad but it annoyed me


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Old 11th July 2003, 03:09 AM   #6
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Default a currious little metal box

AFAICT, well my heads sore from where I was scratching it while trying to figure that out. Thank goodness for Google, it helps me be only half the dweeb I used to be (more or less).

+4 dB in a computer? Maybe peak before distortion, but I'd be surprised if, as a SB it was anything but -10 dB reference, like most consumer electronics.

My desktop computer speakers are these little Cambridge Sound Works thingies that were acquired second or third hand. By the time I got them the external volume control was missing. "No problem," I thinks to myself, "I can just use this fancy new laptop and control the volume with the computer.”

Cool Idea, bad implementation. Lots-O-hiss, lots-O-noise, even with the computer volume turned all the way down. Apparently all the way down on the computer wasn’t the cleanest thing in the world.

By controlling the volume with an attenuator in between the PC and the amplifier, I am dropping the output level be a dozen or more dB before it gets to the speakers. All that hiss that was just audible before, gets shoved down into the rest of the inaudible muck. The signal program level of the signal is well above the hash, and comes through loud and clear.

Clear as mud?

With the laptop I could use an external USB or PCI DAC to try and do better, but I just don’t need that for listening to Microsoft Media player conference recordings at the office.

I think Joe D. might be onto something even better. If a generic card has better signal to noise ratio...

The other fun thing about the home made volume control is having computer scientists and engineers try to figure out what the little metal box with the big knob does.
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Old 11th July 2003, 06:10 AM   #7
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a USB DAC! Brill. I'll see if I can get one of those to toy with.

Seriously though. I think I might be wrong someplace about the gain structure. I just changed drivers from the crappy Creative drivers to kX drivers, which allow MUCH more flexibility (you can actually *program* the DSP yourself, how cool is that!) and anyway, I've noticed that levels do seem a bit quieter...

*checks*

Okay, I stand corrected. The output is at -10 dBV. Odd. I know that, using the old drivers, I could get more than that out of it...

*checks volume controls etc*

Yes, everything is set to maximum... I don't know what's different! Somehow the Creative drivers drove the DAC at +4 dBu... I'll have to talk to the driver author (who, fortunately, is VERY responsive on emails and comments) about getting more output.

Of course, it remains to be seen, if that will actually help the problem any--it may be that more amplification just means more noise.

Thanks everyone for all your help.
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