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Discussion Starter · #1 ·
I just noticed (while playing a game with sounds sampled at 8000 Hz and having rate lock disabled) that when I choose any sample rate below 22050 in the Codec Sample Rate section of the Delta mixer, I get a *continuously* noisy output, like a hissing noise. This is not the kind of noise I would expect when using a low sample rate, as it is present even when no sound is being played..


The noise is worse / louder as I choose lower sampling rates. The mixer has no effect on the noise level, even if I mute the output. I am using the Delta mixer as my "pre-amp", the 410 is directly connected to my amplifier, so this noise is quite objectionable in my setup.


I wonder is this "normal" for the 410, is my computer especially noisy, or could my 410 be defective?
 

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Discussion Starter · #2 ·
TTT


Can anyone with a Delta 410 verify for me, when using the analog output, forcing 8000 Hz sampling rate in the mixer, and turning up the volume of whatever amp, pre/pro you have, is it silent or does it hiss?
 

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Quote:
Originally posted by helzerr
TTT


Can anyone with a Delta 410 verify for me, when using the analog output, forcing 8000 Hz sampling rate in the mixer, and turning up the volume of whatever amp, pre/pro you have, is it silent or does it hiss?
8k is silent for me on the 410.
 

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Discussion Starter · #4 ·
Thanks, Cliff... Now that just leaves the question of weather it is my PC or my Delta 410 that's causing the hiss.


Also makes me wonder if it is my PC, can this card sound even better than it already does at 44/48/88.2 if I clean up my PC's noise? I think I'll be off to the electronics store tomorrow for some filter caps, chokes, etc.
 

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Discussion Starter · #6 ·
It's an Intel 440BX for now... Now that I know the 410 should be silent even when a low sample rate is selected, I might take a look at the power supply leads with the 'scope tomorrow, maybe I need a better supply or have some other noisy component in there.
 

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Also have that same problem on VIA KT266A, so I guess that's not a chipset issue...


Other than this, everything's great... except that I still don't have DPL II on the 410 :)
 

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I've been interested for some time in what would constitute a "best in class" component list for an audiophile HTPC -- so I am very interested in the results of your oscilliscope testing. It would be good to know, for example, what components contribute most to noise levels in a PC: does placement of the Delta card next to a video card, HD tuner, or video-input card make a difference? Are some PSs more quiet than others? What motherboards are the best?


Like helzerr, I'm using the Delta 410 direct to my amps.
 

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Yes I have this too, the noise level increases as the sample rate decreases. At 44.1 the hiss is only audible if I stick my ear against the tweeter,around 16K it starts to become audible from normal listening position, as long as the room is quiet. By 8K it is very obvious, even above the TV at normal listening levels.

I can just detect a difference between 24K and 32K, beyond that there is no audible difference (in ear glued to tweeter mode)


It sounds like high pass filtered white noise. I too have 410 conencted straight to power amps, and all channels set h/w out to wave out, although changing the patchbay router has no effect.


The noise comes out of all (6 at least) channels.


The noise seems to be high frequency only, and its pitch / quality does not change as the sample rate is changed - just how loud it is.


A 5K low pass filter affects the level and 'pitch' of the sound, but only reduces the volume slightly, so it sounds like there is plenty of content below 5K, but quite a bit above it as well.


I am doubtfull that this noise is from the PC, otherwise it would be there all the time, and would not change level as the sample rate changes - at least I can't see a simple explanation for why this should be.
 

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Hi Guys,


Just got off the phone with the M Audio test engineer.


The problem you are having is caused by using a 44k buffer for a less than 44k bitstream. There are several things you can do to improve the audio quality from games.


1) Do not enables Rate Locked on the hardware settings tab.

2) Uncheck “Disable Control of the Monitor Mixer and Patchbay/Router by Audio Applicationsâ€

3) And, if possible, set audio sample rate in the game setup to 44k


The above settings will allow Windows Mixer to properly resample the game audio.
 

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Wow, now that's what I call support; nice 1 Cliff.
 
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