Hi, my first post...
I have setup a 4 way filter for a multi-driver speaker system with MC DSP Studio using filter parameters extracted from an existing hardware DSP system. The soundcard is an Asus Xonar DSX, 7.1 PCIE (ASIO) mounted in a Windows 7 desktop PC. It's an analog card with 3.5 mm output jacks.
The soundcard is the only add-on card. There are two optical drives and several fans (CPU, PS, case). The PS and CPU fans are the only fans that run continuously.
Now that I have overcome the "learning curve" the filtering is straight forward and elegant. I'm very impressed with MC!
The good: The filtering works as expected.
The bad: I hear much more PC generated noise from the speakers than is audible with my hardware DSP.
The ugly: I was unable to setup a successful filter test with ARTA using analog inputs (motherboard) and outputs (Xonar).
What can be done to reduce the noise? Are there best practices for sample rates, latency, etc.? Ironically the noise level drops by half when I display the DSP Studio Analyzer full screen.
Welcome to the forums! I had a similar problem with two different Asus soundcards (specifically the DX and Essence ST) at one point; persistent noise that changes volume/tonality based on PC activity is probably a hardware problem, not a software problem, but I have some suggestions related to both hardware and software:
Hardware Tweaks:
1) Many of the Asus sound cards cards draw power from a molex connector instead of through the PCI-e slot to isolate the card from MoBo noise. If the DSX has such a connector, try using a different molex bundle out from the computer's PSU, preferably a bundle with no other peripherals on it. I heard a dramatic difference in the noise floor based on which molex was connected to the sound card. If your DSX draws power through the PCI-E slot, try a different PCI-E slot as some are noisier than others.
2) If you have a different PSU around the house, try swapping it into your system. Some PSUs just give off a lot of electrical noise, and it's hard to know if yours is a "noisy" one or if you have a different issue. I had one PSU that was significantly noisier than another.
3) Try to minimize the length of cable runs and make sure your audio cables have adequate insulation (or are kept away from other cables), especially on unbalanced cable runs like the ones coming out of the DSX. Long cables can act as antennae, and if you really are hearing changes in line noise linked to changes in monitor states (as opposed to changes in CPU states), it's possibly because your cables are picking up interference from your monitor, either through close contact with a poorly insulated monitor cable, or through EMI from the monitor itself (especially if it's an older CRT-type monitor).
4) At the end of the day, you may just have an electrically noisy MoBo or PSU, in which case you either need to find a quieter MoBo or PSU, a better insulated soundcard (possibly external), or a way to attenuate the noise. The higher end Asus soundcards are somewhat better insulated, but are still potentially susceptible to noisy PSUs or MoBos (ask me how I know). You may want to look into some inline line-level input attenuators to place between your DSX and your amplifiers, like these:
http://www.amazon.com/Harrison-Labs-Line-Level-Attenuator/dp/B0006N41B0. Depending on how loud the line noise is, you may need more or less attenuation than that, but that sort of thing will effectively reduce the volume of the noise without compromising sound quality (although it will likely reduce the maximum playback volume of your system, depending on your amps' input sensitivity).
Software Tweaks:
1) The Default Asus drivers did not work well for me in terms of latency, drop outs, etc. I recommend trying out the third party Unified Asus drivers available for free here:
http://maxedtech.com/asus-xonar-unified-drivers/. This probably won't fix your hardware noise problem, but it may help. It will also potentially be helpful down the line as the stock drivers have high latency and are flaky.
2) You may also want to try disabling/uninstalling the driver for your default soundcard for troubleshooting purposes. Sometimes driver conflicts can cause noise (but usually not persistent noise like you're describing).
As for the ARTA measurement setup, I haven't used ARTA specifically, but is there any reason you don't want to use the input on the DSX (instead of the MoBo input)? With most of the measurement software I've used, it's easier to setup with inputs and outputs coming from the same device.
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Topic: Noise From System With DSP Filters and Analog Sound Card [Solved] (Read 7390 times)