Distorted audio and unresponsive PC

andy.m · Post by **andy.m** » Mon Jun 02, 2008 1:46 pm

Timur wrote:Usually the ACPI HAL is right. Some older mainboard had problems with it. You can force Windows to discard it though by replacing the ACPI driver with the "Standard PC" driver. This will disable all advanced power-managment features of Windows though, but some systems were reported to give better performance after that. Changing the driver could lead to you not being able to boot into Windows anymore though, so make sure you do a backup and have the Windows CD at hand for a repair installation if you try this.

I agree with ACPI being better than "Standard PC" driver. From what I read I understand that ACPI is more flexible. My motherboard (Epox 4G4A+) seems to have ACPI support. But why, if the motherboard has ACPI support, don't extended interrupts appear in Windows System Information?

I changed the slot to the FireWire controller, choosing a slot that doesn't share an interrupt line with any other device. But it seems that the BIOS makes everything automatically, and it assigned IRQ 7 to that slot even if I forced IRQ 12 for that same slot. IRQ 7 is conflictingThis behaviour is at a BIOS level (I can read IRQs in the POST screen), and happens even before the OS boots.

Timur wrote:I'd try another FW-card first though. It doesn't only depend on the FW-chipset but also on the implementation on the card if it performs good. If your card uses an Agere FW800 chipset then this could be the culprit, because there are known to cause troubles with FW audio-interfaces.

Which card should I try? M-Audio recommends this list:

Manufacturer Product ( Chip manufacturer Chip name ) Power supply
Buslink PCIFW ( Agere FW320-05 ) 4 Pin Power
Pinnacle Link Linx PCI ( Agere FW323-05 ) 4 Pin Power
Syba SD-FW323-3I ( Agere FW323-05 ) 4 Pin Power
Belkin F5U501 ( Lucent FW323-04 ) 4 Pin Power
RATOC PCIFU2 ( TI TSB43AA22 ) 4 Pin Power
Pinnacle 1394 DV ( TI TSB43AA22 ) 4 Pin Power
Digital Research DRFIREWIRE ( TI TSB41LVQ3 ) Bus Power
SIIG NN-400012 ( TI TSB43AB23 ) Bus Power
Adaptec AUA-3121 ( TI TSB41AB3 ) 4 Pin Power
I-Will eLink1394 ( VIA VT6306 ) 4 Pin Power
SIIG NN2633 ( VIA VT6306 ) Bus Power

But my FireWire card is already a Pinnacle DV, that is one recommended by M-Audio.

Timur · Post by **Timur** » Mon Jun 02, 2008 7:11 pm

andy.m wrote:I agree with ACPI being better than "Standard PC" driver. From what I read I understand that ACPI is more flexible. My motherboard (Epox 4G4A+) seems to have ACPI support. But why, if the motherboard has ACPI support, don't extended interrupts appear in Windows System Information?

I cannot tell for sure, but I think ACPI and extended IRQs are independent of each other (IRQs have been introduced after the initial introduction of ACPI I guess).

I changed the slot to the FireWire controller, choosing a slot that doesn't share an interrupt line with any other device. But it seems that the BIOS makes everything automatically, and it assigned IRQ 7 to that slot even if I forced IRQ 12 for that same slot. IRQ 7 is conflictingThis behaviour is at a BIOS level (I can read IRQs in the POST screen), and happens even before the OS boots.

You can try several things here.

1. Set your BIOS to Plug&Play OS = YES. This will tell the BIOS only to assign IRQs to those devices that really need one and leave the others out (like USB interfaces). Windows will assign IRQs for those then.

2. Enable the LPT port and make it use the default IRQ7 so that it hopefully wont be assigned to your FW card anymore.

3. Look for a setup in your BIOS where you can set if certain IRQ numbers are to be "reserved for legacy ISA". This will tell the BIOS not to assign this IRQ to any PCI related interface.

4. Go to Task-Manager and open the settings of several PCI devices. There is an option where you can switch to "manual" resources assignment that may allow you to change IRQs from within Windows (maybe even without a reboot). The LPT interface comes with its own special options for chosing IRQ usage in Windows btw.

Which card should I try? M-Audio recommends this list:

TI based products still seem to be the most reliable and best performing overall, but maybe your card has a bad board layout? We can't tell for sure unless you try another one, sorry. If you've got a friend with a more current PC then I'd try to take both the FW card and M-Audio in another PC to make sure its not just caused by your mainboard's own layout/BIOS.

andy.m · Post by **andy.m** » Tue Jun 03, 2008 5:40 pm

I still haven't mentioned that the FireWire devices (M-Audio FW 410 and mLAN) are connected in cascade (due to constraints in my physical workspace).

PC <----------------(4.5m)----------------> M-Audio FW 410 <----------------(1m)----------------> mLAN

If I disconnect the mLAN, leaving only the M-Audio FW 410 connected, audio quality and computer responsiveness are somewhat better (still worse than using the internal PCI soundcard, yet). If I keep both devices in cascade and disable M-Audio FW 410 from Device Manager audio is bad, as responsiveness is. It seems that cascading of devices negatively affects the overall audio quality and computer responsiveness. But using FireWire for audio is not as good as using a PCI soundcard on my PC.

Is it a good idea to rewire peripherals using two independent cables going from the FireWire controller to the audio devices? Is cascading of FireWire peripherals so bad?

I am going to experiment with the BIOS during the next days, when I have more time.

Timur wrote:4. Go to Task-Manager and open the settings of several PCI devices. There is an option where you can switch to "manual" resources assignment that may allow you to change IRQs from within Windows (maybe even without a reboot). The LPT interface comes with its own special options for chosing IRQ usage in Windows btw.

The option to manually assign resouces for the FireWire controller is grayed out in Device Manager

Timur · Post by **Timur** » Tue Jun 03, 2008 10:12 pm

Sorry, I'm out of ideas here. Best way is to try on a different PC to see how it behaves.

andy.m · Post by **andy.m** » Sat Jun 07, 2008 12:17 pm

To summarize my experience:

PCI audio is better than FireWire audio (on my PC at least).
I had to switch to external audio devices because of a bad "digital hash" noise when connecting both the PCI sound card and the MIDI keyboard audio output to the same analog mixer (a "ground loop" problem). My PC has a noisy ground. I started with a FireWire soundcard. But the MIDI keyboard was connected to the PC's ground via USB, so the "digital hash" noise was still there. So I had to add a mLAN card to the S90 ES. FireWire audio solved the "digital hash" noise issue, but now I am forced to use the PCI card again. When I use the PCI sound card, I have to disconnect all the other devices from the mixer, in order not to hear the "digital hash" noise.

Never connect two FireWire audio devices in cascade (using ASIO drivers).
I am going to connect the PC to the two FireWire soundcards using two different cables.

There is no control over IRQs using modern BIOSes.
No matter how I tweaked the BIOS, I could not assign IRQs at will. Modern BIOSes take control of every aspect of the PC. Gone are the days of ISA PCs with DIP switches, where everything was under control

After all this tweaking, my PC is still performing poorly with Ableton Live. I am going to optimize my system. I will start another thread asking for advice about that.

Timur · Post by **Timur** » Sun Jun 08, 2008 9:40 am

If digital noise is an issue then you could try to use an external box for audio-conversion and stuff and connect that to a PCI card via SPDIF/ADAT/AES EBU (or try an RME Multiface which combines a PCI card with a breakout-box).

andy.m · Post by **andy.m** » Sun Jun 08, 2008 6:08 pm

Well, it costs $850. It's outside my price range. Anything cheaper?