dbeanerz said:
I am curious of the pros/cons between using an onboard PCI card,
such as the Audiophile 2496 or Delta 44, versus using a USB/Firewire
box such as the Lexicon Omega or the Firepod.
I'm at a bind at where to go next for my setup, to get optimal performance,
and want to get as much information as I can. I currently am using a Lexicon
Omega, but also have a 2496. Since determining I need a pre-amp for my
Shure SM's, I'm curious which to use.
FireWire, if you can.
USB has really bad performance problems for audio above about two tracks.
- It has problems in the way it implements isoch reservation support (don't ask me to try to remember what's wrong with it, though... I don't remember the details), which is one cause of pops & crackles.
- It has poor time stamping, which is a second cause.
- It does not require GUIDs (globally unique IDs) for devices, so multiple devices of the same model may randomly get reversed.
- It uses lots of CPU power when receiving or transmitting a lot of data, a problem that is compounded severely when doing low latency recording.
USB is fine for cheap hard drive cases or thumb drives, but for audio, stay away.
PCI has decent performance, but poor longevity. The parallel PCI standard is basically deprecated for new designs, replaced by PCI Express (PCIe) which is not compatible with PCI cards. The phase-out of legacy parallel PCI has already begun.
Here are the expected phases, along with my best guess about time frame:
- Phase 1: A few motherboards will support PCIe. A handful of motherboards may drop parallel PCI support, offering only PCIe slots. (current phase)
- Phase 2: Most motherboards will provide some PCIe slots. Of these, some will still provide parallel PCI, but a sizable number will only provide PCIe, as it is a much easier bus to support. (within 1 year)
- Phase 3: The cost of bridging PCIe to parallel PCI will drop below the cost of stand-alone PCI cells (CPU bus or HyperTransport bus). At this point, most motherboard vendors will begin using PCIe to PCI bridge chipsets.
Because of high latency, such bridged designs are currently unusable with most audio hardware, and there is no reason to expect that future bridges will behave substantially better. A few pure PCI designs may remain available for a while. (2-3 years from now)
- Phase 4: Most motherboards will drop parallel PCI entirely. Parallel PCI will be largely or entirely bridged, and will be limited to specialized motherboards costing significantly more than general-purpose motherboards. (5-7 years)
- Phase 5: PCI support dropped entirely. (10-12 years)
The PC industry is currently in phase 1. The Mac platform (hardware-wise) has already dropped parallel PCI in new designs. A lot of the motherboard manufacturers will probably follow suit in many of their designs in the near future, as PCIe is significantly easier to use from a board design perspective, which will put us in phase 2. There is already some talk of phase 3 being imminent in hardware circles.
For cheap devices (<$100), PCI is fine. You'll probably outgrow them before you end up with a machine that doesn't support parallel PCI. Even if you don't, you haven't lost
that much more than buying a decent FireWire card to support a FireWire interface.
For more expensive devices, I'd be wary of anything but FireWire. USB just isn't reliable enough, and your computer will probably outgrow a high-end PCI interface before you do.
