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Which is better for audio recording? FireWire or USB audio interfaces?
I've used USB quite a bit and struggled with a few latency issues (which have since been resolved) but the speeds of FireWire are interesting to me.
I currently run a MacBookPro i5 w/ 8GB of ram.
Firewire became really popular in the mid-90's when Apple dropped traditional SCSI from their boxes and started pushing the Firewire format instead.
Firewire has always been faster and have lower latency than USB, but obviously USB is a far more prevailant interface to be found on virtually every computer made in the last 15 years, but often you have to go hunting for Firewire interfaces.
That said, most of the professional external digital devices run on Firewire - maybe because of the push from Apple in the 90's, but whatever the reason, it certainly seems superior to USB when doing digital production.
Which is better? That depends on a lot of factors.
Bandwidth
Both FireWire (400 & 800) and USB (2.0 and beyond) have plenty of bandwidth available for multi-track audio recording, even at high sample rates and bit depth.
Latency
Latency has much to do with the drivers, the host computer, and the audio interface used.
Now, I've seen someone else talk a bit about throughput jitter. (This has nothing to do with clock jitter on the interface. Don't confuse the two.) Basically, FireWire can operate in a mode where there is a steady stream of data sent from a device to the host computer.
With USB, data can also be sent in a fairly steady stream of data, but if another USB device on the same root hub (external hard drive for example) wants a ton of bandwidth, your audio interface shares what is available. With FireWire, devices also share the available bandwidth when chained together... it is just less common to have more devices.
This is not to say that USB is inferior in this area. Simply plug your audio interface into a root hub by itself, or with low-bandwidth devices like your keyboard/mouse. It's really that simple. Don't have one available? Buy a $10 card and plug it in. Chances are you'd have to do the same for FireWire anyway, but that FireWire card will cost you $80.
Universality (Is that a word?)
How many computers made in the last decade (nearly?) have USB 2.0 interfaces? You would be hard pressed to find one that didn't.
How many with FireWire? Many for sure, and you can always buy a FireWire interface for your computer, Mac or PC, desktop or laptop (assuming available expansion slot). But if you drop your laptop on the way to a gig and need to borrow someone elses', you might not be so lucky to find that FireWire interface. Whether this matters or not is up to you. It may not matter one bit depending on your situation.
Bottom Line
You should choose an audio interface based on whether or not it meets your needs, and not on how it attaches to your computer. While FireWire at a low level has some strengths for dedicated bandwidth, it matters very little (none for many) these days.
You will always find people that say they used to use USB Audio Card X, and upgraded to FireWire Audio Card Y and noticed lower latency. Well of course, they probably bought something a lot newer or better. Either way, they are comparing apples and oranges.
Here's a personal experience for you... on my rig at home, I have a Tascam US-1641 USB audio interface, and my input latency is under 3ms! I haven't even optimized anything. It's even plugged into a chained 7-port hub that is loaded up with a webcam, another audio interface, an external hard drive, and some other crap. It's quite reliable. But again, I'd urge you to look past personal experiences here and there and read through my points above.
Choose an audio interface on its quality and features. If you find something you like that uses FireWire, then go that route. If you find something you like that is USB, go that route. Don't ignore one or the other simply by how it attaches to your PC. The reality is that doesn't matter anymore.
Another thing to consider in the Windows world (and maybe OSX as well, but I'm not familiar enough with that kernel), is latency due to Deferred Procedure Calls (DPCs). This can cause audio drop-outs and latency that is independent of the USB/FW choice. Several tools exist to measure and analyze DPC latency:
I would suggest that having the nicest, most expensive USB or FW interface will still have latency and drop-out issues when connected to a DAW with a bunch of drivers all trying to raise interrupts at a high priority. Choosing between a supercharger and turbocharger to bolt onto a beat-up motor with poor compression and a slipping clutch isn't really a choice at all.
Keep in mind that each processor has it's own DPC queue, so more procs or cores means less of a chance of contention between DPCs. Therefore, I think there are a few choices you should make before you choose between FW and USB:
There are companies making great USB interfaces now (RME). I'm going USB due to the computer upgrade issues - ie apple not putting firewire on certain lower cost computers. Very irritating. I have one of those new pcmcia express cards which has also been removed from all but the 17" Macbook Pro - so choose your connections for the long haul. You'll need a new compute every few years, but can keep an interface for 10+ years.
USB passes each read/write packet through the CPU.
Firewire bypasses each read/write packet, avoiding CPU usage.
This has been the main issue with USB-1.0 and USB-2.0, and I'm unsure about USB-3.0. Intel USB-3.0 requires proprietary Intel drivers, and there are no generic USB-3.0 drivers for Windows platforms, except for Linux.
Many audio related manufacturers seem to be avoiding the PCI/PCI-E bus due to interference. Personally, I prefer PCI/PCI-E as there's better performance overall.
I'm running my Apogee Duet on its own FireWire line. It is flawlessly fast and stable. Can't say I ever experienced this degree of stability and consistency with any USB-based audio gear.
When given the choice, I will always pick FireWire now.
In addition to all of the above answers; firewire also allows simultaneous independent track recording; as does USB 2.0 alesis and other audio hardware producers are now making some good devices for USB 2.0; USB 1.0 is the one you really want to avoid, unless you do not need track splitting and the higher bandwidth
I have been using the PC for recording since 1998. at first we used the regular onboard sound, it was garbage.
I started using PCI sound cards which had pretty much a 0 latency. today a PCIe card would be the best choice.
But if you do not have a PCI/PCIe slot available you are forced to use USB/Firewire
I have used many USB devices and had nothing but problems with cracks. pops, dropouts, time outs, and latency. and I have always used top quality equipment. before someone makes the comment of using crappy computer equipment.
With Firewire I get lower latency, and have not experienced the errors I had previously with USB.
Here's why. USB not only shares bandwidth with other USB devices, it also shares the chipset which controls a lot of other components in the computer.
Firewire has it's own dedicated chip, beware of shotty chip manufacturers. It's a direct BUS, unlike USB (Universal Serial BUS) it's not a bus at all. USB3 will be better, but I haven't seen any USB3 audio devices.
Why do you find USB on most computers, and not Firewire? USB is much cheaper to license and has become the standard, It's not better, just cheaper and broad. you will find that even today professionals use firewire over usb, and most high quality devices that are more expensive are equipped with firewire.
FireWire is often a better option, simple because there are so many other devices that may be connected to USB. By going with FireWire, your audio hardware will often have the entire bus to itself.
Firewire at 400Mbps seems to be nominally lower in speed than USB2.0 at 480Mbps but that's quite misleading since Firewire has bidirectional transfer while USB has unidirectional transfer. As a result, as soon as monitoring comes into play, USB has to share the same wires for payload packets in both directions. So USB is good for a whole lot more jitter and delays since payload packets in one direction hold up all traffic in the other direction.
A number of USB1.1 soundcards offer either bidirectional audio or higher sampling frequency. While the capacity is quite larger for USB2.0, the protocols are more contorted, too, which doesn't help in keeping consistent speed particularly through hubs.
FireWire (IEEE 1394) was designed for isochronous real-time data transfer.
USB data transfer is asynchronous, and is therefore less reliable for time critical data (like sound or video).
