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The Unique Geek

The Unique Geek
October 27, 2010

Audio Interfaces 101 (Part II)

Topics we’ll touch on:

  • USB vs. Firewire vs. PCIe
  • Latency
  • Sound Quality

Myths abound in the audio world and it makes perfect sense as to why. If you’ve ever seen a demonstration by a speaker engineer or talked to one it makes your head hurt. You’d think something so common as a speaker is pretty much known inside out by now and there are no more mysteries. But, these engineers, like many engineers, are walking around with math equations bouncing around their heads to help solve simple problems – like, pushing air to sound just like (or better than) what’s coming out of a computer or MP3 player.

What I should say more succinctly is that the components in a recording studio are so complex it’s no wonder there is so much misinformation out there. Let’s start with one of the biggest in terms of an audio interface.

USB vs. Firewire vs. PCIe

USB vs. Firewire

First, I’ll make it easy on you in case you are a skimmer. Firewire doesn’t sound better than USB. PCIe doesn’t sound the best of all. These different computer connections (or means of interfacing) do, however, handle information differently. That’s all.

For the rest of you reading on, I thank you. Besides, the skimmers are dummies anyway. Who needs ‘em?!

USB chipsets are cheaper than Frewire chipsets.  So, if you were in the business of making an audio interface and you have an inexpensive chipset to build something around, chances are this would end up in your more affordable product. If you spent some more for Firewire components – you’d probably go all the way with it and start thinking about a metal chassis and better mic pres for this product line. And that, in a nutshell, is why people assume that Firewire sounds better than USB.

PCI or PCIe is another beast altogether. These are those odd, empty slots in your desktop computer. PCIe slots are right on the logic board (or motherboard for you Freudian minded computer folks) and, thus, spec out best of all in terms of signal to noise [see part 1 of this series for clarification on S/N ratios] . A PCIe interface, then, involves a card that goes in the PCIe slot and a “breakout box” that looks similar to a Firewire or USB interface with all of the usual XLR, ¼” (or what have you) connections.

And what else do these different interface types not have in common? Thanks for asking. They differ in how that information arrives to the CPU. They also differ in bandwidth (how much information they can get to your computer at one time).

USB 1.1 has this much bandwidth:

USB Bandwidth
USB Bandwidth

Firewire 400 has this much bandwidth:

Firewire Bandwith
Firewire Bandwith

PCIe has this much bandwidth:

PCIe Bandwidth
PCIe Bandwidth

Sorry to get so technical on you, but sometimes I think it is crucial to just beat this goobly-gok into the minds of people. How could you ever win an argument at gearslutz.com on whether Firewire sounds better than USB if you can’t show them the bandwidth-finger illustration found here? Alright then.

Hoover
President Hoover

If you are confused about 1394, Firewire 800, PCMCIA cards and so on, you should be. Once you sort it out, you’re okay. Because there is another myth out there that technology changes so fast there is no hope of keeping up. Not so. USB first started development in 1994 and has been going strong since. Its “USB 1.1” specs were published for all of Intel’s nerd friends in 1995. The “USB 2.0” specs came about in 2000. 10 years ago. USB 2.0 handles so much more data than 1.1 that it behaves as fast (if not faster some times) than firewire 400. Firewire goes back to 1996 and PCI slots go back to just after the Hoover administration.

Firewire, the name, is owned by Apple. Thus, outside of Apple World (it’s a magical land with unicorns), you’ll see all of these PCs that have the term“1394.” It’s the same thing. But, if you’re Dell, I’ll bet you’d be damned before you’d ever use the term (or pay to use the term) “Firewire” on anything. Firewire 800 was the next spec to come along in 1394 (just seeing if you’re paying attention) that allowed for even more bandwidth than before. Just like USB 1.1 and USB 2.0. It’s more better.

USB also got a bad wrap several years back when a few failed attempts at big USB 2.0 audio IOs left people with a bad taste in their mouths. They shall remain nameless here. USB 2.0, on paper, is faster than Firewire 400. So, we started to see interfaces that would claim to do 8 in and 8 out simultaneously. As it turns out – they couldn’t actually do 8 x 8 simultaneously.

USB 2.0 delivers information faster than Firewire 400. However, it relies on the host to manage the USB protocol. Firewire delegates the task of its protocol to the actual interface and not the CPU. So, in USB world, there can be gaps in the information stream. That’s a big no-no for audio. We want a continuous stream of data to go to the computer. This was is fine and well for a USB drive holding our blogs (seriously who are these narcissists that write blogs???) and pictures to send info to and fro our computer.

Fear not, though, today’s USB 1.1 & 2.0 interfaces are up to the task. The geniuses writing drivers for interfaces get it now and know how to write a driver correctly and you are able to do 8 x 8 with a USB 2.0 IO now. Soon, USB 3.0 will be here. So, collectively, we’ll all have to get over the notion that USB is somehow inferior to Firewire.

PCIe is ideal if you are sitting behind a desktop and don’t need it to be portable – ever. Thus, PCIe audio interfaces are fewer and further between each year. In our industry (Musical Instruments or “MI’) they are a tiny fraction of annual sales. It couldn’t even be illustrated with a thumb and finger. They are worth mentioning, however, as this is what the coveted Pro Tools HD audio interfaces are and others that are way up there dollar-wise. So, a boy can dream…

Latency

Lennon

Lennon

Have you ever plugged a mic into an interface and heard that John Lennon slap-back effect when you speak or sing? That’s latency. Thanks for reading.

Okay, I should really say more. “Latency is a measure of time delay experienced in a system.” Thank you Wikipedia. It is. It’s simply a the time it takes for audio (or MIDI even) to travel in and out to the listener. In real-time this is annoying if you are strumming a guitar, say, and the strumming you hear is way behind when you actually strum.

The better a driver is written, the lower the latency is. The more money you paid for your IO, the lower the latency (or delay) is that you will hear. The faster your machine is, the lower the latency. There is no one magic bullet to cure these delays you may be experiencing while using a MIDI controller or an audio interface. But, “latency” is a published spec to look for when buying an audio IO.

Mac Pro

Mac Pro

And, there is good news on this front. Increasingly, you’ll find interfaces with a “direct monitor” feature. This allows you to hear just what you are putting into the computer without waiting to hear it come back out – thus, no delay. That and drivers are getting better and the hardware in interfaces are getting better – and you can always just go buy a 12 Core Mac for, I dunno, $22,000?

Sound Quality

Another myth is that recording software doesn’t have a “sound.” This myth continues with an easy, but inaccurate metaphor, “it’s just a word processor for audio.” The same is true for audio interfaces. That inaccurate tall tale goes like this: “heck, they all come from the same Chinese factories and use the same stuff.” Well, most audio IOs are made in A Chinese factory and may have the same Firewire chipsets and DSP chips, for instance. But, believe me, there are a lot more variables that make for radically different sounding interfaces that are in the same price range as one another.

As much as we wish features were all we had to sort when looking into buying an interface; I’m afraid there is more to it. Sadly, every interface sounds different. Some audio IOs sound “brittle” and “bright.” Other interfaces can sound “mushy” and “less defined.” Some of these sound brilliant with a ”sheen” to them – as I’ve heard Apogee’s “sound” described a few different times. Although a computer audio interface seems like a sterile thing – each one has its own personality in terms of sound. I like mine like I like my women – single rack spaced with combo jacks. Wait, that doesn’t even make sense.

TaylorOne thing you should remember is that some of the manufacturers of audio IOs also make preamps. And, guess which preamps they put on their audio interfaces?  You guess it – their preamps. So, if you think of the Presonus or Focusrite “sound” of their mic pres – you’re getting an idea of what their IOs sound like. Because before that mic of yours gets its signal converted to 1s and 0s it goes through their preamp.   The thing to find out is which preamp. Is it the Focusrite Liquid Channel  or some generic, nameless preamp lying around the factory? Anyway, you get the idea.

Ignorance can be bliss in terms of the quality of an IO. I’ve recorded stuff I’m happy with in terms of sound only to try a different IO later and think, “man, my IO stinks compared to this one.” But, you’d be shocked (shocked I tell you!) to learn how different two $500 audio interfaces sound from one another. It’s not a “you need golden ears to hear it” kind of a thing either. Each interface emphasizes different harmonics or overtones even. I heard this once was with 3 different interfaces capturing (it was later released into the wild) the same acoustic guitar at the same time. It was amazing how some overtones simply didn’t exist from one interface to another. You’d hear totally different harmonic content in each one. Really, for the most part, the thing you hear most frequently in cheaper interfaces is a brittle quality – a sound that can be overly bright. When you have a pair of monitors or an audio IO overdoing the brittle-thing you’ll hear it in cymbals and horn sounds (like saxes) the most and it ain’t pretty.

If you are buying online (and really – why would you shop any other way) you have to look around on the web to get the word on the street for which IOs sound the best for your price range. 9 times out of 10 – your IO purchase will be just fine. But, if you’re curious to see the buzz on what you are leaning towards, start hunting around online in user groups, magazine reviews and such to see what “they” are saying. You know… “them.”  They are watching us right now anyway so we might as well give them a shout-out!

Oh and thanks for reading.  Don’t forget to comment or subscribe.  I’ll be back soon with another fun post.

~The Unique Geek

Campbell

Campbell

Side Note: My apologies to the late Joseph Campbell (he’s not late for anything he’s just dead) – the master of comparative/world mythologies. Sir, I understand that myths are “truth embodied in stories.” It’s just so gosh darned easy to use the term “myth” for “what a load of b.s. this misconception is.” Again, my apologies.