The minimum requirements...
...for a computer based hard drive recording system are a computer that is fast enough for what you want to do, a hard drive that is fast enough to keep up and has enough storage capacity, recording software and an interface that does Analog to Digital and Digital to Analog conversion (ADA). For this article, we are focusing primarily on interfaces that have at least four analog inputs and outputs that can be connected to an analog mixing console if desired. While you might get by with older, slower computers for stereo audio, for multi-channel use you need something a bit faster and newer. Luckily, computers are pretty cheap now. The first thing you'll need to decide is which platform to use, PC or Macintosh. If you already have a computer, this may be a moot point. Both have advantages. The PC is good because it's fast and cheap and there's a lot of good software and hardware available for PCs. The downside is that they're much more difficult to configure. Macs on the other hand are pricier and have less support and a smaller installed user base. At the top of the line, Macs are very fast and are easier to set up and use. Of the half a dozen people I spoke too while researching this article, the Mac vs. PC camp was split almost down the middle although there was a bias towards the Mac on the high end. Minimum suggested Mac Requirements are usually a G3 or better with 96- 128 MB of RAM, while on the PC side, you'll want a 250-300 mHz Pentium with 128 megs of RAM. The hard drive you record onto is especially crucial. I spoke with Bob Cacciatore at Xistor, a company that specializes in digital audio storage mediums, and he strongly recommends using a SCSI drive, because they're 'smarter' due to RAM caching. Ultra-wide is the best, if you can afford it and you'll want at least a 10 gig drive, preferably an external drive, with all of your applications and system on the internal drive. Crucial factors to address when buying a drive are seek times, density, rotational speed and data throughput.
Should you buy a Pro Tools system?
Pro Tools is the de facto standard for hard drive recording in most professional studios, much like two inch tape is for analog studios. Unlike most of the newer systems that use a PC for much of the processing and DSP, Pro Tools is an integrated and proprietary hardware and software system. With very few exceptions (See the MOTU section), you'll need Digidesign software and hardware to run Pro Tools. As this is a product with years of research and user feedback behind it, it works very well and has lots of support from third party manufacturers. So, if you want to be able to transport your tracks to other studios to work on them, for overdubs or mixing for example, Pro Tools compatibility is essential. On the other hand if you plan to be working primarily in your own studio and starting and finishing all your projects there, then Pro Tools is not essential. In fact, there are quite a few systems available for much less money and with even better specs that might work just as well or even better for you.
Do you need an expandable system?
Most, but not all, of the audio cards today are expandable. But, most of them will also require additional PCI slots, which can be a problem. (The work around is to get a PCI expansion board) Some systems like the MOTU will support up to three interfaces from one PCI Card. In many cases, it's a software issue. The Gadget Labs boards, for instance, support multiple units on PCs, but not Macs. This may change in the future and is mainly just an issue of driver development. This may also be the case with other units. This is something to look at on a case by case instance, as it's constantly evolving.
Will you need to sync to tape?
This is beyond the scope of this article, but be aware that if this is something you want to do then you need to make sure the system you assemble can reliably pull this off. Some of the options for sync are MIDI Time Code (MTC), SMPTE Time Code and word clock. Very few interfaces will read SMPTE directly which is how most analog recorders will need to sync up, so you'll need some kind of SMPTE reader/generator/sync box. According to several people I talked to, MTC isn't really reliable for digital audio; you should use word clock instead. If you're using MDMs like ADATs or DA88s, this is less of an issue since the ADAT BRC for example generates several types of sync tracks. Check the MOTU section below for more on this subject.
What Software And Computer Will You Be Using?
This will affect the audio card you'll need. Not all boards support all of the available recording software packages. Both PCs and Macs use the PCI slot, so in theory all boards should work on both platforms. But, you need driver software for your computer and your software. As new software is written and updated, this will constantly change. Make sure that the hardware and software in the system you assemble works well together.
Many of the newer interfaces are 24-bit and record at a 96k sampling rate. Without getting into digital recording theory, suffice it to say that, in theory, the more bits and the higher the sampling rate, the better a digital recording system will sound. In comparison, CDs and DATs are 16 bit 44.1k, while early ADATs were 16 bit 48k. But, when I asked people in the industry what they thought about 48k vs 96k, I got two different answers. "96k is all marketing hype," was the answer I got from several different manufacturers. Ryan Kallas of Sea Sound says that the A to D chips, which are pretty much the same in all of the units at this point in time, actually spec out better at 48k.
Several other people I talked with said that 96k just uses too much hard drive space and that it demands more of the host computer's resources. But, when pressed most of them agreed that yes, 96k does sound better if you've got the hard drive space and a fast enough CPU, not to mention a high quality signal path (mics, pres, etc.) into the computer. David Blackmer, who is the brains behind Earthworks Microphones and also founded DBX, argues in a recent Studio Sound article that for accurate sound reproduction, a system must be able to reproduce at least 40kHz. Starting with the perspective that human hearing is a survival tool, he says, "Human hearing is generally, I believe, misunderstood to be primarily a frequency analysis system. The human hearing system uses waveform as well as frequency to analyze signals. It is important to maintain accurate waveform up to the highest frequency region with accurate reproduction of details down to 5μs to 10μs. To fully meet the requirements of human auditory perception I believe that a sound system must cover the frequency range of about 15Hz to at least 40kHz (some say 80kHz or more) with over 120dB dynamic range to properly handle transient peaks and with a transient time accuracy of a few microseconds at high frequencies and 1 ?-2 ? phase accuracy down to 30Hz." (Check the Earthworks site at for more from DB, or go directly to for the full text of the Studio Sound article he wrote.)
For what it's worth, as Rich and I tested these units we felt that we could hear definite improvement of audio quality and feel at 96k. It seems clear that this is where the future systems will be going as computers get faster and hard drives get bigger and cheaper. If you're looking for the absolute best audio quality I'd recommend getting a 96k interface so that as your studio and system grows, it can keep up. Of course if what you're doing is recording punk rock or digital hardcore music and you're on a budget, this is pretty much a non-issue. Most of the people I spoke with thought the 24 bit 48k interfaces sounded really excellent for just about any application.
Another issue to think about is whether you want to assemble your system yourself or pay someone else to do it. Tape Op is all about DIY, but if you hate dicking around with computers or aren't very familiar with them, you may want to consider the pre-assembled route. At least then, you'll be starting with something that works and can ease your way into the land of computer geekdom. (I'm pretty good with computers, but if I decided to buy a PC, I'd do my best to avoid having to hook it all up. PCs are a bitch to configure and troubleshoot. That's why I think Macintoshes are better.) Wave Digital for instance will sell you a PC that has the interface and recording software of your choice all installed and ready to rock. All of the device managers are optimized for recording music, they burn the computer in and you also get a back up CDR that can restore your entire system in the event of a crash. A 500mHz Pentium machine with 64 megs of RAM and a 10 gig hard drive along with Cubase and an M-Audio 4 in/4 out interface is $1899 ready to go. Sweetwater Sound is also an Apple VAR (Value Added Retailer) and they will put together a complete system, including the computer, configured to your needs, with the cost of assembling and testing the whole setup kept very minimal. They can also configure and install software and hardware into your PC as well. If you do decide to do it yourself, and most of you will, be sure to buy stuff from a dealer who really knows what they're doing. Computers and Music has been specializing in exclusively, well, computers and music since 1982. Their website is the most extensive I came across on this subject while researching this article. They're extremely knowledgeable and can help you configure the system you need. (I know this sounds like a promo plug, but I've been a customer of this place for over 15 years.) I also spoke with Mark Pierucinni who has configured systems for people like Peter Gabriel and some of the vendors above. Freelance consultants like Pierucinni will help you put together and even tutor you on a system without any bias towards a manufacturer who pays them or gives them commissions. He is even enough of a geek to have tested several different video cards to see which ones refresh the screen fastest while simultaneously playing back music. Wherever you end up buying from, just make sure they have good, solid technical support because at some point, you'll need it. You should of course call at least two or three different dealers and/or manufacturers to not only research price, but to get a feel for how much support you can expect after you've bought something.
We tested as many interfaces as we were able to get our hands on and then talked with some of our friends about some of the interfaces they were using. Rich Hardesty did most of the testing, using a Pentium II, 400mHz, with 128MB RAM a Maxtor 7200RPM UDMA-33 hard drive running Win 98 on the PC side. After he tested the cards on his PC, I hooked them up to my Power Mac G3 (The old beige kind) running at 233mHz with system 8.6 with an old 2 MEG SCSI hard drive. Unless there were problems on the Mac, most of the comments are Rich's. Here's the results.
