Convergence Corner


December 1996

This month: Convergence?, CD-R Problems, FREQ for cheap spectrum analysis.

It's time for a trip into industry buzzword land. Convergence is one of those words that gets thrown around a bunch by the press in almost all the fields I read literature from. The basic idea is that all of these high-tech toys we play with are going to merge together. Our computers will join with our audio system so seamlessly that you control the whole thing equally well with either remote or keyboard. The same monitor we use to surf the web will be equally adept at tuning in TV. The current wave of convergence comes in a couple of forms. Multimedia combines typical computer titles with real video and audio capabilities. Home Theater connects TV and video together with multi-channel audio. You get the idea.

Here at Soundstage!, we like to think we know something about high-end audio. And as a magazine only available via the WWW, we have to figure our readers know more about using computers than your average person. All these things are crashing together, with current common denominators like the compact disc. Convergence Corner is going to be a place for me to talk about what's possible right now by combining these technologies, with the audio/computer interface being the main focus. This is not the "What's happening with DVD?" junk that passes for tech coverage in some more mainstream publications. I want to talk about things you can do now, not extrapolate some grand future vision. We're going to talk about the ugly technical details of how to really use the products that you can go buy (or download) today.

CD-R Leaves My Edge Bleeding

If you've been reading Soundstage! a while, you may remember the long-winded discussion of my initial foray into recordable CD territory. An updated version of that whole document is available. Let's catch up with what's happened since then. At the end of that, I had successfully configured my Yamaha CDR-100 so that I could create both data and audio CDs with Adaptec's Easy-CD Pro software, encountering some limitations that I could work around and others that seem impassable with the current technology.

That level of contentment lasted about two months. After I'd cut about 15 discs, my CD-R drive apparently had enough and dropped dead. One day it was working like a champ, the next it would eject anything I put into it following an ugly reading session. Those grinding noises that were coming out of the mechanism were not a good thing. Back to the reseller I bought the drive from it went, for them to pass it along to Yamaha for repair. This turned into a long complicated process, where the ball was dropped by seemingly everyone involved. It took me two months to get a replacement player back. The new one is working just as well as the old one did, and it's been going well enough that I find myself needing a lot more blanks. I've been in contact with a number of other CD-R owners since then, and have come to the conclusion that what happened to me is in fact approximately the average experience, rather than a rare stroke of bad luck.

Lessons to learn from this escapade? There's a few. First, don't expect that your investment in CD-R is going to leave you with the non-stop capability to create your own discs. If you really need to count on that, you need to buy at least two drives so you have a spare for repair downtime, because even under optimal conditions they need to get recalibrated occasionally if nothing else. Second, do everything possible to avoid putting wear and tear on your drive. My current model is that the only thing I put in the drive are blanks that I'm about to burn. No reading anything, no putting dusty old stuff from my audio collection in there. It used to be that I needed to read all the tracks I wanted to write first in the CD-R drive itself, but I've worked around that limitation. Currently I'm using the CDDA program that comes in the package to read audio tracks to my hard drive; I grabbed mine from (note that this is a DOS program, so search accordingly). I'll be looking at other programs that serve this purpose as well in the future, as I'm not totally content with this freebie solution. As a side note, if you're going to be doing serious audio extraction, I recommend that you get a Plextor CD-ROM drive to go with your CD-R. Plextor appears to be the only manufacturer that is taking proper care to give good audio performance out of their drives. Other drives do silly things like slowing down to single speed on audio reads, or have unreliable placement on the disc when told to seek to the beginning of a track. Some of this you can correct with good software, but you shouldn't have to. One warning is that the very high-speed drives even from them can have minor problems reading audio at extreme speeds; I don't recommend going over 4X speed even if your drive can read 6X, 8X, or 12X.

There are some other things to consider that will extend the useful life of your CD-R drive. I've got an internal drive, because it fits easily in my huge tower case without any problems. I will no longer recommend doing this. The external models have a number of advantages. You can turn them off easily when not using them, which cuts down on turn on/off surges and just plain makes everything last longer. The drive is outside of the heated, dusty soup that is the inside of computer cases anymore. I have settled on no less than 5 fans inside my case before I was happy with how everything was cooled, and there's still too much dust inside. Finally, you can move external drives out of the way to minimize vibration. Currently, I don't do anything more violent to my computer than rolling it small distances on its wheels with the drive inside. If I need to put it on its side to work on the motherboard, or move it to another location, the CD-R drive gets yanked out of it first and moved as delicately as possible, separate from the manhandling that the big case needs. This is a real pain for me; with an external drive, it would be easy.

I don't know which, if any, of these factors contributed to the demise of my first drive, but I'm taking no chances now. The Yamaha drive is still the only one I'd buy for audio applications. The horror stories I hear about the cheap stuff from HP and Phillips keep me far away from the $500 bargain basement specials I see on those drives.

FREQ Tells All

Confession time: I own an equalizer. There, I've said it. See, in audiophile circles, using an EQ is an unpardonable sin that is considered to reduce the fidelity of your system to approximately the same level of performance as your average 8-track player. I happen to agree with this; any equalizer I've ever heard that was good enough that it didn't totally destroy the sound that was passed through it cost so much that you could have bought equipment that didn't need to be filtered with the money instead. Truth is, I use my equalizer for one purpose only--to watch the bouncing display. The light show gives me some useful feedback on the frequency spectrum of the music I'm listening to, and I get an idea of things like exactly how deep the bass I'm hearing actually is. Problem is, that display isn't nearly adjustable or detailed enough to satisfy.

Well, I've got this big stack of computer equipment that has all kinds of fancy capability, including sound processing, so you'd think that could help. I've found the holy grail of bouncing frequency spectrum displays, and it's called FREQ. If you can use DOS programs, go grab a copy of from somewhere like now and start playing. There are copies for other systems in that archive as well, like Linux and Sun, and supposedly it will run under some Windows combinations (I know it chokes with NT).

The basic operation of the program is that it constantly samples whatever data is moving through your sound card, performs a Fast Fourier Transform on that that to get a frequency spectrum analysis, and plots the results. So anything you can play through your sound card, you can sample with it if you can figure out how to run it at the same time as the program. What I do is fire up my CD-ROM drive with an audio CD, then run FREQ. Instant graphic display of the frequencies present in that music.

Before you try and use it heavily, print out a copy of the documentation. It will save you endless time when you’re inside the program. The basic command interface uses the keyboard to toggle options among the series of allowed inputs, along with some things that you enter values in for. What frequencies you see a display for is a complicated function of the sampling rate, the FFT length, and all sorts of other things. There is a FREQ.INI file that lets you configure the program all at once; there’s a command within the program that saves the current state you’ve put things in over that file, which is the easiest way to get just what you want every time you start the program. I don’t recommend saving over the default INI file until you’re very familiar with the program, as some of the damage you can do to the default settings can be difficult to reverse.

To get a good display of bass content, I set the sample rate to 10000, the FFT length to 2048, the reference frequency to 1000, the base frequency to 13.4747, and the frequency factor to 1.41421. These odd numbers come out of the math behind the frequency transformation, which you don’t need to understand to use the program (but it does help). Just fooling around until you get a display you like is a valid way to approach the program.

There are some other features to investigate while you’re at it. You can configure things to enable an averaging decay mode, where old samples hang around for a bit instead of fading right away when new ones arrive (this is similar to the peak hold you find on some EQ units). This slows the action down enough that you can see what’s going on. The program will even tell you where the frequency peaks in your music are at by itself, without you needing to squint at the display.

I’ve found a bunch of applications for FREQ since I first started using it. It’s great fun to take that favorite CD of yours, the one with the huge bass notes, and see exactly what frequency the bass is actually playing at. This lets you walk into your audio dealer, request to hear something, and say "that drum has solid output down to 27hz". When they look snide and ask how you know, tell them you have a computer frequency analyzer that you check all your music out with. Use a haughty tone, like everybody has one of these and he’s asking a stupid question. But enough of my condescending dealer handling tips.

The program also solves one nagging problem I’ve been fighting for a while. When feeding output from my turntable through the A/D converter in my sound card when making a CD-R, I need to set the input level and gain so that I get maximum resolution without overloading the converter. FREQ has this feature where the screen will flash whenever there’s an input overload. Since I do all my analog recording under DOS anyway, this makes it easy to switch between the level setting program, FREQ, and the recording utility to make optimum LP transfers. The gain should be as high as possible without seeing any distortion flashing.

The most fun thing to do with the program is run a cable from a tape output on your stereo and connect it to the line input on your sound card. Start up FREQ, and you get a running display of everything you listen to bouncing in time with the music. Now that’s convergence for you.