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24X CD-RW drives square off

Two 24X RW drives square off

A look at the drives from the front. . .

. . . and a look from the back

The two drives are the Plextor PlexWriter24/10/40A and the QPCDRW241040i by QPS, Inc. (which appears to be a rebadged Sanyo CRD-BP1500P). Both are ATAPI drives claiming speeds of 24X CD-R burn, 10X CD-RW burn, and 40X read. Both drives feature Sanyo's BURN-Proof technology to prevent buffer underruns, as well as Z-CLV recording (more on that in a moment). Looking at the features, the drives seem pretty comparable to one another, but we'll see how they perform under pressure.

If you're very familiar with CD-RW drives, you're almost certainly familiar with Plextor. Many will contend that Plextor makes the best CD-RW drives around, bar none. The 24/10/40A comes in a nice retail box with an ATAPI cable, mounting screws, a manual eject tool, and one each of CD-R and CD-RW media. The software bundle includes Adaptec Easy CD Creator and DirectCD, as well as Plextor's PlextorManager2000 software, which includes a disc duplicator and digital audio extraction program, among others. Documentation includes a fold-out installation guide, an Operations Manual, and a Users' Guide for the PlextorManager software. Currently, the PlexWriter goes for as low as $151 on Pricewatch in retail form.

Compared to Plextor, QPS is a brand that you probably haven't heard of before; I know I hadn't. The drive comes in a retail box that included an ATAPI cable, mounting screws, an audio cable, and one sample of CD-R and CD-RW media. An instruction manual is also included. The software bundle features Nero Burning-ROM and Nero InCD. I actually purchased the drive due to a mixture of curiosity and frugality; I happened to find it on sale at CompUSA for $99 after rebates. Currently the drive costs $129.99 from CompUSA, either by mail-order or in a retail store. At the time I purchased the drive, the lowest one could find a PlexWriter24/10/40A was around $200; needless to say, I was curious how my "bargain" CD-RW drive would compare.

As a point of reference, also included in the tests Plextor's 12X PlexWriter. With the advent of these new drives, we'll see that twenty-four isn't necessarily twice as much as twelve; the 12X results keep the real-world performance in perspective.

You can see from the picture that Plextor hasn't changed the look of their drives much between the 12X and the 24X. The 24X does have a small cooling fan in the back, however, an addition we first saw with their 16/10/40A drive. By way of comparison, the QPS drive looks kind of, umm, iMac-y, with a face made of frosted clear plastic.

I can defend myself here on two fronts: one, it was cheap enough that I could put up with some clear plastic, and two, the picture on the box didn't look like that. I didn't know, I swear!

The back of the QPS drive has vent holes that look like they'd have a cooling fan behind them, but there isn't one, at least not that I could see looking through the vents.

Marketing terms galore
Along with the higher speeds, these drives feature some technologies you might have heard of before, as well as some new ones. Before we move on to the benchmarks, it's important to understand how these drives work.

BURN-proof explained
Not being one to duplicate a previous effort, the following four paragraphs in this section are shamelessly ripped from my PlexWriter 12/10/32A review.

BURN-proof (short for Buffer UnderRuN—yeah, it's a bit of a reach) is a technology designed to prevent the dreaded buffer underrun during the CD recording process. Let's start with a brief discussion of what buffer underruns are and why they occur.

When burning a CD-R, once the burn process begins, the data has to be laid down onto the disc from start to finish without any interruptions. If the data source (typically a hard disk, but possibly a CD-ROM drive in the case of a disc-to-disc copy) can't supply data quickly enough for the CD-R drive, a buffer underrun occurs and the CD-R drive basically runs out of data to put on the disc. At this point, the disc being burned is "coastered" (because it has no use as anything but a drink coaster, get it?), and you have to start from scratch.

Typically, hard drives are significantly faster than CD-R drives, so what's the problem? Well, in a multitasking environment, there's always the chance that another task will eat up enough CPU time and/or hard disk access to cause a buffer underrun. For this reason, many people start a disc burning and then back away from the computer slowly and tiptoe out of the room, afraid to do anything else on the machine for fear of a buffer underrun.

Sanyo's BURN-proof technology aims to fix this problem. I'll summarize briefly; if you want more information take a look at this page at the BURN-proof website. In fact, go look at it anyway because the illustrations are just hilarious. Anyway, BURN-proof allows the drive to turn the laser on and off during the recording process. If the data stream dries up during recording, the drive simply turns off the laser and waits in a holding pattern until more data is available. When there is more data, it figures out where it left off, turns the laser back on, and starts recording again. Pretty slick.

As mentioned previously, both of the 24X drives in this review have the BURN-proof feature, so you shouldn't have to worry about coastering any discs due to buffer underruns with either drive.

Z to the C to the . . .

A Sanyo illustration of the Z-CLV process

Now that BURN-proof is covered, let's talk about Z-CLV, or Zone-CLV, recording. Z-CLV divides the disc into several zones during the recording process. The first zone (the inside of the disc) is recorded at 16X. The middle zone is recorded at 20X, while the last (outer) zone is recorded at 24X. The technology takes advantage of the fact that, if rotational speed remains constant, the rate at which data can be read or written rises as the laser moves from the inside to the outside of the disc. By raising the write speed as the laser moves to the outside of the media, overall write speed goes up without needing to raise the rotational speed of the media. This is important, because the faster the media spins, the more chance that vibration and other factors can complicate the recording process.

As you have probably already guessed, while Z-CLV recording does enable these new drives to achieve higher write speeds overall, it also means that these 24X drives always start recording at 16X, and only achieve their rated write speed at the outer portions of a disc. If you are only recording a small amount of data to a CD-R, it is likely that the drive will never achieve its rated 24X speed.

Given that the drives don't record the entire disc at 24X, it seems obvious that they're not going to write a disc in half the time of a 12X burner, in spite of what the ratings may imply. This is why including a 12X drive in our tests is useful; it shows how the Z-CLV "speed stepping" affects the overall write time.