Expert Advice

Aug 1, 2000 12:00 PM, Mike Levine

Welcome to "Operation Help." This month, we'll concentrate on answering reader questions. Topics covered include noise-reduction formats for cassette, analog recording, and M-S miking with PZMs. If you have a gear or technical question, please e-mail it to us at emeditorial@intertec.com.

QUESTIONS FROM READERS Rub-a-Dub-Dub Q:I'm in the market for a dubbing cassette deck (my old one just died on me) that I want to use to duplicate my demos. I need some help with the noise-reduction options. What is HX Pro and is it better than Dolby B or C? What would be the best type of noise reduction for applications where I'm sending the tapes to people with different types of decks?

David Parise via e-mail

A: Actually, HX Pro is not a noise-reduction format in the strict sense of the term. Instead, it's a process that Dolby developed to enable hotter signal levels to be recorded to tape with less distortion and better high-frequency response. By recording a hotter signal, you end up with a better signal-to-noise ratio, so using an HX Pro-equipped deck can result in tapes that are less noisy.

As for Dolby B and C, the important thing to remember is that you want the cassettes you send out to be compatible with the machines that they'll be listened to on. Therefore, given the choice between Dolby B and Dolby C, you would probably want to choose B-even though it's inferior to C-because it's a much more universal format (this is especially true when it comes to portable personal stereos). If it were me, I'd eschew noise reduction entirely (I've found that tapes recorded with noise reduction on one cassette player don't always sound right when played back on another cassette player) and simply record my cassettes with as hot a signal to tape as possible (preferably with an HX Pro- equipped tape deck).

Before purchasing another deck, you should also be aware that dual-cassette machines rarely offer the same recording quality as a good single-cassette deck. So if you really want to stay with the cassette format, you might consider replacing your defunct dual deck with a pair of single machines.

However, before you invest more money in cassette decks, you should seriously consider putting your final product on CD instead. Yes, it will cost you more in the short run, but the improvement in sound will be dramatic. And with so many musicians putting their demos on CD, do you really want to continue to send out cassettes?

If you have a computer, you can purchase a CD-R drive for relatively little money and burn your CDs from that. And if you don't have a computer, stand-alone CD-R decks are available from a number of manufacturers. There are even products, such as the AudioWrite Pro from Microboards Technology (see Fig. 1), that function either with a computer or as stand-alone units.

You didn't mention what type of deck you were mixing down to, but if you need a digital mixdown deck in addition to a CD burner, you can get units-such as the Alesis Masterlink-that handle both functions.

For a more detailed rundown on the various CD-R and mixdown decks on the market, I recommend you take a look at EM's 2001 Personal Studio Buyer's Guide. Check both the "Digital Mixdown Machines" and "CD Recorders" categories.-Mike Levine

Analog Angst

Q: I'm a music student at a small university in eastern Texas, and for the past eight months I've been working off and on with our music department's Tascam DA-38 multitrack recorder. I think that I've gotten the hang of the small setup I use, and I consider myself at least proficient (definitely not professional yet!) at multitracking. However, I've been asked to help a small recording studio in town get restarted after a five-year hiatus. I don't think that they're able to buy any new equipment right now, so they want me to work with what they have. This studio was built in the mid-'80s, so it's basically analog city! The equipment that they do have is nice but not amazing, and I think that I can handle most of it-with one exception. They use a Tascam reel-to-reel 8-track. I must say that that kind of threw me. I'm really in need of some resources to help me learn more about this. Can you recommend anything to me, either books or Web sites? Thanks a lot for your time.

Stephen Adams via e-mail

A: Although you're dealing with analog by necessity, a growing number of musicians have switched back to it by choice. Many would cite analog's warmth as a reason they prefer it over digital. I, too, like the sound of a great analog deck that's been tweaked to within a few angstroms of its life, but the care and feeding of such beasts is not without expense (look at the price of a reel of 2-inch tape if you want a reality check).

Here are a few retro tips for you that should get you going. First, for an analog deck to sound as good as possible, it needs to be recorded at a much hotter VU level than a digital deck. Contrary to digital, where there is no life above 0 VU, a good analog tape can be pushed anywhere from plus 4 (+4) to plus 8 (+8) above 0 VU on the meters (depending on the machine's calibration and the type of tape being used). Tape saturation gives you a nice, soft compression, which helps smooth out the transient peaks as well as add those nice, fat distortion by-products that help give recordings a fuller sound. And since there is a somewhat limited signal-to-noise ratio on analog tape (remember, it works by pushing rust past magnets), making the "signal" part louder keeps the "noise" further down in the mix. Many engineers also choose to use additional noise reduction, such as Dolby SR or DBX, for analog recording.

As for reference materials about analog recording, you might want to start with Tom Lubin's book Shaping Your Sound with Analog Multitrack Recording, which is available at www.mixbooks.com. There's also some cool stuff on my new Web site (which, coincidentally, features columns from both Eddie Ciletti- now with Mix-and myself, among others). We've put up test tones both for tape alignment and guitar tuning. So now when you need to tune your ax or check your analog deck in the middle of the night, you can download the needed tones in a few seconds and get rockin'. Try it out at www .modernrecording.com/resources/tones.shtml. Eddie has added some alignment procedures to the test tone section, so that should get you started.-Mike Sokol

Back-to-Back, Belly-to-Belly

Q: I had a sudden inspirational flash regarding mid-side miking procedure. I thought I would float it past you for consideration, critique, etc. Not having a figure-8 mic for the side component of the matrix, would it be possible to use a pair of Realistic PZM mics back-to-back (perhaps with a Perspex sheet sandwiched between the two mics to increase isolation between their respective pickup fields), then phase-reverse one of the PZMs and feed it, together with the other normal-phase PZM and forward-facing cardioid, into a mixer for summation in the usual M-S fashion? I suspect the PZMs would not strictly sum together to fully approximate a figure-8 mic, lacking a true 90-degree dead zone, but how close do you think they would get to this ideal?

The back-to-back on a Perspex sheet array is often promoted as a good basic orchestral stereo-miking technique, hoisted above the conductor's head and perpendicular to the orchestra; this is simply an elaboration on that to make it M-S: of course, one would plan on getting the mid-cardioid mic as close as possible to the side array. Any reflections on this proposal?

Ray Thomas via e-mail

A:Yes, you can put a pair of PZM mics back-to-back on a 2-by-2-foot sheet of Plexiglas and make them act like a single figure-8 mic by summing them together with their polarities reversed.

I brainstormed with Bruce Bartlett from Crown about using PZM mics for mid-side applications. We concluded that it's possible to use the same pair of PZM mics as both the figure-8 side capsule and the omni "mid" capsule. Basically, by splitting the signal among four input strips on a mixing console and summing them together-both in-phase to create an omni-pattern mic, and out-of-phase to create a figure-8 mic-you can make a variable-pattern mid-side mic.

According to Bruce Bartlett, "You can create an omni-mid/bidirectional-side M-S microphone by mounting two PZM mics on either side of a large boundary, such as a 2-by-2-foot panel. Aim the edge of the panel at the sound source. Now you have a left-aiming PZM and a right-aiming PZM that are virtually coincident" (see Fig. 2). You can also create a mid and side signal from these two PZMs by using Y-cables, a polarity reverser, and a 4-input mixer (see Fig. 3).

It's also possible to matrix a pair of back-to-back PZM mics into a mid-side mic pair because the in-phase summed signals make an omni pattern, while the out-of-phase summed signals make a figure-8 pattern. This mid-side signal is then fed to a second mixer, where the side information is mixed to stereo with a polarity-reversed channel on one side. The "mid" signal is fed to both the left and right channels in-phase, via the pan pot (see Fig. 4). Of course, this can all happen in a single mixing console if you have enough subgroups to mix to.-Mike Sokol A