Expert Advice

Apr 1, 2000 12:00 PM, Mike Levine

Welcome to "Operation Help," the column dedicated to helping you get more out of your gear. This month we offer advice from Emagic on setting up groove templates in Logic Audio, from GT Electronics on omnidirectional miking, and from Sonic Foundry on getting more from Acid software. We also get tips from an electronics expert on minimizing the effect of radio frequency interference on audio gear.

FROM THE MANUFACTURERS Setting up Groove Templates in Emagic's Logic Audio In addition to extremely stable timing, Emagic's Logic Audio Platinum and Logic Audio Gold feature some of the most extensive and musical groove functions available on the market today. The real-time, nondestructive nature of the program is extremely effective for creating, editing, and auditioning MIDI groove templates that you've generated, imported, or extracted from digital audio. You can create MIDI groove templates in Logic Audio in one of the following ways:

1. Select any existing MIDI sequence that you wish to use as a MIDI groove template. Select Make Groove Template (Options 8 Groove Template 8 Make Groove Template).

2. Record or step enter one bar of 16th notes. Modify the positions, Velocities, and note lengths until you have the groove or feel you want, then select Make Groove Template.

3. Import a Cubase DNA groove.

4. Within Logic Audio's integrated stereo Sample Editor, extract the groove from any digital audio region using the Digital Factory's Audio-to-MIDI Groove Template feature.

Most sequencers' groove templates contain only note-position information, which determines the rhythm and feel of the sequence. In Logic Audio, the templates also contain Velocity (accents) and note-length (articulation) data. This is crucial to the accurate reproduction of a groove.

Logic Audio's extended sequence parameters (Options 8 Arrange) offer extensive parameters for quantizing MIDI sequences nondestructively. After you have quantized a sequence with a groove template, you can edit the following extended parameters in real time while you listen:

1. Q-Strength. This adjusts the percentage of quantization that the selected MIDI sequence will receive. The default setting is 100 percent. Lowering the percentage will move the notes in the sequence farther from the groove template's note-position grid, thus "loosening" the feel. Zero-percent Q-Strength will remove all quantization.

2. Q-Veloc. This adjusts the amount of the groove template's Velocity envelope that is imposed on the selected MIDI sequence. When Q-Veloc is at 0 percent (the default setting), the notes in the sequence will play back at their original Velocities. At 100 percent, the selected sequence will have exactly the same Velocity envelope as the groove template.

3. Q-Length. This adjusts the amount of the groove template's note-length information that the selected MIDI sequence will contain. At the default setting of 0 percent, note lengths in the selected sequence will remain the same. When you increase Q-Length to 100 percent, the selected sequence will have note-length information matching that of the groove template.

All these edits affect only playback and are totally nondestructive. You can massage the settings in real time and the results are immediately audible. This is a primary strength of Logic Audio's real-time functionality. It's a very musical but often overlooked feature.

Here's the kicker: once you've added a groove template to one or more MIDI sequences, you can edit that groove template in real time with the Matrix, Event, Score, or Transform Editor. Any edits you make will affect (in real time) all the sequences using that groove template. This feature is called the Living Groove Connection.

Here are some power tips:

1. Name your sequence before using the Make Groove Template function. The groove template is then added to the bottom of the quantize selection list in the MIDI Playback Parameter and Extended Sequence Parameter windows.

2. Copy your groove templates for variation.

3. In your Autoload's Arrange window, store groove templates in a folder named Grooves.

4. Investigate and learn how to use the Digital Factory's Audio-to-MIDI Groove Template function.-Clint Ward, Emagic

Omnidirectional Miking Tips from GT Electronics An omnidirectional microphone picks up equal sound energy from all directions. The polar pattern is, in theory, a perfect circle, although in practical application this is difficult to achieve. Because of this polar pattern, the signal includes both the direct source and the reverberant sound reflecting off the surfaces in the room. You must choose your mic placement carefully to achieve the right blend.

The closer the microphone is to the source, the more distinct and present the sound will be. The farther it is from the source, the more diffuse and less clear (but more spacious) the sound. The distance at which direct sound and ambient reflections are equal is called critical distance. Be aware of critical distance when you're deciding on mic placement. With an omni microphone, follow the three-to-one rule. For example, if the room is ten square feet, the mic should be within three feet of the source.

Omni microphones are a frequent choice for stereo-miking or room-ambience applications, but they are often overlooked as instrument mics. The new GT Electronics AM30 and AM40 microphones have midsize (3/4-inch) diaphragms with interchangeable capsule designs, allowing you to easily change from the supplied cardioid capsule to a supercardioid or omnidirectional capsule. Here are a few omni capsule secrets to help you get the most out of your new (or existing) omnidirectional microphone in a close-miking application:

1. Omni microphones typically exhibit a smoother, more linear response than other types of capsules.

2. Unlike directional microphones, omni microphones are immune to the proximity effect, the increase in a mic's low-frequency sensitivity when it's placed very close to an instrument.

3. Omni mics commonly have higher outputs (4-6 dB) and better signal-to-noise ratios than mics with other patterns.

4. Because of their gradient pressure sensitivity, omni mics are not as susceptible to wind noise, which makes them a good outdoor miking solution.

With these unique properties, an omni microphone can be an outstanding choice, yielding exceptional (and sometimes surprising) results as a close-instrument mic. On acoustic guitar and other stringed instruments, the absence of the proximity effect and the mic's linear response allow for close miking without the "boominess" you often get when miking near the sound hole with a cardioid or other directional pattern. Saxophone tones can also benefit from an omni pickup; try miking closely with an omni mic if your brass tracks are honky, nasal, or pinched-sounding.

Of course, omnidirectional mics have their own set of placement and dynamic considerations. Here are several things you should keep in mind:

1. Omni mics are more responsive to low frequencies.

2. Because they pick up sound from all directions, omni mics are more likely to register the rumble from air conditioners and heaters.

3. When you use omni mics outdoors, close placement is necessary to prevent picking up too much ambient noise.

4. To avoid excessive bleed, be careful when placing omni mics relative to other instruments.

With these tips, and some practice, you can make the most of your omni mics.-Randy Neiman, GT Electronics (a division of Alesis)

Getting More out of Acid If you own a PC and are into loop-based music production, you probably use one of Sonic Foundry's Acid software products. Following are six quick tips to help you get even more out of Acid. Except where otherwise specified, these tips apply to all titles in the Acid software family.

1. Acid-izing one-shots. Acid assumes that most WAV files are 4-beat loops. That can be annoying if you want to work with an existing library of one-shot WAV files, such as individual drum samples. A freeware utility called Acidizer (www.xaviersjoint.com/acidizer.htm) will make WAV files recognizable as one-shots to Acid.

2. Easy tool swapping. You can quickly cycle through the Acid tools. Press D to cycle forward, and Shift+D to cycle backward.

3. Slip 'n' split. For an easy variation on a track, try splitting an event (S is the keyboard shortcut for the Split function) and then holding down Control and Shift while dragging within either of the newly split segments. The event stays where it was, but the audio data "slips" backward or forward, resulting in a quick shuffle or syncopated fill.

4. Dragging drumrolls. Add a volume envelope (volume envelopes are not supported in AcidXpress) to the event you're editing, pick out a drumbeat, and split just to the left of it. Select the Draw tool, then hold down Control while dragging and dropping copies of the beat, thus creating a drumroll. For a more even-sounding roll, snap to 16th or 32nd notes. You can add a crescendo to the roll by increasing the volume envelope slightly for each new event.

5. Painting plaid. The Paint tool works like Bugs Bunny's can of plaid paint-no matter how sloppily you paint in the events, the loops always line up with the grid. The Paint tool also affords easy access to the Erase tool (via the right-hand mouse button), which behaves in the same way. If you deselect Enable Snap To (F8), you can splotch together elaborate cut-up variations on a loop while keeping the original rhythm intact.

6. Ping-pong panning. Paint in a long event and add a pan envelope to it (AcidXpress does not support pan envelopes). Duplicate the track, then pan one track completely to the left and the other to the right. Next, use the Erase tool to chop out alternating bits of the audio, giving it a rapid-fire stereo movement.

Also try bouncing between two different FX envelopes (only Acid Music 2.0 and Acid Pro 2.0 support FX envelopes), or changing the pitch of the duplicated track using the track header's Pitch Shift shortcut menu.-Frank Shotwell, Sonic Foundry

QUESTIONS FROM READERS RF Predicament Q: I live near a 100 kW FM radio station broadcasting on 92.3 MHz. Many appliances in my house pick up interference from the station, but particularly bothersome is the radio frequency (RF) interference that my telephones and musical equipment pick up. For example, my music system receives the radio signals in the line between the amplifier and speaker. I have tried a number of tricks, including shortening the cable, wrapping it around toroids, creating loops and kinks in it, rerouting it, using heavy-gauge Monster cable, and (per the recommendation of the station's chief engineer) inserting a 47 pF capacitor across the volume control to ground. Some of these tricks help, but nothing snuffs out the interference altogether. Is there a way to design and install a lowpass filter that will effectively eliminate the broadcast interference while not significantly affecting my sound quality?

Steve Poteet via e-mail

A:To answer your question, we consulted Peter Miller of CAE Sound in San Mateo, California. Miller is an electronics expert who has designed and repaired gear for the Grateful Dead and other major acts. According to Miller, installing lowpass filters and other modifications might help, but it's probably not a cost-effective solution. "It would be cheaper to replace your gear," he says, "or even move to another location." He further points out that living in such close proximity to heavy amounts of RF could pose a health risk.

If you're planning to stay in your present location, however, Miller has some suggestions on how to deal with the problem. "Basically we're looking at a couple of techniques to combat RF energy. Put all of your gear in a steel equipment rack. Get a rack that has front and rear doors so that you completely isolate your equipment from the radio noise."

It's also very important, he says, to be sure that your equipment is properly grounded. Making the switch to balanced gear would help a great deal, as well. "Consumer hi-fi equipment and low-end, unbalanced audio equipment is much more susceptible to this kind of problem," explains Miller. "If you really want to beat that RF interference, you'll have to jump into the professional, balanced world with as much of your equipment as possible."

Miller recalls a friend of his who lived near a radio tower and had a similar problem. "It seemed that his speaker wire was picking up radio noise. He even went so far as to put the speaker wire inside steel electrical conduit to shield it."

Finally, Miller suggests that you find out whether the radio station's transmissions are exceeding the legal limits. "One question that remains unanswered," he says, "is whether the transmitter's field strength is acceptable to the Federal Communications Commission."-Mike Levine