Variations of the typical podium mic can also be applied as choir mics and instrument mics.
By Gary Parks, November 12, 2015
Though podium mics may be less widely used for sermons and other presentations than in the past because of the ready availability of headsets and wireless systems, they are a useful and flexible means to capture a presenter’s voice when working from a lectern or pulpit. With their integral goosenecks, variations of the typical podium mic can also be applied as choir mics and instrument mics. Podium mics are designed to be used from a distance of several inches away, and will allow the presenter or musician some latitude of movement without a great change in the level and tonal quality of the audio.
DPA is well known for premium-quality, small-format condenser microphones—widely used in pro audio for instrument and vocal mic’ing applications. The DPA d:screet SC4098 gooseneck podium mic
is a relatively recent addition to the genre, as part of the company’s d:screet microphone line. This mic continues the tradition of excellence.
The d:screet SC4098
is named for the particular miniature supercardioid condenser microphone element that it employs, and is available in several lengths and configurations. The d:screet SC4098-BX30 test model features a 30 cm (approximately 12 inches) gooseneck that is flexible on the top and bottom approximately one-inch, with the remainder of the length being solid. Each of these joints can be bent with little effort and virtually no noise approaching a 90-degree angle in any direction, offering very versatile positioning, yet staying in place with no droop or shift even if shaken or bumped. The gooseneck itself is slim, at less than one-quarter inch in diameter. The base of this model is a two-inch-long barrel ending in an XLR-3M connector to plug into a connector socket on the podium or a mic cable.
The business end of the microphone is approximately the same diameter as the gooseneck it is attached to, shielded by a removable windscreen. Removing the windscreen, you’ll see something different than the usual. While the microphone element itself is tiny, a narrow black tube extends about one inch beyond it. DPA calls this technology an “interference tube,” which the company has used to great advantage in many of its professional mics.
Why an interference tube?
The key purpose of the interference tube is to increase the directionality of a microphone element, while maintaining flat on-axis frequency response and consistent off-axis response. Increased directionality, combined with good off-axis rejection, allows the microphone to isolate what you’re trying to pick up while attenuating sounds from the sides and rear—and ideally promoting higher gain before feedback. DPA has been researching and perfecting this technology for the past 15 years.
According to DPA’s Mikkel Nymand, a tube with a specific length and density is placed in front of the mic diaphragm and is covered with a protection grid with slots cut along the side. Sound coming from directly in front of the mic is unimpeded, while sound coming from any other direction has different path lengths creating desirable wave cancellations within the tube, and resulting in the elimination of most of the off-axis sound. The trick is, through the choice of materials and the specific design of the tube, to have the on-axis response be accurate, while the frequency response within the mic’s coverage pattern remains smooth and consistent at the sides, and sound coming from the rear is well attenuated. DPA also uses interference tube technology in its d:vote 4099 instrument microphone line, and several other models.
Testing the d:screet SC4098 Podium Mic
I first tested the podium mic in isolation using headphones and a monitor speaker in a smaller room to experience its audio quality and coverage pattern, and later in a sanctuary to see how it performed in a larger room with a loudspeaker cluster overhead. Speaking into the mic on-axis from six to eight inches away, the sonic character was quite smooth and natural, with full-sounding response to the lower frequencies of my voice, distinct reproduction of consonants, and a nice but not exaggerated sibilance. It sounded like a very good handheld condenser mic when placed a few inches back from the mouth. Via the headphones, I moved three feet or so away, and still had a full, natural response (one variant of the microphone is the 4098H hanging choir mic, so this result is consistent with that application). Frequency response at a distance of 20 cm (about eight inches), per the specifications, is 100 Hz-15 kHz, with a 3-dB soft boost from 8-15 kHz.
The off-axis frequency response at 45 degrees or so seemed consistent with on-axis, and with little change in level; the published polar plots confirm this finding. Even if a presenter moved side to side a bit while talking, listeners would not be likely to detect a change in audio quality with the movement. I checked the polar pattern around the microphone, and found that it had quite good rejection to the sides and rear. As a directional mic, the from d:screet SC4098 exhibits proximity effect, where the bass response increases when speaking closer to it; I only really noticed this effect from an inch or so away—closer than the mic would normally be used in practice.
Checking the microphone for its sensitivity to plosives such a P-pops, I spoke directly on-axis using consonant sounds that expel a burst of air, such as “Puh,” “Buh,” and “Duh.” At typical working distances, the d:screet SC4098 is fairly resistant to these sounds, and even at two inches away the mic didn’t “pop” unless I deliberately sent out an exaggerated burst of air with the “P” consonant. Other consonants and vowels were reproduced clearly, with no distortion or extraneous noises. Even with the windscreen, the microphone was sensitive to wind or breath blown directly into it, so if used in a breezy outdoor setting it should be shielded from the wind for best results.
Since I am familiar with DPA’s instrument microphones, I decided to try it with an acoustic guitar as a secondary use. I placed the connector barrel of the gooseneck into a smaller mic clip, put it on a boom stand, and used the flexibility to position the mic toward the guitar while I was seated. The response was excellent, capturing the range of the instrument’s sound as a good condenser should. So keep in mind that the d:screet SC4098 can easily fill in when you need to mic an acoustic instrument, combining great frequency response and isolation.
To the Sanctuary
With the help of Randy Partch, sound engineer at Sierra Presbyterian Church in Grass Valley, Calif., I tried the d:screet SC4098 in the sanctuary. The pulpit is located on an extension out toward the congregation, which happens to be directly under the loudspeaker cluster—a position that has been perennially prone to feedback. Their current solution for the pastor is a DPA headset.
We positioned the d:screet SC4098 podium mic on the pulpit, and angled it toward the presenter’s mouth. In this position, the polar patterns of the microphone and the loudspeaker were intersecting to some extent. At a flat EQ setting, pushing the fader to a level sufficient to bring the voice to the back of the room, the system was on the edge of feedback. With about 6 dB of attenuation at 250 Hz, and 3 dB at 3KHz and 12KHz (shelving), we were able to raise the level to usable levels, though the system was still on the edge of feedback. Tilting the mic element downward a bit, additional level was possible. As mentioned above, this particular placement has always been a trouble area.
Moving back a few feet behind the cluster, the mic provided more than sufficient level at a distance of eight inches or so away, and sounded excellent with no ringing. Partch comments that “the mic is really crisp but not at all harsh” on the high end, adding that it was one of the most natural sounding mics he had heard in the space.
Podium Mic Variants
DPA offers a variety of options with the d:screet SC4098. Three lengths of goosenecks are available, at 15, 30, and 45 cm (6, 12 and 18 inches). The goosenecks can be flexible along their entire length, or just at the top and bottom as in the test model. The mic can end in either an XLR connector, or their MicroDot connector for connection to a wireless transmitter. With the latter solution, a wire-free podium can be placed anywhere, with the signal transmitted to a remote receiver. Custom variants with a 120-cm / 48-inch boom are also available, as well as a hanging mic version.
A good podium microphone should be readily adjustable to pick up the presenter’s voice, allow sufficient gain before feedback, reproduce the voice naturally and with intelligibility, permit some degree of movement without a great change in level or tonal quality, and be relatively resistant to P-pops and other induced noises. The DPA d:screet SC4098 is that and more—with a great-sounding mic element on a solidly built, versatile gooseneck. The 4098 is great for spoken word, singing, and can even double as an acoustic instrument mic.