It should come as no surprise that Carvin, like other manufacturers that have a wide range of products, has a line of low-cost microphones. What sets Carvin apart, however, is that it sells directly to the consumer; without a middleman, the company can offer its products at even lower prices than you would expect. As a result, Carvin is able to sell the Chinese-made CTM100 — a large-diaphragm, multipattern tube mic — for less than $300. The CTM100 is remarkably versatile, and its Class-A circuitry, ability to handle sound-pressure levels up to 125 dB, and nine polar patterns make it a multipurpose workhorse (see Fig. 1).
FIG. 1: With nine polar patterns to choose from, the Carvin CTM100 can be used in a variety of recording situations.
The CTM100 has a gold-sputtered 1-inch diaphragm that is 5 microns thick. The mic has a 12AX7 tube in its body, which is about as trim as it can be after accommodating the tube. The CTM100 comes with a power supply that has a 9-position polar-pattern switch, a 30-foot 7-pin mic cable, a spider-type elastic shockmount, a foam windscreen, and a molded ABS-plastic travel case.
The shockmount is handy and works well if left alone. I noticed, however, that when I handled and repositioned the mic, the elastic band tended to disconnect from its mounting. In addition, the metal arms that hold the elastic are pointed toward the mic, and their edges could scratch the CTM100's surface if not handled carefully. On one of the two review units, a piece of the shockmount swivel nut was missing.
I tested the mic on male and female vocals, acoustic and electric guitar, acoustic bass, and percussion. In an attempt to replicate what a user might do with a one-mic/one-preamp setup, I recorded several acoustic instruments, one by one, to build up a song over several passes, using a solid-state Drawmer 1969 preamp to better discern the mic's frequency response.
In a side-by-side comparison on vocals with a couple of other large-diaphragm, multipattern tube mics — a Neumann UM57 and an SE Electronics Z5600A — the CTM100 was in the middle in terms of output level. Its gain range is welcome, because the hotter output of the Z5600A quickly overloads my mic preamps when recording high-volume sources.
On most of the vocal comparisons, the response of the CTM100 in the cardioid setting was very good. It wasn't always my favorite choice once it was blended into a mix, but it was always usable. Overall, the mic is a bit on the bright side, but without harshness. It produces very little self-noise and has a clear and pleasing response on male and female vocals.
Although vocal recording may be the primary application of this mic for most users, the real strength of the CTM100 is in its sound-sculpting abilities, thanks to its multiple polar patterns. The mic's versatility was especially useful when recording a drum kit. To be able to check for consistency, I had two of the mics for the review. I used one as an overhead mic 7 feet above the kit, and the other as a distance mic, about 15 feet away from the drums and 5½ feet from the floor. The high-mid boost of the mic enhanced the crack of the snare drum and the zing of the cymbals in the overhead position. If you prefer a less direct sound, using it as a room mic would give you a more cohesive sound of a full kit. The multipattern aspect of the mic lets you dial in the desired boom, with the omni position providing the most lows.
I recorded the drum tracks with the mics set to cardioid, omni, and figure-8. The omni pattern has significantly more bass response than does the cardioid pattern. When I set the overhead CTM100 to bidirectional, the upper half of the frequency range had a noticeably different quality than did the cardioid setting. It was a nice surprise to hear that much tonal variety in a microphone in this price range.
To hear how a number of tracks that had been recorded with the CTM100 blend together in a mix, I overdubbed several acoustic instruments on top of the drums. As you would expect, choosing the right mic placement and polar pattern are the keys to success. The CTM100 in cardioid mode gave a somewhat bright and prickly response on acoustic bass and guitar, and I had to work to find the best positions for the mic and performer. I usually use two or three mics for an acoustic-guitar overdub, and in that context, the CTM100 would be handy as either a close or distance mic, largely due to the number of pickup patterns.
Piano was next on the list, and it was easy to get a nice sound. The CTM100 in the cardioid setting produced a pleasantly hazy, perfect background sound when placed about seven feet from the open top of an upright, and about six feet above and pointing down at middle C. The highs were rolled off substantially, but there was still a tiny bit of the zing coming off the strings. For more definition and high-frequency response, it was simply a matter of bringing the mic closer.
Jack of all Trades
Inexpensive condenser mics often have an unnatural (or at least a more noticeable) upper-mid boost compared with top-shelf mics of a similar design. Consequently, you tend to notice the less desirable elements of a mic as the tracks pile up. As I added acoustic instruments to my song, the CTM100 began to reveal its overpronounced upper midrange.
If I were to go back and carefully optimize mic placement and polar pattern on every instrument, I could probably build a mix that sounded a bit more natural. As it was, I applied gentle boosts and dips of equalization where needed, and with a little compression and expansion, I was able to get quite usable and musical results.
The CTM100's components aren't audiophile quality, but the mic sounds good with voices and on a variety of instruments. To make this mic do what you want may take some work, and you might end up fiddling with the recorded sound more than if you had a cabinet full of high-end, single-purpose mics. If, however, you're looking for a quality multipattern tube mic for less than $300, you should check out the CTM100.
Rich Wells oversees the Supreme Reality, a recording studio and a band in Portland, Oregon.
CTM100 SPECIFICATIONS Capsule Type condenser, center mount Frequency Response 20 Hz — 20 kHz Polar Patterns cardioid, hypercardioid, omni, figure-8 Dynamic Range 133 dB Maximum SPL 125 dB Low-Frequency Rolloff no Attenuation Pad no Operating Voltage 48V Dimensions 9.75" (L) × 2.75" (W) Weight 1.8 lbs.
OVERALL RATING [1 THROUGH 5]: 3.5
PROS: Pronounced difference in response among various polar patterns provides versatility. Low price.
CONS: Can overemphasize high mids in an unpleasing way. Shockmount elastic comes undone easily.