As I mentioned in my recent review of the Audio Technica 4060 microphone, Audio-Technica has emerged over the past decade as a serious manufacturer of high-quality studio microphones, with a market niche that might be described as “good mics for not a whole lot of money.” My experience with AT mics over the years has been highly satisfactory.

The Series 30 electret condenser microphones are smack in the middle of that niche, and include three models for your consideration: the 3525, a side-address cardioid microphone, and two small “pencil” mics, the 3527 (omnidirectional) and 3528 (cardioid). MSRP for the 3525 is $399, while the 3527 and 3528 each go for $299.

All three mics have both 10 dB attenuation switches and an 80 Hz. roll-off switch included. A shock mount is included with the 3525, and foam pop filters are included with the 3527 and 3528. All three mics require 48 Volt DC phantom power.

Audio Technica specifies the sensitivity of the 3525 as 3.9 mV (-48 dBV) output and the sensitivity of the 3527 and 3528 as 2.8 mV (-51 dBV) output, for a 94 dB SPL acoustic signal at the microphone. Noise is specified as equivalent to 22 dBA SPL for the 3525 and 24 dBA SPL for the other two mics. Maximum level approaches 150 dB SPL without attenuation for all three mics. Very respectable figures, all. Easy to work with.

So How Do They Measure?

I conducted an array of objective tests with the three mics, using my TEF analyzer and B&K 4007 measurement microphone as a reference. I measured on-axis frequency response, as well as response @ 30°, 60°, 90° and 180° for the cardioid mics. I also recorded pink noise and a variety of instrumental and vocal signals on all three mics (and the B&K) simultaneously, so that I had a multitrack recording for comparison listening purposes. An objective analysis of the pink noise over time as perceived by the various microphones proved to be quite useful and revealing.

The most general comment is that the three mics have a strong family resemblance that manifests itself as a 9-10 kHz. peak in the on-axis response tests. Further, my measurements tended to confirm Audio Technica’s specs, so I’m inclined to believe them. However, the three mics have somewhat different responses below 8 kHz., and those different responses have a significant bearing on how the mics sound.

The 3525

The 3525 is the generally best performing mic of the three, with its somewhat elevated sensitivity and reduced noise floor. There is a broad 2-3 dB peak between 4 and 10 kHz. and a gentle 5 dB roll-off below 200 Hz., as compared to the B&K omni (a function of good directionality, among other things). These characteristics were confirmed with the pink noise measurements and were easily audible. Off-axis response was quite good to 90°, while the level at 90° was down about 6 dB. At 180° response was widely variable and generally down 15-30 dB. There was a constant directivity peak at about 10 kHz. that holds up through 90°.

The 3527

The 3527 omnidirectional mic has a very flat response, with a 2 dB peak around 8-10 kHz. This was confirmed with pink noise measurements, which were so close to the reference (when corrected for level) that the power response could be considered as identical to the B&K except for the slight peak.

The 3528

The 3528 cardioid mic has a high frequency response peak that is identical to the response of the 3525 (corrected for level). However, below 2 kHz. the response fell off gradually, so that it was down 2 dB at 1 kHz., 4 dB at 500 Hz. and 6 dB down at 200, where it leveled off, relative to the 3525. This response behavior was also clearly seen with the pink noise.

All in all, these are very respectable frequency response curves and microphone behaviors. No evidence of design struggles or serious compromises to obtain performance. On paper, the mics look VERY decent.