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Audio Technica 30 Series

AT3525 / AT3527 / AT3528 Microphones By Paul White
Published May 1998

Left-to-right: AT3527, AT3528 and AT3525 microphones.Left-to-right: AT3527, AT3528 and AT3525 microphones.

Paul White gets an earful of a new range of quality mics that goes easy on the pocket but doesn't compromise on sound.

Like any company that keeps an eye on the studio equipment market, Audio Technica are conscious that there's been a heavy downward pressure on the price of microphones over the past couple of years, and that their once bargain‑priced AT4033 is proving harder to sell to private studio owners when models such as the AKG C3000 and the Rode NT1 can be picked up for less than £250. I would imagine that dropping the price of the 4033 to this level would be out of the question, as it's really a very good mic that can't be cheap to build, so instead the company has launched a new range — the 30 Series.

AT3525 Cardioid

So far, the 30 Series comprises just three models: the AT3525, the AT3527 and the AT3528. The first of these is very distinctive and combines a more or less conventional‑looking side‑entry basket with an exceptionally short body, resulting in a stubby, almost military appearance. Overall, the standard of engineering is all that we've come to expect from Audio Technica — stylish and mechanically rugged.

The AT3525 is a medium/large‑diaphragm, back‑electret microphone with a fixed‑cardioid polar pattern, switchable 10dB pad and switchable 80Hz, 12dB/octave high‑pass filter. Both switches are recessed and located on the underside of the mic rather than on the side, as would be more usual. The capsule employs a very thin diaphragm with a gold surface layer, suspended above a precision‑milled backplate, and artificial ageing is used to stabilise the capsule performance. The output from the mic is on a conventionally wired balanced XLR with gold‑plated pins, and a sturdy shock‑mount is included, along with a soft, zip‑up case. Full 48V phantom power is required (+/‑ 4 V).

One of the AT3525's claims to fame is that it can handle very high SPLs, up to 156dB with the pad switched in (1% distortion at this level), so it can be used in virtually any environment, including in close proximity to drums and other loud percussion. Predictably, this reduces its sensitivity slightly when compared to other typical large‑diaphragm mics (‑48dB (3.9mV) ref 1V at 1 Pa), but it's still sensitive enough for most typical studio instrument and vocal recording applications. The useful frequency response extends from 30Hz to 20kHz, and the included plot shows a nominally flat response up to 2kHz, followed by a wide presence rise, maxing out at around 4dB before dropping off again at around 12kHz.

AT3527 Omni

The AT3527 is a very conventional looking 'stick' microphone with a fixed omnidirectional polar pattern. Like the other mics in this series, its capsule works on the back‑electret principle, and as with the previous model, the AT3527 can handle very high SPLs, up to 158dB SPL with the pad switched in. Both pad and 80Hz high‑pass filters are provided, accessed by means of small slide switches recessed into the side of the microphone body. These must be activated using a small screwdriver or toothpick, so there's no chance they'll accidentally get moved. Finished in the same matte‑grey spattered finish as the other models, the body appears to be turned from a single piece of metal, and there's no obvious way to gain access to the capsule, other than removing the XLR output connector and working your way in from that end.

The AT3527 turned in a lovely acoustic guitar sound and a surprisingly warm, well‑rounded vocal sound.

Again, the frequency response is nominally flat with a deliberate presence peak, but in this case the presence lift doesn't come in until 5kHz, with a maximum at around 8kHz. The sensitivity is just slightly less than for the AT3525, with a similar overall frequency response. The off‑axis response starts to come in a little at high frequencies, resulting in a drop of up to 1.5dB at 8kHz, 180 degrees off‑axis, but this is not untypical for a microphone of this geometry, and is of no real concern in standard studio applications.

AT3528 Cardioid

The AT3528 looks physically similar to the AT3527, except that the slotted vents below the end grille give away the fact that it's a cardioid rather than an omni model. The overall dimensions are similar (the AT3528 is actually 3mm longer than its omni sibling), and both pad and LF roll‑off switches are fitted in the same place. Studying the polar pattern graph provided shows the off‑axis response to be exceptionally good up to between 90 and 120 degrees off‑axis, after which the low‑frequency response starts to become more omnidirectional and the very high end tends to drop in level slightly. Again, this is a typical characteristic of all microphones built around this type of geometry and is not generally a problem. Though the overall frequency response is similar to the other models in the range, the presence peak is slightly different, with a gentle rise starting below 2kHz and peaking at around 10kHz before rolling away.

In Use

The AT3525 was up for test first and was directly compared with the AT4033 and a Rode NT1, where its lower sensitivity was immediately apparent. Adjusting the mixer gain to even out the levels brought no obvious noise penalties for close‑miked vocals, guitar or sundry ethnic percussion and the mic came over with a clean, presency sound that at the same time wasn't over‑bright. For me, the mic sounded at its best when the source was brought close enough to allow the proximity effect to start taking effect, and on vocals this creates a rich, quite warm sound with plenty of presence and detail.Tonally, the AT3535 isn't exactly like any other mic in the AT range, but it still has that quality family sound. It also seems to have a very good transient response, which allows it to work well with percussive or picked sounds. It's worth noting that the off‑axis rejection is exceptionally good, which can be helpful in situations where spill is a potential problem.

Taking the mics slightly out of order, I tried the AT3528 next, as this also has a cardioid pickup pattern, and it actually sounded quite similar to the 3525. Checking back with the frequency response plots showed the presence peaks fell in roughly the same place, so perhaps this isn't surprising. Again, the proximity effect warms up the sound very noticeably as you work closer to the mic, and overall the quality of reproduction was clean and even.

Perhaps the biggest surprise of the bunch was the AT3527 omni mic, because, in direct comparison with any of the cardioid models I tried, it sounded instantly more natural and less constricted. When tried on the acoustic guitar, it managed to gloss over the slightly 'scratchy' quality that all the cardioids used in the test had homed in on. Tried side by side, all the cardioids sounded fine, but one listen to the omni shows that there is a timbral price to pay for the directional tightness of a cardioid mic. It's almost as though all cardioid mics have a slight nasal quality, which evaporates when you switch to a nice omni model. The AT3527 turned in a lovely acoustic guitar sound and a surprisingly warm, well‑rounded vocal sound. Being an omni, it doesn't have a proximity effect, so the sound doesn't seem to thin out as you move further away, though a pop shield is a good idea, as omnis can pop quite badly if you blow a blast of air in their direction. Interestingly, trying to create deliberate popping while speaking was actually quite difficult, but breathing close to the mic did cause audible pops.


These are all very pleasing microphones that can be used in nearly all studio recording situations, even very close to drums. The AT3525 acquits itself well as a solid‑sounding vocal mic, it delivers a bright, clean acoustic guitar sound, and it works well with virtually any kind of percussion too. It would also make a good drum overhead, as, indeed, would either of the other two mics in the series.

For general‑purpose cardioid work, the 3528 takes everything in its stride, from acoustic guitar and vocals to drums. If you prefer the capacitor sound for snare‑drum miking, this model will take the level, and it's also small enough to allow precise positioning without it proving too much of a target from the drummer.

As mentioned earlier, the AT3527 surprised me with its smooth, confident sound and it does for the ears what well‑worn‑in, favourite shoes do for the feet. If you have a problem with sounds coming over as being too harsh but you don't want to lose any HF detail, give the AT3527 a try. All three mics perform their jobs well and the aggressive pricing of this new range means that you can't afford not to consider these models when you're in the market for a new mic or two.

Loud's Allowed

All three microphones are designed for general‑purpose use, though their specifications provide some clues as to what they might do best and what they might do less well. One of the main features of this range is its ability to withstand very high SPLs, (Sound Pressure Levels) but an inevitable trade‑off is some loss of sensitivity. On the one hand, you know you'll never have to worry about the mic cracking up from being too close to a drum kit, looking down the bell of a brass instrument or being placed close to a super‑loud rock vocalist, but the other side of this coin is that none of these mics would be the best choice for miking unduly quiet or long‑distance sounds. Having said that, they're quite sensitive enough for most typical studio jobs, including miking acoustic guitars and so on.


  • Well engineered, both mechanically and electronically.
  • Good performance at an attractive price.
  • Pad and filter switches fitted to all models.
  • Can withstand very high SPLs.


  • Reduced sensitivity makes them less suitable for quiet and/or distant sound sources.


These microphones represent good value and are genuinely versatile. The omnidirectional 3527 was my surprise favourite of the bunch, but they all perform well within their price range.


AT3525 £295.95; AT3528 and AT3527 £174.95 each. Prices include VAT.