Introduction

At CES, 2003, I saw lots and lots of stuff, some of it new, some of it not so new. Adire Audio has been around for awhile, but in the past, they manufactured drivers rather than speakers.

When I went by their room at The Alexis Park Hotel, where many of the high-performance audio companies tend to aggregate, I was surprised to see that Adire had begun to make the complete product, namely bookshelf speakers and subwoofers.

I was even more surprised when I heard the Kosalas, reviewed here. They were being driven by a set of low powered tube amplifiers, and the sound was spectacular. The reason the tube amps worked so well, is that the Kosalas are very sensitive (95 dB). This means that a low powered amplifier, say 25 watts, will be fine with these speakers.

The Design

The Kosalas are ported, and tuned to 56 Hz. If you look at the photograph, you might ask, "Where is the tweeter?". Indeed, when I first saw this speaker, I thought it might be a subwoofer. However, the tweeter is a compression design, mounted at the rear of the 10" bass driver, with its opening aimed down the center of the woofer. The dust cap that you see in the photo is transparent, allowing the high frequencies to pass through. This is important because it produces the sound from one spot, unlike most speaker designs that have a woofer in one place on the front, and a tweeter in a different place.

Two pairs of gold-plated speaker binding posts, with metal straps, provide for bi-wiring or bi-amping. The speakers are finished with real oak, either honey colored, or black. The front and rear are not veneered, so this means you would listen to them with the grille on, as the black paint is not particularly appealing.

The Sound

I tested the Kosalas with a Sony SACD Player, Balanced Audio Technology VK-5i Preamplifier, Balanced Audio Technology VK-75SE Power Amplifier, Nordost Cables, and BetterCables.

What I heard in my own environment confirmed what I had heard at CES. These speakers are really very good, and especially so at this price. The lack of veneering on the front and rear helps to keep the price down, and as long as you are comfortable using speakers with the grille on, they will appear no different than front-veneered speakers with the grille on as well.

I would characterize the Kosalas as very warm and laid back. I think that is what Dan Wiggins, at Adire, had in mind, as evidenced by his demonstrating them with a tube setup.

They also have a huge soundstage, almost twice as wide as the physical placement of the pair from left to right. I asked Dan about this, and he said that the placement of the tweeter directly in line with the center of the woofer, along with the crossover, was the reason.

I like classical music more than other types, and like to listen in the evening with a cup of tea and a newspaper. I don't like the sound to intrude on my reading. That is probably why the Kosalas were so appealing to me, with their laid back attitude.

As to tonality, all orchestral instruments, including the very difficult piano, sounded completely natural. Voices too, had a natural aura about them. No chestiness, nasality, or tizziness was there to destroy the illusion.

On the Bench

At 50 Hz and near 100 dB (I decided not to risk turning it up any louder, as the speaker was straining), the distortion was rather high, at almost 9%. Adire says that the Kosala is optimized for sounds above 50 Hz, and they were not kidding.

At 100 Hz, the performance was much better, with THD at a very manageable 0.34%.

At 1 kHz, distortion had increased to 1.31%. This is near the 2.4 kHz crossover between the woofer and the tweeter, so the 10" woofer was starting to have a tough time with these higher frequencies.

At 5 kHz, which is in the tweeter's range, THD was back down to less than 0.5%. Excellent.

The frequency response results (quasi-anechoic) are shown below. It is not as smooth as some speakers, not as rough as others. It's acceptable for this price range.

Impedance and electrical phase measurement results are shown below. The minimum impedance is 9 Ohms, and the maximum is 28 Ohms. DC resistance is 6.12 Ohms. The phase stays within + 45⁰ to - 45⁰, which is very good.

Conclusions

The Adire Audio Kosalas are a surprisingly good speaker for less than $700/pair, with real wood veneer. The tweeter centered with the woofer produces an excellent soundstage, and their sensitivity, along with an average impedance of about 12 Ohms, would make them a piece of cake for tube amplifiers (tube amps love high impedance speakers), as well as home theater applications with mass market receivers.

- John E. Johnson, Jr. -

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