Product Review - Acoustic Research AR1 Tower Speakers with Built-In Powered Subwoofer - January, 2000

John E. Johnson, Jr.

Introduction

With the advent of 5.1 channels, five of which have full range digital sound, home theater consumers are faced with lots of problems to deal with. Two of these are that mass market receivers have to share a modest power supply with all the channels, resulting in often-times harsh sound with low-sensitivity speakers that demand all of the power reserves. A second problem is that, with all the speakers taking up so much room, where does one put the subwoofer, or, egads, TWO subwoofers for stereo bass?

Acoustic Research has taken a big step towards solving those two problems with the introduction of the AR1. It has a 95 dB sensitivity, and the subwoofer is built-into the enclosure . . . 15" and 500 watts of power. In fact, there is a powered subwoofer built-into each enclosure, so you can have stereo subwoofers, all in a nice slender cabinet. Of course, this makes each tower speaker very heavy . . . 85 pounds, so I would suggest putting them on a rug rather than using the supplied pointed feet, unless you don't care about dents in your wood floors.

The layout

The main drivers are on the front of the enclosure, with the 1" metal dome tweeter situated in between the two 5 1/4" mid/bass drivers (D'Appolito array). The subwoofer driver is on the side, and the speakers come with one as the left and one as the right, with the subs situated so that the left enclosure has the sub driver on the right, and the right enclosure having the sub driver on the left (in other words, the sub drivers face each other).

The rear panel of the enclosure has one set of speaker binding posts (all metal), an RCA input jack for separate control of the powered subwoofer, and an RCA output jack if you want to connect another powered subwoofer in series. There is also a small rotary control for adjusting the level of the subwoofer at 30 Hz. An LED indicates power on and standby for the subwoofer amplifier. The AC cable is two-pronged (ungrounded) and is detachable.

The sound

The first thing I want to show you is the room response chart. I tested the left speaker, with the subwoofer being driven by the connection through the speaker binding posts (in other words, not using the RCA jack). The response is reasonably flat all the way down to 20 Hz, which is the limit of the tests I use on full range packages. I also used the subwoofer setting of "Ref" on the back of the enclosure. I could get much louder bass when I turned this rotary knob up to higher settings. And, I am sure the sub will go lower than 20 Hz. I could detect no hum or other noise using the speaker connections to drive the subwoofer. Since a typical consumer would buy a pair of these speakers, and since the speaker connection works so well with the subwoofer, I see no reason to use the RCA input because typical receivers only have a mono subwoofer output jack. You might as well have stereo bass, using the left and right channels of the receiver to drive the subs in the left and right AR1 enclosures. Although frequencies below about 50 Hz are non directional, the subwoofers do not roll off until about 100 Hz.

The sound of the AR1s was slightly forward in the midrange area, so it was full bodied. There was no excessive sibilance, and the highs were smooth. Voices were never boomy in my testing. The sound was pinpoint accurate, and center imaging was near perfect. The performance of the subwoofers was phenomenal, thanks to the 500 watts of Class D amplifier supplied by Sunfire. I had not heard a Sunfire subwoofer amp driving a 15" cone before, and WOW! The membranes in my reference electrostatic panels shimmered from the bass intensity. All with no rattling, booming, or clipping. This is some product!

I drove the AR1s with our Balanced Audio Technology VK-500 (250 watts per channel) and the Balanced Audio Technology VK5i preamplifier (both fully balanced). What I noticed immediately was that I only had to turn the volume control up to about 25 instead of the usual 50 on the preamplifier to get a nice loudness level. That's the 95 dB sensitivity raising its head. This is not so important for an amplifier like the BAT VK-500 which has more than 1000 joules of energy storage capacity, but for receivers, it makes an enormous difference. Think of it this way. Let's say you have a receiver with 80 watts per channel and you are using speakers with 89 dB sensitivity. Let's say further that you listen with about 12 watts per channel on average, peaking to 80 watts per channel. Those peaks will severely tax the receiver's amplifiers. With the AR1s, you would only need 3 watts per channel on average, peaking to 20 watts per channel, to achieve the same loudness as with the 89 dB sensitivity speakers.

The implication is obvious. Get sensitive speakers to go with your processor/amplifier or receiver, especially if it is only modestly powered. But, even if you have one of the high-performance receivers (the ones costing $2,500 and having more than 100 watts per channel output), you will benefit from having sensitive speakers like the AR1s. You might not hear the difference at 3 watts, but the peaks will have a much easier time getting through without distortion (notwithstanding the fact that most speakers produce more distortion than amplifiers at high volume levels).

Practically speaking, it would be a little ridiculous to get a set of these speakers to go with a loss-leader $199 receiver, even if the receiver would perform better with these sensitive speakers. The AR1s are top quality speakers, so, obviously, they should be matched with a top quality receiver. In fact, a class A, single-ended triode amplifier drives them to very nice levels, not only because of their sensitivity, but because the built-in subwoofer takes care of a notorious problem with small powered triode amplifiers, namely a weak bass. Acoustic Research actually recommends a 7 watt amplifier in the AR1 specifications. That' something you won't see in a speaker spec sheet very often.

As to using the AR1s all the way around, I would imagine not. In my experience, subs in the rear cause cancellation problems with subs in the front unless you have a phase control adjustment on the subwoofers, which the AR1s do not. So, I would suggest going with one of AR's other speaker models for the rear, but staying with something that is as close to the AR1s without the subwoofer as possible.

Conclusion

Acoustic Research has done us all a huge favor in making a tower speaker that sounds great, plays loud with not much amplifier input, and has terrific powered subwoofers built-in. The AR1 is about as close to "having it all" as you can get.

- J. E. Johnson, Jr. -

� Copyright 2000 Secrets of Home Theater & High Fidelity
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