John Bowers Active 1 Speaker System Review

As its name indicates, the John Bowers Active 1 speaker is an “active” system; that is, it has built-in power amplifiers and requires only a line-level audio input for its operation. It is the initial product from John Bowers, Ltd., a company whose founder is the “B” of the well-known British manufacturer, B&W Loudspeakers.

An active speaker (sometimes also called a “powered” speaker) enjoys a number of recognized advantages over a conventional passive speaker, which requires a signal from a power amplifier. The complex and costly crossover network required for a standard multiple-driver speaker system is replaced in an active system by efficient low-level crossover circuits at the input to the amplifiers, rather than at their outputs. The reference to amplifiers (plural) is another key to the properties of an active speaker design. Normally at least two power amplifiers are used, one to drive the woofer and the other for the tweeter. In a three-way active speaker, it is not uncommon to use a passive crossover between the midrange and high-frequency drivers, although a third amplifier is another option open to the designer.

Each amplifier in an active speaker system can be matched, in its power capabilities and frequency response, to its associated driver, thus greatly reducing or eliminating any undesirable interaction between an amplifier and the complex impedance of its driver. Amplifier intermodulation distortion, though rarely a problem in any case, is also effectively eliminated by channeling different frequency ranges to separate amplifiers. Bass response, for any given enclosure size, can be extended by active equalization in the low-frequency amplifier. An integrated protection system can prevent damage to either the amplifiers or the drivers from excessive inputs. Integrated tone controls can be designed to compensate for variable room acoustics. Finally, the complete package (speaker and amplifiers) is inherently compatible and easy to operate.

While all these advantages might suggest that active speakers are “the way to go,” they have disadvantages as well. Active speakers are usually expensive, though not unreasonably so compared with the cost of purchasing separate amplifiers and speakers. To the hard-core audiophile, active systems have the disadvantage of removing freedom of choice in component selection. There is also a more tangible disadvantage: the complete loss of use of the system should either the drivers or the amplifiers fail, since user replacement is not possible.

The John Bowers Active 1 can be considered either a two-way or a three-way system, with two apparently identical 6-inch Bextrene-cone woofers operating in a ported enclosure. The output of one, the bass driver, is rolled off above 300 Hz by a passive equalizer while the other, the bass/midrange driver, continues up to about 2,000 Hz before its electronic crossover to the single 1-inch polyamide-dome tweeter.

Both woofers have the same low-frequency response and are driven by an amplifier rated for 200 watts into 4 ohms. The tweeter is driven by a 100-watt (8-ohm) amplifier. The electronic components are entirely enclosed within the speaker cabinet, whose back is a metal plate with external heat-sink fins. There are two rotary-switch frequency-trimming controls on the rear of the cabinet. The three-position HF switch provides the option of a small boost or cut in response above 3,000 Hz. The six-position LF switch boosts or cuts the response below 200 Hz to compensate for the effects of room boundaries on the loudspeaker’s bass response.

Other rear-panel features include a power switch and a.c. line-cord connector, a phono-input jack for unbalanced inputs, and a socket for balanced audio inputs (a slight internal wiring change is required for this mode). There are also red and green pilot lamps. The red light indicates that the system is powered. Any audio signal appearing at its input connectors automatically switches on the amplifiers (together with the green pilot lamp). The system remains active for about 15 minutes after all input has been removed, then it shuts itself off. In operation, the power consumption of each Active 1 ranges from 120 watts at zero drive to 400 watts at full drive. In standby mode it draws only 4 watts of power.

The specifications of the Active 1 include a frequency response of 45 to 18,000 Hz ±2 dB with the lf control set to maximum, a 30,000-ohm input impedance (balanced or unbalanced), and a dispersion of more than 60 degrees horizontally and 10 degrees vertically. The input sensitivity is rated at 175 millivolts (mV) for a sound-pressure level (SPL) at 1,000 Hz of 95 dB measured at 1 meter.

The John Bowers Active 1 measures 24-5/8 inches high, 10 inches wide, and 15-3/4 inches deep including its cloth grille, and it is supplied with a stand that places its top 33-7/8 inches from the floor. Each system unit weighs 66 pounds. The cabinets are finished in black-ash, natural-oak, or walnut veneers. Price: $2,995 per pair.

Lab Tests

Our measurements followed conventional practice except that no external amplifier was used and neither the voltage across the speaker drivers nor their actual operating power levels were measurable (or of any importance). The Active 1’s sensitivity for our reference 1,000-Hz acoustic output of 90-dB SPL at 1 meter was 135 millivolts. Our low-frequency distortion measurements were made at the same input level. We measured the response first with the speaker’s controls set as received—HF at the middle, or 0 setting, and lf just below its middle setting—and made additional measurements to determine the effects of the controls at their limit settings. Although we made close-miked measurements at each of the woofers to establish their operating-frequency limits, we also measured their combined overall response with the microphone midway between them and close to the front of the cabinet.

The room response of the Active 1 speakers was very smooth, sloping gently down as frequency increased. The woofer response was comparably flat and smooth, and the two curves spliced easily to form a composite curve that dropped a total of about 8 dB from 100 to 20,000 Hz, with no irregularities greater than 2 dB in that range. The woofer output decreased rapidly below 80 Hz, reaching the 20,000-Hz level at 55 Hz. We were unable to measure the output at the woofer port, which was inaccessible underneath the enclosure and surrounded by the perforated-steel support structure. Its small size relative to the area of the two woofers suggests, however, that its contribution to the total bass output would be relatively slight.

The HF control varied the output by 2 dB in the 13,000- to 20,000-Hz range, with a decreasing effect down to about 4,000 Hz. At maximum boost the control flattened out the response curve slightly. The lf response adjustment range was considerably greater, about ± 5 dB below 150 Hz and less than 1 dB at 700 Hz. The factory setting gave the flattest overall response in our composite curve as well as the best sound with the speakers 2 to 3 feet from the wall behind them.

The bass distortion was extraordinarily low, less than 1 percent from 100 down to 40 Hz and only 3.5 percent at 30 Hz. Encouraged by the smoothness of the speaker’s midrange response, we also extended our distortion measurements to higher frequencies, where it increased gradually from 0.1 percent at 200 Hz to 0.24 percent at 600 Hz. These measurements were made with a 135-mV input, corresponding to a comfortably loud 90-dB midrange output level. The amplifiers could be turned on by an input of less than 1.5 mV and remained on for at least the rated 15 minutes after the signals were removed.

For our pulse-power tests we measured the peak-to-peak sine-wave input (1 or 2 cycles on, followed by 64 to 128 cycles off) and observed the speaker’s acoustic-output waveform as the input level was increased. At each of our test frequencies (100, 1,000, and 10,000 Hz) the output saturated at an input of 8 volts peak to peak, or 2.83 volts rms. There was no evidence of clipping distortion, and we heard no raspy sounds from a woofer cone’s reaching the end of its linear travel. The only sign that a limit had been reached was that the acoustic output no longer increased with larger input signals. These tests confirmed the effectiveness of the Active 1’s protection system.

The maximum input signal corresponded roughly to an acoustic output of 116 dB at all test frequencies. To relate this to similar measurements we make on conventional speakers, consider a system with a sensitivity of 90 dB SPL with 2.83 volts (“1 watt”) input, which is above-average sensitivity for today’s hi-fi speakers. An output of 116 dB would require an input power of 400 watts, making such a system the rough equivalent—in this respect only—of the John Bowers Active 1. Less sensitive speakers might have to be driven with more than 1,000 watts to produce the same sound level as the Active 1.

Quasi-anechoic measurements made with the IQS FFT analysis system confirmed the smoothness and other sonic properties of the Active 1 system. Axial response curves made at distances of 1 and 2 meters from the speaker revealed a small (3-dB) peak at 7,000 Hz, but it did not appear in measurements made 45 degrees off axis. The FFT measurements showed a response variation of ±2 dB from 300 to 23.000 Hz on axis, and at 45 degrees off axis the response dropped off above 10,000 Hz. The phase linearity of the speaker was very good. Its overall group-delay variation was 0.2 millisecond from 23,000 to 5.000 Hz and reached a maximum of 0.4 millisecond at 300 Hz. According to the manufacturer, the system contains electronic delay compensation to correct for differences in group delay between the bass and treble drivers; it appears to be very effective.

Comments

The John Bowers Active 1 certainly measured like a fine speaker, and we are happy to report that it sounds as good as its measurements imply—beautifully balanced and uncolored. We found it equally enjoyable with the HF control at 0 and at maximum boost. The bass output from the two 6-inch drivers may not satisfy those who are accustomed to using subwoofers, but it compares very well with the output from good 12-inch woofers in cabinets at least twice the size of the Active 1. If you like a lot of bass, setting the LF control to maximum will help, although we often found the resulting sound a bit too heavy. The important thing is that this system has enough response flexibility to adapt to a wide variety of listening environments and tastes. Very few speakers we have used are as well equipped in this respect.

The Active 1 looks deceptively small from the front (it is considerably deeper than it is wide), but it is a heavyweight. It is supplied with plastic glides that distribute its weight sufficiently to prevent indenting floors or carpets. It is also furnished with sharp feet (“carpet spikes”) for those who prefer their speakers anchored to bedrock, or as nearly so as possible.

We compared the John Bowers Active 1 with some other more conventional (unpowered) speakers, including a few in its own price range. Its sound was definitely in the same class as the best of them, although of course tastes differ so widely that it would be foolhardy to make any firm comparisons. And when you consider that a good power amplifier for speakers of this caliber is likely to cost $500 to $1,000 and would still not be able to provide the same degree of protection (and probably not the same maximum undistorted sound level) as the Active 1 system does, even its price begins to look more down to earth.

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