BG Z-1 Measurements & Analysis
Impedance & Electrical Phase Response of the BG Z-1
The Z-1's appear to be tuned around 60Hz which makes this speaker ideal to be mated with a quality subwoofer for enhanced bass extension. Phase response was very linear and kept within 0-30 degrees from 100Hz to 20kHz. Impedance is around 7-8 ohms overall with the lowest dips between 5kHz to 20kHz of around 6 ohms. The moderately high efficiency of this design, minimum phase response and almost resistive load profile, (a tribute to the innovative tweeter and good crossover design), makes this a relatively easy load for any decent receiver or moderate power amplifier to drive. More importantly, this speaker should sound more consistent when driven by a variety of amplifiers because of these qualities.
On Axis & 30 Deg Off Axis Frequency Response (300Hz to 20kHz; smoothed) @ 1 watt / meter
Light blue trace is on axis response, dark blue trace is 30 degrees off axis response. The -4dB dip from 2-3kHz as well as the overall dip in response from 2kHz to 7kHz may explain why Arvind found the midrange performance to be somewhat recessed. Based on these measurements, it is advisable to toe these speakers in 15-30 degrees to achieve the most uniform performance.
Spliced woofer/port Nearfield Response with On/Off Axis 1 Meter Response
Useable low end bass extension as confirmed with the impedance measurements and the woofer response above is around 60Hz. It is recommended to apply bass management to these speakers in conjunction with a subwoofer set around 70-80Hz for increased dynamic range and extended bass response.
According to BG, the Z-1 has been designed as a speaker for listening WITH a SUBWOOFER. It was purposefully designed so that when with subwoofer, it delivers full range sound at very low distortion while achieving high SPL levels. They feel the days of small two way monitors that are designed for a small full range stereo system are gone and I personally agree with their sentiments. Mating a sub with a pair of bookshelf monitors such as these, usually provides a better degree of dynamic range, bass extension and overall more articulate mids and top end since the woofer is no longer tasked at producing midrange and low end response.
The Score Card
The scoring below is based on each piece of equipment doing the duty it is designed for. The numbers are weighed heavily with respect to the individual cost of each unit, thus giving a rating roughly equal to:
Performance × Price Factor/Value = Rating
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