Test Bench: Axiom Epic 80/500 Home Theater Speaker System
In the lab
Frequency response (at 2 meters) front left/right 36 Hz to 15.3 kHz ±5.5 dB center 110 Hz to 17.1 kHz ±4.1 dB surround 126 Hz to 17.6 kHz ±5.0 dB subwoofer 28 Hz to 98 Hz ±2.1 dB Sensitivity (SPL at 1 meter with 2.8 volts of pink-noise input) front left/right 90 dB center 90 dB surround 85 dB Impedance (minimum/nominal) front left/right 3.0/9 ohms center 3.9/6 ohms surround 2.9/6 ohms Bass limits (lowest frequency and maximum SPL with limit of 10% distortion at 2 meters in a large room) front left/right 32 Hz at 70 dB center 80 Hz at 87 dB surround 80 Hz at 81 dB subwoofer 20 Hz at 80 dB SPL 104 dB average SPL from 25 to 62 Hz 110 dB maximum SPL at 32 Hz bandwidth uniformity 95%
All of the curves in the frequency-response graph are weighted to reflect how sound arrives at a listener's ears with normal speaker placement. The curve for the left/right front channels reflects response of the M80 with the speaker standing on the floor averaged over a ±30° window. The center-channel curve reflects response of the VP150 averaged over ±45°, with double weight directly on-axis of the primary listener. The surround-channel curve shows the response of the QS8 averaged over ±60°.
Because the M80 will always be used on a floor, all measurements were taken with the speaker on a floor. Both the center and surround channel speakers were measured on a 6-foot stand, which gives anechoic results to approximately 200 Hz. All upper channel measurements are taken at a full 2 meters, which emulates a typical listening distance, allows larger speakers to fully integrate acoustically, and, unlike near-field measurements, fully includes front panel reflections and cabinet diffraction.
The M80 exhibits a 7-dB floor bounce notch at 400 Hz, and the bass to treble balance falls by 1 dB per octave above 200 Hz. The VP150 center channel exhibits significant off-axis lobing that begins as soon as the microphone is moved off center. Our averaging technique tends to obscure it's severity but it's easy to hear the sound change quality at any listening angle as one walks about the speaker. The QS8 surround has clever left, right, upward and downward facing drivers which offer interesting interference patterns at every listening angle to encourage good envelopment for surround sounds.
The EP500 Subwoofer bass limits were measured with it set to maximum bandwidth (Crossover Bypass and Flat trim) and placed in the optimal corner of a 7,500-cubic-foot room. In a smaller room users can expect 2 to 3 Hz deeper extension and up to 3 dB higher sound-pressure level (SPL.)
The subwoofer had excellent dynamics and bandwidth uniformity, delivering 104 dB or greater at any frequency above 25 Hz. It acheived true 20 Hz output within our 10% distortion rating, albeit at 80 dB.
With its crossover set to its Bypass mode, upper bandwidth topped out at 98 Hz. But most other crossover settings (100, 80, 60 and 40 Hz) were as marked on the dial, except for 80 Hz (which crossed over at 64 Hz), and there was no level/crossover control interaction at any crossover setting. The Full trim setting significantly changed the overall response shape ( +8 dB from 25-52 Hz with -20 dB by 100 Hz), while the Half setting simply increased response by 2 dB from 34-53 Hz.