VR-1 Measurements and Analysis
We spent over four months carefully listening to the VR-1 bookshelf's in a variety of different systems and rooms. They included Reference System 1 , Reference System 2 , and several "bedroom systems." This helped us better understand the performance of these bookshelf speakers in a variety of room acoustics and with a variety of different receivers and amplifiers. We also listened to a host of audio tracks from DVD movies, CD's, SACD's and DVD-Audio formats. And lastly, we measured near field performance of the VR-1's with our Sencore equipment , as well as plotted an electrical phase and impedance curve using LMS. The speaker was placed in the middle of the listening room and measured 1 meter away (near field response). Bass extension was enhanced when the speaker was placed more closely to a corner/side wall. But measuring a speaker at this location is not an accurate way to do a near field response.
In application when mating with the matching subwoofer, our goal was achieve the flattest frequency response from the upper bass to the top end. However, some listeners may prefer closer placement to the walls for more bass reinforcement in applications where no subwoofer is present.
Performance Curves of VR-1
Dark Blue - Impedance Curve: Min impedance is about 4.75 ohms between 150-200 Hz, with a peak of 15 ohms at 70 Hz (around the bass limits of the speaker). Due to the relatively small port and low tuning frequency of around 30 HZ , there is really no usable/audible contribution from the port. Instead, the port acts to limit driver excursion at very low frequencies and increase dynamic range of the speaker. The rising impedance of the speaker starting at around 7kHz exhibits inductive loading.
Light Blue - Electrical Phase Plot: The VR-1 bookshelf speakers have good phase response as indicated by ± 30 degree window it maintains within the entire audio spectrum above 70 Hz. In addition the moderately high sensitivity (89dB SPL @1 watt/meter) and lowest impedance dip of 4.75 ohms indicates pretty much any decent solid state amp should be able to drive these speakers without incident. However, we suspect an amplifier with the lowest possible output impedance would be beneficial due to the reactive nature of the impedance curve to minimize any possible frequency variations.
VR-1 Near Field Frequency Response
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The VR-1 bookshelf's (or Reference Studio Monitors as the Manufacturer classifies them) were placed on 30" stands at least 6 feet away from all walls in a well damped room with carpeted floors and flat ceilings. The on axis response (black) indicated a slight emphasis on high frequencies above 10 kHz. The 30 degree off axis response (cyan) helped to smooth the overall response of the speaker indicating that this speaker may perform better with minimal toe in, especially in lively rooms. |
