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SVS Prime Tower and Center Loudspeaker Measurements and Analysis

By Tarunvir Bains

The measurements were taken as per the Audioholics Loudspeaker Measurements Standard.

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SVS Prime Tower On-Axis Frequency Response

Sensitivity of the Prime Towers sits just around 87dB/2.83v at 1 meter which is exactly how SVS rated them. on-axis frequency response at 1 meter from the speaker shows roughly a +/-3db variation and exceptional extension all the way down to around 30Hz - which given the enclosure-size, driver-size, sensitivity, and price-point is quite an accomplishment. Overall the response appears linear, but with a slight peaking in the treble from 4kHz to 8kHz which may partly explain the occasional mild sibilance that I heard with certain program material.

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SVS Prime Center On-Axis Frequency Response

The Prime Center’s sensitivity isn’t actually much lower than the tower, at about 1dB less, and the frequency response is free of the treble spike found in the tower. I think that with its extension, this speaker could probably get away with some port plugs for blending to a subwoofer where placement might be an issue.

Next, the listening window response was measured. This evaluates the frequency response at +/- 30 degrees horizontally off axis, +/- 15 degrees off-axis horizontally and vertically, as well as the on-axis frequency response.

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SVS Prime Tower Listening Window Frequency Response

For a stereo speaker, rarely is the listener sitting directly on-axis. The listening window response shows the general response in the forward direction at angles correlating to typical seating positions. The top curve is an average of the seven angles and shows a mostly flat spectral response, with a somewhat forward emphasis overall. The horizontal response is symmetrical, as the loudspeaker layout is symmetrical. The crossover-induced response dip seen in the 15-degrees below-axis measurement is not only in the Tower, but the center as well – so if you need to place your center above the television, make sure to flip it upside down and tilt it towards the listening area.

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SVS Prime Tower Polar Frequency Response

The polar contour map is an examination of off-axis frequency response at various angles 7.5 degrees apart. Since most rooms provide reverberant sound, it is preferable for late-arriving reflections to resemble the direct response. The Prime Tower shows good off-axis linearity, however the slightly elevated tweeter voicing is evident as the large red zone.

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SVS Prime Tower Polar – Effect of Grille

In its spec sheet, SVSound suggests the grille being acoustically transparent and FEA-optimized to minimize diffraction. My observation based on this contour map is that the grille does appear to successfully reduce excess treble energy to an extent, but its frame does introduce diffraction effects. That’s not a knock on the grille design though; it’s just physics.  You can’t ever have a 100% transparent grille - or as Scotty would put it, “you can’t change the laws of physics”.

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SVS Prime Tower Impedance vs Frequency

The spec sheet claims a nominal 8-ohm load - but the impedance of the Prime Tower does drop to about 4 ohms over portions of the bandwidth (100Hz to 250Hz).  As such, this speaker should be mated to a high quality AVR that is stable in 4 ohms or a separate power amplifier to perform its best. My XLS2000 did not appear to show any strain driving the Prime Towers, for what it’s worth. The saddle in the bass shows the port tuning-point to be roughly 36Hz

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SVS Prime Center Impedance vs Frequency

The Prime Center is an easier load than the tower, but it does have ~3-ohm impedance dip just below 1kHz, but that shouldn’t give a high quality AVR any problems.   My receiver did not appear to strain driving the load at reasonably loud SPLs, which may be helped by the fact that the electrical phase angles are benign. The bass saddle indicates a tuning frequency of approximately 46Hz.

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SVS Prime Tower Harmonic Distortion @ 90db @ 2m

Harmonic distortion components are well under control with the correct ordering of predominantly lower order components and progressively less higher-order. It’s clear the aluminum shorting rings in the woofers are doing their job throughout the range, and the crossover is well-implemented for superior power handling. This relates well to the speaker’s ability to render a clean and resolving reproduction during dynamic passages.

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SVS Prime Tower Cumulative Spectral Decay

CSD, or Cumulative Spectral Decay, is a three-dimensional plot derived from the loudspeaker’s impulse response which can highlight issues. The towers exhibit an almost picture-perfect “waterfall” graph free of any ringing or other anomalies. This indicates quality driver design and selection, solid cabinet construction, and smart crossover design.

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SVS Prime Towers Group Delay

Group delay is the rate of change of the slope of phase. As a rule of thumb, values below 1.6ms in the mid-to-high frequencies will likely not affect sound quality perception. Increasing group delay in the low frequencies is not as objectionable as it is in the mid to high frequency ranges.

 

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