Spendor S3/5R2 loudspeaker Measurements

Sidebar 3: Measurements

I measured the Spendor S3/5R2 loudspeaker with DRA Labs' MLSSA system, using a calibrated DPA 4006 microphone to measure the speaker's frequency response in the farfield, and an Earthworks QTC-40 mike for the nearfield responses. The S3/5R2 is very similar in size and basic topology to the S3/5se, which Art Dudley reviewed for Stereophile in July 2003. You can find my measurements of the earlier speaker here.

The S3/5R2's voltage sensitivity is specified as 84dB/W/m, but my estimate was just 81.7dB(B)/2.83V/m, which is essentially the same as the 2003 version. However, as with the earlier speaker, the S3/5R2's plot of impedance magnitude and phase (fig.1) reveals it to be a very easy load for the partnering amplifier. The magnitude drops below 8 ohms only in the lower midrange, and stays well above that figure for most of the audioband. The single peak in the bass, reaching 32.6 ohms at 76Hz, indicates that this is the tuning frequency of the sealed box, which is where the low-frequency response will be down by 6dB.


Fig.1 Spendor S3/5R2, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

A small wrinkle at 200Hz in the impedance traces suggests that there is an enclosure resonance of some kind at that frequency. However, investigating the panels' vibrational behavior with a simple plastic-tape accelerometer revealed nothing untoward at that frequency, though there was a strong resonance at 316Hz on the sidewalls (fig.2). I would have expected this to add a slight degree of midrange congestion.


Fig.2 Spendor S3/5R2, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of side panel (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).

Though there is a slight rise in the upper bass in the Spendor's nearfield response (fig.3, below 300Hz), this is mostly due to the nearfield measurement technique. The S3/5R2 doesn't have as much of an upper-bass bump as the classic LS3/5a, or the similar-sized KEF LS50, which I reviewed in December. Higher in frequency in fig.3, the S3/5R2's farfield response, averaged across a 30° horizontal window on the tweeter axis, is even, though with a slight lack of energy in the crossover region. It also looks as if the tweeter is balanced a couple of dB too hot. However, this response was taken without the rather clumsy grille; adding the grille pulled down the output between 3 and 10kHz (not shown) by a dB or so, which is presumably why BJR preferred what he described as a slightly more detailed sound with the grilles removed.


Fig.3 Spendor S3/5R2, anechoic response on HF axis at 50", averaged across 30° horizontal window and corrected for microphone response, with nearfield woofer response plotted below 300Hz.

The S3/5R2's horizontal dispersion (fig.4), normalized to the on-axis response (which therefore appears as a straight line), indicates that the lack of on-axis energy in the crossover region deepens to the speaker's sides. All things being equal, this might make the speaker sound a little laid-back, though it's more likely that it will leave that slightly hot tweeter sounding a little detached. However, it is fair to note that BJR didn't find the Spendor to sound tipped up toward the high frequencies. In the vertical plane (fig.5), a large suckout in the crossover region develops 5° below the tweeter axis, as well as 10° and more above that axis. More than usual, and especially to a greater degree than its predecessor, this speaker will be very fussy about exact listening axis.


Fig.4 Spendor S3/5R2, lateral response family at 50", normalized to response on HF axis, from back to front: differences in response 90–5° off axis, reference response, differences in response 5–90° off axis.


Fig.5 Spendor S3/5R2, vertical response family at 50", normalized to response on HF axis, from back to front: differences in response 45–5° above axis, reference response, differences in response 5–45° below axis.

Whereas the 2003 version of this speaker had the tweeter and woofer connected in the same, positive, acoustic polarity, in the 2012 edition the tweeter is connected in inverted polarity, though the decay of the tweeter's step blends smoothly with the start of the woofer's positive-going step (fig.6). At least on the tweeter axis, this will result in a fairly smooth blend of the drive-units' outputs, though I did note a slight lack of energy in the crossover region. The cumulative spectral-decay plot on the tweeter axis (fig.7) is very clean. (Ignore the black ridge of apparent delayed energy just below 16kHz in this graph; this is due to interference from the test computers' video circuitry.)


Fig.6 Spendor S3/5R2, step response on HF axis at 50" (5ms time window, 30kHz bandwidth).


Fig.7 Spendor S3/5R2, cumulative spectral-decay plot on HF axis at 50" (0.15ms risetime).

The Spendor S3/5R2's measured performance indicates fundamentally good engineering, though it is fair to say that this version is not appreciably better than the 2003 iteration, which measured very well.—John Atkinson

Spendor Audio Systems Ltd.
US distributor: Bluebird Music Limited
500 Witmer Industrial Estates
Niagara Falls, NY 14304
(416) 638-8207

LCDC's picture

I currently own a pair of these fine speakers and have to say that couldnt believe how good they were when i demoed them last year. They blew me away.

Ive got a pretty broad colection of music but these seem to bring a smile to my face whether it's AC/DC, Bjork or Marvin Gaye.

Should i ever buy a new set of speakers, i cant see them being an 'upgrade' in the mid range. Soundstaging is wonderful.

hnipen's picture

In this audio world of today where it's so common to ask for "louder", "bigger", "more bass", "max spl" it's really refreshing to read reviews like this, thx a lot for the nice and very interesting review.

After reading about Spendor S3/5R2 and Harbeth P3ESR also here in Stereophile it's really tempting at least to audition these speakers, there is a distinct beauty in small monitors like this and for some it will be speakers they can live with ever after.

I certainly got a clear wish to get the Spendor's or Harbeth's into the house now :-)

dalethorn's picture

This review describes my experience with the LS3/5a exactly, so this speaker must be something really special.

wgb113's picture

Would have been the KEF LS50.  See how Spendor carried on KEF's BBC tradition vs. KEF's re-imagining of a new one.


walshbouchard's picture

Has anybody demod the new SP2/3R2 I have owned 4 x SP2/3R since 2008 and would be interested to know if anybody out there  has  found  much difference /improvement with the updated R2 over the "R". and if the improvement is really worth the extra cash?


J Walsh

Maidstone UK