Stereophile – August 2019

stereophile.com n August2019 71

MAGNEPAN LRS

measurements, continued

open for inspection. It was a new kind of fun.

Things got genuinely spooky when I put on the Electric

Recording Company’s new LP reissue of The Country Blues

of John Lee Hooker(Riverside/Electric Recording Company

RLP 12-838). It was a promo copy, loaned by a friend,

and the sound was recording-studio clear in a way I rarely

experience from any home hi-fi. Hooker sang dramatically,

swinging for expression between loud and whisper-soft. He

strummed at his guitar with that signature John Lee Hooker

beat. Intimacy, rhythm, and absolute clarity dominated the

experience. Hooker’s singing voice had throat and lungs. His

vocal inflections were roller-coaster rides. Wow!

What a recording! What a speaker! What a completely

memorable high-fidelity moment.

Compared to the KEF LS50

Few if any 21st century speakers have been anointed as

classics; the moderately priced KEF LS50 ($1499.99/pair)

has achieved that status. It is so effectively balanced and

well-executed a design that it does virtually everything

right—except move air and make low bass. Comparing the

LRS to the high-functioning, overachieving KEF was a must.

With the LS50s, driven by the Pass Labs XA25 amplifier,

I started by listening to Buddy Holly’s Down the Line: Rarities

(44.1/16 FLAC, Decca/Tidal) and was surprised at how

dense and resolved the music sounded. On “Buddy & Maria

Elena Talking in Apartment,” I was surprised how clear

Maria Elena’s voice came through: I got that really close in-

the-room-with-Buddy feeling. I started thinking, Who could

want anything more? Then, without my permission, Tidal’s al-

gorithm bot played Chuck Berry’s “Promised Land” (single

audition in an unknown system. As I experimented with
amplifiers and positioning, I realized the LRS could sound
anywhere from hard and shouty and lean to thick and slow
and soft. It takes patience to set them up just right!

Driven by the PrimaLuna ProLogue Premium
When the new Magnepans arrived, I removed my No.2
daily-driver reference speakers, the Harbeth P3ESRs, and
connected the LRSes to PrimaLuna’s 35Wpc ProLogue
Premium tube (EL34) amplifier. I imagined the PrimaLuna
would choke somewhat while trying to flow extra current
from its 4-ohm taps. But it didn’t. Bass wasn’t Thor’s ham-
mer, but guitar picking and string strumming brought me
copious detail-charged pleasures. This was a sweet, elegant-
sounding combination that really let the music flow. I found
it extremely enjoyable. I suspect, though, that many of you
would find it too tubey-sounding: Its chief weaknesses were
lack of bass punch and transient snap.

Driven by the Pass Labs XA25
Even with low-feedback tubes, the Little Ribbon Speakers
demonstrated an uncommon level of uncolored detail and
clarity. But the full measure of this naturally rendered clarity
was not exposed until I connected the famously transparent
Pass Labs XA25 stereo amplifier ($4900).
At the time I switched from the PrimaLuna amp to the
Pass Labs, I was reviewing fancy phono cartridges—and im-
mediately, on every black disc, I was hearing stuff I sublimi-
nally knew was there but never actually noticed. I heard
new coughers in audiences. I spotted a squeaking church-
bell support. The backs and sides of soundstages became

pattern, this sensitivity can’t be directly

compared with that of a conventional

box speaker—the dipole emits as much

sound to its rear as it does to the front.

Even so, the LRS will not go very loud

with low-powered amplifiers.

Magnepan specifies the LRS’s nomi-

nal impedance as 4 ohms. My measure-

ment of the speaker’s impedance mag-

nitude (fig.1, solid trace) revealed that

the LRS behaves more like a 3.33-ohm

load, with a minimum value of 2.8 ohms

between 400 and 600Hz. However, the

electrical phase angle (dotted trace) is

very low; the LRS behaves almost like a

pure resistance. This loudspeaker will

work well with amplifiers that have no

problem driving 4-ohm loads.

Turning to the LRS’s measured

frequency response (fig.2), the

proximity effect mentioned earlier

can be seen. The speaker’s farfield

output rises as the frequency drops

from 500 to 300Hz, while below

300Hz, the response measured in the

nearfield rises precipitously. In part,

this rise in the midbass will be due to

the nearfield measurement technique,

which assumes that the drive-units are

mounted in a true infinite baffle. But it

is also due to the panel’s fundamental

“drum-skin” resonance, which tends

to compensate for the fact that with

a dipole speaker the reflections of the

speaker’s backward-firing sound from

the wall behind it will cancel the front-

firing sound below a frequency that

depends on the panel’s size.

Higher in frequency in fig.2, the

black trace shows the Magnepan’s

farfield response, averaged across a

30° horizontal window centered on

the middle of the panel in front of the

tweeter section. (With the backward

tilt of the panel when supported by its

stand, this would be the listening axis.)

While the speaker basically offers an

even frequency balance from 500Hz

to 19kHz, an octave-wide, 7dB-deep

suckout in the presence region will

both affect the measured sensitivity

and make the LRS sound “polite.”

However, after I picked up the Mag-

gies from Herb Reichert’s Bed-Stuy

bunker, he suggested in an email that

“When you do your LRS frequency-

Fig.3 Magnepan LRS, lateral response family at 50",

normalized to response on midpanel tweeter axis,

from back to front: differences in response 90–5°

off axis on tweeter side, reference response, differ-

ences in response 5–90° off axis on woofer side.

Fig.4 Magnepan LRS, vertical response family at

50", normalized to response on midpanel tweeter

axis, from back to front: differences in response

15–5° above axis, reference response, differences in

response 5–10° below axis.