Apogee Caliper loudspeaker Page 3

It's not all cordon bleu catering, though. In addition to the potential for veiling in the lower mids, the low bass appears continually to be on the verge of being overcooked. This is not a problem with most recordings, as there is seldom sufficient subterranean energy to lead the panels astray. Occasionally, however, a recording happens along that is ideally suited for provoking misbehavior. The Reference Recordings Church Windows LP, for example. With the speakers driven by two Audio Research D-250s (see later), Side Two is cruising along in the mid-90s, spl-wise, without sounding too loud. Respighi then adds his deep organ pedal notes: the diaphragms attempt to go down through the gears to cope with increased load but rattle against the endstops around 102dB (flat, peak) (footnote 4), and one is left with the sense of having witnessed something distasteful. Or the ridiculously overdone bass note at the end of Tina Turner's "We Don't Need Another Hero" 12-incher. Peaking at a measured 104dB in midbass caused all manner of rattles. Such lack of control makes an Englishman feel uncomfortable.

At the end of the review period, I begged and borrowed the pair of D-250 Servos that JGH had reviewed in Vol.9 No.5. The first configuration was to use one D-250, driving the Calipers biwired as before from the 4 ohm taps. The dynamics were now increased over the Krell, but the lower midrange/upper bass veiling was more noticeable, being cloudy, and the upper midrange and lower treble became more forward in character, at the expense of the sense of depth. I know it's heresy, but there was a lack of coherence in the soundstage with the D-250 when compared with the Krell.

I then tried biamping the Calipers with both D-250s, but in the time I had available failed to get the results anticipated. The dynamics were, well, wonderful, the contrast between very soft and body-shaking loud approaching the live experience; the midrange became less forward than with one D-250, but there was still an overall lack of clarity. This was with one D-250 driving both bass panels and the other driving the tweeters. I scratched my head...Aha! I reached for my screwdriver. I drank it in one gulp and changed the wiring arrangements: now, each D-250 was driving a complete Caliper.

Better. Awesome, even. But still not right.

I will report more on this perplexing subject in a future issue.

Taking soundings
The last task before turning thoughts into printed words was to run a quick set of measurements. The impedance was more benign than that of the Scintilla: running between 8 and 14 ohms below 200Hz, it dropped to 3 ohms by 1kHz and rose gently to 6 ohms by 20k. Nothing there, unfortunately, that would explain the mismating with the D-250. The sensitivity appeared to be 4dB or so below that of the Celestion SL600, but this would be helped in-room by the typical dipole speaker's dispersion.

Taking a spatial average of the soundfield at the listening position with pink noise proved instructive: surprisingly for a panel speaker with such a small diaphragm—smaller, for example, than the Martin-Logan CLS—the 31.5Hz band was the highest in-room, the trend then being for the response gently—and very smoothly—to slope down all the way to 20kHz.

The fundamental woofer tuning of the earlier Apogees had quite a high Q, but Leo Spiegel has gone for a broader tuning with the Caliper. The woofer level is a little boosted, however, compared with the tweeter, which would explain why I ran into trouble with the deep organ notes on the Church Windows LP with the D-250. To ask for very high levels of ultra-low bass with an amplifier that has a rising output impedance at these frequencies will lead to a lack of control. The generous woofer balance will also allow bass problems to be clearly heard in the rest of the chain: I suspect that the upper-bass veiling was due, in part, to the LP12/Ittok's richness in that area.

Tonally, the Caliper's midrange and low treble were similar to the SL600, but above 3kHz there was less energy. Dull or recessed cartridges, or those with excessive low bass, would not be a good match with the Caliper. But use a suitable cartridge—the vdH MC10 would work well, I think—in a tonearm with superb bass definition, like the SME V, and these babies would really sing.

Measure for measure
"But this time with a little dedication..." sang Joan Armatrading in that "Love and Affection" track, and a little dedication is what you need to get the most from a speaker like the Caliper. Although it is amplifier-fussy—in the sense of requiring large amounts of voltage and amperage simultaneously— to a much lesser extent than the Scintilla, chameleon-like it manages to take on the sound character of the amplifier and cables with which it is used, to a larger extent than I have before experienced from a speaker.

Problem areas for the Caliper are the slight veiling in the upper bass/lower midrange (the extent of which will be very amplifier- and cable-dependent), the tendency for the low bass to be a little too rich, and the slight lack of HF air. Otherwise, the Calipers present the music with a midrange transparency rarely heard at this price level.

With a relatively neutral solid-state amplifier—I liked the Krell KSA-50, and Apogee also recommends the new $995 Belles 400, two Eagle 2As or Adcom GFA-555s—the Caliper is perfection on a small scale, exquisite if a little reticent above 120Hz, adequate below, transparent, but lacking bass authority and control.

There is a danger with a high-end loudspeaker like this, priced almost within the bounds of reality, in that owners of systems based on inexpensive front ends and electronics will be tempted to buy them. Certainly there should be no problems using the Calipers with relatively inexpensive solid-state amplification. However, they demand to be used in a system with an at-least-good LP player. The Linn is probably not a good choice; its own area of weakness, the upper bass, coincides with that of the Caliper. But SOTAs, VPIs, and Oracles would be fine.

With a compatible amplifier, the magic the Calipers weave on voice, their holographic, unforced, imagery, and the uncolored upper midrange and treble, add up to no problems with passing the goose-bump test.

Footnote 4: Apogee's specification indicates maximum levels of 105dB (C-weighted) will be attainable, which ties in with this level of bass. Apogee does say, however, that if the perforated plate supporting the magnets is very slightly bowed, bass excursion will be reduced. Current-production Calipers are checked for flatness.—John Atkinson
Apogee Acoustics
438 Glenview Road
Glenview, Sunshine Coast
Queensland 4553, Australia

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