I have to tell you right here, at the outset that I'm in love. From the first moment I plugged these speakers in and gave them their head, I knew I was in the presence of something truly special, even extraordinary...
Mistakenly, I first thought the Apogee Caliper Signature was a value-added model designed to run in parallel with the Caliper but at a slightly higher price. It isn't so, though the higher price is real enough. The old Caliper cost £2800 and the Caliper Signature costs £3150, an increase of about (clickety click) 12.5 per cent, though I suppose if you need to ask, you should have turned over by now anyway. In fact the Caliper has been discontinued altogether and is replaced rather than supplemented by the Caliper Signature, which is now the cheapest loudspeaker in the Apogee range, I'm sorry to say.
Existing Caliper owners haven't been left out in the cold. Anyone wishing to upgrade to the Signature spec can do so through their dealer, but they should be warned that it wouldn’t be cheap - the bass unit, tweeter and crossover must all be changed. I applied to Absolute Sounds, the UK importer and distributor for Apogee, for a price. They've promised a reply in time for the Comeback pages. Don't lock for bargain deals on this; I understand the replacement hardware is supplied at cost, as a service to existing customers. Nobody is stitching you up on this.
At first sight, the Caliper, in becoming the Caliper Signature, doesn't seem to have altered much. When I unboxed the review pair, I was aware only of some subtle changes in colour. The test samples are silver and grey Nextel, but you can have anthracite (or are mine anthracite?) or taupe. I wonder if the Editor would put up a river to anyone who can explain what taupe is?
This seems like a good moment to dive into a quick recap of what Apogee are all about and how the Caliper fits in. Apogee are all about full-range ribbon transducers, of which I believe they are the only quantity manufacturers in the world. Ribbon tweeters exist in reasonable profusion, but bass ribbons are an altogether different kettle of fish. It's not that there is any conceptual difficulty with ribbons, it's just that they're horrendously labour-intensive to build, and tend to be ferociously difficult to drive - and the easier to drive you make them (for example, by using matching transformers) the worse they sound. The other major point about Apogee speakers is that they are flat panel radiators, with a near-dipole radiation pattern.
In a general vein I might also mention that, both in concept and in execution, Apogee speakers represent a very considerable feat of imagination, and in the early days were an act of blind faith. From this you will appreciate that they're not, and probably could never have been, Made in Britain, home of the Greatest Loudspeakers on Earth Ltd. No sir, They come from Randolph, Massachusetts in the United States of America.
With cost-absolutely-no-object monsters like the Apogee Divas, the minimum of compromises are the order of the day. The Divas present a 1ohm load** (see bottom), and have an insatiable desire for amps and volts. They can be used with the bigger Krell power amps, which seem to revel in this kind of challenge. But precious few others amps are suitable, which makes these speakers a tad less than practical for many people, even without taking into account the acres of room they like to work into.
As the cheapie in the range, the Caliper was designed to work happily with a broader cross-section of amplifiers. It was also smaller than its stable mates, which made it more suitable for smaller rooms, and more pleasing visually since although Apogees are thin speakers, the bit you see when listening is wide and tall.
But everything is relative. The Caliper (the old Caliper I'm talking about) was still a pig to drive and incredibly inefficient. It never seemed to be happy with anything less than a Musical Fidelity A370 or a Krell KSA-80 (or the KSA-100 from the old range - the 50watt Krell wasn't quite up to it) providing the muscle. And £3,000 is only cheap for Apogee you can almost buy two pairs of Isobariks for that, and convert one pair into walk-in wardrobes, his and hers.
The Caliper Signatures look like a couple of inwards leaning, upended trapezoid which have been squashed inwards at the outside top corners by a monstrous force. The bass driver is a trapezoidal corrugated ribbon, stretched from side to side, the variation of width with height above the ground helping tune the driver to a broader, shallower fundamental resonance. The tweeter ribbon is a long strip positioned on the inside edges of the mirror-image pair. The crossover is passive but optionally bi-wirable. In my view it is nothing less than essential to bi-wire this speaker - see later.
The development programme that produced the Signature was explained to me in the course of a long distance phone call with Leo Spiegal, the designer of Apogee loudspeakers. 'First I improved the electronic shaping circuit,' he explained. 'The near field response is very subtly shaped. A response 'hinge' is created around 1kHz, with output then dropping to about - 2.5dB by 5 or 6kHz. Output then rises again until it reaches nominal, which is maintained between 12 and 20kHz. This means output is slightly depressed in a region centred on 5 to 6kHz, but the acoustic far field response is very smooth and group delay is very low.
Another point that received attention was the acoustic baffling around the mid/ tweeter ribbon. Everything around the ribbon affects the way it sounds. I worked and reworked it to achieve a smoother and cleaner response in the midrange. I got where I wanted to go by fitting wood blocks of different dimensions on the back of the midrange/tweeter ribbons.
I also redesigned the bass ribbon. Impedance has been lowered from a little over 4ohms to about 3ohms, and the ribbon has been made slightly heavier, which is practical because the mass of the air load is so high in relation to the mass of the diaphragm that increasing it has a trivial effect. In combination these measures have led to an improvement in sensitivity of no less than 4dB. Apogee were ambivalent about the actual sensitivity figures, claiming difficulties in making the measurement. But it seems that the anechoic figure is slightly under 80dB for 1 watt at 1 metre, while the in-room figure is typically 86 or 87dB. That is still a low figure, but there's no questioning the Signature's increased sensitivity.
A few hints and tips. The first is to use the tweeter in its 'high' switch position not because the brighter balance is necessarily more appropriate, but because with the attenuating resistors in circuit the high frequencies tend to sound a little compressed and smeared, and also a little coloured. Then there's cabling. I bad some lengths of Linn loudspeaker cable available, and because of the speaker's voracious appetite for amperes I thought it would be sensible to use this high grade stranded cable in the bass leg of the system, with my normal Mission solid-core retained in the tweeter leg, where its fine resolving power would be best employed. The arrangement turned out to be a shambles, a complete disaster. The system sounded grainy and coarse, even in the midband and treble. Using solid-core stock throughout affected a complete cure.
Positioning is also extremely important. One aspect that must not be ignored is Apogee's instruction to dispense with toe-in. Readers will be familiar with the idea that listening to conventional speakers on different vertical axes has an important influence on the sound. In this case the drive unit orientation is switched through 90 degrees, with the tweeters on the inside rather than on top. Consequently the horizontal axis becomes of particular importance in the way the system gels in the crossover region. It only focuses correctly when listened to from well inside the tweeter position, the speakers firing down each side of the listener.
Moving on to the question of support, the old model used a rearwards facing outrigger on the base with a single adjustable pad-type foot. The new model has two such outriggers, both fitted with adjustable spikes. However, the speaker panel base has rubber feet, and it's these that the speakers hinge around. Although the new semi-spiked arrangement is a great improvement, it's still far from ideal because the amount of free movement of the baffle is still considerable. A suitable support would need a decent footprint - say, 30cm front to back and the same width as the speaker. It would also be spiked at each corner. It occurs to me that a suitable support could be made available on the aftermarket in the form of a simple spiked platform. Hint, hint, somebody.
Plugged into an existing system, in this case with a Krell KSA-200, DNM preamp and various CD and vinyl-based sources, the Signature replaced my standard Calipers. The differences were striking, and I'm already saving for the upgrade. First impressions were that the Signatures are much more sensitive, though further experiment showed that you still need an amplifier that doesn't baulk at difficult loads.
The Signatures also sound much livelier and smoother. The top end is sweeter and has a little more presence than before, while the midband doesn't quite throw itself in your lap in the way it could previously. They sound, not more distant exactly, but more relaxed and natural, yet without a hint of a loss of grip or resolution. Just the opposite. Bass reproduction is a constant surprise. It doesn't go quite as deep as a Tannoy DC3000, but it has the measure of most others. Above all it has tremendous resolving power. A typical example. On Bob Dylan's You're A Big Girl Now, from the seminal Blood On The Tracks album, I heard what sounded like involuntary foot stamping noises on hollow floors. I have never heard them before, and I don't think they were meant to be heard.
These are the bald facts about the Signature's sound, but they are not the experience, which is much harder to impart in a few well chosen sentences. Let's see if the following help, First and foremost, the Signatures sound comfortable - perhaps a better word is right - from the very first moment. The old Caliper was never so unobtrusive, especially when new. Second, and perhaps crucially, they exist thoroughly in the service of the music. Their brief does not extend to covering up. Shabby, grating strings that sound like a bow being drawn over the edge of an open baked bean can (oh, so you've got the same Compact Disc, have you?) are not going to be tarted up or smoothed over by the Signatures.
But when the sound is right, they won't conceal that fact either. They sound glorious on simple, open chamber music; are a delight playing rock music at 100dBA; and display superb grip, poise and separation when steering their way through the minefield that is the awesome first movement of Mahler’s Ninth.
Price: £3,150 Serial No: 11632
** The Diva is actually a 3 ohm load