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While the bass drivers will normally be acoustically coupled to wall and floor, the cabinet's depth not only ensures excellent stability (to some extent unnecessary in view of the mechanical decoupling and horizontally opposed bass drivers), but also places the mid and treble drivers sufficiently far from the wall to avoid the most serious effects of reflection coloration. The main enclosure and its substantial, neatly styled, cast-alloy plinth is the "virtual mechanical earth" for this speaker system. Its lower 23" act as the main, 2.1ft3 (60-liter) bass cavity, but above that the cabinet…
The first time I heard the NBLs in my room, I was reminded of the wall-mounted drive-units by Tannoy (15" alnico-magnet dual-concentrics) I sometimes use. These drivers, flush-mounted in a structural wall and left unobstructed to their rears operate as true boxless infinite baffles, and are regular reminders of the limitations of normal loudspeaker enclosures. While the NBL doesn't share the same tonal balance of these wall-mounted Tannoys by any means, it does have something of the same "boxless" sound quality. This would seem to confirm the efficacy of that complex enclosure decoupling.…
I discussed the NBL's tonal balance with Phil Ward, who said that the speaker had existed in active form for some months before the passive version was finalized, and that the control settings arrived at under active drive provided a "target function" for the speaker's passive balance. It's my suspicion that an active system can get away with being more "forward" than its passive equivalent, simply because the absence of passive crossover components invariably makes the sound inherently cleaner. A slightly more restrained balance might be more acceptable in the marketplace.
Stereo…
Sidebar 1: Specifications
Description: Three-way, floorstanding, sealed-box loudspeaker. Drive-units: 0.7" cloth-dome tweeter, 5" paper-cone midrange unit with phase plug, two 8" paper-cone woofers. Frequency response: 25Hz-20kHz ±3dB in-room. Nominal impedance: 4 ohms minimum. Sensitivity: 92dB/W/m. Power handling: 150W (music).
Dimensions: 44.9" (1140mm) H by 11" (290mm) W by 19" (430mm) D. Weight: 90 lbs.
Finishes available: Black Ash, Walnut, American Cherry, Ebony, Beech, Santos Rosewood.
Serial number of units reviewed: Not noted, auditioning samples; 160627 (speaker),…
Sidebar 2: Associated Equipment
Because I normally use Naim electronics, I already had access to and was familiar and comfortable with the "manufacturer-approved" driving system for the NBLs. But because I still haven't managed to get my mitts on a Naim NAP500, I did most of my listening using a Naim NAC52 preamplifier and Naim NAP135 monoblock power amplifiers. Other amplification included Mana Stealth MA-1 monoblocks and a Bryston BP25/2X7B pre-/power combination.
Prime sources were Naim CDS II and Audio Note CDT-Zero/DAC 5 CD players. Vinyl replay was mostly via a Linn LP12…
Sidebar 3: Measurements
The Naim NBL's specified sensitivity is very high at 92dB/W/m, though this will be boosted 3dB by the speaker's 4 ohm nominal impedance. (That "W" in the specification is therefore actually equivalent to 2W). I measured approximately 89.8dB(B)/2.83V/m, which is still high. Fig.1 plots the Naim's impedance magnitude and phase against frequency. The former varies little, staying within 4 and 6 ohms over most of the audioband, with only a moderate phase angle. A good 4 ohm-rated amplifier will have no problems driving this speaker. A couple of small wrinkles can be…
Fig.4 shows the NBL's response on the tweeter axis, averaged across a 30 degree horizontal window to minimize the effect of position-dependent, and hence irrelevant, interference effects. Though it is very even, the entire treble is shelved-up compared with the lower midrange and bass, which is why PM commented on the speaker's bright, forward balance. As I've said, the NBL's low bass will be boosted by the Allison Effect, but this will leave the region between 300Hz and 600Hz depressed in comparison with the regions above and below. In addition, as PM found in his in-room measurements, the…
Vertically (fig.7), the tweeter's top octave gets hotter both above and below the tweeter axis, which is 34" from the floor, though a significant crossover-region suckout will be audible to standing listeners. But, as always, don't pass judgment on a speaker's balance unless you're sitting down.
Fig.7 Naim NBL, vertical response family at 50", normalized to response on tweeter axis, from back to front: differences in response 15 degrees-5 degrees above axis, reference response, differences in response 5 degrees-10 degrees below axis.
The Naim's step response on the…
February 2000—We are now comfortably past all the millennial hype, which, by New Year's Eve, really had risen to a nauseating fever pitch. But it's hard not to look back to the times, the places, and, most of all, to the faces and personalities that populated the last hundred years.
Johnny Thunders, Chesty Morgan, Bill Wyman, Wilt Chamberlain (tie), Jimmy Stewart, Leroy Neiman, Pol Pot, Jackie O, Winston Churchill, Alf Landon, Spike Jones, Ratso Rizzo, Wendy O. Williams, Ed Norton, Blaze Starr, Fred Garven (male prostitute), the clever and now-rich person who invented the CD opener, and…
Paul L. Althouse
SCHUBERT: String Quintet
Alban Berg Quartet; Heinrich Schiff, cello
EMI 66942 2 (CD). 1983/1998. Gerd Berg, prod.; Johann Nikolaus Matthes, eng. DDD. TT: 47:33 As I look back over the 75 or so new CDs I've heard this year, I see that reissues account for about half—and the more interesting half, at that. When this performance was first issued some 15 years ago, I thought it as fine as any I would ever hear. The balance between drama and lyricism was superbly struck, and the playing was beyond criticism. The performance overall is unrushed and deeply moving,…
SCHUBERT: String Quintet
Alban Berg Quartet; Heinrich Schiff, cello
EMI 66942 2 (CD). 1983/1998. Gerd Berg, prod.; Johann Nikolaus Matthes, eng. DDD. TT: 47:33 As I look back over the 75 or so new CDs I've heard this year, I see that reissues account for about half—and the more interesting half, at that. When this performance was first issued some 15 years ago, I thought it as fine as any I would ever hear. The balance between drama and lyricism was superbly struck, and the playing was beyond criticism. The performance overall is unrushed and deeply moving,…