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NHT Classic Four Floorstanding Speaker Sound Quality Tests

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Initial Listening Impressions

Tonally, the thing that strikes you upon first listening is the overall neutrality and understated quality to the sound. These are not speakers that are going to reach out and grab you with low-end drama or high-end sizzle. Given the aluminum drivers and the clichéd subliminal reaction many listeners have when they see metal drivers, it would be understandable to expect the Fours to have a steely, analytical character to their sound. However, this was not the case at all. They immediately conveyed a smooth, neutral, relaxed character, a trait that never diminished during the entire time I had them.

The bass was solid and satisfying on these speakers.

The bass end was solid and satisfying, but not quite what NHT’s description and specifications led one to think it might be. NHT claims a low-end extension number of “27 Hz,” but that number is given without any “dB down” qualifier. -3 dB? -6 dB? -10 dB? I’m sure it “responds” to a 27 Hz tone, but the lack of specificity in NHT’s bass end response number is quite surprising given the overall serious engineering tone and direction of the company. In any event, my reference speakers are large 4 cu. ft. sealed floor standers with dual 12-inch woofers in each cabinet. That’s roughly 150 sq. in of woofer radiating area per side compared to the NHT’s 65 or so.  Over twice as much in a lower-resonance system.

Their rated 3dB-down point is 28 Hz. With room gain, a sealed system’s very mild 12dB-per-octave rolloff (vented systems like the NHT roll off the cliff at 24 dB per octave), and just a teeny-teeny-weeny bit of bass boost, my reference speakers are absolutely dead flat to about 20-22 Hz in my room. I can assure you, the Classic Four’s bass impact and extension were not even in the same universe as my reference speakers.

But…..that’s not to say that the Fours were in any way deficient in bass or unsatisfying to listen to. Quite the contrary: Their bass is solid, musically full and warm. Tight, quick, articulate and detailed. The Four is the proverbial poster child for perfectly-done vented bass: not “one notey” in the slightest, not slow or sluggish, it didn’t fall prey to any of the pitfalls of poorly-executed reflex systems. I just think that NHT needs to put a realistic qualifier on that idiotic “27 Hz” number and do some prudent expectation management. By ear, I’d say these things are good to the low-mid 40s and likely down at 27 Hz in the low double-digit dB range. That’s very nice bass response. Just don’t tell me it’s “27 Hz.” I know 27 Hz. 27 Hz is a friend of mine. And NHT Classic Four, you’re no 27 Hz. 

Regarding 27Hz Comment: This reference is from one of the most famous political debate exchanges in American history: the 1988 vice-presidential debate between grizzled veteran Lloyd Bentsen and the very young Dan Quayle. Quayle tried to draw a parallel between himself and the youthful, dynamic John (Jack) F. Kennedy, when Bentsen cut him off and said, “I knew Jack Kennedy. Jack Kennedy was a friend of mine. And Senator, you’re no Jack Kennedy!”

NHT4 Brochure.png

NHT Classic 4 Manufacturer Specs (note: no tolerance specified for frequency response) 

Manufacturer’s Comment: We have the impedance curve available so that you can see that the system is indeed tuned to 27Hz (27.6Hz).  Bass output is highly room dependent, so some experimentation with location and listening position is called for.  In our listening room, output below 40Hz is quite evident (with organ recordings, some of Roger Waters music, a number of songs with synth bass parts).  Also, make sure that the straps connecting the 2 sets of binding posts are connected tightly (they sometimes work loose in shipping).

Audioholics’ Response: In our listening room, compared to a sealed (12 dB/octave rolloff) reference system with a well-known and well-documented LF -3dB point of 28Hz, the NHT Classic Fours did not have anywhere near the same depth and impact. Considered on their own, the NHT’s bass was unquestionably excellent in all respects, but it wasn’t anywhere near the equal of the reference speakers. NHT can call it “27 Hz” all day long if they like. Not in my room it wasn’t—in the same physical position, too, so this was ‘apples to apples.’

Here’s my totally unsolicited design/marketing advice: I think the Classic Four would have better achieved its design aim of a superb “three-way bookshelf speaker sitting on its own subwoofer stand” if it was just a bit larger and had a 12-inch side-firing woofer with legitimately deeper extension and greater LF impact instead of the current 10-inch driver. The way it is now, it’s not sitting on a “subwoofer” stand; it’s sitting on a “woofer” stand. I think a 12-inch-based Classic Four Plus at around $1,500 ea. would be a far stronger product than the current Four at $1,349. And to re-emphasize again: I like the current product a lot.

As I mentioned earlier, a correctly-designed 4-way speaker can have exceptional deep bass, the woofer will not intrude into the vocal region (which is handled by a separate ‘mid-woofer’), and the mids and highs can be reproduced by smaller, faster drivers with exceptional dispersion. The Classic Four takes full advantage of the potential of a 4-way approach to achieve these goals: The vocal range was pure and uncolored, totally unaffected by the deep bass. No woofer that goes up to 300-800 Hz (as in a conventional 3-way) is completely free of interaction between the deepest bass and the vocals. A good 4-way gets around that completely. By the same token, if ultra-wide dispersion is the goal, which, admittedly, it often is not these days, for purposes of imaging or localizability,a 4-way design allows the engineer to use drivers that have the widest possible dispersion in their passbands. The typical 5 ¼-inch midrange in a conventional 3-way speaker crossing over at 4-6 kHz to the tweeter is already beaming pretty badly by the time it’s relieved of its duties. Not so in a well-engineered 4-way: the dispersion is broad and uniform all through the frequency spectrum, giving the speaker a very consistent tonal balance throughout the room, at all listening positions.

Listening Tests

I have used many of the same discs for many years to test loudspeakers, not simply because they’re well-recorded CDs, but because I know them so well that they are reliable test devices that I can compare from speaker to speaker and be confident of the differences I’m hearing.

CD: Donald Fagan—The Nightfly
A nicely-recorded pop CD, with Fagan’s/Steely Dan’s trademark clarity, solid deep bass and crisply-etched vocals. The Classic Fours presented the cuts with transparency and excitement, accompanied by a strong, clean bass line. There are some very deep bass tones on The Goodbye Look, which the Classic Four rendered with more than respectable weight.

CD: Jennifer Warnes—The Hunter
This is an over-played, over-used, totally synthetic-sounding and too-heavily processed pop recording. But the opening cut, Rock You Gently, is so chock full of quantifiable, repeatable audio tidbits that if one overlooks the questionable production merits of the song, its sonic traits do provide some valuable information. The recording has a very deep, strong bass line throughout and some sharp snare drum <cracks> that punctuate the background. But it’s at the 2:33 mark of the track that things get interesting. I’d used this cut for years to test how well a speaker can simultaneously deliver clean, low-distortion deep bass (long excursion), while keeping the female vocals clear and preserving detailed highs. It’s a tough test for most speakers. And if a speaker doesn’t have subterranean bass response on its own, it’s a good test to see how well the speaker will ignore the very deepest bass that it can’t reproduce anyway while still doing a good job with the rest of the spectrum. I’d gone years listening to this cut on all the speakers I’ve voiced without realizing that at 2:33 there is a sustained low-20s Hz tone (about three seconds long) that just rises up from the floor and absolutely dominates the room.

The Classic Fours shined on these tracks, and their highs were as solid and well-reproduced as one could ask for.

Very few full-range speakers will reproduce this tone, since most full-range speakers—even quite excellent, expensive ones—will only respond, honestly, down to 35-40 Hz or so. My reference speakers are sealed systems with dual 12” woofers (with a very shallow 12 dB/octave rolloff), rated very realistically down to -3 dB @ 28 Hz. With a little room gain by virtue of being within a foot of the wall behind them, per the manufacturer’s recommendation, they are quite flat in my room down to the lower 20s. At the 2:33 mark of this cut, fed with 400 distortion-free watts, they make dogs cower and babies cry.

The Classic Four, at 2:33, projected a sense of power and depth that all on its own was pretty impressive. They didn’t overload. They didn’t chuff. They didn’t emit stressful “Help! Turn me down!” noises. In direct comparison to the reference speakers, they came up short, but all on their own, they were pretty darned good. I couldn’t help thinking to myself that if they had a gutsy 12-inch woofer instead of a 10, in a slightly larger cabinet, for about $150 more, these would really be something….

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 Rear-Facing Rectangular Vent

CD: Kurt Elling—Dedicated to YouDedyou.jpg

This is a superb live recording of jazz vocalist Kurt Elling backed by a big band featuring Ernie Watts on tenor sax and Lawrence Hobgood on piano. The first track, All or Nothing at All, starts off with a string quartet intro, beautifully recorded. Played on top-flight equipment, it is almost believable that a string quartet is, in fact, right there. After that intro, there is a piano run ending in a single very high note, struck quite hard. It’s a great test of a tweeter’s power handling and ability to project a three-dimensional, organic sound into the room without being ‘spitty’ or ‘hissy.’ The Classic Fours shined here, and their highs were as solid and well-reproduced as one could ask for.

Elling has a great voice, deep and resonant, with tremendous range, power and control. He is a master vocal stylist and his ability to go anywhere he wants and always return home is without equal among today’s singers. If you’ve ever seen him live, you know how he quickly captures the audience’s attention, gains their complete confidence that he’s in total musical command, and then takes them along for the ride. This recording is mixed with Elling in a very solid center image, and the Classic Fours convey that without equivocation. Elling is front and center, and the band is behind him and wide to each side. There was never a time when the sound was thin or lacking in any way. Instantaneous A-B switches to my reference speakers revealed that deeper sound was there to be had on the recording, but listening to the Fours alone never left you feeling as if something was missing.

CD: Ariel Ramirez/José Carreras—Misa Criolla

 Wonderful Phillips recording of classical/vocal music, the first two cuts really test a speaker’s ability to resolve low-level detail and present a three-dimensional sonic landscape. Carreras’ voice is pure and delicate, and is accompanied by very subtle tympani strokes in the background. Properly reproduced, these strokes convey a sense of the mallet head hitting the drumhead and the resonant tail from the strike carries on long and quietly fades off behind the vocal. The Classic Fours proved up to the task of speaking quietly, but with precision and authority. Lesser speakers smear these details together; the NHTs kept things clearly delineated and focused, but without artificial hype or an exaggerated top end. This is a tough test disc, highly recommended.

misacriola.jpg        dianeschuur.jpg 


Diane Shuur & The Count Basie Orchestra

The first cut, Deedles’ Blues, is a rollicking, gutsy, full-blooded big band jazz vocal. Ms. Shuur’s voice is not exactly cut from the Cloth of Subtlety, if you catch my drift. And since this is a GRP recording, everything is just a bit overdone, a little larger than life. On second-tier equipment, things can degenerate into a screamfest pretty quickly, prompting a hurried lunge to turn down the volume control. First-rate gear presents this cut with lifelike verve and excitement, not with harshness and edginess. The Fours handled this very well, and the expected trace of midrange nasality that I’ve endured on many otherwise fine speakers never materialized on the Fours. I braced myself for it, but it never came. What a relief.

 

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Recent Forum Posts:

ichigo posts on June 01, 2018 20:10
I think the NHT Classics were unbeatable early on…but the street price went up over 50% after the recession, a real shame, which totally changed the speakers they were competing with.
DigitalDawn posts on May 23, 2018 08:36
Shalmaneser, post: 1249767, member: 67624
You mean there's life after NHT? Where does one go for better price/performance?
It's not easy to find better speakers for the price. But speakers are often a personal taste, so I'm sure there are other Brands/Models out there that folks would like. I was close with the original owners (Chris Byrne and Kenny Kantor) of NHT. Great guys.
TechHDS posts on May 22, 2018 15:54
ADGT, As usual I over looked the Thread, goes back to 2011, very old Thread. Gene, done made his mind up long time ago on which 3. Bad habits are sometimes hard to break I gotta start reading the dates when Threads are posted. I forget just how Oldsome of you old timers really are.

Mike
AcuDefTechGuy posts on May 22, 2018 15:38
I must have missed this thread completely. But regarding the bass, I recall someone (Home Theater Magazine or SV) setting the Classic Four as “active” or at least “partial active” bass by using a separate external amp and crossover and removing the metal jumpers from binding posts. This does not remove the internal XO, thus I mentioned “partial” active. But the external amp and XO powered the woofers. And this would produce lower bass Frequency. So the 27Hz is probably with the ext amp and XO powering the woofers.
Shalmaneser posts on May 22, 2018 09:33
DigitalDawn, post: 1249755, member: 78241
I used to own 3.3's – great speakers with their 12" side firing drivers. I ended up selling them to a guy in Australia about 13 years ago.
You mean there's life after NHT? Where does one go for better price/performance?
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