Summary:
This is a follow-up to my prior review of the NSM Model 50 loudspeakers. After spending some time experimenting with speaker placement, I have a different impression of the low-end capabilities of the Model 50s. Although I have now moved my loudspeakers to a less-than-convenient location in my listening room, the bass response, particularly extension, has improved substantially. My speakers now each reside about 8 inches from their long-standing "original" position (about 7 inches left/right and 4 inches forward), and they interact better with the room for more natural bass response. Using a test CD, my Model 50s produce strong bass at the 40Hz tone and - given that they are sealed enclosures with a mild roll-off curve - produce workable energy at 32Hz. Even at 25Hz, my Model 50s are still producing clean bass, although it is quite limited in volume. Overall, the bass response below 125Hz is a bit smoother and appealing than before. In real-world listening, this new placement gives the Model 50s a warmer, more enveloping sound without compromising their appealing bass transient speed.

Despite its rather small enclosure, especially in the width and depth dimensions, its reasonable sensitivity - I drive mine easily with a 35wpc amp - and its lack of a vented port, the Model 50s can produce a surprising amount of tuneful, articulate bass. The small enclosure makes the Model 50s easy to live with, the sensitivity makes it easy to drive and the sealed box design gives it a natural, musical sound. The fact that the Model 50s can also fill the room with a strong low-end foundation makes this an even better loudspeaker.

My time with the Model 50s is now beginning its fifth year. What I really like about them is how they manage to avoid any glaring sonic faults. While I will buy a better (and more expensive!) loudspeaker in time, nothing about the Model 50s makes me want to speed that process. I simply enjoy how they reproduce music. I'm surprised we haven't heard more things in the audiophile press about this small manufacturer!

Summary:
I have owned these slender tower loudspeakers for three years and am completely familiar with their sound. The NSM Model 50s are a two-way, three-driver sealed-box design, using 2 6-1/2" polypropylene bass transducers and 1 1" soft-dome tweeter (I belive a VIFA unit), in a MTM (or D'Apollito) array. The loudspeaker measures approximately 41"H x 9"W x 10"D and is available in a matte black or hardwood finish. My loudspeaker set is made from rosewood and is very attractive and has a nice, solid sound when rapped with the knuckles. The Model 50s stand on an integrated sand-filled base, which also holds the sealed minimalist crossover network. These fine pieces each weigh 60 lbs, which seems massive for their modest size. They also feature 24K bi-wirable binding posts. Physically, the Model 50s are very solid, attractive and are suitable to many domestic environments. They are made in the USA.
The Model 50 is positioned as a loudspeaker that images like a mini-monitor and has the bass response of a subwoofer. Overall, their sound is much like a mini-monitor, with a bit more extension and a grander musical soundstage. I would not call their bass response equaling that of a subwoofer. Since the Model 50 is not ported, ultimate bass extension is limited. I have managed to hear solid frequencies as low as 32Hz in my listening room, but placing the Model 50s to produce deep bass in the room (meaning close to the back wall) compromises their ability to image, which I consider more important. What you give up in extension, you gain in transients, which are reproduced to awesome effect with the Model 50s. Everybody seems to crave extension, but I personally find great transient performance more spine-tingling. You can get both, but you have to spend a bit more $$$. Kettle drums and other dynamic bass instruments are given spacial defintion, not just one big "boom". Because the Model 50s gain an extra air-moving woofer over a small mini-monitor design, the scale of large instruments is generally preserved. The NSMs also reproduce the pace and rhythm of music. They do not stumble when the going gets busy. Overall, the low-end of the Model 50 is tight, articulate and clean, never boomy or distorted. The bass is more British than American, if you are familiar with this concept.

Probably the best feature of the Model 50s (and other NSM speakers) is the palpable, uncolored midrange. The sound is immediate, with remarkable transparency and clarity. Voices, particularly male, are reproduced without chestiness or boxiness. While the midrange is forward and vibrant, it never becomes weary or fatiguing, an observation that can be extended to the entire speaker. Much of the midrange's performance can be attributed to the solid interior-bracing. While the Model 50s aren't in electrostatic territory, instruments are capable of floating off of the speaker, as if they are suspended in three-dimensional space. This is a good box design. Acoustic guitar literally comes into your listening room and "floats". I concur with NSM that the Model 50s can image like a mini-monitor.

The Model 50's top-end is a just slightly sweet, smooth, with good detail and forever listenable. The "presence" region (approx 2KHz-4KHz) is slightly emphasized and contributes to the speaker's open sound. The soundstage is both high, wide and deep and seems naturally proportioned. The NSMs crave high-quality material because they can reproduce sound faithfully. Ordinary pop music just doesn't make these speakers shine as much as they should. Because of their good resolution and natural accuracy, the NSMs reward the listener when given a high-quality source. They also do not sugar-coat a poorly recorded album. You'll hear the warts. This is appropriate for a high-end product.

Natural, accurate and listenable are three words that come to mind when describing the Model 50 as a whole. Music doesn't seem forced, it just comes out. The sound isn't analytical, it's enjoyable, but yet not overly smooth and washed. I'd call the NSM's sensitivity average, though they seem to like a good dose of power. I have been doing fine with a 35wpc amplifier, but my loudspeakers are in a smallish room and don't require more volume/power. 150wpc is not out of the question for maximum performance and volume. Generally, the Model 50s do not have any characteristics that are light-years ahead of other similarly-priced models. OTOH, they do not have any faults that will spoil the pleasure of listening to music. They are very competent, without flash or other hi-fi pretensions; they are very musical speakers and likely will provide years of enjoyment. If you purchase the Model 50s, you will likely own them for years like myself because of their listenability and musicality.