The NSM Model 25 Speaker System

Ronald Carlen

NSM, a Long Island based manufacturer of dynamic speakers, currently has four models in their Standard Series, ranging from the Model 10 minimonitor to the four-way, floor-standing Model 75. They also manufacture the Model 15EXP subwoofer, which can be used with the Model 10s or Model 25s. NSM recently introduced its Master Series line of speakers, including the Model 10M mini-monitor, the Model 20M and Model 60M. The 20M is a point source design using a coaxial driver, while the 60M is a floor-standing, three-way, time aligned system. The company also manufactures two sand filled speaker stands for use with its smaller speakers. The Sandbag 30 is for use with the Model 10; the Sandbag 24 provides the proper listening height for the Model 25. The manufacturer supplied a pair of the Sandbag 24 stands along with the speakers for review.

All speakers in the NSM product line are built in carefully matched pairs, with individually adjusted crossovers and drivers. NSM states that this maximizes accuracy and imaging precision. The drivers are broken in for several hours and then matched before assembly. All crossovers are hard wired and hand soldered. No printed circuit boards are used in the speakersùthey even wind their own coils for the crossovers to insure consistency. The inductors are all air-cores, and the capacitors in the signal path are metallized polypropylene and mylar. 14 gauge oxygen-free copper wires are used for all connections inside the speakers. A five year warranty is provided on all models.

PRODUCT DESCRIPTION

The Model 25 is a two-way acoustic suspension system with a 6.5" bass/midrange driver and a fabric dome tweeter. Each matched pair of speakers is packed in one box, although there is no left and right designation The woofer's position is near the bottom of the cabinet, while the tweeter lies about halfway between the woofer and the top of the cabinet. This is an unusual layout for a small speaker since it leaves a relatively large gap between the two drivers. The cabinet is constructed of 1" and 3/4" anti-resonant fiber panels, yielding a very solid cabinetùa knuckle tap generates a dead thud with no apparent resonance. The interior of the cabinet is tuned with open-cell foam and Dacron fiber.

The speakers are rated flat from 35 Hz to 20 kHz +/-3 dB (measured at 80 dB SPL), with a rated impedance of 8 ohms and a rather low sensitivity of 84 dB. NSM admits that by keeping the number of components in their crossovers to a minimum, the efficiency of the speaker suffers. There is a double set of five-way binding posts recessed in the rear. This allows for bi-wiring or bi-amping of the speakers. Gold plated jumpers are also included.

The Sandbag 24 Loudspeaker Stands raise the speakers 24" off the ground. The center column of the stand is filled with packed sand, resulting in a very heavy, non-resonant base for the Model 25s. The stands include spikes that add another 3/4" to the height. Plastic putty is supplied to be used between the speaker and the top of the stand. The putty is first applied to the corners of the stand, then the speaker is pressed down into the putty. I used the stands with the spikes and putty in place as recommended by the manufacturer.

LISTENING EVALUATION
NSM founder Erol R. Ricketts brought a demo pair of speakers to a meeting of The Audiophile Society, and then later turned the speakers over to me for review. The speakers had been played many hours and were fully broken in. (NSM recommends 200 hours of break in time.) I did not notice any changes in the speakers over the extended period that NSM lent them for evaluation.

The manufacturer suggests placing the speakers on the 24" stands at least 2' out from the rear wall, 2 ' or further from the side walls and 8' apart. Since my room measures 11' wide by 17' long, I could not achieve the recommended separation between the speakers. After spending time trying different positions, I settled on a placement that was 4' from the rear wall, approximately 2' from the side walls and 6' apart. The listening position was 10' from the speakers. The most precise imaging and soundstaging was achieved with the speakers angled in approximately 1". Once satisfied with the placement, I spiked the stands to the floor for the remainder of the evaluation.

After connecting the speakers to my Threshold amplifier with XLO speaker wire, two things about the speakers were readily apparent. First, they are quite inefficient for a dynamic speaker; the speakers easily used the 200 watts per channel my amplifier could deliver. Second, there was an impressive amount of deep bass for an acoustic suspension speaker of this size. While the very bottom octave cannot be produced by this system without the use of a separate subwoofer, there was significant mid

and low bass output. In fact, in subsequent comparisons with other speakers of similar size and price, no other speaker achieved the bass output of the NSMs.

I played a wide range of material in evaluating these speakers: jazz, classical, rock, male and female vocal and piano recordings. Although I could achieve very realistic sound levels, the NSMs won't blast you out of the room when playing loud rock music. Overall I found the output sufficient for most listening, and I am sure many users would get satisfying output with a smaller amplifier than my own.

In comparisons with other small speakers, I noticed that the top end of the NSMs seemed to be slightly rolled off, resulting in a very smooth sound that was more recessed than the other speakers. This apparently caused the image to fall slightly behind the speakers. The smoothness was also apparent on female vocals, which were never strident or excessively sibilant. The smoothness of the speakers helped tame some older CDs that sounded harsh on other systems. This made the speakers pleasant to listen to over extended periods. I had the speakers set up in my room for several weeks and never experienced any listing fatigue.

The NSMs produced well-defined imaging from side to side, with clear separation between the instruments. The focus was more defined by toeing in the speakers, but this sacrificed some soundstage width. In my setup, I did not perceive the soundstage extending beyond the outer edge of the speakers. And it shouldn't the recording has just the right phase cancellations between the channels. In addition, I was not able to achieve extended depth in my listening room. However, I do not attribute this solely to the speakers, since I have had shallow soundstages with several speakers in my listening room.

Instruments retained their tonal character across the octaves, indicating a very good match of drivers and a seamless crossover. The speakers did an accurate reproduction of the saxophone (which is one of the harder instruments to reproduce, due to its complex harmonic structure) on "Over the Rainbow" from Jazz at the Pawnshop 2 (Proprius PRCD 9044), with no hardness to the sound. The mid bass reproduction was not as tight as some other small speakers, which was apparent on string bass. This may be attributable to a slight rise in the response in this region as well as the speaker's interaction with my listening room. The NSMs did a good job in producing the deep bass in "Fantasie in G Major" (Dietrich Wagler on the Silbermann Organ, Priory PRCD 332). While the bottom octave can't be reproduced by such a small speaker, the tonal quality and balance of the organ over the range the speaker could produce was excellent; when the speaker was driven hard with deep bass from the organ, it did not compromise the midrange or upper octaves.

While the NSMs can produce substantial sound levels with a good amplifier, they did not generate the strong impact from the dynamics contained in the various cuts of The Sheffield Track Record (Sheffield Lab 20). Some of the other speakers I used for comparison did a better job with the dynamics on this record, as well the lively" "Township" and "Celebration"" from Party by American Gramophone (AGCD102).

IN SUMMARY

The NSM Model 25s represent a very good value for the money. The smoothness, imaging, accuracy and definition of these speakers clearly outweigh the unfavorable attributes of low efficiency and slightly constricted dynamics. They produce a broader response more accurately than many speakers in the under $1,000 price range. The NSMs have a lot of competition here, but should be given a fair audition with matched sound levels. Although the equipment I used for evaluation is not all "state of the art," the purchaser of a system in this price range would not ordinarily be spending several thousand dollars on the associated electronics. In fact, these speakers could work well in a system with a powerful receiver. For someone on a limited budget who wants accurate reproduction from small speakers, the NSMs are an excellent choice. If they are included in a starter system with a receiver, they will perform quite well as the other components are upgraded. By adding a subwoofer, you can achieve a moderately priced full-range system.

The NSM Model 25 speaker system, $895 in matte black, $995 in

painted black ash wood veneer or oiled walnut veneer. 22'' H. x 9" W x 10" D. NSM Loudspeakers, P.O. Box 326, Garden City, New York 11530-0326. Phone 516-48682&5, fax 516-538-0933.

Associated Equipment: Threshold Stasis 2 amplifier, Krell PAM 1 preamplifier, Sony 707ESD CD player, VPI HW-9 Turntable with Syrinx tonearm and Kiseki Agaat Ruby cartridge, MIT PC Squared interconnects.