NHTPro A-20 Studio Reference Monitor System.

Manufacturer: Vergence Technology, Inc., 3195 Park Road, Bldg. A, Benicia, CA 94510; [phone]; www.nhtpro.com

Price: $2,000

Source: Manufacturer loan

Reviewer: Tom Lyle

My advice is often solicited in regard to using studio monitors in hi-fi systems. 'Although it is not quite accurate, folks often think that using pro monitors will enable them to "hear what the recording session engineers hear." The low cost of some of these speakers also makes them very appealing -- some studio gear is very affordable, especially entry-level products. However, what we have for the subject of this review is not an entry-level product. It is a well designed and executed speaker/amplifier/processor system for use in professional recording studios, and the price reflects this.

No, T$S is not changing into a recording studio equipment magazine. However, I think the familiar letters "NHT" may entice even some seasoned audiophiles into thinking that the studio monitor option might be worth a try. Although NHTPro isn't exactly the same company as the audiophile speaker manufacturer NHT, in a way, it is. NHTPro products are designed and manufactured by Vergence Technology, formed in 1998 by the founders of NHT, and their factory is located right down the street from the "original" NHT. By the appearance of the speaker cabinets it may seem as if they share many of the same design principles -- they look exactly like the NHTs one may be familiar with.

The three-piece A-20 Studio Reference Monitor System consists of two mini-monitor-sized two-way speakers, a control amplifier, 20' balanced cables for connecting the speakers, and a removable 6' power cord. Rack mounting screws for the control amplifier are provided, and a schematic diagram for the amp and a cable impedance chart are also included.

When I lifted the amplifier out of its box I was surprised -- for its size, it was heavy! At 34 pounds, I thought it must be a very densely packed 3.5"H x 19"W x 13.25"D enclosure. This was confirmed when the cabinet was opened. Much of the weight is clearly from its transformers and internal heat sinks.

On the far left of the front panel there is a five-position control for the input sensitivity. Turning this knob all the way to the left mutes the system, and after that the readings are +11, +4, -3, and -10 dB. To the right of this is the boundary control. This compensates for either the reinforcement or decrease in low frequencies due to the speaker's position. The "0" position seems to bypass this control, and the bass output is attenuated by turning this five-way switch clockwise. The owner's manual states that each step lowers the low frequencies by 1.5 dB, most sharply at 50 Hz, with a decreasing effect up to 150 Hz. There is a diagram in the manual to help one determine which setting might be best.

To the right of the boundary control switch is the position control. This control adjusts the high frequencies to compensate for listening distance. The greatest setting, FF (far field), sets the treble output at its maximum level, and each setting below that attenuates the high frequencies by another 0.75 dB. A steep sloped cut starts at 20 kHz, and has no effect on the frequencies below 3 kHz. In the owner's manual there is a diagram that explains that the NF (near field) setting, with the most attenuation, is for distances of 1 meter or less. The MF (mid-field) setting is for listening distances of 2 meters, and the far field for distances of 3 meters or greater. It is also a five-position switch so one can dial in distances between the near and mid, and mid and far fields.

In the center of the front panel is the "system status" display. A small mode switch changes the display to indicate the average SPL, the line voltage, or the heat sink temperature. The SPL reading in the average sound pressure level at two meters that is derived from the amplifier voltage. The VAC is a reading of the AC power line voltage being supplied to the unit. The TMP or temperature reading of the output heat sinks is displayed in degrees Celsius, and the unit will automatically shut down if the heat sink temperature reaches 100 degrees. A headphone jack (but no volume control for the headphone output) is located to the right of the display mode switch, and on the far right of the front panel is the power switch.

The rear panel of the control amplifier has line inputs for both balanced XLRs and 0.25" phone plugs. These jacks are pretty much standard for pro music applications, and if RCA phono plugs are to be used in a home system, adapters will have to be used. One could hook up a mixing console, a preamplifier, or directly hook up a source with its own volume control. Speaker hook-up is by the provided balanced cables, and these inputs are located on the far left and right of the rear of the back plate.

The two-way speakers have a 6.5" treated-paper woofer in a cast frame, and a 1" aluminum dome, liquid-cooled tweeter. In a white paper published on NHTPro's web site, NHT and Vergence co-founder Ken Kantor explains that there are problems with the design of the majority of self-powered monitors in use these days. To make a (very) long story short, he says that these problems arise from a few factors, most being that the on-board amplifiers that are housed in the MDF cabinets of the speakers. This affects the sound of both the amplifier and the speakers themselves. The crossover network that is used, or not used, in these usually bi-amplified speakers is also inherently flawed. These problems have been addressed by housing a stereo 250 wpc amplifier in a separate control amplifier. The benefit obtained from the extremely short speaker cable runs that are used in self-powered speakers are compensated for by use of a unique arrangement of locating some components of the crossover network in the amplifier box and some in the speaker box. The cabling between them may then be precisely analyzed as a known element in the filter network, and so, he says, the speaker wires "disappear." NHT supplies their own speaker configured especially for their system. Pin/Conductor 3 of the XLR speaker cable is in the tweeter circuit, Pin 2 is the woofer circuit, and Pin 1 is the common ground. A very low-level phantom voltage is sent to power the speaker's LED. Because of the way the crossover is integrated into the design of the amplifier, the amplifier can only be used with the A-20s.

I listened to the NHTPro A-20 Studio Reference Monitor System in three locations: my home stereo system, my home recording studio (located in my basement), and a large professional recording studio. I'm sure most readers will be most interested in how it performed in a home system, which makes sense. This is an audio magazine, after all, and delving too much into the realm of studio electronics is not very relevant. And although the criteria are somewhat different for the studio than what they are for home stereo speakers, I will describe what I've heard in those situations.

My home system consists of a modified Oracle Delphi turntable with a Benz-Micro Glider cartridge mounted on a Triplaner VI tonearm. The digital front end is a Meridian 263/ 200 combo, the preamplifier a conrad-johnson PV12a, the power amp a Krell KAV-250a, and my reference speakers are Legacy Classics.

I set the A-20 speakers on 24" stands, as far away from the rear wall as I could (about three feet), and about five to seven feet apart. I usually had the sensitively on the control amp at either the +4 or -3 settings. This made it possible to bring my preamplifier's volume control to between the 8 and 10 o'clock positions for most of my listening, where it is set when using the reference power amplifier. I had already let the system burn-in for a while, so I started the serious listening sessions. The SPL readout hit a high of a little more than 90 dB on most material, by the way.

My listening position was a little more than the distance between the speaker's, and since the speaker cabinet's front baffles are not at right angles to the rest of the cabinet, toeing-in was not at all necessary. In fact, in their literature NHTPro claims at great length the benefits of having the speakers designed without parallel front baffles (although NHTPro is now marketing a monitor with a parallel front baffle). As with the NHT speakers I've heard before, the benefits were immediately apparent by virtue of their superb soundstage. Images were precisely located between and behind the speakers in their appropriate positions, and again, as with NHT speakers I have heard, this was the A-20s' greatest asset.

Other than that, their sound was just too bright. I know that some audiophiles like their speakers to be on the bright side, but the A-20s' sound also had what I can only describe as an etched quality. It was very difficult to judge the midrange by itself because of this harshness in the upper registers, but if I listened closely I guess it was rendered with a fairly natural sound. Male vocals sounded a little better than female, such on the masterfully produced Iggy Pop album, Brick by Brick. This Don Was production had Iggy's vocals placed perfectly between the two speakers, very lifelike (but not very lifelike when such was the intention of the recording).

But the exceedingly detailed treble made it seem as if there were a sonic magnifying glass held up to the recording. I could hear things I had never heard before, including some things obviously not meant to be heard. I don't mean imperfections in the recording, but artifacts such as overhanging "S" sounds, etc. This detail robbed all the subtlety that should be in the vocals. It may seem strange to speak of "subtlety" in Iggy Pop's voice, but it became immediately apparent that this was what I was hearing. His vocal style is underrated, and I have to admit that hearing his voice with that kind of brilliance was sometimes entertaining, even though it was far from natural sounding.

Unfortunately, switching the position control to the near-field setting in order to attenuate the treble didn't do much. With the maximum attenuation, it decreases the upper treble a total of less than 4 dB, and it didn't seem to make a significant difference.

I also tried some classical recordings, including the Naxos disc of Bruckner's Second Symphony. This excellent CD conducted by George Tintner has become one of my favorites of late, and I couldn't get through the first two minutes before turning it off. The strings were too bright, which added an artificial metallic sound to the recording. And as before, the overall sound was unnaturally detailed.

I'm not averse to detail. Lately I've been doing lots of listening through a Headroom headphone amplifier and Sennheiser HD-600s. Nothing that is on a recording is missed when listening through a good set of headphones. But the detailed sound I was getting from the A-20 system was very different. The Sennheisers sound very natural considering one is listening through what Jimi Hendrix once described as "ear goggles."

Using headphones through the controller's headphone jack did not lead to the same bright characteristics. It would be interesting to hear how the speakers sounded with another amp, but that wasn't practical. Besides, the speakers' crossover networks would have been for the most part bypassed. Not a good idea ...

Adding to this perception of brightness was that the bass was deficient. The speaker's acoustic suspension design was clearly meant more for sonic accuracy than musical enjoyment. There was a bit more bass when the speakers were moved close to the rear wall, but it was very detrimental to the rest of the sound. "The rest" being the soundstage, essentially, and it totally collapsed when the speakers were moved into this position.

The above comments may seem a bit harsh. But for $2,000, one could buy a very decent pair of small speakers and a power amplifier, and that's how I judged the A-20 system.

Now, on to my home studio. It is basically a post-production studio, since I don't do much microphone-based recording. Briefly, it includes a Tangent mixing console, multi-track analog and digital tape decks, computer-based Cakewalk and Sonic Foundry digital recording, editing, sequencing, and CD recording software plus associated hardware. For the last few years the monitor system has been a pair of PSB Stratus Minis powered by a Parasound HCA-1500a. I like the PSBs for many reasons, most of which are explained in Issue 58, and in Issue 65 I go into some detail about using the Minis as studio monitors.

One of the reasons I like them is because much of my listening is not near-field but from throughout the studio. The speakers are situated on either side of the mixing console where I do most of my mixing. The PSBs seem to handle near-field listening just fine. But I am just as often nearly eight feet away working my computer and electronic keyboard editing and composing. When doing this, I simply crank up the volume on the speakers.

I set the A-20 speakers on either sound of the console, and listened to some finished mixes of my own and some commercial CDs. This was unmistakably what these speakers were designed for. They were still a little bright, but for near-field listening with the controls set appropriately the treble didn't sound at all inappropriate -- detailed, yes, but this is how one would want to hear the material in a studio situation 99% of the time. These were fine studio monitors, and for the next few months they were an excellent tool for mixing, editing, and any other procedure I had where I needed to hear what was exactly on the recording. I could shape or set the level of the sound without having to worry I was missing anything.

Moreover, the treble and the speakers in general were not at all fatiguing. This is a very, very important quality because I might spend hours mixing and otherwise listening to one song or sound, and having the speakers drain my mental energy is not a good thing. Adjusting the position control was also much more perceptible when using the speakers in near field, and with the control at this setting, it made the speakers even less fatiguing.

As far as the "missing" bass was concerned, it wasn't all that bothersome. I'm accustomed to working with studio monitors where the bass is low in level. But it has to be of high quality to judge the sound of the instruments with low frequency energy, and the A-20s let me hear this. I never had a problem with overcompensation. I also never had a problem with a boomy midbass, and I had no need to ever set the boundary controls to attenuate the low frequencies. This is because the walls of my basement are a fairly far distance from the console and the speakers. When adjusted, they worked at attenuating the bass as advertised, so I guess this would come in handy if used in a smaller studio. I apologize for not giving these settings a real-world try, but there were no opportunities to do so.

After I was finished with the audition, I went back to the PSBs. I prefer them to the A-20 system. They combine the sound of speakers in a good home system, but also have many of the same qualities that make for a good studio monitor. There is a level of refinement in their sound that is not present in the NHTPros. The PSBs' images were larger, the low frequencies had more power, and the sound overall was more natural sounding. Some may complain that the PSBs sound is a little rolled off, but I don't find that to be a problem. However, if I were totally limited to near-field listening, I'd be perfectly happy using the NHTPro system. For my purposes where I'm not constantly using the monitors for near field listening, I'd rather use the PSBs.

Next up was to try out the A-20s in a professional studio. The studio I brought them to is not quite state-of-the-art, but pretty darn close. It has a mountain of equipment, but the whole shebang is centered around Studer and Sony 24-track tape decks (that can be linked for 48 tracks) hooked up to a Solid State Logic (SSL) mixing console that costs as much as a nice suburban home. They have many monitor speakers, but most of time they use Event 20/20bas or Genelec 1037Bs, both self-powered two-way models. I was there for a few sessions, and I also left them for a while for the studio operators to try them out on their own.

First we tried them against the Events, and the A-20s blew them away. The Events have a street price of about $800 (they list for $999), so one may think this is an unfair comparison. However, it really isn't, because the Events are extremely popular. They are used in so many studios these days, and I think that most engineers would be surprised that they could be surpassed in sound quality by so much. The chief engineer at the studio said next to the NHTPros, the Events sounded like "cardboard." But after using the A-20 system for an extended session he also commented that he thought the A-20s had a slight dip in the response in the lower midrange region. I didn't really hear this during my auditions, but I trust his opinion. But he also had lots of nice things to say about them, including the fact that they played very loud without breaking up -- he had the on-board dB meter reading more than 100 dB without worrying whether the speakers were going to give out.

We also compared the A-20s to the $4,000 a pair Genelecs. I thought the A-20 system fared extremely well, but I think the Genelecs are better in some important areas. The Genelecs have a "bigger" sound -- their image size is much larger and they are considerably more extended in the bass. This makes some sense, since the Genelecs have larger cabinets with larger drivers than the A-20s. But I've used the Genelecs many times, mostly in mastering sessions, and I often have problems getting used to the tweeters. I think their sound is rather harsh and can be fatiguing.

The studio engineer agreed that the NHTPros would probably be better at mixing music that contained acoustic instruments, but would much rather use the Genelecs for rock and R&B, the style of the majority of the studio's clients. Still, the A-20 system held its own, and it might be more of a matter of preference than anything else.

So there you have it. The NHT Pro A-20 Studio Reference Monitor System would be at home in any semi-professional or professional recording studio, and I think that they are worth the asking price. They are in my opinion better than what many recording studios are utilizing for small monitors these days, and I wish more high-end companies would get into the business of making professional monitors.

Using the A-20 system in one's hi-fi setup isn't as good of an idea. They aren't meant to be used for that purpose and my experience with them bears that out. If one insists on using pro monitors, the only model I've heard that sounds even halfway decent is the discontinued 4312 from JBL. They can be found second-hand for well under $1,000 a pair. But they couldn't be considered "audiophile quality" by any stretch of the imagination. I think buying a small pair of affordable speakers from a reputable high-end manufacturer, including NHT, will yield much better results for most home environments, but for the home or professional studio, the A-20s are an excellent choice. -TL