I recently had the opportunity to check out the NHTPro (now called Vergence) A-20 monitoring system that Bruce Bartlett previously reviewed (PAR, 6/99, p. 22). I agreed with his findings and observations almost 100 percent but zeroed in on an obstacle that I find common in many loudspeakers today, namely metal dome tweeters. They just don’t sound right to me.
The A-20 system is indeed a terrific monitoring solution that does many things better than a great majority of monitors, powered or passive. But I still get hung up on metal domes. Sorry.
While cruising the Vergence Web site I came across the A-10 system, which looks remarkably like the A-20 with a lower powered amplifier, fewer features and, voilá – a soft fabric dome tweeter.
Like the A-20, the A-10 has an outboard-dedicated power amplifier with built-in boundary and position controls – or low and high frequency EQ if you like. The crossover is unique in that most of the low-frequency heavier crossover components are located in the external amplifier, while the smaller, lighter components are in the speaker enclosure where internal volume is at a premium with a speaker this size.
One interesting component of the crossover is the supplied 20′ cable between the amplifier and the speaker, where the resistance, inductance and capacitance of the cable are an integral part of the circuit. It is well known that speaker cable can affect the performance of a playback system, many times in a negative way.
In this design, the speaker cable is actually part of the crossover. This amplifier absolutely cannot be used with other speakers – one of the reasons why XLR connectors are used on both ends instead of normal speaker connectors. While normal microphone cables could work as extension cables in a pinch – with compromised performance – it is not recommended. The supplied cables are soft, flexible and of a heavier gauge than standard microphone cable and are not shielded.
The 2-RU high, 150-W/channel dual-mono amplifier is discrete and of bipolar design; op-amps are used for the active balanced inputs and EQ circuits. The input sensitivity control has five steps with 7 dB per step and a gain range of ö10 dB, -3 dB, +4 dB, +11 dB and mute. Both the low-frequency boundary control and the high-frequency position control only have two settings each, compared to the A-20’s five settings each. I personally don’t think the extra settings are necessary under normal conditions.
The A-10 amplifier can accept both balanced and unbalanced inputs on either XLR or 1/4″. A green LED indicates power on and a red LED indicates clipping. The rated peak acoustic output is 116 dB SPL (100 ms pink noise at 1M), which is only a dB lower than the A-20.
The two-way acoustic suspension enclosure is home to a long-throw 6.5″ treated paper cone woofer and a soft dome, liquid-cooled tweeter. The tweeter is very smooth and natural sounding with minimal coloration, making extended listening possible without fatigue.
Vergence believes in acoustic suspension designs for all its products and I couldn’t agree more. The bass on the A-10 system is smooth and tight with good pitch definition. Normally in a sealed box monitor of this size, the low end is weak and a bit wimpy. The A-10 amplifier has a frequency response tailored to the system so that in a room overall frequency response is fairly smooth from about 48 Hz out to 20 kHz. This proved to be the case in my room. The company was kind enough to send me the controlled amplifier response curves to show only a moderate amount of EQ is all that is necessary to get smooth response down into the 50 Hz region. Overall system THD is rated at an impressive specification of < 0.8 percent (90 dB SPL, 100 Hz to 10 kHz at 1M).
I wanted to see how well the A-10 integrated to a subwoofer so I tried the Hafler TRM-10, which has a single, long-throw 10″ driver in a vented enclosure. I set the low-pass crossover of the TRM-10 to 40 Hz and just let the A-10s roll off naturally without any high pass filtering. To my surprise, the integration was very smooth without that “Oh you have a subwoofer” feeling. Whether or not you need a sub is a matter of taste. In larger rooms with some kinds of music that bottom octave may be needed. Or you may want to crossover to a sub at a higher frequency and get more overall system headroom.
By the time you read this, Vergence will again have a stereo subwoofer system with an outboard-dedicated amplifier optimized to work with the A-10/A-20 systems. I’m now in the process of putting together a surround system with A-10 components and the new Vergence B-20 stereo subwoofer system – it should be killer; I’ll keep you posted.
The A-10 Studio Monitor System just might win the bang-for-the buck award for high-end close- and mid-field monitoring. At $1,250 retail, this system is a great bargain.
Contact: Vergence (formerly NHTPro) at 707-751-0270.