NAD In-Depth Review of C420 Stereo Amplifier Performance and Features

■CRITIQUE−NAD C 420, PARASOUND TDQ-150, AND ADCOM GFT-555II

■By Nancy and Duncan MacArthur

Some years ago we moved toward a minimalist audio system: one source, one volume control, one amplifi- er, and one set of speakers. In the process we elimi- nated much equipment, including our old Dynaco FM-5 tuner.

In the intervening years we forgot how much fun playing with a tuner could be. After burning in the NAD C 420, the Parasound TDQ-150, and the ADCOM GFT- 555II, we spent hours flipping through the FM band, finding a huge variety of music—some pieces famil- iar, some not. We ran across Navajo chants, opera, rock, symphonies, and Spanish music, not to mention the local deejay who termed himself the “Commissar of Your Radio Commune.”

Eventually the situation got out of hand. When the public radio station ran a long program of Colombian music, I found myself dancing around the living room to the Swamp Cumbia. Halfway through the song, I turned and ran smack into a scandalized eleven-year-old.

“Cut it out, Mom,” he growled. “Whatever for?” I asked.

He considered the matter briefly. “’Cause if you don’t, I’m gonna get out the video camera and put you on the Internet.”

Oh. Perhaps it was time to stop dancing and start writing this review.

REVIEWING TUNERS

An FM tuner review requires a different listening ap- proach from reviews of other components. Local FM stations rarely provide a clean, uncompressed sig- nal. Even if their signal quality is good, they typically don’t play the same piece repeatedly for the conve- nience of reviewers. Obviously, under these circum- stances a listening critique of tuners can’t be as rig- orous as critiques of other components. But at least three aspects of tuner performance beyond lab test results have some importance.

First, listening tests may reveal some sonic differ- ences. If the tuners all sound the same, we’ll say so; when we hear obvious differences, we’ll point them out. Second, if the sonic signatures are similar, the choice may devolve upon price, features, and opera- tional convenience. Third, a brief comparison between these tuners and other sources may be useful. Our goal is to give you an idea of what to expect before making a purchase.

The NAD C 420 and the Parasound TDQ-150 arrived from the manufacturers by way of Chuck Hansen’s lab. The ADCOM GFT-555II was an older model borrowed from Ed Dell for use as a baseline.

We burned in each tuner with an antenna signal sufficient to exceed its muting threshold for at least 100 hours. Tuners are significantly easier to burn in than many other components because they do not have moving parts or large sources of heat. The sound of the NAD and Parasound changed significantly over the burn-in period. (Presumably the ADCOM had burned in long ago.)

Following burn-in, we listened to each tuner in turns using the same set of popular and classical stations. As might be anticipated, the popular stations provided a horribly compressed signal. (On the other hand, they frequently played songs we knew well.) The rest of the

reproduction system was identical in each case, and all three tuners were plugged into the same circuit of a Monster Cable HTS 2000 power conditioner.

Each tuner also receives the AM band, although we concentrated on FM performance in this review.

ANTENNAS

The reception quality of any tuner critically depends on the antenna connected to it. For all our serious listening we used a multi-element roof-mounted Radio Shack special.

Out of curiosity we briefly connected the twin lead dipoles supplied in each box to their respective tuners. Because most of the stations we listen to are about a hundred miles away, we didn’t anticipate satisfactory performance from the dipoles. Table 1 lists the number of stations in our area that each tuner received cleanly. When we say cleanly, we mean with lack of noise and sibilant distortion. (Many more stations were intelligi- ble from a DXer’s standpoint.)

Practically speaking, all these sensitivities were comparable except for the NAD’s reception with the in- door dipole. All three tuners exhibited good sensitivity when attached to a “real” antenna.

Even if your system hasn’t suffered from them be- fore, the introduction of an external antenna that is grounded for safety reasons often causes a ground loop. The antenna safety ground is likely to be located far from the audio system ground and may easily be at a different potential. These problems may be exacer- bated by a grounded tuner (such as the Parasound) but can be present even if the tuner itself is unground- ed. Numerous companies, including Jensen, Mondial, Tributaries, and MIT, manufacture products intended to break these ground loops.

APPEARANCE

The NAD C 420 is a rarity among components: a good-looking black box, well proportioned with an el- egant oval display window. Its preset/tune rocker echoes the shape of its display window. The most salient feature of the Parasound’s appearance is its tiny size—roughly half as wide, half as high, half as deep as the other tuners. (If you have a 17″ rack, you could mount the Parasound side-by-side with its matching preamplifier.) The ADCOM GFT-555II is a standard chunky black box; its most noticeable fea- ture is a long row of buttons on the front panel.

Popping open the Parasound reveals a single, densely packed, PC board. The board dominates the in- terior of the Parasound and fills the available space. Although the Parasound is much smaller than the other tuners, it weighs about the same.

The NAD’s main PC board is well laid out and less densely packed. It fills about half the enclosure. As you might expect in an older component, the ADCOM’s main board nearly fills its box. Although all three tuners are well laid out and cleanly constructed, the NAD and ADCOM probably would be easier to service or modify due to the extra “elbow room” within the enclosure.

EASE OF USE

Both the Parasound TDQ-150 and the ADCOM GFT- 555II were easy to use. The Parasound has five front- panel buttons and includes a remote. To set the pre- sets you must use the remote. (You can tune the pre-

sets sequentially using buttons on the front panel). The remote is also handy for changing stations and ac- cessing the presets in random order; in addition, it has preamplifier controls intended for use with a matching preamplifier (also half rack width). The Parasound uses the U.S. frequency interval of 0.2MHz and can be tuned rapidly across the FM band.

The 30 presets on this tuner are accessible in se- quence by the up-and-down buttons on the front panel. We preferred the random access ability provided by the remote. The tuning buttons on the Parasound operate in two modes. A short press on one of the tun- ing buttons will change the frequency by 0.2MHz. Ac- cording to the manual a continuous press will tune to the next strong station; however, our sample would not stop at any station regardless of strength. Like the En- ergizer Bunny®, it kept going and going and going.

The ADCOM GFT-555II has only 16 presets (8 AM and 8 FM) but has an individual front-panel button permanently assigned to each. It thus provides totally random access for setting and tuning the preset fre- quencies. The ADCOM didn’t come with a remote, and its manual makes no mention of remote capability. It tunes in 0.1MHz intervals.

The ADCOM has three modes of tuning. A short press on one of the tuning buttons will change the fre- quency by 0.1MHz, and a continuous press will tune continuously. Activating the “FM scan” switch will stop the tuning at the next strong station. These features are straightforward and easily understood; describing them here takes more time than learning to use them.

The NAD C 420 also features 30 presets that are ac- cessible sequentially from the front panel. A remote control is optional with the NAD: it’s the same remote supplied with the matching NAD preamp, and the manufacturer doesn’t want to charge you twice. If you buy the tuner but not the preamp, we would strongly recommend purchasing the remote separately.

Many of the NAD’s features were not self-explanato- ry: we frequently had to refer to the manual. The tech- nique for erasing presets, which required multiple timed pushes of two buttons, seemed particularly opaque.

Different buttons operated in different ways. Some toggled front-panel lights, and some didn’t. We had to push some for a certain number of seconds to enable one feature and a different number of seconds to en- able another.

The NAD uses a seek mode of tuning: it stops at every strong station whether you want it to or not. This characteristic becomes less important once the pre- sets are set but can lengthen the process of moving from one end of the band to the other.

This tuner also incorporates RDS, a useful feature if nearby stations transmit RDS information and if the

TABLE 1

NUMBER OF STATIONS RECEIVED

CLEANLY FOR EACH TUNER/ANTENNA

COMBINATION.

	OUTDOOR	INDOOR
	ANTENNA	DIPOLE
NAD C 420	25	19
Parasound TDQ-150	29	26
ADCOM GFT-555II	27	25

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