Product Review -
Kit Number 1 - October, 1996
By John E. Johnson, Jr.
|633 Granite Court; Pickering, Ontario L1W 3K1 · Canada|
|Phone 905-831-6555; Fax 905-837-6357|
|Weltronics Corporation, P.O. Box 80584|
|San Marino, California 91108|
|Phone 818-799-6396; Fax 818-799-6541|
|KEF Electronics of America, 89 Doug Brown Way|
|Holliston, Massachusetts 01746|
|Phone 508-429-3600; Fax 508-429-3699|
NAD 412 AM/FM Tuner; Input sensitivity 37
dBf; Capture ratio 1.6 dB; I.F. rejection 90 dB; THD 0.3%; S/N 74
dB; Output impedance 600 Ohms; Size 3 1/4"H x 17"W x
11"D; Weight 9 pounds; $299
NAD 613 Cassette Tape Deck; Frequency response 30 Hz - 18 kHz plus or minus 3 dB; Wow and flutter 0.1% DIN wtd. peak, 0.07% JIS wtd. rms; THD 1.0%; S/N 58 dB (Dolby NR off); Dolby B, C, HX Pro; Size 5"H x 17"W x 11"D; Weight 11 pounds; $349
AMC-CD8 Compact Disc Player; DAC: 1 bit MASH, 18 bit resolution, 32 x oversampling; Analog filter 5 pole; Frequency response 5 Hz - 20 kHz plus 0, minus 0.5dB; S/N 107 dB; Channel separation 90 dB; Output impedance 80 Ohms; Output level 2 Vrms; Remote control; Outputs one pair analog RCA, one digital RCA; Size 3 1/4"H x 17"W x 11"d; Weight 9 pounds; $299
KEF Coda 8 Speakers; Two way ported; One 1" soft dome tweeter, one 6 1/2" doped cone mid/bass driver; Frequency response 45 Hz - 20 kHz plus or minus 3 dB; Crossover frequency 3.5 kHz; Sensitivity 91 dB/w/m; Power handling 10w - 100w per channel; Size 13"H x 8"W x 11 1/2"D; Weight 6 1/2 pounds each; $300/pair - black vinyl finish
This is the first in our series of Kit Reviews, as per our readers' requests. As often as we can, we will publish reviews of complete "Turn key" systems at various price and performance levels. Some will be audio-only, as this one is, and others will be home theater. So, let's get on with it.
The present system could be defined as a mini, because of its compact size in total (see photo). It is not as mini as the ones you see in the electronic supermarket chains, but oh what a difference in the sound. The (essentially) one piece mini systems one finds elsewhere for $300 - $700 have more features than one can count (almost), but we think they sound a bit metallic, sort of like a super boom box. The NAD/AMC/KEF package we put together has separate power supplies for each of the components (toroidal transformers), remote control for one of the components (CD player), but not nearly as many features as the one piece minis. The question is, what are you looking for in a mini? To me, sound quality is utmost. To heck with features if they are at the expense of the sound. So, we put together a "mini" that sounds great at reasonable cost ($1500). If we added a larger amp and speakers, one could classify this as a full sized system, so "mini" is really semantics. The speaker size and amplifier power, to us, make this an official mini.
The NAD 310 amplifier is probably the most shocking component in this package in terms of what you get for the money. It is rated at 20 watts rms/ch into 8 Ohms, but the power supply is designed to deliver higher current, meaning that it will work with low impedance loads. It has a toroidal transformer, is solidly built, and supposed to be capable of delivering 20 amps peak (actual current flow is determined by Ohm's law: Current = Voltage/Resistance). There is a small, but noticeable turn-on thump. Circuits that eliminate such thumps cost money, and NAD has opted to keep the price way, way down. Each channel of the output stage combines an N-MOSFET with a bipolar transistor . . . very unusual. There are no triple emitter followers, which, again, keeps the cost down. Local negative feedback around the output transistors, together with output capacitors, keep the amp stable and free of DC offset. Essentially the 310 is a dual mono design. All the inputs are line-level (Video, Aux, Tuner, CD, Tape Loop, and Portable CD). The Portable CD input, on the front, allows you to connect your walkaround CD player (or portable tape cassette player for that matter). Tone controls for treble and bass can be defeated (bypassed), for those of you who are purists. The KEF Coda 8s have received worldwide acclaim, and they are 6 Ohm nominal. So, the 310 is just right for these speakers. Indeed, we were able to get well over 90 dB with this speaker and amplifier combination, with the sound being very clean and not boomy. The KEFs have the woofer at the top and the tweeter at the bottom. They know that these speakers will be on shelves, and woofers close to other surfaces can result in bass loading. They are also ported at the front, another feature that is handy when they are probably going to end up very close to the wall. We would also recommend using felt pads underneath the speakers to reduce vibration transfer between the shelf and the enclosures. The back of the speakers have binding posts, and we recommend that you use higher grade (but entry level) cables for this one connection, such as Nordost Flatline 2-Flat or their new cable Octava. The RCA interconnects that come with the various components are OK with this system (I never thought I would hear myself say this). Save your high-end interconnect money for component upgrades down the road.
The NAD 412 FM/AM tuner that we put with this kit is really nice. Plain, and simple, but nice. None of the major FM stations that we listen to had any extra sibilance, indicating that it is very sensitive and locks right on. A "Blend" switch allows tuning in to weaker stations, and reducing the stereo separation, but not eliminating it. A "Mono" switch is used for the really weak stations. The "Mode" button switches between "Tune", "Preset", and "Search". Tune allows manual tuning of stations down to hundredths of a MHz (this is unusual), for example, 106.02. There are 12 presets for FM and 12 for AM. A "Lock" button fine tunes the station to the strongest region. The station indicator is LCD, illuminated from behind, and easy to read in the dark. The back panel has good connections for the antennae, RCA jack outputs, and RCA input/output for linking with other NAD components. (A new NAD product, the NAD 710, available in December, 1996, will have the 310 and 412 combined into one package, for $299.)
Even if you don't purchase pre-recorded cassette tapes, no system would be complete without a cassette recorder/player, since we all like to have copies of our favorite CD tracks to listen to in the car. The NAD 613 Cassette Deck fills the bill here. The front load open/close operation is very smooth, and all readouts, including the tape counter, are electronic (rather than a mechanical counter). The back panel has two RCA input and two RCA output jacks, along with an in/out NAD link. Recording/playback is calibrated in 2 dB steps from -10 dB through 0 dB, up to +8 dB. Dolby B and C Noise Reduction (NR) are included, along with Dolby HX Pro. Dolby Noise Reduction (TM) works by increasing the recording level of quiet high frequency portions of the signal. Then during playback, the reverse occurs, reducing audible tape hiss. Dolby B reduces noise by 10 dB and C by 20 dB. The newest NR is Dolby S, which reduces noise in the lower frequency bands as well, but S is not included on this deck. To use B or C NR, the Dolby NR button on the front panel is pressed, selecting the choice. The same NR scheme should be used for recording and playback of any one tape (most likely B if the tape is for the car). What I really like though, is the HX Pro. It uses a self regulating bias which allows recording at higher levels than would be possible otherwise. It is always in the circuit and cannot be turned off, but there is no need to turn it off. We set the recording level such that peaks occurred at +2 to +4 dB rather than 0 dB, and it really works! With this setting, the music bounces around -4 dB to 0 dB, with occasional peaks at +2 dB, and occasional lulls at - 10 dB. In a way, this reduces hiss as well, because the playback level on the amplifier can be turned down. Bias is a high frequency tone that is recorded onto the tape along with the music (in the case of the 613, it is 107 kHz). Bias is necessary for tape recording to work. However, when strong high frequencies are present in the music, they act as bias in themselves, and along with the recorder's own bias, can overbias the tape. The HX Pro circuit senses the amount of bias and regulates it according to the high frequency content of the music, thereby allowing higher recording levels to be set. There is also a manual bias control, which allows the user to vary bias according to personal preferences. With decreasing bias, the high frequency response is extended, but the maximum recording level is reduced accordingly. If you start from a typical bias point and decrease bias, the high frequency sensitivity is increased, and thus high frequency response is extended. The maximum recording level will be reduced because the tape will become underbiased, rather than because the bias is contributing to tape saturation (overbiasing). Practically speaking, the increase in distortion will limit the level that anyone would want to record at. So, the amount of bias applied balances the frequency response with recording level capability. "High Bias" blank tapes are made of magnetic materials that will allow high amounts of bias to be applied, yet still providing an extended frequency response and high recording levels. Obviously, they are the more expensive blank tapes. A "Play Trim" control on the NAD 613 is used to adjust playback of tapes that are old or otherwise improperly biased. This deck has a lot of features, except for microphone inputs (most decks these days don't have any), and is very easy to listen to (it has a headphone jack for privacy). In fact, I liked it without any Dolby NR, and just set the recording level a little higher than usual (with older decks, the setting would have to be peaked at 0 dB, which is the approximate maximum recording level without significant distortion).
The system is rounded out with an AMC Weltronics CD-8 Compact Disc Player. It has a front loading single CD transport mechanism, with front panel function buttons for open/close, play, pause, stop, program, repeat, time, track, and search. It is very simple to operate, like the NAD components in this kit. The remote control is also quite easy to use. This is one of the reasons we included the CD-8 here (easy to use). It is not an extraordinary unit, just a good solid one. There is a digital coax output on the back, along with the standard analog RCA output jacks, if you should decide to upgrade later. We tried this out with an excellent outboard DAC, and the sound was improved considerably (also meaning that the transport section is a good one). But for a min-system, the inboard DAC is just fine.
In summary, if you are considering a mini-system for yourself, or for your dormitory-bound college kids, this is a much better one than you will find in the all-in-one-piece minis. Granted, they do have loads of cute features (and cost less), but in the final analysis, it is always how it sounds, not how many different colors and readouts that shine from across the room. You won't find an all-in-one that sounds like this kit. The components are all good enough that upgrades can be made later, such as a more powerful amp, outboard DAC, and so on . . . an idea that those college kids might let you know about at graduation time.
John E. Johnson, Jr.
© Copyright 1995, 1996, 1997 Secrets of Home Theater & High Fidelity
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