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Today's receivers come loaded with extras - By THOM PRINGLE - Off Duty / Europe / November 1973
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AS THE MAN OF THE HOUSE and the resident (audio club) card-carrying hi-fi nut, your problems are probably, (1) you can't persuade your wife to enjoy your hobby because she's afraid to touch the equipment and (2) you can't keep your kids away from the controls. Your problems are about to get bigger.

When you start eyeballing the new receivers, tuners and amplifiers this year, don't be surprised if you find one that starts staring back at you. The new units are alive with gadgets - everything from heat sinks to kitchen sinks - and there are enough knobs, dials and meters on the front to keep you spinning and twirling happily for months. Your wife will most likely file for a divorce and kids will follow you down the street like the Pied Piper when you haul that monster home. Your only hope is to convince the little woman she can use the new receiver to place toll-free calls to her mother in the States. Tell the kids it's programmed to play only Lawrence Welk music.

All the major manufacturers are elbowing and kicking shins to see who can bring out the newest 4-channel receivers - and this year they're dead serious about it. There is still a variety of 4-channel methods, so the new units contain circuitry for all the methods which means that there are a lot of controls and switches, of course. With four channels come four sets of controls, (often) four VU meters and so on. Should you have a super system, with separate components and high-power amplifiers, you might want to consider leasing a larger house before going 4-channel.

Actually, it's not really as bad as we've made it sound and, of course, it's great fun for the confirmed audio-phile. Now, too, that European manufacturers have embraced 4-channel, you can expect rapid strides to be made in producing software, resulting in some fantastic recordings and great sounds in your living room. Some of the newly introduced units have, though, become formidable in their complexity because manufacturers are trying to include all the latest developments into a single unit.

4-channel remains the biggest news in audio today and there are still three major methods of squeezing four channels into a single groove on a disc, Regular Matrix (Sansui's QS), SQ matrix and CD-4 (modulated carrier).

Many manufacturers have included circuitry in their latest units to handle all of these systems or they have included provisions for add-on units, of which there is a wide variety.

Thus, in the higher-priced, all-in-one units, dozens of input and output connections are required to handle the multiple 4-channel speaker systems, 4-channel tape decks, remote balance controls and regular stereo connections.

At the same time, dynamic noise reduction is also being considered by some manufacturers who are either building the circuitry (such as Dolby B-type) into their receivers or including the control circuitry for an add-on unit. To accomplish either requires more controls and connectors, again adding to the complexity of the overall unit.

New trends in circuit design contribute to the confusion, too, by requiring extra switches and connections so that the new "strapple" 4-channel amplifiers can be converted to higher-power stereo amps when 4-channel operation is not desired. This feature offers improved efficiency but it's a feature which, most likely, only avid hi-fi fans will appreciate. Such, too, is the case with some of the new circuit design improvements.

What do all the strange letters stand for?

You may read that an amplifier is an SEPP-ITL-ICL-OTL-OCL- type (single-ended, push-pull, input-transformerless, input-capacitorless, output-transformerless, output-capacitorless) but what does it mean to you?

Relatively little. For the industry in general it means that units are now being manufactured to higher standards with fewer components and, thus, less expensively. You save money. The reduction in reactive components (capacitors and transformers) will change the phase characteristics of an amplifier but this is something you won't notice - your amplifier probably already exceeds the capabilities of your speaker system.
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While quadraphonic sound will see a lot of future change, it has firmed up a great deal in the last year. Here are some of the things you will note when looking through the units available.

For simplicity, we have labeled two types of matrix decoders, Regular and SQ. There are definite differences between the two and you should really have the same type decoder as the material you are trying to decode. There are also a few "universal" decoders which claim to decode any type of material.

Some units may have one type or the other decoder with connections for add-on adapters and some may also have decoder with logic circuitry to enhance separation. With the various adapters available today, however, you can easily add any type decoder system you want with no difficultly.
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JVC's CD-4 system which uses a carrier has been included in several units along with built-in matrix decoders. Other manufacturers have provided pockets in the side or bottom of their units which accept a plug-in CD-4 module, while still other units have external connectors for add-on demodulators. As is the case with matrix systems, CD-4 can be added to almost any system without difficultly.
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These are the 4-channel matrix decoders that are tacked on the output of a stereo amplifier and produce 4-channels at high power levels. Therefore, you will see several units in our SHOPPER which have only two amplifier channels yet claim to produce genuine 4-channel sound - they do. And effectively, too.

But be careful to see that the unit you are considering actually has the decoder and is not offering simply four speakers connected in two stereo pairs. Remember, too, that stereo amplifiers with high-level decoders cannot handle discrete 4-channel material as can units with 4-channel amplifiers.
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Most of the 4-channel units in our listings have four separate amplifier channels and are marked as such. This means that they can handle either discrete 4-channel material or decoded matrix material.
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Several units in our listings have circuits which can enhance stereo material by feeding portions of the material to the rear speakers thereby giving a 4-channel effect. This may be accomplished with a delay circuit, by separating out-of-phase signals for the rear channels or by frequency differentiation. In any case, remember that this is not matrix nor discrete 4-channel, but simulated 4-channel.
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These are jacks located on the back panel of the tuner or receiver which will accommodate an external device to decode 4-channel broadcasts whenever a final system is agreed upon. This is a bit of insurance since it is possible that stations may simply use a matrix system which can be decoded with your built-in matrix decoder.
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The most complete specifications for amplifier outputs shows the RMS power when the amplifier is driven into an 8 ohm load with all channels operating without exceeding a given amount of distortion at any or all audio frequencies.

Some amplifiers will be rated with only one channel operating which generally means that they can produce more power, as is the case when the amplifier is rated only at a midrange frequency. A full-frequency, full-operation specification might read, "RMS power output 33 watts per channel into 8 ohms at all frequencies with 0.5 per cent harmonic distortion, both channels operating."

This description covers just about all the variables (with the exception of line voltage) and is an excellent start toward choosing an amplifier. You will note that many units omit one or more of the factors in the preceding description and, while this does not mean that the unit is inferior, you might want to take a more conservative view of the specifications given for the unit.
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A good amplifier covers the audio spectrum with a minimum of variation. In other words, at a given amount of power it should amplify all frequencies equally-within one or two decibels (±1 dB). Frequency response is usually measured at normal listening levels, which under average conditions is about one or two watts. At higher power levels, a really "flat" response is more difficult to achieve and such an amplifier is likely to cost more. Here again is where the full-frequency power rating is important.
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This measure follows standards set up by the Institute of High Fidelity (IHF). It represents the range of frequencies over which the amplifier can deliver at least 50 per cent of its rated power.

"Half power," incidentally, is a reduction of just 3 dB with sharp peaks at some frequencies and dips in the response curve at another frequencies. So the amplifier's power bandwidth of, say, 20-30,000 Hz, and its low-level frequency response curve (ideally, within 2 dB throughout the audible range) are tell-tale indicators as to its performance.
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The distortion figures tell whether an amplifier does anything to the signal other than amplify it. Usually, both "total harmonic distortion" (THD) and intermodulation (IM) distortion are given.

Figures lower than one per cent are considered acceptable. For a truly meaningful rating, look for harmonic distortion measurements at more than one frequency. Like the power rating, the spec is likely to be more impressive at a mid-frequency than at the extremes of the audio spectrum.
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All amplifiers add signals of their own to your input signal. You can hear this by turning up the volume control on your amplifier without putting any signal into it. The hum and noise specification tells you how much extraneous sound the amplifier produces in relation to the output signal.

Look for a rating of at least -60 dB and an even better -70 dB rating if you plan to do a lot of tape recording. Make sure that the rating is taken through the phono input and therefore includes the preamp (where most of the noise is added).

The Tuner Specs are no more so interesting, so we skip them.
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With the more complete specifications it is easier than ever to see what your money is buying. One thing, however, which you can't tell unless you're a trained technician is the amount of longevity built into a unit through careful design and high quality.

About all you can do is rely on the manufacturer's reputation, the advice of a trusted technician and, perhaps, independent test reports. In most cases, you'll find that those units recommended for long-term quality are also the more expensive units - so, you're trading dollars for longevity.
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Each manufacturer has some unique features and this is one of the interesting parts of comparing various units.

• How many sets of speakers do you want to operate?
• Do you want remote control?
• How many tape decks do you want to connect?

The questions and options seem endless. These are the features, though, that allow you to build into your system the versatility and individuality you want. And with the wide range of units available in this SHOPPER, that means you can have just about anything.
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