The Aiwa AD6800 stereo cassette deck has recently appeared as a 'top of the range' machine from this manufacturer, who has been building up a fine reputation in the highly competitive domestic and 'semi-professional' cassette deck market. Available from certain discount warehouses and friendly local Hi-Fi specialists (yes, there are such anachronisms, and happily they seem to be on the increase in the UK), the AD6800 has a lot to offer, and should certainly be considered by those requiring high quality cassette facilities at a realistic price.

The purpose of this article is not to take the AD6800 apart in the manner of a technical review; that will no doubt be undertaken elsewhere in print by persons more qualified than the writer (like, my Avo with a bent needle isn't up to much). Instead, I intend to give an account of using the machine in a semi-pro environment and to describe its benefits and shortcomings in the light of everyday use; after all, the machine was presumably designed for the 'enthusiast' who aspires to high quality sound from the cassette format in such an environment where the lofty heights of Nakamichi and top-flight Technics could not be justified (to spouse and bank manager particularly).

The AD6800 under review was purchased some three months ago to upgrade the cassette department of my domestic system, which since 1970 had consisted of a Sony TC160 coupled to a separate Dolby B processor. The AD6800 was substituted in the space on the shelf vacated by the Sony, and coupled into the rest of the system, the relevant bits and pieces being — Disc facility: Thorens TD126/SME 300911 (improved), fitted with Fluid Damper/Ortofon M15E Super. Amplifier: Quad 33/405 plus an additional Quad 33/303 combination with Integrex NRDC-Ambisonic decoder for when I feel in the mood for being submerged in all the surround-sound matrices known to modern Man. Speakers: Mission 730, coupled to the 405 using SHF speaker cable, 'Rear' speakers are a pair of B&W DM3s coupled with 6-amp cable (I'm still saving for another two coils of SHF). Additional sources: A couple of Revox A77 MkIVs, 7½/15 in/s, plus a cupboard full of studio-recorded material reduced to ½-track stereo for home consumption. Finally, perhaps because I don't take radio seriously in this country, VHF/FM facilities in the way of a humble Armstrong 624 tuner, fed from a J-Beam SBM4 Stereobeam antenna mounted 60 feet above ground level.

I'm glad to say that the AD6800 has lived very happily wedged in amongst that little lot, not being at all over-awed and giving an excellent account of itself.

Installation and setting up should present no problems. Designed as a vertical front-loader, it is capable of being stacked without apparent hum-field problems or ventilation difficulties. It is, however, quite bulky and relatively heavy, being approximately 18in W x 6¼in H x 12in D, weight around 22lb. Electrically, the machine is built to 'Class II standard' as we British would have it, being double-insulated and fitted with a two-core mains lead. Hum-loops are therefore unlikely, and a ground terminal is provided on the rear panel should hum present a problem to the user.

Patching into an audio system should present no real problem either. Phono sockets are provided on the rear panel for 'Line' in and out connections, together with a 5-pin 180° DIN socket, duplicated on the front panel and disconnecting the rear panel DIN socket when used. Despite my dislike of the DIN system (current sources?) I have found this socket to be useful on occasions. The front panel also carries two ¼in 2-pole jack sockets for unbalanced microphones (unlikely to be used by the likes of us) and a ¼in 3-pole jack socket suitable for 8 through 600-ohm headphones. This socket did not provide sufficient drive for a satisfactory SPL in any of the cans I've tried, from cheap and nasty unmentionables to names I dare mention, Koss K135, PRO 4AA and AKG K240. But to be fair, this fault, if fault it be, is certainly not unique to Aiwa. Finally, a 2.5mm miniature jack socket on the rear panel provides for remote start/stop in the record mode, and is intended to be linked to record decks offering a 'sync' facility, starting the tape moving as the stylus is lowered onto the disc — neat but naughty!

The output level of the Line out sockets is adjustable for each channel by a concentric pot on the front panel, which also controls the level at the headphone socket. The output of the DIN sockets can also be varied with this control, or fixed at 'Line' level (0.775V corresponding to 0dB VU) irrespective of the control setting. Thin but strong fingernails or a small screwdriver will be found useful in operating the slide-switch involved. Electrical matching with 'domestic' audio equipment shouldn't present any difficulties, all inputs and outputs falling within the present norm in respect of signal levels and impedance.

Mechanical controls are piano-key type, smooth and positive in use, but I wish the stop/eject key had been made the widest, instead of the forward key, which is centrally placed in the row. Somehow, I just keep hitting the forward key when attempting to stop the transport in the winding function. The fast forward and rewind keys can be operated in conjunction with the forward key to provide the now trendy 'cue and review' facility, where the tape is brought into contact with the head at winding speed. Useful to some I suppose, and at least the HF is muted to prevent screeches, but I found the facility a sure recipe for stepping the tape pancake inside the cassette housing. Over-enthusiastic use will certainly cause the pancake to jam, usually by binding to the foils. I stepped a brand new TDK SA C60 so badly after a few 'reviews' that the deck could not transport the tape at the correct or constant speed. Obviously, a stepped cassette usually responds to a sharp rap face down on a flat surface and then being wound through from end to end to even out the steps or ridges in the tape pancake which are binding to the foils, but this is irritating to the user! So I advise you to go easy on this facility if you must use it. The pause control is positive, allowing instant starts and click-free drop-ins, so dub-editing is possible if you want to try it.

The door to the cassette compartment flips up into the machine, and loading the cassette into the maw of the beast is an experience unnerving to the newcomer. Depressing the stop key past the halfway position operates the eject mechanism, opening the door and bringing the cassette carrier into position. Inserting a cassette into the carrier activates a small motor which drives the carrier back and down into the interior, dropping over the spindles and aligning the cassette correctly. Despite the grinding and growling noise which accompanies this operation, I've yet to lose a finger! The cassette is very firmly held in the carrier, allowing very little free movement (full marks) but since it is loaded into the carrier face out, invites contamination of the precious oxide by sweaty fingers (not so full marks).

Despite the legend on the door panel, the AD6800 is not what we would expect a '3-head' machine to be. The third head is only a test head concerned with the bias-setting procedure. The AD6800 has a conventional record/replay head, this being a ferrite guard type. Nor does the 'Azimuth Adjust' slider inside the cassette compartment on the head cover plate have anything to do with the main head azimuth. Once again, it is concerned with the bias-setting procedure and brings about a close encounter of the third head (sorry!) azimuth with that of the main head in order to satisfactorily reproduce a high-frequency tone — there is of course no pressure pad in the cassette at the insertion point of the test head, so the azimuth slider overcomes the worst of the mistracking and HF loss.

Bias and equalisation are selected using two chunky switches on the front panel, equalisation offering 70μS or 120μS options, and the bias switch three levels of bias. The machine can therefore handle pretty well any contemporary oxide formulation. The third switch of the array enables Dolby B circuitry, with the option of a 19KHz MPX filter if recording from FM stereo or CD4 sources; the fourth switch selects the source input (Mic or Line/DIN) and the special 'Test' position for correct biasing.

All three levels of bias can be varied from a nominal position by means of three small pots below the left channel level meter. The appropriate twiddler is lit by an integral LED according to the position of the bias switch, so you know which pot to adjust. This arrangement is very pretty, green, orange and red LEDs being used, and the whole biasing great fun and irresistible to the inveterate knob-twiddler and switch-clicker; select 'Test', disable Dolby, engage record mode and slide 'Azimuth Adjust' to obtain maximum deflection of the right channel meter. Now adjust the bias until meter indications are equal in both channels. Done!

Briefly, the 'Test' position enables an oscillator circuit, and test signals of 400Hz and 8KHz are applied to left and right channels respectively. After adjusting the test head to an optimum position to track the 8KHz tone, the bias is adjusted to produce a flat response, or so the theory goes. Aiwa call this 'Flat Response Tuning', but I'll leave it to the technical reviewers to see just how level the response can be 'tuned' in this manner. At a subjective level, it really does seem to work! The bias pots have a central detent, so if you tire of the 'tuning' hassle, or don't require the last drop of performance, an 'average' can be set instantly. Very usefully, the bias pots provide an overlapping range. It was found impossible to give BASF Ferro Super I sufficient bias on the Ferric bias range, but switching in FeCr bias range and retaining 120μS equalisation helped to 'tune' a flat response. Certainly, recordings did not suffer in any audible way.

The rotary record level control is concentric and is very smooth and easy to use. The level meters are a joy to the enthusiast and actually meaningful to the more professional user. Each meter has a conventional VU movement, calibrated from -20 to +5dB. A push-button enables a Peak Reading movement, mounted co-axially with the VU, but with a scale extending from -40dB to +10dB. This movement responds very well to transients: I judge its attack as faster than a PPM, but with a similar decay. Only the 0dB calibrations coincide on the separate VU and Peak scales and some practice is necessary to make sense of all the swinging needles. Usefully, the Peak Reading movement can be set to hold the reading of the highest level attained, and will retain this for about 30 minutes.

I didn't find this a particularly good feature, and would have preferred a much shorter hold time, say about 30 seconds. Since the meter responds faithfully to all kinds of transients, including disc impulse-noise and other odd switching clicks that may happen by, the overlong hold is rather a nuisance, since the meter could be more usefully employed reading actual music peaks which may not be so energetic and reach such levels. So my advice is to experiment thoroughly with bias-setting and making sense of the meters before using the AD6800 for a serious recording. It is vital that you know just how far you can push your favourite tape. Over-cautious observation of the meters can easily cause one to undermodulate certain tapes, especially superferrics, and lose out on the dynamic range of the machine. On the other hand, it is fairly easy to overmodulate FeCr and CrO₂ types at recording levels which superferrics take in their stride. So experiment beforehand to avoid disappointment.

Although the record mode is indicated by a red LED set between the meters, visible indication of Dolby status would have been appreciated. It's quite easy to flip the Dolby on, and forget that the first Dolby position on the selector also selects the 19kHz filter.

A tape run indicator is provided to further delight the enthusiast with its twinkle twinkle, but since it can be difficult to see the tape moving in the depths of the machine, this feature is useful and reassuring. The 3-digit tape counter has a memory facility linked to the autostop to enable rewinding to a preset 000 position. This can be a nuisance to simpletons like myself who have lived all these years without such refinements and get freaked-out when the stop suddenly and unexpectedly engages during winding, all because the memory button is accidentally engaged! Bearing in mind the retail price of the machine, I feel that a Dolby line-up facility and calibration presets could have been incorporated. After all, there is a 400Hz oscillator in the machine...

Access to the tape path for cleaning is easy once the technique of sliding off the head coverplate is mastered. For some time, I wondered about the purpose of the metal bar under the transport keys, and eventually found it very useful in this operation. The ham-fisted and sausage-fingered may find it very difficult to gain sufficient purchase on the coverplate in order to get it to slide back and away. Either use the forefingers to push the cover, and rest the thumbs on the bar, or rest all the fingers under the bar and push the cover with the thumbs. It works!

After all this waffle, how does the AD6800 come up to expectations? In my opinion, the machine gives as good as it gets, if properly set up on high quality tape and care is taken with recording levels. There are times when I find it difficult to believe that I am listening to a Compact Cassette. Obviously, listening hard and critically, one does notice imperfections, and it just will not stand direct comparison with a 15in/s open reel master, but it certainly gives a 7½in/s tape on a Revox A77 a run for its money, provided that the Aiwa is aided with Dolby. It comes in a valiant second, but is certainly not left out of sight.

Finally, the instruction book. This comes complete with a circuit diagram, and I found the book useful if rather brief. Mine was an English-only version, saving me the usual wading through multiple explanations in 52 languages to find the few lines on each page that could be understood. In addition, I could actually understand the instructions, which seem to be largely free of the weird phraseology and howlers so common in instructions originating from Japan and the Far East. The circuit diagram, however, is likely to induce blindness if you so much as try to follow a particular buss as it weaves in and out of the circuit blocks, rather like its red London namesake in heavy traffic. A brief poke inside the machine leaves me resolved to return the machine to the distributor should the need ever arise for servicing beyond the occasional tired fuse blowing and needing replacement. All the fuses are in a neat row and easy to get at. Possibly the official Service Manual does a better job of resolving schematic diagrams with the actual circuit boards and does not indulge in graphic mazes. I'm quite content to enjoy the machine in use as a high quality cassette deck, and I would stress the word enjoy. In three months, I've found the Aiwa AD6800 a joy to use and listen to, and now the honeymoon is over, I certainly think that I can live with it very happily for years to come.

rrp £369.60/$650.

Pete Carbines is the technical adviser to the audio buying department of a large High Street chain with a shop almost everywhere. He specialises in domestic snd semi-pro audio and TV systems evaluation.