This relatively simple deck is a front-loader, enclosed in a metal cabinet; only two gain controls are provided on the front panel, one for each channel, and these are several cms apart, which makes it rather fiddly to adjust record level. Lever switches provide input switching, two positions each of bias and equalisation and Dolby switching. The record-level meters showed longer transients reasonably accurately, but short ones poorly, the meter response showing considerable LF and EHF loss, and there are no peak reading lights. The audio outputs are controlled by a ganged pre-set gain control on the back panel.
The microphone inputs (mono jacks on the front) did not mute the DIN socket, and were very insensitive, also having a somewhat poor clipping margin; the subjective quality was quite good, however, but just a little hissy.

 The DIN input had good sensitivity, and an adequate clipping margin; although slight noise degradation was noted, it was better than many. Some 3rd harmonic distortion was noted on this input at higher levels, but should not be too serious from a standard source. The line inputs were slightly less sensitive than average, but no clipping problems were encountered, and input noise was exceptionally quiet, which is most commendable. The mpx filter is permanently in, and showed a rather drastic cut at 15kHz, averaging -4.25dB.

The replay azimuth was considerably offset, and pre-recorded cassettes were distinctly muffled before adjustment. Replay hiss levels were slightly noisier than average on ferric, but chrome was average, Dolby also showing around 9.5dB improvement; hum measured at a very low level which is commendable. The replay amplifier clipping margin was very poor, occurring at +5.75dB and as expected replay amplifier distortion at high levels was much worse than average, but satisfactory at Dolby level. The ferric replay response showed a bass loss, but was well up at HF, with a +2dB average shelf being noted which clearly degraded hiss performance; the chromium HF response however was approximately correct. Headphones worked quite well, but clipping on high recorded level tapes was obvious, created by the replay amplifier problems.

Maxell UDXLI (Hitachi type) showed an excellent pen chart up to 13.5kHz with and without Dolby, but some bass woodles were noted. 333Hz distortion averaged .6% at Dolby level, but reached 4% on the left channel and 2.5% on the right at 4dB while overall noise was average with the usual Dolby improvement. Provided care was taken not to record levels which caused clipping on replay, the overall quality was excellent, with almost no HF compression at all, and a clear, open sound quality which shamed many a more expensive machine. UDXLII (also Hitachi) showed a noticeable HF loss, amounting to -2dB at 10kHz, which was exaggerated with Dolby. Distortion averaged 2% at Dolby level, but reached 8% on the left channel at +4dB and 5.6% on the right. Overall noise, however, was excellent, but with just 9.25dB Dolby improvement. Distortion was all too evident at low frequencies, but if the recording level is kept down it would be satisfactory. The tape was clearly under biased, and under equalised, and I assume poor quality control is responsible for this.

Wow and flutter measured reasonably well, and speed was quite accurate. HF stability was excellent, and erasure also most creditable. Crosstalk measured well, particularly at middle frequencies, but spooling was just a little slow at 2.4 minutes. Provided you can accept the very poor replay clipping margin, which will necessitate very careful adjustment of recording levels, this machine will give a very fine overall sound quality in the ferric position, though pseudo-chrome may not be so satisfactory. Surprisingly for a budget machine there were fewer problem areas than usual, and so the machine can be recommended with caution. However, a 'best buy' is withheld because of the replay clipping performance problem, though this may or may not be considered important. It should be noted that some pre-recorded musicassettes and tapes made on high quality machines may play back with some distortion on peaks.
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The D-850 is a 3-head deck allowing monitoring and having record and replay gaps in a combined head. The front-loading, metal-encased machine incorporates facilities for a Dolby tone oscillator to be used in conjunction with record cal. controls.

The meters are peak reading types, but these under-read transients slightly. Friction-locked record and replay rotary gain controls are provided, and levers operate Dolby in/out with FM Dolby and bias and equalisation separately (each with three positions), while push buttons operate A/B monitoring, input switching and Dolby tone oscillator functions.

The deck controls worked very well, the rec/pb head being engaged with a motor against the tape; loading is very simple and smooth. Phono line in/output sockets are provided on the rear and are complemented by a combined 5-pole DIN socket with an additional switchable one for monitoring, thus avoiding crosstalk.

Two mono jacks are supplied for microphones, the input sensitivity and clipping margin being rather poor. The DIN input had adequate sensitivity and the clipping margin was adequate, although not as good as usual, from a DIN source. However, virtually no noise degradation was noted from a standard DIN source, which worked well with no problems.

Whilst the line input sensitivity was reasonable, some noise was added near maximum gain, but normal input levels should not present a problem; unfortunately, the line input clips at 3.5V (adequate for normal requirements). The mpx filter is permanently in on all input positions, giving a steep fall off above 15 kHz.

Replay azimuth was just slightly out, but replay amplifier noise measured better than usual and showed a good improvement with chrome and an average improvement with Dolby. Some 50Hz and 150Hz hum was noted which was slightly audible. The replay clipping margin is adequate for all normal tapes, and headphones worked well with adequate volume.

The replay response showed slight bass 'woodles', and at HF it lifted gently at 10kHz, but it showed the correct ratio between ferric and chromium. Replay distortion was very low indeed, which is most commendable.

The overall responses all showed marked losses at 10kHz and the bass responses all showed slight bass 'woodles', although averaging reasonably flat. It was quite clear that all the bias levels were too high.

Maxell UDXLI, for example, gave incredibly low distortion at Dolby level, rising to only 1.8% at +6dB, but HF compression was noted subjectively, as well as a muffled sound quality. Overall noise levels all measured well, showing a 10dB noise improvement with Dolby.

BASF LH1 sounded rather better, but also penned HF loss. Sony FeCr measured only 2.2% at +6dB, but produced considerable HF compression and was around 3.5dB down at HF; noise was extremely low, giving one of the best figures.

Maxell UDXLII gave a slightly better response up to 5kHz, but averaged -1.25dB at 10kHz; noise measured well and distortion averaged 2.7% at +6dB, again excellent but some HF compression was noted.

Because of the poor overall response on the original review sample a second sample was checked, and was found to be far better, UDXLI
being almost flat to 15kHz, Sony FeCr however still showed a slight roll-off, but UDXLII was flat again to 15kHz. The bass end in general was rather smoother and distortion and noise levels measured very similarly to the first sample, while 'Dolby in' responses were also very satisfactory on the second sample.

Wow and flutter measured well on the second sample, but HF stability was slightly variable (around average). Speed measured up to 1% slow and 1.6% fast on the two samples, and spooling took 2.2 minutes in each direction. Erasure was excellent and crosstalk generally good, but right to right between opposite tracks was slightly below average on both samples.

Quality control was clearly suspect on the first sample, although the model was nevertheless well liked. The DIN input worked particularly well and the machine was quieter than average. The basic electronic design was generally very good indeed, and considerable attention has been paid by Hitachi to the input pre-amplifier circuits, although they still need some minor points putting right.

Since the second sample had excellent overall responses and was no worse in noise or distortion performance, the model can be given a recommendation, but the model is not quite in the 'best buy' category because of the quality control problems (first sample wow and flutter, and response problems, and speed differences between samples).
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The D900 is a 3-head deck built into a metal case, employing the Hitachi combined record/replay head. All deck functions are microswitch logic operating, and work very smoothly indeed, allowing the user to drop into record whilst on replay in addition to transferring from any one function to any other.

Cassette loading in the hinged front door was very simple and reliable. Two record friction-locked concentric controls are provided for mic/DIN and line input mixing, and there is also an additional ganged output gain control. Lever switches select tape/source, three positions of bias and equalisation separately, and Dolby in/out with multiplex switching. A tape counter, reset and memory control buttons are provided, together with meter switching.

A Dolby tone oscillator is fitted, together with record-calibration pre-sets. Phono line in/out sockets are complemented by two 5-pole DIN ones, monitoring being switchable to the independant one for interconnection with DIN equipment. A remote control socket is also provided.

The mic inputs (two mono jacks with the left providing mono to both channels) were very insensitive, but the clipping level was reasonably good. The DIN input had adequate sensitivity, but barely enough clipping margin, but noise degradation performance was significantly better than average.

Response measured well, but distortion crept up a bit on high input level signals. Although the line input was slightly less sensitive than average, it clipped surprisingly at only 2.8V, but the
noise performance was very good. The mpx filter cut 1.75dB at 15kHz.

On the 'VU' meter position, the indications were somewhat more accurate than usual, but in the peak-reading position transients were only slightly better indicated than with the 'VU' position, but this was felt adequate. The meter sensitivities were the same on both positions, so many users are likely to under-record slightly when using peak-reading.

Replay azimuth was slightly incorrect, but replay amplifier hiss was exceptionally good both on ferric and chrome, giving some of the quietest replay noise figures measured. Dolby also gave the correct hiss improvement, and replay hum levels measured very well.

The replay response on the ferric position showed a slight boost at 10kHz, but was excellent at LF, and the ferric/chrome ratios were correct. Replay amplifier clipping was satisfactory, but just insufficient for iron tapes, and some replay amplifier distortion was noted on both 2nd and 3rd harmonics and some more loop gain with more feedback might clearly be desirable. Headphones (gain adjustable with the replay gain control) were driven adequately with a reasonable clipping margin.

Maxell/Hitachi UDXL1 penned a very flat response up to 16kHz, extending beyond this with a slight bump; 333Hz distortion was 0.45% at Dolby level, rising to just 2.2% at +4dB, which is excellent.

Overall noise measured exceptionally well, giving 9.5dB improvement with Dolby. The subjective quality showed excellent dynamic range, and very good clarity and openness, HF compression being less marked than usual. Sony FeCr showed a slight HF rise on the left channel, but was almost flat on the right to 20kHz; bass responses were generally good. Distortion measured just 2% at -f 4dB, but subjectively considerable spitch on speech was noted, and HF compression was very noticeable. Thus, ferrichrome was not much liked. Maxell/Hitachi UDXLII gave an excellent overall pen chart, and distortion measured 1.25% at Dolby level, rising to 4.2% at +4dB, a reasonable compromise with HF compression, giving an excellent overall quality throughout; noise also measured well.

Wow and flutter measured quite well, but speed was over 1% slow (sample fault?) Spooling was slow at 2.75 mins, and HF stability was average. Erasure was good, but crosstalk just acceptable.

Provided the input clipping situation is compatible with your set-up, this machine will give some very fine overall quality on ferric and pseudo-chrome tapes. The machine can be recommended for its excellent facilities and was well liked by us. It is thus a best buy, especially considering the reasonable price for a high performance 3-head deck.
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Although this is only a budget price model and it has only very simple facilities, in many respects it outclasses several machines at over twice its cost! The front panel slopes up towards the back and incorporates a top loading mechanism which was simple to load; the deck controls worked smoothly.

Two mono microphone jacks and a stereo headphone jack are on the front of the machine, and phono line in/outputs and a 5-pole DIN socket are on the rear, together with a captive mains lead. Small lever switches select Dolby, and two positions each ofequalisation and RF bias; a single pair of mono input faders had rather a short throw, but worked smoothly, no replay gain control being fitted. No peak reading light was provided but the normal meters are slightly faster than average.

The microphone input was rather insensitive but the clipping margin was very good and the microphone circuitry gave subjectively very low distortion.

The 5-pole DIN input had adequate sensitivity and a reasonable clipping margin from a DIN source; almost no noticeable noise degradation was noted and JVC must be congratulated on getting the input impedance correct and so well optimised (one of the few!). No response problems were noted on the DIN input or line input and distortion levels were all well down.

The line inputs are connected to the DIN input via 470kohm and, as expected, clipping was noted at 7.5V. Unfortunately, some noise degradation was noted from the phono sockets at input levels less than about 0.7V, and if you are likely to be using levels higher than 3 V, then ask your dealer to change the line input resistors to 220kohm or so.

Line input levels of, say, 300mV had noticeable noise added, incidentally. Headphone levels (not variable) were well compromised into low and high impedance models, but the clipping margin was barely adequate into 8 ohm models, although satisfactory from 25 ohm upwards. Replay azimuth was quite a long way out and some pre-recorded cassettes would be distinctly blurred, but correcting it was very simple. Replay noise was quieter than average and showed an improvement of only 2.75dB on chrome (not quite enough) which Dolby however giving 10.25dB average improvement. Replay hum levels were all at least good; the clipping margin was also good, and replay distortion was better than average. The replay response on ferric was very good, showing just a slight 10kHz rolloff of - ldB, but chrome reproduced with too much HF, which ties in with the differences in replay noise performance.

The overall measurement on Maxell UDXL1 showed the background noise to be quieter than average, and distortion at a very low level (1.7% 3rd harmonic of 333Hz at +4dB). Notwithstanding these excellent results, HF compression was less noticeable than usual, showing the machine to be extremely well designed and aligned. The response measured surprisingly flat up to 15 kHz, although a slight Dolby level error of +1 dB was noted here which produced a presence boost of 2dB; this was noticed subjectively, but not disliked since it was followed by such a good HF response. At low frequencies however we noted a significant bass loss amounting to - 3dB at 55 Hz and falling continuously below this.

TDK SA had a reasonably good overall noise performance, and the response again extended to 15kHz with only very minor deviations (one of the flattest HF curves). Distortion was a little high though, showing the tape to be slightly underbiased, but HF compression was minimal on our entire test programme. High level modulation sounded just a little bit dirty, requiring the recording level to be set slightly low for best results.

Erasure was good on the left, but only fair on the right, and the crosstalk figures were all excellent. Wow and flutter measured well, and no subjective problems were encountered. Speed was just a little fast, but spooling average while HF stability was better than average.

For its price this machine performed very well, and was one of our favourites. I do feel, though, that the phono input circuit could have been much better with the addition of a switch immediately before the 50k ohm record level controls and this would have given greater sensitivity, no clipping problem and no noise problem. However, the DIN input is well optimised as it stands. Notwithstanding the line input criticism this machine is clearly a "best buy', especially since the overall sound quality was so much liked in the subjective tests.
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This very new model incorporates both the JVC SANRS and ANRS noise reduction systems, which use elements of the Dolby B licensed circuitry. The deck is a front-loader in a metal case, and has phono line in/output and 5 pole DIN sockets on the rear panel and two mono mike jacks and a stereo headphone jack on the front.

The deck functions worked very well, and included a memory counter and an auto start with external switching. The unique record-level metering system incorporates five sets of LEDs which are on five separate frequencies to show a real-time peak-level display, in addition to two normal type meters. The friction-locked concentric record-gain control is complemented by a ganged stereo replay one, and levers control input selection (mike, DIN and line), SANRS and ANRS and three positions each of bias and equalisation. A ganged 5-position equaliser switch permits record equalisation to be varied, which is most commendable. Two buttons operate memory counter and real time display on/off. The level display, although a gimmick, is great fun, and frankly quite impressive.

The microphone inputs had acceptable sensitivity, a good clipping margin, and microphone recorded quality was very good. The DIN input had excellent sensitivity and a good clipping margin, and almost no noise degradation was noted, which is commendable; the input also has a flat response and good distortion measurements. The line inputs were a little insensitive, but no clipping or noise problems were encountered. No mpx filter is incorporated, which is to be deprecated.

The normal metering had an average performance, but the peak-reading display, whilst reading longer transients reasonably well, under-read fast transients quite markedly. Each of the five frequency bands overlapped considerably, so indicators are only a very rough guide. Replay azimuth was quite accurately set, but replay amplifier hiss was rather average, showing a 9.75dB improvement with ANRS, and 11.25dB with SANRS. Chrome replay, though, was quite quiet, and hum levels measured quite well, no hum being noticed subjectively; the replay clipping margin was excellent, and distortion was minimal. Bass responses measured well, but the HF playback equalisations were slightly down (old BASF standards again).

The headphone outputs are compatible for use with almost all types of headphone. Maxell UDXLI penned a very flat chart from 40Hz to 15 kHz in the +ldB equalisation position, although the nominally flat position gave a correct record response (NB replay error).

When SANRS recordings were played back ANRS some HF loss was apparent. 333Hz distortion measured extremely low, reaching oly 2.1% at +6dB, and overall noise was average, but very good noise reduction was obtained with SANRS, ANRS being similar to Dolby. The subjective quality was very smooth and much liked, although piano recordings created slight chuffing on transients unless played back ANRS. Sony FeCr also produced reasonably flat overall charts, and 333Hz distortion measured 1.3% at +4dB and only 2.4% at +6dB. Overall noise with SANRS measured very well, and the subjective quality was liked, although some HF compression was noted. TDK SA produced a chart which showed a slight droop at 10kHz which became 4dB down at 15kHz in the flat equalisation position (+1 would have given too much boost at 10kHz). Overall noise measured very well and 333Hz distortion measured 3.2% at +6dB. The sound quality was slightly muffled at EHF, and slight HF compression was noted, but was not serious.
Wow and flutter measured extremely well, and speed was accurate. Spooling was average and HF stability good. Erasure and crosstalk were both excellent.

ANRS is moderately compatible with Dolby, but SANRS reduces the HF peak energy, under-recording transients, and expanding them slightly on replay, thus sometime producing slight chuffing, but in general with greater clarity and openness of fortissimae. The JVC noise reduction systems are much better now than they were originally, and it would not be fair to be prejudiced against them on Dolby compatibility grounds since overall recorded quality was very good indeed, particularly in the pseudo-chrome position. Provided you are not concerned about perfect Dolby compatibility, the machine can be very strongly recommended, and is a best buy. JVC must have worked very hard to overcome the many problems that were evident two years ago.
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This very basic machine offers only essential facilities but does incorporate a limiter. No input switching is provided, but inputs include microphone (mono jacks), 5-pole DIN and phono sockets (in and out). Insertion of a microphone mutes DIN and line inputs. The machine, encased in metal, is a front-loader and has just two gain controls on the front for left and right independently, these controls being many centimetres apart, which makes fading impossible, and this could be most irritating.

Push buttons select two positions of bias and equalisation, Dolby and limiting functions, the latter, incidentally, having much too slow a decay time but otherwise working reasonably well. Deck functions operated normally and provided direct switching between all functions. Cassette loading was simple and the mechanism neat. The two meters had a fairly poor performance, under-reading transients quite badly. The mpx filter can be switched in and out on the rear panel.

The microphone input sensitivity was barely adequate for speech at 30 cms from the microphone and the quality was slightly scratchy and humrny; the clipping margin, however, was excellent. The DIN input was very insensitive, requiring the record gains to be virtually flat out to achieve full recording level from a standard DIN source. The noise degradation was so bad (with some hum) as to make this input almost unusable. Distortion and response measured well and the clipping margin was phenomenal! The line input sensitivity was satisfactory and no clipping problems were encountered. Again, very bad noise degradation was noted if the gain controls were used at normal
positions (too much gain after the record level controls).

The replay azimuth was set reasonably accurately and replay hiss levels were average on both ferric and chrome while Dolby gave the usual improvement. However, the Dolby noise reduction circuitry was incorrectly adjusted and tracking was relatively poor. Some slight replay hum was noted though the clipping margin was good and replay amplifier distortion was satisfactory. The replay response was quite reasonable up to 6kHz, but fell noticeably above this, the 10kHz response being around 2dB below that at 6.3kHz; the chrome response, however, was slightly more accurate. 8 ohm headphones were slightly too quiet but 600 ohm models were too loud, the clipping margin being satisfactory. 8 ohm headphones also loaded the metering circuit by around 1.5dB on record and the line output levels by 0.5dB - very poor.

Maxell UDXLI produced a slight positive Dolby error and gave a response showing slight bass 'woodles' but otherwise well extended up to 15 kHz. A presence boost of 1.5dB was noted in the presence region but was otherwise reasonable with Dolby in. Distortion measured 0.6% at Dolby level rising to 2% at +4dB, while overall noise with record level at minimum measured very well, but improved by only 9dB with Dolby. Subjectively, the poor input noise was rather obvious overall and some HF compression was noticed on the test program.

Speech spitchiness was also evident, showing the tape to be over-biased, and transients were reproduced rather poorly. Sony FeCr had very high distortion and was not found appropriate, the bias being distinctly too low. TDK SA gave a flat response from 60Hz to 15kHz on both channels, distortion at 333Hz averaged 3% at Dolby level, rising to 8.2% average at +4dB and, as expected, considerable distortion was noted subjectively but surprisingly also with considerable HF compression. Noise (record level minimum) measured quite well but only improved by 8dB with Dolby in, which is very poor.

Wow and flutter measured at 0.2%, which is poor, but speed was only slightly fast; spooling was rather slow, requiring 2.5 minutes. HF stability was average but some dropouts were noted, while erasure was good and crosstalk excellent.

We were all, unfortunately, singularly unenthu-siastic about the performance of this model and we cannot believe that this was due to sample faults. The input noise performance was very poor and clearly the entire input pre-amplifier and record level circuits would benefit from a total re-design. The record level controls were irritating, and as some of the overall distortion figures were very poor, this machine just cannot be recommended at all, and its price is also rather on the high side for the facilities offered.
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This model is primarily intended for use in a caravan or car and inputs are available with special leads for driving it from an external 12V supply (ie. car battery), or alternatively its external mains power supply can be used. Fitted with a car bracket accessory it incorporates Dolby B noise reduction and includes line in and line out phonos, U inch mike jacks for left, right and centre blend and a stereo headphone socket, which delivers a very adequate level into 600 ohm models. Friction locked independently variable concentric record level and replay gain controls are provided with an additional mono pot for the third microphone (all very small). Just a single mono meter which had better than average ballistics is incorporated. Push buttons select Dolby on/off or ferric/chrome switching. (Nakamichi EX and SX cassettes were supplied). Since battery economy circuits are incorporated, the electronics only come up to full operation a few seconds after switch on to play or record. Whilst the mechanical functions were easy to use, the stop button must be depressed to change from play to rewind or back. Extreme simplicity in operation is an essential part of the design and so facilities are only very basic.

Wow and flutter averaged 0.11%, which is good for a 12 V capability machine and the speed was extremely accurately set. Spooling was rather slow taking 2mins 40secs for a C90. Erasure was adequate and crosstalk very good. The microphone input sensitivity was 62mV into high impedance and no noise or clipping problems were
experienced here.

Replay azimuth was quite badly out on delivery, but after resetting this, the ferric frequency response measured very well on replay, showing just a slight treble lift at 10kHz (+2dB), and thus tapes made on other machines might sound a little brittle. Tape/head contact and high frequency stability were excellent but replay noise levels were much hissier than average - possibly due to more treble emphasis than usual being employed in the replay amplifier. Hum levels when the recorder was used with the mains power supply were virtually inaudible and very low when measured.

Distortion in the electronics was also exceptionally low, which is commendable. 640mV output is available for Dolby level and the output clipped at 2.1V. The overall sound quality on ferric tape was generally good and very clean, but whilst the frequency response overall showed a slight dip at 10kHz, but rising again above this, the measured distortion at Dolby level was surprisingly high on ferric at 2.75% rising to 9.5% at +4dB. The machine would appear to be underbiased on record here, and also incorrectly equalised, particularly bearing in mind that replay was slightly up. Nakamichi SX chrome also gave similar response charts, but produced surprisingly lower distortion than ferric of 1.5% at Dolby level, rising to 5% at +4dB.

This, then, is one of the few machines which gave better results on the chrome than on the ferric position, but some HF squash was nevertheless noticed on the former. The overall weighted noise levels were none too good, measuring -51.5dB on EX ferric and -53.5dB on SX. With the limitation of dynamic range produced on ferric tape by the distortion performance and with the higher than average hiss, the overall dynamic range is unfortunately more limited than average. The SX dynamic range can only be said to approximate that of the average ferric on another machine, but is bettered in distortion performance by most ferric high quality cassettes on the better competitive models.

Whilst the overall sound quality was good and clean, particularly on Nakamichi ferric EX, I cannot help but be a little disappointed with this recorder. It clearly has some specialised uses and has basically been well designed. Biasing and equalisation need some attention on ferric, particularly in the record amplifier. Its very small size and neatness will obviously attract purchasers but the price is on the high side.
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Designed specifically to obtain maximum performance from internal battery operation (an external mains power supply is also provided) the recorder can further be operated from a 12V car battery and incorporates Dolby B processing and a record limiter. A program time elapsed counter indicates when required on one of the 'VU' meters, and a preset can allow an alarm light to come on at any required point towards the end of a cassette, thus showing the user that a tape turnover will shortly become necessary.

The machine is very smartly finished and easy to use, and includes peak reading 'VU' meters which under-read a 64msec burst by only 2dB and an 8msec burst by 7dB, thus making it simple to adjust correctly for peak recording level.

A tone oscillator allows both ferric and chromium cassettes to have compatible record/playback calibration levels. On replay, the bass response was correct on both ferric and chrome but a treble rise (averaging 1.5dB) was noted. The Dolby circuit on replay appeared to be slightly mis-set on the right channel, but this was not too obvious when playing back pre-recorded cassettes, since they sounded extremely good with a very extended high frequency response.

The replay noise was about average and more than adequate. The stability and absence of dropouts was impressive and phase jitter also measured well, 10kHz reproducing ±10°. The overall wow and flutter was good for a battery operated machine, measuring an average of 0.12%.
Some hum was noticed if the mains power supply unit was located too close to the recorder, but this completely disappeared when the supply was removed as far as possible.

On ferric Maxell UD tape the distortion measured 1% at Dolby level increasing to 3% at +4dB and this was considered good. The response was not altogether satisfactory, measuring 3dB down at 10kHz without Dolby processing, but flat again at 15kHz; when the Dolby circuits were operating the apparent hole at 10kHz was exaggerated at low levels to be 5.5dB down. It seems that Nakamichi's philosophy of extending the response to well above 15kHz degrades the performance in the important region between 5 and 10kHz and this may not be considered altogether wise. Surely it is preferable to have a flat response at 10kHz, falling off at higher frequencies.

Nevertheless, the sound quality overall was extremely good and the clarity and lack of distortion commendable. Surprisingly, the measured response anomaly did not seem to be too audible subjectively. Nakamichi chrome produced 1.5% distortion at Dolby level rising to 3.4% at +4dB. The response again had a hole at 10kHz (-3.5dB) but recovered to a flat response at 15kHz, thus showing almost certainly that the machine incorporated a resonance at about this frequency. The quality on chrome was very good indeed and the noise performance was excellent being 56.5dB below Dolby level with Dolby switched in. The distortion subjectively was very low and the machine had a brilliance which can only be assumed to be due to the ringing of the peaking circuit thus making up for the loss of response at 10kHz. The ferric noise was not altogether satisfactory, some 3dB bvelow optimum.

Three 1/4 inch mike jack sockets are provided for left, centre and right and had a sensitivity of 222uV into an impedance of 700 ohms. A Sony stereo electret worked extremely well with the recorder, but only just enough gain is available for recording speech with moving coil microphones. The microphone input circuit had an incredible overload capacity of 400mV and even professional capacitor microphones would not cause overload problems.

The 5 pole DIN input/output socket had an input impedance of lOkohms, about optimum, but the sensitivity of 18mV was far below DIN specification, and interconnection with DIN equipment might well be unsatisfactory. Even the rated DIN source would not fully load the recorder, let alone the specified . lmV/k ohm sensitivity demanded by DIN. The clipping margin, however, was virtually infinite. The phono line input sockets had a sensitivity of 60mV into a high impedance of 100k ohms. Only slight noise degradation occurred when the gain control was advanced fully.

The erase was satisfactory but slightly below average and no particular crosstalk problems were encountered. The machine performed very well on batteries although the battery consumption was rather high since a DC/DC inverter incorporated has to raise the input voltage to 27V for the motor. Despite the response anomalies, the machine was very well liked and can be recommended, for it was found very reliable and gave such a good overall performance. The price is pretty high and many users might prefer to consider the Yamaha battery portable as giving better value for money, although Nakamichi's better microphone sensitivity and noise performance will undoubtedly influence potential purchasers. Maxell UDXL I or Nakamichi EX is now recommended for the ferric position.
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The Nakamichi 600 is most unusually styled, the entire front sloping upwards and backwards at around 40° from horizontal. No microphone inputs are provided but a 5 pole DIN in/out facility is incorporated in addition to phono sockets for input and output.

Furthermore, no headphone output is available. A tape selector switches in equalisation etc. for either Nakamichi EX or SX cassettes. A small stereo ganged rotary output level control is complemented by two input controls for left and right, which are followed by a large rotary stereo ganged master record control. User presets are provided for ferric and chrome bias setting, Dolby record calibration levels, and IM replay suppression. Push buttons operate Dolby processing, tape type (bias and equalisation separate), Dolby tone oscillator, mpx filter and IM suppression on/off.

The two record level meters allow a very wide dynamic range to be indicated and are reasonably peak reading, 8mS pulse only under-reading 5.5dB. These greatly assist in the setting of accurate peak recording levels. The DIN input sensitivity measured 67mV into 42k ohms and is thus totally non DIN compatible. The line input phonos gave identical measurements. Very slight hiss was introduced from a lOOmV source, but when interconnected with the average receiver having phono sockets, no noise problems should be encountered on the input circuit. The wow and flutter averaged at 0.09%, which is pretty low, and the speed was extremely accurately set. A C90 spooled rather
slowly in 2mins 38secs. Erase was excellent and crosstalk good.

The azimuth on delivery was a little out on the second sample, but the first sample was very accurate. The second sample was requested because the replay IM presets were maladjusted and an average user would not be able to set them up anyway without the required test equipment. Whilst the first sample was unsatisfactory here, the second one was very much better, although we could not detect much difference subjectively when the button was depressed (it showed a significant measurement improvement though). Whilst the bass end on replay was very flat, the 10kHz response showed a marked rise to +2dB on ferric and +2.25dB on chrome.

Pre-recorded cassettes sounded brittle and hard and replay hiss levels were much higher than usual. Tape/head contact was extremely good as was general HF stability. The first sample had incredibly good hum levels, but the second one reproduced very slight hum on the left channel. Dolby level gave 670mV approximately on each output and clipping was reached at 3.8V. Distortion in the electronics was generally at a low level.

On a ferric cassette the overall response without noise reduction extended to 20kHz on one track, but was slightly down at EHF on the other and even with Dolby in, the response was still very good. The overall hiss level, however, was very disappointing at only -50.5dB weighted ref. Dolby level.

Distortion of 333Hz at Dolby level measured 0.7% with the IM button depressed, and this rose to an average of 3% at +4dB. Subjectively, the overall sound of ferric was superb and almost beyond criticism but, nevertheless, a little noisy. Nakamichi SX chrome gave an incredibly flat response to 19kHz on the left channel, but was slightly down on the right, but still good (without noise reduction).

With Dolby noise reduction inserted a slight dip occurred on both channels at 2.5kHz, but the response came up again at 10kHz. Resetting record Dolby calibration levels would probably have given a better overall response, but this was nevertheless pretty good. Although the dynamic range seemed better on SX, the distortion was more marked on the first sample but less on the on the second one. We still all preferred the sound of ferric tape, but acknowledged the excellent sound quality on SX which was far better than almost any other machine used in the chrome position. Distortion on the second sample measured 0.6% at Dolby level rising to 3% on the left channel and less than 1% on the right. Both were measured with IM reduction in. Nakamichi SX noise measured -55dB with Dolby in.

An excellent machine, then, which is highly recommended providing you are only concerned with recording and playing back your own tapes. Mr Nakamichi insists that he is right regarding equalisation, which thus makes him incompatible with almost every other manufacturer in the world and so who is in step? Although slightly hissy, then, the remarkable sound quality shows this machine to be reasonable value for money.
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