OVERVIEW:
This vintage cassette machine dates from the days when Akai were well known for their very high quality audio equipment (for the times anyway) - a world apart from
their later cheap-n-nasty plastic jobbies in later years!
The 310D was aimed at the high end of the cassette market, had very good specifications (for the time), was built like a German battleship and was priced accordingly - these were VERY expensive at the market release time.
I am a technical audio professional so I like to look around inside at these old machines to gaze at the design/engineering/build of these high quality machines. There is some talk that Nakamichi had a hand in the design and possibly the supply of the transport system as well. Take a look at the photograph showing the transport mechanism, quite amazing.
So what is so great about these machines? Well by later standards - nothing BUT at the time of release, these machines were at the "top of the bunch" because of:
a) The famous glass crystal heads (GX) which will NEVER wear out - this machine is no exception, the head is in excellent condition
b) Double capstan transport - very rare in cassette machines at this time (two rubber tyres move the tape across the head)
c) FeCr tape formulation capability, potentially giving a better treble response, higher audio levels with lower noise - high end was specified as up to 17Khz with this tape formulation
d) Rock solid (well engineered) transport system - over 40 years later and this machine still performs without any transport issues.
Unique cabinet design, some would say "very 70's" and others "downright ugly!" - split the difference, it's different.
With all that said THERE IS AN ISSUE, IN MY VIEW NOT A BIG ISSUE BUT PLEASE READ THIS DESCRIPTION FULLY!
Akai Cassette Recorder/Player
Model: GXC-310D
Released to market around 1975
Original retail price (1975) around A$750
Brief specifications:
4 track 2 channel record/playback head
Full track erase head
Large drive motor - AC powered (53V from the AC input transformer)
Wow/Flutter less than 0.07%
THD Less than 3% but typically around 1.5% (depends upon tape type and amount of signal "drive")
Frequency response (best) is 30Hz to 17Khz but with low grade "normal" cassette tape, typically 50Hz to 14Khz
Tape types: Low Noise, CrO2, FeCr
Dolby B noise reduction
115V - 240V switchable operation @ 50 or 60Hz line frequency ***** PLEASE PLEASE NOTE, YOU MUST READ MY COMMENTS BELOW!!! ***
Weight: 9Kg (it is heavy)
Dimensions: 300mm x 440mm x 143mm
AC INPUT POWER NOTES:
This particular version of the 310D was released for the "universal" world market, multi-voltage AC input (110~120 & 220~240) and also switchable 50 or 60Hz operation (for the motor)
The AC input transformer has two primary windings, each handles AC 115V. ONE WINDING HAS GONE OPEN CIRCUIT!
This means that the machine will ONLY run on 110~120V AC input (but at our 50Hz supply frequency so the speeds are correct at least)
The only way to have this running on 240V is to either:
a) Use a step down transformer (240V input to 110 ~ 120V output EARTHED)
b) Replace the AC transformer inside the 310D with a fully working type CWT-2 AC input transformer (NOT easy to find though)
All my testing and running of various tapes through the machine have been at 120V AC input (step-down transformer NOT supplied)
To safely test the machine, I have fitted a NEMA-5 USA style male plug - this will be left on the power lead for the new owner to use.
I have set the rear of the machine to 110~120V operation - it can easily be changed back to 240V operation once the transformer is replaced (if ever)
For those in USA or other countries where the AC power is normally 115V, this is not an issue at all (but you must change the switch on top of the motor back to 60Hz operation otherwise the speed will be incorrect)
But equally, this machine is fine for use in Australia/New Zealand but ONLY via a stepdown transformer.
I hear you I hear you .... "so what do these step down transformers cost"?
This equipment has a power consumption of around 30 Watts, any step down transformer that will happily provide 50W plus will be fine. The step down transformer MUST have an earth pin (round) on the output.
Prices can vary wildly, depending upon the type of step-down transformer but as a guide ... it looks as though a step-down transformer that will do the job fine is available for A$25 here in Australia.
I am not recommending only this step-down transformer, just thought the link may be helpful for those who don't know where to get one of these.
COSMETIC CONDITION:
The case comprises of three main sections, the steel base, the wood veneer side frame and the top solid aluminium sheets (two)
The base is in excellent condition - no dings, no bends and all 4 feet are in place
The wooden side frame (think of a box with no top or bottom) is plywood with an elcheapo plastic based woodgrain veneer. it is also in excellent condition, just a couple of very small edge "dimples"
The top two sections of aluminium sheet are in very good condition.
No bends or horrible marks/scratches but there are some minor/light scratches.
The labelling uses a "transfer style" sticker and these are not terribly durable, MOST of the labelling is in great shape but to the left of the cassette door you can see some rubbing has occurred to the labelling. Shame they didn't use etched labels but there you have it!
Complete with all aluminium knobs/buttons and all are in excellent condition
Cassette door and VU meter clear front panels are clean and not scratched.
These machines use almost exclusively incandescant lamps - ALL LAMPS ARE WORKING i.e both VU meter backlights, Record, Pause and Dolby On
Rear panel connectors (RCA inputs and outputs plus one 5 pin DIN) are in excellent condition
This is a VERY nice looking machine!
TESTING:
First a little history of THIS machine:
Owned by me since around 2000, I obtained it for our audio post production facilities "for fun" it is in no way a professional machine but I wanted to see what these "glass heads" were all about and listen to them.
The specs on this machine were not bad for the 1970's but in no way compared to top flight machines such as the Nakamichi range.
I used it pretty infrequently and even less when the power transformer developed a fault and since 2008 it has been sitting in my storage units.
The first step I took when taking this out of the box is to check the 3 rubber belts - they all appear to be perfectly serviceable with no stretch or rubber degradation. One day new belts will be needed (nothing lasts forever) and I see that these are still available online for fair prices. But at the moment, no new belts are needed.
I cleaned and demagnetised the head - it might be new glass technology but it still needs cleaning and demagnetising of tape heads is a given - this should be done regularly with any machine (otherwise a noticeable drop off in high frequencies can occur).
Both capstan rollers (yes there are TWO CAPSTANS) look to be in great shape, no flat spots but a bit of oxide residue so I cleaned these up.
The metal-metal grease in various parts of the tape transport mechanism lookeda bit "old and crusty" so I cleaned these up and applied new grease.
The push switches are generally fully sealed so cleaning is not really an option (or necessary) but the main PLAYBACK/RECORD multi switch (on the PCB) certainly needed a good cleanup, so it has been cleaned.
All pot tracks have been cleaned
Once all of this was completed, its time to "fire up the beast"
These are well designed and engineered machines and as expected, it flew into life immediately (on 120V AC though)
Fast Forward and Reverse work like a dream - no issues
Play also works perfectly, as does Pause.
Auto stop (end of tape) works although (in my opinion) it's a bit slow - takes a couple of seconds to recognise the tape has reached the end, then shuts off.
Recorded a few minutes of material onto some blank tape, no issues with level controls or either channel - see my photographs with the machine in Record mode.
NOTE: My recording tests were made through the front panel jacks, these are low level (Microphone) inputs with one for each channel. Line level inputs would be connected to the rear of the machine.
Prerecorded cassette tapes sounded fantastic quite frankly, nice wide frequency range - I was impressed for such an old machine.
Eject mechanism is working fine.
I also checked the Limiting and Noise Reduction, these are also working fine.
The tape counter and tape travel display is no ordinary thing either! It uses a rotating cylinder inside the machine which is back-lit. This gives the effect of a row of dots moving horizontally as the tape travels backwards or forwards - probably considered pretty "wiz bang" for the 1970's!
Of course there is still the standard 3 digit tape counter with manual reset AND another button so you can "remember" a particular spot in the tape.
All of these items associated with the tape counter are in excellent condition.
TECHIE STUFF:
I have and can supply the service manual and schematics. Not that a service is needed but it would be helpful if the Power Transformer was being changed OR to optimise the various adjustments. The Service Manual is very readable and extremely detailed, as are the schematics (even with reference test voltages)
If you wanted to change the AC transformer, you need a type CWT-2 - the only benefit of fitting a new one is that you will again be able to run the machine on 240V AC without a step-down transformer.
I spent some time looking around inside this old girl - very spacious inside, well laid out and extremely easy to "work on" - I love it!
While more advanced that vacuum tube tag strip wiring, this machine uses single sided PCB's with all discrete components - absolutely no IC's or SMD!
Lots of point to point wiring, around the main PCB it looks a bit of a "rats nest" but that's how things were done (at the consumer level) back in the 1970's by the Japanese.
Pretty sure these were completely hand assembled, no industrial robots in those days - this is good because it means that a human can more easily "get into" the machine for servicing.
AUDIO OUTPUT OPINION:
Very good sound, for the 1970's that is!
I really didn't expect too much but I was surprised how good these machines sound. My ears used to listen to Tascam and Naka's but this Akai is not too bad.
Stereo imaging is nice and wide, and clean.
I even played some nice piano based Classical music and check for wow and flutter - it's not an audible issue.
Audio levels on both the right and left channels are balanced, both playback and record (setting the input levels to the same spot on the pots)
In summary, a nice (if somewhat heavy) machine which is packaged differently to the standard "box" design - makes it just that little bit special and then there is the glass ferrite head and the shear engineering build quality of the machine, you could certainly do a lot worse in a cassette machine.
Please ALWAYS keep in mind that although I do my best to give as much information as possible and as accurately as possible, this equipment is old and may have issues that I have not discovered .... this is always the case with old second hand equipment.
