AKAI GX-F80: How To Hide A Monster

Submitted on: 17 Mar 21

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Category: Analog recorders/players

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I guess there is no fan of cassette decks who has not heard of Akai decks. The Japanese company, founded after the WW2 in 1947, in still-destroyed Japan, operated until 2001 with more or less success.

The seventies and eighties were the top for Akai, with a large portfolio of devices as well as a specialized professional department.

Although Akai produced almost all standard HiFi components and some of them were very good, fans of audio technology mostly remembered their tape recorders and cassette decks. Looking back, I can think of several models of Akai amplifiers, CD players, tuners and VHS video recorders that deserve serious respect. But almost all of them are forgotten today.

What made Akai so famous? The answer, of course, are GX (and later Super GX) heads they used on their recorders. I have already written about them, and you can see the details here (although just in Serbian).

Akai GX-F80

The GX-F80 was introduced in 1979, with the list price of $ 550. If we compare it to other similar cassette decks, we could say that the Sony TC-K81 cost $ 600 and the Pioneer CT-F900 $ 575.


Akai GX-F80 differed in design from other Akai decks: front loader, but with transport buttons positioned in a rather strange place, that is. on top of the middle part of the device. No other Akai cassette deck offered something similar, and didn’t even use the same buttons. But there are two tape recorders with exactly the same parts:  GX620 and 625.

In general, the F80 was advanced for the time: IC logic controlled transport mechanism, the possibility to run new type of tape – metal, the fluorescent display in two colors, the drive with two motors and, most importantly, three heads.

But beyond that, there is little to add if we don’t take a deep look: no calibration, no sophisticated search functions, no double flywheel in a closed loop … The Akai GX-F80 is a pretty simple three-headed deck.

I must emphasize that the lighting of the interior of the cassette space was done carefully and really great, with a light bulb, of course, so this is one of the rare decks in which you can clearly see almost the entire cassette, as in the picture … a real deck for collectors.

The tape type selector is especially interesting, with four positions (a little more about that later).

The workmanship is solid and it weighs almost 9 kilograms. The inner sheet metal of the case frame is sharp at the edges – it can be inconvenient, although everything else is made precisely enough. The front panel is aluminum, solid workmanship taking into account that we are talking about a cassette deck.

But when I removed the covers and the front panel… and then a beautiful cassette mechanism front cover, I was left speachless.

This deck does not use a single connector for it’s internal wiring. It’s not that I’ve never seen it before, but it should be taken into account that it is a rather complex machine internally. The wires are either soldered directly to the press or the method of twisting the wires around the pins is used – both are inconvenient from the service standpoint. Disassembly of the mechanism is relatively complex, and the cables themselves go on three different sides in bundles. At the beginning, I thought of giving up, but I still continued and managed to get to the engine, flywheel, belt, rubber, idler, etc.

Here’s what it looked like during work – with some parts already removed from the mechanics:

I only had the opportunity to meet similar type of transport once – on the Akai GX-F90, but I didn’t actually serviced it since it had a broken display IC and was impossible to repair due to lack of original parts. The principle of operation of this transport is not as different but there is a large number of metal levers that perform different functions. The transport itself seems indestructible and worked almost perfectly even after 40 years, except for the worn rubber elements that I had to replace. I also removed the grease on all the parts I could reach and put a new one. I didn’t dare to fully disassemble it because it would need disconnecting most of wires and puting them back – in the case something went wrong this may be a never ending story.

Another example is the roller mechanism: on many decks you there is one U-Ring and a spring that is simply to unhook and then remove the roller assembly. On new models the U-Ring and a spring are integrated and made in such way that it is easy to disassemble it in a few seconds. But in the case of the Akai GX-F80 there are three levers that must first be dismantled (each with its own U-Ring). Just look at the picture:

The reel part is equally interesting: instead of standard two brakes (i.e. double brakes) for reels, there is also a third one – for an idler. I’ve never met this before.

Here is the third brake, touching the idler:

The reel assembly, after cleaning and before I replaced rubber brakes:

The heads cover is one of the finest I’ve seen, it’s only better on the Luxman 5K50 which was almost four times more expensive than the Akai. The head suspension is adjusted with three screws, far better than, say, the Pioneer CT-F series decks (900-950-1250).

In addition as the heads are raised and released by a powerful electromagnet, a return shock absorber is installed and the heads are raised quickly but put back slowly. I’ve never met a system like this (Revox transport uses an air shock absorber, but it doesn’t influence the speed of head returning to stop position so much).

In general, transport is really a pearl, both in terms of complexity on the one hand, and the quality of workmanship on the other. For all time, probably. The flywheel is quite massive, Akai never skimped on it with it’s upper line decks.

As a drawback, I would state that there are two belts from the reels: right one goes to the counter and the left to the small wheel with a magnet and a rotation detector – a part of the auto stop mechanism. It is interesting that they did not put everything on the right side of the transport and even saved one belt. Additionally, the biggest drawback of the system is that the deck shuts off when the left reel stops, not the right one – which means that if the deck winds the tape of the cassette poorly (due to an old idler, for example) there will be no transport shutdown until there is serious problem with the tape, and in that case the tape will most probably be already damaged.

I won’t go into technical details regarding the electronics, but the GX-F80 has a fairly large PCB for control and power supply. The “brain” of the deck is located in a small IC that is not even a microcontroller, but a specialized circuit M54410P for controlling cassette decks, VCRs, etc.

What is interesting is that the switching of the recording heads is done by the relay, not by solid state devices.

Adjusting the bias on the audio board is done for each channel separately in the case of normal cassettes, while for other types it is done using one trimmer for both channels – a standard Akai approach even on more modern GX75/95.

In addition to all of the above, there is also a display. It is reminiscent of the classic older type, with two colors, which was very charming at the time.

However, when you look at it, it seems to be defective: the segments turn on and off and there is no peak hold, but often one or two segments are inactive while the third (necessarily the red one) is on. Similar to the common display failure when some of the segments do not work. However, if you set a signal strong enough through the recording potentiometer, all segments will turn on.

The user manual briefly explains something that Nakamichi would spend far more text on: the display is a combined VU / Peak display system. Up to about +1 dB it behaves like a VU meter and recording should be limited to that limit. However, the +3 and +8 dB markers actually show peaks. In fact, this is a system very similar to the Nakamichi 680ZX deck. It may not be that beautiful, but it is very effective.

The aforementioned idea of ​​Akai’s engineers is ingenious. Only a couple of decks (including the 680ZX) display both VU and peak signals at the same time – another example is the analog display on the Aiwa AD6900. Other manufacturers have placed a row of several LEDs next to the VU meters (a classic moving coil instrument). In this way LEDs quick display peaks. Although a good solution, it forces the user to look away from the VU to the peak meter and vice versa. Teac has built one LED diode in Tascam 122 in a VU meter that flashes when the peak is high – in my opinion a better solution. But I really like Akai GX-F80 solution to this and I respect it.

This deck has a manual tape type selector, with four choices: LN, LH, chromium dioxide and metal. The first two labels LN and LH are for normal tape types, where the first means Low Noise and the second Low Noise High Output. Basically, it corresponds to the types of cassettes from the late seventies and has little to do with newer generations of tapes. In that sense, Akai also attached a table in user manual that gives data which normal cassettes are of one type and which are of another, so TDK D belongs to LN and TDK AD and Sony HF belong to LH. Internal bias adjustment is possible for both selected types, which is convenient because the deck has a fixed bias for the user, and two different bias can be fixed: for example LN for TDK D and LH for Maxell UR.



So, what was the condition of this one Akai GX-F80? At first glance, good, and it was like that from the inside, without many traces of someone made a bad repairs. Unfortunately, some of the previous owners ripped out the buttons for adjusting the microphone gain and then made a fine shaft to compensate for the problem. The only thing is that he ended up gluing everything with super glue, and that shouldn’t be done if you want to service the deck because you won’t be able to disassemble it if you want to get to the display, for example.

The mechanics were in good condition, but the belts, idler, roller and rubber parts for breaks had to be replaced. I also refreshed the main engine.

The transport and electronics is completely washed, because there was a lot of dust in the 40-year-old device.

The command keys have become “hard” from the decay of the conductive layer: each key consists of a section on the gold plated printed circuit board which are actual contacts. Here is the picture:


What make the contacts? There are plastic elements and the button itself, and there is an elastic silicone rubber whose integral part is a conductive ring. The conductivity of the ring dropped over time from a few ohms to a few kiloohms. As a result, the button must be pressed much harder until it is permanently damaged. Replacing it with standard mechanical switches from the commercial offer is not at all easy, and it is often impossible or unprofitable.

Here I fixed the contacts with liquid graphite and the result is great – the keys work perfectly, as new. All light bulbs are working, even now, after 40 years. This is how quality should look like!!!

Some of the trimmers have already (ahahahaha, already, I mean after 4 decades) shown signs of failure, I cleaned them and they worked, but I still decided to replace them with new ones. It is interesting that the internal trimmers for record level can be accessed from the bottom of the deck, without removing the cover. This is great if you want (from time to time) to adjust it to the appropriate type of tape. But  GX-F80 had so high sensitivity.

In order to adjust the response to TDK D which I chose for the test, and which is somewhere from 2000, I had to chase the trimmers almost all the way to the beginning, that is to greatly reduce the signal. That’s why I replaced them with new, different values. I could also play with the gain of the recording amplifier, but this way it was easier for me, the effect of changing the total impedance of the next stage of the amplifier remained in the range of +/- 10%.

I disassembled the mechanics as much as I could, cleaned the old grease wherever I found it and put a new one, in this case I chose lithium with the addition of oil, as well as silicone (two types, depending on the application).

I spent about 45 or more hours working on this beast. It took me weeks to get appropriate belts etc. But once the deck started to work the way I wanted it to, I was pretty happy.


The sound

The quality of how the deck sounded the first time I picked it up and how it is sounding now is incomparable – Akai GX-F80 surprised me with the sound quality, I thought I would be just satisfied and nothing more. I was wrong, this is a really good machine. Of course, you have to use tapes it likes the most, just because there is no calibration available to the user.

The bass is similar to old, expensive cassette tape desck: strong, full with a large body, a little round but goes quite deep. Akai decks, at least a number of them, and it is interesting that each one had GX heads, have that specific bass: voluminous, strong, but not to everyone’s taste. It may seem a little lazy, but the bottom line is that it is not – it is just maybe too soft and sticks to the ear. This deck is, remember, made before CD era, so it is the one which should follow main stream turntable sound. Even today, if you have a system that sounds a little bit hard or has small speakers, the F80 will fit into such a system.

The detail of the upper extreme surprised me to a large extent. Akai pulls them out great even on cheap normal cassettes, and it does it in easy and effortless way, which is rare on such old devices to put Nakamichi decks aside. One thing I noticed is that Akai decks from those generations, eg GXC75D, 570D, 740 as well as F80, cannot draw such dynamics on chrome tapes as they can on normal. I guess it’s because the recording electronics was adjusted to the old tapes from the seventies, but I didn’t go deeper into the subject.

The reproduction of the human voice and middle part of audio spectrum is very, very good. Compared to newer cassette decks, such as Yamaha or Teac decks of the latest generation, there is a slight softening of the medium range and it contributes to the feeling of warmth of reproduction and naturalness, although, in fact, it is a sweet trick for the listener.

Another thing was noticeable: a pretty large scene (for one cassette deck), completely unexpected for such an old device.


The conclusion

This is a monstrous machine, made very strong, made to last… but quite complicated to service. It’s not an Eumig CCD when it comes to working on transport, but it’s one of the more complex I’ve come across. Too bad it doesn’t have a direct drive engine and closed loop dual capstan – I think it deserves it. Calibration would also be useful… but then what would be left for the GX-F90?

Recommendation, if you come across a serviced one or You have a good service technician… or if you are still playing with toys from your early days, like me.

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