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The Akai 700 Series

The GX-747/dbx and GX-77

The GX-747/dbx and the GX-77 are probably Akai's highest end sets although they don't have a lot in common neither electronically nor mechanically. The GX-77 is the 7" model and was produced between 1982 and 1984.

The GX-77 is the only set to use the "lambda loading system", which provides easy tape threading. The GX-747/dbx is the 10.5" version and can be regarded as a highly sophisticated GX-646.


GX-77 (1982-1984)

The most striking Akai set suitable for 7" tapes. Theoretically it should be the successor of the GX-266II but that's about the only comparison you can make. I think Akai tried to save the down-going R2R market a little by producing the GX-77. It's a small and easy to use machine, which fits in almost any audio closet.

The GX-77 was the first set capable to play EE tapes. Although I have a picture somewhere which shows the GX-77 with a low-noise/wide range switch that version has never been for sale anywhere. Could be some prototype. This set has 3 DC motors. Unfortunately the reel tables are driven by a belt, probably the worst mistake Akai made on this deck. The GX-77 has two capstans but no dual capstan drive mechanism since both capstans turn in the opposite direction.

One advantage about those two capstans is that a quick reverse can be accomplished. The reverse action on the GX-77 lasts only 0.4 sec.

The tape threading system is also very uncommon. The tape is taken up between the reels by means of a loading roller. The 6 heads are also situated between the reels; 3 forward heads facing 3 reverse heads. Because of this loading roller, tape threading is very easy. At the end of the tape both tension arms fall down. The right tension arm activates a micro switch which makes the loading roller go down again. Some older GX-77 sets have a more or less worn out capstan belt.

A problem which might occur then is that the loading roller, which is driven by the right capstan spindle, won't be taken up no more.

The reverse sensing poles are located next to the capstans; they are visible in the first picture. The GX-77 has a cueing switch, a 3-mode timer start switch, a reverse selector switch, a bias adjust and two speeds: 3.75 and 7.5 ips. It has two separated left and right line in level knobs plus one master level.

The GX-77 is one of the only sets which came with a dustcover; this dustover is customised for the GX-77 and cannot be used on any other set. It has two small "envelope" holes so the reels remain partly visible.

Just like the GX-747, the GX-77 has a digital counter. It counts up to 99.59 minutes. Cleaning the heads is very easy since you only have to lift the hinged head cover to approach the heads, just like the older GX-365 and GX-370 sets (a.o.). On the back of the unit there's a 15 V. adapter input to keep the counter position in memory in case the power is turned off. Of course it also has a remote control capability ( via the smaller DIN Socket type ).

The GX-77 has no microphone jacks. Especially for this set, Akai made a separate microphone mixer: the MM-77. The GX-77 has a high resale value. There are two sets of three heads facing three others. You can also notice the loading roller.

GX-77 Specifications

Track system: 4-track, 2 channel stereo system

Tape speed: 3.75 ips and 7.5 ips

Total Wow and Flutter: Less than 0.03% @ 7.5 ips

Frequency response: 25 to 33,000 Hz +/- 3 dB @ 7.5 ips 25 to 25,000 Hz +/- 3 dB @ 3.75 ips

S/N ratio: Better than 63 dB @ 7.5 ips

FFWD/RWD time: 80 sec. using a 1.200 ft tape

Main motor:

Reel motors:

Heads

Erase Head: E4-245 (x2)

Recording head: R4-241 GX head (x2)

Playback head: P4-500 GX head (x2)

Dimensions: 244 (H) x 440 (W) x 227 (D) mm.

Weight: 21.0 kg.

Power consumption: 30 W (JPN) or 50 W (other locations)

Listed New: $ 800.00 (in 1982) and $ 755.00 (in 1984)


GX-747 (1982-1983) and GX-747dbx (1983-1984)

The GX-747 and GX-747dbx were Akai's show-pieces between 1982 and 1984. The GX-747 appears to be the advanced version of the GX-646 although it's construction is somewhat different. Of course the GX-747 has all the functions the GX-646 has but there is more: a digital counter which counts up to 5'59.59 and which is programmable. The user can check time intervals, but he can also program reverse actions, which makes the deck go into reverse mode after a certain amount of time.

The latter sounds a little like the older reverse-o-matic-feature. The "auto-set" creates a reverse cycles between 0:00:00 and the point where the "auto-set" button was depressed. There is also a 'count-up' button which makes the counter counting up even when the machine is in reverse mode.

Although I own a GX-747dbx myself there may be many other program functions which I don't even know about! The function control panel of the GX-747 is the same one used on the GX-77 (see: GX-77); the GX-77 has no auto-mute but that button is used to activate the loading roller mechanism. The auto-mute lasts 4 seconds and cannot be adjusted. The GX-747 has a cueing function as well, just like the GX-77.

The tension arms cannot be locked manually. The GX-747 has two small additional motors which lock and release both tension arms. Unfortunately this takes place by means of a tiny little belt which will wear out after a couple of years.

Although Akai has no parts any more, those belts can still be purchased at most local electronics stores or via the internet. When the tape runs out, the tension arms will fall down towards the deck which activates a micro switch which activates the two small tension arms motors again. Both arms will turn from the deck and will be locked automatically so the user can easily thread a new tape.

The GX-747 has higher feet on its bottom to make room for the door to fall down. Behind this door you will find all switches and knobs which can be found on the GX-646. Because of the door the line and mic knobs are a little smaller but they still have the memory ring.

One other thing the GX-747 and GX-77 have in common is a LED bar meter instead of the conventional VU meters.

The GX-747dbx is just like the GX-747 but it has additional dbx decode/encode pcb's. Remember: the GX-747dbx was not a more expensive version of the GX-747. It was its substitute. Instead of LED bar meters, the GX-747dbx got back the more conventional VU meters. I have been told Akai probably had to omit the LED bar meters because the GX-747dbx otherwise would become too expensive with both dbx and LED bar meters in one set. I don't know if that is true.

Both GX-747 and GX-747dbx have a very high resale value, probably the highest value of any Akai. Well, with the exception of maybe the studio machine PRO-1000 (see: PRO-1000), which is likely to be even more expensive...

GX-747 Specifications

Track system: 4-track, 2 channel stereo system

Tape speed: 3.75 ips and 7.5 ips

Total Wow and Flutter: Less than 0.03% @ 7.5 ips

Frequency response: 25 to 26,000 Hz +/- 3 dB @ 7.5 ips

25 to 25,000 Hz +/- 3 dB @ 3.75 ips

S/N ratio: Better than 65 dB @ 7.5 ips

FFWD/RWD time: 75 sec. using a 1.200 ft tape

Main motor: SCM200

Reel motors: Eddy current outer rotor motor; model: XO24-TD

Heads:

Erase Head: E4-245 (x2)

Recording head: R4-241 GX head (x2)

Playback head: P4-500 GX head (x2)

Dimensions: 483 (H) x 440 (W) x 256 (D) mm.

Weight: 21.0 kg.

Power consumption: 70 W....150 W (depending on location)

Listed New: $ 1300.00 in 1982


This page is under construction ( Like software, the job is never done!....)
Last Update - 6-22-05 7:30 PM.



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