4-way comparison: The Akai GXC-700 series unveiled!

[Okke 70s]

(All four just out of the egg)​

Lets dive deep!
Under review here is the entire first Akai GXC-700 series. A truly interesting bunch! I got the GXC 710d, 730d and 760d here. We will look at these specific machines and the models in general. From the looks all the way down to the nitty-gritty of it's internal workings. Today I post the introduction. No later then tomorrow comes the part about the GXC-710d, some time later the part about the GXC-730d and so on. Please chime it at any point.

Family tree
I suppose one could write a book about Akai cassettedeck family trees. It appears to me that they consistently flooded the market with series featuring a model for every specific budget and preference combination. Charting out the M-series alone would be a project. But let's stick to the first 700-series. Later they made some MKII versions of the CS-models, and then added some in between, also with GX heads (like the GXC-709d). All to the best of my knowledge, that is. I belief the first series (introduction years about 1976) consisted of the following models:

CS-702d
CS-705d
CS-707d
GXC-710d
GXC-730d
GXC-740d
GXC-760d
GXC-570d

As always, the CS models would have the cheaper sendust head, and the GX(C) models would have the glass ferrite head. Some of you might already know this, but the GX heads are really something! Especially in the early days of tape, the heads would wear out, and had to be replaces over time. But then Akai made a tape head (first for RTR) that was so tough, it just wouldn't wear out. In fact, they bolstered a life long guaranty on every GX head. Heads where expansive, and you can't just -plop- one in, so that was a game-changer. And today it's a more relevant feature then even. With heads only getting older, and substitutes being simply unavailable.

The CS models #702, 705, 707 then. I never owned one, but from what I gather, they are practically the same deck. Each model up has an extra electronic gizmo, like a "limiter" or something. Knowing Akai it would be a decently build decky, but surely these are the step-in models. Zooming farther in on our comparison we come to the GXC-7** models, plus the GXC-570d (not to be confused with the more simplistic GXC-570d MKII). The GXC-570d was a true flagship model, not intended for major sales. It was "the sportscar in the window" if you please, and Akai's answer to the market-shocking Nakamichi 1000. It is the only standing model in the series, but shares most of its internals with the GXC-760d. Narrowing down farther, we come to the wide-body models, making up the sub series of the GXC #710, 730, 740, 760. I wonder if they ever had a GXC-720d in mind..

 

[Bone Yard]

I finally found an AKAI Deck this summer, my 2nd, it's a GX-F60R from 1980? I'd love to have more AKAI but they're pretty rare around here. I don't know where the GX Series fits in since it's a few years newer. My other AKAI is a JDM MC U2 (Sendust), part of an early micro-stereo, it's about 1/2 the width of the GX and the whole stereo probably cost as much as the GX when new. If I had to guess, it dates around 79.

AKAI's were expensive, it's probably the main reason they never showed up at the thrifts, they just didn't have as many around. Without hand counting, I probably have more Technics and entry level Naks than anything else from the 70's, after that JVC and AIWA seemed to take over. My stuff is all locally found with little cash outlayed and somewhat picky.

 

[Okke 70s]

it's a GX-F60R from 1980?

Ah yes, you might say the far successor of the GXC-730d. But in the 'F series (early 80's), which came after the 'M series, that came after the GXC series.

AKAI's were expensive, it's probably the main reason they never showed up at the thrifts, they just didn't have as many around.

They didn't do really cheap, but Akai covered a pretty wide price range I believe. Here in The Netherlands, and I think all of Western Europe, they sold huge numbers. But mostly the low-end models. It would appear they pushed other models in the US then over here. Way heavy on the wood cases, even in to the 80's

 

[Okke 70s]

The Akai GXC-710d I have here

​

Looks&feels
It came in with that "as if dipped in a tub of ****" look. So imagine my surprise when it came out like this; bloddy mint! No scratches, no dents no letter damage, no rust on the piano keys.. "Beautiful James" I call him, by the Placebo song that was on the tape I used for testing it. The silver face plate + wood case housing signals that this is an upper-range model for sure. It also has the wide profile, that corresponds with the with of the other higher-up components. Which then allows for a pretty unique layout, positioning the piano keys aside of the cassette door and in the milde of the deck. I like it! It's an old fashionably heavy built machine, weighing in at 8,8kg. The piano keys have that smooth an heavy feel of actual metal mechanics, and provide the befitting clanging, clicking and banging sounds. If you are in for that real "vintage deck" feel: look no farther! The door is an interesting case as well. Like all models in our comparison, it has that fancy mechanism that pushes the door straight forward first, and then tilts it over. However, unlike the others, this one does so without a demper. It's a bit of the spartan no-nonsens brother of the bunch. It feels like good, stern quality.



Features
Beautiful James here attests to the graces of stylish functionalism. We got the common tape controls, Dolby, a tape type selector (no metal), record levels, counter, door-open and power-on. But this being an upscale model of course means extra's. We have an MPX filter here, and a blinking "tape run" indicator. It's one of those typical Akai features, that came in many forms. This one is just a single geen blinking LED. Slow on play, fast on rewind or fast forward. The '710 also comes with an output level attenuator and a basic "memory" function. Oh, and a single clipping indicator for both channels. A less common feature is the input selector switch. It can be set tot either the "line in" eg. the common RCA connector, or the mic/DIN setting. The stereo microphone-in comes of course with it's own extra op-amp. But then this op-amp is also used to provide a kind of "low level" input on the DIN connector. Perhaps to accommodate backward compatibility with the very earliest tape output connections? It works fine, just be sure to have the record level set rally low.

Inside the machine
Nothing is flimsy in here! All is big, heavy and sturdy. This deck has the basic setup of piano keys, two heads, one motor and one capstan. Not that exiting rally. But, the head is a GX head, and the motor is a massive outer-rotor AC model. The key mechanics are quite unique, bringing the "force" from the keys from the side towards the transport. The transport itself contains a truly big-fat flywheel. Big flywheels are another Akai trademark, but this one takes the cake.. And there won't be feedback from the take-up reel towards it anyway, because the reels are driven by a separate system, from the motor on. The white plastic wheel houses a clutch, that is actually adjustable. Glory! This clutch is to disengage when the tape's end is reached in rewind or fast forward. In play mode the energy is transported from the idle wheel to that mysteriously red rubber, then on to another clutch and the tape pulley. So what we have here is the basic concept for a tapedeck, but worked out really well.



Beautiful James was a bit noisy and shaky in the mechanics when he got here. If I where to make one critical note about Akai mechanics in general, it is that they tend to be a bit noisy in themselves. However, in this case it turned out that the arm holding the big yellow clutch wheel, was hanging just a little lose from the axel where it is attached. I replaced the ring there with an ever so slightly thicker ring and voila! No more retelling and shaking about. In fact it runs very smooth now. That is after a full refurbishment. All elco's, low noise transistors, belt and snares are replaced. And of course all the cleaning, and lubing of pulli's, pots and slider switches etc. The electronics on this deck are a bit more common then it's mechanics. Although the pre-amp has the "ADR system" that should provide slightly flatter frequency response, and a discretely build Dolby amp. It has the infamous low noise transistors and nothing to fancy component-wise. As with most Akai tape machines, the beauty is in the mechanics with the electronics just about keeping up. But we got better components in now.

Performance
Rewind and fast forward are speedy and also make it fullspeed to the end of slightly tougher tapes. It winds up fairly tight then holds a while before it comes to a stop with an enthusiastic "klang!". It is a deck you can rely on. It also runs near perfect on speed. That is great, for a non-adjustable motor with a new belt! Sound quality on playback then. The deck has a nice full sound, and little "vibration" or other tape-role related flaws. Although it is more sensitive to that at the very beginning of the tape. The deck is also sensitive to "hot" recordings. New transistors and persistent demagnetizing took away the real problems there. But especially when recording on "newer" chrome tapes it sounds saturated a bit quick. I have calibrated the deck, as per prescription with low noise tape. There are no trimpots to adjust for chrome tape seperatley. At playback the manual states an error margin for chrome tapes of +/- 2v on the VU meter (each side separately), in addition to a 1v drop. Well yes, it stays well within that but I would like to see a slightly higher standard please. The discrete Dolby amp actually works great. There is less hiss and less distortion in the playback of a dolby recording with this deck then I expected. The 730 has Dolby IC's, so that will make for an interesting comparison. So overal then, it is an adequate recorder for your casual home recordings. And a very sturdy, great looking, good sounding all-you-really-need deck for playback. I like it! This is one of those machines that just feels right.

​

 

[Okke 70s]

The Akai GXC-730d I have here

​

Looks&feels
This one came out nicely when cleaned up as well. Although not as minty as the '710. At first glance this model looks like a '710 with a black tray slapped under it. But for instance the nobs and VU meters are also enlarged to fit the scale of it. Because this deck is huge! To give you an idea: the VU meters are exactly as wide as a cassette box. I do like those big, half sunken meters though.. I'm not so sure about the black-under-flap-with-chrome-sides design. It definitely has a unique look to it. And of course there is the wood case again, piano keys on the side (but now lower). Plus an additional autoreverse mode switch. Yes good people, this is an actual autoreverse cassettedeck, from 1976. Unlike the '710 it has a damper in the push-tilt door mechanism. That it nice. Operating the piano keys however is a bit of a weird sensation. Because the rewind and fast forward keys push the same mechanical system as in the '710. But the play keys, in both directions, are electronic. So they feel and operate a bit different. The stop key is a sort of hybride, that does the mechanical thing if pushed when the deck is winding, and the electronic thing when the deck is playing.

features
It is the autoreverse version, that is of course its great trick. It plays and records in both directions. It can be set to run each side once, or continually. Changing tape direction can be done at any point, with just one push of a button (no need to stop the deck first). And it plays the other side pretty much instantly. It is an early common reverse deck, but Akai dabbled with the idea of contineus tape-play before the concept had matured. May I present you: The utter eccentric Akai GXC-65 invert-o-matic.



I brought this one back from the dead. It was the top model of all invert-o-matic adaptations, with GX head and internal amplifier. Which actually, after full refurbishment, sounded pretty impressive for a 7 WPC amp, with the befitting 12 WPC jetstream speakers. But the coolest thing about it is, that it actually flips the tape around at the end, jacks it back in and plays the other side. I sold it for a good price, but it was still pretty hard to let go of her..

Back to the '730 then. So besides the autoreverse we have the same common functions as on the '710. Except the MPX filter, which has been replaced by a record level limiter. At the back we find holes leading up to "record level" trimpots. It turns out, they adjust the recording level relative to the vu meter readings. So they are used tot make sure the meters properly represent te actual recording levels. The tape type selector is a more common and convenient system, that has one button for each type. Unlike all other versions in the series, that have the Fe-Cr selection switched in with two buttons pushend simultaneously. Overall it appears to me that this installment of the gxc-700 series was made with a specific target group in mind. Aimed at luxury, and particularly for those that want a machine that is easy to use.

Inside the machine
Some of it is familiair, some of it new. The op amp is adapted to accommodate an extra slider switch, that flips the left and right connections between the head and the amp, when the deck runs in the other direction. Normally the tape gets flipped when played on the other side. But not when it just runs the other way around. This deck just slides the head over a tiny bit, leaving it in the same direction to a now reverse running tape. Hense the requirement to electronically flip the signals left and right. Of course the capstan also has to run the other way for reverse play. Unless you have two capstans, and just push the other ones pinch roller up when changing direction. To that end you see here two (of course massive) flywheels in the transport. One for each capstan. Rather brilliantly, it utilizes the same wheel mechanics as the actual double capstan models higher up in the series. Except that the belt is not run around both flywheels, to form a closed loop double capstan setup. No, the belt runs over the one, and around the other flywheel, which as a result now run in opposite directions. I bet a silence fel over the room when one of the engineers came up with that. I also wonder: would it be possible to turn this in to a double capstan, non autoreverse deck? I mean just by rerouting the belt, and whirring up the pinch-roller plungers in parallel. Should you want to.. Because indeed the headblock comes up and the pinch-rollers (or should we say course rollers?) are controlled by relais and plungers. The mechanics for rewind and fast forward are the same as on the '710, driven by that snare running from the far end of the motor pulley. But the take up reel(s) are now simply driven by a rubber wheel running over a ridge on the flywheel. The appropriatie one for the chosen direction comes up with it's corresponding pinch-roller. A nice and clean design. Although there could be a bit more "feedback" from the take-up reel on to the pinch-roller. Making it more prone to vibrations in the sound. I have replaced the electrolytic and solid aluminium capacitors in the power supply and the amp of this one. Snares, bubs, the Dolby LED and low noise transistors where also replaced.



Performance
Fast forward and rewind work just fine. The plunger operated play/reverse system works great! I haven't seen the smallest hiccup in the operation of the whole system once. It works quick, smooth and makes these highly satisfying "klink-kloink-klink!" sounds. Playback is as expected about as good as with the '710, and really above what an average deck of that time would do. It would seem to have a slightly bit more 'wow' then the '710 but noting bad, and like its counterpart no flutter at all. Tape speed is really dependent on the belt. Mine runs just below 1% fast in forward direction, and pretty well close to perfect in reverse. Replacement belts where all to thin, and therefore ran slow. So the original is back in, for now. Which might also explain a pinch of wow.

I was a bit skeptical about it's recording capabilities, but was pleasantly surprised. Operation for recording is slightly different then normal. It's press pause, then press record, and then press the desired direction (and then release pause). The record key will remain down, while the electronic play/direction key never "hooks in". However the green operation direction indicator will let you know what mode the deck is in right now. The large meters and the clipping indicators combined make for a surprisingly adequate level indicator, given the sloppy 'ballast' of the meters. I recorded in both directions continually on a TDK SA-X tape, and it sounds remarkably clear.

Overall it's just another one of those Akai machines that seems a bit quirky at first. But when you use it for a while, you will find it is all very well thought thru and worked out and it just grows on ya. If you are looking for something compact, or a real 3-head recorder, this might not be the one for you. The more minimalist inclined would probably feel better about the '710, as it's no-nonsens counterpart. Otherwise.. This deck is eccentric, intriguing, convenient and sounds pretty decent to any standard. I thought recording would be it's weakness, but it is actually pleasant to operate and really holds up in terms of sound quality. It is easy to see why this is a wanted model.

​

 

[WernerO]

and the GX(C) models would have the glass ferrite head. Some of you might already know this, but the GX heads are really something! Especially in the early days of tape, the heads would wear out, and had to be replaces over time. But then Akai made a tape head (first for RTR) that was so tough, it just wouldn't wear out.

That's what many people think, yes. But gap erosion kills these heads anyway. And they are near-impossible to lap.

 

[Okke 70s]

Well everything breaks at some point, that goes for any part of any machine. But the GX head solved the problem of the head being a "wear part" that needs replacing every so often. And that holds up to this day, with all them other lovely 70's tapedecks becoming useless one by one just because they needs there periodical head replacement.

I always think of that when I see those serieusly expensive NAC 1000's. Beautiful machine! But would you even dare using it intensively? I'm not worried about that at all using a deck with GX heads.

 

[made in china]

Where does the GXC-725D fit in?

I have one on my bench right now getting refurbed. Very well built!

 

[Okke 70s]

Ah yes, the GXC-725 is one generation later. Actually quite different on the inside I believe. Using a DC motor for instance, and a crazy number of belts? I never had one here. What are you going to do with it exactly?

 

[made in china]

Ah yes, the GXC-725 is one generation later. Actually quite different on the inside I believe. Using a DC motor for instance, and a crazy number of belts? I never had one here. What are you going to do with it exactly?

It was given to me, and it didn't work, so I put it in a closet about 10 years ago. Feeling ambitious, I decided to tackle it. Turns out, sometime in it's life it was dropped, and landed on the STOP/EJECT key, breaking off one of the posts inside. That's an easy fix. Also, the take-up spindle was gummed up and not moving. I cleaned that out and it moves freely now. The 725D has 3 belts. Doesn't seem too bad. Very sturdy and well built, all of the mechanisms are about 2-3x heavier than what I have seen in other newer units, and far more serviceable.

Just ordered a belt kit for it, and since I think no one has ever put out a recap list for one of these, I am going to make a cap list for it. I also ordered all new meter/well lamps for it, kind of on the fence about replacing functioning lamps with modern ones....what if they don't last as long??
Once that's all done I will clean it up. Pretty much, appearance-wise, it's 9.9/10, that's one of the reasons I am fixing it. And also because the person who gave it to me also gave me my SX-1050 and HPM-100s, so I reckon I can't just bin the thing. And, I need the practice. I've never repaired a cassette deck yet!

Manufactured in November 1977.

 

[Okke 70s]

3 belts, yes that makes sense. This got me on the wrong foot. https://fiji.desertcart.com/products/138842723-complete-belt-kit-for-akai-gxc-725d It's a great project to fix'm up! I just took a look at the schematic, and it has the hideous 2SC458 transistors (TR1). And right behind them the 'not great either' 2SC1312 (TR2). I would recommend replacing them all with 2SC1845 (or KSC1845) transistors. But especially if you are new(ish) to this, it is also wise to fix one thingy at a time and test before you move on. You could put them in the order though.

 

[made in china]

3 belts, yes that makes sense. This got me on the wrong foot. https://fiji.desertcart.com/products/138842723-complete-belt-kit-for-akai-gxc-725d It's a great project to fix'm up! I just took a look at the schematic, and it has the hideous 2SC458 transistors (TR1). And right behind them the 'not great either' 2SC1312 (TR2). I would recommend replacing them all with 2SC1845 (or KSC1845) transistors. But especially if you are new(ish) to this, it is also wise to fix one thingy at a time and test before you move on. You could put them in the order though.

Thanks! I also planned to go after transistors, but before I think too much I wanted to get the mecha working correctly. I am very confident I will be successful with that.

The GXC-725D is filling-in during my "waiting for parts" idle time, I currently have a SX-636, SX-1050 and SX-3700 at my bench all awaiting parts. The SX-636 had those noisy TO-92 transistors where the leads oxidize and contaminate the junction, I thought there may be similar ones in the GXC.... I will heed your advice and zero-in on those transistors right away!

 

[made in china]

3 belts, yes that makes sense. This got me on the wrong foot. https://fiji.desertcart.com/products/138842723-complete-belt-kit-for-akai-gxc-725d

The belts I bought cost me $30! Jeez, I remember going to the local electronics supply store and picking up belts for under $1 each.

 

[Artie]

As always, the CS models would have the cheaper sendust head, and the GX(C) models would have the glass ferrite head. Some of you might already know this, but the GX heads are really something! Especially in the early days of tape, the heads would wear out, and had to be replaces over time. But then Akai made a tape head (first for RTR) that was so tough, it just wouldn't wear out. In fact, they bolstered a life long guaranty on every GX head. Heads where expansive, and you can't just -plop- one in, so that was a game-changer. And today it's a more relevant feature then even. With heads only getting older, and substitutes being simply unavailable.

That's what many people think, yes. But gap erosion kills these heads anyway. And they are near-impossible to lap.

I remember reading somewhere that while the glass-crystal heads didn't wear per se, they discovered that they did micro-fracture, thus creating a sonic loss worse than simple wear. That article was at least 30-something years ago, so don't ask me for the source. It was also pre-internet, in an audio magazine.

Edit: I should add that I have a cool old "upright" GXC-510D, with the glass-X'tal head, that sounds good.

 

[JRhoBurton]

The 760D is probably my best cassette deck.

 

[Okke 70s]

The belts I bought cost me $30! Jeez, I remember going to the local electronics supply store and picking up belts for under $1 each

yeh well... If you plan to replace all the bulbs of all those SX's you better brace for impact

I remember reading somewhere that while the glass-crystal heads didn't wear per se, they discovered that they did micro-fracture, thus creating a sonic loss worse than simple wear. That article was at least 30-something years ago, so don't ask me for the source. It was also pre-internet, in an audio magazine.

Yes I have heard that before. I'm not sure what to make of it. Could be true, could be a "false flag" from the competition.. I never heard poor sounding GX heads though, or reports of such. But then again that might be hard to determine as a cause maybe?

I have a cool old "upright" GXC-510D, with the glass-X'tal head, that sounds good.

Another lovely deck and eccentric member of the family.

The 760D is probably my best cassette deck.

That is despite some serieus competition it seems! I must say I am also just is love with the '760. We'll get to that one.

 

[WernerO]

I never heard poor sounding GX heads though, or reports of such. But then again that might be hard to determine as a cause maybe?

Microscope. Playback frequency response test from an alignment tape such as MTT-356. It is a fact and relatively wide-spread among ferrite heads. A reason to be very cautious when purchasing such decks. Also other from brands, obviously. Pioneer CT-F1250 is notorious.


https://www.tapeheads.net/threads/brand-new-akai-super-gx-head-decks-are-they-worth-buying.100532/

 

[SDsailor7]

Hello all,
I just bought an Akai GXC 740D how does it compare to the 730D or the 760D? are they about the same? same specs and components inside?
I will have to get new pinch rollers because the existing ones are cracked due to age.
But the deck was cheap, bought it at the flea market.

 

[Okke 70s]

Hello Sailor! If you got a nice '740 for cheap than you got yourself a good deal. I've been looking for one some time now, without succes.. I'll just comment on the '740 in absentia. I have seen one on the inside, and can deduce from knowing its siblings.



The Akai GXC-740d Looks a lot like the '710 on the outside. Except the plastic thingies around the VU meters, counter+reset button are grey instead of black. It also has frontpanel bias adjustment trimmers and they shuffled functions around on those 5 push buttons. Otherwise the exterieur is identical. Internally there are shared components as well, but it's a different kind of beast. The '740 is a three head - double capstan deck. And that is what separates the man from the boys, in cassette land. Playback might be comparable with the '710 and the '730 but it's much more of a recorder. That is reflected in the additional functionality of tape monitoring, and front panel bias adjustment, with internal call-tone generator. But most of all in better tape-role and the alignement benefits of separate playback and recording heads. The '740 is also the first model in the series to accommodate mic and line mixing on recording. The MPX filter is back in (left out on the 730). The only thing not impressive about the deck is that it runs on one motor. That is however another one of those really big outer rotor AC motors. And this one is speed adjustable, because it is not running on the AC frequency.

If we compare spec sheets we see a 1,5% THD given for the '710 and the 730, but only 1% THD for the '740. So that's quite a jump. The given THD is actually the same as for the '760 although the '760 has a better wow and flutter rating. You'd think the one causes the other, so maybe that 1% is a bit of a round off.

Anyway, this installment of the series has the graces of good looks and a very high quality built like all of them. However if you are serieus about making high quality recordings, then this is the one that will get you there. Piano keys and a no-nonsense skills-set might make it look somewhat common to the untrained eye, but it is actually the real deal for recording.

 

[SDsailor7]

Hello Sailor! If you got a nice '740 for cheap than you got yourself a good deal. I've been looking for one some time now, without succes.. I'll just comment on the '740 in absentia. I have seen one on the inside, and can deduce from knowing its siblings.

Hello Okke,
Thank you for posting the specs of the 740D. I like what i see
last couple of days i have been busy cleaning and lubing it. I have found out that i need new pinch rollers because mine have hardened and cracked so i will need to get the old ones re-rubberized and the person that will do the job does not have the dimensions in his data base.

I did powered it up and surprisingly the belts are still in one piece and it turns but due to the bad pinch rollers i did not go any further.
I would like to know if any of the other models in the 7 series have the same pinch roller dimensions? so i can let him know and maybe he has those in his data base.
I would like to get this deck back to life.

Thank you
View attachment 2782407

The Akai GXC-740d Looks a lot like the '710 on the outside. Except the plastic thingies around the VU meters, counter+reset button are grey instead of black. It also has frontpanel bias adjustment trimmers and they shuffled functions around on those 5 push buttons. Otherwise the exterieur is identical. Internally there are shared components as well, but it's a different kind of beast. The '740 is a three head - double capstan deck. And that is what separates the man from the boys, in cassette land. Playback might be comparable with the '710 and the '730 but it's much more of a recorder. That is reflected in the additional functionality of tape monitoring, and front panel bias adjustment, with internal call-tone generator. But most of all in better tape-role and the alignement benefits of separate playback and recording heads. The '740 is also the first model in the series to accommodate mic and line mixing on recording. The MPX filter is back in (left out on the 730). The only thing not impressive about the deck is that it runs on one motor. That is however another one of those really big outer rotor AC motors. And this one is speed adjustable, because it is not running on the AC frequency.

If we compare spec sheets we see a 1,5% THD given for the '710 and the 730, but only 1% THD for the '740. So that's quite a jump. The given THD is actually the same as for the '760 although the '760 has a better wow and flutter rating. You'd think the one causes the other, so maybe that 1% is a bit of a round off.

Anyway, this installment of the series has the graces of good looks and a very high quality built like all of them. However if you are serieus about making high quality recordings, then this is the one that will get you there. Piano keys and a no-nonsense skills-set might make it look somewhat common to the untrained eye, but it is actually the real deal for recording.