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Akai X-150D

Three Speed Inline 4-Track Reel to Reel Tape Recorder

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Akai X-150D


The cross-field head created a sensation in the tape recorder market by making possible a wide range recording never before heard on any conventional tape recorder.

Using this cross-field head, Akai model X-150D provides a surprising recording performance of 30-23,000 cps at a tape speed of 7-1/2 ips, 30-18,000 cps at 3-3/4 ips and 30 to 9,000 cps at 1-7/8 ips.

What is superior about cross-field recording? How does it differ from typical recording methods as far as construction is concerned?

In the typical recording system, the signal current and the bias current are combined together and applied to the recording head. It is well known that the purpose of bias current is to record, at high sensitivity, a signal applied on the tape, with little distortion and minimizing noise generation. However, the bias current providing such an advantage also has an undesirable character. That is, the wide magnetic field of the bias current affects the recorded signal, resulting in weakening or even erasing the signal. This phenomenon is particularly noticeable at high frequencies.

In the cross-field system, the signal current is applied to the recording head while the bias current is applied to the bias head. These two heads are located in different positions, as determined inter-relatively, so that the magnetic field of the bias will not affect the signal recorded on the tape, even when sufficient bias is applied. This allows the recorded signal to remain on the tape with high fidelity.


Track system: 4-track, 2-channel, stereo/monaural system

Heads: 1 x record/playback, 1 x erase, 1 x bias

Motor: 2 speed hysteresis synchronous

Equalization: NAB

Tape speeds: 1 78  3 34  7 12 ips

Wow and flutter: 0.12% (7 12 ips)

Frequency response: 30Hz to 23kHz (7 12 ips)

Signal to Noise Ratio: 50dB

Input: 60mV (line), 0.5mV (DIN)

Output: 1.23V (line)

Semiconductors: 11 x silicon transistors, 2 x diodes, 2 x rectifiers

Dimensions: 340 x 340 x 230mm

Weight: 14kg

Note: optional 15ips



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Reviewed Dec 10th, 2016 by davidtxotr

Great resource.
Thanks to all that have contributed.
This is my first venture into the open reel's.
I just purchased two X-150D's and hope to be able to bring them back to life.

Reviewed Mar 05th, 2016 by Missel48

Purchased this model in the Asmara, Ethiopia military audio store in 1969. Unit is till functional today; the only maintenance has been belt replacements.
In my opinion, this was one of the best low-priced reel-to-reel recorders of its time.



re: X-150D

Thank you for the manual whomever you are.
I had no idea how to thread this deck and also I have full reels and no empty ones. So once up and running I will post a review or comment. John

re: X-150D

I have this Akai x-150d deck and a number of reel to reel tapes from my fathers estate when I attempted to copy family tape content to a more sharable format on my PC after about 20 min of use the deck motor slowly loses speed.
I discovered hifiengine and downloaded the circuit and service manual although I have a feeling that some pages are missing! otherwise an invaluable resource for the enthusiast.
The motor on the deck was slowing down due to leaky motor run caps there are 3 caps in one metal can and ALL were breaking down around 100v (I have an old Heathkit tube based capacitor checker which can apply up to 600v dc).
I sourced some 450v rated capacitors and made a custom mounting plate with an old fashioned tag-strip to replace the can capacitor mounting, wired it up and motor runs perfectly.
The original cap was 2uf +0.8uF+1uF with a common tag I replaced it with 2uF+1uF+1uF I don't think it is necessary to match the values exactly.
Who ever supplied the circuit and service manual thank you so much.

re: X-150D

I have power to my X-150D (VU meter lights come on) but the motor no longer runs. I smelled a bit of a burning smell when it was last working, which made me think the motor might have seized-up. So I pulled the unit out of the wood case and the motor/fan blades turn freely. When I apply power and manually try and spin the motor, it turns a little but doesn't have enough power to keep going.
Do you think I should replace the motor, or might the problem be the power transformer or the motor capacitor? Any guidance on how I might be able to troubleshoot to be sure?

re: X-150D

My other AKAI reel to reel 1700w works fine for ages then after a while the motor slows down playing at a much slower speed stopping sometimes and not having enough torque to rewind or fast forward. It comes good again after its been off for a while. From what everyone's saying and that behaviour suggests motor run capacitors. Yours might hopefully just be that. Sounds like your capacitors are completely gone. The only other thing is the motor may need lubricating. Sounds unlikely when it turns. I can't recall if the motor ever had problems on my X-150D I know the rewind and fast forward cam is decintegrated on it. The pinch roller is too. Covered in cracks. Both cams are cracked on my 1710w but only lightly so fully functional. The pinch rollers are the same. The rewind fast forward cams should be too. Had my x-150d playing perfectly with the pinch roller from my 1700w. It's handy that some machines share parts. I like the valves and built in amplifier and speakers of my 1700w. It looks really retro and cool too but my x-150d has superior frequency response with its cross field heads. I don't really need a built in amplifier and speakers.

re: X-150D

Player is stuck on slowest speed...any recommendations? The selector switch moves but the tape speed remains the same

re: X-150D

I have no power. Need a schematic on the pwr supply.

re: X-150D

Thanks for the manuals, but I have a problem with the "Play". The machine rewinds and fast forwards, but won't "Play". Don't really want to take it apart unless there really is a solution by doing so.

re: X-150D

I'm guessing you have threaded the tape through correctly. It could be the play cam has a chunk or chunks fallen off it preventing it from striking the lever to engage playback mode.

amirrosi's picture

very good

thank you very much i love this site very much

Thank you!

I will be sending you some manual in return real soon! Thank you so much and God bless!

Need Schematic for Akai X150D

I downloaded the Service Manual, but the schematic was not included in the download. Does anyone have a schematic? The problem I have is that the left record isn't working well. The recorded material jumps around every second or so (randomly) from normal to extremely weak during playback. The right side is fine. Pre-recorded tapes playback fine. Any suggestions?

re: Need Schematic for Akai X150D

It could also be a dirty record volume potentiometer. Both mine were intermittent and scratchy and crackly as can be.

Channel issue in Akai X150D

This machine uses a slide switch to go from record mode to play mode. Take the machine out of its cabinet, from the bottom remove the two small amp modules. This will give you access to one end of the slide switch on the remaining board. You'll know where the switch is by the two rows of solder joints on the bottom of the board. Spray some DeOxit D5 into the switch and work it back and forth to distribute the cleaned through the switch.

schematic for X150D

I have a schematic but the file is more than 8MB.
How i can send it ?

Fabrizio i4YFC

re: schematic for X150D


Can you send me the schematic? I would greatly appreciate it.


ellsworth audio company's picture

Akai X150D L-ch dropout;

juneyg; Hold your finger lightly on the supply reel while recording for a while, if the problem goes away or gets much better, you have poor tape to head contact. That problem can exist due to worn heads or weak reverse tension on the supply reel. On that model and all of those older Akai's with that transport the problem is more likely the supply reel. The felt pads that act as a clutch is to compressed or disintegrated. The factory recomended repair was to replace the entire reel table as one piece. Unfortunately the have not been available for many years. You can try to disassemble the table and clutch and try to replace the felt but good luck with that. Dennis

This website is not affiliated with or sponsored by Akai. To purchase X-150D spares or accessories, please contact the company via their website or visit an authorised retailer.