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Akai 4000DB

Stereo Reel to Reel Tape Recorder (1975-77)

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Akai 4000DB


The 4000DB is an attractively designed compact tape deck offering multiple connections and controls and quality features among which are Akai's one micron gap heads for high density recording and the well known Dolby Noise Reduction System.

Tape Head

Akai's one-micron gap head is responsible for an amazingly important difference in tape recording. It's the difference between ordinary performance and high density quality recording and playback. Ordinary head gaps are from 2 to 4 microns, but the gap of this outstanding head is only one micron. This high density recording system provides excellent frequency response and clear, high pitched sound is generated as a frequency tone and recorded smoothly without distortion.

Dolby Noise Reduction

With the Dolby Noise Reduction System, hissing noise heretofore thought impossible to eliminate, is reduced to a completely inaudible level. Basically, this circuit boosts the low level signals prior to recording and lowers them by precisely that same amount at playback time. During this revolutionary process, the extraneous noise is eliminated, thus also eliminating tape hiss.

Dual Monitoring

A Tape Monitor Switch and three heads facilitate instant comparison of the recording being made with source signals. Easy confirmation of recording quality results in a more professional recording. The 4000DB is also equipped with a front panel headphone jack for monitoring or private headphone listening.

Sound on Sound Recording

Sound-On-Sound is the accumulation of as many individual recordings on a single track as is desired. For instance, record on track 1 and rewind tape. While monitoring the first recording through headphones, record on track 3. Both recordings will merge on track 3. Repeat as many times as is desired by switching Track Selector positions. Convenient for fun or professional use.

Sound with Sound

Record on one track, then rewind tape and record on another track while listening to first recording through headphones. Playback and compare! Especially convenient for repetition and comparison exercises such as when studying a foreign language, etc.

Sound Mixing

Independent line and microphone recording level controls and input jacks enable signals from microphone and line sources to be blended and recorded simultaneously. Record your own vocal style accompanied by your favourite orchestra, etc. Interesting and entertaining.

Automatic Shut Off

Threading the tape through the Automatic Shut-Off Lever and setting the Power Switch to Shut-Off position is all that is necessary to effect Automatic Shut-Off at the end of the tape. A convenient safety feature should the unit be left unattended.

Pause Control

Momentarily stops tape travel during recording or playback. Pause control is especially useful when editing tapes. Simply lift Pause Lever when a certain portion of the program is not desired. Easy Start Button release.

VU Meters

Internally illuminated expanded scale VU Meters provide quick and accurate determination of recording and playback levels.

Sturdy Mechanism

In keeping with Akai's top quality parts utilization policy, the 4000DB also features robust construction and sturdy mechanism. Further, a highly efficient induction type motor assures stable tape travel and ideal starting torque. The characteristics of this motor coupled with a boldly designed flywheel reduces wow and flutter significantly.


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

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

Motor: 1 x 4-pole induction

Reel size: up to 7 inch reel

Tape speeds: 3 34  7 12 ips

Wow and flutter: 0.15% (7 12 ips)

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

Signal to Noise Ratio: 55dB

Total harmonic distortion: 1%

Crosstalk: 40dB

Input: 70mV (line), 0.4mV (mic)

Output: 0.775V (line)

Semiconductors: 27 x transistors, 2 x FET, 4 x IC, 17 x diodes

Dimensions: 406 x 325 x 196mm

Weight: 12kg


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Reviewed Jul 18th, 2019 by pjzzz

Serviced it fully and did a full restoration on this fantastic little Akai and it just sounds great again. Set it up for Recording the Masters SM900 tape and this makes great recordings.
Also uploaded the coloured service manual because the other b/w SM has some badly scanned pages in it.

Reviewed Oct 15th, 2018 by laos76

My father got this machine back in '75 to make compilation tapes from his LPs for get togethers. In 43 years it has never had one fault! The thing is built like a tank!

Reviewed Sep 03rd, 2016 by lowlow007

Low price reel to reel but great sound, 2 speed.
Excellent !

Reviewed Dec 26th, 2014 by Lolek

Operation of each function is perfect, recording on different tapes gives a very good and sometimes excellent results. Not noisy engine and soft operation of the switches give you big comfort operation.Natural voice with very good bass.



re: 4000DB

Hi I have my dad's old AKai 4000DB. it was last used 2 years ago. I recently set it up again and it sounds like chipmunks are singing instead of Ella Fitzgerald. Is there a simple fix or have I set it up wrongly. It doesn't look as though I have. Appreciate any help. My dad would have known!

RebootedElectronics's picture

re: 4000DB

It's quite possible that the capstan still has the 7.5 ips adapter on it and you're trying to play a 3.75 ips tape. If you're new to reel to reels, the capstan is the part that spins as soon as you turn the unit on. You should be able to just unscrew it and move it to the spot above the tape transport so you don't lose it.

Also, if you don't want it to shred your tape at the end of a reel, hit the Off switch once it's going and it will stay on until the tension arm drops, then turn off automatically.

re: 4000DB

Does anyone know it its possible to adapt it to 10,5" with the AKAI EA-10 adapter?

re: 4000DB

I've lost the capstan for my Akai 4000DB, part number MY270055 and screw, part number ZS293027. Any idea where I can buy replacements?

Electronica2314's picture

re: 4000DB

Correction !! I have a 7.5 ins sec capstan and nut surplus to requirements, good condition. Any use to you ?

re: 4000DB

Looking for a 7.5 in/sec capstan and nut. Have you still got it? If not, any ideas where I might find one? Thanks.
Stuart Orme

Electronica2314's picture

re: 4000DB

I have an inch and three quarter capstan sleeve and nut. Any use?

re: 4000DB

My AKAI allthough has no mechanical problems, it seems having a sound distortion on reording/playback. Is it matter of electrolyte capacitors that should be replaced? consider that this machine is almost 40 years old.


Akai 4000 DB

when playing a tape from the beginning it starts out fine then after a few minutes it slow down....
any thoughts on the possible repair?

Akai GX 4000DB

Where can I buy a replacement tape monitor push switch - as I am getting playback on one channel only- cleaning the switch has made no difference

Electronica2314's picture

re: Akai GX 4000DB

This fault seem to be due to a gummed up track select switch. Try switch cleaner. Beware, do not attempt to strip it, it is a nightmare to reassemble, easy to loose v small parts.!!

Allister Hadden's picture

Main Voltage Adjust and Speed .

Yes now have the right drawings for the right model . Lable on the back where the mains goes in say's
AKAI 4000DB serial no E- 20804-021134 . But there is no where to set the voltage as it say's in the manual .
The power from the on off switch is stright into the transformer .via a board with fuse's on it and the other wires off the transfomer go . The wire's for the motor come out off the transformer as well . Mybe they are using the winding
off the motor as part off the transformer . Was damage in transit as it was bought on EBAY . Tape reel shafts bent .
That all fixed the next problem was it was running slow . That when i discovered the differance in the drawings . and wiring . Quick qure was worked out the speed it was runing at then made a new casptan sleve one for low speed and one for high speed ( that one was missing ) Just measured the lengh off tape over a certain time . Then i worked out the actual size i needed to make the new caspstan .
STD 3 3/4 inch/sec = 4.00 MM and the 7 1/2 inchs/sec = 8.00 MM and 14.00 MM long . Material Steel / Stainless .
High quilty surface finnish polished .
Now i will do some recordings on it now once i learn to use it . Totally differnt from the Casstte Tape 4 Track . It to handy . I would like to thank the poeple off hifiengine for there hard work compling the data on the tape deck as with out it might not hve been fixed back to working .
Uless information Below

I have in my possion Radio Servis Manual's 1953 to 1963 all radio manily and some TV in them THey are by H. Hawks they are 6 books 800 to 900 pages in each volume . 6 volumes . Wiring diagrams and fault finding off every make and model off the year they cover . There are hard back dark red in colour with gold letter set into them they where very expensive when new . . Before the day off hifi . I was going to try to down load some off them . But will have to learn who to do that . About 20 years ago on Sunday night there was a metting at my house and things where repaired radio ,TV, computer , video . and build projects like transmiters , data ,earth to space .
Most off us where Ham's well 8 off .

The Books were left to BE USED

AKAI 4000 DB

Purchased AKAI 4000 DB but when try to play the pinch weel do not go up to the capstan. Any solutin please.

re: AKAI 4000 DB

I believe im having the same problem. THe mechanism seems to be jammed. Did you get any replies to your post that helped you solve the issue?


Not recording

I'm trying to record with my 400DB. I've plugged in a guitar (I'm assuming I can go direct in), switch to source, raise my levels, and selected track 1. The vu meter shows it's reading through, I can hear the guitar through the headphones and the record light goes on when select the record option. Playback has nothing. Any ideas? How would i know if it was the heads? I put in an audio reel and am able to hear the sound. I'm a newbie with r2r and could use any help. Many thanks,


not recording

Hi Rick , Have you switched back to "tape" from "source" as you wont get any output if you dont and is the tape you are using to record on oxide facing the heads and are the heads clean. Try recording with the monitor switch set to tape this way you will hear the recording from the tape as its made. as you are new to reel to reel avoid ampex tapes (406, 407 , 456 ) etc as they go sticky and gum up the heads in no time google "sticky shed syndrome" Regards Gordon.

AKAI 4000DB - broken reel shaft

Hi guys,
Thank you for putting up the Service Manual for the AKAI 4000DB. I recently bought one and both reel shafts (the thing that holds the reel) broke off. According to the service manual, it is either the:
MS255600 Reel Shaft B XR103 or
MT255420 Reel Retainer 3R 102 parts that are broken. Does anyone know where I can buy replacement parts to try to bring it back to life?

Thank you so much,



very helpful the downloaded manuals...I have an 4000DB and give me "melancolic" satisfaction...of the hi-fi tape audition/recording.
With all digital sources, my pleasure is to listening carols at Christmas, on this AKAI tape rec/player, conected to hi-fi power.

Tape speed selection on Akai 4000 DB

I can't understand how to select the tape speed. How can be removed the "outer capstan"? If I try all the capstan is removed. Is it available an illustrated guide somewhere?
It's the first reel to reel tape for me, that's the reason.
Any help will be very appreciated

Alberto (Italy)

akai 4000DB speed change

Hi Maurizio:

The capstan is actually 2 pieces:
For the lower speed (9.5 cm/s or 3.74"/s) the capstan itself is a small rod that turns and drags the tape at that speed.

There is a sleeve which fits on the small rod and has a small knob on top, with a thread. Just slide this sleeve onto the small axis, and screw it. This provides the hi-speed (19 cm/s or 7.5 "/s).

To go back to the low speed, unscrew the sleeve and take it away. The sleeve is the "outer capstan" as you call it.
Note: to be able to screw-unscrew the sleeve you should first stop the motor (turn off the deck)

Regards from Argentina

This website is not affiliated with or sponsored by Akai. To purchase 4000DB spares or accessories, please contact the company via their website or visit an authorised retailer.