I have over the years collected together a LOT of quality audio equipment due to my business activities in pro audio post production and general electronics but the day has finally arrived!
My wife says "for goodness sake, get rid of that mountain of gear" so them's my orders ... out they all go.
My NAD gear all found new homes, now it is time to start evaluating the Technics, Marantz and Akai gear I have...
This equipment DOES have issues (see my summary below then details follow that summary), and it is extremely important that the complete description is read in full
THE CONDITION OF THIS EQUIPMENT IS CLEARLY STATED ON MY OWN WEBSITE (HERE), BOTH COSMETICALLY AND ELECTRICALLY
There is no warranty, there are no returns - but I am very thorough and do not "gloss over" any issues I might discover!
SUMMARY
(For those who don't wish to read all the waffle)
COSMETIC: obviously 2x knobs are missing
1x Optical input socket missing the dust cover
A couple of marks on the casing, nothing serious with NO "drop damage"
ELECTRONIC:
Right channel needs work/service on the power amplifier - Preamp on both channels works fine
Digital inputs work fine
Well worth service on the Right Channel, great that no-one has already been playing round inside! I strongly suspect other AKAI equipment will have the two knobs with the special fitting. I looked at Technics but they do not suit.
These are very highly regarded and sought after amplifiers from AKAI and provide great sound while maintaining a pretty good re-sale value.
This asking price INCLUDES shipping anywhere around Australia (I ship all orders over $76 FREE SHIPPING)
AKAI Stereo Amplifier
Made In Japan
Model: AM-M939 [B S] UK & Australian model
Serial # 30865-05282
One of Akai's "premium" top of the line product releases
Champagne Gold finish
"Walnut" Wooden side panels
Analog amplifier but with DIGITAL inputs for the likes of CD or MD/DAT
MIDI (Compact) format
Measures: 385mm wide x 139mm high x 330mm deep
Weight: 10.5Kg (unpacked) 12Kg (packed)
BASIC MANUFACTURER SPECIFICATIONS:
Power Output: 80W per channel (into 6 Ohm impedance load)
Most "standard" loudspeaker systems are designed with an impedance of 8 Ohms so in reality the Power output is more likely to be around 60W per channel using an 8 Ohm speaker system.
Design output load impedance range: 6 ~ 16 Ohm
Damping factor: 30
Total Harmonic Distortion (full power 8 Ohms) Analog 0.008% Digital 0.003%
Frequency response: 10Hz ~ 60Khz (Digital 5Khz ~ 20Khz)
Signal To Noise ratio: 85db ~ 100dB depending upon the input used
Channel separation: 60dB Analog 90dB Digital
Inputs (Analog):
Phono (MM)
Tuner
DAT/Aux
DAT
Tape
CD
Inputs (Digital):
CD (44.1Khz)
DAT (48Khz)
Both digital inputs can be either SPDIF Optical or Coaxial (RCA)
Digital output is available (Coaxial only - RCA)
Processor analog input and output access for connection to external equipment
A & B speaker outputs, binding post style connectors
COSMETIC CONDITION:
Casing is in great condition...wooden side panels are not scratched although there is a couple of small "chips" on the edges of the veneer but overall this still looks very presentable. If you hate it, just take the wooden side panels off so the unit is all Champagne Gold.
All metal case used for the amplifier, including the front panel.
Small dent on the top case, in the centre near the front edge - this is SMALL.
No significant scratch marks to the rear or front panel.
Noticed that one Optical connector is missing the dust cap - no big deal.
No damage to the labelling on the front panel
HOWEVER - two knobs are missing! Both are used for the switching. One switch looks after the PLAYBACK MODE (Source - Off - Digital) of analog or digital signals and the other switch is the RECORD MODE selector. These are knobs with side finger flat spots, fitted onto a special metal 1/4" shaft that does NOT use a grub screw but instead has a slot cut into the end of the shaft onto which the knob fits - a bit special (keep in mind it need to be Champagne Gold colouring as well)
Diameter needed is 22mm, AKAI part # SK-374629 (both switches use the same type of knob)
I do have some "similar" knobs but most use grub screws (not much good in this situation) or are slightly too large. So, these two knobs or substitutes will NOT be supplied.
Nice layout Akai, very orderly and it all makes sense to look at! Quite a bit tidier than some of the NAD's I have been evaluating recently.
Big fat Nippon Chemical filter cap's (10,000uF 85V marked as AUDIO GRADE on the can)
Lovely high current power transformer to the left side (why oh why to one side, making the amp "lop sided" when carrying - Rotel had the best idea, put it in the middle.
No signs of component stress at all
No signs of anyone "ham fisted" modifying or repairs to the equipment - it looks untouched.
TESTING:
The part that really matters!
Prior to connecting my precious test loudspeakers, I checked both outputs for any dreaded excessive DC voltage being present, one channel is as it should be but the Left channel shows slightly high at 200mV which is not terrible but needs attention.
Never ever should you see any substantial DC voltages at your amplifier speaker outputs because if you connect your prized speakers to such an amplifier, your speaker voice coils suddenly turn into little heaters and then go POOF! This is something you must prevent at all costs - ALWAYS check an unknown amplifier for DC at the speaker outputs before connecting your speakers.
I decided to connect my test loudspeaker system briefly to at least get an idea of power amplifier functionality (or not)
This amplifier uses a pair of 2SC3855/2SA1491's (Sanken) in each channel output, these are originals and have never been changed (any service work, not matter how professional always leaves behind little tell-tale signs of work having been undertaken)
DC offset is not correct, measured at the loudspeaker outputs
Left channel 4mV
Right channel 200mV ***
Check and adjusted the DC offset (very easy)
Left channel now 20mV after warm up (was 18mV anyway)
Right channel now OmV - adjustment had no effect at all, here is a problem!
*** Looks like the Right channel has issues
As mentioned above, I am not supposed to be undertaking fault finding on this gear (my wife does not want me to spend lots of time on this gear) but while I had the base plate off and was "sniffing around" I made these measurements
LEFT
2SC3855
E 13mV
B 580mV
C 50.1V
2SA1491
E 6mV
B 590mV
C 50.1V
RIGHT
2SC3855
E 13mV
B 260mV
C 50.1V
2SA1491
E 13mV
B 260mV
C 50.1V
That's all I am going to do, I will supply the schematic which is very readable and does have all test voltage points showing - nice!
While the Right channel doesn't look good, I am happy enough to hook up the audio sources and loudspeakers and see what we get ...
Power ON
LED indicates RED (power on), speaker selection indicates, source input indicates.
That reassuring slight sound of the protection relay going "click" occurs after around 1 second and at this time the power on LED changes to GREEN
First test using a Marantz analog/digital CD player
NOTE: All input selections, muting etc are "soft touch" buttons - the switching is undertaken electronically not physically.
Analog audio first, applying to the Tuner, Tape, CD inputs successively - as each is selected at the front panel, a small Green LED indicates which input is active.
All switching working properly and such as great sound ON THE LEFT CHANNEL ONLY (as expected - see above) The Right channel is trying it's hardest but just a horrible distorted and weak output on this channel.
By great sound I mean GREAT SOUND! Nice, clean and full of "punch" - wound up the amplifier and it effortlessly handled the extra power demands.
The tone controls (3 of them) all function fine although I did hear some rotational noise, particularly the centre BASS control - needs a good squirt here!
Volume control is smooth and noiseless in operation
Same goes for the balance control *** special note
AKAI is just a bit different here - instead of the Balance control being placed near the Volume control, they have put it way over by the Power switch!
Muting works fine, indicates when activated
Next is the PHONO input, this one lacks any flexibility regarding loading or cartridge type - just the common Moving Magnet type.
Working fine, acceptable audio but not up there with the NAD Phono preamps - but perfectly acceptable.
Now let's go digital
Using the same Marantz CD player but with the coaxial digital output, switched the AKAI to digital (the one with the knob missing) and hey presto! a large green panel lights up 44.1KHZ and I have audio. Actually the audio is noticeably "sharper" when using the digital input
I also plugged this digital signal into the DAT input and yes, I got the same audio but this time the display does keeps showing 44.1Khz, as it should. This digital input is capable of 48Khz conversion but I then ran this through my Digidesign rate conversion equipment and yes, 48Khz on the DAT input works fine (and indicates the rate as 48Khz)
