EQUIPMENT HISTORY:
Everything I am describing below is IMPORTANT, read it please!
This amplifier is part of my "collection" of all things audio, both professional and consumer gear. I like to listen to all types of audio equipment, look inside and see the build quality and just appreciate the engineering skills (or lack of) in the early days of audio equipment.
Since around 1990 this amplifier has been sitting in the "back shed" OMG! I hear you say...
I cannot possibly use everything I have and my professional activities in audio post production always took precedent, so this amplifer (and a LOT more gear) sat in the shed waiting for me to "come a callin""
Well, my wife says "for goodness sake, get rid of that mountain of gear" so them's my orders ... out they all go.
Some equipment could well have issues, some will be perfectly fine - my description is extremely detailed and I leave it up to the reader to make their own judgement.
This equipment is old/vintage, to expect it to be "like new" is simply not realistic BUT if you are into restoration of classic equipment for your own purposes or re-selling, this gear could be what you are looking for!
THE CONDITION OF THIS EQUIPMENT IS CLEARLY STATED BELOW, 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!
If I come across issues with I feel would make the equipment "not worth restoring" then I would part it out. The fact this amplifier is offered complete means that no matter what the condition (see below) this is still a very worthwhile restoration project.
If it doesn't work correctly, all is not lost. I am very big on conservation and sustainability so many of the parts can still be used to bring new life to other vintage equipment - keep this in mind.
SANSUI AU-7700 Stereo Amplifier
Made in Japan
1973 ~ 1976
Sansui remains very highly regarded amongst the audio "die-hards", particularly the earlier models when the company wasn't under such pressure to "cut corners/cut costs" to compete in the world of quality audio.
So what do other folks say about this amplifier, LOTS! If you Google search this model (SANSUI AU-7700) there is plenty of comment about this model from Sansui, common comments are "fantastic stage presence" "lots of grunt, even better than a NAD!" and "sounds better than my tube amp!" (hmmm... take that one with a grain of salt though!)
HERE is a starting point for you to read all about what users think!
TECHNICAL SPECIFICATIONS:
Multi-voltage input - this amplifier is the Australian release but it can be switched for use in Japan, Europe, USA
Power output: 54 watts per channel into 8Ω (stereo)
Frequency response: 10Hz to 50kHz
Total harmonic distortion: 0.1%
Damping factor: 30
Multiple inputs:
Two tape decks
Two turntables (with 3 position load impedance selection)
Tuner input
AUX inputs
SPECIAL NOTE: Notice the orientation of the rear panel, this is quite unusual (and very convenient) so you can actually read which input is which by leaning over from the front!
Unused inputs/ports have little rubber/plastic protectors - I WILL be supplying these as well (original Sansui's) because with those sockets looking upwards, while it might be convenient for making connections but with those sockets facing upwards, they then become little "dirt holes" if you don't cover them!
Extremely flexible tone adjustment system (Bass, Mid, High)
Selection of filter settings both Low frequency and High frequency
Switch selectable Pre-amp to Power amp connection or leave them separated if you are using an external Pre-amp, Power amplifier or other external equipment such as a powered sub-woofer.
Input sensitivity: 2.5mV (MM), 100mV (DIN), 100mV (line)
Signal to noise ratio: 75dB (MM), 85dB (DIN), 85dB (line)
Channel separation: 75dB (MM), 85dB (line)
Output: 100mV (line), 30mV (DIN), 0.8V (Pre out)
Speaker load impedance: 8Ω (minimum) DO NOT RUN THIS INTO YOUR 4 OHM SPEAKERS, YOU WILL COOK THE OUTPUT TRANNIES!
Dimensions: 434 x 130 x 315mm
Weight: 12.3kg (packed weight closer to 15Kg)
COSMETIC CONDITION:
First glance, not too bad at all.
Front panel is clean, all lettering (silk screen) is undamaged and perfectly readable.
Knobs are all present and clean, some light aluminium oxidisation noticed on the solid aluminium knobs (those with the side finger recess) but the aluminium knobs with the internal plastic insert (knobs and switch paddles) are very nice.
Side panels are clean although some light "spotting" can be seen when I look at them closely.
Top panel has some light discolouration and this looks like rust from dampness. I have removed all panels and none of this rust is showing INSIDE. So at some time there was a source of dampness or high humidity in the shed!
The rear panel is much the same, it is not terrible but you can see it through the black paintwork. Most noticeable is the two rows of RCA connectors, definitely the nickel plating has suffered light ~ medium corrosion. For the purposes of testing the amplifer I can cleaned these up but if it was me, one day I would be replacing this whole RCA strip (not that difficult) - those inputs are pretty important to keep the noise levels down, particularly the phono inputs.
So to make it clear, they are bright and shiny but a bit dull! You could clean them up further, buff them too but I haven't taken the time to do this.
Base panel is fine, no rust observed.
All of these "clues" lead me to conclude that the amplifier was in a bad position in the shed, not disasterous but not good either!
No screws are missing - this is very important! Often if someone has been "playing around" with an amp, they will leave a screw or two out or worst still, mount the panels the wrong way around! Doh!
The all metal frame, panels etc are all straight and true with no dents or even scratching! The frame is the correct shape and all panels fit together properly - this equipment has never been dropped or had other equipment dropped onto it!
Next (with some trepidation) I take a look inside ...
Trepidation because I didn't know what to expect. I know I haven't been "inside" this amplifier but one of my staff might have without me knowing (it happens)
Removed both the top panel, side panels and underneath panel (very easy to do, remove the side panels first)
All steel is used except the side panels which look to be diecast metal (aluminium?)
Wow! very nicely laid out and best of all - CLEAN! In fact I was very surprised as this is so clean. No dust all over the boards, even the laced wiring is dirt/dust free and most importantly I can see no signs of dampness affecting anything except for a very light rust mark on the top of the AC power transformer - that's all.
I checked very very carefully for signs of water damage on all boards, switches etc and absolutely nothing seen. Just for good measure I gave it a good "dust and suck" to ensure no dirt is lying around.
Next I electro sprayed all switch contacts and the pots. Surprisingly NONE are sealed units, this spells trouble - surprised that Sansui did this. I noticed these strange fuse holders on two of the control shafts, they serve no electrical function at all - the weirdest place to put a couple of fuse holders! Left them alone anyway.
The nice big filter caps are Nippon's - very nice. The smaller on board capacitors are also Nippons.
No capacitor shows signs of bulging or leakage externally.
No fuses are "blown"
All resistors (now these are VERY OLD "cracked carbon" types) show any signs of stress at all, not even the wirewound's in the power amplifier section.
No heat or burn marks on the PCB's
ALL transistors in the power output section are ORIGINAL and have never been replaced! It is easy to tell if someone has been playing around here, they always leave tell-tale signs of white thermal grease where it should not be - this power transistor strip is very clean and original.
In fact, I have looked at the topside and underneath all PCB's and no component has been changed at all since it was first released in the 1970's!
Australian power lead is in good condition, no "nicks" to the sheath and this is earthed equipment (proper power Earth to the chassis) Fitted with a moulded Australian plug.
If I was to make any comment about the power lead, it runs through a rubber grommet and is simply "knotted" inside the equipment - not the best way to secure the power lead but I guess that's how things were done back then.
TESTING:
Yeah, this is what everyone wants to know! (Finally)
I ran all of these tests with the covers off, I want to see if anything strange is happening (e.g smoke!) or strange smells!
To begin with I have tested the amplifier as two separate sections - the SEPARATE switch has been activated.
I used a spare NAD power amplifier to check the Preamplifier section only.
Plugged it in, on comes the Red front panel LED - all good.
1 ~ 2 seconds delay then that lovely "click" from the protection relay.
With no input I listened for "noise" - not a sound!
But that said, while testing with the NAD power amplifier turned on and then switching on the Sansui, you get a decent "thump" through the NAD Power Amplifier as the Sansui powers up. In normal operation you wouldn't hear this because of the protection circuit anyway.
Next I ran a CD player into the various line level inputs, every line level input has been checked.
Wow! is all I can say. Why wasn't I using this more often? What a GREAT sound (remember this is the preamplifier only)
I can smoothly and effortlessly adjust the volume, balance and tone controls.
The audio is SO GOOD!
Ok, that is with the CD source material so I thought "the phono is probably pretty dodgy" but I was so wrong on this count as well.
The NAD phono preamps are well known for their quality audio and this Sansui phono preamp section is right up there with the NAD. I played a bit of vinyl using BOTH phono inputs and they are working great as well. I made sure the input loading switch (3 positions) was operating although to be truthful I couldn't hear a big difference in the audio anyway.
I love the tone side of things in particular because you can really zero in on the frequencies you wish to enhance or reduce.
You see you can set the frequency band with the paddle switches (150Hz, 300Hz, 600Hz, 2Khz, 4Khz & 6Khz) and then use your triple controls to vary the response within your selected range - it lets you get a very "tight" control of the tone.
Hi and Low frequency filter switches also working fine.
Mute (two different settings) works fine
Bass Boost or Mid & Bass Boost work a treat
Switching inputs is noiseless (no thuds or clunks in the audio) and all controls give smooth control WITHOUT NOISE! That means no scratching or one channel dropping out.
To be frank (but I'm not Frank, I'm Russell) I was very surprised at the audio coming from this unit. It has been sitting quietly in the shed for so long but now I know it was dying to "sing" again!
OK, so the preamplifer is 1st class - going well and sounding very "on top of the world", now its time to check out the Power Amplifier side of the Sansui.
I disconnected the NAD and enabled the link on the Sansui between the Preamplifier section and the Power Amplifier .... holding my breath!
Well, I am very used to professional PA power amplifiers giving up the ghost (usually because they have been abused, shorted outputs but sometimes they just "fail")
NOT THIS ONE!
I patched the Preamplifier to the Power amplifier using the rear switch.
Before connecting speakers I checked both channels for signs of any DC voltage! There should never be DC at the outputs and if there is, disaster will result for your speakers (the voicecoils will cook).
The speaker connectors are the spring loaded types for light to medium thickness speaker cable or use a "pin adaptor" if you are using big fat monster cable.
No bad looking voltages on the outputs, so I connected up my Vifa's and selected the music source.
No disappointments here either, solid UNDISTORTED sound! I wound up the volume and the audio remains consistent and does not break up.
I have been running the Sansui for a couple of hours now, at a medium listening level (the neighbours will get upset if I wound it up) and then "touch felt" the heatsink and transistors for signs of overheating. None at all, yes they run warm but definitely not hot!
I read somewhere that if pushed hard at high volume, these AU-7700's may get a bit "hot under the collar" but I cannot vouch for that, the heatsink is very large and seems adequate to me.
SUMMARY:
Although a bit worried about the signs of dampness or humidity that I have noted above, after the full testing I have undertaken I am very confident that this amplifier actually has no operational issues at all.
That said, ONE DAY those capacitors MAY fail (nothing lasts forever) and if you are not careful with the outputs you could fry an output transistor or two but like all good equipment, treat it with respect and it will just keep on keeping on!
I notice that the Service Manual (free) and oddles of information about this equipment is available online so if ever a service was required, it wouldn't present a big problem and from my perspective, this is one very nicely engineered piece of audio equipment that would be quite easy to work on - if ever it came to that!
So, I ask myself, what is a fair and reasonable asking price for this old girl?
I see these generally are being sold for around US$500 ~ US$1200 (damn that's a bit expensive!) with non-working AU-7700's going for US$250
This Sansui AU-7700 is working GREAT!, not just fine but there are those cosmetic blemishes from past dampness so I have tried to strike a happy medium on the asking price.
Please don't forget, that when shipping via my website (this one) I will ship FREE because it meets the conditions for shipping at no cost - this applies to anyone in Australia OR New Zealand.
The free shipping is automatically applied in the checkout area of this website
Although heavy, I am very well versed with safely packing such items and it will be shipped safely - FULLY INSURED
