Little Sansui AM-7 Amplifier

Fairlane

Fairlane

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Neat little amplifier and matching tuner I picked up lat night on CL for $25 bucks.
Not a lot of information out there on this little guy but it sounds surprisingly good to me. Maybe it is the Wharfedale Diamonds I have hooked up to it but this little Sansui is worth a listen if you find one. I might use it in my office for a while or the workshop.

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Nice score!

I have an A-M9 that looks like your amp only a little taller I believe.

I agree with your assessment: sounds surprisingly good. My A-M9 is rated 70wpc RMS 20-20kHz (from the service manual). Now I am not saying that 70wpc is equivalent to Sansui AU-xxx 70wpc. But the little (sub-standard size) A-M9 can carry a bass line like a much larger amp. It is fairly densely packed inside and has relatively high voltage rails @56.5v.

Unfortunately, I did a stupid thing and blew the outputs on one side of mine. So it is in the rebuild queue and will, at some point, become a thread either in the DIY or the Sansui Forum.

You are right about there not being much info out there. I have searched several times and came up with almost nothing. I was lucky enough to find a Service Manual on eBay (I think) and grabbed it immediately.
 

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I didn;'t know they made toroidal transformers in those days,, must have.. Seems that today they are the rage. I have a few power amps with the toroidal,, Seem heavier. What is the pipe in the heat sinks I have seen that before but what is it?? Does it have a nice sound?
 
Roger, that is very cool. Mine does not have the toroidal transformer just a sturdy little heat sink and four power transistors. Worth some effort to get it going I would say. The only thing I could find on these is some "expert" knocking it as cheap and from a time when gear in general was in decline. It probably was when these were made but I am surprised how nice it sounds for what it is. The tuner is a trip, when I get a little more time I will explain how it works.
 
The A-M9 is heavier than it looks, based on size alone. The pipe, I assume, contains either a gas or liquid that helps to dissipate heat from the output transistors. I had an Akai AM-U55 amp with a similar set-up.

Fairlane, does your amp have this same type of heat-sink? Can you show us some pics of the inside?
 
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That's heat pipe technology, like the stuff used in PC graphics cards.

hammondcrazy said:
I didn;'t know they made toroidal transformers in those days,, must have.. Seems that today they are the rage. I have a few power amps with the toroidal,, Seem heavier. What is the pipe in the heat sinks I have seen that before but what is it?? Does it have a nice sound?
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Rodger, I will post some naked pictures tomorrow or this weekend for sure.

I was going to do that but I ran out of time the other night. Fortunately I have been very busy at work so it cuts into my play time :D
 
nice looking components...and the little wharfedale diamonds are a classic in their own right.:thmbsp:
 
MeloFelo, love the name. I did not expect much from these little guys when I picked them up on Craigslist. Knew the Wharfedale name certainly but initially thought these were going to be cheap little book shelf speakers, boy was I wrong. These are quite simply over achievers in my opinion, I have used them in my office, in my garage with a NAD amplifier at home in my Hi-Fi room and with this little guy. Great for rock, jazz, classical what ever you are into they sound great. Not a lot of information about these since these are the very first model Diamond back from the 80's I believe.
 
Thanks for the nice pics Fairlane.

You do have a sweet little amp/tuner set there, especially when you consider the price :thmbsp: And the Wharfedales look great too.

I am glad that you have posted this thread, having been unable to find any info regarding this series of amps. I was not aware that the A-M7 existed. It appears that the controls on our amps are the same, as are the speaker outputs. The layout of the main PCBs is similar. The A-M9 also has an STK module which, I believe, has something to do with the DC Servo. I like the traditional heat sink in your amp.

I don't know whether you would be interested, but I found a Service Manual for your amp on eBay (no affiliation with the seller). I prefer this type of paper, original manual. The cost for it, though, is half-again what you paid for your units. link to SM It may be possible to find a Service Manual in .pdf form for free (or less than $5) searching online.
 
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these are the very first model Diamond back from the 80's I believe
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those and the mark II versions were the best versions of the Diamond imho.

The later versions were good but lost some of the energy and 'fun' sound of the originals.
If you like the diamonds..keep your eyes peeled for a pair of the later 504's...similar magic formula but with an excellent tweeter taken straight from their high end speakers and an upgraded mid bass unit. All in a very attractive miniature package.
 
I was given one of these Sansui mini combo's A M7 + matching Tuner along with a pair of JBL "Industrial" 8216 AT Bookshelf sized speakers, 6.5 in bass mid driver, with Titanium tweeter. They are Pro built JBL with an interesting switch for the cross over. It has positions 8ohm and the rest of the selector switch indicates various settings for Wattage? ie 2 4 6 8 up to 12 Watts? Cant find much of any info on either of these units on line. In any case, highly impressed with the sound quality of the A M7. Is it close to earlier model Sansui ? Of course not, but what major Maker was close to their 70's products in 1983 ? Anyone commenting down their nose is failing to take into consideration, it is what it is. Its not something else. I think this was Sansui's attempt to enter the "Mini System" market, Akai, Technics, Aiwa, and a few others miniaturized into compact profile bookshelf systems for smaller spaces. I have had a few of these mini systems, all have them have not failed to impress me in terms of sound quality and reliability. Some of these units are actually a few of the best built systems I have had the pleasure to own and enjoy. Anyways, anyone out there who finds units like this of interest, appealing or whatever is good, go for it. You will be amazed at the quality sound that comes out of these mini system units, Sansui A M7 included.
 
It's a shame that the pics of the A-M7 have disappeared. I have one that I use at my desk to plug into my laptop (connected to a pair of Wharfedale Delta 30.2 bookshelf speakers) and wanted to see if it's the same. Nice sounding little amp for the light duty I throw its way although the volume pots are getting a bit 'scratchy'.
 
I have an issue with my AM-7 now. It's been fine for years and so I had to go and throw a spanner in the works! Well, not a literal spanner, instead I plugged some headphones into it to test them. Now the amp's got distortion, sort of crackly... I've sprayed some contact cleaner into the headphone socket (it's a PCB-mounted sealed plastic box) and pushed the 6.5mm headphone jack in and out a few times but it still distorts. Does anyone think it could be electrical in any way (other than dirty contacts in the socket)? I guess the next step is to jumper out the headphone socket to test that theory. Trouble is it's a tightly-packed little amp and I'll have to take the front off as well as a few other bits. Oh and I'll have to move a heap of junk off my bench to make space to work on it. :-/
 
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