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Yamaha A-700

G

giovanni

Active Member
Just picked up a Yamaha A-700 for cheap. Physically not in the greatest of appearance but seems to work fine. Heavy unit and sounds good too.
I have done a search but cannot find much info on this thing. Does anyone know the power rating (RMS)? How good were these units. Looks to me like its is from the late 80's.

Thanks.
 
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Well, the manual's not listed on the Yamaha site :-( You probably already knew that!

This may not help at all, but there was a thread on the (possibly) similar A-760 at AA fairly recently: http://db.audioasylum.com/cgi/m.mpl?forum=vintage&n=109183&highlight=mhardy6647&r=&session=

EDIT: ooh, I found a picture of one!
Yamaha%20A-700.jpg


BTW, the honcho at "the Vintage Knob", Axel, shows up here frequently, so he may weigh in with his knowledge on this amp.
 
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That is it exactly!!!
But I am not quite sure if the A-760 is close to it.

Any idea what the buttons labelled "Auto class A" and "Direct" are for??
 
I think the "Direct" is for the phono preamp and bypasses the tone-control amps, etc. My CA-610II has something similar called "Main Direct" but leaves the function selector in-line.

I would guess that "Auto Class A" controls when/whether the (power) amp runs in Class A at low power levels. Many of the earlier Yamaha amps (e.g., CA-1010) had switchable 'all Class A" operating points.

Take a look at some of the Yamaha pages at www.thevintageknob.org
 
Orion lists an A-700B as having 105 wpc and from the later 80s.
The A-760 is listed as having 80 wpc.
 
I bought an A-700 (new) back in 1986, and kept it until 2000. As you can tell, I was very happy with it. I replaced it with a Technics SA-800 reciever that I'd always lusted after, but ultimately didn't sound nearly as good or as "tight" as the Yammie. I got my hands on another A-700 about a year later, but financial considerations forced me to sell it a couple years ago. I would love to get another, but they don't seem to show up for sale that often, and when they do they're often pretty beat up.

My only complaint about it is the rather cheesy-feeling source selection switches. Other than that, it was typical Yamaha high quality. The sound was also awesome...I could listen for hours and never grow tire of it.

I have a .pdf of the brochure and owner's manual. PM me for the links.

BTW...it was rated at 100 WPC (0.005% THD) into 8 ohms and 120WPC (@0.007% THD) into 6 ohms, 20-20k Hz
 
A-700 Was Possibly One of Yamahas best amplifiers. The only drawback being its looks really. 100 watts per channel at .005% you say? and with 110db snr ratio, hmmm. Nope cant see anything on offer retail under the sun with matching specs.
 
I got an A700 that I really love.Mine is flat black.Very good pre-amp section and very crisp output.I have never seen any manuals.I'm considering an A1000 for bi-amping.
 
Yamaha A 700

After reading all the great reviews of the Yamaha A 700 in AK, I searched and found one. In my opinion, unlike some others who have commented here, this is one among the best looking vintage amps I have owned ( I have a silver one) Everyone who comes home is flattered by the looks first.....
I have connected it to a Marantz cd 5400 and JBL TLX320 floor standers (unfortunately the speakers are of 4 ohms and A 700 impedence range is starting from 6 ohms.) The sound is very clean compared to the Technics and Pioneer amps I have. My Pioneer has more punchy bass than the Yamaha, but the Yamaha sounds more like a high end amp. The sound quality is astonishing, and the sound is not at all tiring. I can listen to music for hours without getting irritated as with my Technics. Im so glad I got one of these.
 
The A-700 is around 100 wpc. It has 22,000 uF x2 main filters. Mine was a junker so pulled them out and fitted them to a vintage Rotel.
 
Great to see others who have an A700.
Mine has been in the family since it was new. It's all original. The only problems have been dirty pots and switches. About two years ago I did a quick treatment with deoxit and that only lasted about 6 months. So I took apart the front panel and deoxit dn5, let things dry out for a few days and then used deoxit fader lube. All controls are fine since.
Heres one thing to check for. That brown assembly glue the electronics manufactures use for gluing parts to the board before the soldering process. I was getting this "popping" noise from the speakers. If I tapped on the case I'd get a scratchy noise out of the speaker too.
After so investigative work, I found that a jumper in the middle of the board basically had a intermittent "make, break" situation from being corroded by this glue. (Yes this glue becomes corrosive and conductive as it ages).

Took care of that problem and the amps still runs great, still has it original caps, all Nichicon Muse series.

I was thinking of recapping it untill I found out how much all those caps would cost, including those big power caps.
 
I forgot to mention:
I don't really think I can hear any difference in class A and because of the age of the unit and the fact that it runs much hotter in A, I don't use it in that mode.
 
Digging up an old thread here, but I figure its better than starting an identical thread and clogging up search results.

I have a A-700, currently awaiting a complete recapping. Just curious if Yamaha used a special thermal compound on the transistors, or if removing the old dried up stuff and putting on decent CPU compound is a good thing or a complete no-no. I was thinking that part of the heat problem with these in "auto class A" wasn't normal heat from higher bias, but to some degree (no pun intended) due to inefficient transfer of that heat to the heatsink.

If it's possible or advisable to replace it, these things might run a few degrees cooler and last longer. they are excellent amps.
 
I'm not terribly knowledgeable, but based on my experience with my A-700 I'd say replace the stuff. I had mine in for repair because it kept going into thermal shutdown (if you do indeed have inefficient heat transfer that's what will happen), and I think this is one of the things the repair shop did to correct the problem. It works fine now and runs cool (though as in a previous post, I don't use the auto class A mode because I just can't hear a difference).

When you get the recapping done, do post and describe the results! I'd be interested to hear, for I've considered doing the same to mine.
 
austi15 said:
digging up an old thread here, but i figure its better than starting an identical thread and clogging up search results.

i have a a-700, currently awaiting a complete recapping. just curious if yamaha used a special thermal compound on the transistors, or if removing the old dried up stuff and putting on decent cpu compound is a good thing or a complete no-no. I was thinking that part of the heat problem with these in "auto class a" wasn't normal heat from higher bias, but to some degree (no pun intended) due to inefficient transfer of that heat to the heatsink.

If it's possible or advisable to replace it, these things might run a few degrees cooler and last longer. They are excellent amps.
Click to expand...

+1

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Coincidentally I got a surge, the fuse was overrated and it caught on fire a few months later. Just picked up another one and it sounds excellent driving my power hungry L7s
 
Im reviving this old thread in hopes to find an answer to my problem. First time poster... well, I just found this site today haha. I have a Yamaha A-700 amplifier that is in pretty much dead mint condition. My father bought it around 83 I would say, right before I was born, and took very good care of it. It has never had any issues nor has it ever been repaired. Flash forward to 2007 when he was moving and said you can take it or I am going to get rid of it so of course I took it. I have had it ever since and tried to take equally good care of it. I use it with a matching Yamaha tape deck (cant remember the model) and an Audio Technica ATLP-120. Previously I used a Dual 1226 but it kept having issues so I opted for something newer. Setup worked great until last weekend when I went to play a record and it just started cutting in and out. I tried switching to the tape deck and it worked fine. Later that night when I was able to get around to looking at it I started switching cables around to see what would work. I tried putting an aux cable in the phono section and plugging it into my phone and it did the same intermittent type stuff. Switched it back to aux inputs and it was fine. So when the sound comes and goes there is an internal click noise coming from the amp... like its switching off the phono channel itself. Does anyone have any clue what this may be or how I can fix it? Since I moved a year ago we acquired a cat that likes to lay on top of it when its turned off... could it be cat hair? hahaha. Surely its something more electronic? Any help would be greatly appreciated cause I know very little about these things!
 
I have a chance to get a seemingly mint, untouched (according to owner) Yamaha A-700 which is supposed to sound great. The exterior really is mint, however I wonder what would you think of interior!? Has anything been done there? Anything looking of or in need of repair?




This is a different device for comparison (which is supposed to be untouched):
Yamaha_A-700-_R1_H.jpg
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Thanks,
Cheers
 
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