Yamaha A-1

I know I've posted something about this elsewhere, but in 1978 I walked into my local audio store and the owner (sadly, now deceased) knew I was an admirer of Yamaha's amps (I owned a CA-810 at the time…and STILL have it), he was just cueing up an album and I saw this black amp with 3 square colored lights and a volume control, he turned the volume up to the mid-point, selected the DISC switch and let the dampened needle drop (playing into ADS L-910s on their stands). He said "…have a listen to this, I think you'll like it…". It was a sonic revelation to me, and although my then-college bank account wouldn't permit purchasing that Yamaha A-1 amp and speaker combination, I hoped that one day I would.

I took a copy of the A-1/T-1 sales literature (still have that too), and 30 years later I was able to finally acquire that combination. AKer Echowars did some excellent restoration and replacement work in the amp and it sings sweetly today. I really like the external design simplicity, but inside it can be a rather temperamental amp at times with some near unobtainium components (so I've kept some spare donor units in stock, just in case!).

It's quite an amp.
 
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I'm looking for a replacement potentiometer, with ALPS RK27112 50k or even better Alps RK40(perfect fit)
what type do I need linear or log.?
 
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An A-1 was the very first vintage Yamaha amp I ever owned, thanks to a tip from a member here. Though after all these years I forget who it was that tipped me to it.
I still have it, btw. But it is in storage now. Bumped from the starting line-up by the acquisition of an M-4/C-4 combo.

I may have to put the A-1 back into the rotation, soon.
 
Mate ! for sure -- get the A-1 out and see how it goes!! Be interesting to read your impressions regarding comapro with the M-4...I've had the M-4 -- bloody nice amp also!! .....
 
Mate ! for sure -- get the A-1 out and see how it goes!! Be interesting to read your impressions regarding comapro with the M-4...I've had the M-4 -- bloody nice amp also!! .....

I did run them side by side for a while, when I first got the M-4 and IMHO the M-4/C-4 combo edged out the A-1 into the closet, but it was a pretty close race. Perhaps I should try it again, soon. :music:
As recall, the M-4 was just more of everything that was already really good about A-1. The A-1 was no slouch, but it was just a tad bit too reserved vs the M-4.
 
are the transformers in parallel or is it just one transformer per rail? i don't have the schematic in front of me right now.
 
A1 is really beautiful in silver version ! :thmbsp:

Yeah ! How/where did you get that one ??? :smoke:

Regarding the dual power transformers, looking at the schematic, not all secondary windings are in plain parallel mode. For the power to the output stage, the transformers are rather in serial mode feeding a single bridge rectifier, being it that each transformer takes one power rail, so to speak.

The 'compact' (i.e. flat) unit design probably forced Yamaha designers to opt for two transformers to obtain the reduced transformer height while obtaining the desired power and current ratings.

A toroid wouldn't have fit in so well, leaving too little and odd spacing inside the unit, while R-core transformers were only exploited by Philips in the 70's (and wasn't really a Japanese thing at the time).

Hence, two 'square shape' transformers solved the spacing and power rating challenges, IMO.

The downside of two transformers in parallel is more parasitic coupling capacitance with the big bad outer grid.

Not to mention higher manufacturing costs for each unit.
 
i just bought one for a little over 200 bucks. i am a little worried that i chose a difficult one for my 1st restoration project but it was a love at first sight kind of thing.
 
i am a little worried that i chose a difficult one for my 1st restoration project but it was a love at first sight kind of thing.
I've got 3 in the shed waiting. Eaxch time I open one up the eyes roll and I close it again. More difficult than the CA-1000.
Get yourself a NAD 3020, 3140, 3150,,, if you have no diy skills and practice on them. The CA-1010 or 2010 would be good
preparation however probably outside budget $$$$
 
i just bought one for a little over 200 bucks. i am a little worried that i chose a difficult one for my 1st restoration project but it was a love at first sight kind of thing.
Does it work ? :biggrin:
 
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