Yamaha A-1000 integrated amp Class A

iwander

Member
I recently aquired an A-1000 amp with auto Class A.

I have been interested in trying Class A amps but have been too expensive. There's been alot of buzz on Class A lately so I thought of jumping in.

After cleaning it up with deoxit, I hooked it up to my Cornwalls for a listen. In class AB mode, it sounded great. It sounded close to the Nakamichi SR-4A I had there. I then switched it to class A mode. I could not tell a difference from AB mode. I listened at different volume settings. Still sounded the same.
I thought class A was supposed to be more open and detailed. Perhaps I got a worn out unit. It definitely heated up more in class A mode. I like the sound of the amp but wasn't an improvement in class A mode. Perhaps CA-1000 would be better.


Was I caught up in the hype of Class A amps? Is the magic only on tube units? I like the A-1000 enough to keep it.

Was my expectations of Class A SS amps too ambitious? I want to give Class A another try. Perhaps I should save up the cash for a First Watt amp instead.

Looking for any thoughts or opinions.

Thanks
 
Many have reported hearing no difference between A and AB on various Yamaha integrateds. I thought my CA-1010 and CA-800 sounded a little better in A.

There might be an expectations issue at work also. The Yamahas are great amps, in whatever class you run them, but they will not magically become a Classé DR-2 when run in class A. Not all class A amps are equal just like all rear drive sports cars with independent suspension are not the same. There are many design and construction details that make a difference in both cases. Some class AB amps are clearly better than some class A ones. Life is not usually completely cut and dry.
 
A CA-800 running in full on Class A bias sounds a bit more neutral and noticeably more transparent than AB to my ears. Interestingly, I think I was still using my Cornies (now long gone) when I was playing with the CA-800.

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There are some very fine sounding Class A solid state amplifiers. Some of the early (real) Mark Levinson amps come to mind.

Cannot vouch for an A-1000. No experience with it. Is it "real", full-on Class A bias? I just don't know (I'll go do some digging). How well it performs under any operating conditions at this late date will depend strongly on the condition of all of its passive components (resistors, capacitors, chokes) and also - possibly - actives (transistors, diodes, and other silicon devices).
 
I couldn't hear much difference between Class A and AB on my A-1000. With B&W DM220 speakers, a Technics MASH CD and a Technics SL-1200MK2 TT. Various CD's and records.

It does sound fantastic to my ears in either mode and is my main amp.
 
Class A is not "more open and detailed", it simply has less distortion (well, it should - doesn't have to). If you can detect it or not depends entirely on your speakers.
 
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Thanks for the feedback.

It would seem my expectations were a bit colored. To test sound systems, I burned a CD with several tracks that have certain things I'm looking for. Typically each track will have a specific feature to look for. Features such as soundstage separation and depth, sound dynamics, vocals, etc. All tracks are music that I'm familiar with. Listening for the specifics of each track allows me a better chance of evaluating the system I'm listening to. I know what to listen for in each track. One track will not show everything in the system. It works for me. Finding a stereo store is hard nowadays. They are all doing home theater sound systems. It's what keeps them in business. Does anyone know of any stores in the LA area that have Class A amps to listen to.

Thanks again
 
Is Yamaha class A true class A as in Nelson Pass designs, I thought I read somewhere it's a quasi class A?

Or it may be my Alzheimer's again. :D

I had a CA-800 years ago and my speakers were not good enough so you could tell the difference.
 
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Old thread but one where I have some experience. I had an A-1000 and I found there was a very distinct audible difference between A and AB. I much preferred A. I was driving a single pair of Magnepan MG-1s with it. I loved it. If I hadn't been dusting the cabinet one day and allowed a paper clip to slip out of my shirt pocket to fall right through that fine grill to the top of those four big caps causing great sparks, I'd doubtless still have it and not the multiple MX-1000s I have now. It was a fine amp, especially in the A mode. I definitely could hear more "detail" in Class A, if detail includes "texture" of sound. Class A more accurately depicted the original sound source. While still clear, the AB mode distortion, as low as it was, and it was, *did* mask some of that finest detail that goes into the texture of something like the smoke of a flute, for example.
 
I've just started using the same Yamaha A-1000, and in my experience, the difference is *very* slight, but there. The bass has a bit more presence in Class A, sometimes (and only when I'm in Source Direct mode). Just my 2 cents!
 
Before we poo poo a "Class A" amp, or any other amp for that matter we should ask about the general health and well being
of these 30-40 year old amps. Have they been refurbished and the bias correctly set. I've just finished 2 CA-1000 rebuilds
(after 2 CA-800's). The 800 is a good amp, the 1000 is better. Put me down for a subtle but definite difference/improvement
in class A in each case. Next, the 1010...
 
The soundstage (width/depth) is the biggest thing that improves in Class-A mode, but the difference is most pronounced with a speaker (particularly tweeter) that is capable of actually conveying the improvement. Small but certainly noticeable!

I agree with mbz in that refurbishing and adjustment is important too. The internal parts cop a thermal workout when in Class-A, so a full re-cap with high quality parts is a must if you want the best performance from that 34 year old beast.

The A-1000 is a sonically beautiful amp, enjoy.
 
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