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2A3 vs. 845

Here's a message I posted on AA. I'm going to post it here as well for a larger audience.

What a stupid title for a thread, eh? :-}

I'd read a number of times comments such as "the larger triodes just don't have the magic of the smaller 45s, 2A3s, etc". I never quite understood how/why that should be and largely wrote it off as probably either largely untrue or insignificant.

But I made a discovery recently. I have a pair of 845 SET monoblocks and a small 2A3 integrated that retails for about 1/5th the price, both from the same maker, and the 2A3 sounds better on sensitive speakers. It just sounds more open and effortless - it does microdynamics better - those subtle fluctations in voice and horns that make music sound so alive.

Why would or should this be? I *think* the smaller amp has only one gain stage vs two (it shares a single dual-triode driver for both channels) and that could certainly make a difference. And of course, yes, I am not comparing apples-apples here in a lot of ways.

So, in general, what is there about big vs. lil tubes that could or should make the latter preferable? Simplicity of the circuit? What else? How about the power supply. When you've got a giant triode, even a just-adequate power supply is very big and heavy. With a 3W amp, it's *much* more feasible to do a seriously overbuilt power supply. Indeed, going by how long each amp continues to play with the power shut off, and their consumptions, the 2A3 amp wins that one by a wide margin.

What else is there? If anything? Comments are very welcome!
paulfolbrecht
3 responses Add your response
audiofeil
4,011 posts
 
There's more to it that simply the output tube. Circuit design, parts quality, transformers, power supplies, etc. etc. are far more important than the output tube itself. Not to mention the speaker load and other system components.

I've heard good and bad examples of both 2A3 and 845 amps.

If you had the opportunity to hear a 2A3 and 845 side by from the same manufacturer with speakers capable of being driven by each, then conclusions regarding sonic characteristics of the 2 tubes might be more appropriate.

A 2A3 amp with the proper speaker is a glorious experience.
coolhand
58 posts
 
Well put, but most certainly I put it down principally to circuit design and implementation, I've heard a very expensive 300b amp sound like mush and on the same system another apparently lesser 300b amp have such an incisive fast and honed presentation. I auditioned at length the Consonance Cyber 845's and was very charmed by their lushness, but figured that I may not endure all that cholesterol over the long haul, but smitten I was, so I continued my search for other 845 amps and have found a pair with many similar attributes but less lag and a greater degree of microdynamic resolution...Which may well be largely contributed to its more robust power supply but then again it uses a very different topology so again I think one cannot solely judge a tubes character outside of the circuit it resides in.
sns
3,203 posts
 
Yes, I would agree you are not comparing apples to apples here. Way too many variables make a valid comparison very difficult. I've owned $1500 monoblock 2a3 amps and am presently running an $8k 845 stereo amp, no comparison, each does completely different things. In my setup the 845 amp sounds more life-like, performers are much more full bodied and life sized, also increased dynamics, both macro and micro, just a way different presentation. I will give the 2a3 kudos on voices, a little more of that 'lit within' thing, also the 2a3 is a little smoother through the midrange.
Of course, the speakers used in any particular setup matter greatly here, this may in large part make up our quite different takes on these tubes. Specifically, I am able to use a speaker (less efficient) I much prefer with my 845 amp.
I suspect your preference for the 2a3 has a lot to do with speaker choice, the different power supplies and circuitry are sure to affect your preference as well.
As usual, synergy is the key, I happen to like apples, you like oranges. Perhaps in a different setup I would prefer oranges, I just don't think its practical to make a case that one tube is superior to the other.
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