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In Reply to: RE: recommendations for an SET integrated amp posted by double28 on April 27, 2017 at 12:06:16
I've had mine for 14 years and I can sell it for more than I paid for it new. I've only needed to replace one preamp tube in that time.
But it's not a true SET - it is Single Ended Parallel which is as close as it gets. It takes out plenty of SET amps - I much preferred it to a Cary 300B back in the day and I actually like it more than the Meishu.
The EL84 outputs are also some of the least expensive and the longest lasting tubes available making it really cheap to operate.
Another nice thing is that no AN amp needs to be biased. Making it dead simple for tube newbies.
With regards to SET amps - I don't know the technical reason why but I always greatly prefer Parallel Single Ended tube amps. 300B or 2a3 in parallel sounds bigger and more powerful and more controlled. But more expensive.
Follow Ups:
RGA ;
I see that you are a reviewer , can you speak to the differences between a single and a parallel circuit . Basically what is gained and lost sonically ?
Thank you .
I made an error - I meant Single Ended Pentode with regards to the OTO. It basically just gives the OTO more power - as there is no comparison to a lower power version - I can't make a comparison.
With parallel (two tubes) versus (one) it is basically doubling the power. The pitfalls mentioned below I suspect depend largely on who is doing the designing and how good they are at avoiding pitfalls.
Parallel versions over more power (double?) and seem to add some more stability and control of bass drivers. For instance I am not much of a fan of the 300B as I find them quite weak willed (Hong Kong dealer calls them "lady amps") which implies they are nice for singer at a piano kind of stuff but fall apart on demanding material - the parallel 300b IME does not.
This is very true of the Empress 2A3 which actually bowled me over with its seemingly bottomless pit of power bass and drive. When I was playing Split the Atom with pelting trance bass lines - I had to shake my head that this was 7-8 watts on relatively modest sensitivity speakers.
The one tube stereo amp version (name escapes me) couldn't really do it (though it might on 100dB sensitive speakers. I didn't hear any sonic advantages with the single tube versions. Whether there is with other brands I can't say.
But I think AN probably does SET amplifiers as good as SET amplifiers can be done and because they make so many amps - you can actually audition 1 and 2 tube versions of the same amp. Single 300B, Parallel 300b, Single 2a3, parallel 2A3 and I believe also 45.
You really have to decide. I really like the AN Empress - to me it's the best value for the dollar amplifier that Audio Note makes. But I also know others who greatly prefer the 211 or 45. So it goes.
91derlust ;
You wrote..."Paralleled tubes produce greater power and simplify transformer winding somewhat. They are also harder to drive (increased Miller C), place more demands on power supply and cathode bypass design (larger C required for equivalent performance). Moreover, they introduce the variable of trying to match the two tubes as they age - no two tubes perfectly match and that situation is likely to worsen with age."
Can you explain why the paralleled tubes , aging at different rates , would affect the final output ?
Thank you .
Audio Note amplifiers all autobias. I have not heard anyone say there were any of these problems with any Audio Note amplifiers. Can't speak to lesser designs using lesser quality parts.
You may want to direct the question at 91derlust or indeed send an e-mail to Audio Note asking them about tube drift in a parallel designs to see if this is an area of weakness.
What Frihed89 said below.Paralleled tubes produce greater power and simplify transformer winding somewhat. They are also harder to drive (increased Miller C), place more demands on power supply and cathode bypass design (larger C required for equivalent performance). Moreover, they introduce the variable of trying to match the two tubes as they age - no two tubes perfectly match and that situation is likely to worsen with age.
What does this mean in a practical sense? My current thoughts are:
Traditional (old school?) amplifier designs with lots of electrolytic final PS capacitance, lots of cathode bypass capacitance, and slow-recovery power supplies would likely benefit from paralleling output tubes. The paraelling is easily implemented and additional power can mitigate some issues and the trade-offs are probably not evident. The advantages outweigh the disadvantages. Using these types of amplifies used with moderate efficiency speakers running mid-QTS drivers and soft dome tweeters, is a successful paradigm for off-the-shelf, (relatively) broad-appeal systems. They have that classic SET sound.
Paralleling output tubes in amplifier designs where power supply and cathode bypass capacitance is carefully calculated, higher quality capacitance is used, and power supplies have quick, well-damped recovery, is probably a different story. The cost of paralleling would be much greater (as would the space required) and it would impose power supply compromises. The additional power provides greater achievable volume, but I can see how paralleling would introduce sonic compromises in this type of design. For high(ish) efficiency speakers running low QTS bass and resolving compression/ AMT/ quality ribbon drivers, I'd prefer a well-designed single output tube SET.
I imagine that it is a case of horses for courses.
Sorry for the off-topic, but that is the way I see it at present.
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
Edits: 04/28/17 04/28/17 04/28/17
that without some (all? more?) of the modifications you mentioned, dynamics in time and amplitude are impaired.
In many commercial designs, even with a single tube output, the dynamics are already impaired due to the PS design and component selection. Paralleling, even with only minor changes, would likely improve the subjective performance.
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
My two cents...paralleled output tubes just gives you more power. Many SE and SET amps parallel the output tubes to do this (2 tubes per channel). It is still single ended. Both tubes in parallel conduct identically through the full wave cycle.
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