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Yes, the parallel 300b and 2a3 amps I heard do retain the sonic characteristics of their output tubes. But, there are those who don't like parallel output tubes because, they claim, the sound is not as pure and clear as when only one tube is utilized.
I spoke with a designer who claims that it is very difficult to implement parallel output; even when the tubes are carefully matched at the outset, they quickly become unmatched, with one tube being much stronger and doing most of the work (hence, the output is not much different from running a single tube).
With my own parallel 2a3 amp (Audio Note (uk) Kageki), I have indeed found that the tubes do become unbalanced, with one measuring weaker than the other, but, the amp sounds good and I don't push them very hard so I don't need the extra power.
In pursuit of the best I could build many years ago I designed an 845 SET and was so impressed with it's sound against all I'd previously built or heard that it became the prototype of my still current Parallel 845 monos using essentially the same circuit but with better PSU. The result was better in almost every respect.
I do not subscribe to the theory of a single OP tube design having advantages over PSE and IME smearing is a theoretical myth. Sure, the tubes must be well matched and they can indeed creep out of balance over time but this can be mostly mitigated through careful design.
I posted a Spice analysis a long time ago actually backing the theory that relatively small tube imbalances can cause current hogging and this led me to pay closer attention to balance. I can attest that in almost 15 years of running these amps I've not experienced anything that would change my mind over the advantages of PSE outweighing the disadvantages, starting with lower OP impedance and additional headroom, which ultimately reduces distortion.
Whilst I chose 845s, I also experimented with 45s, 2A3s, 300Bs and 211s (mostly out of curiosity) and the result was more or less the same.
My 2C FWIW, and all that:)
I have never noticed this in my various parallel SET 2A3 amps and suspect it may be due to both the degree of matching of the tubes and how each tube ages.
"With my own parallel 2a3 amp (Audio Note (uk) Kageki), I have indeed found that the tubes do become unbalanced, with one measuring weaker than the other, but, the amp sounds good and I don't push them very hard so I don't need the extra power."
so, are you tempted ( as RGA has suggested) to switch tube
positions and let us know if you hear any significant difference?
I knew that could happen in theory, but i think that this is the first time I have ever read about such an experience, esp. on an AN(UK) amp. All of my 2A3 and 45 amps have just a single output tube.
I do have a pair of Class A triode-wired PP mono amps. Of course PP will always need 2 tubes per channel. But both monos have a balance pot. I wonder if that would work in the case of parallel SET to even out the balance?
Could you not just flip the tubes every three months from left to right and right to left to even out the wear?
No, the stronger tube will always "current hog" regardless of position.
Have Fun and Enjoy the Music
"Still Working the Problem"
This assumes that it is actually a real effect. So far the 'current hog' stories have not quite been what I'd call air tight.
For the usual A1 cap coupling, the grid circuit gets to be a significant load, especially if you try to make a 10W amp out of 45's.
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
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