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have experience listening to 300b set amps
and 845 set amps.
but have never had occasion to listen to 300b
parallel set amp. is the 300b sound preserved?
I reckon the 300B sound would be preserved... but what 300B sound?
My current opinion is that paralleling tubes forces compromises. If a given design already has most of these compromises - and many (most?) do - then paralleling can give the impression of effortlessness and body.
I'd rather avoid the compromises in the first place, but...
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
If done well parallel 300Bs can sound mighty: witness Earle Weston's Artisan 300B from Australia (link below to more pics). It has the clarity and sweetness of the Luxman MB300 monoblocks (with which I am also very familiar) but more grip and power (obviously).
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.
I have listened to the SE300b and the PSE300b from Tempo Electric ( they both use the same driver stage ). the PSE has a more powerful and fuller sound.
Remember that doubling the output power from 7 to 14 watts results in a fairly small increase in apparent loudness from the speaker. You will be spending a lot of $$$ for little output benefit.
With parallel 300b amps, the Single Ended Output Transformer has to be wound to allow for double the current which greatly increases the cost and usually lowers the bandwidth performance.
If you want more power and DHT sound, Push Pull 300b (or 2A3) is how I roll. I have built a 2A3 PP amp that I often prefer to 300b SET.
Big power from SET is more fun with big transmitter tubes. You are not expecting them to sound like 45/2A3/300b types.
thanks for reply
i run audion 845 monoblocks thru dunleavy 4sc (92dB)
and a 300b amp thru swans alure speakers ( also about 92dB sens)
300b sounds great thru swans but while i can imagine the 300b sound,
the overall effect thru the dunleavy's is "muted". i wonder if even 14
watts would be enough.
have limited experience with 2A3 amp. remember extraordinary "openness"
but not the "fullness" in the sound of the 300b
It largely depends on the quality of the transformers and the designers and the parts quality elsewhere.
I am fortunate that the Audio Note dealer in Hong Kong is the biggest of this brand in the world so you can hear the same amps with the same parts quality in both regular and parallel.
So the Quest is a 9 watt 300b monoblock and the Conquest is a parallel 300B and they have a single tube 2A3 mononoblock and the Empress 2A3 parallel monoblocks. And they have stereo power amplifier (one box) versions of both. And the prices are about the same for each same type amp (300b vs 2A3) and very likely using the same parts in terms of chassis, wiring, caps, resisters and transformers. So unlike comparing one brand that simply may be much better than another - here you can compare the same level of competency in design and the same level of parts.
The fact that any given 300B from a good designer beats an incompetently designed 2A3 maker - may give people the idea 2a3 is worse when no it may be that the latter is just a lousy amplifier.
Comparing apples to apples makes more sense.
The 2A3 parallel from AN has big bass and body and sounds FAR more powerful and textured than the same maker's 300B. It's not close. The Empress reminds me of listening to the Jinro 211 or my now sold LM 219IA (845) - huge balls, big sound. But it is more upfront. The 300B is tender and sweet. What you like will depend o what you listen to. I prefer the Empress because it will play all my recordings from sweet to trance/house. The 300B (and AN's 300B is far more powerful than most 300B amps I've heard) is classier perhaps but less full bodied. A veteran audiophile noted that when I am 60 I may come full circle and prefer the 300B. I think there may be something to this.
I just find parallel seems to grip better - not so much about power but about control.
If you have the Empress, I can highly recommend updating some of the electrolytics (like the cathode bypass cap) with the newest Kaisei model; the same goes for the new silver, non-magnetic resistors. I have worked with 2 mfrs (AN and Donald North Audio) to do this and these have significant impact on sound quality. On my Conqueror Silver, the bass was substantially improved. Yes the 300B can "snap". Other "things" also sound better, as a whole - more like the Conquest. I haven't tried this with my Fi 2A3/45 monos, and don't now if I will. I trust Don's choices a lot.
I don't have the Empress - That is well down the line. I have to do a preamp first. I will attend the California Audio Show and try to hear some different preamps. The M6 is my front runner but Jack Roberts on our staff prefers Emia over AN and Shindo. Given how affordable the Emia is I want to hear it and see how it is. Passive preamps generally do nothing for me even if they're more "neutral."
I've sold my 219IA and will soon buy my current review sample: The $825 (incl shipping) KingKo KA-101. A 12 watt EL84 Push Pull (I know but...) integrated/headphone amp that can also serve as a power amp.
thanks for this opinion.
my original post was occasioned by the wish to know whether
a parallel SET 300b amp might be able drive dunleavy 4sc speakers.
(i have a 2A3 X amp and will try again with klipsch la scala speakers
which i haven't listened to in years)
but i am very interested to know who and where that hong kong dealer
is. i will be visiting HK in Oct and mean to go to some audio shops.
online i can only find high end dealers of western gear. will be looking to hear some chinese stuff. i know the controversy about quality on
these forums but i have had two dared amps for about 10 years with
good results. the 300b finally gave out recently and that's why i
was looking again for possible replacement.
if you are reluctant to reply on message board an email would be good
There is nothing wrong with some Chinese amps and there is a lot wrong with other Chinese amps. It just depends on what you are looking at. I know a dealer here who sells amps from China, the US, Europe and Japan - and over the last 5 years the amps with the MOST problems have come from both Japan and the US. Both VERY VERY big name brands - noisy transformers - cold solders, hiss, hums and the sort. Meanwhile they have sold 3 times as many Chinese amplifiers and have had way less returned! So I would not put too much stock into "some guy" on an audio forum who is "guessing" about stuff that he's never heard or used.
This doesn't mean they won't have issue - Bentley has issues, Rolex has issues. So it goes.
A big 22 story or so building with floor upon floor of audio gear is at this address:
Grancastle Commercial Centre, 2T Sai Yeung Choi Street, Mongkok, Kowloon, Hong Kong. I think you have to leave through exit C of the Mongkok MTR but I am not 100%.
Keep this address someplace. It's a little tricky to find because HK is a very busy city and the entrance is not all that big.
There are several other buildings selling gear along with tubes. These shops sell level zero and one Audio Note. The big AN dealer is in Wanchai in the heart of the red light district on Lockhart road.
Audio Note is at
3/F, Beverly House, 93-107 Lockhart Road, Wanchai, Hong Kong.
i will be within walking distance in wan chai
and will probably be at langham place again also
You will get even less power with 2A3 tubes vs 300b tubes
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