^^ At very low power levels the distortion of the amp is very low- hence that 'inner detail' you hear so much about. As the power increases distortion rises with it. If you are nearfield yous speakers may be efficient enough that you're not getting into trouble with distortion, but usually a 94dB speaker isn't enough.
Unless you're clipping the amp you won't hear outright distortion. At power levels less than clipping distortion imparts a tonality and at levels above about 20% of full power, a sense of 'dynamics' due to higher ordered harmonics present on transients.
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+1 @atmasphere Thanks for your insightful summary. It does seem that the lowly 1.5 watt 45 tube is becoming increasingly popular.
I do have a question for you, though. When you talk about the distortion that SETs have, you also state that if they are listened to below their distortion threshold (not exactly how you put it) they are very linear. Am I correct to understand from your comments that a SET listened to at very low volumes is not distorting? That would explain my experience, which I appreciate is limited... I listen typically in the near field well below 80dB. My speakers are 94dB efficient, so I *think* I'm typically using a fraction of a watt. I know that drum hits and crescendos can require the amp to produce instantaneous peaks far above that... But I don't seem to hear much or any distortion in my system.
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Interesting comment, maybe why so many like the sound of the Elrog 300B which feature the tungsten filament.
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Definitely the "Thoriated Tungsten Filament" family as 211, 811A, 845, GM70.
If you are after impact, clarity, and soundstage more than after a lush sound and coloration there is no escape from these.
Jan
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What do you think about OTL SET amps/integrateds, and the most
desirable triode tube in that instance? (I have a Vinnie Rossi L2iSE). When you eliminate the output transformer, you eliminate with it the reason to have an SET. Its the way the SET makes distortion that makes them interesting to listen to; at low power their distortion is so low as to be unmeasurable- and this is the source of their 'inner detail'. One argument that has been made for the last 30 years is that SETs sound better since there is no 'phase splitter'. That argument is hard to prove out in practice since there are so many variables involved! How many people have heard a push pull amplifier using exactly the same tube complement as their SET?? One thing I can state here is that they certainly won't be able to make that comparison if the amp is transformerless! DHTs have far too high a plate resistance value to be successfully used in an OTL, unless a number are used. We made a 300b-based OTL about 25 years ago that used four 6300b graphite-plate power tubes to make about 7 watts. Four 6AS7Gs (which are indirectly heated triodes) did a better job. Recently and just for fun I've been designing a push-pull ultralinear tube amp that makes 5 watts/channel (ostensibly for my bedroom system, although it would make a good desktop or headphone amp too). Often when SETs are compared to push-pull amps the P-P amp makes a lot more power. I am interested to see what happens when the power levels are the same. |
atmasphere - always enjoy reading your informative posts. What do you think about OTL SET amps/integrateds, and the most desirable triode tube in that instance? (I have a Vinnie Rossi L2iSE).
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What would people say is the best SET for something like the Tannoy 15 HPD - A lot of people say the speaker demands push pull amps but SET is something I always wanted to try for the soundstage. |
300b amp:
Psvane Acme 805
NOS Russia Meltz 1578 in the 6sn7
NOS sylvania vt229 in 6sl7
As I understand it, the 300b tubes have the smallest impact on my particular amp. They’re next (Psvane Acme) at over $1,000 for a pair. I hope they’ll be worth it. |
I also have a Dynaco ST-70, also running the EL34 in ultra linear. I
love the sound of this amp as well but if I listen to the EL34 in SET
triode and then listen to the Dynaco, the Dynaco then sounds very
mushy. Is the Dynaco sorted out properly? Older ST70s will need all the filter capacitors in the power supply replaced and everything spec'ced out to really assess that. |
The el 34 is a good sounding tube but is a pentode and not a (Innately) triode (Although it can be re-wired to triode).
It is 'indirectedly' heated as opposed to 'directly' heated triode (DHT).
I believe that the OP was referencing specifically to the niche of DHT tubes.
Charles |
I have a Decware that runs the EL34, a pentode tube, in triode. The sound is unbelievably sweet and wonderful. With the amp I have the ability to tube roll and tried some KT-88's. The KT-88 totally changed the sound and made it sound too bright, too sterile and the musicality went away. Look forward to trying other tubes to see what, if any, sound better. I also have a Dynaco ST-70, also running the EL34 in ultra linear. I love the sound of this amp as well but if I listen to the EL34 in SET triode and then listen to the Dynaco, the Dynaco then sounds very mushy. Some may disagree but to me it sounds like Polk speakers, which to me are pure nasty.
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Again no clear cut answer. Most desirable to who? One could certainly say the 300b is the most popular DHT tube. There are numerous current production brands (With various price categories to choose from) 300bs available. A sign of demand if nothing else. There are probably more 300b amplifiers produced than with any other DHT tube. As has been pointed out, the vintage/original Western Electric 300b is highly coveted and extraordinarily expensive. So to a certain niche of W.E. tube seekers they are very desirable.
Charles |
Many swear by NOS 300B Western Electrics. But they have become rare and upwards of $5000+ a pair. My favorite are 45s in general the lower the power the more magic. But at 1 1/2 watts you need super sensitive speakers. |
Thanks everyone for these wonderful responses. I feel, 300B got a cult status & many folks are waiting for another batch from Western Electric.
on a side note, I didn’t ask opinion for ‘best’. I’m looking for opinion about desirable tubes. The ‘one’ which everyone is after. It could be for academic purpose. Need not be the best. Again, it doesn’t matter whether it sounds the best in my system. The desirability has nothing to do with it. It’s what the general public ‘wants’ !! |
yep, the best one is the one that sounds the best to you, the best implemented in the amp, the best matched to your speakers, to your room...
asking these questions -- what is the best speaker, what is the best dac, what is the best cable
ugh |
+1 testpilot. Any one of the listed tubes can sound truly excellent if careful attention is given to speaker selection. The higher power transmission output tubes such as 845 and 211 can be magnificent sounding in the hands of a talented/skilled builder.
Same is true of low watt 45,50,2A3 etc tubes. Ultimate results are fully dependant on the designer/builder and quality of the parts utilized. I just do not believe that any one single tube can be declared the absolute best. There are a multitude of factors to be considered.
Charles |
The best sounding SETs are the ones with the least amount of power. This is due entirely to the output transformer- the differences people talk about between the various tubes has more to do with the output transformer than the tubes themselves. Once you get over about 7-8 watts of power it gets extremely difficult to build an output transformer that has full frequency bandwidth- and as a result many have compromised bass response on that account.
So back in 1990 there was a mystique around the 300b; by 2000 the 2A3 had ascended the throne and these days its the type 45.
If you really want to hear what any SET does, that will best be done with a set of loudspeakers that are efficient enough that the amplifier is never asked to make more than about 20-25% of full power. This is to prevent distortion, in particular the higher ordered harmonics, from showing up on the transients present in all music. The ear uses the higher ordered harmonics to sense sound pressure, so when they show up on transients it tends to make the system sound 'dynamic' but its really distortion masquerading as dynamics.
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The most desirable tube is the one that works best with your speakers. |
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Generally, I think the 300B is probably the most popular, and therefore sought after option for a SET. That being said, I personally prefer the 845 in a SET as I love the soundstage it delivers. It also give you a touch more power and has a bit more flexibility than a 300B.
My second preference is the PX25 as it provides a middle ground between the 2A3(ultra detailed) and the 300B(ultra lush). It has a velvety detailed sound that is awesome with Avantgardes.
I don’t know the GC33C or GM70.
Other candidates would be:
45
PX4
T100
EL34
other 300B derivatives
300B XLS
320B XLS
520B
1605
full disclosure, I import a line of SETs and am a dealer for KR and Emission Labs.
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