Opening a can of worms again: Why Tubes sound better
- Thread starter Analogous
- Start date
10-12 watts !li
You have succumbed to the temptation of the “Power Devil”
too !.
Haha, i know! I feel like a sell-out.
If you DIY by yourself, I would be happy to assist / or give you input. It seems to me, you have no speaker selected.
A 300B is a totally unnecessary expense - beatable today, for a variety of reasons.
( Come to think of it, Hari's 2020 tetrode-implemented KT88 DIY amp replaced his 300B amp. Just P.M. and ask him. )
Ideally, you should start with a highly efficient speaker, 100-101 dB or more ( I use 103 dB ) , and then, go from there, ..... as a general path of system-building.
BTW, I can easily advise you on how to transform your existing DIY Loftin-White 2A3 amp, on a step by step basis - and you will KNOW, after each step, you are doing well.
Most assuredly, your Direct Couple's VDC is too low, likely - only about 150 VDC. Certainly, your power supply filter chokes are far too high in DCR. Also,, the B+ filtering to the plate resistor of your input tube - musically demands a much more sophisticated filtering topology. Every published schematic I see, past and present, unacceptably to my listening, underestimates these tube amp parameters. Want to send me your schematic and voltages ??
But what about your speaker ????
Or,...... there exists my 2023 design, the 6005 TRIPLE DC SE amp.
Or, ....... name it..................................... DCed..... KT88, KT150, and the new KT170.
The 6005 Output tube, as I employ it on HFV in 2021 and 2022, presently is easily my favorite sounding output tube, musically. Have not heard all 5 of these suggested amp Finals Tube iterations ( all would be two stage, DCed , SE, zero NFB . )
Jeff
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I have used a 300B before. DHT - especially DC heated sounds bad to my ears. The 300B cannot outperform the 2a3 in sonic attributes. If at all you decide to go the 300B way, then only an WE 300B could make any difference.
Thanks for the replies, gents. A few comments:
1) I dont want to replace my 2A3. I love the sound i get from it, and I plan to retain it. The new project is mainly driven by a desire to get back into amp building after a gap over over 25 years and to try a different topology, perhaps.
2) Speaker-wise: yeah, that's a separate quest altogether (both for my 2A3 and this new amp). I have mentioned earlier that I have sold my Klipschorns. I have access to a friend who can build cabinets for me, if i can settle a good design. Regardless, i want to work on this build anyway,
3) Hari, i am surprised that you found DC-heated 300Bs to sound bad. I've always considered 300Bs to be the de rigueur of SETs: enough power to be practical (unlike 2A3s or 45s) but enough of the SET magic. I am not sold on 300s - if there are other options with more widely available/less $$$ tubes than WEs/Mullards/RCAs, I would certainly prefer that.
4) Jeff - the plate voltage of my 2A3 is around 200V or so, off memory. I picked it to be in the middle of the linear part of the tube curve. The chokes could be too high, as i remember adding more rectification than the original schematic. I need to dig up my own build schematics, which are in storage somewhere. Will message you once i find them.
5) Jeff - also, thank you for the tube suggestions. I have increasingly been seeing KT88s on tube amps of late but mostly PP designs - let me check those and the 6005 for some SE schematics.
1) I dont want to replace my 2A3. I love the sound i get from it, and I plan to retain it. The new project is mainly driven by a desire to get back into amp building after a gap over over 25 years and to try a different topology, perhaps.
2) Speaker-wise: yeah, that's a separate quest altogether (both for my 2A3 and this new amp). I have mentioned earlier that I have sold my Klipschorns. I have access to a friend who can build cabinets for me, if i can settle a good design. Regardless, i want to work on this build anyway,
3) Hari, i am surprised that you found DC-heated 300Bs to sound bad. I've always considered 300Bs to be the de rigueur of SETs: enough power to be practical (unlike 2A3s or 45s) but enough of the SET magic. I am not sold on 300s - if there are other options with more widely available/less $$$ tubes than WEs/Mullards/RCAs, I would certainly prefer that.
4) Jeff - the plate voltage of my 2A3 is around 200V or so, off memory. I picked it to be in the middle of the linear part of the tube curve. The chokes could be too high, as i remember adding more rectification than the original schematic. I need to dig up my own build schematics, which are in storage somewhere. Will message you once i find them.
5) Jeff - also, thank you for the tube suggestions. I have increasingly been seeing KT88s on tube amps of late but mostly PP designs - let me check those and the 6005 for some SE schematics.
Well, I can see you are a independent thinker, and best of all.....serious.
Stay with SE amps !!!!
If 200 VDC is on the plate of your Driver tube ( the Direct Couple ), you are to be very much congratulated !!!
The next question...what is the mu of your Driver tube?
With a mu of 4 2A3, use of a Driver with a mu of 100 gives the very best two-tube combination, listening wise ( jump factor / your FUN factor ). ( 100 Xs 4 =s 400. )
In 2019, I car-transported my first ever KT88 amp ( a 2,500 miles round trip ) to my mentor's home, and four of us ( serious DIYers, one a musician - all very good listeners ) A-B ed amps on my mentor's SOTA system.
YOU might as well gain from what we four guys uniquely determined. No need to repeat other people in audio's common design mistakes.
2A3 Vs 300B. Start with a 100 db speaker, so you can use almost ANY powered tube and use the best performing / sounding Finals tube !!!!! And thus........ build and hear the best-possible sounding amps.
The 300B is chosen by people, over a 2A3, because most people didn't quite get their speaker efficiency right - from their very start !!!
In an optimized highest end ( ie: 100 dB minimum ) audio system, the original harp filament structure 2A3 will readily outperform any and all 300Bs.
Two reasons.
First : AC heating of a 2.5 Volt 2A3 filament sounds better than than ANY type of DC heating. The best builders will know this . DC heating of a DHT "bucks" out some of the music. All 300Bs need to be DC heated ( because it has a 5 Volt filament ) ........twice as high in voltage as a 2A3's filament. With a 2A3, in any good AMP circuit, AC heating at 2.5 VAC sounds superior to DC heating. That is reason number one ....... why a 2A3 is superior.
Second : The second reason why CERTAIN 2A3s are superior is due to filament shape and the filament's electron emission pattern - in relationship to the tube's plate shape. All of the early triode tubes, are inferior because of their filament-to-plate ( non symmetrical ) electron emission patterns. ONLY the first RCA Harp filament structure got that right. All the other early triodes had "M" or "W" shaped filament stringing, which inherently, emitted a non symmetrical flow of electrons to the plate.
The original Harp 2A3 took something like 23 additional welds to build. So, they took a couple cheap to mass build ( for table radios ) Type 45s, paralleled them into a single bottle, and cut production costs. Bi-plates are inferior to a decent monoplate 2A3, to this day. Even so, with a-symmetrical filament structures equally existing in both designs.
So , you like the 2A3. What is THE BEST design for a 2A3 ?? For starters, not a bi-plate, and the filament structure must not be a " hanging M or W " configuration.
ANSWER : It absolutely needs to be a Harp / Monoplate, to have the best possible 2A3 audio playback performance.
Guess what, in modern times, Monoplate / Harp filament structures tubes are available to us now, often at a premium cost. If we were to have to use such a triode, Jac at Emission Labs offers both 2A3s and 300Bs that are Harp and Monoplate. Not only that, they have superior metallurgy and better, thicker glass envelopes with higher vacuums, VS: any of the vintage-made tubes. JJ Electronics in Europe offers their JJ 2A3-40, which is THE best value in a "2A3" existing today.
The EMLs and JJ 2A3-40ss make the vintage tubes look like the poorly designed JUNK that they are.
All the vintage commercial tubes ( not transmitting tubes ) have poor metallurgy. The plates look like they were made out of an old tin can. Don't they? !! The wires, leading down to the tube socket pins, are thin, too thin, and too long. They are prone to lose transfer efficiency. Not so, with today's EML and JJ designs !!! No contest. Anyone who would buy a new version 300B by Western Electric, has made the wrong choice, solely due to the WE's non harp filament structure, VS: Jac's EML 300 B offering.
But lets get back to your liking the sound of a 2A3. ( I have built zero NFB amps with Type 2A3s, 10s, 50s,45s, etc etc. over the last 42 years. ).
When doing our recent amp A-Bing ( in 2019 ) at my mentor's home , we compared that first new KT88 stereo amp, against his $18,750 USD 2A3 monoblocks. His 2A3 amps have under development since 1989 ( SE and DC ). For a Finals tube on the A-B visit, my mentor used VAIC meshplate 2A3s, the first 2A3 meshplate ever produced. It is ultra rare, costing several hundreds of dollars per tube, IF you could ever today find ones that are new or close to new.
My new stereo KT88 amp used $41.00 USD each, 2018 production Electro Harmonix Kt88s. Our circuit topologies were basically similar. ( I will list differences below ).
Guess what, the stereo KT88 amp " easily destroyed " the VAIC 2A3 mono amps, in terms of resolution of the music, and dynamic shading. I did not have my prototype fully bypassed as well as my Mentor's monos, but that was minor compared to what we were hearing overall, and what we would all want to own, and listen to !!!
The stereo KT88 was different as follows :
a) Two EH 5U4GB rectifier tubes, not just one
b) double Shunting ( drawing 10 Xs the current to ground ) of the sensitive spots' B+, two Shunts in series, passively stabilizing and lowering Z, not just once, but twice.
c) double DFFF ( Dennis Fraker Final Filters, L1/C1/L2/C2 ) to the Input tube's plate resistor, instead of a single DFFF.
d) a GTO ( 5uF / 1200 VDC ) capacitor across each of the two main B+ L/C filters leading to the output stage.
e) all internal AC polarity locations selected as ear-optimized. First time ever.
Hari Iyer's year 2020 KT88 build was that 2019 circuit, wherein I adapted to it a lower mu Driver tube.
Jeff's 2021 HFV documented DIY build was also that basic 2019 circuit, wherein I went from an EH KT88 , to a tiny 12 watt plate dissipation Type 6005 military Finals tube. Because of the symmetrical shape of the tube ( a round cathode tube, a round control grid, and a round plate ) the stereo 2021 amp seems to easily outperform every Finals tube I have ever used.
In the case of KT88 amp results ( which remember...... in 2019 ......ATE the VAIC 2A3 monos ), I would estimate the 6005 tube's use alone is a 15 to 20 % improvement. That is huge. The 6005 I can easily hear as ultra special, when ALL my B+ circuitry is employed. I am excited .
Hence 2022's HFV " TRIPLE " 6005 DIY experiment, ( to see if I can recommend and live with the skewing trade-offs VS low Z drive to a 15 inch woofer, of a 3Xs Parallel 6005 Finals stage ), VS the inherent purity of a single 6005 Finals tube. ( 9 and 3 watts respectively. ) Will the 9 Watt TRIPLE exhibit an overly objectionable " choir " effect ??
' Need to get back to work on the mono Triple amps - before the end of this year. !! This mentally intrigues me , as to what will become the perceived outcome !!! I will end up owning them both. The way forward rests on my shoulders !!
Jeff
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Thanks for that info. Some of it i still remember, some of it i will need to refresh my earlier notes first before i can understand them properly. And others are entirely new to me.
Some thoughts in no random order:
1) Interesting point about the quality of the DC vs AC heating - I was not aware of that. So learned something new. That made me pull out the stock schematic of my 2A3 - it has a plate voltage of 395V actually (edit: which seems very high, come to think of it.... 2A3 should have a plate voltage of 300V max; OTOH, the grid voltage is much higher as well) and the 6SL7 is at 196V. And yes, all the filaments are AC heated (2.5V for the 2A3, and 6.3V for the 6SL7 tube).
2) It's funny you mention that the 300B was picked over the 2A3 for the greater power at the cost of quality - I do remember people with 45-driven amps saying the same thing about the superiority of the 45s. 1W was a bit too low for me then (and now).
3) What are some good 2A3 tubes these days? I no longer have the patience to chase NOS or "barely used" tubes and much rather prefer current production/easily available stock.
4) Is there a particular driver that works best with the KT88? I see schematics that use 6N1Ps, 12AX7s and 12DW7s. Not sure which of those, if any, would work better.
I also just realized that we (I) have taken the thread very far off-topic - my apologies to the OP. Perhaps we should continue this over messenger.
Some thoughts in no random order:
1) Interesting point about the quality of the DC vs AC heating - I was not aware of that. So learned something new. That made me pull out the stock schematic of my 2A3 - it has a plate voltage of 395V actually (edit: which seems very high, come to think of it.... 2A3 should have a plate voltage of 300V max; OTOH, the grid voltage is much higher as well) and the 6SL7 is at 196V. And yes, all the filaments are AC heated (2.5V for the 2A3, and 6.3V for the 6SL7 tube).
2) It's funny you mention that the 300B was picked over the 2A3 for the greater power at the cost of quality - I do remember people with 45-driven amps saying the same thing about the superiority of the 45s.
1W was a bit too low for me then (and now).3) What are some good 2A3 tubes these days? I no longer have the patience to chase NOS or "barely used" tubes and much rather prefer current production/easily available stock.
4) Is there a particular driver that works best with the KT88? I see schematics that use 6N1Ps, 12AX7s and 12DW7s. Not sure which of those, if any, would work better.
I also just realized that we (I) have taken the thread very far off-topic - my apologies to the OP. Perhaps we should continue this over messenger.
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No Hari,
A new W.E. 300B is surely the wrong advice - to give anyone !!!! .
My friend Randy ( with the huge 1945-47 cloned ALTEC H-110s - in the Firehouse ) on a 2-20-22 visit, had those newest Western Electric 300Bs in his amp. He must have paid about $1,500., for two tubes. What a mistake.
Other than being a larger and more powerful tube, his new WE 300Bs could not outplay an inexpensive ( less than $10.00 ) GE Type 6005 tube, at his firehouse, on his nice ALTEC system.
Common sense :
Always avoid tubes with asymmetrical electron emission, filament structure to plate structure !!
THE only 300B to own would be ones without a hanging W or M - shaped filament.
Jac Music ( EML, Emission Labs ) thoughtfully makes such premium 300Bs and 2A3s, which have HARP in a monoplate construction.
Do not be thoughtlessly taken-in by the public HYPE and W.E. advertising baloney.
A harp filament inside a monoplate structure is a must .... for a superior 2A3 or a 300B. Basic laws of physics, etc. apply.... in a tube's design.
Jeff
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Yelamanchili manohar
Well-Known Member
Just my 2 dumb cents...so please read my below signature, and please take my opinion with a large...make it very large..pinch of salt 
I've been through SS dacs and tube dacs. SS power Amps, and tube power amps . I always felt that tubes do instrument separation better. They also do depth of sound stage better. And if the speakers are efficient, I also found their bass texture and slam better.
In the end, I believe it comes down to the speaker in question. So among tubes vs SS it comes down to the speaker and listening taste I guess. And no...none of my amps sound like dipping gravy and laid back. They are extremely transparent, just without the hard edges on badly recorded music.
I've been through SS dacs and tube dacs. SS power Amps, and tube power amps . I always felt that tubes do instrument separation better. They also do depth of sound stage better. And if the speakers are efficient, I also found their bass texture and slam better.
In the end, I believe it comes down to the speaker in question. So among tubes vs SS it comes down to the speaker and listening taste I guess. And no...none of my amps sound like dipping gravy and laid back. They are extremely transparent, just without the hard edges on badly recorded music.
Subbu68
Well-Known Member
Not any lady can match any gentJust my 2 dumb cents...so please read my below signature, and please take my opinion with a large...make it very large..pinch of salt
I've been through SS dacs and tube dacs. SS power Amps, and tube power amps . I always felt that tubes do instrument separation better. They also do depth of sound stage better. And if the speakers are efficient, I also found their bass texture and slam better.
In the end, I believe it comes down to the speaker in question. So among tubes vs SS it comes down to the speaker and listening taste I guess. And no...none of my amps sound like dipping gravy and laid back. They are extremely transparent, just without the hard edges on badly recorded music.
. Not a match??? the current gen call quits and go for the next 
...... So are these analogous to this hobby?? change amp , change speaker, change amp,change speaker.......Now that I have two sets of spkrs and two amps that's what I came to conclude and get confused.
Last night session, i switched my temp OBs to Elekit SE from ACA monoblocks. There was a difference with the same track as you wrote.
Well actually I have heard the Rethm Saadhnas, multiple times , which I believe are over 100db sensitivity.
The owner , @bhaskarcan , might elucidate what amplification was used for those beauties …
From what I know he has experimented with different types of amps (tube PP , SET , solid state , hybrid etc ) over the years and has settled with only SS amps.
And humbly , there is no single ‘best amp’ in audio world. Even Dan D’Agostino would not claim so for his Relentless.
I do not know the FM with sensitive speakers you refer to, nor do I know you. What I say is not any reflection what so ever on either of you, or others in audio.
I DO have one important comment to make. The weakest link in the playback chain is the amplification.
Almost ALL amps do NOT come close to cutting the mustard to make ME happy with what I hear. It is a universal / world-wide audio amplifier problem we face.
Ask what amp types do YOU prefer, from all you have heard?? What do you like the best , a bit of............cancer, polio, a severe cold, congestion-upper tract? Measles, mumps, general sluggishness??? That is about what we have to choose from.
Jeff
Sanjay13leo
New Member
From my experience the consistency from the Solid state has far more in returns compared to a tube amplifier, after the honeymoon period, there will come a time or urge for tube rolling or missing out on details or frequency.
Tube Rolling is fun
Subbu68
Well-Known Member
And money..
Why did I get Elekit DIY kit - auto biasing and my cupboard has a box full of tubes...
My experience has been the polar opposite. Tube amps ended my upgraditis.
I have done tube rolling only once with my 300B amplifier and found not much difference.
sachinchavan 15865
Well-Known Member
Don’t think there’s much point in debating over two proven alternative technologies for the same purpose and decide which is ‘better’. If either was clearly ‘better’, the other would have died by now. Also, the 2A3 club sometimes comes across as exclusive/elite. Granted that provided certain synergies, for certain kind of music it sounds divine, but doesn’t mean that the alternative approaches are inferior. They are just different. And we should be glad that designers and users think in different directions. So we have varied options suiting different budgets, room conditions and musical tastes. Also, how boring the hobby would be otherwise!
Agreed. It isnt a matter of "better" but what attributes one prioritizes when listening to music.
As an admitted fan of the 2A3/SET sound - the thing is, they sound so unique that if you love the sound, it will absolutely blow you away and nothing comes close. Which is why those of us who are proponents of that tend to be such vocal proponents of it. It isnt meant to denigrate other approaches.
well said, in fact generalizing into tube and SS sound again is not really the right thing
There are SS sounding like Tubes and Tubes sounding like SS. in the end its about the design .But within tubes a 2A3 based will be different from a 300B or any other tube, again due to changes in design.
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