Interesting no one brought Gohzirah or the PX25. Two tubes I have not been lucky enough to hear.
If I were giving advice, which I don't, I would advise someone interested in tubes to find a really high quality integrated like a Manley Stingray featuring the EL84, if they weren't sure they would enjoy using tubes or were unsure about their competency with biasing, etc. Or I would suggest a KT88 amp like the Cary SLI-80 (comes with 6550, which is very similar and can easily be changed out with the 6550's sold). KT88's being the most lucid musically of the bunch. Then work towards an extreme - either single-ended topology, 300B, etc. I would not dive into tubes at the 845 end of the spectrum, unless I had more money than most, or was accustomed to changing out very high-end components every year or two - because if you hate your tube amp which is the size of a Yugo and puts out as much heat as a wood burning oven, you're still stuck with it. |
While I've heard amps with just about every tube type, here's what tubes I can comment on in context of hearing all on the same system -- mine -- but of course in different amps:
300B -- SET, PSET, PP
845 -- SET, PSET, PP
45 -- SET
KT88 -- SEP, PSEP, PP
EL34 -- SEP, PSEP, PP
EL84 -- SEP, PSEP, PP
211 -- SET
2a3 -- SET
PX25 -- SET
Amp design, circuit topology, quality of transformers and related circuit parts, and even the tubes you select all have profound effects on amps built with these tubes. But there are some characteristics that seem attached to the tube type itself, which shine through differences in implementation.
45: Penetrating intimacy in the midrange, soft top, deep natural bass. However, even on 101db/w/m Zu Definitions, the dynamic limits of a 45 amp in SET configuration are so acute that it is not practical in American listening spaces. The first watt may be critical, but your average SPL doesn't have to be all that high at 12' distance for you to run smack into the dynamic compression (and distortion) of 2 watts more often than you like. Music with muted dynamic range, however, can be beautiful through this tube. I wanted to be bowled over by the Yamamoto but the dynamic limits couldn't take the 45 all the way.
2a3: Similar limitations as the 45. A little less neutrality than the 45, more romantic. Lush.
300B: A big 7 or 8 watts makes a difference in maintaining dynamic clarity. Magical midrange richness is a real trait, easily identified. Rising harmonic distortion in the bass region generates characteristic bloat that can be designed out at a substantial price. Treble "spray" is lush and exciting but with some tubes, like mesh plates, is on the far side of real.
845: Big, meaty tone. Much more bass discipline than 300B and top end extension is more neutral. Midrange is unmistakably triode and rich, but gives up some of the 300B's delicate articulation. Dynamic slam however walks all over the 300B, even when that tube is used in PSET configuration for similar power. The quality that most sticks out with respect to the 845 is its sheer drive. On some speakers, this tube is unbeatable, except perhaps by the Godzilla T-1610. The 845A, 845B, 845C, 845M, KR 845 and the vintage RCA or United are all different enough to overwhelm these distinctions.
211: Similar to 845 but a little drier.
EL34: Warm, round sound. No one ever regretted listening to an EL34 amp.
EL84: Sweet, open, driven, with surprising bass discipline in SEP topology. Amaze yourself and embarrass many high-buck SET amps with an Almarro A205mkII.
KT88: Take-charge tube with speed, transparency, tone. Strong tube that can give you up to a solid 15w/ch in SEP configuration, with a "whiter" more objective sound than most triodes, and very fine tonal and detail balance. The Acoustic Masterpiece M101, for example, can take a lot of triode amps to school.
PX25: Best bass I've heard from a triode tube in SE. This is the "objective" triode, stripped of the 300B's up-front emotion, with a few extra watts over a 45 to put the vice-grips and some kick to a speaker cone. Lacks the emotional romance of the 300B, but midrange is open and fluid, just a tad tonally anemic. The top end dispenses with the 300B's spray. The Audion and Art Audio PX25 amps are the smoothest segue into low-power SET for someone coming from Push-Pull.
I can say more about each tube, but is this a start for you? For reference, my systems actively use 300B, 845, and KT88 amps today.
Phil |
Friend
As you give up watts you gain communication of emotion, realism, refinement, and resolution. The 45 is a VERY musically accurate tube. The 211 offers more power but at the expense of the aforementioned.
Studio 1 |
About Klipsch - once the man, always the man. He and Bob Carver pretty much to my mind are two of the great contrarians of the audiophile world.
I hesistated to bring up the Rocket, but it is a cool design, and with the single-ended-like output (though not 100% there) it was definitely the way for me to get my feet wet and still have a lot of choice. I have toyed with getting rid of it, but never can quite pull the trigger when someone offers me money. I may go so far as to say it's Had's most original design.
Rchau - interesting about the 6SN7 topology and implementation with the 300B. Can you explain - I'm interested. What would the other ways of doing it be? |
Glassaud,
You bring up a good point that can be extended to many 300B amps. In my opinion, many commercial 300B amps use the wrong driver which leads to the problems Glassaud describes. These problems contribute to the general opinion about 300B's that were mentioned in post by Gregm. This is probably due to manufacturers having to use readily available tubes rather than rare and hard to obtain tubes. The 6SN7 driving a 300B is a common design but with common problems. In think the 2A3 and 45 are easier to drive so they don't have this problem. |
Very interesting Biomimetic, the Rocket uses some dc bias in the out put transformers, just as in single ended-the ONLY push-pull design to my knowledge that does so . BTW I've heard the paradigms and couln'd agree more, just on low powered SETs I lean toward Klipsch- say what you like the man had some brilliant ideas that deserve our repect. Dennis used some great ideas, truly innovative in the Rocket- I'm tempted to try one myself. This from a man hooked on SE from the begining.
Good luck and good listening
Richard |
Interesting Glassaud, about the AES topologies.
I use a Rocket, and have never had any clipping at 20w in triode. Maybe during a test of the system or something, but not in daily use (at least to notice while listening normally). It's the original one with the 6922 inverters. I have found it to be superior in almost every regard to the design at 30w triode using the 12AX7 inverters. I've heard them next to each other, and found there was really no comparison. I like Cary - reasonable customer service, decent designs with plenty of options for retubing, including EL34's and 6L6's in the Rocket. But I wouldn't want it if it had that sluiggish sound with the 12AX7's. Of course I've have also found that by cranking the gain, and rasing the bias to about 220 from the stock 200 (something Dennis recommends actually) at the input, I can listen to rock just as easily as chamber music. I use a vintage phonostage with adjustable gain and equalization. It's solid state, pretty modified, run through a UL tube preamp, and it makes the gain pretty hot. It can get uncomfortably loud, but doesn't clip. The bass is also very tight run this way.
Of course, 20w is not 2-8w. But I do think the philosophy of "the first watt should be enough, the rest should be back up", is the best way to get a real dimensional life-like sound from a system, regardless of loudness, front ends, speaker pairings, etc.
I just use a pair of Paradigms for my speakers, which while not awesome speakers, are reasonably sensitive and good buys besides. I've heard many salespeople say (anonymously) that they bought them because at the end of the day they did many things right that the $3000-6000 speakers did wrong. My room is an L-shaped (yuck) 40 square feet, and the dispersion of the Paradigms is not laser tight, like it was when I was running them with Marantz mono's at 125w. They sound better, and more holographic at a KT88 20w.
The other great myth of SET's is that spec's are everything. It's one of those few times when you have to actually try it to really know if it works. Hopefully there's always a friend with a system to poach on to try stuff out, or a friendly audio store (or at least one that will put up with bringing in equipment - hopefully they are curious about what they aren't carrying). |
The Cary is one of my favourite amps for it's sweet, forgiving sound, my AES version is similar. That said both amps in stock version suffer from a design error that causes slew limiting, an inability of the driver circuit to provide enough current to the output tube to allow the high frequencies and fast transients to react quickly enough. The result is rolled off, slightly sluggish sound. In the AES, the 300b's can be replaced with 2a3's or 45's and the problem is solved. Otherwise the driver stage can be redone ( I wrote it up in Glass Audio magazine in the 90's ) and the result bears very little comparison from the stock circuit- very fast, detailed sound. If you can put 2A3's in your Cary, reducing the bias current %20, you will get a taste of what single-ended is capabile of.
Good Luck and good listening
Richard |
for some applications it works well (small room, jazz, simple vocals, etc.) It's just that for a low power amp, you end up running at max power alot and possibly clipping which takes you into a higher distortion range on the amp. COuldn't agree more. However, my experience leads me to seek at least 20W before clipping for orchestral music; even with ~106db spl on the spkr side, I still needed extra energy when using a 300b pushed to 7W. And note that the amp was crossed at ~120Hz, (directly connected to the drive unit, passive line level xover). In other words, I found it necessary to have a headroom of ~10+ db over the speaker's reference 1W/1kHz etc available in the amp. But of course, a highish load impedance and good phase characteristics help the situation. |
Biomimetic, good stuff, keep it coming. |
Bio-Yes, it is Taurus Audio in the bay area. You can usually find me there on Saturday or Sunday afternoons hanging out. That's why I have logged many hours with the Mastersound. I refer to Taurus Audio as the audio version of "Cheers".
The phonostage that Louis runs is the big Aesthetix. The stock tubes have been changed on the Mastersound as well as some of the stock parts. too bad the Euro is high against the dollar. When Louis first brought in the Mastersound it was $6 K. Of course, the Euro was trading at 1.23 Euros to the dollar then.
As to your other question, there is no set rule on speaker pairings and amp power. Obviously, a 2-3 W amp is not going to get you earthshaking sound unless you have really effficient speakers (94+ dB). However, for some applications it works well (small room, jazz, simple vocals, etc.) It's just that for a low power amp, you end up running at max power alot and possibly clipping which takes you into a higher distortion range on the amp.
I used to have a speaker which was 92 dB and never dipped below 8 ohms. It worked well enough with my 2A3 but the bass was always loose. That speaker just needed more power to control the bass. In another case, I heard a 10W amp driving a 90dB and 8 ohm speaker which had really tight bass and marvelous sound. You just have to find the right pairing. |
Rchau - Are you talking about the guy at Taurus Audio in the Bay Area? What a *GREAT* room that is, as in *WOW*. And a cool guy too. The only system I've heard I liked as much was an Airtight (the KT88 one, I can never remember their designations) with a pair of large Opera Piega's. But the turntable was not on par with a Hyperspace. I sort of remember the guy at Taurus saying the phono was 47 lab... but if he's your friend, maybe you know differently...
I started a thread "Lowest power amp with Joseph Audio RM33's" - I have heard of someone using a 2 or 3 watt 45tube SET with a Pair Harbeth 40's (was in 6moons I think) and getting decent, though not spectacularly loud results... but of course I got a guy who told me "100 watts solid state minimum"; which is to me what leads to this sort of view of SET as difficult and unreliable. No one ever checks the ohms on the speakers which even if it's 4 ohms minimum, should be workable at 15 watts, if they're good. It seems to me a pair of Revel M20's at 4.4 ohms minimum would work as well with a Cary 300b as a Levinson, and might possibly have good synergy (crazy rich mids, and extremely neutral speakers), at least for a cheaper system. So 6 ohms minimum to me seems like it should run just about anything... or am I hi-jacking the thread? |
Thanks Joe for the kind words, but in all modesty I rarely use my title even in a professional setting. It's too prentious.
For Joe,
The PX-25 is a pre WW-II power triode developed in Europe. Real PX25's used an odd B4 base rather than the more common UX4 base and could put out a bit more power than a 300B. The PX 25 is a bit more linear than the 300B and supposed to have better extension at the extremes. Real PX25's are rare and I have only seen them in Japan. KR started making 'PX25' a few years ago. This tube has curves that are like old PX25's but slightly different electrical ratings. The new PX25 has a lower maximum plate voltage and can be found in both b4 and UX4 basings. The only amp I have heard using the PX25 is the Art Audio PX25.
For Bio,
The main point in my message to Joe is that implementation is more important than the sound characteristics of a particular tube. The Mastersound 845 reference is the best 845 amp I have heard. It is even better with the right driver tubes and some mods. My friend who is a long time Mastersound dealer also runs his with a Hyperspace into JM Lab Utopias. Other 845 amps I have heard (Air Tight, Quadric, etc....) have not been so transparent. I am biased because compared to a 2A3 and 45, I do find the 845 a bit thick.
Even though I agree with Greg about the 300B in general, I have heard 300B amps that do not have those flaws. Try listening to a Shindo 300B limited.
One final point, I think the sensitiviy issue with SET are often overblown. For many types of music, 8 W into a 90dB speaker is fine. I ran a 2A3 for many years into a 92 dB speaker. Except for large orchestral, it was fine. Your own mileage may vary. Remember that it takes double the power to increase the sound pressure by 3 dB. |
Hi Bio: nope, the speakers were a mess
The tubes were driving a tractrix horn loaded lowther ex4. 120 Hz horn. Then I had to use a suitable bass driver capable of playing the game (that was fine, a Supravox 400 did the trick). Then, not surprisingly, I wanted to get rid of/tame that annoying wizzer-related intermodulation the lowther had by extending the upper end. Of course, wishing to play purist, I couldn't consider sticking a filter onto the lowther, now, could I?
So, I was looking around a tweet to mate well with the lowther. Never found one; many available supertweets, for example, Murata, are low sensitivity -- which in turn means another amp, sonically matched to the lowther amp, but producing ~4x the power or more... a big mess:)
I like your point about the exotic nature of SETs -- similarly a prewar Leica. |
True, Greg. I should have been clearer. There are zero feedback SET's, but I think it's more of a "differential of the circuit" except in the case of direct heated tubes - or am I wrong about that? I do think, for all the noisiness of a direct heated tube, they do have something "special" regardless of their own internal topology. And it's never so with transistors. I disagree with Dr. Chau about the 845, which to me is actually quite a transparent tube. Of course, I've only heard them implemented in Mastersound's amps with a Hyperspace/47 lab phono pre/Cardas cartridge. The thing I find cool about SET's and the reason I love using them, aside from just the fact that they are actually exotic (like a minty Giulietta Veloce, or a vintage 1930's Rollei camera...) is that the holistic approach is the only one that works b/c of the low power; do you use speakers that are really super neutral, like Joseph Audios or go for the total overload of richness like a pair of Proac's or something? |
For SET amps, I think you have
to consider the amp and speaker as one unit. Very nicely put! Indeed, in the old times, the speaker came with its amp -- together. Remember those old radiogrammes (or whatever they were called) and radios? The 1610 is nothing like the 300b. It's huge and made by a company called KR. They also have an amp using it (which is where I heard it). In single tube/channel config they manage +20W / channel. I think they must be using transistor drivers -- but am not sure. Similarly, the 211 requires a different circuit than the 300b. But it's seriously more powerful. Of course Biomimetic is right about feedback which can and is used to stabilise circuits... however, one can stabilise a circuit without feedback if one is into that sort of thing. One can't with a transistor for example. |
Here's a great offline response I got from Dr. Chau that I'm posting with permission:
*******
First, you have to realize there are no absolute rules to the sound of a
particular tube. The end result does depend on implementation. However,
you can breakdown trends in two ways. Each family of tubes does have a
commonly accepted 'sound'. Also, many SET manufacturers have a house sound
including Cary.
300B: the most recognized SET tube. Often said to have a rich, warm and
glorious midrange. Also often said to be a bit rolled off on the top and a
bit loose in the bass. Still, it's reputation is from the glorious
midrange. The first popular directly heated tube in the US (had been
popular in Asia and Europe for much longer).
2A3: similar to the 300B but much less power (typically 3W). A bit cleaner
in the mids, more top end, and much better in the bass. The bass from a
2A3 is really good depsite the low power. This became popular in the US in
the late nineties since it was cheaper than the 300B and considered to be
cleaner sounding than the 300B. FYI-I currently use a 2A3 at home although
that will change in a week or so.
45: an even older tube than the 2A3 or 300B and even less power (2W). This
is the current hot tube in SET. Considered even more transparent than the
2A3. Supposed to be better in every way than the 2A3.
The above tubes are directly heated triodes but use an oxide cathode like
most small signal tubes. The next group of tubes are transmitting tubes
and use a thoriated tungsten heater/cathode
211: a popular transmitting tube. Can put out 12-15 W on a single tube.
I've only listened to a 211 on several occasions. I find it a bit thicker
sounding than the 2A3 and 45, more like a 300B.
845: the current hot high power SET tube. can go up to about 18 W on a
single tube. I find it somewhat less transparent than the 211. Many
commercial amps are available with this tube now.
The bass on the 211 and 845 is probably a bit bigger than the 45,2A3, or
300B but not as quick.
Other tubes:
212, 807, 811, 833A-other transmitting tubes. Some are really large like
the 212 and 833A. These can put out a lot of power (100W for a 833A) but
can be dangerous as they need very high voltages on the plate to achieve
max power. The 811 and 807 are smaller and in between the 845/211 family
and the 45/2A3/300B family.
10, 101D, VT52, etc. other small triodes in the vein of the 45. These
often are considered even better than the 45 but have really low output and
are rare. Very few commercial designs are available.
The above comments are gross generalizations and based on my own
experiences. Again, a good design can change the characteristics. A
current thread in the forums is to run the 845 at much lower than normal
voltages (i.e. lower power) which changes the sound.
Also the above tubes are all triodes. One can get good single ended sound
from pentodes and tetrodes. I just purchased a Shindo Cortese to replace
my 2A3 amps. These run a F2a pentode.
In addition to a specific tube sound, manufacturers have a characteristic
sound. Cary certainly has a family sound. Even though the first SET I
heard was a Cary and I used to own a Cary, I'm not a fan of their sound.
As to you question about moving to another tube, you will can find big a
difference even if you move to another manufacturer's 300B amp. It all
depends on what you want in terms of sound. For SET amps, I think you have
to consider the amp and speaker as one unit. This is especially true for
the lower power tubes. If you can, try to listen to a 2A3 or 45 amp since
I think you'll hear the biggest difference in these tube tubes compared to
a 300B. You can only answer you question by listening.
**** |
I agree with greg except for the feedback thing - plenty of variable feedback in tube circuits, depending. Lower than solid state, but not negligible. And interesting about the 1610. However, another thing besides low power to think about with say a 2A3, despite how linear they are, they also are inherently very noisy. To which I would add: 45 tubes (even lower power than the 2A3) and the recording studio fav tube, the EL519, which is a little like the EL34 but more linear. I think only EAR makes a EL519 amp, and, well... EAR, not exactly a fan... So it's $8000 at least for an 845, a company that will irritate you in their treatment of customers like EAR, or a noisy low power tube for $2500. |
Gregm thanx for a great response. I'm really surprised at your impressions though. I guess I've been infected by the marketing you mention ;^)
Have you heard a PX25? I've never even heard of a 1610 tube. Also, the 211 is a different kind of tube from the 300b right? I understand the 211 and such is a transmitting tube (radios, etc.) where the 300b was actually a repeater type tube originally created for use in amplifying phone signals travelling long distances. (In fact, I've heard that there are lots of Western Electric 300b tubes sitting on the bottom of the ocean!) Anywho... |
Well, I can give you a reductionist, and highly subjective rigmarole based on limited experience with products sporting 300b, 211, 845, 2a3.
All tubes can be usefully operated in a no-feedback circuit. Good stability. So, basically they're VERY good amplification devices (i.e. better on paper than the best transistors for example) despite the need for output trannies. Having said this, more or less, objective piece -- here goes:
300B, good because of availability, reasonably priced tube and trannies, the worst of the lot in extension and sonics. Excellent tube for marketers, but other tubes are catching up. Reasonable linearity and some dynamics. Low power -- but still workable, somewhat (say a 112 db spl 1W/1m speaker). Basically this is a "nearly" tube: it's nearly good, nearly extended, nearly excellent sounding, nearly...
As such it lends itself to many applications -- for this very reason. I hate this tube in any application EXCEPT for powering an upper midrange driver alone. Maybe a tweet, but wouldn't know where to buy suitable output trannies.
2a3: as above for availability etc; good pricing to boot. Much better sonic attributes than the 300b even, BUT minimal power capabilities. Probably has excellent dynamics, bass trable, mid, lush and clear, veil-lifting and all that -- but given most speakrs' abysmal efficiency, you'd need an army of 2a3 to hear them. In which case of course you'd lose some of its quality attributes. Life's tough.
845: not too good availability (but improving), expensive, and variable quality trannies all expensive. Good power and extended linear region. So, so, low freq. (so what -use a mosfet instead). I like this tube -- but it's depressingly expensive in most implementations.
211: now we're getting serious. Availability starting to get better and you no longer have to be Mr Gates or similar to obtain it (but being rich remains an important consideration). Trannies still awfully expensive. High voltages. Now this is where SET leaves the whispers and enters the premier league. Good sonics, good extension and no bulls...t driving capabilities. In fact, it also has reasonably low output impedance to boot!
1610: one you didn't mention. Very serious driving capabilities, better stability with loads than 211 and capable of excellent energy swings within linear operation. BUT, very limited availability.
_______Voila___
Let me repeat that I'm personally comparing these tubes to one another -- so when I say I hate X tube it's an exaggeration and said in context -- right?
And if s/one offers me a 300B, I'll jump on it!
Cheers |
Does anyone have an opinion on the different characteristics of these tubes: 300b, x45, 211, 2a3, PX25. Thanx |
I was expecting to hear something like, "In General, 300bs have better midrange compared to 845 and 211 but you give up power, 845 have better frequency extention and more details than the 300b but is close to the 211, etc." |
Your question is perplexing: what exactly do you want to know?? The product differences? There are very many products using the tubes you mention... The difference between the tubes?? If so, it's difficult to say much more than that the 211 is more powerful & slightly more extended in its linear operating region than a 300b. The 845 is also a more powerful amplification tube... They use different voltages and output trannies. Ultimately however, the sound you get depends on the circuit as a whole -- not only the tube.
You're listening to a 300b already... |
Thanx for the input. Still looking for impressions from people who have auditioned different SET tubed systems on the differences. |
Personally i think the Cary 300LXI has poor dynamics and weak , rolled off bass. Depending on your speakers, any 300B,2A3,45, or 845 should be considered. Do some auditioning with your speakers. |
I heard a Mastersound 845 with a pair of JM Labs and a Hyperspace that destroyed the Cary Rocket I own... but you won't find one for $2500. BAT would be a different direction, but better... I don't know. I like the Manley Stingray, but it's not quite the same vibe as the Cary stuff. It's funny when you start to think about it b/c after about $2500 used the next jump seems to be $5000-8000; Mastersound, OTL's like Atmosphere or Graaf, or seperates which would be the same as what you've got, but with more power but not necessarily quiter b/c it's a single-ended tube amp. |
