300B or 2a3 SET Class A for Heretic Model A?

I had the same questions when looking and because of all the recommendations on here I called Aric @aricaudio. This turned into many calls and emails to figure out what would work best for me. His customer service and equipment is top notch.

Aricaudio.com

@superelmar A lot depends on your room size. When you are using SETs, if you run them past about 20-25% of full power they tend to make more higher ordered harmonics, which, since the power is usually on transients, tends to make the amp sound more 'dynamic'. This is because the ear uses higher ordered harmonics to tell how loud sounds are.

So a typical 300b amp might make about 7 Watts, but it really has a bit less then 2 Watts that are really usable (if you want to hear what the amp can really do).

So my recommendation is to consider an amp with more power. My speakers are 98dB; 2 dB less than yours and my room is not particularly large. I run amps with about 50 Watts; they are loafing most of the time which makes for much lower distortion so greater transparency and smoother sound.

If you are really stuck on using 300bs or 2A3 class A amps, consider something push-pull as they have much higher amounts of usable power, 90% instead of only 20%, owing to far less distortion.

Here's an example of what you might consider:

Raven monoblock

Something else to consider is there are now class D amps that are just as smooth, revealing and involving as the best tube amps.

Thanks guys!

Had good memories of SQ-N150 from Luxman, but it didn’t was quite as magical as my former Mastersound Compact 300B, anyways drove a Zu and Klipsch effortless, my room is 28sqm.

BTW Still enjoying the Voxativ Zeth Absolut System, absolutely great one, dunno even why I got Heretic and look for a 300B!

2A3 over 300b for me. 45's even better but you don't have the efficiency for them. 

Well are 100db if that doesn’t work for 45…

Well are 100db if that doesn’t work for 45…

@superelmar exactly! You need about 6-7 dB more; type 45 amps are better suited for headphones.

I have transformers in my inventory for a 45 amp, as well as a 2A3 push pull. 
 

I look forward to getting them built and comparing them. 
 

As stated above, I would be looking into a PP 2A3. Very curious about how tyt would sound. 
 

I use a DIY SE EL84 with my Cornwalls and it drives them with comparative ease. Now, I don’t play particularly loud, and I’m not a bass head, so others may not find that satisfying. 
 
Do really like EL84’s, I do :) Listening to a pair of UA-1’s now, and even in their poor state (just got them) they sound quite lovely. 

It always bothers me when some asks about a lower power tube amp and someone chimes in with, get a higher powered amp. To me if you want a 300b, 2A3 or 45 amp get one. I have all three. I listen to music all day and at good volume and one room is 1400 square feet. These amps are the best, and at the same time there is a culture around them. The people who espouse the more power mantra are not part of that culture and are irrelevant if you really want a low powered tube amp that’s about sweetness and musicality and tactile-ness. And I’m sure many people feel they have this with their un-low powered tube amp set up. Good for you. But what I'm talking about is not what everyone wants and that’s totally fine.  It would be silly to want a historic style 300b amp and its ilk and not at least have the experience that got you curious about one in the first place. It’s a hobby, try things doesn't really help to ask questions. Just experiment and sell on what you don’t like. It will still be cheaper than golf or wine. There are no right answers and crazy little accurate information. Everything in this world is personal. 

I’ve run 845 SET amps (Antique Sound Labs, USA) and been very satisfied with their 27watts per channel.   Very quit, lovely midrange, tight powerful bass and extended highs.   Great imagine and overall tonal quality.   They matched well with my electrostatics.   If you are concerned you need more umphf, then you might consider a SET based on the 845 tube.

Another 2a3 fan here it has a clarity and a speed that 300B doesn't have, to my ears at least.

Again don’t listen to anyone here, me included😂

With all due respect to others here, you don’t need a higher power amp, and a 2A3 amp is or is not better then a 300b, there is no such thing in this world as better. Every time you change your speakers or your amp, you’ll have to decide if you hit on the right equation. If you didn’t hit on the right equation it’s not the amps fault, it’s just that situation. I had a 45 amp that didn’t sound good with the Altec's I had, didn’t sound good with Tannoys, and I just put it aside and one day tried it with some speakers I was using at work and bingo. Again it’s a culture.  It’s a tremendous fun little corner of the high fi world. And if you get into deep enough you’ll find yourself looking for copies of Sound Practices magazine. 

Very good points yaluaka.  Every component choice involves some kind of tradeoff, and if low-powered SET is your thing, you either live with some compromise on ultimate volume capability or a MUCH more limited range of speaker choices.  The right sonic choice depends on a wide range of variables and one should not limit the candidates by the type of tube, or for that matter the topology--single ended triode is NOT inherently better sounding than pushpull or output transformereless, etc.  I own a parallel single ended 2a3 amp, a pushpull 45 amp, and a pushpull 349 amp.  The parallel single ended 2a3 is, by far, the most expensive and it is terrific sounding, but, to my taste and in my particular system, the pushpull  349 is the best overall.  If I had to pick the best amp I've ever heard, it would be a custom built OTL amp or the Western Electric 59B amp (pushpull 252 tube that is an ultra rare and expensive tube similar to a 300b).

After hearing many amps employing these tube types, I do come away with some very general observations about tendencies, although there are many exceptions.  The 2A3 tends to be leaner sounding (not as much warmth and upper bass) than the 300b, which also means it has a clearer sound and it has very good dynamics and has tighter bass as compared to a 300b.  The 45 is very nicely balanced and has tight bass, and sort of lies between the 2a3 and 300b in terms of midrange warmth.  There is something "beautiful" about the midrange for the 300b.  It has a very warm, comforting sound, but, it does not have quite the dynamics and lively sound as the other two types.  I've heard pushpull amps that are very similar, by the same builder, employing all three types, and these rough characterizations come through.  No particular sound is "better" and much depends on the speakers being use, the room acoustics, etc.  

+1 for Aric Audio

Give Aric Kimball a call, he's a great call even if you don't buy his equipment. He offers 2 different 300B amps, a 2A3 amp, an EL34 "Push Pull" amp, a KT88 "Single Ended", and a pair of KT monoblocks. I own his Motherlode XL preamp, and the EL34 "Push Pull", and they are ridiculously good with high end components.

Ralphs (Atmasphere) tube amps get great reviews (though I've not heard them), and would be a great option for OTL amps. He even suggested that you look at the below Raven monoblocks.....tells me a lot about his honesty.

The Don Sachs/Lynn Olson Raven monoblocks that Ralph suggested, are Don and Lynn's end game amps.....though end game costs $10,000 for each monoblock

It always bothers me when some asks about a lower power tube amp and someone chimes in with, get a higher powered amp. To me if you want a 300b, 2A3 or 45 amp get one. I have all three. I listen to music all day and at good volume and one room is 1400 square feet. These amps are the best, and at the same time there is a culture around them. The people who espouse the more power mantra are not part of that culture and are irrelevant if you really want a low powered tube amp that’s about sweetness and musicality and tactile-ness.

@yaluaka I've tried plenty of SETs over the last 30 years as well as designed and built my own using the 45, 2A3 and 300bs. SETs do not rule the roost in any of the areas you mention above. But there are plenty of PP tube amps that fall short; if you've not been exposed to the right PP amps I can easily see how you came to your conclusion.

Here are some things to consider: The mark of the best systems is they never sound loud even when they are. You may have noticed that your SETs seem to get plenty loud but what is happening is the distortion they make causes them to seem louder than they are (there are sound pressure apps for smartphones that can easily show what is happening). When you have an amplifier with less distortion it will be very natural to use more power and enjoy it.

The distortion of SETs increases linearly as you increase the power level. Above about 20-25% of full power, the higher ordered harmonics start to show up. They appear on transients (where the power is) and because the ear uses higher ordered harmonics to tell how loud a sound is, this causes the transients to sound louder, giving the amp a very 'dynamic' quality.

IOW the dynamics of SETs is really distortion and nothing more- real dynamics come from the music.

Bandwidth is another problem; with greater power its progressively harder to make an output transformer that really has hifi bandwidth. So usually the highs are made right and the bass suffers, since the kind of speaker you need to really take advantage of an SET (likely horns) often don't have deep bass response. So if you really want to experience the music properly you'll need subs and driven by the preamp rather than the amps.

OTOH, there are PP amps that are every bit as involving that don't have  these problems. Consider though that if you really want to compare apples to apples, the PP amp might have to use the same kind of output tubes, perhaps it should also be class A and zero feedback as well, to level the playing field? Usually these things aren't considered when making comparisons. You might also consider what happens if the PP amp makes the same power as the SET; for example if compared to a 2A3, perhaps the PP amps only makes 5 Watts? Again, to level the playing field.

If you work to eliminate these variables you find that SETs really don't have an sonic advantage over a well designed and built PP amp.

Hey Atam,

you’re entirely right, I have push pull amps too and love them. But that’s not my point. The 300b/2A3/45/50 tube world is a culture unto itself. And I find that huge fun to be a part of. Not only do they (or I should say, they can) sound great, but it’s a very interesting esoteric part of this hobby that’s great fun to learn about, historically both from hifis inception and more recently with Japanese and other Asian cultural approach’s to this era of equipment design. 

It has been a while, but, I have heard the Atmasphere M 60 and M 30 amps.  I liked the sound a lot--very alive and vivid without being harsh.  If you are looking for extra warmth, they might not be ideal, but, they are still very fun to listen to.  More recently (about three months ago) I got to hear their MA 2 (I believe) amp which is much bigger and it sounded great.  Some SET amps are also very lively and dynamic sounding within their restricted output, but, OTLs do the extreme dynamics too and should certainly be under consideration for a tube-based system.

we are a Mastersound dealer the compact 845 is a remarkable amplifier reliable, dynamic, with enough power to drive more moderately efficient set of loudspeakers 

one of the most memorable amplifiers I have ever owned in 40 years of professional system design.

Dave and Troy

Audio intellect NJ

Mastersound dealer

Another plug for Aric. I've owned three of his amps and was elated with each one of them. I just sold my Super 300B and I will miss it dearly. It just didn't fit with my new speakers.

Aric is the man and he won't steer you wrong.

I can recommend:

1. 300B integrated Allnic T-1500. I listened to it in Montreal Audio show and it sounds really great. It has 6sn7 driver loaded on choke - LC coupling.

2. Aric Audio Super 300B. It should be even better because it has 6v6 powerful driver tube with inter-stage transformer. That is very important for difficult to drive 300B.

3. Coincident Audio Frankenstein - mono blocks. It is also has inter-stage transformer and powerful driver tubes. I listened to this amp in my friend's system.

@alexberger I tried Coincident Frankenstein's with Altec Model 19's, thinking that the Altec's 99 dB efficiency would pair nicely, but unfortunately, the Frank's made the 19's sound under powered.   It's possible that the 19's impedance curve is demanding, as I've tried numerous amps, many of which didn't seem up to the task, as the sound was lacking in bass and dynamics.  I'm currently using McIntosh MC-30's and they are the best I've found so far.

Hi @pdreher ,

What is a size of your room?

In room smaller than 250 sq. feet 300B amp should be enough. I had opposite experience with McIntosh MC 30 and DIY 300B amp with my Altec 604E. But the room was small and probably 604E is a little bit more easy to drive versus model 19.

But I liked a lot MC 30 with Spendor 2/3 in the same room.

I don’t recall not liking a speaker because the amp had too much power but I’ve heard plenty of underpowered speakers sound bad. I’ve owned speakers that were 105dB efficient and sounded dull and lifeless with a variety of flea powered SET amps, along with PP amps of modest power ratings. It wasn’t until I hit them with 200 quality, clean, digital watts that these things really came to life.

That’s been an experience I’ve had multiple times over the years with different speakers. I own Audio Mirror SET45 monos and they really sound fantastic going into a 98dB speaker, but dull and constricted into an 89dB speaker in a modest sized room, even though their power rating suggests otherwise.

 I agree with Ralph that running the amp so it’s maxing out at around 25% of its rated power is a good strategy with SETs.

 I also have parallel KT66 and KT88 PP amps that are more tolerant of being driven closer to their max rated power. 
It’s really about experimentation and finding the right synergy, which will be dependent on your room size and geometry and your personal listening preferences, not something that someone can tell you on a forum.

 I also agree with the poster who said running low powered SETs gets you entrance to a cult, and it’s one where you can land on some magical combinations of speakers and amps. 
It’s all fun, so long as you don’t mind losing your eyebrows every once in a while.

 I also agree with the poster who said running low powered SETs gets you entrance to a cult, and it’s one where you can land on some magical combinations of speakers and amps. 
It’s all fun, so long as you don’t mind losing your eyebrows every once in a while.

Its really about SETs being a musical instrument rather than a music reproducer. Fun, but its not at all accurate to the recording. That profound ever-lovin' 2nd harmonic gets a richness that isn't part of the original recording; that is why I say 'musical instrument'.

@alexberger my room is not small @ 14' x 26' x 7.5' tall with a 6' wide opening that leads to an adjacent room.   My Altec's use Werner Jagusch crossovers, so it's possible they are contributing to inefficiency or negatively impacting the impedance curve, more so than the original stock crossovers, but I can only speculate.  In addition to the Franks, I tried an Elekit 300B amp and it too struggled to drive the 19's.  I did try a Line Magnetic 845 based SET integrated... and while it did sound fantastic in many respects, it emitted loud buzzing sounds from both the speakers and eventually the transformers... so as much as I would have loved that combo to work, the buzzing and transformer noise was a show stopper.  I'd like to try another 845 SET amp with the 19's again down the road... thinking Mastersound Compact 845, deHavilland Aries or Audion Shadows.

@pdreher Keep an eye open for an Art Audio Carissa. 845 SET and a great match with vintage Altec.

PS- I ran Valencias with Model 19 crossovers for a while and those things benefited from some juice. 

@rooze I love the sound of my McIntosh MC30's, but always have an eye out for reputable high quality 845 amps/integrateds to have as an alternate that I can swap with the Mac's for a different flavor.

“It’s really about SETs being a musical instrument rather than a music reproducer. Fun, but it’s not at all accurate to the recording. That profound ever-lovin' 2nd harmonic gets a richness that isn't part of the original recording; that is why I say 'musical instrument'.”
 

To me this is also a specious point, the idea of accuracy in recorded reproduction. I’m looking for something I  like. I don’t want a stereo limited by only sounding good with any particular music or record label. It’s not about accuracy, to me accuracy is anti musical. I want the music I listen to- to be engaging. Accurate is irrelevant, in fact I don’t think it exists. Perhaps an extreme view point. You get into set amps because you want to experience the music not judge the recording. 

“It always bothers me when some asks about a lower power tube amp and someone chimes in with, get a higher powered amp.”

Great posts yaluaka

All good amplifier possibilities by the OP. I'd like to suggest another possibility that would let you have your cake and eat it too -- Why not consider building an Ele-kit TU-8900 from Victor Kung at VKmusic.ca?

I have one and really love it with Avantgarde Duo SD G3 horns. The Ele-kit is an easy build and with the carefully curated upgraded parts that can be bought from Victor with the amp kit, it is a very high performing, lovely sounding amplifier. It is auto-biasing and auto-sensing between 300B and 2A3. Herb Reichert at Stereophile loves his (Gramophone Dreams #74 

For not much more money you could add a Sunvalley SV-S1645D, also from Victor Kung, that uses the 45 tube or with an inexpensive plug-in adapter socket, the the 46 for outputs. Less power than the 2A3 typically produces as a SET, but Oh My! the 45 sound is seductive.

I've both of these amplifiers, having moved way to the other end of the spectrum from my previous D'Agostino Momentum M400 monoblocks, and I am completely happy with the flea powered amps. 

Anyway, just another couple alternatives out many fine amplifiers. Aric is also an excellent possibility and he will build you an amplifier that can switch between 2A3, 45 and 46 if you approach him about it.

Good luck with your journey!

Steve Z

PS: @yaluaka -- Best posts I've read in years. What I want is My-fi, not some else's idea of hi-fi.

Stev eZ

To me this is also a specious point, the idea of accuracy in recorded reproduction. I’m looking for something I like. I don’t want a stereo limited by only sounding good with any particular music or record label. It’s not about accuracy, to me accuracy is anti musical. I want the music I listen to- to be engaging. Accurate is irrelevant, in fact I don’t think it exists. Perhaps an extreme view point. You get into set amps because you want to experience the music not judge the recording.

@yaluaka It appears to me that you are conflating ’accurate’ with ’anti musical’ as emphasized above. That isn’t how its supposed to work; if the amp isn’t musical its also isn’t accurate. IOW if you want the most engaging presentation, the amp will be both musical and accurate. That exists. When the amp is musical but not accurate (as is the case with most SETs) then while it might be engaging, its not as engaging as it could be, because you’re really not hearing the music properly.

For some decades now the solid state community has beat up on tubes by saying that solid state is more accurate. But most of the time those amps were not musical because they made distortion to which the ear is keenly attuned. So those amps had ’low distortion’ but sounded harsh and bright- not at all engaging.

As a designer, once you understand how the ear perceives sound and how that relates to distortion amps make, you can design an amplifier that is both accurate and musically engaging. If you really understand how this works, it doesn’t even have to be a tube amp; the ’sonic signature’ of any amplifier is also its distortion signature. So if you can get a solid state amp to have the same sort of distortion as a tube amp, it will sound like a tube amp. That’s only one of the implications of understanding how this all works.

Put yet another way, there are tube amps that are more engaging than the best SETs, with wider bandwidth (read: more and deeper bass impact) and greater power at the same time.

Its not about judging the recording so much as it is enjoying the music. We’re on the same page with that. It sounds to me as if you’ve been exposed to too many amusical amps that were purported as ’accurate’ when they were not. Harsh and bright to me a far more egregious coloration than the ever-lovin’ 2nd harmonic of tube amps. But if you can get that 2nd harmonic down, you can get more detail, since distortion obscures detail. And you can do this without it being bright.

Again I feel you are missing my point. I am assuming you make amps, funnily enough I make records. So what I care about is musical engagement, this really has nothing to do with accuracy. Why I feel accuracy is anti musical is because you are focused on accuracy. That is not where I am focused. If the amp is accurate and I like the way it sounds great. If it's not accurate (I still really do not believe in this term but I'll use it for this discussion) and I like the way it sounds great as well. The accuracy part is the least of my worries, and for me doesn't enter into the discussion. Just the fact you posit - most single ended triode amps (SET) are not accurate - right then then and there tells me you are not focused on what is important to me, which is how the music sounds. I've learned through making records that distortion is often a musical attribute. I know people don't feel that is the case in the hifi world, but try to get an Al Jackson on Hi Records drum sound without it.

And as for me being exposed to to many amusical amps, I have actually instead been exposed to too many amusical audio fans 😂