The Audio Gods are tough but fair-Have you had the "Curse of the 300B" ?

These amps can really pull you in to hear the singer. The voice instrument is so spot on it can provide moments of disillusionment. For example, I've always preferred Sam Cooke's Live at the Harlem Square Club over Live at the Coppa.  The former is way more free and pushes the R&B needle.  It's musical and soulful.  On my 300B setup I agree with that but I also can put Live at the Copa on and be drawn in... in so much that I start enjoying that album as much as Harlem Square. My attention gets focused on the music and not that this isn't my favorite Sam Cooke album.  And I start hearing and feeling things in the vocals that weren't present before. It's wonderful in the truest sense. 

The 300B SET also delivers smaller group instrumentals like no other.  Drums in the jazz, acoustic/folk settings are sublime.  You really identify the drum skins. You do this sonically more than viscerally.  It is, however, intoxicating.  

When done right these amps can be captivating.  But the 300B mistress is not without its issues.  

-You have to mate it with more sensitive speakers.  This is huge.  You are no longer looking at the lion's share of state of the art loudspeaker reviews.  No. You are searching for sensitive, efficient speakers because the 300B runs out of gas real quickly. 
-You have few choices in amps, 
-You have few choices in tubes and they get really expensive for the 'premium' makes.
-You are likely listening at below moderate to moderate volumes. 
-You may keep a second system to use outside of 300B time. 

When I go back to push pull, or even solid state, I immediately appreciate the power and increased visceral impact.  My attention, however, gets more easily lost, and while they don't sound "bad", I lose the clear window into pieces of the performance.  Subtle nuances of how the singer's voice has personality arising out of the phrasing and tone of the vocal.  Instruments with the 300B sound more "instrumenty".  I don't consider any of what's lost when switching to push pull to be hyper detail or analytic.  Instead, it's characteristics of the sound that aren't there leaving less of the inherent personality of whatever sound is being reproduced--vocal, instrument, or the room in which the performance is taking place.

And so I've done things with my system to help it when it's in 300B mode and push pull mode.  For 300B, I added an REL subwoofer and a second Sumiko I had laying around.  I use those to load the room and expand low end but increase soundstage and make things sound bigger with few watts.  For the push pull setup, I've got the input source all tube whether digital or vinyl.  

This leaves me with the feeling that the Audio Gods are tough but fair.  It's hard to have it all with SET or PP.  Nonetheless, my mind seems made up that it seems easier to work within the 300B setup to make it better as opposed to the push pull. 

As a total aside, I am not the audiophile sage that many are on this forum or out in the audiophile-wild.  I will say with confidence though that if you love hifi you owe it to yourself to spend a month with a SET amp coupled with efficient speakers. 
More "instrumenty" .I like it:)I understand perfectly what you mean.Before I bought my current(and last) amp I was torn between going with an SET or Push Pull.I ended up with one that can be switched from ultralinear to push pull built by Aric Audio.Perfect for those of us that can't make a decision:)
I'm definitely cursed to never to be happy with solid-state again.My entire system is tubed also.
I'm going to check out Aric Audio--for curiosity's sake!

Yes, and I'll say I'm probably breaking some SET gospel rules by using the REL in the system.  I have it set so low it seamlessly integrates and provides staging, depth and relaxes things nicely.  
I use my SET 300B to drive my 94db Tannoy HPD 315 custom built speakers, and really love the sound, so I get what you are saying. For everyday listening and video sound (multi-channel), a 500 Wpc Class D amp and two subwoofers.

When using the 300B, it is driven by a Transcendent Sounds Grounded Grid preamp (tubed), and no subs (I'm too lazy go to the trouble of switching the cables over to use the subs).

Although I love the sound as it is, I've been bitten by the 845 tube bug, and I'm planning on moving in that direction. That should help in the power situation, and I understand in many other areas of sound quality. Besides, I love Big Tubes!

Listen however and to whatever puts you in that zone:)Aric is a very nice "mad scientist" and does custom builds too. I enjoy reading about the smaller companies,visiting their websites,blogs, and FB pages.
Sorry to get off topic!Hopefully some more 300B will chime in:)
You’re all preaching to the choir here. 

After years and and years of owning many fine amps I’ve settled on my upgraded Aric Audio 300B SET. There’s a purity to the sound of a well implemented SET that can’t be matched in my estimation. Obviously proper speaker matching is essential and with the right speakers the sound is magical. 

300B sound is golden but God make sure you truly work for it.   

Great things come in small quantity ... 300B is like that don't get a lot, but whatever you get, is divine that cannot be matched.

Hope this helps.
Hi jbhiller,
Thanks for posting your happy 300b experiences. As you can see from the replies you aren’t alone. As noted, no amplifier type, design or topology is without some inherent compromise or shortcoming. In the end we choose what suits us best. "Instrumenty" I know just what you mean 😊. There are for certain very fine sounding solid state and push pull tube amplifiers and I have owned some myself.

When I acquired my Coincident Frankenstein 300b mono blocks and powered them up it took about 10 seconds to realize this was the sound I’d been yearning for. Things only improved as the amplifier burned_in. This was 9 1/2 years ago and my admiration and happiness has only grown. It does many things well but reproduction of human vocals and instruments was the best I’ve heard. Just so pure, connecting and realistic. It has been an absolute joy and now going on 10 years of ownership these amplifiers are a permanent fixture in my system.Needless to say all 300b SET amplifiers aren’t created equally. However if one gets a well implemented good quality amp you’ll be rewarded with music reproduced with strong emotional involvement, excellent tonality, beautiful nuance and realism. This is my listening experience.
I like the constraints imposed by the 300b gods. Otherwise, the number of options in terms of speakers and amplifiers and the possible combinations becomes overwhelming. 

I started with high efficiency speakers with built-in subwoofers (Zu Definitions. . . now in their 4th iteration). Then I went through lower power SET amplifiers (45, 2a3) before settling on a good 300b SET (Ancient Audio). Finally, as suggested, I tried different 300b tubes (Shuguang, Psvane, Sophia) before settling on Takatsuki. 

Even this limited journey took years. But I am content and have made no changes in the last 8-9 years with no plans to tinker in the future.

Actually, I am impressed by the number of available 300b tubes with new versions every year.
Hi Gary,
You raised a point I forgot to mention, you re right, there is no shortage of 300b tubes available. Through a combination of buying and getting generous loans of tubes I've heard 10 or 11 different 300bs in my SET amplifier. Also there is no shortage of good quality 300b amplifiers currently available. The SET circuits are quite simple the major keys for sucess are output transformer and power supply quality. 
"The Audio Gods are" subjective - to each his own.  300B talents are limited to a small set of speakers as it cannot drive 99% of the speakers out there.  
-i would definitely agree with "subjectivity" and "to each his own". I find the 300b has a few limitations but by no means debilitating. In regard to speaker selection the sensitivity and probably more so the load impedance curves are necessary considerations. . In my experience there are a good number of viable candidates. One can find them with the proper (and motivated) search.
The Audio Gods do make you work for it!  Also, so well said to say that "you don't get much but what you do get is ...GREAT!"
While I definitely agree with "300B talents are limited to a small set of speakers as it cannot drive 99% of the speakers out there," I also find the constraints useful. No different from designing a house from scratch with no limitations other than budget and size. For me, anyway, there are enough speakers that occupy that 1%. The only issue is that most good high efficiency speakers are expensive. 
I’ll be the friendly dissenter as I do not accept the premise that 99% of speakers available are incompatible with a 300b SET amplifier. That ’may be true for the 1 watt 45 tube . A friend uses 3.5 watt 2A3 SET mono blocks and the list of speakers he has found to pair with his amplifier is surprisingly impressive. Wilson,Magico, Vandersteen and Maggie’s? No. However there are ample choices that are suitable. Many are from high quality but small/lesser known companies. The 300b SET isn’t an universal amplifier for any and all aplications. Nor is it as narrowly limited as some suggest.
So much great intel here.  Thank you all!  I really appreciate the views, thoughts and opinions.  This is what it's all about. 

Among the reasons I think every audiophile should try a 300B SET, is that it really allows you to hear recordings for what they are/were supposed to be.  I can go back through my musical ancestry and find albums I loved but now (or recent in PP or SS) thought weren't that well done, and now I can hear them with virgin ears.  It's such a blessing. 

At times it becomes spooky.  I think that I could die here streaming albums and songs forever.  I recently went back and listened to all the 45 records I bought as a kid in the late 1970s and early 1980s.  I did this entirely through Tidal HiFi with all tube DAC.  The 300B took me back to my youth--to hear those songs anew.  If I do it with my PP or SS setups the songs get lost as pure nostalgia, nothing more, nothing less. 

The 300B with all tube inputs (vinyl or digital) is so refreshing.  It's like so much is washed away, leaving pure signal.  That's the best I can do. 
Not so long ago, I have decided to try the all tube set up. It was a slow and step by step journey, where I used the 'usual' ss names, like small and big Krells, than Pathos hybrid and than all Burmester set up (which is the ss that I like the most) always with Souns Faber speakers (not really tube friendly)

Than I decided to try small monitors from Franco Serblin, which have low sensitivity, but rather stable impendance of 7,9 ohm at lowest point.
Currently I am using paralell single ended amp in A class (tetrode) and premap from Unison Research with power of 30w.

I am thinking of trying some bigger set (like Cary 805) or perhaps Vac push pull with 300b tube.
Does anyone have experinece with 300b in pp configuration in comparation with se?
Is it possible to maintain that 'famous' sound of 300b in pp?
Alexatpos512: I suggest that you speak with Gary Dews of Border Patrol. He makes 300b amplifiers in all three configurations: SET, PSET, and PP. I have found him knowledgeable and approachable. 

I would also suggest to contact Aric from Aric Audio. He is super knowledgeable with 300B design and possibly accommodate you with pretty much any customization available under the sun. 

I am in process of trying his newest prototype of 300B with SE and parallel designed amp all in one chassis. The amp has a complement of 300B x 2, EL84 x 2, OA3 x 2 and 5U4GB x 1. The amp is capable of 8wpc in SE mode or 16wpc in parallel configuration. 
Folks, this discussion is brilliant. Thank you for all the references. 

Aric looks super legit. 
Aric [of Aric Audio] looks super legit.

He is. Great guy as well.
Ignoring the fact that you and your friend may have completely different systems , can you offer some personal  listening impressions between the 300B and 2A3 ?
Theres no doubt that any of the 300B topologies can produce beautiful music but which is best for you will depend upon your system/room requirements and your listening preferences.

I had Arics 300B SET and 300B PP amps side by side in my listening room and while the PP was a very good sounding amp it lacked the purity of the SET that I can’t live without. Others with different musical preferences than mine might prefer the power of the PP more but with the jazz and acoustical music that I normally listen to the 300B SET is magical. 

Ive talked to Aric and Gary of Border Patrol and they both agree with my assessment that the SET has a degree of purity and refinement that neither the PSET or PP can match but obviously they have their place, especially with less efficient speakers or those that want more power. 

I’ve worked with Aric through five different builds now and I can’t say enough for his expertise, professionalism, character and willingness to create the best possible product for your needs. 

Thanks for sharing your experience with 300B SET. I can hardly wait to hear the purity of 300B SET in my setup. My Canterbury’s are 96db so I should be okay with 8wpc. I got both Sophia Electric 300B Mesh and Royal Princess so it will be interesting to hear the differences between the two tubes.

Would you mind sharing which 300B tubes you’re using with SET’s? And are you using mono’s or stereo amps?

I would like to try EML 300B-XLS and Takatsuki TA-300B once I am settle with my amp selection.

I also echo your experience with Aric, great guy.
Hi Lalit,

My Aric 300B SET is a stereo amp that Aric upgraded with Hashimoto transformers, Duelund coupling caps and WBT Nextgen binding posts and rca inputs. I’m using the EML XLS 300B tubes. 

Aric will soon make my amp into monoblocks with two external power supplies and C3M driver tubes with an interstage transformer. Fun times ahead!!

Good luck with your 300B audition. 
I will read this when i have week to spare.
There's a pretty good article by Herb Reichert in the April 2019 issue of Stereophile re his early experience with 300B tubes and more recent experience with the EleKit TU 8600R integrated amp kit (300b)
That’s my amp!  Can’t wait to read it 
jb - you'll be happy when you read it
Charles, please ignore my question to you above about impressions between the 2A3 & 300B, I came across a 2013 thread where you and a couple of others provided someone else feedback on the same question. Thanks
facten, I just read the review. It is spot on. Here’s how.

The Elekit 300B kit (with upgrades) does sound clear, like "water" as Herb Reichert says. Compared to my Primaluna Dialogue HP it sounds cleaner and has a special presence. The Primaluna is a great amp indeed, but it sounds fuzzier than the Elekit. The Elekit, despite having 1/4 of the wattage or even less, sounds open and unforced. The Primaluna sounds more aggressive and not in a bright way but like the sound is being pushed at me.

The Elekit is really simple to build. I think Herb Reicher was a touch conservative in describing the effort in building the kit--just to be safe. It’s actually super easy and the directions are foolproof. Even if you’ve never soldered you could just buy a spare breadboard and some cheap resistors, watch a Youtube video on soldering and you’re good.

The only downside of the Elekit is that I wish it had 2 sets of single ended/RCA inputs. Also, it would be sweet if there were instructions on how to formally bypass the volume attenuator so you could run it as an amp alone and then build two and do monoblocks. But that being said, I have 98dB sensitive speakers and I can get things rocking in a big for me room (15 x 23 x 10’ high).
If any readers want an overview of SE vs PP, this is the best I’ve ever found. It’s clear and interesting:

Yes, I'm in the SET cult too.  I have multiple SET-ups, all driving various Klipsch heritage speakers.  My main set is Cary 300B monoblocks driving Chorus speakers with a tube pre and mostly vinyl sourcing.  But my second, and actually preferred set, is Bottlehead 45 monos driving La Scalas.  Both are louder than I'd ever need, and obviously the La Scalas are even more efficient, but to my ears the 45 tube is slightly more detailed and musical than the 300b, which I consider a "rock-n-roll" tube.  One day I'll experiment more with tube rolling these amps....
@glow_worm That is one of the best articles out there in that it explains clearly what is going on in a single-ended amplifier that contributes to what many of us hear as its "magic". Of course we can also see why push pull is so efficient. I read that article a few years ago and it is inspirational to me when I'm designing an amplifier. Of course, like all things audio- it can become addictive! So true to the audiophile "bug" I will be playing with some large transmitter tubes next (211/845). I also wanted to thank those that made mention of Aric Audio in this thread for the kind words :-)

Best regards, Aric
I get very satisfactory sound levels with my 300b monoblocks driving Proac 1SC, (86 dB./1W/1M),  by biamping below 70 hz. To a pair of servo subs. 
Marchand 4th order passive xovers, drive a pair of Yamaha servo subs .
300B is addicting to listen to.
Room is 24 by 12 by 8 high.
Diy ,Je labs 300B monoblocks .
Relieving the main speakers from reproducing bass, improves efficiency a great deal, while maintaining most of the charachter or the Proacs.
Very happy .
Here is another link you all may find interesting. Eddy's article covered a good deal of the basics, but one thing he really didn't go into is how the amplifier interacts with the loudspeaker.

Since SETs run zero feedback for the most part, this is pretty important! So here's the link:

Also FWIW, Eddy didn't cover the issue of distortion completely. One important thing he left out is that SETs have distortion that linearly decreases to measurable at lower power levels- this is the source of that 'inner detail' you read about in them so often. Most push pull amps don't do that; below a certain power level their distortion actually increases. But this is not true of **all** push pull amps; it is possible to build a push pull amp that shares the character of decreasing distortion to measurable just like SETs have.
Interesting reading about these amps!
However I still haven't found my stereo tube amp for my 101 dB / 4Ω horns, even theoretically.
Question: would 300b amplifiers work with my ~93dB efficient JBL 4430 studio monitors? Or do I need something more efficient than that?
Hi Mark, In my opinion Yes it would. However this depends on how loud you listen and what type of music you listen to. For jazz, acoustical or any analog music you will achieve healthy volume levels. If on the other hand you listen to bass heavy reggae/ska at loud volume levels and like to pressurize the room with bass- then the 300B will start to run out of steam. I listen to all types of music- including what's mentioned above. With my 97 db speakers the 300B has plenty or current and headroom to achieve very loud levels but I am able to make them clip if I am pushing heavy rock music loudly. In that case, I really like my KT150 single ended or perhaps my EL34 push pull amplifier. However for all music- the 300B single ended sounds better when driven within its power limitations. I hope this helps, Aric
Yes, thanks. Those comments are helpful. I'm preparing to move, and in my new listening room I should have room for two systems (since my wife objects to having the rather large JBLs in the living room).  The write-up above and all the comments are very compelling.
I have a $120,000 system in a dedicated listening room and it is amazing. 
My second system, in my living room, cost $20,000 and is comprised of a Cary 300 SEI integrated 300 B tube amp with Wilson Benesch Arc Monitors and an REL S/3  Subwoofer. I'm using a Prima Luna tube CD Player and speaker cables and interconnects are Nordost. I can honestly say that the 300B set up is every bit as enjoyable as the big system which cost 6 times more money. Both systems provide a completely different listening concept but the 300 B outfit is so sweet that I could live with it alone if I could not afford both systems! I have been buying and selling stereo equipment for 45 years and the 300 B is very special to say the least.
Question: would 300b amplifiers work with my ~93dB efficient JBL 4430 studio monitors? Or do I need something more efficient than that?
Unless you are playing the speakers nearfield you either will need more power or more efficient speakers.
Again, an SET is best used when the maximum volume attained does not used more than about 20-25% of full power. Otherwise the amplifier starts making more higher ordered harmonics. If you've ever wondered why SETs are known for being so much more 'dynamic' than their low power would suggest, this is why: Those higher ordered harmonics are used by the ear to sense sound pressure and since music has a great deal of transients, the loudness cues (distortion harmonics) initially show up on the transients as you turn up the volume. This sounds to the ear is if its more dynamic but in reality its just distortion. Once you are aware of this fact, its also easier to hear that such is the case, so I may have ruinied it for you if this is how you use your SET.
Own very efficient speakers, 94db+ and be prepared to listen at a lower volume. This is how I prefer to listen, and brings me as close as anything to audio-nirvana. 
Same here, own 96db efficient speakers, paired with two REL subs. My listening level is never more than 65-70db in a room measuring 15’D x 25’W. That’s plenty loud for me 😊
My listening level is never more than 65-70db in a room measuring 15’D x 25’W. That’s plenty loud for me 😊
96dB is at the upper end of moderate efficiency. You might think its playing loud enough, but if you ran an amplifier that was making less higher ordered harmonic distortion, you might not think so. If you really want to hear what a 300b can do, try a speaker with +101 dB sometime!
Thanks for the advice but I am perfectly happy with my current setup. I have no desire to upgrade or make changes anytime soon.
Monostereo magazine looks like it will be doing a review at some point on these 300B mono blocks - 50wpc class A 

Here's the Thrax webpage itself should you be interested in seeing them
Sophia Electric has a number of 300B amps and options and they all sound really good. I have used them with Tannoy's and Wilson Beseech Curves. 
Thanks for providing the link regarding the Thrax 300b amplifier, this needless to say is a beast as it weighs 120 pounds. I suspect that the transformers, chokes and power supply are massive and yet of outstanding quality. This is an (it seems) all out state of the art effort. 50 watts pure class A push poll topology. I wonder how much nuance, inner detail and intimacy of a SET (single 300b) it will capture/preserve? No doubt it will have impressive authority, dynamics and musical power with an appropriate speaker. I look forward to the review. IMHO what SET does best and sets it apart from other topologies is tone, purity, intimacy and emotional connection with music listening.
I wonder how many here are willing to shell out 68K euros for Thrax 300B mono’s. I am sure it’s every bit impressive as it appears on the paper. 

Hear you on the cost, I just passed it along as I had never seen a 300B at 50wpc and didn't know if anyone else had
Canary audio has made a 50 W 300b amplifier for quite a few years now. Allnic I believe alSo currently builds a 50 W 300b. At one time VAC produced  140 watt 300b mono blocks with eight of these tubes per channel (16 300bs total !!!). I am glad that I have found much contentment with a single tube 300b per channel SET 😊. Replacing multiple 300bs can get expensive in a hurry.