High powered single end 300b recommendations

I would like to try a se 300b integrated to find out what the famed sound is like. However, at 86db, my Harbeth S-HL5 are not very efficient. They need more like 25-30W to drive them.


Any recommendations on an 300b amp that will work with these speakers? 

128x128Ag insider logo xs@2xmikedc

This doesn't seem like a good fit. You can get 15-16W from a parallel 300B SET, but unless you listen at very modest volumes and have a fairly small room, an amp like this is probably not going to meet your expectations.

or this one, do not let the ratings fool you, this one will do the job.  


A true SE amp 300B is only 8 wpc , if you go into pure class A around 18wpc 

25 wpc in pure class A solid state like Pass Labs you can operate your Harbeths on .tubes maybe a Ayon Scorpio around 40 wpc in Pentode which is cleaner and better then ultralinear  tubes.

Thank you all for your thoughts.

audioman58 I am actually also looking at an AYON Spirit, which seems like it might be the best of both worlds.

How low do those speakers go in ohms? As others have said, the 300B is usually used as a SET - and then limited to 8-16 wpc. The latter value is seen in parallel configurations. I recall seeing a push pull 300b design but can’t recall the maker. I have a Tektron integrated that uses 2-4 300b’s and gets 16wpc with 4. Highly recommended.  That being said, it also can take 45’s, 350’s, 2A3s, and equivalents.  I got it for the 300b’s, but after some swaping I found I preferred the 45’s. I would listen to a few options before committing to a tube type. 

If you do go the parallel route, keep in mind the cost. A high end 300b tube can get over $1,000. NOS is off the table due the popularity, matching requirement, and stigma behind it. If you can’t individually bias the tubes and need to replace a matched quad, then when 1 tube goes bad you’re in for a $4,000 bill. I have over 60 tube bed across 3 systems. I wish someone had told me that when I started  



I've seen as high as 28 watts in a push/pull 300B amp but the sound of a SET amp is at least as much that it's single ended than the tube choice. SET amps are high in second harmonics due a lot to their topology which compresses the negative half of the input relative to the positive side.

You might check out Manley. They have 300b mono’s you can switch between SE and push pull, 12 and 25 watts, respectively. They have a 300b pre, as well. 

If you want a high powered push pull 300b. Look at a canary  reference 8 300b s in each channel. They have smaller amps as well. Also look at the western  electric  new integrated  amplifier  is is single ended 300b s wired differently so the power doubles up. Both of those recommendations  are not for the faint of heart  nor the empty billfold.



Single ended solid state? Aelph J ? Way better than tubes in my dumb ass opinion. Peace

I’ll say it as no else will 86db speakers and 300b’s are not going to work.  I tried a set 300b amp (8wpc) with 94db speakers and it wasn’t enough. Parallel amp only 16wpc not enough. 300b’s do not sound great when driven much above 50% power so trying to get any volume and dynamics is just not going to be satisfying.  86db is just not efficient enough for a SET.  Maybe an 805 but I’d say that even won’t be enough (around 22wpc).  

your in push pull territory with 86db efficient speakers which is not hi. If you had speakers that were above 98db that would be another situation all together. 

sorry but that’s the reality. 

They are not 300b powered, but Audio Mirror 45w SET mono blocks may be worth a look. Really like mine. No problem driving my 86db speakers. They sound great.

Physics limits the 300b SET to about 8 watts.  

Switching to tubes often means you need to switch speakers.  


@moofoo I’m very impressed with Vlad at AUDIO MIRROR......I may look into his amps because of how musical his Toubadour IV SE DAC is.....that I own.

A 300B SET is going to give you 8-10w.  You can step up to a 300B XLS and get about 13w.  the 520B which is in the same family will get you to 16w.  A parallel SET of 520Bs will get you to about 28w.  

This is simply based on the specs of the tube.  What you can do is get a Push-Pull which will deliver between ~32-40w in power.  A good option would be KR VA830 which runs four 300Bs.  

If you research KR Audio, there is a site KRAudioUSA.com which is run and maintained by someone claiming to be the US Importer for KR that has an axe to grind with KR.  They do not have access to KR and never have.  

It is a good company that makes nice amps.  

You are married to high efficiency speakers if you plan on getting a 8 watt SET or even a PP 300b won’t be enough for a lot of speakers.   

I’ m driving a pair of Forte IV in a small to medium size room and it sounds great but push it too far and it falls apart. It will play moderately loud. I don’t listen loud so for me I’m using probably less than a watt.    These amps are not for people that like to play music loud, that is not what they are all about. 

There is some misunderstanding between amplifier power and speakers sensitivity. The combination of these two parameters plus listening room acoustic characteristics like the Critical Distance give the maximal listening volume. 
There is not direct correlation between speakers bass control, speed and dynamics with amplifier power. 
In many cases it depends more to amplifier schematics and power supply design. For example, in mid size room speakers with 94dB sensitivity can sound better with 845 SET vs 300B SET not because "8 watts is not enough" but because 845 SET has more energy storage in power supply, interstage driver transformer and strong driver tube (for example 300b)  vs weak (for example 6sn7) driver in 300B SET.

Allnic A6000 monoblocks are rated 60w using EML XLS tubes, 4 per side. They also have a toggle for negative feedback and no negative feedback, which helps with more difficult speakers. They sound fantastic if you can find a pair. 

I have Altec 604E speakers in a mid-sized room. The real sensitivity of these speakers is ~97db. I drive it with a 6 watt 300B DIY SET amplifier with EML mesh plate tubes. I did experiments with changing 300B B+ power capacity. I started with 100uF per channel.
Then I went to 350uF electrolytic capacitors per channel. Next time I added 130uF of polypropylene and oil capacitors.
Each time I got very significant improvement in bass control, dynamics, separation, soundstage. The difference was much more significant compared to changing James Audio output transformers to Hashimoto H30 which cost 3-4 times more!
In the end I added another 1600uf of electrolytic CDE capacitors per channel and got another level of clarity, focus and bass control. The same happens when I added capacitors to the driver and input stage B+.
The difference between the initial variant of my amplifier to my amplifier now is huge. It is like its cost has increased 10 times.
I can’t imagine my speakers are capable of such bass performance with any amplifier.
I don’t understand why producers save on power supply capacitors. Why instead of going to the 845, 211 tube models don’t build a good power supply for 300B or 2a3 amplifiers that had much wider bandwidth, less distortions and a lot of other advantages.

Wyetech Labs is worth looking into. They have (2) 300 B mono block amps that are superb and produce about 23 watts per channel  running 2 300B tubes per channel.

I'm using an Aric 300B set amp. My speakers are the Harbeth S-HL5+. I'm also using a pair of Rel T/9x subwoofers. My room is 12 x 19 and moderately treated. A Bricasti M3 feeds directly into the amp. My listening distance from the center of the speakers is 8'. I usually listen to Jazz and some basic rock from the 60's- 90's. The volume setting on the Bricastic is usually -20 to -25. This typically yields a volume of 70-80 decibels from my listening position. I have pushed the amp into the 90 decibel range on a rare occasion and not experienced any clipping. I live in Maine if you want to audition my system.

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one other consideration for you if you go to a Parallel or Push Pull 300b you will be replacing 4-8 300b's tubes when they go, worth it? they run what around $250 each these days for average ones. re-tubing gets costly fast. 

I had a home built BeePree 300B preamp and NAIM NAP100 power amplifier. That combination gave me the 300B sound and SS power to drive my Focal speakers. Not too expensive and very pleasant to listen to. Such a combination was mentioned earlier by Snowstorm above to use a 300B preamp and solid state power amp to get the best of both worlds.

@rooze has it ... the Allnic A-6000 are 60W a side with 4 x 300BXLS in parallel, and sound incredible, in the top 0.1% of all amps in any category. Best I have ever heard vs. very costly others. The soft start means the power tubes will last a decade.

@glennewdick these 300BXLS tubes are more like $750 each, yet not to worry, I have my amps on 10-12 hours a day usually 7 days a week for 3 years. And with only 30% loss in tube life and 0% loss in power or tone.


Sadly for your needs @mikedc no integrated will get there.

As an aside, I am also wondering if all Class A amplifiers generate a lot of heat, include those of low output wattage.

@mikedc you’ve received a lot of good advice up above. And some good solutions proposed. I’d like to suggest an intermediate step before you go shopping for new speakers or a new 300B amplifier.

I humbly suggest you download (if you haven’t already done so) an app for your phone like Decibel X PRO that will allow you to measure what sound pressure levels you do most of your listening at. This will provide some empirical data (yes I appreciate that it might not be as accurate as it would be if you were using a calibrated microphone, etc. but it will get you started) so you know approximately how much power you are using to listen to your music in your listening room on your speakers. The version of Decibel X PRO I use costs a couple of bucks, but I find it very convenient and use it frequently. I expect there are alternatives out there that would also do the job.

Personally I would seldom be listening at 86dB. That’s just me, in my listening room. But for me, 86dB is LOUD. Yes, I might sometimes feel like cranking it up above that level but I find that most of my listening is at a lower and more comfortable level. You need to find out how loud you’re actually listening.

I bring up the 86dB because you said your speakers are 86dB efficient. That is to say, if I understand you correctly, that they will produce 86dB with one watt at one meter. Yes I appreciate that I am making some generalizations here and that nobody sits around listening to pink noise... But you might find that you could dip your toes into the 300B water without changing speakers or buying an expensive parallel single ended or push/pull 300B amp. You might be surprised at how loud your speakers will play with just a few watts.

Yes, of course, more efficient speakers, like a pair of Klipsch speakers, or vintage Altec VOTT or whatever would be a better match for a "low powered" 300B amp. But I’m simply trying to suggest an action that will allow you to have a better idea how much power you need before you go out and buy an expensive amp or change your speakers.

BTW, I no longer consider an 8 watt amplifier to be low powered. I’m now routinely listening to my 94dB efficient speakers with just 1.5 watts. It sounds wonderful. Of course, my music, my room, my tastes. And YMMV.

If you like to listen Jimi Hendrix, or Motorhead or Mahler at high levels (say, at 95 - 105dB) then 8 watts isn’t going to do it for you with your current speakers. But if you’re listening to a wide variety of music at lower volumes then you might be surprised.

Another comment. There are many alternatives to SET 300B amplifiers. And the devil is in the details. And I’m sure there are crappy SET 300B amplifiers out there. Just like there are probably compromised PP 300B and PSE 300B amplifiers. But there’s a reason people consider SET amplifiers special. It’s that first watt. Maybe the first couple of watts. And the simplicity of a well executed SET circuit. When you start making the design more complicated to produce more power you are going into a different direction and there are many wonderful alternatives to the 300B that can sound great. Another way to say this is to say that the 300B is simply one alternative tube. And a SET design is simply one approach. There are other wonderful triodes out there and some of them make a lot of power and can sound great.

One more comment. All equipment is a compromise. Cost, size, appearance, power, efficiency, "wife acceptance", etc. The key is synergy. That’s where all the accepted wisdom and advice reach the limit of their usefulness. Your direct experience as you go forward will be much more useful in this regard than anything you read on these forums. Good luck in your endeavors.

Why 300B? I have a pair of Modded Altec Lansing 1570B, each mono block using (2) 811A triodes with NOS Peerless transformers. These mono’s are making 165 watts and sound incredible.

@markusthenaimnut thanks for such a thoughtful and educating reply.

And to all who have replied, thanks for taking the time to share your thoughts.

Just this morning I was thinking that perhaps it was time to take a step back  and reconsider the basics. I even repositioned my speakers which opened them up a bit more. 


Did you ever measure how loud your normal listening volume is? If so, what did you find out?