What tube amp for Harbeth 40.1

I am looking for a tube amp for Harbeth 40.1.  I know many suggest SS amp such as Accuphase, Luxman, Hegel, McIntosh ... etc for Harbeth, but I decided to keep it with tube.  I also don’t think I need a lot of power.  I currently have a 8W custom built 300B and had a 18W Almarro 318B, and to me, they sound fine.  However, I think more power will help, and I never know what I missed until I try it out.  Having said that, I don’t think I need crazy power.  Anything 30-80W is good enough for me.  I am 3m away from the speakers, listen to Jazz at avg 83dB.

i have the following short list:
1) PrimaLuna Evo 400 integrated
2) Leben CS600X 
3) Linear Tube Audio Z40

Which one do people like with Harbeth?  Any other suggestion?

Among all qualities, I value holographic presentation the most.  I really like the feeling as if the singer is floating in front of me, if you know what I mean.  And my current 300B do pretty well in this regards, and I read this is what SET amps are good at.  Will I be disappointed with the above?
If you don’t listen to rock or demanding music which has lots of transients and burst of dynamics, or music with a lot of deep thumping bass lines, a low to moderate powered amp would be fine. Perhaps that is the reason you find the flea-powered Almarro amp too be sufficient for the 40.1. What you need is a tube amp that is able to bring the clarity and detail from recordings at low to moderate levels, music which doesn’t have a lot of dynamic swings or demanding bass.

A friend uses the Leben CS-600 on the 40.1 and the midrange to highs show higher levels of clarity and detail. But bass does not too deep or show the same level of punch as the solid state equivalents. It depends on what you want to achieve with your system, apart from musical preference. If you want holographic or 3-dimensional sort of presentation (I like this too), do try the more powerful tube designs if possible. I know most people will say power or current is not important for Harbeth but my experience tells me otherwise. I have used many solid state amps with the Harbeth SHL5+ throughout the years.

In summary, you would do fine with flea powered tube amps with the 40.1s or any Harbeth for that matter if the music isn't too demanding or you mainly listen to mellow stuff. For wider music genres and balance, an amp that is able to provide the dynamic swings at all volume levels would be more appropriate.
Were it me I would go with the LTA. 
@ryder Yes, I only listen to Jazz in low to medium volume averaging at 82dB.  I think a tube amp with is good for me.  My goal is to find something with more power so to improve the bass and sound, but won’t lose the 3D, holographic sound.

@mapman Do you have experience with z40?  I did some research on LTA, their ZOTL10 has very good reviews.  Their preamp got very good reviews too.  But I haven’t tried any OTL amps. I read someone said a well executed OTL gives more dynamics and lively music.  
But cost is a concern too.  The PrimaLuna are the cheapest out of the three.  

There is also a Audio Research VSI60 on sale locally for much cheaper than those three.
My friend has been driving his 40.2s with a Line Magnetic Audio LM-518IA. It's magical. 
Yes, I read good reviews on Line Magnetic especially the 219ia.  But I don’t feel comfortable with the super hot 845 tube.  One of the reason I sold my Almarro 318b is because of the heat from the 6c33c.  
That is actually a question.  Does any of those amps I short listed run super hot?
All tubes run really hot, the more power the more heat dissipation.  I love Border Patrol with Harbeths but that is a lot of tubes.
You could consider a hybrid amp?  Tube for gain stage but SS output.  That will run cooler (rogue sphinx for sale here).  Class A amps are hot too.
Gte I have heard the LTA amps at shows.  The ZOTL design sounds pretty much just as advertised and related in reviews. 
PL or cayin both Top Dawgs. 
All tube amps do not run hot. The LTA ZOTL amps by design generate far less heat than traditional tube amps and the tubes last far longer. They are perhaps the most practical tube amps for listeners who may be hesitant to go with tubes. In addition, the LTA amps present as much more powerful than their specs would suggest with lots of drive and dynamic capability. That said, in my experience Harbeths like power so get a ZOTL 40 Reference for now which gives you the ability to pick up a second down the road to run monos which will be plenty of juice. 
That is actually a question.  Does any of those amps I short listed run super hot?

I ~~~HATE~~~ SET amps, 
Extremely limited as to what speaker you can choose, not to mention to my ears they sound anemic. 
Push Pull are King of Tubes.
I havea  Defy7, has 12 6550's. I feared the heat would cook my 10x12 room, not so, 
Not sure how hot Cayin/PL run. 
I had a  small EL34 Cayin, was not hot at all,. But the bigger KT88's, , maybe. 
Your ~~super hot~~~ no I do not think either lab meets that criteria of ~~super~~
There is a pair of PL monos  on ebay starting at $1600, might not be a  bad idea throw ina  bid..But honestly I am a  bigger fan of Cayin vs PL.

Do you want integrated or power?
I was thinking this model:
A lot of their products have fairly similar model numbers.
Tubes are not run anywhere near their limit and will effectively last almost indefinitely.
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+1 on the recommendations for an OTL design or Line Magnetic.  You're gonna need a bit of grunt with tubes to get those Harbeths to sound lively.  I think a LM 805ia may be a good choice with its' 48w of Class A SET and 300b tubes possibly giving you exactly what you seek.

I noted J.A.'s comments when he measured the 40.1 in Stereophile:

My estimate of the big Harbeth's voltage sensitivity on its tweeter axis was 84.5dB(B)/2.83V/m, which is within experimental error of the specified 85dB/2.83V/m. This is lower than average, and suggests that a goodly powerful amplifier will be needed to achieve high playback levels. (I note that AD's 10W Shindo amplifier didn't cut it.)

Audio Reveal Second is a great match with these speakers..
@twoleftears i am thinking an integrated.  It is the Z40.  Budget is a concern, bought too many gears within this year already.

@elevick yes, I considered hybrid and seriously look into McIntosh MA252.  I always want a piece of McIntosh, but have been using efficient speakers.  Initially, I think this is my chance to buy a McIntosh with 40.1.  But after doing some research, I am not sure.  MCs are expensive, and it seems a big part goes to the brand.  The MA252 is more affordable, but then some comments says it clips (with the light turns from green to orange) easily even at normal volume.  I don’t think volume is a concern for me, but it seems the quality of the product is not as good as their more expensive amps.  It seems for the money, I can get more from other brands.

And my budget is $4000 for used equipments.
@squeak_king_77Thanks for your feedback on Leben.  Based on that, it seems the CS600x may not be suitable for me.  For example, compared to the Almarro and my custom built 300B, I feel the Almarro is more “linear”.  I don’t know if this is the right term.  I feel my 300B is a bit more dynamic, more engaging ... hard to tell exactly what are the differences, it is more a feeling and impression.

I heard good things about atma-sphere.  But  ... it takes many tubes, it would add to the cost.  I am not sure how expensive are the tubes ... 
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Probably a long shot.  Anyone has experience with Luxman mq-60?  It is a vintage in 1970s.  It is a push-pull in triode mode.  It originally use 50CA10, but I am going to change it to 6L6.  It outputs 30W.  I know 30W is likely not enough, but just think to try based on the price tag.
 But  ... it takes many tubes, it would add to the cost.  I am not sure how expensive are the tubes ...
@gte357s the power tubes are about 27.00 each. In a lot of cases a full set of them for our amps is less than one tube for some SETs!

You will need some power for this speaker. It appears to have a benign impedance curve but if the sensitivity number is real, a 60 watts will be a lot better than 20! A lot depends on how conservative Harbeth is about their numbers- As I recall they are pretty conservative so the speaker is probably easier to drive than the specs suggest. 
I would look for used VTLs.  I sold a pair of MB-185s last year that would have fit your budget.  They would be a brilliant pairing and give you a little more oomph which the Harbeth's like.  
Look for Tsakadiris tube amps, they are well made and very very musical , they have many accolades for audiophile that loves music,and emotions, I do own the Apollon monoblock, their stuff is very dynamic and versatile, they have 70 watt, mine are 150w using kt150, If you are looking for a tube amp, that will give you music and dynamics, this amp are the one ,they have different models, Toska audio here in Illinois carries them...my source for this amps SME 10 tt, Icon tube ps3, maRantz sacd, Schiit Gumby Dac, and Tellurium q cables...preamp Krell
Have you seen the video where and where A. Shaw demonstrates that the big Harbeths easily pull 500W on transients?

No offense, but you're cheating yourself using tubes of almost any power level with these speakers. They need lots of power, and are designed for a low-Zout amplifier.

These speakers, while having many great qualities, are not capable of anything close to lifelike dynamics even when given appropriate power. When they are not, they sound especially flat and dull.
Having heard the 40.2s with a 48 watt per channel integrated, I can attest to the fact that they were the exact opposite of "especially flat and dull".
I also don’t think the power makes it flat or dull.  It is more depending on the circuit.  I have two 300B amp, one is 11W and one is 8W.  Tested on my Spatial Audio X5, the 8W one sounds more dynamic. 
Tested on my Spatial Audio X5, the 8W one sounds more dynamic.
Naturally- SETs make distortion in such a way that the distortion sounds like 'dynamics' to our ears. But I get your point- we have a lot of Harbeth owners as customers and somehow they seem to work quite well together.
Try out the Vinni Rossi Lio
Excellent amp that will solve your problem

I have a PrimaLuna Evo 400 Integrated for the past three months. It is an incredible amp. 38w Triode and 70w Ultralinear. And if you need more power, you can roll tubes (KT88, KT120 and KT150) with the auto bias, no calibration required. I listen to 50's and 60's jazz and it is extremely sweet, detailed and creates a very special atmosphere.
I'm upgrading my whole system to Audionote (amp, speakers, dac, etc) so the amp is available if you are interested.
If those Harbeth need power , Tsakadiris apollon mono willl work beautifully, they run my hungry power Andra speakers effortlessly,they are 150 watt. Few powerful amps I heard has the musical virtue like the Apollon.they are only 4K.
A few reminders may be necessary before making the jump to tubes.

1 Alan Shaw himself is unlikely to recommend a tube amp.

@paulfolbrecht asked earlier,

'Have you seen the video where and where A. Shaw demonstrates that the big Harbeths easily pull 500W on transients?'

In that video Shaw himself was shocked at just how much current his M40 speakers were drawing on  certain transients. Yes, a peak of 750 watts!

[Not recommended viewing for anyone with low power tube and low efficiency speakers].

How Much Amplifier Power Do I Really Need?


2 No tube amp is likely to have the same dramatic bass punch as a powerful SS amp will. That's not why people buy tube amps.

Having got that out of the way, if you still want a tube amp then I'd also suggest the Leben CS600. 

There are many accounts of satisfied owners using them with Harbeth speakers. See the Harbeth forum for more details.

Furthermore, the Leben amp is such a gorgeous work of art in itself that it should always bring you pleasure before you even switch it on.
No tube amp is likely to have the same dramatic bass punch as a powerful SS amp will. That's not why people buy tube amps.
These days most solid state amps have output impedances so low that they overdamp the loudspeaker; no speaker made needs more than 20:1 damping factor and many work better with less. An overdamped speaker exhibits a coloration that many call 'tight bass'. Yes, there is some punch but you really don't get much in the way of definition. Tight bass is something you hear in stereos quite a bit but its really hard to find in real life. In a nutshell in their zeal to create the perfect voltage source, amplifier designers far outstripped speaker designs in this regard!
That is a cool video! Interestingly when he actually played a recorded song as opposed to a test CD, the max power peaked at like 30 watts. So as they said you really have to take into account distance, listening levels, types of music you like to play and then match an amp to those personal characteristics.

Why should that rule out a carefully selected tube amp? Well...

Well yes on the HARBETH private forum (HUG), they humiliate anyone who wants to go tube. Basically the message is don’t need to spend a lot on amps, just buy the most watts you can even Class D over tubes. I bucked that trend and have the 40.2 Annies with the LTA z40 and it sounds glorious to me but what do I know...i listen with the grilles off, another big no no you will get ostracized over. Probably going to LTA Ref monoblocks which will get me almost 100 wpc at 6 ohms the minimum impedance.
I'm running my Harbeth C7ES with an Aric Audio Transcend Push Pull amp with either KT88 or KT150 tubes(45 and 65watts).I also tried them with a pair of QuickSilver mid monos w/EL34,KT88,and KT150.The KT150s have the biggest liveliest sound,the 88s are good too.As expected,the EL34s run out of steam rather quickly.Personally,I prefer the tube amps over the 120 watt ss CJ amp I tried also.
IMHO the Harbeth 'house sound' puts you a few rows back as opposed to front row as far as dynamic swing and transients whether ss or tube.If I were in the market I would give one of the LTA amps a try.I have one of their preamps that I am extremely happy with.Just my two cents:-)
Any Harbeth that I have owned sounded great with Quicksilver amps!!
Thanks for all the replies.  A lot of good suggestions.  I picked up a McIntosh MC275 IV yesterday.  The reason is that it is a local sale, the price is right, and it has a gain control.  I don’t have fund to buy a preamp now, so, this is a big plus.  I connect my source directly into it.  The McIntosh is more readily available in the used market also.  But definitely will try those other suggestions when something comes up.  I tried it briefly on my X5.  It is pretty good, but also don’t feel much special.  I will try it on Harbeth later today and report back.  

Definitely let us know. Hope this thread keeps going amd includes more user experiences....Harbeths with SS and/or Tube. 


M40.2 Anniversaries?

Well, that’s certainly one impression of the current state of the art in loudspeaker design!

To be fair Alan Shaw has always stated that despite their seemingly low efficiency, Harbeth speakers do not present a difficult load to drive for any amplifier.


Yes, keep us posted on how you get on.

The McIntosh MC 275 seems like another solid choice with first rate build quality.

A little more power can never be a bad thing.
I watch that video, it is interesting.  But I have a question.  Is it really the speaker drawing power?  I don’t think the speakers draw power, but it is the amp pushing power, right?  
I have a question. if we play the same music, volume knob at the same level, to a more sensitive speaker, will it display that it is pushing the same 750W power?  Of course, the music will be louder pushing the same amount of power to a more sensitive speaker.

On the other hand, What if using an amp with smaller power playing the same song, how will that look like ...

I actually thought this would be more useful. But its semantics. 
@gte357s ,

’I don’t think the speakers draw power, but it is the amp pushing power, right?’

The speaker / amp relationship is pretty murky, at least to me, but the important thing to remember is that to get the same volume from the M40s a lesser powered amp might be forced into clipping, even if it’s for mere milliseconds.

Clipping happens when an amplifier runs out of power a bit like a car with a tiny engine going up a very steep hill. If there isn’t any protection built in to the amp, clipping can be disastrous for the loudspeaker.

With a more sensitive loudspeaker you certainly wouldn’t want to keep the volume knob in the same position unless you wanted to use it outdoors or in a much larger room.

This is assuming that it was capable of being played much louder in the first place. Not all more sensitive speakers are, but size is a good indicator.

It’s also worth remembering that loudspeakers are horribly inefficient devices. Hence the temperatures inside the voice coil can reach hundreds of degrees.

Much like car engines, most of the power going in is converted into heat. not sound (or in the case of the car engine, power). Overheating is a common enemy of both.

For those who like to play loud, thankfully before we are able to destroy our speakers by overheating, we should get a warning by experiencing a compression (and likely much distortion) in the sound.

It might simply not be worth going beyond a certain point of the amp volume dial as the speaker will tend to only get hotter, not louder.

I stream a Cambridge Edge NQ through balanced cables to a McIntosh 275 into Harbeth 7-ES3 speakers and I am extremely happy with the result, as I age, my hearing has deteriorated so I can't analyse the result except to say it is the best music I have enjoyed in 50 years of Hi Fi / audio experience
I run the Leben 600x w my Devore 0/93.  Very nice combination.  PM me if you want to discuss the amp further.

I watch that video, it is interesting.  But I have a question.  Is it really the speaker drawing power?  I don’t think the speakers draw power, but it is the amp pushing power, right?  
I have a question. if we play the same music, volume knob at the same level, to a more sensitive speaker, will it display that it is pushing the same 750W power? 
The amp makes the power and the speaker draws the power it can based on its impedance and the voltage that the amp makes. So for a given voltage, if the speaker draws one watt and its impedance is 8 ohms, into 4 ohms it will draw two watts if the amp is making the same voltage. Its a mathematical relationship.

Regarding the more sensitive speaker question, if the impedance is the same the power will be the same. Now the thing about more sensitive speakers is if the impedance is 8 ohms or more, the amp will not have to work as hard to make the same sound pressure level and usually will make less distortion. If it makes less distortion, it will sound smoother and more detailed (since distortion can mask low level detail). Now solid state amps in general tend to make higher ordered harmonic distortion compared to tubes, and so tend to sound bright, even though that distortion is fairly low. The reason we perceive it as bright is because the ear uses higher ordered harmonics to sense sound pressure and is thus keenly sensitive to their presence. It is this simple fact that is why tube amps are still around.

The reason solid state amps tend to sound bright is that usually they don't have *enough* feedback (some get around this by having none at all). Its pretty hard to design a circuit that allows for really high amounts of feedback (+35dB). So most simply don't. The result is that the application of the feedback itself, while suppressing some distortions, actually adds some of its own (which is almost entirely higher ordered harmonics; that which is not is IMD and both are very audible). Unless you can get over that 35-40dB range, this will be a problem, and its been a problem in solid state design since the inception of the transistor.

To get around this problem, many solid state amp manufacturers have resorted to a simple technique called 'lying'. But our ears don't lie- we've been hearing brightness and harshness in solid state amps for the last 60 years; that is why tubes and tube amps are still around decades on from being declared 'obsolete'.

My solution was to use a 300B Lampizator DAC to power a 500 watt Sanders SS amp =holographic tube magic with snappy transients and wide dynamics.
Read Allen Shaw's various essays on power requirements for the Harbeth 40 series. He advocates high power needs and presents demos to prove his point. I personally use Classe CAM 200 mono amps in conjunction with a Conrad Johnson tube preamp to drive my 40.1's and the sound is stupendous
go get an ARC VT100 mk3! works great on mine! My REF110 is not as good on the M40.1s. 
Go for  AIR TIGHT ATM-2.
KT 88 tubes
80 W per channel.