"This Harbeth User Group (HUG) is the Manufacturer's own managed forum dedicated to natural sound from microphone to ear, achievable by recognising and controlling the numerous confounding variables that exist along the audio chain. The Harbeth designer's objective is to make loudspeakers that contribute little of themselves to the music passing through them.

Identifying system components for their sonic neutrality should logically proceed from the interpretation and analysis of their technical, objective performance. Deviations from a flat frequency response at any point along the signal chain from microphone to ear is likely to give an audible sonic personality to the system at your ear; this includes the significant contribution of the listening room itself. To accurately reproduce the recorded sound as Harbeth speakers are designed to do, you would be best advised to select system components (sources, electronics, cables and so on) that do not color the sound before it reaches the speakers.

For example, the design of and interaction between the hifi amplifier and its speaker load can and will alter the sound balance of what you hear. This may or may not be what you wish to achieve, but any deviation from a flat response is a step away from a truly neutral system. HUG has extensively discussed amplifiers and the methods for seeking the most objectively neutral among a plethora of product choices.

HUG specialises in making complex technical matters simple to understand, getting at the repeatable facts in a post-truth environment where objectivity is increasingly ridiculed. With our heritage of natural sound and pragmatic design, HUG is not the best place to discuss non-Harbeth audio components selected, knowingly or not, to introduce a significantly personalised system sound. For that you should do your own research and above all, make the effort to visit an Authorised Dealer and listen to your music at your loudness on your loudspeakers through the various offerings there. There is really no on-line substitute for time invested in a dealer's showroom because 'tuning' your system to taste is such a highly personal matter. Our overall objective here is to empower readers to make the factually best procurement decisions in the interests of lifelike music at home.

Please consider carefully how much you should rely upon and be influenced by the subjective opinions of strangers. Their hearing acuity and taste will be different to yours, as will be their motives and budget, their listening distance, loudness and room treatment, not necessarily leading to appropriate equipment selection and listening satisfaction for you. Always keep in mind that without basic test equipment, subjective opinions will reign unchallenged. With test equipment, universal facts and truths are exposed.

If some of the science behind faithfully reproducing the sound intended by the composer, score, conductor and musicians over Harbeth speakers is your thing, this forum has been helping with that since 2006. If you just want to share your opinions and photos with others then the unrelated Harbeth Speakers Facebook page may be for you. Either way, welcome to the world of Harbeth!"

Feb. 2018
See more
See less

Tube Amp for Harbeth SHL5 - Minimum Power

  • Filter
  • Time
  • Show
Clear All
new posts

  • Tube Amp for Harbeth SHL5 - Minimum Power


    I'm thinking about using a tube amp for my SHL5. Now I ask myself, how much power does such a tube amp need, so that you can hear louder (no party volume) with the SHL5?

    Do you have any advices for me?

    Thank you in advance.

    Best regards

    LP12 - Klimax Kontrol/2 - Series 7 Mono - SHL5

  • #2
    See the manufacturer's advice regarding amplifier power here:

    Before you buy a tube type amp, also review the info in this thread:


    • #3

      I use a 45 watt amp with my SHL5. Works great!


      • #4
        Much depends on room size and listening habits, of course. However, more power is always better. For that reason alone I would advise against valve amplifiers. For the same money a solid state amplifier wil give you a lot more power. In addition it will have lower distortion and a much flatter frequency response under real life conditions, thanks to a lower output impedance and hence higher damping factor. Just watch here for a test of a 2x350 watt Yamaha pro audio amplifier that until recently sold for peanuts:


        • #5
          Hi Jo, a few years ago I changed from a older model Naim ( 32.5, HiCap, & 2 x NAP135 mono power amps). This is a quite powerful 90watt amplifier which had served me well for several years. Then I happened upon Jeff Day’s extensive review (Jeff’s Place) on the valve Leben RS28CX pre with Leben CS660 power amplifier using the same speakers I was using (Harbeth HL5 Super Plus) and his review touched on so much that was important to me regarding the reproduction of music. I made the change to this particular Leben and have never regretted my decision. Although the Leben is rated at only 40 Watts per channel compared to the Naims 90 Watts, the difference in power, volume, and in particular bass and dynamics is not an issue. Instead I gained a much more musical and rewarding sound which is less like a reproduction and much more like real people and real instruments playing music. Synergy is sadly under rated in the audio world and once you hear what the Harbeth HL5 speakers and Leben amplifier do together you will understand. Anyway search out Jeff Day’s review and see if it touches any bases with you too. Best of luck, Stuart


          • #6
            For me the design requirement for an amplifier is to be what Peter Walker once called a straight wire with gain. If we apply that to Leben amplifiers they are a quite desperate failure. For an example, see here: Their design guarantees a non flat frequency response, and even more so under the load of a real loudspeaker. So they alter the sound, and in unpredictable ways since every speaker has a different impedance curve and hence affects the amplifier's frequency response in different ways. Ideally, frequency response should be within 0.2 dB over the audible range. Any deviations larger than this will be audible. In additon, these Leben and many other valve amplifiers have pretty high harmonic distortion. Again, that is something that you may like, but it changes the sound of the music in ways not intended by the musician or the recording engineer. It is candle lit music rather than music in daylight. As an example of the vast superiority of even very cheap solid state amplifiers, see this test of the Yamaha AS500: (currently 300 euro for its AS 501 successor with digital inputs but otherwise identical).
            The second weakness of these Leben designs is their limited power output. Moving a lot of air takes a lot of power - a lot more than the power required to light a small light bulb. Some time ago Alan demonstrated the M40.1 in the Netherlands, and measured peak level power requirement proved to be over 500 watt per channel. I think even Alan was surprised. So what happens if you do not have that power? The result is that peaks in the music signal will be compressed (with clipping distortion as well). Of course, this will lift weak signal relative to the peak levels, giving you the illusion of detail resolution, but this is no more than the lack of the full dynamic range of the music (maximum of 96 dB on a CD and 16/44 streams, but much less on vinyl or FM radio). See here for a test of the sadly discontinued 2x350 watt Yamaha P3500S pro audio amplifier that until recently sold for about 500 euro, or even less: The test shows it is an impeccable piece of engineering of excellent build quality. I bought the 300 euro 2x250 watt P 2500S for my son, and not surprisingly the sound is perfect: a true straight wire with (a lot of) gain.
            A 370 euro 2x300 watt Crown XLS1502 Drivecore 2 may be a great modern class D amplifier. It looks fugly, but it has a remote on/off option, so you can put it somewhere out of sight. Add something like a 700 euro Pioneer U-05 DAC with variable balanced and unbalanced outputs and multiple digital inputs and you are all set for the modern age.


            • #7
              If only it were that simple!
              After 20 years in high end audio I am reasonably experienced in what the high powered, well measuring (and often) cheaper amplifiers offer.
              They mostly bleach the sound to some degree, losing natural tone and also not sounding like real music played by real people the way a carefully designed specialist design is capable of.
              A bit like trying to choose a bottle of wine by measuring the ingredients perhaps? or maybe choosing a speaker based solely on specifications.
              As Willem and I are clearly coming from totally different places can I suggest that you spend time auditioning several amplifiers (at home with YOUR system) and see if you find an amplifier that has a similar emotional synergy that my Leben amplifier has with my Harbeth Hl5 Super Plus speakers.
              Good luck in your search Jo!


              • #8
                Yes I do believe it is that simple, but then I am an academic researcher only too aware of expectation bias and steeped in the tradition of controlled double blind observation and cool measurement. Audio engineering is just science and has to be played by the rules of science. I am also someone who bought his first quality amplifier (a Quad 33/303) in 1971. I do listen too (to live and recorded music) and all I can say is that under controlled conditions there is no difference between good amplifiers used within their specifications. In fact, I once enjoyed the privilege of a private blind demonstration by Peter Walker of his three amplifier designs. At the time audiophiles were arguing that each generation sounded worse than the previous one. I thought I could indeed hear differences, but Peter Walker had an elegant pleasure in showing that I had not been better than random. Lesson learned. As it is, I own three generations of Quad power amplifers, all refurbished: a 303, a 405-2 and a 606-2. At lower levels they do indeed all sound exactly the same, but once I start playing at higher levels and into insensitive speakers, the more power the better, for better dynamics and a cleaner sound.
                Of course, everyone is free to like candle lit music by valve amplifiers (it is a free world). And of course, this does not preclude that you may have heard real differences, from a small amplifier being driven into clipping, a source driving the input stage into clipping, or a load dependent (usually valve) design altering the frequency response. The reassuring news is that all such things can also be measured: the resolution of a modern audio analyzer by the likes of AudioPrecison is many many times higher than that of the human ear (as humans we really do not have very good hearing).


                • #9
                  It's quite fine that srmusic is happy with his choice of amplifier, but it is not sensible to then claim that high power amplifiers somehow degrade music played through them, even though he may be convinced of this.
                  Many of the members here are not novices and have the listening experience to know how unwarranted such a claim is.