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HUG - here for all audio enthusiasts

Since its inception ten years ago, the Harbeth User Group's ambition has been to create a lasting knowledge archive. Knowledge is based on facts and observations. Knowledge is timeless. Knowledge is human independent and replicatable. However, we live in new world where thanks to social media, 'facts' have become flexible and personal. HUG operates in that real world.

HUG has two approaches to contributor's Posts. If you have, like us, a scientific mind and are curious about how the ear works, how it can lead us to make the right - and wrong - decisions, and about the technical ins and outs of audio equipment, how it's designed and what choices the designer makes, then the factual area of HUG is for you. The objective methods of comparing audio equipment under controlled conditions has been thoroughly examined here on HUG and elsewhere and can be easily understood and tried with negligible technical knowledge.

Alternatively, if you just like chatting about audio and subjectivity rules for you, then the Subjective Soundings sub-forum is you. If upon examination we think that Posts are better suited to one sub-forum than than the other, they will be redirected during Moderation, which is applied throughout the site.

Questions and Posts about, for example, 'does amplifier A sounds better than amplifier B' or 'which speaker stands or cables are best' are suitable for the Subjective Soundings area.

The Moderators' decision is final in all matters regarding what appears here. That said, very few Posts are rejected. HUG Moderation individually spell and layout checks Posts for clarity but due to the workload, Posts in the Subjective Soundings area, from Oct. 2016 will not be. We regret that but we are unable to accept Posts that present what we consider to be free advertising for products that Harbeth does not make.

That's it! Enjoy!

{Updated Nov. 2016A}
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Amplifier selection for your Harbeths (general, not specific Harbeth models)

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  • Are you afraid of your amplifier?!

    Originally posted by A.S.
    As I have said many times, "Harbeths will work well with all and every credible amplifier" ... Why shouldn't an amplifier work well with Harbeth? ... There must a a thousand different amps out there that will work really well with Harbeth.
    It occurs to me that what we've seen many times over the years is a deeply rooted fear of amplifiers - how they work, how their power is rated, different design concepts (Class A, AB etc.), tube or solid state, analogue of digital etc.. Let's try and demystify this once and for all. Of course, I am not an amplifier designer, and I readily admit that there will be detail issues which I don't appreciate but having said that here is my bold statement ....

    "You do not need to be afraid of your amplifier. Compared to even the simplest digital circuitry, an audio amplifier is conceptually a very simple device. All it has to do is to magnify the electron flow into its input terminals up into a bigger electron flow and deliver that to your speakers. You can think of an amplifier like the gears on a bicycle: gears magnify the energy you put in from your leg muscles into sufficient power to push the bike along the road. The amp does exactly the same.

    There are no mysteries at all in amplifier design. The concept of audio amplifiers dates back more than 80 years; the design principals are unchanged. Books have been written covering in the greatest detail the design of amps, and all the little tricks and techniques that can be applied to the circuit design. Aside from the op-amp, the QUAD current-dumper and the MOSFET output device, during the past 30 years there has been nothing fundamentally new in amplifier design - it's all been done before. How can you improve upon the motion of electrons through wires and components? You can't! The only advances we can expect now are in miniaturisation, design engineering (cost down), extra features (e.g. USB input), remote control and cosmetics etc. etc. - all peripheral issues."

    But - mentioned before - all electronics (slowly) age. No matter how sophisticated or elegant the design and manufacture of an amplifier its performance is only as good as the weakest component. Just like the bike: no matter how strong the gear cogs, if the chain has a weak link the full power will not be applied to the wheels.

    Q: In practice, what does this mean? We've covered this - it means that after, say, 15 years or so (I'm picking a number out of the air and assuming that good quality parts were used) the electrolytic capacitors in the amp will have degraded. If the designer anticipated this, and over-specified the capacitors to allow for the gradual reduction in capacity, it will extend the working life, but it will have increased the size and the cost of the amp. He may not have been able to do this. Miniaturisation of consumer electronics is a key design goal these days alongside shortened product life. These factors are inextricably linked. I urge the consumer to undertake some basic desk research to get a feel for the organisation behind the amplifier. Would you buy a new shiny car by only visiting the showroom? I wouldn't. I'd want to inspect the service bay, get a feel for the integrity of the service manager, talk to the mechanics. Why not approach hi-fi equipment the same way? Call the manufacturer. Talk to the service department. Ask them to explain what can go wrong, when and the costs involved. If they are open and up-front with you then invest in that product.

    Personally, I would never buy a used (second-hand) amp and expect it to perform as designed unless I could return it to the manufacturer for refurbishment. If I was given a used amp I wouldn't even bother to switch it on. I'd packed it and immediately despatch it to the manufacturer or his authorised agent providing that he could prove to my satisfaction that he had the skills, equipment and parts to service the amp as if he was the manufacturer. Just as with buying a car, one thing is for sure when you buy an amplifier: sooner or later you will need to know a man who can service it properly!

    So, in my opinion, the ability for the manufacturer to offer a lifetime aftercare (at a reasonable cost and with honesty so that he actually does replace defective components) is just about the most important criteria in selecting an amp. Far more important that hair-splitting arguments about whether X is better than Y. If X is better today, but Company X can't or won't give technical after care on amp X, then it's likely that at some point in the future due to ageing, Y will be better than X. That makes a nonsense of the whole hair-splitting thing.
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

    Comment


    • Re: Are you afraid of your amplifier?!

      An excellent post, Alan, that I very much agree with. If I may appear to be nit-picking, however, I don't quite agree with this part of your post:

      Originally posted by A.S.
      "You do not need to be afraid of your amplifier. Compared to even the simplest digital circuitry, an audio amplifier is conceptually a very simple device. All it has to do is to magnify the electron flow into its input terminals up into a bigger electron flow and deliver that to your speakers. You can think of an amplifier like the gears on a bicycle: gears magnify the energy you put in from your leg muscles into sufficient power to push the bike along the road. The amp does exactly the same.
      An amplifier doesn't actually magnify the electron flow. Not a single electron from the original signal will reach the speaker.

      In my view, what a power amp does is to condition and control the electron flow from the mains. The power arrives as an AC signal with a particular voltage and frequency. The first thing the amp must do is convert that energy into something which is suitable for driving a loudspeaker (that's what the power supply is for, it turns the energy into DC and normally drops the voltage to ca. 50V max). The second task of the amp is to modulate the energy from the mains into an exact copy of the input signal, only at a higher level (23 dB higher is the industry standard I believe).

      Your bike gears would be analogous to a transformer. No matter what transformers you choose, I doubt the output from the CD player of your choice would be sufficient to drive a speaker.

      Comment


      • Elevated temperatures and life expectancy ...

        You are absolutely correct of course.

        I find that in the interests of simplification it's often better to draw comparisons that are nearly if not comprehensively accurate. I find it easier to visualise the amp as a signal booster rather than a power gate. As you say, the literal function of the amplifier is to feed the amplifiers own mains-drawn power supply to the speakers in a highly controlled way - the control being that of the music waveform itself and the setting of the volume control.

        You do draw attention to the point that the design, construction and age related degradation of components in the power supply circuit of the (power) amp critically effects the overall performance. It is the part of the circuit working hard to make power available to the speakers (via the output devices) and we expect a lot from it. It has to have huge power reserves (acceleration potential) to follow the big musical events, but be silent enough so we can't hear hum and buzz during the quiet moments. The PSU components are under strain, and just like a car, to keep them in tip top condition requires periodic maintenance and component replacement. How often really depends upon ambient temperature, how hard it's worked, quality of original components, over/under engineering of the design, manufacturing cost constraints and good luck.

        I was discussing component life expectancy with a supplier last week. He showed me graphs which I'm told are typical of electronic, mechanical and fluid components. They show that for every 10 degrees C rise in ambient temperature the life expectancy of a component halves. As for 'life expectancy' it does not necessarily mean that the component totally fails (like a car windscreen wiper motor) but that it slowly degrades until it is well outside specification - such as a PSU's main reservoir capacitors. That electronic components age and slowly degrade is no surprise at all: this has been understood for decades by everyone involved in industrial or military equipment and of course, all component designers and manufacturers. It is the very reason why military-grade components are so hugely expensive - they are internally engineered and carefully seelcted to work at high temperatures for a very long time, but at a very price. Back in the real world of consumer hi-fi amplifiers assembled from affordable consumer-grade parts, it has to be expected that they won't last forever, hence periodic servicing is advisable before catastrophic amplifier failure - and destruction of your Harbeths.

        I must assume that better tube amplifier designers are experts in balancing their elevated operating temperatures and high voltages against component life expectancy. This is a subject I'd like to know more about.

        In my particular case, I declined the would-be suppliers invitation to use his component because I could not define precisely enough the stress it would be under, hence it's useful operating life. Some Harbeth users listen at low level to chamber music - others at high-ish levels to rock. We shouldn't gamble with shortening the working life of a Harbeth, which under careful conditions has already proved to be 30 years.
        Alan A. Shaw
        Designer, owner
        Harbeth Audio UK

        Comment


        • Leben CS300 - 12W, Harbeths sing

          I use a Leben cs300 integrated valve amp with my compact 7-es2. It's only 12 watts, not a big room. It's one fine amp and makes the Harbeths sing like never before.

          Comment


          • 12W - surprisingly loud

            Well that just proves the point. 12W is, in a moderately sized room, on music of moderate scale a surprising amount of power. If you recall the old QUAD tube amps they were only 15W/channel and they played very loud.

            Because the Harbeth electrical load is benign, little power is wasted.
            Alan A. Shaw
            Designer, owner
            Harbeth Audio UK

            Comment


            • 18W amp ....?

              How about 18W valve to drive M30?

              Comment


              • Amplifier power - what is your comfort zone?

                Well, to answer that please first refer to my former comments .... " ... 12W is, in a moderately sized room, on music of moderate scale a surprising amount of power ...."

                I constructed my answer carefully and used a number of critically important key words: I qualified the size of the room (moderate size), I qualified the type of music (music of moderate scale) and I used the word 'surprising' to describe my impression of power. An imperssion of power is not the same thing as real, scientific power! You can not beat physics - real power is real power! 12W is 12W. It can not behave as if it is 20W or 50W. It will only do the work of 12W. (Power = potential to do work). A 60W light bulb can not do the work of a 100W bulb. In the case of the amplifier, when we say 'work' we mean to push the bass unit's cone in and out. That is mechanical work.

                If you have this small combination of room size + small-scale musical tastes and listen at a low-level then a small amount of power is adequate. But if you change any of these qualifying conditions, then more power will be need. So, if the room is bigger and/or you listen further away and/or you like to listen louder and/or the music is more demanding (full orchestra needs more power than a string quartet) you will surely need more power.

                Think of this: if you want to illuminate a small room so that you can sit in the corner and read comfortably maybe you need only one 40W bulb hanging in the middle of the room. But if the room is bigger 40W is not bright enough: you need 100W bulb. Or, if you bring the light bulb nearer to your reading corner 25W may be sufficient. That's the same situation as listening close to or far away from your speakers: much of the light or sound is wasted and does not reach where you sit.

                Remember, power is just another word for energy-reserve. If you drive down the slow country lanes in your Rolls Royce maybe you are using 1% of the engines power reserve but you feel happy knowing that you have 99% power available to you. If you travel fast on the main road maybe you use 70% and you are reassured that you have 30% reserve. Or maybe you are a young driver in big hurry with a small car racing around the streets using 95% of the power with only 5% reserve but you are happy because your girlfriend has the impression of power when if fact it is 100% used up!

                What is your amplifier comfort-zone? Only you can decide how fast you want to travel, what power reserve you feel comfortable with and the cost.
                Alan A. Shaw
                Designer, owner
                Harbeth Audio UK

                Comment


                • I am using AVI laboratory series Integrated amplifier

                  and it sound great, very clean and precise, and very musical
                  I also have there CD player, which also sound great
                  my speakers are the 7es2
                  here is a link to there site

                  http://www.avihifi.co.uk/IntAmp/Integrated%20Amp.html

                  Comment


                  • Replacing my amp...

                    Dear all,

                    I am at the brink of replacing my amplifier (Bryston 3B-ST), and I need some advice on what to consider. My cd player is a Pioneer PD-65, and next on the chain is my lovely E.A.R. 834L valve pre-amp connected to the Bryston. My Harbeth Compact 7 mk I is the heart of the system, and all cablings are by Nordost.
                    I was thinking about obtaining a pair of second-hand Michell Alecto Monoblocs (but they're really hard to find). One of my friends said I ought to try the Naim power amp (he said the small one is decent enough). Another one said Sugden new class-A power was good also.
                    All advice and recommendations are warmly welcomed.

                    Cheers,

                    J.L.

                    Comment


                    • Re: Replacing my amp...

                      While it doesn't answer your question, I would like to suggest that before you make any amp purchase you audition a pair of the new Compact 7ES-3. I expect you will find an improvement far beyond what a change in electronics will provide.

                      Respectfully

                      Don Leman

                      Comment


                      • Re: Replacing my amp...

                        Dear Don,
                        I would certainly audition the new C7-3ES, but the thing is, we dont have authorized Harbeth dealer around here. I personally purchased my C7 directly from the UK.
                        I am sure there's a lot of improvement in sound quality in the mark III version. <sigh> Wish we had it here in Indonesia.
                        Anyway, thanks for your advice. Cheers.

                        J.L.

                        Comment


                        • Re: Replacing my amp...

                          J.L.

                          I know I'm a bit of a contrarian on the issue of electronics, but not having heard significant differences among the four amps (three s.s. and one tube) I've tried with my Harbeths (SHL5s and M40s), I'm wondering why you're looking to change from the Bryston. I know it only by reputation - excellent for quality and reliability. Is there an actual problem with it, or is it that you just want to try something different? If the latter, what is it you're hoping to achieve? Other than changing speakers, the next most significant sound change you could achieve would be (in my opinion) further work on room treatment, trying the speakers set up in MANY different locations, and/or actual room correction with a unit such as TacT, Lyngdorf, etc.

                          Ned

                          Comment


                          • Re: Replacing my amp...

                            Hi Ned,
                            There's absolutely nothing wrong with my Bryston. Infact the 3B-ST sounds natural, transparent, yet in a bit of laid-back region (perhaps, in my system the Bryston is matched with the valve EAR pre-amp?).
                            But, the REAL problem is that my Bryston has 110voltage, and I am living in a country where we use 220volt. Using a step-up transformer is an option. But I prefer replacing the power supply inside the Bryston. But again, the cost of changing the psu is almost as costly as purchasing a new small amplifier.
                            Maybe this explanation can clear up things why I wanna get a new amp for my Harbeth. =)
                            Any suggestions, Ned? Anyone? Hope anyone can gimme some solutions on auditioning a decent amp in my system. BIG thanks.
                            Cheers!

                            J.L.

                            Comment


                            • Harbeth in Indonesia

                              Good news for our Indonesian customers! There are Compact 7ES3s on their way this week to our excellent distributor there - Victory Audio. So now you can have a chance to hear them and then make a decision about amps.
                              Alan A. Shaw
                              Designer, owner
                              Harbeth Audio UK

                              Comment


                              • Re: Replacing my amp...

                                Hi J.L.,

                                That certainly answers my question on why you want - actually need - to get another amp. I couldn't recommend one over another; I think it largely depends on how much power you feel you need and how much you want to spend. I mostly use my Sunfire because I wanted to put the power issue completely to rest, and I like a cool running and absolutely quiet amp. (And - for me - the price was reasonable).

                                Ned

                                Comment

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