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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.

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

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  • Re: Speaker hum

    Originally posted by Hu
    Hi wlmdx,

    My Plinius SA 102 arrived, now I heard some hissing/buzzing noise from the tweeters and midwoofers, especially when I put in its class A mode, with A/B mode just very slight noise, nearly cannot hear. Now I just mailed dealer, have you ever contact to the dealer? Those noises are quite big. I did not hear merchanic hum from the amp itself, just from the speakers.
    Thanks!
    Hu

    Hi Hu,
    I contacted the US distributor and spoke to Mr.Scot Markwell. He advised me to try several things to rule out that I don't have a noisy amp. No matter how I tried the noise is still there. The only thing that changes the noise is the MUTE botton. If the unit on MUTE,I have the hiss/buzz. If the unit is on operation, the noise is lowered. Check the link:
    http://www.audioasylum.com/forums/am...ges/39053.html

    I have the similar problem. If your amp was produced in the 2004, you might fit into that category. He is currently waiting for a respond from Gary (Plinius factory) to see what's the fix. I am pressing for a new amp. Hope this help.

    Comment


    • Re: Speaker hum

      Originally posted by wlmdx
      Hi Hu,

      I have the similar problem. If your amp was produced in the 2004, you might fit into that category. He is currently waiting for a respond from Gary (Plinius factory) to see what's the fix. I am pressing for a new amp. Hope this help.
      Hi wlmdx,

      Thanks! My amp was produced now, in March. I hope the distributor will contact to Plinius to see what the problem is.

      Hu

      Comment


      • Re: Hiss, hum, buzz and standards of perfection in amps .....

        You're absolutely right Don. I did notice that Lao Hu mentioned a brand of speakers which, right or wrong, I associate with high efficiency and big drivers. This would definitely enhance the noise. If, for example, the other speakers were 6dB more sensitive than a typical Harbeth - say around 91/92dB - that would equate to a doubling of the spl of the noise just due to the speaker's higher efficiency. That definitely would be noticeable even on a casual listen.

        There is another factor here: the subjective quality of the noise. Is it hard and harsh with a definite tonal character to it? Soft like a gentle wind? Random and spluttering? Bass heavy? Top heavy? All these characteristics can give a clue to the precise noise source.

        I strongly believe that a gentle, warm, soft hiss can actually subjectively enhance music. Truly. It gives the ear a reference point around which to pivot the ear's Automatic Gain Control action. Strip away the noise so that the background is deathly quiet and the ear has to work much harder, constantly tightening and relaxing the muscles in the ear itself.

        I surely can't be the only person whose ears actually pop (and I can feel the muscles working) when I am listening to music such that I find myself swallowing to equalise the pressure. I guess that this ACG mechanism is an evolutionary protection mechanism: the protection from the damage of a loud sound and the 'gaining-up' of the ears sensitivity to a more useful dynamic range when that twig snaps some 20 feet behind - and life may hang on a thread.

        I have long considered that when pople talk of the so called 'hard' digital sound v. the 'soft' analogue sound they are actually commenting on the background hiss level. I dare to suggest that if noise, of a similar spectral character to that associated with analogue recording, was deliberately superimposed onto even the 'hardest' digital recording that it would sound perfectly acceptable.
        Alan A. Shaw
        Designer, owner
        Harbeth Audio UK

        Comment


        • Re: Hiss, hum, buzz and standards of perfection in amps .....

          Originally posted by A.S.
          You're absolutely right Don. I did notice that Lao Hu mentioned a brand of speakers which, right or wrong, I associate with high efficiency and big drivers. This would definitely enhance the noise. If, for example, the other speakers were 6dB more sensitive than a typical Harbeth - say, around 91/92dB, that would equate to a doubling of the spl of the noise just due to the speaker's higher efficiency. That definitely would be noticeable even on a casual listen.
          I do not know what sensitivity West Lake have, but I got surprised at the store that noise is much more obvious (I stood about 1M far from the speakers and could hear quite big noise, with my M30 I have to be closer to the speakers. I asked the dealer what the speakers they are broadcasting, they say they are West Lake.

          Hu

          Comment


          • Re: Hiss, hum, buzz and standards of perfection in amps .....

            Speakers made in USA? Then I think that the efficiency will be much higher than Harbeth. That is the reason that you heard the hiss more distinctly. Plus, of course, the fact that the Harbeth have a flat frequency response.
            Alan A. Shaw
            Designer, owner
            Harbeth Audio UK

            Comment


            • Re: Amplifier selection for your Harbeths (general, not specific Harbeth models)

              The recommendation of powering all components from a single wall socket is interesting and not something I have heard before. Two things come to mind:

              Could this be different in England than it is in the US?

              Power has become a very big deal with American audiophiles (maybe the rest of the world too). Expensive power cords, power conditioners, and so forth. We don't need to have that conversation, but I want to remark on a couple of things. First, common practice has been tending toward dedicated circuits for one's audio system, and usually more than one such circuit so that you isolate source components from amplifiers, analog from digital, etc, etc. It's all connected back at the breaker box, but nevertheless, this is what people do. I am not aware of this creating ground loop problems for people.

              Another practice is to avoid power strips and the like and, if not using a conditioner, plug everything straight into the wall. To do that and to implement your suggestion would require either very few components or a lot of outlets at the one circuit drop. Both are possible.

              Comment


              • Re: Hiss, hum, buzz and standards of perfection in amps .....

                Originally posted by A.S.
                Speakers made in USA? Then I think that the efficiency will be much higher than Harbeth. That is the reason that you heard the hiss more distinctly. Plus, of course, the fact that the Harbeth have a flat frequency response.
                In the case, how could such amps drive USA speakers? I could hear from those speakers very distinctly, not only hiss from tweeters but very annoying hum (somehow like the noise of PC fan) from midrange in its A class mode.

                And, if that nearly only makes such hiss/hum when it is in A class mode, in A/B mode you almost cannot hear, does that have something to do with the mains?

                Hu

                Comment


                • Mains ground points at home and in the studio

                  I'm sorry to say that I can claim no originality for the observation that all grounded hi-fi equipment should be connected to the supply at one point in the room. I should have adhered to this - it is basic electrical engineering and applies the universe over. But convenience and haste made me overlook this.

                  If the equipment is not grounded i.e. has a two-pin mains plug not three, then the is no issue with ground loops by definition and you can (probably) plug-in to the supply anywhere in your house or your neighbours.

                  Taking the supply back to the mains inlet board especially in old houses with strange wiring has to be a good idea, but it's a rather extreme option.

                  I really should have recalled the problems I had eliminating hum from recordings made off my (grounded) amplifier onto the sound card in my (grounded) PC. The PC was in one corner of the same room adjacent to a convenient wall socket ; the amp in the opposite corner adjacent to another socket and I ran a phono to jack screened (hence grounded both ends) lead between them. Eventually, three safe solutions were found to work in breaking the ground loop: an optical connection (no connection to ground at all), high quality 1:1 audio signal isolating transformers (expensive, some small audio quality issues - this has been the standard practice in the BBC for some 70 years) or powering the PC from a mains isolating transformer of the type used on a building site. In avery case, the trick is to prevent a ground loop. (Thought: there is a fourth option: to power the PC from a long mains cable plugged into the amp's mains socket but that was ugly.)

                  Finally, powering from extension leads plugged into one mains wall socket: fine; no problem - this is what I do. You can run several of these off one socket, sufficient to power everything but make sure they come from one single or double wall socket and that you don't exceed their rating.

                  I was discussing studio grounding during an installation of M40 Actives at BBC TV Centre a few weeks ago and the wireman confirmed that the studio had a good, solid 'star' earth point in an equipment rack. All audio signals were of course balanced (hot, cold and ground or live, return and ground) and that although they were distributed around the studio with balanced shielded cable the shields were snipped off at the distant end as one end was bonded together at the star earth point, which was connected to the building's earth strap to ground. Hence, no possibility for ground loops since there is no cable between signal grounds: they are all at the same potential, at the same point in space in the equipment rack.
                  Alan A. Shaw
                  Designer, owner
                  Harbeth Audio UK

                  Comment


                  • Re: Amplifier selection for your Harbeths (general, not specific Harbeth models)

                    I believe that mains power in the US is not balanced as it is in the UK. Hence a market for power conditioners that deliver balanced power (Equi=tech, Balanced Power Technologies). People who use these say they never have ground loop problems.

                    Comment


                    • Mains live and neutral. Not interchangeable!

                      Originally posted by danrubin
                      I believe that mains power in the US is not balanced as it is in the UK...
                      Sadly, completely untrue. The situation in the UK - and I would guess the world over - is that the 'neutral' feed is connected to a huge, solid stake buried in the ground at the power station. In your home your 'earth' pin is also connected (or definitely should be connected) to a solid stake driven ito the ground by or in your home with a thick cable: go and look for it: have it routinely checked: know where it is. There is no way at all that this power transmission system can be described as 'balanced'. It is exactly the opposite: it is unbalanced, single-ended from the power supply just as a phono-phono lead is.

                      So, the 'live' feed is swinging + then - volts relative to the neutral wire 50 times a second (or 60 times a second in the USA etc.) and the neutral wire is at or very close to the same potential as the earth wire.

                      IT REALLY MATTERS that you know which pin is truly 'live' and which pin is truly 'neutral' on each and every mains socket in your house. In the UK we have a really solid plug (also in Hong Kong and other empire-legacy places) where this can not be confused: the plug can only be inserted one way. But elsewhere, you can often plug in a two-pin (non-earthed) plug either way round and accidentally swap over the neutral and live.

                      WHY DOES THIS MATTER?
                      Because a shock from the true neutral is not likely to kill you. It is so close to ground potential that it can (almost, but not actually) be considered 'ground'. But if you get a shock from the true 'live' it could/will kill you.

                      HOW COULD THIS HAPPEN?
                      If your equipment uses a mains switch or a standby circuit that only switches one side of the mains supply - it would be designed to expect to switch the live side. The other side of the supply will flow around the circuit and to the wall socket even when the switch is open and internally the entire equipment will be charged. That's OK if the switch has interrupted the true live feed, because the neutral - almost at ground potential - willl be running around the circuit. But if you inadvertently transpose the live and neutral, then the switch is not protecting you: the entire circuit is live even when the switch is off, and in the case of electrical failure, the case could become live. If there was no proper safetly ground connection then when you touch the case the mains live passes through your body seeking the ground. Fatal.

                      http://www.cherwell.oxon.sch.uk/prm/efact10.htm

                      http://www.theanswerbank.co.uk/How_i...tion40795.html

                      http://www.zen22142.zen.co.uk/Circuits/Power/tps.htm

                      Conclusion: Check your home wiring for the safetly of your entire family. Be 100% sure it is wired correctly. Know which pin is truly the live pin in each and every socket right through the house (you can buy a simple neon tested for this). Make sure the earth bonding is perfect. Never ignore the earth pin if the equipment expects a saftely earth. Get your wiring checked periodically: unbeknown to you, earth wires do loosen and drop off; one day your life may depend upon its integrity.

                      PS. Did you know that over a period of many years the 50/60Hz mains cycling causes the screws in plugs and sockets that crimp the wires to actually unscrew? Make sure all connections are tight.
                      Alan A. Shaw
                      Designer, owner
                      Harbeth Audio UK

                      Comment


                      • Re: Mains live and neutral. Not interchangeable!

                        Originally posted by A.S.
                        Sadly, completely untrue.
                        Ah, so it's untrue that power is balanced in UK. Here is a description of the balanced power devices I referred to, which I am borrowing from someone's Internet post:

                        Balanced power (best for front end stuff not necessary for amps) splits the AC potential in two. Instead of 120V between the the hot blade (of the plug) and the (nominally zero) neutral blade (plus your ground of course) it splits it so that there is +60 V from one blade to ground, and -60V from the other blade to ground. You still get 120V between the two plug blades, but the blades are always opposite polarity relative to ground. So any noise carried in the line (mostly hum but also RFI) is self-cancelling. Studios have used balanced power for years, but it was only UL approved for consumer use about 8 years ago.

                        Comment


                        • Balanced mains and conditioners.

                          Originally posted by danrubin
                          ... it splits it so that there is +60 V from one blade to ground, and -60V from the other blade to ground. You still get 120V between the two plug blades, but the blades are always opposite polarity relative to ground. So any noise carried in the line (mostly hum but also RFI) is self-cancelling. ...
                          This sounds perfectly plausible - in the UK/Europe the voltage would not be 120V but 230V, which is why an electric shock in Europe is often fatal.

                          However - and I'm on the very edge of my knowledge here - the system described above could only balance-out the hum and RFI (if there is any) between the power conditioner and the hifi equipment. Since that is only a few feet of cable compared to the perhaps hundreds of miles of cable back to the power station don't the undoubted theoretical benefits seem a trifle diminished by distances involved?
                          Alan A. Shaw
                          Designer, owner
                          Harbeth Audio UK

                          Comment


                          • Re: USA voltage stability for amps etc.

                            Something strange has happened here ..... Kevint I seem to have overwritten your message. Sorry. The point you made was that uSA 120V being half the UK voltage would draw half the current.

                            If you would like to resubmit your message I will try and work it into my answer. Sorry again.
                            Alan A. Shaw
                            Designer, owner
                            Harbeth Audio UK

                            Comment


                            • Re: Amplifier selection for your Harbeths (general, not specific Harbeth models)

                              My original message was saying power stablity is more an issue in 110V countries. I experienced flashing light whenever the motor of dryer or air conditioner start running there. And I don't experience this problem in my home country where is 220V. So I guess 110V country has more power stablity concern than we have in 220V country, at least here in Hong Kong.

                              Comment


                              • Re: Amplifier selection for your Harbeths (general, not specific Harbeth models)

                                Hallo,
                                have you ever tried Naim Nait 5i with Monitor 30?
                                thank you,

                                David

                                Comment

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