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"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 http://bit.ly/2FEgoAy may be for you. Either way, welcome to the world of Harbeth!"


Feb. 2018
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Some real tweeters - baby great tit chicks in my garden

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  • Some real tweeters - baby great tit chicks in my garden

    I'm rather keen on garden birds and have been keeping an eye on this years brood in one of my bird boxes, which I spruced-up for the season. I think I caught the baby chicks a day or two before they fled; the first brood unexpectedly died for no apparent reason and I dare not investigate why the nest is now silent for another few days. One parent bird was seen this morning going in, without food. Some super photos here. More on great tits here. Pecking milk bottle tops here.

    Anyway, placing a microphone close to the entrance hole, I recorded these sounds of perhaps three or four blue tit chicks. Anticipating a wide frequency response from these real tweeters, I recorded at 96kHz sampling, 24 bit (max. recordable frequency 48kHz). Can you guess what the highest frequency is these chicks generate? Can you also guess what the dominant frequency is and the relevance for loudspeaker design?



    NOTE! It is not possible to capture the frequency range of these tweets in an MP3 file.

    'Bird brained'? Think again, here.
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

  • #2
    Spectral analysis of the above recording

    I'll answer my own question.

    The dominant frequency in those tweets is about 7kHz. That's an octave or so above crossover frequency in a typical hi-fi speaker speaker. An excess of energy in that region is extremely fatiguing to the human ear and the implications for loudspeaker design are obvious.

    I've made a screen-cam of the above audio track being played through a spectral analyser. Due to a limitation of the screencast recording codec, there are spurious additional tones in this video, not present in the source recording above. The screen image is of the original source file. What conclusions can you draw about harmonics and of the highest pitch generated by these baby birds? If you expand to full screen, you can read the horizontal frequency scale more easily.



    Discussing audio amplifiers (irrelevant) and speaker stands (irrelevant) is just so much more fascinating than being curious about, and learning from, the sounds around us, don't you think?
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

    Comment


    • #3
      Too wide a bandwidth?

      Originally posted by A.S. View Post
      I'll answer my own question.

      The dominant frequency in those tweets is about 7kHz. ... What conclusions can you draw about harmonics and of the highest pitch generated by these baby birds?
      Question: is the "dominant" frequency the same as the fundamental frequency? I assume it is but just checking.

      I suppose that if 7kHz is the fundamental, I'm not going to hear anything above the second harmonic, and no human is going to hear anything above the third. I also imagine that the highest pitch is several multiples of 7kHz, so really really high.

      Does this have any real world implications for audio or speaker design? Maybe it suggests that super high-def sampling is actually undesirable, because you will have your amplification at least attempting to reproduce those ultrasonics, for no useful purpose?

      Comment


      • #4
        Audio formats and supersonic HF energy

        Originally posted by EricW View Post
        ...Maybe it suggests that super high-def sampling is actually undesirable, because you will have your amplification at least attempting to reproduce those ultrasonics, for no useful purpose?
        If you examine the official ("Scarlet Book") specification for SACD, you will see that it demands the presence of a low pass filter at around 50kHz. This is because the DSD process entails an awful lot of ultrasonic noise – it is an extreme version of the noise shaping technique extensively used in digital audio – which, the DSD developers felt, was a risk if it was allowed to pass through the audio chain and, ultimately, to the speakers.

        Another factor that concerns me, for which I have been able to find little evidence*, is the possible damaging effect of ultrasonic energy on human hearing. We all know that excessive amounts of energy within the audible region are bad for you and there exists legislation to time-limit the exposure we are 'forced' to endure in the course of employment, the limits being dependent on the sound pressure level. But because sound energy is largely inaudible above, say, 15kHz (at normal levels), this does not imply that such energy is harmless to the auditory system.

        Please don't get me wrong here – I'm not suggesting that the ultrasonic energy levels encountered in high resolution digital music are in any way harmful to man or machine but I am enormously skeptical as to the value of any content well into the ultrasonic region. But, with reference to the DSD problem mentioned above, I have a concern: The Scarlet Book demanded a filter on the analogue outputs of licensed SACD players. It also denied those players any digital output better than 16/48 PCM, so the level of 'exposure' to the massive amounts of ultrasonic noise was limited.

        DSD now appears to be undergoing something of a resurgence through the availability of DSD files as a downloadable format; a format largely free of the Scarlet Book 'rules' that governed the licensing of SACD players, which in turn means that fallout from the noise shaping (which remains an essential part of DSD processing) is likely to find its way into tweeters and our ears.

        Perhaps Alan ought to stock up on spare tweeters!

        * Although I'm sure I'm either not looking hard enough or looking in the wrong places.

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