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"This Harbeth User Group (HUG) is the Manufacturer's own managed forum dedicated to natural sound, realisable by controlling the confounding variables between tthe microphone and the listeners' ears.

For example, the design of and interaction between the hifi amplifier and its speaker load can and potentially will alter the sound balance of what you hear. To reproduce the sounds captured by the recording microphones, as Harbeth speakers are designed to do, you would naturally select system components (sources, electronics, cables and so on) that do not color the sound before it reaches the speakers.

Identifying components for their system neutrality should, logically, start with the interpretation and analysis of their technical, objective performance, as any and every deviation from a measurably flat frequency response at any point along the serial chain from microphone to ear is very likely to cause the total system to have an audible sonic personality. That includes the contribution of the listening room itself.

HUG specialises in making complex technical matters simple to understand, aiding the identification of audio components likely to maintain a faithful relationship between the recorded sound and the sound you hear. With our heritage of natural sound, HUG cannot be really be expected to guide in the selection, approval, endorsement or even discussion of equipment that is intend to introduce a significantly personalised sound to the audio signal chain. 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 electronics offered there. There is no on-line substitute for that time investment in a dealer's showroom.

If you desire to intentionally tune your system sound to your personal taste, please consider carefully how much you should rely upon 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, listening loudness and listening room treatment, not necessarily leading to appropriate equipment selection and listening satisfaction for you.

Alternatively, if faithfully reproducing the sound intended by the composer, score, conductor and musicians over your speakers is your audio dream, then understanding something of the issues likely to fulfill that objective is what this forum has been helping with since 2006. Welcome!"


Jan. 2018
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Woofer driver positioning on baffle - in front or behind baffle?

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  • #16
    Lags in crossovers?

    Originally posted by A.S. View Post
    The velocity of sound waves coming from the bass/mid and tweeter are the same regardless of frequency.
    Yes, so if I were to assume that an ideal crossover had managed to exactly time align tweeter and bass/mid and then the bass/mid was moved back by 20mm would that mean that sound from the bass/mid now lagged behind the sound from the tweeter by the fraction I suggested?

    I am confused as to whether you're point is that the statement is incorrect or that it is simply not the right way to view this issue.

    Originally posted by A.S. View Post
    That is, approx. 340mS (very, very, very slow compared with the velocity of light).

    At 340Hz, the wavelength of each cycle of a sine wave is 1.0m. At 3400Hz (3.4kHz) the wavelength is 0.1m (10cm) .....
    340 Hz is around F above middle C isn't it; 2cm as a fraction of 100cm (the wavelength) now seems relatively large (1/50th). 3400 Hz is close to the top of the piano range; 2cm as a fraction of a 10cm wavelength is significant (but my assumption is that the bass/mid isn't doing anything at this frequency.)

    The relationship between wavelength and frequency (wavelength = velocity/frequency) is one that I had long since forgotten, thanks for the reminder.

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    • #17
      Time (mis) alignment

      Originally posted by weaver View Post
      Yes, so if I were to assume that an ideal crossover had managed to exactly time align tweeter and bass/mid and then the bass/mid was moved back by 20mm would that mean that sound from the bass/mid now lagged behind the sound from the tweeter by the fraction I suggested?
      Let's be honest, we're not really "time-aligning" the two drive units. We can't do that in a passive crossover. We could (theoretically) do that in a digital crossover because we'd hold the data that would otherwise feed the tweeter directly in a frame-buffer and release it at exactly the right time. But analogue passive crossovers don't have frame stores do they. So we have to say "time alignment" in quotes because that's impossible to achieve without digital technology, when, should you wish, it would be a trivial matter to delay the signal to the tweeter by a second, a day, a week .... just depending upon how big the frame store is. But "time aligmnent" of a compromised type is definitely what we are aiming at.

      340 Hz is around F above middle C isn't it; 2cm as a fraction of 100cm (the wavelength) now seems relatively large (1/50th). 3400 Hz is close to the top of the piano range; 2cm as a fraction of a 10cm wavelength is significant (but my assumption is that the bass/mid isn't doing anything at this frequency.)
      Right to say that 2cms as a fraction of 10cms is a huge percentage. Percentage of what? Percentage of the cycle. And we know that a cycle is another way of saying 360 degrees ......

      And most definitely, the bass/midrange is working nearly at full loudness to about 3kHz, is at about 1/3 loudness to 4kHz, tenth loudness to perhaps 6kHz. Again, crossover filters gradually fade out the woofer and fade up the tweeter. IT IS THIS LARGE OVERLAP BETWEEN DRIVE UNITS WHERE THE "TIME ALIGMENT PROBLEM" LIES. If the bass/mid's contribution stopped dead and handed over sharply to the tweeter the problem of mis-alignment would be inaudible.

      We've covered crossover slopes in this TechTalk issue.
      Alan A. Shaw
      Designer, owner
      Harbeth Audio UK

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      • #18
        Consequences of signals out of phase?

        Many thanks Alan, that starts to become much clearer.

        Back up at the top of the thread you said:

        It's about path length adjustment.
        which appears to be the better way of thinking about it; as you say above, actual "time alignment" would be something else.

        Is the (possible) reduction in energy in the crossover region due to "time alignment" issues therefore a consequence of signals being slightly out of phase and cancelling each other?

        To come back to your query about the technical level at which you pitch the TT videos. In general I think you do very well at keeping things in 'everyday' language. In common with most industries though there are terms which can appear to mean one thing if taken literally but their accepted usage within that industry actually means something else -"time alignment" being the example here.

        That said, I believe your explanations are clearest when you describe things directly and don't try to over-simplify, perhaps it is just a case of making clear when a term being used isn't being used literally.

        Lastly, a point which crops up frequently is the difficulties audiophiles can get into when we believe we understand something, when we believe we know that such and such component is making such and such contribution - when in fact the science says something completely different. But if we don't understand the science, if the terminology doesn't actually mean what we think it means, it's easy to see how these issues are perpetuated.

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        • #19
          Time alignment of recording microphones

          Just crossing over with the comments from Paul G Smith in the mic thread regarding spot mics and so on got me wondering about delays in sound reaching us - or more specifically microphones - in an orchestral context.

          A thread on recording.org answers much of what I had been thinking about.

          It also talks about 'time alignment' in the way that I had originally assumed was meant in this thread.

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