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Loudspeaker listening - what I hear

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  • #16
    Spacer around instruments

    It was the space around the trumpet that put it at a distance - my very first reaction was of an off-stage sound from a lofty point*, but the relative loudness seemed to contradict that. It would probably be more accurate to say that I thought the trumpet was in an open indoor space - one which allowed the notes to build and hang around in the air - which I guess means that the reflections were suitably separate from the direct sound; had it been distant but close to hard surfaces then the sound would have been different.

    Conversely the piano sounds as if it is being played rather softly - at the very beginning I thought it could in fact be a fortepiano. I don't know enough about listening critically to this type of thing to say whether, by playing the piano softly it would excite less reverberation or not, but the space around it seems different to the trumpet; to have less openness, less brilliance. At the same time it doesn't (to me) sound up-close in a reach-out-and-touch-it way as A.S. said

    I like the intimacy of the piano
    but though I don't actually disagree, I also don't find that there is a particularly tangible 'closeness' to the sound - that may just be down to a definition of terms though.

    There do seem to be two different aspects going on though:

    The size of the space and the distance from the audience

    *you get them in eg the Verdi Requiem, I heard it in an amateur performance at, I think, Ealing Town Hall where it was up on the balcony.

    Comment


    • #17
      The trumpet and the piano's balloon of sound

      Originally posted by weaver View Post
      It was the space around the trumpet that put it at a distance ... Conversely the piano sounds as if it is being played rather softly ... by playing the piano softly it would excite less reverberation ... but the space around it seems different to the trumpet; to have less openness, less brilliance. At the same time it doesn't (to me) sound up-close in a reach-out-and-touch-it way as A.S. said...
      Several points here. First, regarding the relative loudness. It's important to appreciate that the way the trumpet shoots sound out into the hall compared with way the piano projects itself is completely different. In fact, it's possible (even probable) that the piano is capable of generating a much higher loudness, but that balloon of sound will radiate (roughly) in 360 degrees around the instrument (assume lid closed). The trumpet bunches up all its energy into an intense beam of sound, exactly as brass instruments were invented to do. So, I don't think the relative loudness of these two instruments can reliably tell you much*. What is much more revealing (to me) is the amount of reverb around them. That's the real tell-tale about their relative positions.

      Your comments about the piano surprise me a little. The acoustic space around the piano is totally different to that around the trumpet. As noted above, the piano is widely spread left-to-right where as the trumpet is quite clearly a point source placed at a specific point across the sound stage. There is no reverb or air around the piano plus it spreads across the entire L-R sound stage. Surly that can only mean one thing .... we must be standing right next to it, with the full width of strings running (approximately) left to right.

      Are you with me on this point?

      * and nothing at all if the trumpet is independently mic'd from the piano.
      Alan A. Shaw
      Designer, owner
      Harbeth Audio UK

      Comment


      • #18
        Is it just me?

        Just a quick note on Listening to echoes -1. I feel that I am seated more than 50 to 100 feet way. I am unable to listen more because it hangs half way with IE9, Firefox10, Chrome, Opera (Window7).

        About listening to echoes-3, I agree with Weaver except the part about the distance of trumpet and piano. On the first instance, I thought the trumpet was closer than the piano but than the suggestive words of Mod and Weaver makes me to think the piano is closer but I just don't know.

        It is obvious that I listen differently from Alan or Weaver because the moment I heard listening to echoes-3, my mind is fixed around the trumpet sound as the primary instrument and piano was secondary to it and received less attention from myself. I am unable to judge the distance nor I would have paid any attention to it. Strangely, I am very good with vocals that I can judge number of singers and distance but not so much with instruments. It looks like I accept colouration (reverberation) as part of a note though I understand reverberation is important for human survival to judge location and distance but somehow I am on a different wavelength here

        ST

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        • #19
          Originally posted by A.S. View Post
          Are you with me on this point?
          Yes, absolutely.

          In live performance though, both the trumpet player and the pianist would be aware of this and tailor their performances accordingly wouldn't they.

          If a supplementary question is allowed at this point: in a concert hall is the beam of sound vs the 360 degree sound significant in relation to reverb? eg would the piano sound have more early reflection points than the trumpet?

          Comment


          • #20
            Omnidirectionality and echoes

            Originally posted by weaver View Post
            If a supplementary question is allowed at this point: in a concert hall is the beam of sound vs the 360 degree sound significant in relation to reverb? eg would the piano sound have more early reflection points than the trumpet?
            Good question. First, I picked this piano + trumpet piece with care to highlight just these sort of issues. Yes, in theory and sound source that radiated omidirectionally in a confined space (a hall) would presumably generate plenty of early reflections from obstacles in close proximity to it. If we are talking about a piano, that would include the stage floor around the piano, then the musicians and their stands and instruments near the piano. But we know that early reflections, by definition are from solid surfaces quite near to the source (the piano) and that their sound wave doesn't have much further to travel to our ear than the direct sound. So those early reflection would all fuse together in our brain and be completely inseparable from the direct piano sound. So it is not going to be possible for a listener to gauge the size of the hall from listening to the piano with its early reflections if either we are physically sitting next to the piano or the piano's microphones have, in effect, put us there.

            The trumpet, conversely, has no (or let's assume that) early reflections. It sends out its beam of sound like a searchlight, and in the same way that a squash ball exits the point of impact with a wall at the same angle, the reflected trumpet sound beam will make its way to the microphone and arrive slightly after the direct sound. Eureka! If we subconsciously time the difference between the high-intensity direct sound beam and the reflection, we know how far away the walls are, and hence how big the space is. We can't gather any of that spatial awareness information in this recording from the piano. That's because it, unlike the trumpet, is 'dry', with little or no late reflections that would give us the clues we need to estimate the size of the recording venue. So then, the most impulsive instrument (the trumpet) has unambiguously revealed the size of the hall. On the Bolero clip I highlighted the drum as exciting the room echo - once again, a high energy impulsive blast of sound has produced a nice, clean, identifiable late reflection.

            What next? Well, let's forget about level differences between the trumpet and the piano. By using multi-microphones those become irrelevant, and we could easily make the piano louder than the trumpet in the mix-down if we wanted to. The real issue I want to get to is that the trumpet has some 'air' around it (i.e. generates echoes) whereas the piano is completely dry and super-wide. What must that mean?
            Alan A. Shaw
            Designer, owner
            Harbeth Audio UK

            Comment


            • #21
              Does this have to do with mic placement?

              The piano appears to have no late reflections in its recorded sound, so either:

              - there weren't any to record or the microphones were of such a type or in such a position so as not to record them.

              The trumpet does have late reflections in its recorded sound so:

              - the microphones were of such a type or in such a position so as to pick them up.

              Based on what I have learned here about microphones I would therefore suggest that:

              - the piano mics were closer to the instrument and/or more directional

              - the trumpet mics were further from the instrument and/or more omni-directional.

              Comment


              • #22
                Perfect answer. So knowing what you now know, what do you think is the most probable arrangement of microphones at the recording venue?
                Alan A. Shaw
                Designer, owner
                Harbeth Audio UK

                Comment


                • #23
                  I have been proceeding on the basis that piano and trumpet had separate mics; this is because I assumed that if a single pair of mics were close to the piano that the direct piano sound would swamp the trumpet's reverb - but that is only a guess.

                  To keep it as simple as possible though, could we place a single omni-directional stereo pair in the equivalent of row 1 with the piano directly in front of it. The trumpet placed the other side of the piano from the mics and that bit further away. The pianist most likely having their back to us and facing the trumpet player.

                  This would I think, explain the 'wide' piano sound with the lack of reverb. The direct sound from the trumpet is perfectly able to cut through the piano and it's 'late' reverb is picked up by the 'back' of the mics?

                  Comment


                  • #24
                    Using revcerberation to create a deep listening acoustic space at home ...

                    Originally posted by weaver View Post
                    I have been proceeding on the basis that piano and trumpet had separate mics; this is because I assumed that if a single pair of mics were close to the piano that the direct piano sound would swamp the trumpet's reverb...
                    We can't go much further with deconstructing what we heard, because we can't even be sure that the trumpet and piano were recorded at the same time or even in the same hall. For all we know, the piano could have been recorded in a studio, the trumpeter in a hall listening to the piano on headphones and playing along with it. Or maybe both are in separate dry studios and the reverb is electronically synthesised onto the trumpet. What we can say I think with high confidence is that the piano is rather closely mic'd. There is barely any reverb 'air' around it.

                    Let's compare that trumpet and piano with a private recording I made at the Fairfield Hall, Croydon, audience of two (Peter Katin and myself). So without any damping from the audience to soak up the reverberation we can clearly hear the hall. As I recall, my two B&K omni mics were spaced about 1m apart, the Steinway piano lid was open and facing the mics, and the the mics were about 2.5m away from the lid. It strikes me that in contrast with the piano on the Grieg recording, there is much more of a sense of acoustic space on my recording, and this implies to me that the mics on the Grieg must have been somewhat closer to the piano and/or they were more directional, contrary to your theory. And that belief is reinforced by the very wide piano image width (check it on headphones) which from experience I associate with getting the microphones in close to the long strings. The third clip is from later in the Grieg piece, piano only. Perhaps the microphones are only 1m away from the piano - a small difference given the size of the hall - but one that has changed our perspective compared with my recording.

                    Grieg piano + trumpet again

                    My recording of Steinway piano at the Fairfield Hall (no audience)

                    Grieg piano, later excerpt sans trumpet

                    So now we are at the point I hope that by careful listening to any given recording we can use the reverberation or 'air' around individual performers to tell us a lot about the size of the hall and the recording technique. Even if the recording is made up of layered performers patched together from different takes in different halls, we should be able to find tell-tale clues in the mismatched air around individual musicians. Depth, or Z plane information is really important to audiophiles because the more accurate, credible depth information there is, the more involving the listening experience. And that brings me full circle to a point about how judging this recorded 'air' very much depends upon the loudspeaker technology ....

                    (More later)
                    Alan A. Shaw
                    Designer, owner
                    Harbeth Audio UK

                    Comment


                    • #25
                      Recording the piano

                      Thanks for the extra recording Alan.

                      Quick question: how close does the mic have to be to a piano before it starts to pick up the sounds of the mechanism itself (the mechanical bits) - does it actually have to be under the lid for example?

                      Comment


                      • #26
                        Miking the piano

                        Originally posted by weaver View Post
                        ... how close does the mic have to be to a piano before it starts to pick up the sounds of the mechanism itself (the mechanical bits) - does it actually have to be under the lid for example?
                        Isn't the internet wonderful! Rather than having to go and make such an explanatory recording, someone has already done it for us. Attached a picture of a fabulous Steinway Concert Grand (a Model D I think) - note how the strings run in different directions, the long low frequency strings running the full length of the case and at an angle to the mid/high frequency strings. This angular difference is the source of potential phasiness during recording mentioned in the next video.

                        Here is a video of a special microphone set-up sold specifically for 'getting under the lid'. The introduction is interesting as it highlights some of the issues involved in miking the piano. Note how extremely close the mics are to the strings - so close that there can be no pick-up of any room reverberation which is literally behind the mics and outside the physical box of the piano. So, as we'd expect, such a recording technique would give a completely dry sound - and it does.

                        A more conventionally recognisable microphone under the lid arrangement is here. Again close to the strings. Note that the video (correctly) describes this set-up as suitable for jazz piano, where that warm, intimate club dry sound is required by the producer. But maybe he'd like a little more air, and a little more piano body sound .... in which case pull the mics back 0.7-1m here. Or pull back even further and we have this sound.

                        One clip I must share with you because the music on the fabulous Steinway is so wonderful is here. Surely what the Steinway was invented for. On headphones you can hear that the bass strings are panned left, so what we hear is pretty much what the pianist would hear, L-R as he plays across the keyboard. Nobody in the audience would hear this L-R spread, so if you hear such an intimate, well-spread dry piano sound (complete absence of room reverberation) the piano must have been closely miked.

                        And here's an oddity: four pianos on stage. I can't see the microphones, but as we can clearly hear the hall and the piano sound isn't fat and intimate, by implication they can't be under the lid and close to the strings.

                        Finally, a piano correctly balanced against the orchestra with nice air around it. This perspective just wouldn't suit jazz - but it's what we're used to hearing in the classical concert. Also here - this is the sound I was aiming to capture in my own Fairfield Hall recording; I like the slightly distant perspective (microphones back from the piano) and lots of air, and crisp brightness (this recording is bass light though).
                        Attached Files
                        Alan A. Shaw
                        Designer, owner
                        Harbeth Audio UK

                        Comment


                        • #27
                          Alan - fascinating.

                          Thank you

                          Comment


                          • #28
                            Sound from close miking

                            After watching and listening to all the videos I have a better understanding of your examples of earlier posts. I have one question though about room acoustic and close up recordings.

                            In the past, I have noticed that my voice sounded very different in a over damped room. So if my ears were microphones, it is then picking up my voice directly and also the reflected sound from the wall hence I can feel the differences in my own voice in different environments. However, why is that microphones are said to be immune to room coloration if is extremely close to the source?

                            Does this mean the recording in Charter Oak e700 Microphone video would sound the same if recorded in an anechoic room with similar microphones and with a similar positions?

                            ST

                            {Moderator's comment: isn't this covered in Alan's posts that talk about the louder closer sound drowning out the further quieter sound?}

                            Comment


                            • #29
                              When is an echo not an echo?

                              Originally posted by STHLS5 View Post
                              ... I have noticed that my voice sounded very different in a over damped room. So if my ears were microphones, it is then picking up my voice directly and also the reflected sound from the wall hence I can feel the differences in my own voice in different environments. ... Does this mean the recording in Charter Oak e700 Microphone video would sound the same if recorded in an anechoic room with similar microphones and with a similar positions?
                              There must be at least two mechanisms at work concerning echoes (reflections).

                              First there must be the issue of relative loudness. The reason you can't hear the conversation on a table across a restaurant is because although the diners may well be talking at an elevated level, their voices are drowned-out (or technically, masked) by the other ambient noises in the restaurant. Second, there must be a time issue. When we talk of an "echo" it connotes to us a certain sort of experience where a copy of a sound arrives some time after the original sound at our ears, usually at a lower loudness and with some change of tonality. But imagine you were a mouse living in a corn field. If you've walked across a maize field it is an eerie experience, because no matter how loud you shout or how hard you clap your hands, there is no echo: it's an anechoic-like experience. But that mouse, quietly living amongst the stalks would have no conception of what an "echo" was. His acoustic world would be completely 'dry'. How would he cope with the cacophany of sound that his relative the city mouse survived amongst? So what we call an 'echo' is somehow related to our environment, something entirely outside of our bodies.

                              What we call an "echo" then can't be an absolute fixed experience. There must be (and there is) a time window outside of which a reflection back to our ear (or microphone) is deemed to be an "echo" and a reflection falling within that time window is deemed to be ..... what? By definition it can't be an echo, because we've already defined that as a copy of the sound falling outside the window. An echo can't be both something experienced outside and inside the window: we've defined it as one outside. So what is that 'inside timeframe reflection' going to be called? Can we call it any sort of echo or not? We really can't term it an echo at all. To be an echo it must be distinct from the source sound, and if it follows the source sound closely in time, it's not perceived as an echo at all. But it is nevertheless still collected by the ear. It has energy. It can't be ignored. It's real. And a microphone next to the ear connected to an oscilloscope would unambiguously register first the direct sound, and then the reflection.
                              Alan A. Shaw
                              Designer, owner
                              Harbeth Audio UK

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