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Kvalsvoll

Bulding the Room2 listening room

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And I'd love a pointer to a thread (couldn't find the one you referred to) on a velocity measurement kit to build or device to buy.

 

http://data-bass.ipbhost.com/index.php?/topic/404-understanding-and-optimizing-tactile-feedback/

 

I can send you a description on pm, the one that several others already have received. I just do not want to put it out in the open.

 

Don't worry about OT, that decent audio forums are dying is far worse. And this is on-topic enough, just today I have set up, calibrated, measured and listened to 4 different bass system configurations in Room2.

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Sorry to take it off topic with the sound velocity meter but I really didn't as I've noticed what you described above as well. Why does a 12" midbass have more impact than a 6"/8" midbass when played back at the exact same sound pressure level? I've asked multiple times, at least on AVS and I haven't ever received a satisfactory answer. I was hoping measuring the velocity would help point me in the right direction so I can understand this phenomena better. If you have ideas on the physics, I'd love to hear it.

 

And I'd love a pointer to a thread (couldn't find the one you referred to) on a velocity measurement kit to build or device to buy. Purchase depends on cost as well as if that will help me understand this size difference better. Thanks.

 

Exactly. The question is not IF the larger driver sound different, the question is WHY. Once that is established, we can move on and try to learn and find out what is going on.

 

I think there is at least two different causes at play here.

 

One is size of radiating area - the larger couples better to the air and creates sound with more intensity.

 

But capacity is also important. Even if they play at same spl, the smaller driver can be at its limits, causing dynamic compression of transients. This will not be audible as distortion before you turn it up much , much louder. But the peak level of the transients are missing.

 

I believe size is important from mid-bass and up into the midrange. At very low frequencies the size of one radiator is very small whether it is a 6" or a 24". But if you have 2 subwoofer units, they combine, and create a very large radiator together. If each of those units are very small, that does not matter.

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... a velocity measurement kit to build or device ...

 

@dgage, I sent you a pm several days ago with this, I saw today you may not have read it yet, you should be able to see it in your Inbox.

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One day I may elaborate some more on the velocity measurements - what is it useful for, what can you see and what is still missing.

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What can we see from the velocity measurements.

In addition to the normal spl we can get more information about what is going on when measuring the velocity. We can see the direction of the sound, resonances that does not appear on spl, cancellations of sound intensity.

Ideally, the v should match the spl across the whole frequency range. If we measure outdoor, we see that this is the case when there are no reflections or standing waves or room modes present.

In a room and with multiple sound sources, this changes dramatically. Here are 2 examples from the same room, 2 FL FR + bass system cf 120hz.

System with 2 V80 bass horns up front, spl and velocity in on-axis direction:

598a1e441830d_System12xV80front.png.b7e20b1f7dd628432c0d7914d6828fce.png

 

System with 2x V6030 behind, almost nearfield:

598a1e4d74688_System22xV6030backnearfield.png.2a645cf55061b231ce9605e09ca1d2da.png

 

We can see that the velocity does not follow spl at low and low-mid frequencies. This is caused by room acoustics and subwoofer locations.

The 2. has better v at very low freqs, and there is less v around 100-200hz. This may actually be due to the sound waves from the front main speakers meeting the same phase sound from the subwoofers located behind, causing v to cancel out while spl looks good.

 

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Looking at v in 0 (on-axis), 90 (sideways) and h (vertical) directions gives information about the direction of the sound.

Direction reveals where reflections come from, and indicates the intensity of the sound. High intensity sound is directive.

Here we can see that the 70hz spl dip is caused by reflection from the ceiling, because h direction v has a top in this same range.

Up through lower midrange the sound field becomes more directional and resembles the outdoor free-field situation.

Above 1K the measurement device is no longer valid.

At low freqs the velocity drops, and that is not a good thing. But there is not much that can be done with that, unless one is prepared to do structural changes to the listening room - moving walls, closing off the open side wall door. For music it does not matter that much, and the low bass (<20-30hz) is experienced as airy, powerful, tactile. Sound intensity is the vector product of velocity and pressure, and there is plenty of energy to move the floor enough to create the necessary tactile feel.

Sound intensity is what drives tactile feel, and vibration of objects. If we eq this spl response to flat - such as removing the 70hz dip, it will not sound more flat and balanced, because we induce too much velocity and intensity in the sound field in the range that already has a velocity resonance.

598a2383a9fed_System12xV80front090h.png.dfd8ca3fccec37fc153aa27eb957d4ae.png

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System 2 with subwoofers units located behind - spl is more flat, it does not extend very low, velocity is very different.

V6030 is tuned much higher, so it is limited to around 25hz, and the placement is very bad for low bass.

We see the v at low freq is much better, overall the v is higher in the bass range. This is expected, the units are quite large acoustically, so you are actually in nearfield in the listening position.

We observe the same vertical 70hz resonance, so moving the subwoofers did not change the room. Some effects are due to the room-listening position interaction - will not change, others are caused by speaker boundary - changes when speakers/subs are moved.

100-200hz there is a dip in v, this would have to be investigated further to make this into a resonably good sounding system. First would be to find out what cause this, a new meas with fronts off would reveal if it is the interaction between front and subs causing the problem. It is not spl, phase, timing related (which you would see if you have the .mdat).

This system does not sound good. You can easily hear bass coming from behind, and even though the tactile is quite strong, it does not feel right, something is missing, and it does not sound well integrated and coherent.

Can you hear direction of bass? No, not below around 100hz, but the subs on cf 120hz will emit sound much higher up in frequency.

Can you feel direction of sound? No, and yes. Very close to the sound source you can feel it, and I conclude due to the velocity and intensity being higher on the side of your body facing the sound source - now we are talking about sound that has so large velocity that it actually feels like wind on your body. Direction in itself is not perceivable, and once you get reasonably far from the source, you can not detect direction.

(image hosted on my web)

System%202%202x%20V6030%20back%20nearfie

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Seems I have posted too much, there is a limit to attachment uploads so I can not post the graphs. Solved by hosting images on my web.

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Different subwoofers up front gives a different result. Swapping the V80 units for very small V6 shows no significant reduction in velocity when the sound source now is half the size acoustically.

The difference in response (spl) and velocity are mostly caused by different location of the sub units, and the smaller ones roll of much earlier.

At louder spl levels it is obvious there will be a difference where the larger V80 has the advantage, but the V80 system also sounds better at low volume. Having a large system makes sense even if the capacity is never put to use.

System%203%202x%20V6%20front%200%2090%20

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The Room2 is a test and demo room, but it is also where I listen to music most.

So I want to share with you what music I played in a short listening session this evening, music examples are something I always find very interesting and useful, so perhaps someone finds inspiration for new things to listen to. I suspect many of you have never heard about none of these.

 

1. Voices of Music - La Folia.

The long 10 min one, with the dancers. The F2 speakers allow for a little louder master (-3dB) than you would experience in a live performance for this sort of music, but that makes the realism better, especially when the dancers stomp the scene floor - the recording is full-frequency-range, so you actually feel the scene floor moving.

2. Voices of Music - La Folia.

A different version.

3. Flashbulb - Piety of Ashes.

New release, only one track available as preview. Excellent, this is something quite different from the baroque ensembles. Master 0dB.

4. Flashbulb - Soundtrack To A Vacant Life, tracks 4, 5, 6.

Excellent music, excellent production. This is electronic music, with a complex and detailed sound landscape. Bass is physical and tight. Master 0dB.

5. Jøkleba - Jøkleba!  Nu jøk - Girl, Firefly.

Jazz. Very dynamic recording, heavy and tight punch from the large drum, trumpet so present and rendered with such clarity you can see the fingerprints on the brass. Master +3dB.

6. Daniel Herskedal - The Roc - 07 The Afrit, and 08 There Are Three Things You Cannot Hide; Love, Smoke And A Man Riding On A Camel.

Jazz. Herskedal experiments with his tuba and creates a musical journey. Again - bass is physical, and the drums has this realism you otherwise only get at a live concert. Master +3dB. 

7. Hadouk Trio - Utopies, Shamanimal Live.

Jazz. Here the V80 horns excel in rendering the deep, powerful bass tones. Master +3dB.

8. Jøkleba - Jøkleba!  Nu jøk - 16 - Schopenhauer.

One last jazz track. Master up to +6dB for a truly visceral experience on this relaxing masterpiece.

 

The music can be found on Bandcamp and Tidal. Voices of Music on youtube unfortunately, make sure to get the best possible quality on the audio stream.

Current equipment in Room2: F2 main speakers and 2x V80 compact horn bass-system.

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Today I listened to some albums I found yesterday, when it was too late to play at realistic volume.

First some brass-band music, that I would normally never listen to. But the experience makes it so captivating, I just have to listen to one more track. Is it like the real thing? Honestly, how can I know. The individual instruments are here, placed on a scene in front of me, inside a room much larger and with very different acoustics from the Room2 I am physically sitting in. The recording renders instruments and room from the recording in a way that does not sound like it comes from 2 small speakers.

So, this must be a very spectacular recording, with very special qualities?

Fact is, most recordings share many of those properties - individual instruments rendered with true physical size, lots of space and room from the recording. They are different - tonal balance, clarity, dynamics, bass character, room, instrument image. The presentation takes on the character from the recording.

Why is it so.

Room acoustics and speakers. The radiation pattern of the speakers and the acoustic treatment in Room2 together makes this. Early reflections are suppressed across most of the audible frequency range, while later reflected energy is allowed to contribute. It is the removal of early reflections that creates the clarity and separation, while the later reflections contributes to amplify the room information from the recording.

To be able to move on, to improve things further, this is a starting point. How long does the ISD-gap need to be, is it enough to suppress reflections below around -35dB within the gap, what about frequency range for the gap? Do we need horns? How large horns do we need? What radiation pattern should we choose? What about the reflected energy after the ISD - how strong, how fast should the decay be?

Then there is transient response. We often call it dynamics, but that is strictly not the same as being able to reproduce percussive instruments with realism. This is where, in my experience, all typical hifi-speakers fail most. A bigger speaker, with more capacity and more directivity control, with drivers that has much better transient response, is in a different league.

In this context - how do we compare and rate speakers. How can we set up a controlled (which implies at least blind) listening test to evaluate and compare speakers. It may be necessary to do tests focused on a very small subset of properties, so that a complete evaluation needs several listening tests, which then after can be combined to make some kind of overall measure of sound quality.

 

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There are a few Cirque du Soleil recordings that are on Youtube, you might have to search for good uploads. Having attended a few of the shows in person, I have to say that the recordings are very good representations of the actual events.

 

 

 

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Kvalsvoll, have you tried any of the Danley Sound Labs recordings? http://www.danleysoundlabs.com/tom-danleys-mic-recordings/

A friend of mine who has spent many hours behind the handlebars of a shovelhead was downright shocked at the realism afforded by the recording of Donny's Harley. You could 'feel' the individual cylinder pulses from ~ 4 meters away. I tried uploading the zipped file, but it exceeds the attachment limit.

 

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1 hour ago, Ukko Kari said:

Kvalsvoll, have you tried any of the Danley Sound Labs recordings? http://www.danleysoundlabs.com/tom-danleys-mic-recordings/

A friend of mine who has spent many hours behind the handlebars of a shovelhead was downright shocked at the realism afforded by the recording of Donny's Harley. You could 'feel' the individual cylinder pulses from ~ 4 meters away. I tried uploading the zipped file, but it exceeds the attachment limit.

 

I have some of the DL clips from a few years back, they are great.

I assume he just put up 2 mics, not the usual ones used for music recording, but full frequency-range, recorded, and that's it. If you have a capable enough reproduction system, you will hear the actual event. If you have limited headroom, it will not be anything special at all. Sound effects in movies are usually very different - they are dynamically compressed, peak limited, and too often high-pass filtered. Often they are colored by eq to make it sound "better" on equipment with limited low frequency extension. All this processing allows for louder and more powerful sound when speakers have limited headroom, but unfortunately all realism is gone.

Youtube-clips can be fine, if for nothing else to preview music before you decide to buy it. And quality is very variable, you have to search for usable quality clips. Some have quite decent quality, but still everything is limited to the 125k aac compression. I mostly use Tidal nowadays, easy to find music, and quality is not an issue.

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4 hours ago, Ukko Kari said:

Kvalsvoll, have you tried any of the Danley Sound Labs recordings? http://www.danleysoundlabs.com/tom-danleys-mic-recordings/

A friend of mine who has spent many hours behind the handlebars of a shovelhead was downright shocked at the realism afforded by the recording of Donny's Harley. You could 'feel' the individual cylinder pulses from ~ 4 meters away. I tried uploading the zipped file, but it exceeds the attachment limit.

 

The Harley recording is great, and I too have felt the concussive effect of each cylinder firing on my system at home, at 3 meters instead of 4.  It is a fantastic demo of realistic dynamics.

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21 hours ago, Ukko Kari said:

There are a few Cirque du Soleil recordings
...

 

 

Found them on Tidal, not my type of music, but always worth checking out what others like too. To me, the last album had better sound, they are all quite loud and sounds best at lower playback volumes.

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Tested movie multichannel in Room2 on the 2-ch system - quite good, only there is one huge drawback.

Purpose is to play multich movie on a 2ch system, and still enjoy surround sound.

How I did this: Send full 7.1 on hdmi from the computer, select Movie mode on the processor, select Virtual on the processor. The processor then maps the surround channels from the input signal to the 2 front channels, so that sound from sides and back appears to come from sides and back, played using only the 2 FL FR speakers.

Test it using the 7.1 channel check clips from dolby or dts, if it works the surround channels will appear somewhere at the sides and back, more or less.

This of course requires that you run a AV-processor/receiver on the 2-ch system.

And it works, surround sound is immersive and quite decent, though not comparable to a good multich setup, the surround images are much less precise, and in Room2 it does not work so well for sounds behind lp. Tested this on some of the atmos tracks, and movies.

The drawback? Very small sweetspot, if you move your head the whole thing collapses. So this is a one-person-only solution, that you can use if you don't want to mount surround speakers. And to truly enjoy a movie, it is preferable to have some sort of screen to show the picture in front of you, which I do not have in Room2.

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I used to do that sort of thing a long time ago when I used a Linux PC for DVD playback.  The player had surround virtualization built-in.  The effect worked a lot better with headphones, and there were times in which I actually played the movie with the stereo on (so I could feel some bass) *and* the headphones on my head.  Yeah, that was a while ago.

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@SME no wonder it worked better with headphones, because it is the phase difference between the l-r channels that places the sound, and in a typical room this phase difference is disturbed by room reflections.

This is also why it works only in one location, when you move the head you also change the phase between the 2 channels.

Physical properties of our head and ears reveal how we can determine position of a sound source. A sound from one side reaches one ear first, the sound continues to travel around the head and reaches the other ear. The psychoacoustic perception mechanism in the brain interprets the time difference to determine where the sound comes from. At very high frequencies it is mostly level difference detection, in midrange it is phase, and at very low frequencies we can not hear direction because the phase difference is too small to be detected.

Then we can also understand why we can not really hear height or whether a sound comes from directly behind or front. But how come we perceive to hear both height and distance and size of sounds?

Height can be perceived if the sound object moves, because the frequency response of the ear changes with vertical direction.

Sound stage, depth and so on are complex. Location of sounds is helped greatly from reflections, and here the resulting sound we perceive is a combination of the sound from the sound sources on the recording, the reflections from this source on the recording, and the reflections we get when we play this through speakers in a room. Now we can easily hear if the sound comes from behind. Transient sounds are much easier to place, because the hearing mechanism detects the time difference between the first sound and reflections, and uses this to get an idea of where the sound came from.

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This is why we have sound systems:

 

Easily album of the year.

Each Flashbulb album has its own characteristic sound - both musically, and how it sounds.

Within this framework of sound, there is diversity and contrast, exploring the limits of our perception of sound. Elements in the sound appear all across a huge, wide soundscape, with clarity and precision that makes you see textures and patterns in 3 dimensions.

Music like this is one reason why spending big money on sound makes sense because it pays off in great experiences.

https://theflashbulb.bandcamp.com/album/piety-of-ashes

a3182957404_16.jpg

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I like the compositions in the album quite a lot.  The bass in most of the songs is of very inventive design, unfiltered, and tremendous.

With that said, I think it would be better with a lot more headroom (like +10 dB or more, ideally), not unlike most music releases.  It's necessary in order for the tracks to share well with the intense bass that's present.  Pumping was apparent throughout and at times extreme, and while at times it may have been intentional, I didn't feel that it always worked musically.

Apart from that, I noticed a grainy harshness to the highs that I've noticed with other stuff from the artist that you've recommended.  The nature of the sound is rough and edgy and lacks the silkiness and air that a good master has.  I'm only guessing here, but it sounds like there could be peakiness somewhere in the 5-12k range and poor extension beyond that range.  I've noticed some mixes like to put peaks in places in the treble to "bring out detail", and I guess that tactic might work on speakers that are otherwise recessed.  It's also possible that the edginess arises due to clipping or some limiting strategy.  I'd have to download the tracks to inspect for clipping.  Other than that, it's possible that the problem exists or is worsened by digital lossy compression.  Usually Bandcamp streams are reasonably HQ, and I rarely notice blatant artifacts.  But who knows.  I'm just trying to cover all bases.

Anyway, is it just me that hears this harshness?  Honestly, I don't find playback beyond that which I use for standard "loudness war" stuff to be comfortable to the ears.  That's still enough for some powerful bass though.

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12 minutes ago, SME said:

I like the compositions in the album quite a lot.  The bass in most of the songs is of very inventive design, unfiltered, and tremendous.

With that said, I think it would be better with a lot more headroom (like +10 dB or more, ideally), not unlike most music releases.  It's necessary in order for the tracks to share well with the intense bass that's present.  Pumping was apparent throughout and at times extreme, and while at times it may have been intentional, I didn't feel that it always worked musically.

Apart from that, I noticed a grainy harshness to the highs that I've noticed with other stuff from the artist that you've recommended.  The nature of the sound is rough and edgy and lacks the silkiness and air that a good master has.  I'm only guessing here, but it sounds like there could be peakiness somewhere in the 5-12k range and poor extension beyond that range.  I've noticed some mixes like to put peaks in places in the treble to "bring out detail", and I guess that tactic might work on speakers that are otherwise recessed.  It's also possible that the edginess arises due to clipping or some limiting strategy.  I'd have to download the tracks to inspect for clipping.  Other than that, it's possible that the problem exists or is worsened by digital lossy compression.  Usually Bandcamp streams are reasonably HQ, and I rarely notice blatant artifacts.  But who knows.  I'm just trying to cover all bases.

Anyway, is it just me that hears this harshness?  Honestly, I don't find playback beyond that which I use for standard "loudness war" stuff to be comfortable to the ears.  That's still enough for some powerful bass though.

Level is pushed quite hard on this album, and on some tracks it clips, very easy to hear when you have a system with high resolution. I really can not know whether this was intentional, he uses different distortions and added noise as part of the artistic impression. On Soundtrack To A Vacant Life he uses distortions, noise and bandwidth limitation on some tracks, to create a special sound.

I found the pumping quite annoying on one of the tracks, I believe this is intentional, it is supposed to sound like that. We can like it or not.

I don't find the sound on this album to be harsh, part from the obvious clipping it sounds more like smooth and soft. Many newer releases actually can sound a bit harsh, at least noticeable when switching between albums in a session. This can be because they wanted this sound, or simply a result of too much limiter, which will cause distortion. Compare say Yello - Stay to any typical jazz with vocal recording, Stay sounds more harsh, distorted, not smooth.

I often find it quite easy to listen "through" obvious faults in a recording, because they stand out as separate sound not part of the music itself. Recordings and productions have faults, and I have found it is easier to ignore faults in a system that reveals everything with clarity, as opposed to a system that tries to mask and cover up.

This album is not very loud compared to other things out there, master at 0dB works fine, actually required to get the full effect of the bass.

Bandcamp delivers flac lossless, so that's a non-issue.

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