Yes, I agree, to ensure continuity when hearing, they need to flatten the variation of 1)amplitudes and 2)directions of harmonics. It should be quite difficult to make a "seamless pasting", considering the 2 dimensions of the problem... Probably a painful random bricolage, ending with a massively processed sound more easy to paste...

This picture is for me the confirmation that the "physical presence of sound", is still different between AP and DP. Spatialization of sound (both during recording, and playing) is really important, to capture liveliness and depth of a tone (the harmonics "swing" and roll in the box). Other point is filtering low and high frequencies is also limiting the perception of vibrations of the piano by our body...

dewster,

Do you have some pan view of a note played on an accoustic piano ? I am very interested to compare, with DP samples. This stereo panning is really intriguing for me.

Do you know where it comes from, it is a slow directional sound motion with back and force, nothing that can come from a reverb, so seems to be a mobile sound source : sound board ?

For me this is the vibration of the sound board inited at oscillting string fix point, and making wave in the sound board. Correct ?

I previously did a comparison between Roland SN, Kawai UPHI, and a fully sampled Yamaha C7 from VintAudio here.


I believe the slow, rather random pan is mostly from having three unison strings tuned slightly differently beating together in close proximity to each other on the soundboard. Some of it could also be the primary modes of excitation rotating around the axis of the string. I haven't extensively researched what causes this but it is certainly there on a real piano and short loops understandably kill it every time.

Thanks, perfect

Dewster, I am lost...
Please try again (differently ), I really want to understand that...

Perhaps slow traveling mode (emerging from quick stationary modes) :
http://www.youtube.com/watch?v=GMXlzCX5gio

Or what about stationary vibrating modes drifting or being instable (between 2 modes) :
http://www.youtube.com/watch?v=GtiSCBXbHAg&feature=related

Look a this increadible cimatics example with human voice :
http://www.youtube.com/watch?v=KU84ckD1AcA&feature=related

When you play a note on a piano, except for the lowest bass notes, the hammer hits more than one string. Most notes in fact have three strings. These strings are tuned almost exactly the same, but the slight difference produces a slow moderate phasing sound.

Another thing that might cause this phasing is the direction the strings are vibrating. On a grand piano the hammer hits the strings vertically, but during the decay I think the vibrations can slowly rotate around to horizontal and back again to vertical.

Thanks

dewster,

Phasing sound is a "new" sound, with its own lower frequency.

In your pan view, all the curves are moving. If it were phasing sound, as 1 note is played (max 2 strings vibrating), at most one or 2 phasing sounds could appear and slide. Or, all harmonics will generate there own phasing sound. But even in that case, some curves should remain static (that is at least 2 statics harmonics for 1 phasing sound).

Other thing that is strange, the moving frequencies change of direction (inflexion) in random area. I am not sure a phasing sound can do that.

Actually eitheir moving wave reverb (or not) against the edge of the soundboard, or at against soundboard barriers. Probably barriers are like guide for "almost"stationary modes (like guide for chaldni nodes in guitar sounboard). Or this "quasi" nodes moves really "randomly"...

I don't know, I don't understand...

When you add together three sine waves with slightly different frequencies, the result can be a somewhat random looking wave. This is essentially what's going on with the piano notes: their stereo harmonics sum together to make new harmonics with a somewhat random stereo image. This harmonic sum appears as a single line in the spectral pan view, drifting up and down in the stereo field. I'm sure some coupling is going on through the soundboard as well. It's all rather complex in real life, which is why it's probably best just to sample this stuff than to simulate it.

I think I understand a little bit more.

I imagine the 3 strings vibrating at almost the same frequencies, and almost the same phase, coming for almost the same place.

All these sources (without considering coupling for the moment), generates waves in the sound board (either starting from a point or a segment, depending of the rigidity of the chevalet (where string are fixed), so circular waves from spot, or transerval waves from segment.

These is true for all 3 fundamental waves, and all 3 waves per harmonics transmitted by string (not considering sound board is an "active" transmitter, and may modify waves (take more energy for some, re-create new upper harmonics, etc).

All these waves are moving 5000m/s in sound board, rebounding (reverbing) against edge, then as edge are not regular, all these echoes supperpose together.

We have then complex interference pattern beating, increasing amplitude in some place, decreasing in another place, and probably, these patterns (with high up front), still beating at harmonic frequency, due to slight phasing effects, can begin to drift a little (1m per second or so) in random direction in the sound board, in the beating mesh, creating stereophonic effect...

Is that description correct ?

PS : I want to understand how complex is the modeling of sound board...

Regards

And sometimes, for certain frequencies, all interference pattern (or at leat for fondamental) stabilize/synchronize together, and we get a chaldny stationary mode ?

Still correct ?

I'm looking seriously at the Kawai CS9 which also has UPHI - is this going to be exactly the same results in terms of Attack sample length as the CA63 test you have done? Slightly dissapointing if so as the Avant Grand is a few seconds better for most of them Please let us know.

Kind Regards,
Allan

Good question. If you can get near one long enough to render the DPBSD MIDI to MP3 to I'd be able to tell you. From the manual:

http://www.kawai.co.jp/worldwide/support/manuals/pdf/CS9_EN_20110613.pdf

Page 45 describes how to convert a MIDI file to an MP3. All you need is a thumb drive with the DPBSD MIDI file on it. Kawais generally have quite nice stand-alone rendering abilities, kudos to them for that.


The DPBSD testing for me has been one long trail of tears with only a few bright spots here and there. The products seem to be improving, but so slowly only a turtle or a great sequoia might notice. We haven't quite reached the "big shakeup" in the DP market (when unlooped & unstretched high-end models will be the norm). As with all computing equipment, if you can afford to wait you can likely get more for less later.

2 dewster
Just have seen your begging section.
Well, I have LIMEX Vienna Grand Piano expansion board. And I'll try to post here the result mp3. I am sure the expansion board has the same chipset as the piano module.
Just two words: ATSAM9708 + 256MB + 3xPCM1754 + AL3201B. No magic.

SOMEWHERE there are some slow mo movies of this.
The closest description I can offer is that it is somewhat similar to the motion that I have seen in a skip rope when a child at one end swings it in a circle.
Not really a "traveling screw" wave motion, but certainly more than merely vertical.
As I recall the explanation given was that the initial vertical motion "collides" with sound energy from the soundboard, which deflects the string vibrations, resulting in some horizontal component.

This was a long time ago, the details escape me, it may still be found with a well crafted search (-:

Hokey-smokes, I had no idea anything like the ATSAM9708 (dual DSP / GPU to support 128 polyphony + effects) even existed outside of the proprietary realm, thanks for that! The AL3201B (digital reverb engine) is also a very interesting part.

I'll gladly take your MP3 whenever you might be able to provide it.

The thing that really put me in a confusion is a 2$ DAC onboard. It spoils all the impression here, don't you think so? When it comes to a compact layout, AD1854 of my RP-X takes a slightly more space.

The PCM1754 looks nice enough on paper. Certainly DACs these days are lightyears ahead of what we had just a decade or so ago, and with DACs showing up in literally everything price may not necessarily be a good indication of performance. Beyond hearing some aliasing when trying to reproduce high frequency, high amplitude sine waves with my old PC sound card, I can't say I've ever directly experienced a "bad" DAC. Perhaps I'm not able to hear it for some reason, or the opportunity just hasn't presented itself?

It's been said that the very worst DAC is better than the very best speaker.

Greg.

Absolutely. Though it's kind of amazing speakers have been refined to the point they are currently. Who'd think a piece of paper set in motion by an electromagnet and placed in a box could sound so good?

The most likely limiter of magic on the LIMEX Vienna Grand Piano expansion board magic is this: 256MB

Dewster,

I think what you are referring to as a "phasing sound" might be more appropriately called a "detuned sound", according to your description of the effect as a by-product of slight detuning of the three strings.

To an audio engineer, phasing is technically something slightly different. As you probably already know, a phase shifter takes the dry sound and mixes it with a wet sound that is in a constant state of time shift (induced by speeding up and slowing down the sound slightly), at a certain modulation speed. As the shifted signal comes into phase with the dry signal there is a notch where certain frequencies go away almost completely, and it feels like your head is collapsing in on itself. The key here is that there is modulation involved. The wet signal is slowing down (getting very slightly flatter), then speeding up (getting very slightly sharper), but in reality with a phase shifter sound, the detuning isn't usually enough to to be perceived as pitch shifting. If you play with these parameters on a time delay program, widening the modulation and amount of time delay will take you from phasing into chorusing.

But in any case, the piano strings are not modulating - they are each staying in tune as they know it, and the beautiful sound produced by all three together is what an audio engineer would call detuning.

But I know what you're getting at, and for street lingo, "phasy" is not too bad of a description.

Really enjoyed reading all of your DPBSD stuff, by the way - extremely informative. Nice work.

-Wes

In re-reading the various posts on "panning/phasing" etc.

I think it is as much that a) the string excites the board b) then the board gets out of phase with the string c) the board feeds back to the string and excites it d) the board gets back in phase with the string again (repeat loop).
Bearing in mind that the strings themselves are NOT producing much sound and that there are (as dewster has said) more than one string per note - and more than one note sounding at a time.
A dozen, two dozen strings, all quasi randomly exciting then suppressing the soundboard by being in and out of phase with it.... Yeah, I think my head wraps around that as a model
Now if I could just wrap the math around that model, perhaps Viscount would employ me on the physis project ? (-:
(perhaps, but VERY unlikely)

Yeah, "phasing" is a term that means something very specific to an audio engineer, and I don't mean to abuse it. But I'm not sure how else to describe the sort of gentle swirling sound in the decay of a real (i.e. fully sampled) piano note. "Detuned" is more accurate as to the root cause, but perhaps has a negative connotation?

I'm glad you've found something of use in the DPBSD testing Wes!

Heck, if someone could just sufficiently sample the thing I'd be pretty much out of a job on this thread. We have the equivalent of severed, crawling hands posing as full healthy bodies in most DPs.

Re: "phasey", I think we're really splitting hairs here. I would have used exactly the same word in this context. The "phaser" effect could also be called a "detuner" too, because whenever the delay time of the delayed versions of the input signal are changing, the pitch of those delayed signals is necessarily different to the input.

Greg.

I think the phaser effect is similar to, but not the same as 'detune'. In practice, they usually overlap, as effects:

The 'phaser' effect usually means two or more versions of the same signal but beginning at a slightly different phase of the wave (signal one: zeroº and signal two, 70º or 90º, etc etc). This causes a 'band reject' effect as the waves' sum: sometimes = x2 but at others, about zero (the one cancels the other out at certain points of the phase).

However, 'phasers' as musical effects are almost always dynamic, in that the distance between the two (or more) signals is constantly changing (with a LFO (low frequency oscillator), usually). That does not, as far as I can think, involve actual detuning.

However, a similar 'phasey' effect is obtained by having two (identical or similar) signals playing very slightly out of tune - simply because the phase length (frequency) of one is going to be shorter than the other, so the 'phase' of each finishes at a slightly different time, and so on until both get to start at zero again. In other words, 'detune' gives you a kind of automatic phasing.

Indeed, the early 'Harmonisers' in the 70's and early 80's worked by having two or more coordinated 'phasers' to give the impression that the input signal was not only being split in two but also detuned against itself.

Um - I hope that's clear....and correct...

Agreed - that's my understanding too.



I think it must involve a change of pitch (however slight), because the only way to alter the relative phase between the input and "phased" signal is to alter the speed at which the phased signal is sent to the output. If the speed(pitch) of the phased signal is kept constant, and at the same speed of the input, there will only be a constant delay, and thus a constant relative phase difference.

Greg.

Yes, exactly - you can get a 'static' phase effect with no change of frequency. But it's not often used as a musical effect, although it does exist in real life (stamping your foot in an alley way or back entry, for example).

So of course you are right because the usual musical phase effect does involve detune or simulated detune (ie continuously changing phase shifts causing slight and changing shifts in pitch). It is, after all, a nice thickening effect imitating three piano strings or even string sections....hence the word 'Chorus Effect' for a similar device.

Question: do the best piano tuners actually set the strings out of tune with each other, or put them perfectly in tune? My guess is that they would put them as closely in tune as possible which would result in very slight phase shifts due to......what ever.

(amended reply)

LIMEX Vienna Grand Piano Expansion Board Review



This is a sample of a fairly obscure piano module, and the first submitted by PW forum member "galaksa".

PIX: http://www.mediafire.com/?wa7bb0zw6etfv4v
MP3: http://www.mediafire.com/?yuc2a1v8qewc36j

The concept behind this board is one that appeals to me: a module with most of the ROM dedicated to piano, and available as an expansion board or mounted in a box. The world could use more straight-up piano sound modules. This particular board employs ATMEL ATSAM9708 dual DSP / GPU to support 128 polyphony + effects - it was something of a shock for me to discover that something like this even exists outside of the proprietary realm. The wavefront AL3201B digital reverb engine on the board is also a very interesting part.

The distinguishing feature of this module is that it is unlooped. But the way this is accomplished is by making the note decay times really, really (really!) short. Notes sound like someone is quickly turning the volume down after several seconds. Don't quote me, but I think I'd prefer a bit of looping here to lengthen things. Or perhaps the removal of several layers, with the resulting freed up memory (LIMEX says 240 MB) used for longer decays. Heck, I'd take more stretching if it could add anything to these unnaturally fast decay times. The real solution here is of course more ROM containing a larger sample set, but good luck persuading DP manufacturers to go that route.

The other distinguishing feature is that it fails almost all the DPBSD tests. If manufacturers are going to give us such highly compressed fare, I at least expect some realistic pedal / key behavior to make up for it, but you won't find that here. It does have 7 velocity layers, but they are unblended and one of the transitions located somewhat above the center velocity is quite abrupt sounding. It's also fairly stretched. There is some kind of pedal sympathetic resonance going on, but it's on the threshold of audibility and therefore essentially moot.

Some analysis pix and text review:


Figure 1. Waveform view of the entire looping test, vertical zoom applied to see the noise floor. The decay rate is ultra fast, probably the fastest I've ever encountered and extremely fake sounding.


Figure 2. Spectral pan view of the stretch test, low end of the notes, normalized to -1dB to increase clarity. Stretch group transitions are audible over the low and mid notes, with inconsistent stereo L&R pan making some transitions even more audible.


Figure 3. Spectral frequency view of the layer test. There are 7 unblended velocity layers both visible and audible, with the transition at v=92 sounding quite abrupt.


--------------------------------------------
- LIMEX Vienna Grand Piano Expansion Board -
--------------------------------------------
FILE & SETUP:
- dpbsd_v2.0_limex_vienna_gp.mp3
- LIMEX Vienna Grand Piano expansion board.
- Preset "7-layers Grand Piano".
- M-Audio Revo 5.1, vanBasco's Midi Player, Steinberg WaveLab.
- Recorded by "galaksa".
PROS:
- Pedal sympathetic resonance of some sort but it is exceedingly subtle.
- Unlooped, but the samples are way too short.
- This is an unblended seven velocity layer sample set.
CONS:
- Fails the key sympathetic resonance test.
- Fails the silent replay test, note damps @ pedal up.
- Fails the quick damping test, note damps with quick pedal.
- Fails the late pedal partial damping test.
- Fails the half pedaling test.
- Ultra short note decay time, low notes ~10 sec, mid ~5 sec, hi 2 sec.
- Fairly stretched, and audibly so, particularly in the low and mid notes.
- Some stretch groups have inconsistent stereo L&R pan.
- Stretch distances: 6,3,2(x3),1,2,3(x3),1,3,2(x4),1,2,3,2,2,3,3,2,2,2,3,2,2,1,4,3,2,2,3,5 = 41 groups.
- Velocity switch @ vel=42,60,76,92,106,118.
- Velocity layer switches are visible and audible, the switch @v=92 is particularly jarring.
OTHER:
- Notes played @ vel=1 produce sound.
- Dampered | undampered transition: F6 | F#6
- Dynamic range 48dB (vel=1:127).
- MP3 levels: peak @ -1dB, noise floor @ -74dB.
- Date reviewed: 2012-05-23.

Thanks for posting the review.

I'm curious, what exactly does this expansion board plug into? Is there some kind of controller/rack product capable of taking a selection of different boards?

Also, I note that there are several other piano voices available - do you suspect that they are the same core sample with filtering applied, or is separate wave data being used? Did you manage to calculate the approximate sample data size, based on the stretch groups, decays, and layers?

Cheers,
James
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