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Re: Grand Imperial string res noise.

Postby pterm » 13 Sep 2017, 08:25

I don't hear a "click". I do hear a short "buzz" on the higher velocity string resonance examples, but this is what I expect: String resonance excites unplayed strings that share harmonics with the played string, so some additional noises are to be expected. The buzz I hear occurs just after the key strike.

I also looked at the spectrogram in Audacity and saw nothing out of the ordinary. Clicks indicate a discontinuity in the audio signal and are characterized by a large instantaneous (or near-instantaneous) change in value. I heard some when I played a segment of the audio, but these occurred at the beginning and end of the segment where the sample began or ended with a large non-zero value. This artificially introduced a discontinuity. I heard no clicks in the middle of any segment I listened to.

The frequency content of a click is "broadband". This means it contains energy at all frequencies, so when you say you hear a click in a narrow band (5200-5400Hz), it indicates to me you heard something not normally considered a click.

I don't thing you're crazy. I think you hear something subtle: perhaps a natural characteristic of the sampled piano or an artifact introduced by the digital sampling/re-creation of the signal. If you can isolate what you hear to a shorter recording and define a time stamp (from your DAW), we can look at the signal waveform and spectral content and maybe figure out what it is you hear.

Thanks for bringing this to the forum -- I enjoy trying to analyze things like this.
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Re: Grand Imperial string res noise.


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Re: Grand Imperial string res noise.

Postby cleito » 13 Sep 2017, 14:35

I used an EQ plugin in 5300hz and lowered all the other frequencies.
Also the file now is in wav format. Maybe it will change something?
About the spring noise I know its normal, but I don't thing its it. I only found it in those two keys.
Again, the notes are C (no problem), C# (with click), D (with click).
played 2 times this sequence and the third has the string resonance off and no click.

This is the raw file, no EQ, but in wav now.
nord Grand imperial noise.wav
no EQ
(14.23 MiB) Downloaded 120 times


This is the file with EQ at 5300hz.
nord Grand imperial noise EQ.wav
with EQ
(14.23 MiB) Downloaded 100 times


mp3 size was 800kb. Wav is 14mb.
Hope you guys can hear it now and see if its normal. :thumbup:
(I tried the mp3 player but it does not work with wav, maybe adding a wav player here too?)
Last edited by cleito on 13 Sep 2017, 14:41, edited 1 time in total.

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Re: Grand Imperial string res noise.

Postby baekgaard » 13 Sep 2017, 18:57

OK, it's audible now. It is, however, quite faint...

I looked at the spectrogram, and the one that is OK looks like this (taken from the equalised version, showing 0 to around 10-12 kHz linear here, and a time of around 4 seconds):

Image

The one that is NOT OK (and where the click is clearly audible) looks like this:

Image

I had to increase the gain 32 dB, though, to hear it/see it on my speakers. But it's now visible in the filtered band.

The non-equalised version looks like this (after an additional 12 dB gain and some careful tweaking of parameters to make it stand out a bit):

Image

and the click is aso visible there around 5-6 kHz -- although I don't hear it on my small Genelecs.

One temporatl location of the click is from 10.343s to 10.360s -- but the waveform looks reasonably "normal" to me (I don't see any immediately abnormal jumps).

I've also created a version that has a bandpass filter in the range of 4kHz to 8kHz. It amplifies +30dB in the filter region and dampens some -114 dB (!) outside, so there's almost nothing left but the "click".

The link is here http://b4net.dk/tmp/nord_Grand_imperial_noise.mp3.

In the filtered range, there is a "ringing" in the OK sounds, and I think the "click" is actually just the very start of that "ringing", and then the rest is not part of the loop (or something). So maybe it is a combination of a slightly unlucky loop-start or blending of two samples or something.


I'm quite sure that I would not hear this in normal playing, though :-) To make it audible, I had to do some quite heavy processing... Of course, once you know it's there, it may be noticeable with good cans or inears, but I didn't have them here with me. But I'll happily keep on playing the Imperial Grand :-)


Hope this helps?


-- Per.
Last edited by baekgaard on 13 Sep 2017, 19:06, edited 3 times in total.

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Re: Grand Imperial string res noise.

Postby pterm » 13 Sep 2017, 19:13

Clieto, thanks for the updated files.
Per, thanks for the great analysis. The artifact is clearly visible, so good news: Clieto is officially sane! ;-)

I plan to look at this evening and see if I can spot anything anomalous in the waveform and I'll keep playing the Imperial Grand too.

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Re: Grand Imperial string res noise.

Postby cleito » 13 Sep 2017, 20:20

Thank you guys for all the replies and I'm happy that I'm not going crazy :p
I use the Grand Imperial for like 3 years, I don't know, since it was released and this is the first time I heard that click while playing and I was using hall reverb. But this happened because I used the iPhone phone and that thing don't have a lot of low frequency like the porta pro Koss, maybe that helped me to hear it.
I will keep using the Grand Imperial of course, I just was surprised to never have heard it before.
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Re: Grand Imperial string res noise.

Postby pterm » 14 Sep 2017, 05:36

I had a closer look at the artifact at the timestamp suggested by Per, it looks like this in the waveform:
Image
This resembles a truncated "chirp" signal (although not exactly since it rides atop the played note):
Image from https://en.wikipedia.org/wiki/Chirp_spectrum#Deriving_a_Waveform_from_a_Target_Frequency_Spectrum
Our waveform image is 180 degrees different from the image from wikipedia, but that affects neither the sound nor the frequency content. This short chirp sounds like a click, so Clieto's description was spot-on.

As for the source, I have no idea.

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Re: Grand Imperial string res noise.

Postby cleito » 14 Sep 2017, 07:05

Nice.
I think the sample that nord uses is not just a sample but some other stuff that add up to make the sound. Maybe that's how they get a small file.
I made another post a few months ago about the royal grand 3d that have a strange thing too
https://www.norduserforum.com/post80728.html#p80728
Last edited by cleito on 14 Sep 2017, 07:13, edited 3 times in total.
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Re: Grand Imperial string res noise.

Postby maxpiano » 14 Sep 2017, 08:27

cleito wrote:Nice.
I think the sample that nord uses is not just a sample but some other stuff that add up to make the sound. Maybe that's how they get a small file.
I made another post a few months ago about the royal grand 3d that have a strange thing too
https://www.norduserforum.com/post80728.html#p80728


It is possible (I'd say likely) that the string resonance (sympathetic, not pedal down) is not sampled but calculated ;)
Maybe the algorithm they use has some little "singularities" on some notes/frequencies(?)
Last edited by maxpiano on 14 Sep 2017, 08:30, edited 3 times in total.
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Re: Grand Imperial string res noise.

Postby Mr_-G- » 14 Sep 2017, 09:08

I still do not hear it. :( I wonder: does it happen on a single note strike?
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Re: Grand Imperial string res noise.

Postby cleito » 14 Sep 2017, 14:25

Mr_-G- wrote:I still do not hear it. :( I wonder: does it happen on a single note strike?


Can you record the same notes C# and D from your piano and send the audio here?
Hit many times from very soft to hard and I will try to get your sound into the daw and see if it happens.
I suggest someone else record too, maybe is a problem with my keyboard.
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