Microphone for Grand Piano Recording

Discussion in 'Acoustic Keyboards' started by bf2008, Apr 12, 2009.

  1. OE1FEU

    OE1FEU Active Member

    Joined:
    Aug 27, 2018
    Location:
    Vienna
    As to the first part, can you be a little more specific as to how you would actually go about recording pink noise? From what source etc., please?

    I feel that the OKM, due to its tiny membrane already comes into saturation. While I usually use the OKMs for concert recordings and have them as boundary mics worn over the lapels of a jacket, in the recording presented here I wore them in-ear, as intended, so very close to the piano itself. So let's try to focus on the Rødes because I don't expect to use the OKMs for anything but recital bootlegs.

    As to the piano: No offense taken, quite on the contrary. As you can hear, I am not a 'real' pianist, but I have worked with quite a number of professional and renowned pianists as artist manager and had the privilege of speaking often and intensely about piano playing. Also, in the past couple of months I took a really deep dive into understanding piano technology, inspired by the movie "Pianomania", whose protagonist is considered the guru of all piano technician gurus. He was the one to appraise the piano and together with him I made a plan how to get the best out of the piano. In short: I have had the action completely reworked with new repetition levers, back checks. Also the piano has new hammers, original Steinway ones and they have been minimally adapted to fit the older parts of the action. Also, the strike line for the upper registers has completely been reworked, i.e. the hammer heads were removed and their position adapted to the best sound possible on the hammer shanks. The sound board has seen significant repairs over the years, but by now it is in a good equilibrium and I can honestly say that this piano has more power and sustain than any modern B I have played. The wood of the soundboard is still the original Appalachian fir, which is by many considered vastly superior to today's Alaskan Sitka wood.

    Altogether the piano has been regulated and tuned by real experts and I am confident that the dynamic range is really huge, both in ultra-pianissimo and fortissimi. And while it is a really loud beast, I can't get it into saturation, the limit being my own playing. I believe that a real Russian pianist or a marvel like Frederic Rzewski could squeeze another 3 dB out of it before actually hitting saturation.

    By now you may understand why I am so frustrated at the limited dynamic range of the recordings.

    For more details on the piano I have documented its arrival, appraisal and repair in a German piano forum:
    https://www.clavio.de/threads/steinway-b-seriennummer-60103-1887.23873/
     
  2. paulears

    paulears Well-Known Member

    Joined:
    Feb 7, 2014
    Location:
    Lowestoft - UK
    Home Page:
    Things like the usual editors - SoundForge, audition etc have a generator built in - but in the absence - record the hiss between FM radio stations - it will do for this. Whatever you use to edit/record on should let you create the test recording. I think that with the specialist work on the instrument you can rule that out then - I was thinking the opposite, maybe a worn out but nice sounding beast!

    If it can produce this range it should be perfectly possible to record it. The files you have are flacs, capable of really good quality - but what format did you record to? wav? Was there a file conversion that has gone wrong somehow? If one of them has more bit depth, and has been reduced to fit the other? To be honest, that's a total guess because my understanding is that with floating point, this doesn't happen - but maybe there is a setting that is doing the conversion - badly? Those OKMs I'm not really sure of. My experiments years before with binaural were not the best. I had a dummy head which was OK, but really needed headphone to make the stereo sound field work. On speakers it was pretty odd. Another test would be to try to record a continuous tone that started inaudible and increased at a steady rate - with one microphone left and another right, and see on a stereo side by side meter the two levels rising - they should track together. If one is performing badly against the other it should be obvious.

    Going back to the OKMs - be aware that the lapels of a jacket are nowhere near going to work as a boundary, as in an infinite plane that has the microphone as part of it. If the mics are more than a few mm away from the surface, they operate in a non-boundary mode, and of course, fabric is a great absorber of high frequencies. You also cannot move because you rotate the stereo field. I strongly recommend that you fix the mic position. The actual technique should reflect the sound you want. A semi-distant position with either Blumlein fig-8 or XY generally works best in nice sounding rooms, but in a troublesome or less, er, pleasant sounding room, a cheat with close mics, positioned by experimentation with the piano in question and then balanced and blended with some good quality reverb plug-ins may well be the best. My colleague's C3 records best close miked simply because like yours, his room has hard surfaces - his with carpet, but still not nice sounding. We record his piano close in - and use a rather quaint digital Yamaha reverb unit from the 80s - their very first attempt at acoustical modelling, and in this case, we use the one excellent programme - Munich Cathedral, which blended in low sounds great.

    If you oversaturate a microphone, overload it, if you will - the resultant sound is just rough. There is non-linearity when the levels go up to close to maximum, but this can easily be tested as the culprit by recording from an increased distance - in verse square law works for you so a doubling of the distance has a much bigger impact on record levels. Of course the room content increases, but it will let you test dynamic range.
     
  3. OE1FEU

    OE1FEU Active Member

    Joined:
    Aug 27, 2018
    Location:
    Vienna
    Her is something additional that might actually help:

    Internals.jpg

    So, this is a recording I've made with the internal microphones of the Tascam DR44-WL. Hopefully you can deduce some more information from this recording. Instead of finishing just with the chord, I've left it dangling for quite a while, which also made me realize that more than a minute of sustain is quite something for an instrument of that age.

    https://drive.google.com/open?id=1mBfLncvsKraWwX6608Jj_ndsBjm2D66C

    The recordings with the DR44-WL are all 16Bit at 44.1kHz. Conversion to flac via Linux command line with highest possible compression ratio; the original .wav is 21MB, the resulting .flac is 4.5MB.

    The OKMs have a very specific use case for me and as such they have been of incredible service for more than 30(!) years. Taping classical piano recitals is something you don't want to do with visible gear, so back in the 80s together with a WM-D3 this was precisely what I needed. The resulting recordings by now have kind of a historical dimension; I taped pianists like Horowitz, Richter, Arrau, Michelangeli and in some cases the recordings are the only existing ones, such as this one from 1987:



    When placed carefully, they reproduce a really superb piano sound, such as in this case with Russian pianist Igor Zhukov and a piano prepared by one of the best technicians in the world: https://drive.google.com/open?id=1heKuLniowM21wIMoNGXCSpOY81OhqTDU

    Recording is from 1996 with the OKMs and a Sony DAT TCD-D8. Please enjoy, it's gorgeous.
     
  4. paulears

    paulears Well-Known Member

    Joined:
    Feb 7, 2014
    Location:
    Lowestoft - UK
    Home Page:
    I've taken the tracks to my studio and while I'm not sure what the result actually mean, there are a few things that stand out that might be indicative of a problem your end.

    The recording of the recital with the applause at the end first. Your old standard to perhaps use as a guide?

    I tried listening in both Sound Forge and Cubase, to get access to different tools. The recital recording has a very solid stereo image that follows the pianist quite closely, and it is balanced to the centre, which I always think is the aim - centre keyboard = centre of the image. The pianist's perspective, which is of course wrecked for the audience, who don't get this with the usual piano placement. This recording has a swing about the centre, and the field when viewed looks quite typical. I'm never sure what is wrong with some I see, but usually something in the sound leads me to the stereoscope meters. The dynamics are also quite pronounced, but in a realistic manner. The unwanted mechanical noises are absent to the best of my ability to detect them.

    In your OKM recording, there are what sound like 'cuff-link' noises, fabric noises (I think - a sort of swish) and the stereo image is all over the place. This doesn't make itself very obvious in the recording, but I close my eyes and can detect shifts in the stereo image, so I look on the meter and it's visible - and in this case, there is a favouring of the lower part of the keyboard. I still like this recording technique the least.

    The Omni more closely reflects the type of sound in the recital recording - which interestingly I did not detect the audience until they clapped!

    Your new recording with the sustained end note shows that there is dynamic range capability. It also reveals some technical issues I think. The sustained note would normally be specially static. The instrument just decays. Obviously, the length of the strings determines that some will decay more quickly - but the image should stay fixed, perhaps with some tiny room anomalies in a space with large RT60 value, but you have a small space, so I expected stability. The recording shows the left and right decay varies - the meters fluttering and the stereoscope moving, which is odd. As if the two channels are not tracking together?

    The one thing you may have not noticed is that there is virtually nothing above 10K in ANY of the recordings. In fact, the energy is mostly below 4-5K, and tails off rapidly above this. A gentle slope downwards from just over 4K, with it almost gone by 6-7K, and missing above that. I changed the scale to check, and it's below the level my meters can show. The fact that the old recording and the new ones both have this suggests something other than your limited dynamics. The recorder and it's internal microphones often are commented on for being a bit bright - in your case, there is no HF response? Something is adrift here. Can you check this? Do you have any other recording device to use as comparison? Even an iPhone maybe? Something you can use to analyse what is going on? Could you record that piano decay on two devices - recorder and phone, sync them up and route to L and R and then see how the decay and frequency response differs. The sustain recording shows that the piano has a greater dynamic range than you thought perhaps, and you successfully captured it, even though the noise floor was evident. This didn't seem to decay 'weirdly', but was quite natural apart from the left/right flutter. Why was the original recording lacking dynamics that were recorded later? I'm left wondering if you just overplayed the quieter passages and ran out of steam? Seems unlikely, but the decay recording rather removes the piano and recording device from any blame of not being able to cope with dynamics, which only leaves the player. Could this have anything to do with the loss of the HF end? As you play louder, I assume the piano produces more overtones, so if the recorder/microphone system does not capture it, maybe this is what makes you hear it as lack of dynamics? Maybe?
     

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