Good SOS article on piano micing

I didn't read the article in its entirety, but noticed that in a few places they seem to concentrate on mic placement referenced to the strings, which may be misleading.

My pianist/rebuilder friend and I have discussed the relative importance of string sound versus soundboard sound, and we believe that string sound is relatively minor compared to the sound from the soundboard (however, refer to second paragraph below).

A interesting demonstration is to compare the sound of a solid body guitar with the power off to that of an acoustic guitar - without a soundboard, the sound is very weak.  This might suggest that microphone placement should concentrate on the soundboard, not the strings.

To capture what the pianist hears, perhaps they should be concentrating on getting the sounds of the action too.  While the hammers obviously make a sound when they hit the strings, there is a "reverse sound" of the strings hitting the hammers.  While not very musical, it adds to the percussive sound of the acoustic piano (and is very short-lived).

There are obviously other non-musical percussive sounds generated by the action of an acoustic piano, and it might serve recording engineers well to better understand the physics of pianos.

Somewhat related, Bosendorfer claims that the rims of their pianos are made from finger jointed spruce to increase the resonance of the rim over the more standard multiple laminations of hardwood favoured by most piano builders.

Just my two cents worth.

Glenn

A few personal comments/opinions (that stand to be corrected/modified):

1.  The strings and soundboard are not very far apart (when I had a Yamaha G2, dusting the soundboard was very difficult as there wasn't more than an inch or so space between them).  If a mic was 12 inches from the strings, the difference in distance between SB and strings wouldn't be significant - the mic would primarily pick up the loudest of the two sounds - I'm sure that would be the soundboard (try the guitar analogy/test).

2.  Grand pianos have two bridges, one each for the two runs of strings; Steinway (and others) have a continuous connection between the two bridges which is to transmit vibrations from one set of strings via the SB to the other set.  This leads me to think that the bridge is very important, and that it is very effective in transmitting string vibrations to the SB.

3.  My friend and I did a (not scientific) test as to where the various frequencies emanate - we concluded that the commonly held belief that bass sounds come from the "left" side and higher frequency sounds from the "right" side of the piano is an illusion based on what we think should happen.

4.  While strike transients are localized at the hammers, sound travels much faster through steel/copper than it does through air so that in effect the sound is transmitted instantaneously to the bridge(s).

5.  Since the sound we hear is simply pressure pulses in the air, and these pulses are transmitted to the air by the vibrating strings and soundboard, wouldn't the very much larger soundboard transmit far more energy to the air than would a very narrow string?  Isn't this why a solid body guitar has no volume?  The strings simply can't transmit much energy to the air - it is the soundboard that does the trick.

6.  The piano and the guitar are very similar from an acoustic point of view; both have strings that are struck, and which cross over a bridge at or near one end which is located directly on the soundboard.

7.  It is really worth doing the solid body/acoustic guitar test to see how minimal the direct sound from the strings is.  A solid body guitar can barely be heard at 30 feet - a good acoustic guitar can be heard in a small to medium auditorium without amplification.  The soundboard is everything in guitars, and I see no reason that the piano would be strikingly different in this respect.

8.  One other thought:  since we do play by ear (only tone deaf pianists don't and I don't know any), and in doing so, our attack and touch are very much influenced by the sound we hear (direct feedback is how we judge the sound while playing and how we play the next notes), shouldn't the microphones be placed at each side of our head near our ears?  While I say this somewhat in jest, there is merit in this approach.  But of course, the pianist also hears the sound that is dispersed throughout the room in which the piano is located - so room acoustics become very important.

I'm half expecting for someone from Moddart to add some learned comments about the relative importance of strings and soundboard.

Glenn

Some interesting reading:
http://www.pianobuilders.com/soundboards.html

Jake:

I think the article is excellent - certainly the best one I have seen.  The articles in SOS are probably some of the best in the business.  My only quibble is the constant reference to the strings.  I would use the word soundboard.  I quote a few passages directly from the article:

Again, the high frequencies from the strings like to travel in straight lines, so putting your mic high enough for it to 'see' the strings over the edge of the piano's case will help get you the brightest sound.

Most of the information I've found on close-miking grand pianos deals with positioning mics inside them, somewhere over the strings.

Al Schmitt, for example, talks in Behind The Glass of setting up his pair of Neumann M149 omni mics in this way "usually a couple of feet off the high end and a couple of feet off the low end, kind of at 45 degrees to each other". He also adds, in another interview, that he tries to aim the mics at the hammers to get sufficient attack in the sound.

I came across another interesting technique courtesy of an engineer called Cookie Marenco, who uses a near-coincident rig in the middle of the piano, taking advantage of the directional characteristics of two cardioid mics to pick out the low and high strings respectively.

There is some disagreement amongst different authorities as to how high the mics should be within the piano, with some engineers (often in pop, blues, or rock styles) preferring a closer position, where each string is more distinct, and others (such as Al Schmitt) favouring a more distant placement where the harmonics of the different strings have more chance to blend. The more distant placement has the practical advantage that it keeps the levels of the notes in different registers sounding more even — a mic placed very close in will pick up the strings next to it much more strongly than it will the strings further away.

One final quote from the article (which makes a good point):
When we interviewed Gus Dudgeon in July 2001, the legendary producer of Elton John remarked: "I never close the lid on a piano. It's the worst thing you can possibly do. Taking the lid off is even better, if you can get the lid physically off. The lid is only there to bounce the sound out into the hall when you're playing live with an orchestra."

But I always thought that the lid was to keep the dust off the workings.

This link is interesting: 
http://vanadium.rollins.edu/~tmoore/pia...dboard.htm

The writer has done quite a bit of research, and his article is available for members of the Acoustical Society of America (March 2006):
http://asa.aip.org/