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"Interference" from nearby instruments?

I've recorded a large piano recital the last few years that invariably has two grand pianos on stage placed end to end (i.e. so the musicians can look at each other). The lids are up, so the right piano is aiming AWAY from the audience. Certainly not ideal, but I haven't convinced them to do it any other way.

There are also other instrumental pieces sprinkled through the recital, so off to the side (maybe 20 feet?) will be sitting several cellos in open cases, a harp, etc.

What I've noticed is that on pieces with one piano being used where it is being played very loudly, I am hearing something that sounds slightly dissonant in the recording. It's only on the loudest passages, and I'm having trouble putting my finger on what it is. It certainly doesn't sound like clipping. It's possible it's there with two pianos as well, it may be harder to hear it with the extra sound from the second piano.

Could I be hearing the string instruments sympathetically singing from the loud piano? The second (unused) piano? That seems less likely since it would be damped. Are harps damped like a piano when not being played? My guess would be the cellos, but I thought I'd throw this out to see if others had run into this and what you did about it.



BobRogers Thu, 02/19/2009 - 16:48
Welcome to Physics 101. I don't have a particular guess as to what is vibrating, but this is a constant fact of life in recording. People seem to filter these things out during a live performance, but they stick out when listening to a recording. Listen close. Use your ears. Tell people to move things around. Put things in cases. Blankets, foam, and gaffer tape can be a help. Try to make the live performance as clean as possible before you start moving the mics around.

Once you have the purest performance possible it's time to set the mic. I'm of the philosophy that you shouldn't let trying to hide the worst parts of the performance (e.g. noise) get in the way of recording the best parts of hte performance. Do the best you can at making the environment as good as possible and then try to get as much music on disk as possible.

In the end it may be something out of your control - a piano that needs to be rebuilt for instance. In the end, the job at an acoustic recording is to produce a (reasonably enhanced) reproduction of the performance, the instrument, and the room.

Codemonkey Thu, 02/19/2009 - 18:54
BobRogers wrote: In the end, the job at an acoustic recording is to produce a (reasonably enhanced) reproduction of the performance, the instrument, and the room.

So what you suggest is that acoustic recording is meant to produce the most true to life reproduction of the performance and make it available for everyone - since not everyone can sit in the sweet spot?

Logically, recording a rock band is almost the same - except there's more fabrication of the sweet spot, more electronics and more sacrifices to be made.

I'd like to add that in our church, the snare rattles a lot when the piano is being played. When the drummer is present, the drums are typically being played so it's nigh impossible to notice.

soapfloats Thu, 02/19/2009 - 21:38
Sympathetic vibrations can be a pain.

In my former band, the drummer's snare literally sang when I hit a G.
Buzz, rattle, sizzle.
I took it to mean that he properly tuned his drums, and dealt w/ it. It was also live.

In the church I record in, the owner has cymbals, snares, kicks, hand drums, and hand percussion galore.
I move everything as far as possible and also dampen it w/ sheets/blankets, etc. Anything to limit its vibrations.

But like Bob said, when you enter the world of recording (acoustics, electronics, physics, psychology, and more!), there's a lot of variables.

It could be something completely out of your control.
If you've taken care of everything you *can* control, you've done your job.

BobRogers Fri, 02/20/2009 - 05:36
Codemonkey wrote: [quote=BobRogers]In the end, the job at an acoustic recording is to produce a (reasonably enhanced) reproduction of the performance, the instrument, and the room.
So what you suggest is that acoustic recording is meant to produce the most true to life reproduction of the performance and make it available for everyone - since not everyone can sit in the sweet spot?... I guess that's an overstatement on my part, but at the very least, the most common aesthetic choice in acoustic music is to produce a recording that reproduces the experience of listening to a live performance. In classical music, there are plenty of people who will tel you that the naturalistic approach is "the right way to do it." I'm not in that camp. I prefer a naturalistic approach, but I recognize that it as a choice and I shouldn't have called it "the job."

I'll just note that in pop music it is common to go in the opposite direction and provide live sound support that mimics a studio-produced recording. (For example, individually micing the drums and panning them across the stereo field to create a "50 foot drum set.) I'm pretty much a naturalist in my pop recordings as well. I try to position instruments in the stereo field as I imagine them on stage and avoid emphasizing things like widely panned stereo guitar effects. But in this case I'm sort of going against the trend.

BobRogers Fri, 02/20/2009 - 09:02
Sorry to be unclear. It's my personal preference for a style, but I'm not going to tell someone that their recording is not legit if they try something else. I thought that my original post came off as implying that "my way is the only way" and I wanted to correct that.

It's like the distinction between people who feel that an electronic drums are not really drums and those who simply prefer acoustic drums to electronic.

Cucco Fri, 02/20/2009 - 11:04
I understand exactly what Bob's trying to say and I'm probably in a very similar if not the same camp.

When recording an acoustic performance (for lack of better terms, we'll say a "classical" performance - although I believe it applies nearly universally to all "classical" genres as well as jazz), the goal is not to significantly alter the sound of the natural performance. To some, this means that there can not and should not be anymore than 2 mics (since we have 2 ears and because multiple mics = phasing issues). Some take it to the extreme that those two mics must be coincident pairs (again, phasing).

My take on it is, again, don't make the instruments or the hall or any other aspect sound unnatural, but to at least utilize the equipment I have and it's respective strengths to enhance the perception of the recording itself. That's to say, I may add reverb or put up a few mics to capture natural ambience. I may place a spot mic on soloists. I'll also HPF out rumble where appropriate and even........use an EQ (gasp!!). All of these things are considered no-no's to the purists, however, do not (IMO) alter the intent or nature of the performance itself.

In my opinion, there are so many correlations between recording and cooking as well as recording and photography. In the cooking example, a true purist would take a quality piece of meat or fish, sear it to the proper temperature and eat it. On the other hand, I don't know of a single professional chef who wouldn't season that meat with some kosher salt and often fresh-cracked black pepper at a minimum. One is purity, the other is a suitable and widely acceptable enhancement.

All of this being said -

Yes, the adjacent (damped) piano will still ring - loudly if excited. (Bear in mind, the entire length of the string isn't damped, there's still plenty of vibrating surface to excite.) I've played in many a room where every note I play on my horn vapidly excites the piano(s) in the room.

As for the snare drum one knows of that problem more than a horn player! We are constantly in search and destroy mode for those cursed things! I can't stand it when I'm playing in an orchestral situation and we've just gotten done doing some Tchaikovsky piece with a full snare battery and then we go into Brahms 3 and the percussionists forgot to disable the snares! Every time the horns play, there's a nice drum roll effect in the background.

That said, I've done numerous recordings where we'll retake certain sections because the snares are going crazy but they'd be too distracting to disengage/re-engage during the performance or main recording session. Nothing's worse than a Mahler 3 recording where you hear a beautiful, loud ending of the first movement only followed by "THWAP" of the snares disengaging for the second movement...


anonymous Fri, 02/20/2009 - 11:35
Thanks for all the replies...

It sounds like I need to request that the second piano have its lid lowered when it's not being used. That should help.

I'm not sure what to think about the harp sitting stage left of the pianos though - no damping available there as far as I know, and no lid. Throw a blanket over it during the other pieces? (Just kidding)

It may turn out that the second piano is the biggest issue. I'll go back to the recordings and see if it seems the problem is more pronounced in one channel than the other, may be able to get an idea for which direction it's coming from.



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