Some things to think about when choosing mics.

[littledog]

Bottom line: go with what works/if it ain't broke... etc. Glad you're getting good results.

Sounds like you've got a real nice instrument there. I'm sure it's a real calling card for your studio. I know that is probably the deciding factor in 50% of the projects come to me. I even get a lot of work from people who do all their tracks elsewhere, but then need to overdub a "real" piano. Sometimes, once they are here, they even decide to stay and mix.

If you're determined to find small dia. mics that work, as i said before, try omnis. Lid off is not a bad idea either - you may be getting strange phase cancellations from the reflections.

Good luck!

[darrin_h2000]

You should try a couple of PZMs taped to a semi closed blanketed lid.

[Sennheiser]

Nice piano.

[littledog]

Originally posted by participant
And yes, this post by littledog makes him the force of nature that he is


Chad

I believe, for the sake of accuracy, that it should read "FARCE of nature"...

[littledog]

Originally posted by darrin_h2000
You should try a couple of PZMs taped to a semi closed blanketed lid.

... but ONLY if you really need the isolation. Or like that particular idiosyncratic sound for a given musical context. (Can you imagine recording Horowitz that way???)

[Harvey Gerst]

Originally posted by Michael Jones Thanks Harvey.
Could you (or anyone else) explain this: It seems to me that the small dia. condensor mics I have used on my grand piano, seem to lose definition in the A2 - A3 octave. Why is that?

Without actually hearing the problem live, I can't really venture much of a guess. My first thoughts are that the better off-axis response of the smaller diameter mics are picking up some kind of phase anomoly in the piano which isn't being heard by the LD mics, with their poorer off-axis response.

It might also be that the distance between the two mics is creating some phase cancellations in that range; try changing the distance between the two mics and see if the problem gets worse, get's better, or does the affected range move up or down slightly? Try the same thing with the mic height; does the sound in that range get better, worse, or does the problem range move up or down in frequency?

It may be as simple as a small standing wave inside the piano, which the small diameter mics are reacting to more than the LD mics. The small diameter mics may actually be giving you a more accurate picture of what's happening inside the piano at that exact miking position.

[Harvey Gerst]

Michael,

A few additional points to ponder:

The wavelength is 10 feet for an A2 note while the wavelength for A3 is around 5 feet. That means you may get some cancellations in the A2 to A3 frequency range if the mics are 2 1/2 to 5 feet apart.

Do those distances correspond to your mic placements on the piano?

[littledog]

My initial thoughts parallelled yours, Harvey, but earlier in the thread he said that he tried a wide variety of mic placements without being able to eliminate the phenomenon.

[Harvey Gerst]

Yeah, I saw that too, but when dealing with problems like these, the trick is to move things around and listen to what changes. Does changing the height (or distance) between the mics change the affected range? Does changing the height of the piano lid change the affected range?

It's pretty much trial and error till you can do something to affect the problem, and then analyse what you did to try and figure out what's causing the problem in the first place.

If moving the mics wider and nearer doesn't create any change, then it's not the horizontal position of the mics that are causing the problem.

If moving the mics up and down doesn't create any change, then it's not the vertical placement of the mics that are causing the problem.

If moving the piano lid up and down doesn't create any change, then it's not a piano lid standing wave that is causing the problem.

That leaves the possiblity of a standing wave inside the piano (try some padding on one inside wall to see if it "changes" the problem), or the mics simply have a dip in that range, or an impedance mismatch with the preamps, or any number of other possibilities that need to be eliminated, one at a time till you arrive at a solution.

It may even be that the "problem" doesn't even exist; the piano may actually have a loss in response between A2 and A3, and the LD mic's greater proximity effect is filling in this void.

[Michael Jones]

Wow! Harvey, Little Dog, you guys have given me some great information, and some good points to ponder.
More experimentation is definately needed!

In this room, when I'm just playing the piano, it has a wonderfully soft, warm tone to it. I think that's pretty typical of Boston pianos, unlike say a Yamaha C7 which has a decidedly bright tone.

It's that soft, warm tone I'm trying to capture, and I know the piano is capable of delivering it in that room. The "attack" walls of the piano are acoustically treated with absorbers and diffusers, so I don't think I'm getting any phase anomilies from that.

I usually mic it with the lid in the full up position, lowering the lid to the "short stick" seems to make it worse.

Harvey- I'm constantly amazed at your ability to visualize what's happening, and offer suggestions for improvement. When using the SD's they seem to benefit by allowing a little more air or distance from the source, so I have one mic located about 12"-15" above the harp on the treble side; in keeping with the 3:1 rule, the other mic would then be placed approx. 4' - 5' from the first mic on the bass side, and approx 18" above the harp; in effect placing it at the 1/2 wave length of A2! (Doh!)
With a little more judicial placement, the effect is lessened, but not completely resolved, and the problem does indeed seem to shift in frequency. Does this mean though, that by moving the mics around, I'll just be chasing wave lengths around, in effect trading one wave length's phase cancellation for another? Or, can I phase reverse at the mic pre and resolve it? I guess I'll just have to try it.

I have several mics I want to become proficient with on this piano, because, as you said, different keys can pose different problems for a given mic.

I think I have the TLM's down pretty pat on it and seem to work best in the key of Eb maj. but don't sound quite as nice on something like Dmaj. The SM81's sound VERY musical in this key, except for the afore mentioned problems. (Just to give you an idea of where I'm comming from.)

I still have the RCA 77DX and have only just begun to work with it. You kind of scared me initially, so I make sure that I move VERY slowly with it, and work gingerly around it. But the initial results I have had with it are astonishing!

Thak you so much for taking the time to educate me in this matter.
~Michael~