Audacity Forum

Guitars are guitar-shaped to keep the resonances from all piling up in one place. If they were round, they would sound like playing into a rain barrel. But they are resonant cavities on purpose, so they are going to have oddities.

I wonder if that low note is the guitar body ringing end to end. There will be three peaks: the upper bulge, the lower bulge and the whole thing. I wonder how I would go about testing that.....

Koz

I thought I'd post a full length song before we reached post #200...

So here is something full-length... Not a very long piece though...

I did two takes on it... both far from perfect... and no editing at all...

On the first the mic was at about 35cm from 12th fret.
On the second I pushed the mic about 5cm back so it should be about 40cm from the guitar (because i have it a bit higher than the guitar the angle to the sound hole probably changed too and it should be more in line with the sound hole...). Also the preamp gain on the second take is slightly lower (I had lowered it before moving the mic, because I had a bit of clipping in other tune i played in the setup of the first take, so the lower volume of the second take is not only because the mic is more distant...)

http://www.gravato.eu/recordings/mi_favorita-take1.flac
http://www.gravato.eu/recordings/mi_favorita-take2.flac

On sound quality I think I prefer the first take.
On a side note... the weird sounds you might hear somewhere in the middle it's me trying to add some special sound effects with my mouth which recorded don't sound as good idea as it did when I was playing...

kozikowski wrote:Guitars are guitar-shaped to keep the resonances from all piling up in one place. If they were round, they would sound like playing into a rain barrel.

interesting
what about a banjo? different sound but not a rainbarrel imho.
at what point would the volume make it a helmholtz resonator and the wide hole simply tune it broadly to the guitar's range? or could that be done?

stevethefiddle wrote:

bgravato wrote:

kozikowski wrote:Something we have not looked at much, but since we're talking SNR, the volume level rises rapidly as the microphone approaches the sound source (inverse cube law isn't it?). With the microphone position we are looking for the "sweet spot" - the best balance between all relevant factors.

i thought it was 6db (square law) every time you doubled the mike distance. is it different when you get real close? or does noise low freq emphasis add in when real close to make it cube law?

I thought it was square law, too.

I did briefly consider a passive Helmholtz Resonator in the same room as the instrument tuned to the lower peak tone to keep the room and the instrument from resonating at the same place. If you did it just right, you could spend months moving the guitar, resonator, and microphone around and never have to actually play anything.

But then I had a good lie down with a cool towel on my face and the urge went away.

I considered shooting white noise into a quiet room and recording it and then place the instrument into the same room and repeat. Subtract the two sweeps and that should result in a reading of the resonances of the instrument.

Or not.

Koz

Banjo is not a resonant cavity. It's two soundboards closely coupled. If it does have a resonance, it's way up there and not likely to be musical.

Koz

whomper wrote:i thought it was 6db (square law) every time you doubled the mike distance

Put it in context mate:
"Something we have not looked at much, but since we're talking SNR, the volume level rises rapidly as the microphone approaches the sound source"
You get the general idea don't you?

stevethefiddle wrote: You get the general idea don't you?

of course
the question is whether as you approach the extreme point of closeness if the formulas and theory go bananas like a singularity in a black hole of quantum physics.

It just keeps going up, but the theatrical balance of the music goes crazy, plus, in a cardioid microphone, the proximity bass boost goes up. None of that sounds very good.

Koz

<<<On sound quality I think I prefer the first take.>>>

I think the second one sounds a bit more mellow and pleasant, but I think this went beyond my ability to improve it a long time ago.

Can you get to a larger hallway?

Koz