"Room Tuned to the Key of G" experience

Lee Barker · #1 11-03-2009, 10:56 AM

Somewhere on TB, probably this forum, I learned that when you have that roaring sound on a certain note, move your amp.

We were playing a medium sized convention breakout room, full of chattering networkers on wine and crumbly crackers supporting bland cheese, and when we (two guitars, bass, singer) landed on a G it was like being close to a Titan V beginning its journey to shed the gravitational force of Florida.

I moved my amp--Markbass 112 combo--back a foot and voila, we were as neutral as Switzerland.

I tried to find the original thread where I learned this but couldn't unearth it.

Perhaps this experience will be of some value to someone else.

RustyAxe · #2 11-03-2009, 02:13 PM

Yeah, good post. I regularly play a room that gets VERY boomy on D and E ... I just move my amp and it's better.

phxlbrmpf · #3 11-03-2009, 05:28 PM

When I was doing some recording in our rehearsal space the other day, our drummer's kit always rattled when I played the lowest 2 G notes on my bass. When I played the G on the 12th fret of the G string or the high G on the 24th fret, it didn't respond, though. Can someone explain the physics behind this to me? I thought rooms responded to a certain frequency but don't the low G and the G one octave up have different frequencies?

JustDavid · #4 11-03-2009, 08:08 PM

Harmonics. Briefly, lower notes also 'include' a portion of the upper notes. Your "E3" G 'includes' your open G but the open G doesn't 'include' the lower G.

MNAirHead · #5 11-04-2009, 12:47 PM

Quote:

Originally Posted by JustDavid

Harmonics. Briefly, lower notes also 'include' a portion of the upper notes. Your "E3" G 'includes' your open G but the open G doesn't 'include' the lower G.

Wow great susinct answer to an indepth topic

phxlbrmpf · #6 11-04-2009, 02:01 PM

Yeah, makes a lot of sense to me. Thanks!

SteveC · #7 11-04-2009, 02:03 PM

Quote:

Originally Posted by JustDavid

Harmonics. Briefly, lower notes also 'include' a portion of the upper notes. Your "E3" G 'includes' your open G but the open G doesn't 'include' the lower G.

Nice work.

jaywa · #8 11-04-2009, 05:49 PM

1) Rolling some low-end off your amp helps as well (as long as you're still getting solid P.A. support).

2) So does getting the amp off the floor.

I used to have this problem a LOT (though for me the problem notes were usually low F or F#), and once I started doing the above two things routinely, everything cleared up.

MarkTAW · #9 11-04-2009, 07:57 PM

Quote:

Originally Posted by phxlbrmpf

When I was doing some recording in our rehearsal space the other day, our drummer's kit always rattled when I played the lowest 2 G notes on my bass. When I played the G on the 12th fret of the G string or the high G on the 24th fret, it didn't respond, though. Can someone explain the physics behind this to me? I thought rooms responded to a certain frequency but don't the low G and the G one octave up have different frequencies?

The drummer's kit only responds to lower frequencies.

A sound wave is literally a wave - it's a wave in the air that travels at the speed of sound, just like when you go to the beach you see waves that are in water and travel considerably slower.

A low G is 49 hz. The wave is 23 feet long. The second one up is at 98 hz, the wave is 11.5 feet long. The next octave (12th fret G string) is 196 hz and just 5.7 feet long, and the next octave (24th fret) is 392 hz and just 2.9 feet long.

Now imagine you're at the beach - which wave is going to lift you up off your feet?

Now the drums, or their location in the room, or some other aspect of the drums sets them up perfectly to catch one of those waves.

That's why it rattles for the lower notes & not the higher notes.

TimmyP · #10 11-04-2009, 10:47 PM

Rooms have "hot spot's that are based on the room dimensions. These are many and complex, but here's some of the basics: http://www.padrick.net/LiveSound/CancellationMode.htm

MarkTAW · #11 11-04-2009, 11:27 PM

You can calculate them on this website of this guy I totally don't know.

http://www.marktaw.com/recording/Aco...WaveCalcu.html

TimmyP · #12 11-05-2009, 12:20 AM

Quote:

Originally Posted by MarkTAW

You can calculate them on this website of this guy I totally don't know.

http://www.marktaw.com/recording/Aco...WaveCalcu.html

Cool app. There's also a nice download on that page.

MarkTAW · #13 11-05-2009, 12:30 AM

Yeah, Ethan Winer (who makes the DOS utility) is a good guy, makes some good, relatively inexpensive bass traps (which are used to tame this exact problem).