Michael R Price
Screenwriter
- Joined
- Jul 22, 2001
- Messages
- 1,591
I borrowed a SPL meter from a friend and measured the bass response from 25-200 Hz 1/3-octave, at my seating position in 3 configurations: 1) with only the left speaker, in its normal position; 2) with only the left speaker, sitting in and pointing towards my front left corner; and 3) with both speakers (mono) in their normal positions. Oddly enough, the response declined quickly below 200 Hz (20 dB or more by 25 Hz) whereas LspCAD predicted +/- 4 dB from 20 Hz up.
Here's the Excel graph:
Weird, eh?
I had been noticing a few things before the measurement:
- The bass sounded very natural and deep, but there was less of it than I was used to. I thought this was because the 281s deliver accurate and non-boomy bass. But it honestly didn't seem like 10-15 dB less than normal.
- Walking around the room created much more bass output but it sounded 'uneven' and boomy, like certain frequencies got exaggerated a lot more than others.
- Bass that was hair-raising and 'chairshaking' didn't seem as loud as the physical movement would indicate.
So I'm really not sure what is going on here, since even corner loaded there was a big decrease in output. I'm very hesitant to doubt the meter (RS analog, C weighting slow response, rolloff compensated).
The question is:
Are the speakers a problem? I have tried to seal off any air leaks (my construction on the 281s was not very good) but there may be a few minor ones still. (Would that cause such a dramatic loss of output?)
Is my seating position, and not speaker position, the problem? I think so, because the results from corner loading were similar to the others. But I'm not sure how one particular spot in the room can just cancel out everything like that.
What else? I felt like I was getting really great bass out of these things but now it seems as if I'm *seriously* missing something.
The speakers face down the long way of my 15x11x8 room, 4 feet from the back wall and 2 from the sides. I sit between the speakers 7 feet from them and 4 feet from the back wall...
Is there any way to calculate the room response based on a position in a room? I've heard about dividing room dimensions into 565 to get node frequencies... but this seems like a bigger problem. I'm quite confused. :frowning:
Thanks for the help, guys. I greatly appreciate it.
Here's the Excel graph:
Weird, eh?
I had been noticing a few things before the measurement:
- The bass sounded very natural and deep, but there was less of it than I was used to. I thought this was because the 281s deliver accurate and non-boomy bass. But it honestly didn't seem like 10-15 dB less than normal.
- Walking around the room created much more bass output but it sounded 'uneven' and boomy, like certain frequencies got exaggerated a lot more than others.
- Bass that was hair-raising and 'chairshaking' didn't seem as loud as the physical movement would indicate.
So I'm really not sure what is going on here, since even corner loaded there was a big decrease in output. I'm very hesitant to doubt the meter (RS analog, C weighting slow response, rolloff compensated).
The question is:
Are the speakers a problem? I have tried to seal off any air leaks (my construction on the 281s was not very good) but there may be a few minor ones still. (Would that cause such a dramatic loss of output?)
Is my seating position, and not speaker position, the problem? I think so, because the results from corner loading were similar to the others. But I'm not sure how one particular spot in the room can just cancel out everything like that.
What else? I felt like I was getting really great bass out of these things but now it seems as if I'm *seriously* missing something.
The speakers face down the long way of my 15x11x8 room, 4 feet from the back wall and 2 from the sides. I sit between the speakers 7 feet from them and 4 feet from the back wall...
Is there any way to calculate the room response based on a position in a room? I've heard about dividing room dimensions into 565 to get node frequencies... but this seems like a bigger problem. I'm quite confused. :frowning:
Thanks for the help, guys. I greatly appreciate it.