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Guess How Big My Speakers Are

If you read any of my threads on here or looked at my virtual system you probably already know the answer to this question, but for those who have not, try this as a thought exercise. Given this plot alone how big a speaker do you think this is?

Frequency response plot showint extension to 20 Hz

 

Hints:

  • 2’ from sides, 1.5’ from rear
  • Ported
  • Not horns
  • No EQ applied. This is the natural in room response using short sine sweeps.
  • For a living room this is a well treated room with GIK soffit traps, bass traps and diffusion panels strategically placed.

I’ll reveal my answer if we get 5 guesses or more. :)

erik_squires
asvjerry's avatar
asvjerry
4,724 posts
 

@erik_squires , different mike places and volumes would be interesting in themselves, but the averages would be an education. ;)

Have a pleasant Xmas.

 

czarivey
5,946 posts
 

I guessed the closest. SF Grand Piano uses 6.5" woofs

herman
2,261 posts
 

it is impossible that you are actually getting as much output at 20Hz as you are in the midband.

@herman In an anechoic room you’d be correct. The room however bedevils those expectations, and that’s the point of the posting. 

I'm going to stick with my initial response. I don't care what kind of room you are in, .. you are not  really getting a strong 20 Hz out of those speakers

 

erik_squires OP
16,289 posts
 

@herman but it is, and I’ve measured it. It’s not "real." It’s not the capability of the speaker so much as the resonance of the room.

Rooms can add 20 dB or more in a node, so this is totally possible. However, it is very much range limited. :)

 

From my new blog entry, you can see that compression eventually must set in...

 

Here you can see the output at 60, 70 and 80 dB is fine, only when we get to 90 dB is the output compressed.

erik_squires OP
16,289 posts
 

@herman 

I did retest using Room EQ Wizard and OmniMic.  REW measures about 5 dB lower at 20 Hz than OmniMIc.  It also shows a weird clipping at the top octaves.

While I agree 100% that you can't get loud at 20 Hz with small drivers (this is pure physics) I hope you see that my argument that rooms are complicated and we can't assume we know what's going on without measurement is worthwhile. :)

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