I Think I Understand Baffle Step...Plz Confirm

69stingray · 4th December 2006, 11:57 PM

So.....generically speaking, when the wavelength produced by the speaker is the size of the cabinet, it reflects off the cabinet, giving you approx. 6 dB more SPL....that I understand.

For the longest time I could not understand why it is a "loss" of bass and not a gain in "midrange/treble".

I think I know why, please confirm.

When a speaker is rated at say 87 dB, that is as measured on a large baffle, which means with the +6 db baffle step. So when that 87 dB speaker is used on a narrow cabinet (narrower then the test baffle), you get a ~6 dB loss in SPL, correct????

Tenson · 5th December 2006, 12:22 AM

It is in fact a gain in midrange and treble, but since everyone uses speakers mounted on some kind of baffle or another (the driver itself acts as a baffle to frequencies that ‘small’ relative to it), it is taken into account in the efficiency rating, yes. So relatively speaking you get a bass drop.

Also, baffle step is not generally considered to be when the wavelength is bigger or smaller than the baffle, but usually done by the half wavelength. So if the half wavelength is bigger than the baffle you get the drop in bass.

At least I hope that is right

Timn8ter · 5th December 2006, 02:05 AM

http://www.trueaudio.com/st_diff1.htm

hongrn · 5th December 2006, 02:23 AM

Here's a real simple explanation:

http://www.geocities.com/cc00541/index.html

Hong

Tenson · 5th December 2006, 03:18 AM

No kidding!

hongrn · 5th December 2006, 04:00 AM

Tenson,

Try it again before posting.

Svante · 5th December 2006, 06:59 AM

This is just a semantic problem. There are two ways of looking at it.

1. If the driver is thought of as playing in full space at low frequencies, there will be a gain of 6 dB at high frequencies compared to the level at low frequencies due to the baffle step.

2. If the driver first is mounted in an infinitely large baffle, there will be a 6 dB gain over the entire frequency range. If the baffle then is narrowed to the size of an ordinary loudspeaker, there is a loss of 6 dB at low frequencies.

Once both points are understood, it becomes unimportant which explanation model you choose, since they are equivalent (sort of).

sreten · 5th December 2006, 09:32 AM

Quote:

Originally posted by 69stingray

I think I know why, please confirm.

When a speaker is rated at say 87 dB, that is as measured on a large baffle, which means with the +6 db baffle step. So when that 87 dB speaker is used on a narrow cabinet (narrower then the test baffle), you get a ~6 dB loss in SPL, correct????

Hi,

Yes you are correct. Drivers are measured with pi loading.
Boxes have 2pi loading in the bass, going up to pi in the midrange.
So compared to measured pi response, boxes are -6dB in the bass.

/sreten.

Pano · 5th December 2006, 10:35 AM

Hey Tenson,
Good to see another Opera Browser user on the forum!

Link is working now.

Tenson · 5th December 2006, 02:44 PM

I'm afraid the page still doesn't work for me, but never mind.

4th December 2006, 11:57 PM	#1
69stingray diyAudio Member Join Date: Apr 2005 Location: NH	I Think I Understand Baffle Step...Plz Confirm So.....generically speaking, when the wavelength produced by the speaker is the size of the cabinet, it reflects off the cabinet, giving you approx. 6 dB more SPL....that I understand. For the longest time I could not understand why it is a "loss" of bass and not a gain in "midrange/treble". I think I know why, please confirm. When a speaker is rated at say 87 dB, that is as measured on a large baffle, which means with the +6 db baffle step. So when that 87 dB speaker is used on a narrow cabinet (narrower then the test baffle), you get a ~6 dB loss in SPL, correct???? __________________ Audio DIY Page FOLLOWMY529.COM - Subscribe and follow the performance of my daughter's 529 College Saving Account.

5th December 2006, 06:59 AM	#7
Svante diyAudio Member Join Date: Feb 2004 Location: Stockholm	This is just a semantic problem. There are two ways of looking at it. 1. If the driver is thought of as playing in full space at low frequencies, there will be a gain of 6 dB at high frequencies compared to the level at low frequencies due to the baffle step. 2. If the driver first is mounted in an infinitely large baffle, there will be a 6 dB gain over the entire frequency range. If the baffle then is narrowed to the size of an ordinary loudspeaker, there is a loss of 6 dB at low frequencies. Once both points are understood, it becomes unimportant which explanation model you choose, since they are equivalent (sort of). __________________ Simulate loudspeakers: Basta! Simulate the baffle step: The Edge

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5th December 2006, 12:22 AM	#2
Tenson diyAudio Member Join Date: Feb 2006 Location: Kent	It is in fact a gain in midrange and treble, but since everyone uses speakers mounted on some kind of baffle or another (the driver itself acts as a baffle to frequencies that ‘small’ relative to it), it is taken into account in the efficiency rating, yes. So relatively speaking you get a bass drop. Also, baffle step is not generally considered to be when the wavelength is bigger or smaller than the baffle, but usually done by the half wavelength. So if the half wavelength is bigger than the baffle you get the drop in bass. At least I hope that is right

5th December 2006, 02:05 AM	#3
Timn8ter diyAudio Member Join Date: Jul 2003 Location: Seattle, WA	http://www.trueaudio.com/st_diff1.htm

5th December 2006, 02:23 AM	#4
hongrn diyAudio Member Join Date: Mar 2005 Location: Placentia, CA, USA	Here's a real simple explanation: http://www.geocities.com/cc00541/index.html Hong

5th December 2006, 03:18 AM	#5
Tenson diyAudio Member Join Date: Feb 2006 Location: Kent	No kidding!

5th December 2006, 04:00 AM	#6
hongrn diyAudio Member Join Date: Mar 2005 Location: Placentia, CA, USA	Tenson, Try it again before posting.

5th December 2006, 02:44 PM	#10
Tenson diyAudio Member Join Date: Feb 2006 Location: Kent	I'm afraid the page still doesn't work for me, but never mind.

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