Speaker enclosure resonance.

[Rickster71]

Speaker enclosure resonance:
I've often heard, that few speakers were void of cabinet resonance; with B&W 800D and / or 801D's being in the afore mentioned group.

So, I'm trying to come up with an 'at home test' to detect cabinet resonance.
I want to say up front, this is a very low tech method; please bare with me.
Armed with three CD's Porcupine Tree, Joe Satriani and, O.A.R.; I figured that was a pretty diverse test group.

I have Paradigm S-8's, so they were my first test victims.
I put on the first CD, and turned up the volume.
I proceeded to crawl around my speaker, with my ear up against the side of the enclosure.
Moving from the bottom of the speaker to the top. I tried to hear any vibration, or sound coming through
the enclosure's side.
Understanding I wouldn't get the entire sound spectrum in one song or CD.
I listened to all three CD's over the course of a few days. All with my ear pressed up against the speaker.
I heard absolutely nothing through the ear that was pressed to the speaker; nor did I feel any vibration.

So, is my test simply bad methodology, or am I simply not understanding what enclosure resonance is?
Any thoughts, greatly appreciated,
Rick

 

[Alex2507]

I think what is meant by resonance is a frequency built up inside the cabinet that comes out of the speaker cone making a test tone non linear. I think.

 

[Sheep]

Resonance is cabinet vibrations coloring the sound.

Ask WmAx to post pictures of his resonance free speakers and what it took to make them that way.

Your S8's are nice speakers, but they still suffer from Cabinet resonance.

SheepStar

 

[billy p]

I had read an article which stated that all well built speakers are measured by how flat they measure on a graph. Apparently in this case it sounded terrible? The best way to measure a speaker is a DBT after all your ears are the most important tools when IMO comes to testing a speaker.

Just my 2 cents, Billy P

 

[avaserfi]

Speaker enclosure resonance:
I've often heard, that few speakers were void of cabinet resonance; with B&W 800D and / or 801D's being in the afore mentioned group.

So, I'm trying to come up with an 'at home test' to detect cabinet resonance.
I want to say up front, this is a very low tech method; please bare with me.
Armed with three CD's Porcupine Tree, Joe Satriani and, O.A.R.; I figured that was a pretty diverse test group.

I have Paradigm S-8's, so they were my first test victims.
I put on the first CD, and turned up the volume.
I proceeded to crawl around my speaker, with my ear up against the side of the enclosure.
Moving from the bottom of the speaker to the top. I tried to hear any vibration, or sound coming through
the enclosure's side.
Understanding I wouldn't get the entire sound spectrum in one song or CD.
I listened to all three CD's over the course of a few days. All with my ear pressed up against the speaker.
I heard absolutely nothing through the ear that was pressed to the speaker; nor did I feel any vibration.

So, is my test simply bad methodology, or am I simply not understanding what enclosure resonance is?
Any thoughts, greatly appreciated,
Rick

Using your methodology it would be possible to hear the cabinet resonance, but you would need the source to excite the resonant bands of the cabinet. To do this the source needs to play the actual frequencies in which the cabinet is prone to resonance. I have found that well recorded classical performances with acoustic instruments and pianos work best for the ear to the cabinet test. Basically you will hear the cabinet produce a frequency on top of the frequencies the drivers are producing almost like a test tone being created from the cabinet itself.

 

[avaserfi]

I had read an article which stated that all well built speakers are measured by how flat they measure on a graph. Apparently in this case it sounded terrible? The best way to measure a speaker is a DBT after all your ears are the most important tools when IMO comes to testing a speaker.

Just my 2 cents, Billy P

Well, first off there are very many different methods that can be used to measure a speaker. For resonance to show up on a frequency response graph one would need to do multiple impulse response measurements at various angles in an anechoic chamber and then average all the measurements together. This methodology would show the actual coloration in a speaker due to resonance, but is rarely performed due complexity and cost. Also, complete linearity of response has been shown to be perceived has harsh a gradual roll off is actually perceived as tonally accurate.

There have been numerous studies done on perception of loudspeakers and its correlation to actual measurements. I would refer you to Floyd E. Toole's work for AES.

 

[Alex2507]

Resonance is cabinet vibrations coloring the sound.

Ask WmAx to post pictures of his resonance free speakers and what it took to make them that way.

Your S8's are nice speakers, but they still suffer from Cabinet resonance.

SheepStar

http://forums.audioholics.com/forums/showpost.php?p=332680&postcount=14

I think these might be the pic's you're thinking of.

 

[avaserfi]

http://forums.audioholics.com/forums/showpost.php?p=332680&postcount=14

I think these might be the pic's you're thinking of.

While those speakers are extremely well dampened compared to most commercial or DIY speaker, WmAx has told me there are still some audible resonant bands that are occasionally excited.

 

[Rickster71]

Using your methodology it would be possible to hear the cabinet resonance, but you would need the source to excite the resonant bands of the cabinet. To do this the source needs to play the actual frequencies in which the cabinet is prone to resonance. I have found that well recorded classical performances with acoustic instruments and pianos work best for the ear to the cabinet test. Basically you will hear the cabinet produce a frequency on top of the frequencies the drivers are producing almost like a test tone being created from the cabinet itself.

So I just haven't hit the resonance frequency of my cabinets yet.
Testing it with different CD's is just hit or miss.

 

[WmAx]

So I just haven't hit the resonance frequency of my cabinets yet.
Testing it with different CD's is just hit or miss.

I find it rather unlikely that no vibration could be felt on your cabinets, as you implied earlier. Perhaps for some reason, you did not realize it?

Anyways, block off one ear(use an ear plug so that the other ear's pick up does not distract you), and use your technique pressing the open ear up to the enclosure side, while playing at a moderate to high volume. You should easily hear some narrow banded noises of the music in the lower and middle mid-range on a regular speaker cabinet. Most any music will excite the resonance, it's just that some will excite it more.

-Chris

 

[Rickster71]

I find it rather unlikely that no vibration could be felt on your cabinets, as you implied earlier. Perhaps for some reason, you did not realize it?

Anyways, block off one ear(use an ear plug so that the other ear's pick up does not distract you), and use your technique pressing the open ear up to the enclosure side, while playing at a moderate to high volume. You should easily hear some narrow banded noises of the music in the lower and middle mid-range on a regular speaker cabinet. Most any music will excite the resonance, it's just that some will excite it more.

-Chris

I'll try your suggestion with the ear plug.
Maybe I'll use my good ear this time.