My preferred way is to do tests objectively.
And I am just wondering (out loud) if the current setup provides that and how/if this will affect the results.
Nothing more, nothing less.
Running woofer tests is difficult. There’s no doubt about it.
@shrub0 is providing this data for free, using his own money. For sure he could have kept the results to himself. He certainly isn’t getting anything for publishing them online.
The results may be internally valid- ie. in 1/2 cu ft cabinet measured at 1.5m in room using ground plane method.
Does that means it’s externally valid? (generalisable for all other settings?) There may be indeed limitations there. As @shrub has previously alluded to, perhaps the box may be marginally too large or too small for the woofer. Or that is mic has own self distortion that may be exceed if tested in a semi near field setting. Or that he doesn’t have an anechoic chamber or Klippel NFS.
How should/could future tests be conducted?
And what would the process look like?
Only with further testing can we know more.
Data-bass.com settled on a standard which was 4 cu ft for 18” woofers. Unequalised. Played up to its distortion limits according to the CEA2010 standard.
Tim Feleppa measured all his 5-8” woofers in a quasi IB panel, equalised to the cone and equalised so that the near field (2pi) response it within 1dB of a 40Hz 2nd order Butterworth highpass response from 40Hz to 200Hz.
http://feleppa.com.au/speakermeaswoofer.html
However, they also have their own limitations- they didn’t measure IMD.
We value your experience @b_force ; so we would love a proposal on a methodology for testing IMD that can be conducted indoors, and at various SPL levels.
I too have conducted my own tests. It’s on an IEC baffle, with removable 1 ft squared inserts. Limitations of that? Well, it’s a pain in the **** !
So I do have some data that probably only a handful of people have seen. Certainly I have no seen them elsewhere.
And every so often I think maybe it will be interesting for people to know what I’ve learnt. Do I dare go out on a limb and publish them?
But people will ask- where did you get those unobtainium drivers? Are they authentic? How much did you pay for them? You must be in the loudspeaker industry! Why won’t you tell us? You are playing favourites!
And so I step back into anonymity. I don’t want too many people to spit out their coffee in early morning disbelief! 😜
@shrub0 is providing this data for free, using his own money. For sure he could have kept the results to himself. He certainly isn’t getting anything for publishing them online.
The results may be internally valid- ie. in 1/2 cu ft cabinet measured at 1.5m in room using ground plane method.
Does that means it’s externally valid? (generalisable for all other settings?) There may be indeed limitations there. As @shrub has previously alluded to, perhaps the box may be marginally too large or too small for the woofer. Or that is mic has own self distortion that may be exceed if tested in a semi near field setting. Or that he doesn’t have an anechoic chamber or Klippel NFS.
How should/could future tests be conducted?
And what would the process look like?
Only with further testing can we know more.
Data-bass.com settled on a standard which was 4 cu ft for 18” woofers. Unequalised. Played up to its distortion limits according to the CEA2010 standard.
Tim Feleppa measured all his 5-8” woofers in a quasi IB panel, equalised to the cone and equalised so that the near field (2pi) response it within 1dB of a 40Hz 2nd order Butterworth highpass response from 40Hz to 200Hz.
http://feleppa.com.au/speakermeaswoofer.html
However, they also have their own limitations- they didn’t measure IMD.
We value your experience @b_force ; so we would love a proposal on a methodology for testing IMD that can be conducted indoors, and at various SPL levels.
I too have conducted my own tests. It’s on an IEC baffle, with removable 1 ft squared inserts. Limitations of that? Well, it’s a pain in the **** !
So I do have some data that probably only a handful of people have seen. Certainly I have no seen them elsewhere.
And every so often I think maybe it will be interesting for people to know what I’ve learnt. Do I dare go out on a limb and publish them?
But people will ask- where did you get those unobtainium drivers? Are they authentic? How much did you pay for them? You must be in the loudspeaker industry! Why won’t you tell us? You are playing favourites!
And so I step back into anonymity. I don’t want too many people to spit out their coffee in early morning disbelief! 😜
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@tktran303
Where can you read that I ever had critique or problems with the effort that's being put into?
Can't really appreciate such assumptions at all, those are two entirely different things.
The only thing I am doing is discussing the way it's being tested.
I think everyone here has the right to do so and share his/her opinions.
On a public discussion forum that is ALWAYS a two way street, if you like it or not.
I respect other peoples opinions, I hope other people do the same.
If you don't want ANY well meant ideas or thoughts on what you're doing, simply don't post it.
Fyi, on exactly the same page, you also do realize that there are quite some (ex) professionals or very involved people on this forum, giving their experience and knowledge 100% for free.
Maybe you should also think about what that means in sense of how valuable that is.
Because sometimes there is a reason those people respond you know....
(and that reason is NOT to just attack or offend you btw!!)
Anyway, take it or leave it, case closed for me.
Where can you read that I ever had critique or problems with the effort that's being put into?
Can't really appreciate such assumptions at all, those are two entirely different things.
The only thing I am doing is discussing the way it's being tested.
I think everyone here has the right to do so and share his/her opinions.
On a public discussion forum that is ALWAYS a two way street, if you like it or not.
I respect other peoples opinions, I hope other people do the same.
If you don't want ANY well meant ideas or thoughts on what you're doing, simply don't post it.
Fyi, on exactly the same page, you also do realize that there are quite some (ex) professionals or very involved people on this forum, giving their experience and knowledge 100% for free.
Maybe you should also think about what that means in sense of how valuable that is.
Because sometimes there is a reason those people respond you know....
(and that reason is NOT to just attack or offend you btw!!)
Anyway, take it or leave it, case closed for me.
I’m with you.
But the delivery, and how it’s received, or may be perceived, is also important. Perhaps even more so.
Communicating is a two way street, is it not?
One of the downsides of this forum is that the editing time is only 30 minutes. If I have had a night of poor sleep, sometimes what i write comes off as slightly sarcastic. I try to (re)consider what I write may cause unintentional offence. I often couch my writing in gentler terms.
Sometimes, even when I know, or think I know, in no uncertain terms, that I am correct. I will use Consider, instead of “You should…”
We used to think that gravity is a force that exists between two massive objects (Newtonian). Now we know that it is more correctly described as a curvature in spacetime (General relativity)
Knowledge and Science is ever evolving. Even professionals, like myself, or yourself, can later shown to be wr.. not quite correct.
So before we criticise, we should offer alternatives, I think.
In fact, if I am position of authority, perhaps I have an even greater duty to be of service, as an advisor.
If you disagree with these thoughts, I’m ok with this.
I respect your input, as always.
But the delivery, and how it’s received, or may be perceived, is also important. Perhaps even more so.
Communicating is a two way street, is it not?
One of the downsides of this forum is that the editing time is only 30 minutes. If I have had a night of poor sleep, sometimes what i write comes off as slightly sarcastic. I try to (re)consider what I write may cause unintentional offence. I often couch my writing in gentler terms.
Sometimes, even when I know, or think I know, in no uncertain terms, that I am correct. I will use Consider, instead of “You should…”
We used to think that gravity is a force that exists between two massive objects (Newtonian). Now we know that it is more correctly described as a curvature in spacetime (General relativity)
Knowledge and Science is ever evolving. Even professionals, like myself, or yourself, can later shown to be wr.. not quite correct.
So before we criticise, we should offer alternatives, I think.
In fact, if I am position of authority, perhaps I have an even greater duty to be of service, as an advisor.
If you disagree with these thoughts, I’m ok with this.
I respect your input, as always.
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