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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Next up is an IMD test of 9" woofers. This test will compare the Morel TSCW 938 and the Satori WO24TX-4. Both drivers have advanced cones, Carbon Fiber/Rohacell sandwich for the Morel and TeXtreme for the Satori. Same 14 liter sealed box testing method as the 8" drivers was used.
The Satori WO24TX-4 is very capable in clean bass output, average max output from 25-63hz while staying under 5% distortion it averaged 96.6 db while the larger 10" Seas L26 Roy averaged 95.0db. While performing listening tests, I had an issue with the Satori vibrating my light fixtures to the bassline of the music!
In most of the IMD tests the Satori was better, however the Morel was cleaner in the 300hz IMD test. I believe this is due to a higher efficiency and a larger coil. The Morel is less capable in deep bass, however it did excel in something I am unable to measure and that is providing a quicker decay or blank space in between mid to upper bass notes.
The Satori WO24TX-4 is very capable in clean bass output, average max output from 25-63hz while staying under 5% distortion it averaged 96.6 db while the larger 10" Seas L26 Roy averaged 95.0db. While performing listening tests, I had an issue with the Satori vibrating my light fixtures to the bassline of the music!
In most of the IMD tests the Satori was better, however the Morel was cleaner in the 300hz IMD test. I believe this is due to a higher efficiency and a larger coil. The Morel is less capable in deep bass, however it did excel in something I am unable to measure and that is providing a quicker decay or blank space in between mid to upper bass notes.
Attachments
What are chances of measuring different woofers from the same manufacturer?
eg. Alpine subwoofers
Take a look at these curious things:
eg. Alpine subwoofers
Take a look at these curious things:
Cool video Tktran, In the 8-9" size I've tested the SB SB23MFCL45-4 which is the same manufacturer as the Satori. I've also tested quite a few different Dayton Audio drivers in the 6-7" size.
The attached chart has all my bass IMD results in drivers 5-10". I am also thinking about how I will include the midrange IMD data in the chart. Any suggestions? Maybe just signal to noise?
The attached chart has all my bass IMD results in drivers 5-10". I am also thinking about how I will include the midrange IMD data in the chart. Any suggestions? Maybe just signal to noise?
Cool video, but I mean designing a driver with a surround that can't keep up with the cone excursion is not the right way of doing it.
Or you just simply use the driver for something that it was not designed for.
In general getting large signal parameters + motor stability tests tell a lot more.
Stability in stiffness is heavily dependent on excursion as well as frequency.
So looking at one use case doesn't say much.
To actually answer the first question from a quality point of view.
I have dealt with production numbers in the hundreds.
It really differs per brand/manufacture, some are spot on, some are absolutely terrible
@tktran303: nice video, but is there anything unexpected to be seen?
In my simple view all three surrounds do what they are supposed to do in a rather controlled manner.
These images are very different from some of the YT video's showing Car Audio subwoofers under extreme excursions, where the surround more or less collapses.
In my simple view all three surrounds do what they are supposed to do in a rather controlled manner.
These images are very different from some of the YT video's showing Car Audio subwoofers under extreme excursions, where the surround more or less collapses.
I call that being used beyond their capabilities.
Most car audio subs are also not designed all that well in my experience.
But you will immediately see this with some proper Klippel (or equivalent) large signal testing.
Obviously seen from a audio reproduction perspective.
I mean, if their goal was to just show off (misbehavior), they succeeded 😀 😀
In the video it looks like the normal surround has some ringing or bounces as the surround gets stretched to it's max. I don't see this with the other two.
Thanks shrub0, imo MUCH more useful to see all of it in one sheet of a spreadsheet 👍
Though they’re only tested up to 90 dB. That’s ok for casual listening and or if your speakers are reasonably close. Have you considered doing it over a higher range eg 80, 90 and 100? eg Erin tests speakers at 85, 95 and 105. I’m sure you know what happens to SPL each time the listeners distance doubles
While I’m thinking about it, what about, so testing doesn’t take as long just do it at two levels. For example 85 and 105
Thanks for the suggestion Otto88, I did carry out my large box 10" subwoofer test to 100db: https://www.diyaudio.com/community/threads/10-woofer-subwoofer-imd-comparison.391184/post-7519345
Since I'm using constant tones and it takes a few seconds for me to calibrate the levels I'm always a little leery of going too loud. I did burn one voice coil but this isn't too bad considering I've done over 40 drivers so far.
Since I'm using constant tones and it takes a few seconds for me to calibrate the levels I'm always a little leery of going too loud. I did burn one voice coil but this isn't too bad considering I've done over 40 drivers so far.
The traditional ones are single roll, double roll, triple roll (or multi roll) and inverted roll.
In this case we have some fancy one, which they call "double gathered", see the 1:40 time stamp.
In this case we have some fancy one, which they call "double gathered", see the 1:40 time stamp.
I find it really challenging to be certain that the excursion is exactly the same across all tests.
Since the drivers aren’t even the same to start with, it’s difficult to predict how the motor might affect anything.
Let alone to know how this translates to actual large signal data and therefor jump to conclusions.
When I watched the video I can see that the conventional half roll rubber surround indeed exhibits Sd(x) variation. Or what @lrisbo means about the Sd is at the maximum when the cone excursion is all the way IN, and at a minimum when the cone is all the way OUT.
With YouTube’s ability to slow down the (slow-motion) video, is the HAMR, or double gathered surround better than the half roll?
I’m not sure.
With YouTube’s ability to slow down the (slow-motion) video, is the HAMR, or double gathered surround better than the half roll?
I’m not sure.
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Could you clarify how this proves the excursion is the same?
It would also be helpful to know the effective Sd in general, as that information would be interesting.
Without actual data, Sd(x) still doesn’t provide concrete numbers for us to work with, so it remains more of a hypothesis at this point, until actual numbers are shown as evidence.
It would also be helpful to know the effective Sd in general, as that information would be interesting.
Without actual data, Sd(x) still doesn’t provide concrete numbers for us to work with, so it remains more of a hypothesis at this point, until actual numbers are shown as evidence.