The time is now, We should build A speaker FRD data Base

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Since many of us now have Holmimpulse and many now have also the test jig to use to get Speaker FRD it would be helpful for all of us to contribute to this database plus a standard form of info in what condition for the testing would be needed.
for when I test a speaker it is out side and facing straight up into the air and is in an area that has no walls nearby to eliminate any reflections and would list box design since I try to get away from a straight box interior in my designs
 
I hope Zaph isn't out of the picture. If he is, we need someone to step into his shoes.

A speaker FRD database would be nice, but not very useful. The critical thing in doing measurements is that they are all done the same way - EXACTLY the same way. Zaph had this taken care of. If people just post graphs of the speaker they are currently playing with, it will be almost useless. There would have to be a lot of specific info to be useful, and people would have to be very thorough, both in measurement and reporting. Probably not going to happen...

Luckily, if you know how to read into the limits of data (particularly manufactures' data), you can learn a lot. Some important things aren't even reported at all (in a meaningful way) - like Xmax and power input limits.
 
I disagree. initial speaker selection comes from published measurements. 3rd party is better then manufacturer specs.

What Zaph did was allow for great comparisons too. That made speaker selection easy. We just need a larger database. Polar and CSD being the biggest ones I like.

Obviously most will measure the drivers they buy but no one buys drivers without looking at some form of measurements.

Conclusion, a database of measurements is useful.

btw, Zaph is building drivers and selling speakers now. He posted a while ago that he will not be doing free measurements any more (its a conflict of interests).
 
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I have recently spent a great deal of time and effort creating what I believe is the ideal way to look at the single most important aspect of a loudspeaker, its total polar response. I have just today posted this technique on my site - hidden on the Loudspeakers page at Loudspeakers down at the bottom of the bullet list. This is the first tme that I have developed an app for the web and its not very fast at loading the data files, which are very large. So be pateient and it should work. I now have all of the calculations required to generate such plots and all I need is a single HolmImpulse output file (with 13 off axis and one near field data set). The rest is just calcs and the program on my web can be used. Not sure how much of this I will make "public domain", but I am willing to do some data sets for others so that they can be posted in the list as well.

Let me know if you have any problems.
 
That would be great of you'd make that all public domain. It would be a great service to all audio geeks. No offense intended guys, but it's true.

I think a large database of polar graphs of woofers and T/S prams would be fantastic. Even if people could only post parts of each speaker on the site.

Right now these are where I go to look for driver information:
Zaph|Audio
Measurements
Home (drivervault)

It would even be cool just to add to this list if anyone knows of some others.

Dan
 
I have recently spent a great deal of time and effort creating what I believe is the ideal way to look at the single most important aspect of a loudspeaker, its total polar response. I have just today posted this technique on my site - hidden on the Loudspeakers page at Loudspeakers down at the bottom of the bullet list. This is the first tme that I have developed an app for the web and its not very fast at loading the data files, which are very large. So be pateient and it should work. I now have all of the calculations required to generate such plots and all I need is a single HolmImpulse output file (with 13 off axis and one near field data set). The rest is just calcs and the program on my web can be used. Not sure how much of this I will make "public domain", but I am willing to do some data sets for others so that they can be posted in the list as well.

Let me know if you have any problems.
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Thank you Dr. Geddes. It works on my PC (Vista SP2), you are correct it does take a small amount of time.

Are you saying the program may be public domain for others to insert their measurements?
 
I disagree. ... 3rd party is better then manufacturer specs.

...

Conclusion, a database of measurements is useful.

I don't want to disagree endlessly, but I'll say it for the record - if measurements of a driver are taken on baffles of various sizes, and/or the measurements are done by someone who doesn't know about what the limits of their measurement capabilities are - these measurements are going to be seriously flawed.

I've done tons of flawed measurements, over a period of years. It is very unlikely a novice will generate measurements useful to others. There are too many variable conditions.
 
I actually don't think impedance is AS important as it's easier to correct and need not be important for selecting the perfect driver for the project. It's nice to have stuff IMO.

Dan

The original idea of providing a ZMA file was so that modeling software (such as CALSOD at the time) could know the electrical load each passive crossover section would be working into. Combined with the FRD files, this let you simulate what the related total result would be at the location FRD was measured from.
 
I have recently spent a great deal of time and effort creating what I believe is the ideal way to look at the single most important aspect of a loudspeaker, its total polar response. I have just today posted this technique on my site - hidden on the Loudspeakers page at Loudspeakers down at the bottom of the bullet list. This is the first tme that I have developed an app for the web and its not very fast at loading the data files, which are very large. So be pateient and it should work. I now have all of the calculations required to generate such plots and all I need is a single HolmImpulse output file (with 13 off axis and one near field data set). The rest is just calcs and the program on my web can be used. Not sure how much of this I will make "public domain", but I am willing to do some data sets for others so that they can be posted in the list as well.

Let me know if you have any problems.

That sounds interesting - are these polar plots for drivers in boxes only? How do you compensate for the baffle geometry?

Personally, I'm mostly interested in polar measurements of totally nude drivers - combined with a good set of TS parameters. But thats just me...

EDIT: I tried to run the setup.exe, and it said it couldn't retrieve the require files, and to contact the application vendor...
 
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I don't want to disagree endlessly, but I'll say it for the record - if measurements of a driver are taken on baffles of various sizes, and/or the measurements are done by someone who doesn't know about what the limits of their measurement capabilities are - these measurements are going to be seriously flawed.

I've done tons of flawed measurements, over a period of years. It is very unlikely a novice will generate measurements useful to others. There are too many variable conditions.

Ah, I understand your POV.

Im assuming the measurements will be as accurate as what Zaph or others have provided.

Yes, I agree that flawed measurements are useless.
 
Neat program, Earl. I assume it can be used for both horizontal adn vertical?

Also, where can the files for SUMMA, etc, be downloaded? They are listed in the drop-down box, but the program says it can't find them when selected (only Piston seems to be found).

FWIW, I ran the program and saw the abbey and summa plots.

Hi Bill, the files are on my web site, but the program must be able to get to my website and it can take a very long time (Working on this). Do you get an error, or does the program just hang? If appears to hang then the data download is not complete. If it can't find the files then it will say so.

The program would work for any axis that you have the data for. In some cases I have this data, but most of the time I don't bother. Horizontal is 90% of the problem.
 
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