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

[mcmahon48]

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

[doug20]

Cool idea, now that Zaph doesnt do measurements any more we need a new source.

[cuibono]

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.

[doug20]

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).

[gedlee]

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.

[dantheman]

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

[dantheman]

Oh, one other good site:
Driver FRD & ZMA files

[Pano]

Oh, and here I was thinking it might be a database including impedance files.
But that would be a ZMA archive, wouldn't it?

[dantheman]

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

[CLS]

Impedance curves can reveal some resonance 'problems' which might not be seen in the FR charts.