T/S for other than LF speakers

[dmtp]

Does anyone know where to find T/S paramenters for other than LF JBL speakers?
Specifically: LE5-5, LE25, LE85
Thanks

[grumpy]

to what end?

[remusr]

You can generate all characteristic parameters such as T-S yourself if you have access to a test tool tile WooferTester2. I got mine from PartsExpress. I have LE85's but not the other speakers you listed - I will try to do an LE85 this weekend if you still want that one. Pls confirm!
- Roy

[duaneage]

T/S parameters are used for designing cabinets and for tweeters this would not apply. For midranges your are almost ALWAYS going with a sealed enclosure and even then the idea is to protect the driver from the woofer, not add bottom end.

The LE5-x drivers have an FS around 250-300 hz, you would be crossing them over at 800-1500 hz, well above the point of a cabinet making much difference anyway.

[dmtp]

Maybe I'm wrong, but I thought T/S parameters were also helpful in designing XO circuits and predicting overall system response. That was my interest. I do not have XO design software yet, but I noticed that X-over Pro comments that they "make full use of T/S parameters" Comments?

[Zilch]

Xover3P does require T/S for all drivers, though I have not yet been able to ferret out which ones, specifically, for mids and tweets.

Fortunately, this site has them for 243x, which is what I've used it for.

It also wants response curves for full rendition, which I have measured with RTA, averaged, and input manually....

[duaneage]

No matter how much you use a design program your going to have to test and determine the results. At least if you want to have them sounding the best they can.

[dmtp]

No matter how much you use a design program your going to have to test and determine the results. At least if you want to have them sounding the best they can.

That is obvious, but I thought it would be interesting (?instructive) to run the standard JBL driver and XO info throught the program and see what it predicts. That might suggest some changes / tweaks that would, of course, have to be verified by testing.

[duaneage]

The T/S parameters will tell you what the motor and cone assembly are doing with respect to each other. For midrange and tweeters a far more important variable is the directivity or dispersion. This greatly affects the sound and can determine driver placement on the baffle, distance between them and the best slope to use. Rising response is a common trait that can either be worked into the design, controlled with a Zobel, or eliminated with a lower crossover point.

A good rule of thumb is to work with as flat an impedance as possible and to stay away from the resonant frequency. Some crossovers go to great lengths to dampen the resonant frequency and use a driver at lower frequencies, and then cross over the driver at a high slope to protect it. Such practices may have merit but are hardly necessary when using correctly matched drivers is a better solution.

Midranges have limited cone movement and small Sd , producing a Vas that is very small and hard to measure accurately. This can cause errors in designing enclosures for these drivers.