How to pick a crossover freq?

kraigo · #1 12-06-2010, 01:41 PM

The saga continues. Since most of this stuff is hypothetical at this point, it's not even a sad saga.

I have a Parts Express/Dayton 10" woofer. The T/S params show it to be pretty similar to an Eminence BP102. I'm guessing the PE/Dayton woofer was OEM'd by Eminence, but I don't really know that.

Question #1: The WDR file I made for the woofer doesn't show me any high end roll-off. I've made WDR files for the BP102-4 and they show the roll off. What T/S parameter does one need to add to WinISD to see where the roll-off occurs.

I can guess by using a frequency generator, but I'd like to know what it models as.

Anyway, last night I made a $25 offer (plus $12 shipping) on an Eminence Alpha 6A. which was accepted. I'm pretty sure that the Alpha 6A will _WAY_ overpower the Dayton woofer and I'm planning on an L-Pad.

But first things first.

Question #2: If there's a good sized overlap between the high end of the woofer and the low end of the mid, what are the rules of thumb for picking your cross-over frequency?

More on this project as it progresses. It seems like a fun one (at least until it goes from theory to reality).

KO

greenboy · #2 12-06-2010, 01:47 PM

Here's one of many considerations:

driver diameter & pistonic beaming frequencies

There is a lot more to it than that which I've typed way too much text about in fEarful and other threads, but it's a place to start.

kraigo · #3 12-06-2010, 01:53 PM

Thanks. I'm working through the fEarful threads already. I'll look at the link at home tonight.

I'm sure you know the answer to the question about not seeing the high end roll-off in WinISD for the WDR file I made from the only T/S Params I have for the woofer. I'm not complaining, mind you. Any quick pointers? I think I was pretty thorough creating it, so I may just be SOL.

Learning is FUN!!! At least until test time.

KO

billfitzmaurice · #4 12-06-2010, 02:53 PM

Measure the woofer response, you generally want to go no higher than where it falls to -6dB at 30 degrees off-axis relative to axial.

Quote:

What T/S parameter does one need to add to WinISD to see where the roll-off occurs.

No program can accurately predict even on-axis response more than 3 octaves above Fb, let alone off-axis.

kraigo · #5 12-06-2010, 06:28 PM

Coincident hyper-cardioids at dawn?

KO