[Group6]

Where would you start with a crossover for a 55-1870 model speaker? We don't have any idea. Also, what kind of inductors and capacitors would you use?

[S Clark]

Do some reading on crossovers- until you understand what the parts of a first and second order crossover are doing, then we might as well be speaking Greek.  See the other threads about this in the Junior Audiophile circle.  Look at the Parts Express projects, look at the Zaph Audio for 5" projects. 

This is discussed in another thread in this circle.  Read it.  http://www.audiocircle.com/index.php?topic=79562.0

[DanTheMan]

Could you post a link to the driver?

Thanks

[S Clark]

Could you post a link to the driver?

Thanks

Not really.  They are 9mm Al Taiwan drivers that we got from Dave Elledge. They seem to be reasonably well made, with rubber surrounds and hefty magnet structures.  I measured it with a dos based Clio and can't seem to transfer files.  I'll take a digital photo of the screen and post it.

[Duke]

In theory a 5" woofer will go up high enough to match up reasonably well with most tweeters, but you'd want to know what its frequency response curve looks like so that you can try to avoid or minimize any nasties.   Ideally, you'd choose woofer and tweeter based on how well they will work together.

In the absence of any data on the woofers's frequency response, I'd say try to cross over as low as your tweeter will safely allow and as steeply as your budget and crossover knowledge will allow.  Generally tweeters are better-behaved at their bottom end than woofers are at their top end, as long as you don't overdo it and stress the tweeter. 

In order to begin to design a decent crossover, you will need the frequency response curve and the impedance curve of both woofer and tweeter.   

One other tip:  Let the tweeter's response sag by two or three dB in the octave or so above the crossover frequency.   The tweeter will have a very wide radiation pattern just above the crossover region, and this response dip will help compensate for the extra energy it's putting out to the sides.  Credit to the BBC for coming up with this idea way back when I was a kid.

Duke

[Danny Richie]

I can't emphasize enough what Duke said. Read it through twice. 

Then post your measured responses for additional help.

[S Clark]

Ok, here is a screen shot and a photo of the driver.



I've definitely seen worse breakups in aluminum drivers. Fairly flat through the baffle step loss.   Not bad.




Here it is in a test box. 

[Danny Richie]

Just a thought, but when measuring it, are you setting it on a box like the one in the photo? If so it will add to the baffle size and give it a little lift in the 500 to 600Hz range.

Looks like the break up is pretty high on that one so that will really help.

I also know that tweeter can be crossed pretty low.

So crossing it in the 2kHz to 2.5kHz range with a second order crossover might be pretty easy.

[S Clark]

Just a thought, but when measuring it, are you setting it on a box like the one in the photo? If so it will add to the baffle size and give it a little lift in the 500 to 600Hz range.

Yep, that is exactly what I did.  Should I try to create an adjustable setup like yours?  How severe a lift are we talking about? 3 dB?

[Danny Richie]

Yep, that is exactly what I did.  Should I try to create an adjustable setup like yours?

I bought the stand I use from Parts Express.

How severe a lift are we talking about? 3 dB?

I bet it is at least 1.5db in that range. I'll let you tell me how much it is. 

[HAL]

Here is a link to the driver at MCM:

http://www.mcmelectronics.com/product/MCM-AUDIO-SELECT-55-1870-/55-1870

EDIT:  There maybe some differences between these and Dave's units. 

[S Clark]

Thanks Hal, and thanks for the donation of them.  Looking back through your PM's I see that they were MCM drivers.  They are well built and will work well.  Several groups are using them.

[HAL]

Scott,
Glad to help!