Prevent Small Full Range Driver From Overextending Itself

[mondogenerator]

Yes, the mid TL is stuffed until aperiodoc or close to. Its a very useful technique to make low crossovers work predictably. Its something ive been meaning to try for a while

[chrisb]

Originally Posted by Ben_Tech

Thanks for the responses guys (Dave).... I have a question about that design you pictured.... it looks as though the chamber for the FF85 is open at the back? I assume you are heavily stuffing that small space to make it aperiodic? Or is it more complex than that?

Progressive density of the fill and the pronounced taper of the chamber is what we used with the FF85K in Tysen, as well as the MTM with CSS EL166 mid-woofs - it worked out well enough in both cases. IINM the measured curves to which Ryan referred were for the Tysen?

[planet10]

Originally Posted by Ben_Tech

Thanks for the responses guys (Dave).... I have a question about that design you pictured.... it looks as though the chamber for the FF85 is open at the back? I assume you are heavily stuffing that small space to make it aperiodic? Or is it more complex than that?

Yes, Yes (but not uniformly and not all the same material), No.

Can the small aperiodic space achieve that or are we still needing a filter?

Aperiodic gives up an order to sealed and needs the filter... it is just that the filter is more effective. The aperiodic line also "sucks" the back wave away so you get less time-smeared reflection back thru the cone cleaning up the midrange.

Any drivers better than FF85 for this application? I.e., still offering "the best" mids and highs but higher acoustic roll off?

Alpair 6.2m offers similar performance, it won't give a higher acoustic rolloff, but goes lower, with a smaller peak at resonance. Higher bass output capability means that it has more room to move before overextending itself.

Is the heat dissipation issue with the amp bass power still being applied too much for safety?

No more than in any other application. You have to play pretty loud to start a fire.

dave

[Ben_Tech]

Originally Posted by planet10

You have to play pretty loud to start a fire.

dave

That gave me a chuckle. Dry Canadian humor, perhaps.

Thanks again for all of the great info, more to think about!

[sreten]

Originally Posted by Ben_Tech

Most full range drivers can't take much punishment which is why I'm
thinking about this at all.

However, I firmly believe "less is more" with audio in general, thus hoping
someone has tried an unfiltered full ranger in a small cabinet or some other
creative enclosure to curtail it sufficiently to do a FAST of sorts without a
filter on the FR. I know most FAST use bi-amping with an active filter
before the amps. However, I can't do that.

Hi,

So just build a FAST with a minimum 1st order series x/o.
Will solve excursion problems in one stroke.
250 to 400Hz, depending on baffle width, bass driver size.
Triangulate the top of the box for the FR, or front to back tube.

rgds, sreten.

[chrisb]

Originally Posted by sreten

Hi,

So just build a FAST with a minimum 1st order series x/o.
Will solve excursion problems in one stroke.
250 to 400Hz, depending on baffle width, bass driver size.
Triangulate the top of the box for the FR, or front to back tube.

rgds, sreten.

like this:?

[mondogenerator]

P10, chris, Sreten- Am I correct in thinking that a 1st order series filter is best suited for the OP? In comparison to a parallel 1st order network.

[planet10]

Originally Posted by mondogenerator

P10, chris, Sreten- Am I correct in thinking that a 1st order series filter is best suited for the OP? In comparison to a parallel 1st order network.

This has been our experience. And it is the one kind of XO that has at least one advantage over any active XO.

dave

[chris661]

Yep, series first order XOs are nice in that they compensate for impedance changes, resulting in a flat response again (albeit with the XO point and Q altered slightly).

I'd expect the benefits of taking the LF duties off the smaller driver would outweigh the downsides of a simple XO.

Chris

[Ben_Tech]

Great! A first order series network it is then, probably at 300 Hz. Do you fellows think that a crossover in that range would detract from vocal intelligibility? I like to hear the lyrics.