Fullrange with 10 inch woofer?

[DrDyna]

I don't see why it's difficult to get down into the 20s, even with a passive subwoofer. I've got a couple of Peerless 831759s here in my old corner loader cabinets that'll happily play down into the low 20s and sound great even with modest power and a simple iron core inductor and parallel cap crossover.

I'd say get a couple of these: Dayton Audio RS270-8 10" Reference Woofer 295-357

Work up a pair of boxes that your FR cabinets can sit on. Tune it down around 25 cycles or so and cross over passively to your full range at 80 - 90 cycles, or even MiniDSP it. Done.

[Josephjcole]

Originally Posted by DrDyna

Work up a pair of boxes that your FR cabinets can sit on. Tune it down around 25 cycles or so and cross over passively to your full range at 80 - 90 cycles, or even MiniDSP it. Done.

80Hz seems pretty low for a passive crossover. Pretty close to the resonant frequency of the full range driver. I've got a 4" full range driver that I crossed over passively at 300Hz. Even at 300Hz I could still measure some peaking around the resonant frequency. Putting a resistor across the terminals of the full range driver helped to some extent...

[kipman725]

There are ways of getting around room nodes such as the double bass array:
Double Bass Array (DBA) - The modern bass concept! - AVS Forum

I had a think about this and 2 feet of fiber glass on one wall and and an array on the other wall should work almost as well while reducing the cost, might cause damp problems though.

Passive crossovers are not ideal for a low crossover for a full range as you will need to compensate for the impedance peak of the driver. Unfortunatly the magnitude and frequancy of this peak will change at high drive levels and as such you crossovers characteristics will change!

*also the system in my sig is a full range with subs system that works pretty well although I have room node issues due to the enforced maximaly coupled position of my subs.

[DrDyna]

Originally Posted by Josephjcole

80Hz seems pretty low for a passive crossover. Pretty close to the resonant frequency of the full range driver. I've got a 4" full range driver that I crossed over passively at 300Hz. Even at 300Hz I could still measure some peaking around the resonant frequency. Putting a resistor across the terminals of the full range driver helped to some extent...

Well, that's just the number I have in my head because I was thinking of doing some kind of FAST system using the Markaudio Alp12 once the new generation is out and that'd be safe to use down that low.

I suppose if you're using an eensie weensie full range driver that won't play lower than a midrange then yeah.

[DrDyna]

Originally Posted by kipman725

There are ways of getting around room nodes such as the double bass array:
Double Bass Array (DBA) - The modern bass concept! - AVS Forum

I started reading that article and it seemed very interesting, until a little further down in the thread, I read this:

"A time ago I used closed boxes. But since there is no room gain with a DBA (you practically get free air conditions) I had to use a +12 dB shelving filter in the lower end. This dropped max SPL a lot, because of high cone excursion. So right now all subwoofers are vented designs."

[kipman725]

no free lunch if your fully absorbing the reflected wave the room is not there so no room gain.

[Swifty]

Actually, I am doing exactly what you are contemplating. I am now in the process of optimising the filter. I can already say with confidence however that this combinaton is working very well. I must say that without active DSP filtering this would be a lot more complicated to get right.

[DrDyna]

Very, very nice, almost exactly what I was going to try, with slightly different drivers.

[Josephjcole]

Originally Posted by DrDyna

Well, that's just the number I have in my head because I was thinking of doing some kind of FAST system using the Markaudio Alp12 once the new generation is out and that'd be safe to use down that low.

I suppose if you're using an eensie weensie full range driver that won't play lower than a midrange then yeah.

I'm not talking about running out of excursion... I talking about dealing with the spike in impedance near Fs. Like you mentioned a MiniDSP is definitely the way to go. Trying to crossover around 80Hz passively would be problematic at best...

[Inductor]

Originally Posted by Josephjcole

I'm not talking about running out of excursion... I talking about dealing with the spike in impedance near Fs. Like you mentioned a MiniDSP is definitely the way to go. Trying to crossover around 80Hz passively would be problematic at best...

Yes, problematic but for a passive crossover you have to identify the best type of crossover to have a phase match between the two drivers. That's where only some (diyAudio members) can go. And at the same time identify the problems that you address very well of the capacitance of the crossover filter (cap) with the inductance of the coil of the driver (that's going to resonate) together with the natural resonance frequency of the driver, and we don't have a horn here so we don't have to deal with that too. Solve all this problems and you are set for a passive system. Plus, you have to know what is the driver you are going to use as woofer/sub, because you need extension and at the same time a lot of (90>) SPL. So that's why I say choose your (FR) full range first and then you are half way to solve the puzzle.