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Multi-Way Conventional loudspeakers with crossovers

Multiple 12-ish ohm drivers in a 2.5 way? no way?
Multiple 12-ish ohm drivers in a 2.5 way? no way?
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Old 11th July 2018, 01:04 AM   #11
JMFahey is offline JMFahey  Argentina
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Those definitely are 16 ohm 10" speakers.
Two of them in parallel would be a standard 8 ohm load which can be driven by practically any amplifier.
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Old 11th July 2018, 03:23 AM   #12
G Speakers is offline G Speakers  United States
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Originally Posted by hollowboy View Post
You could sell some of them, and use the money for parts for make a 3-way.
These are used, but in VERY good health from what I have measured. I am connected to d&b through my career in live sound and they are fairly protective of who gets their stuff so I don't want to mess with our relationship. But man, it's tempting cause this stuff is expensive!



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1) You need the midbass section to be ~80cm tall to get the horn to ear height, so an enclosure volume of about 100 litres seems reasonable.
I prefer HF a little higher, but yes, you're right, I've got lots of room here to play with.


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Originally Posted by hollowboy View Post
- four x 10" (in series-parallel, nominally 16 ohm), bass only.

That'd give you a 'normal' nominal 8 ohm load. The crossover on the bass quad could possibly be as simple as one humungous inductor.
I get the concept, and I like it. But what am I missing with getting 4x16ohm woofers into an 8ohm load? I end up with 8(P)+8(P)=16, 32(S)+32(S)=16, or all parallel at 4Ohm.

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You wouldn't have to mount the 5 drivers woofers on the front panel. The bass quad (or half of it) could go onto the sides.
Ya, unfortunately I have only poor speaker locations available and I'm concerned that proximity to the walls would very negatively impact any sort of dipole. Am I thinking about that correctly? Plus, in general, forward facing I think is safer in unforgiving environments.
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Old 11th July 2018, 03:29 AM   #13
G Speakers is offline G Speakers  United States
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I was thinking something similar in terms of dipoles, Hollowboy.
Do think this requires some active to leverage the extra surface area down low.

I'm on my phone, G, so I'll dig up some material soon. Look up tapered quarter wave pipes. They're yet another helmholz resonator.
Ahhh, I see. What software can do these calculations? Or do I need to break out the calculator? I'm familiar with bass box, Jeff Bagby's stuff, and WinISD (a little) as far as predictions go.
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Old 11th July 2018, 04:57 AM   #14
hollowboy is offline hollowboy  Australia
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Quote:
Originally Posted by G Speakers View Post
I get the concept, and I like it. But what am I missing with getting 4x16ohm woofers into an 8ohm load? I end up with 8(P)+8(P)=16, 32(S)+32(S)=16, or all parallel at 4Ohm.
I was assuming a passive crossover. If you're using active, then yea, it makes no sense.

If you go passive with a simple 1st order passive crossover, then:

Midbass is a small inductor in series with a ~16ohm woofer.
...if you ran this in isolation, the DC resistance would be about 12ohm (16ohm nominal).

Bass is a huge inductor, then 4 woofers (A, B, C and D) arranged in series-parallel, so the signal can go through:

A-and-B (32ohm nominal)
OR
C-and-D (32ohm nominal)

...if you ran this in isolation, the DC resistance would be about 12ohm (16ohm nominal).

If the midbass and bass were run from a single amp (in parallel), the DC resistance would be about 6ohm (8ohm nominal, i.e. "normal").

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Originally Posted by G Speakers View Post
Ya, unfortunately I have only poor speaker locations available and I'm concerned that proximity to the walls would very negatively impact any sort of dipole. Am I thinking about that correctly? Plus, in general, forward facing I think is safer in unforgiving environments.
I'm no expert, so take this with a grain of salt:

- In a sealed or ported box, putting LF drivers on 3 faces would still be a monopole, not a dipole (you'd get an omni bass pattern, not figure 8).

- slot loaded 12" woofers are supposed to be fine up to about 300Hz (according to people who build PPSL boxes), so as long as the wall clearance on your (bass only) speakers was bigger than a PPSL plenum, I think you'd be OK.
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Old 11th July 2018, 06:06 AM   #15
DPH is online now DPH  United States
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Originally Posted by G Speakers View Post
Ahhh, I see. What software can do these calculations? Or do I need to break out the calculator? I'm familiar with bass box, Jeff Bagby's stuff, and WinISD (a little) as far as predictions go.
The developer of hornresp is a wonderful gentleman who frequents this site regularly: David McBean

You can find him here: Hornresp

His software is great for just this purpose.

My reservation about TM(M^4) is how low that BSC is likely to be, where having an active + passive would bypass that monstrosity. But bigger things have been done passive than this.
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Old 11th July 2018, 01:01 PM   #16
G Speakers is offline G Speakers  United States
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I was assuming a passive crossover. If you're using active, then yea, it makes no sense.
Ok, I read this when I was way too tired last night. This makes perfect sense now, I just wasn't thinking straight. Also whiskey. . . .

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Originally Posted by hollowboy View Post
- slot loaded 12" woofers are supposed to be fine up to about 300Hz (according to people who build PPSL boxes), so as long as the wall clearance on your (bass only) speakers was bigger than a PPSL plenum, I think you'd be OK.
Ya, I just don't think I can convince my wife of it
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Old 11th July 2018, 01:06 PM   #17
G Speakers is offline G Speakers  United States
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Originally Posted by DPH View Post
The developer of hornresp is a wonderful gentleman who frequents this site regularly: David McBean
I was just looking at this. Looks great, thanks!


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Originally Posted by DPH View Post
My reservation about TM(M^4) is how low that BSC is likely to be, where having an active + passive would bypass that monstrosity. But bigger things have been done passive than this.
What's wrong with having a low BSC? You mean just because thats the region I'm concerned about to begin with? Also, having an active also I'm assuming would have to be a different driver since these just don't get down there. FWIW these may end up in my HT setup which obviously has an active sub already. I need to build new surrounds anyway. Might as well just take over my shop for this
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Old 11th July 2018, 02:18 PM   #18
DPH is online now DPH  United States
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A low bsc (or rolling in the additional woofers I should say) will require a big inductor, the kind that may be pricey. The second reservation about using 4 woofers in the .5 section is that they will need to be resistively padded down to match the top, killing a big portion of the advantage. Third, active would give us better access to bass boost to leverage that huge displacement.

I realize that adds a couple layers of complexity, so feel free to ignore it!
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