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PostPosted: 21 Jan 2009, 14:35 
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Joined: 18 Jan 2009, 17:35
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"Series is wiring the + of one speaker to the - of another and then the amp to the remaining + and - giving 8Ohms"

OK guys, thanks. (I think) I now know what I need to try this. I am going to test this out on the cherry cabinets of the JVC speakers themselves -- doubled series-wired full-range drivers, forward-firing with one on the baffle and one interior, directly behind with a second baffle inside the cabinet.

If this works and bass is extended, I shall redo the cabinets, milling them from solid rock -- two blocks of banded iron-formation (I am a geologist, after all). Pics and responses to follow...

cheers,
D


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PostPosted: 21 Jan 2009, 14:56 
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Youre making me drool. You guys have to stop it with the rock cabs! Its so far from reach for the rest of us! :)
Ri

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PostPosted: 23 Jan 2009, 12:51 
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And, on reflection, one more question!

i) If the two series-wired drivers running in cone-to-magnet isobaric form are full-range (which they are), then will this low-frequency-friendly setup colour the sound at mid and higher frequencies? Isobaric / coupled-cavity loading seems to good for lowering main-driver resonance, ideal free-space loading of the front cone, and hightened damping factor, but can anyone see any potential downside at midrange or higher frequencies of an acoustically and electrically in-phase driver a few inches behind the main driver?

Incidentally, there are plenty of ways to buy natural stone blocks online and they're not too pricey unless you go big. Panels for assembly are even cheaper (although I intend to mill the cabinets from single blocks for my project), so these things aren't really out of anyone's reach. You might have to indulge a stonemason with a rock saw and a reamer, but spend enough on the marble / granite raw materials and they might do this bit for you for free...

cheers,

Thinks: I wonder if three drivers in isobarik series would be pushing it...?


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PostPosted: 23 Jan 2009, 21:24 
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It shouldn't. In fact, it should actually help low distortion above Fs.

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PostPosted: 12 Feb 2009, 19:57 
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Joined: 18 Jan 2009, 17:35
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Hello Gents, I am now at the design stage and trying to determine how many drivers to use (2,3, or 4) before i start milling the rock cabs. For ease (and weight considerations), I'm going with the size of the original cabinet (16 cm x 12 cm x 24 cm [H x W x D]). If I have things right, the resonant frequency (fs) of this driver (130 Hz) will behave in the following way when wired in series in a sealed, isobarik (infinite baffle [-12 db / octave]) alignment:

1 driver = root 1 / 1 = 1 fs (130 Hz) -12db at 65 Hz 4 Ω
2 drivers = root 2 / 2 = .707 fs (92 Hz) -12db at 46 Hz 8 Ω
3 drivers = root 3 / 3 = .577 fs (75 Hz) -12db at 37.5 Hz 12 Ω
4 drivers = root 4 / 4 = .500 fs (65 Hz) -12db at 32.5 Hz 16 Ω (reasonable amplifier impedence cut-off)
5 drivers = root 5 / 5 = .447 fs (58 Hz) -12db at 29 Hz 20 Ω

If the power handling is 10 W per driver, does this increase when the drivers are multiplied in isobaric configuration (and wired in series), i.e., to 40 W for a 4-driver set-up? If not, then the reduced apparent sensitivity (in voltage terms) of the impedence reduction might make this unworkable if the 10 W power handling of the main driver remains unchanged (if wiring in parallel is necessary for higher power handling, the 4 Ω impedence quickly drops to insane levels with more than one driver).

I'm not looking for high level playback or a system for organ music; simply the best extension from a driver whose sound I already like from an enclosure of easily managable size. What about the wall loading effect (just driver output, assuming no cabinet-talk from an inch-thick solid granite cabinet)? The room reinforcement would be about 3 db / octave against one wall, no? I hope the intended three-driver configuration can be made to work...

cheers,
D


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PostPosted: 14 Feb 2009, 12:48 
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Hi davip,

This page does a nice job of explaining series connection for speakers and power handling

Let us know how you make out.
Cheers

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