Woofer to suit Coral Flat10ii - diyAudio
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Old 3rd August 2009, 02:14 AM   #1
lazyfly is offline lazyfly  Australia
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Join Date: Jun 2004
Location: Melbourne
Default Woofer to suit Coral Flat10ii

Hi folks,

I'm at a loss.

I have a pair of lovely Coral Flat10ii's. A 60L test cab tuned to 44Hz was built and the sound, certainly the upper bass, mids, upper mi - ahh hell, from about 100Hz to around 8k they sound awesome. Beautiful even.

The bass rolls off pretty quickly in the test cab from perhaps mid 50's (F3). It's a very nice bass tonally but a bit lazy too. Instead of making larger cabinets to get a lower F3 and probably killing the drivers I'd like to build a cabinet with the Corals in a sealed of approx. 20L. With a 10 or 12" woofer filling in down below (preferably sealed also).

Modelling the Coral in Uni-Box shows a smooth roll-off from 200Hz with an F3 of around 112Hz. I've played around modelling with SB Acoustics 12" woofer in ~60L sealed which appears to cover the lowest bass notes (F3 ~40Hz). This would require plate amps to get the required gain, but that's okay. I've modelled other woofers too, but there's just too many of them.

I'm wondering what others would do as I'm stumped as to which way to go. There is of course PA drivers but so many of them too!

What to do... what would you do?

T/S of Coral - supplied by Kim Bond. Thanks Kim
Re: 7.7 Ohm
Fs: 36.6 Hz
Vas: 141 L
Qms: 3.9
Qes: .319
Qts: .295
Eff: 2.2 %
Sd: 360 sq/cm
Mms: 23 g
Mmd: 15.8 g
Cms .000823 m/N
Bl: 10.8 T/m
SPL 96dB (1W/1M)
Xmax: 2 mm

Thank you for any suggestions!
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Old 1st September 2009, 03:06 PM   #2
tuyen is offline tuyen  Australia
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Hi there. I just purchased a pair of Coral Flat 10 II too. I'm going to fit them into the BLH cabinets designed for the BETA 10. Hopefully they still sound good with them. You mention the flats only sound good til 8k.. what happens to the rest of the high freq??

I also purchased 2 Coral 12" 12L-27A woofers (freq resp. 25-800hz). They will be fitted in separate sealed boxes and I will run them off a subwoofer plate amp and adjust the crossover so it blends in nicely. I'm guessing it will be around 40-60hz? Maybe get a reckhorn A402 later on when funds permit.

I'm located in Australia too
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Old 1st September 2009, 05:32 PM   #3
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Location: UK
Hmm. Those specs. don't completely gel. Working on the assumption that Bl is the more accurate, then Vas will be somewhat higher than indicated here; ~165.44 litres.

Anyway, based on those specs. (adjusted) then a Vp = Vas MLTL would work pretty well with the Corals alone, although it's a v. big box,

L= 48in
CSA = 210in^2
Zd = 19.75in
Zp = 45in
Vent = 6in diameter x 1.25in long. Line top back & one sidewall with 1in acoustic fibreglas & adjust this & vent tuning to taste from there as it's a max-flat alignment. Doesn't have massive headroom, but better than some; total displacement stays below 1mm 1m/1w.

If you wanted to go multiway, you'd probably do worse than something from the Eminence line -if possible, go for a 15in model. Beta 15, one of the Deltas or Gammas etc. Whatever takes your fancy really; they're all pretty good for the money. Get them in a suitable vented box & the Coral on a small baffle, cross them at about 200Hz or 500Hz depending on what you're after & you've got your own Basszilla clone that'll blow most commercial gear out of the water.
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File Type: gif Flat10II MLTL.GIF (5.7 KB, 92 views)
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Old 6th September 2009, 09:35 PM   #4
lazyfly is offline lazyfly  Australia
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Join Date: Jun 2004
Location: Melbourne
Hi tuyen,

Good buy! Have you had a listen yet? I've read on several occasions where they've been placed in the Beta10 BLH. I haven't actually read any results though - not even listening impressions.

After ~8k the top end rolls off fairly quickly and is not terribly convincing - cymbals are more 'shhh' than 'tsss'. It really does miss the last octave. I could live with it but prefer not too. An old Foster horn tweeter (Radioshack?) picks up the slack and adds a lovely non-intrusive sparkle.

Coincidentally I've just tried them in 12L (what I had already) sealed cabs with an F3 approx. 125Hz, sitting atop a 10" woofer using a plate amp crossed approx 120Hz. They REALLY came to life not having to deal with anything down low. Very focused and perhaps too forward. It may be worth a slightly larger box for lower Qtc or have I got that back to front?

Those 12's should blend beautifully as the Response carbon-fibre woofers work extremely well, better than expected.

Scott, Thank you. I appreciate the effort gone into your reply. You've just stated two methods I've been interested in for some time. MLTL because I'd like to hear what it does with bass vs. vented. Originally I was worried with cabinet size but have since gotten over it. It'll be made as big as it needs to be. The two arguments for this driver are a: It's a waste having a 10" driver not doing bass, b: it's a waste destroying the driver in a moment of blissful volume abuse (easy to do, you want to turn them up!)

Then there's the BassZilla OB version. There's not enough space in the listening room to pull the speakers out more than about 2 feet though. Perhaps some damping material draped over the rear of the driver would work? It's easy enough to try.

Thanks Scott, I've got some things to think about
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