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-   -   New build: MKIII, RSS390HF or IXL driver (https://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/30671-new-build-mkiii-rss390hf-ixl-driver.html)

ironglen 07-06-10 09:52 AM

Re: New build: MKIII, RSS390HF or IXL driver
 

That crown amp could be bridged to 4Ω for a lone 15" or 18", or even to 2Ω for a pair of 12"s (though I'd have reservations running 2Ω). How much is an 18" IXL?

Doc 07-06-10 02:54 PM

Re: New build: MKIII, RSS390HF or IXL driver
 

Quote:

ironglen wrote: (Post 274752)
That crown amp could be bridged to 4Ω for a lone 15" or 18", or even to 2Ω for a pair of 12"s (though I'd have reservations running 2Ω).

Reading through the manual it appears that, if I am using only one speaker, I have to use bridged mode. That will increase the power to 700 watts, and I would run risk of bottoming out, if someone increases the amp to max. :spend::yikes: I like Crown amp, but with worries of someone increasing to max, I may go with plate amp.

Quote:

ironglen wrote: (Post 274752)
How much is an 18" IXL?

18" IXL is at $229, but out of stock. That is why I did not think of it. But now that you mentioned, I modeled it also. Surprisingly, it has absolutely no advantage over Titanic 15" or two CSS Trio 12". Actually SPL at 350 watts is a bit lower:huh:

This made me look at Malestrom too. Well, again big surprise, it is nearly identical (on WinISD) to Titanic and two Trio 12". It does have great advantage if I have huge enclosure i.e. IB system, and then I could get it down to 10 Hz relatively flat.

I am now settled on Titanic.

ironglen 07-06-10 03:34 PM

Re: New build: MKIII, RSS390HF or IXL driver
 

I was looking at your budget, and thought, well, the crown was kinda wasted on a single 15", and the ixl 18 is a good deal and could utilize that power (that's where the bigger drivers benefit). Plus, you have a good size room. Have you tried any sub in there yet to see what you get gain-wise? By going with the larger driver you'd get more headroom: always a good thing, especially for HT. Nothing at all wrong with the Titanic.

Doc 07-06-10 05:52 PM

Re: New build: MKIII, RSS390HF or IXL driver
 

ironglen, I agree with your point. That is why originally I thought of IB sub and external amp, with possibility of addition another one in future.

Unfortunately, the room has no carpet and has no sound dampening mechanism - whatever the carpet would provide. I had tried one movie several months ago, but I could get only hum from my then current sub-a capacitor is blown to ashes!- this sub will be my replacement sub.

mdrake 07-06-10 06:30 PM

Re: New build: MKIII, RSS390HF or IXL driver
 

That is a large room and for HT use you would be surprised how easy it is to over drive one 12 or even one 15. I think the suggestion to use an 18 is a sound one. I am not a big fan of Behringer (due to the their reverse engineering practices) but you could go with a Ficar Q18 and an EP-2500 and be just a tad over your budget.

Ficar Q18 = 300.00 + shipping
EP-2500 = 300.00 free shipping at some sites

Matt

Doc 07-06-10 07:30 PM

Re: New build: MKIII, RSS390HF or IXL driver
 

Quote:

mdrake wrote: (Post 274890)
That is a large room and for HT use you would be surprised how easy it is to over drive one 12 or even one 15. I think the suggestion to use an 18 is a sound one. I am not a big fan of Behringer (due to the their reverse engineering practices) but you could go with a Ficar Q18 and an EP-2500 and be just a tad over your budget.

Ficar Q18 = 300.00 + shipping
EP-2500 = 300.00 free shipping at some sites

Matt

Hmmm, back to drawing board. I can not model this sub --- If I enter the values WinISD has problem with it, and if it is allowed to autocalculate many of the values, they are substantially different than Fi website supplied values. I guess, I should think of two 15 inch or possibly two 12 inch subs. Would it be better to build two separate boxes each housing one 12 inch sub as opposed to putting both in one larger box?

ironglen 07-06-10 10:32 PM

Re: New build: MKIII, RSS390HF or IXL driver
 

A big box uses less wood and can get heavy, while twin boxes allow placement flexibility and ease to move. I think it depends on your placement ideas.

Too bad on the IXL: I know Mike P has been pleased with his Mach 5 drivers, and they're well priced. No idea when available? I'm with Drake on the displacement opinion: it's costly to upgrade drivers/enclosures in money and time. You might spend a bit more on the driver and keep a keen eye on used/b-stock amps as they're solid state should be a relatively safe purchase as far as used goes. You could still make your budget that way...

Doc 07-07-10 07:01 PM

Re: New build: MKIII, RSS390HF or IXL driver
 

I am planning to create this "box" under the screen area. I am planning to permanently fix it there, using the framing structure on top, back and floor board, thus with built in bracings! I may be able to get away with just one 3/4" MDF sheet in these walls, with other "open" and non braced walls of the box using two layers of 3/4" MDF. If it is a large box, it will sit in the middle, if two small boxes, I can keep on each sides and use another built in braced side.

All in all, either way, I do not have to worry about the weight of the box - I am not moving it, looks of the box - only the front will need to be decent, or wood needed - as I have more than enough MDF sitting around for this project.

As doubling the sound means raising SPL by 6 db, I may get more effects from two boxes than placing two drivers in one. I do not have any experience to test that theory though.

ironglen 07-07-10 08:50 PM

Re: New build: MKIII, RSS390HF or IXL driver
 

You'll have to combine the volume for two drivers in a single box, but you'll obtain the same output as separate boxes. The smaller boxes would use smaller pieces, and thus require less bracing to reduce resonance; so it's really up to you. My advice is don't tune below 20hz unless you have an 18", use a hpf, and get the best drivers you can afford (xmax). That way you'll have increased headroom since you have a nice sized room. Post pics of the process too!

mdrake 07-07-10 09:38 PM

Re: New build: MKIII, RSS390HF or IXL driver
 

Quote:

Doc wrote: (Post 275166)
I am planning to create this "box" under the screen area. I am planning to permanently fix it there, using the framing structure on top, back and floor board, thus with built in bracings! I may be able to get away with just one 3/4" MDF sheet in these walls, with other "open" and non braced walls of the box using two layers of 3/4" MDF. If it is a large box, it will sit in the middle, if two small boxes, I can keep on each sides and use another built in braced side.

All in all, either way, I do not have to worry about the weight of the box - I am not moving it, looks of the box - only the front will need to be decent, or wood needed - as I have more than enough MDF sitting around for this project.

As doubling the sound means raising SPL by 6 db, I may get more effects from two boxes than placing two drivers in one. I do not have any experience to test that theory though.

The other thing to consider is the fact that your chosen location has no corner loading, not that this is necessarily a bad thing but I thought I should mention it as you will not get the gain from corner loading.
I have my sub under my stage and a little over a foot from the corner and it still has plenty of gain.

I hate even typing this as I feel like a total geek but I found the rule on Google so......
Coupling will occur when the frequency is such that the center-to-center distance between the two woofer manifolds is less than one-half wavelength so at 80 hz that would be 7ft. As long as you place your drivers close enougth together you will gain the extra db using two drivers but you could do almost the same thing by going to one 18 vs. one 15. :bigsmile:


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