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-   -   IXL-18.2.2 Sealed (https://www.hometheatershack.com/forums/sealed-subwoofer-build-projects/14923-ixl-18-2-2-sealed.html)

shogo33 12-08-08 07:38 PM

IXL-18.2.2 Sealed
 

Hi guys,

I'm doing a sealed 200L box using the Mach5 IXL 18.2.2 driver. Just ordered the IXL 18.2.2 driver and i've been reading so much on this forum about DIY and how much fun you guys are having with it. I'm doing this simply to build a great sub whilst keeping the cost low (cant afford those $3000+ subs over here, as my team have been told that we aint getting no Xmas bonus for the year due to the "economic crisis"!)

With my build, using the IXL 18 and a sealed 200L with a Q.707 alignment in WinISD Pro, seems good all for the exception of the cone excursion issue when i apply the use of 2400w (planning on using the EP2500 with it), the estimation says the overexcursion occurs at 38.67hz at 0.866 peak. I'm new to this so i might be doing this wrong in WinISD pro. I've downloaded the pro file from the link and am using it to calc a sealed enclosure suitable for the IXL 18.

I submit to your knowledge and expertise to here for guidance. Thanks in advance! :)

Mike P. 12-08-08 07:58 PM

Re: IXL 18.2.2 - Project Advice Sought
 

Welcome, Shank! What will you be using the sub for? HT, music or both?




shogo33 12-08-08 08:39 PM

Re: IXL 18.2.2 - Project Advice Sought
 

Thanks Mike.
It will be predominantly for HT, say 70% HT and 30% music and it cant be too big or the missus will have a fit, like 300+ litre sized cabinet, which is why i chose a sealed design around 200L. Room size is around 10 feet wide x 20 feet deep and 8 feet high, if this helps.
cheers

Mike P. 12-09-08 03:20 AM

Re: IXL-18.2.2 Sealed
 

1 Attachment(s)
The power handling of the IXL-18 is 1000 watts. At 700 watts input cone excursion is exceeded at 20 hz. The use of a SSF is required at 14 hz to protect the sub from over excursion below 20 hz for HT use. If you were to apply 1000 watts to the sub, a SSF would be needed at 19 hz. With 700 watts input and a SSF at 14 hz you get more low end output compared to the other. Here's a SPL graph of the 2 models with the stated power input and subsonic filters applied. Both models assume you won't be boosting the low end, if you do, it changes everything.

Attachment 10704




Mike P. 12-09-08 03:32 AM

Re: IXL-18.2.2 Sealed
 

1 Attachment(s)
Since you stated this will be predominantly for HT, you should consider ported. It's very doable in 200 liters. Tuned to 20 hz with a 8 inch port 42 inches long, it will handle a full 1000 watts with a SSF applied at 15 hz. Here is the model compared to the sealed. Big gains in the low end.

Attachment 10705




a1161979 12-09-08 08:16 AM

Re: IXL-18.2.2 Sealed
 

Why 200L sealed? When i model it using the downloadable file here i get a 100L enclosure with a Q of .7, some thing must be wrong :dunno: 200L seems way to large... Also Mike i thought the IXL could handle more travel than 22mm, i realise the rated Xmax is 22mm but cant the speaker handle 30mm of travel before the suspension bottoms or is this Internet myth?

Mike P. 12-09-08 10:47 AM

Re: IXL-18.2.2 Sealed
 

200 liters is a bit big for a sealed IXL-18. The recommended size by Mach 5 is 130 liters and it does model better. Since Shank stated he has 200 liters, we'll see if he will consider ported with that size.

As for Xmax, exceeding it increases distortion in most cases. Going past it a bit won't hurt, but trying to find the mechanical limits of a sub is looking for trouble in my opinion. The same goes for power handling. Staying within the stated limits of the manufacturer ensures years of trouble free operation.




shogo33 12-09-08 03:58 PM

Re: IXL-18.2.2 Sealed
 

Hi All,

Thanks for the pointers Mike. I've looked at the graph's you've modelled earlier for the 200L ported tuned to 20hz that shows the yield gained in the lower regions makes more sense for HT. Also taking into account the max power of the driver of 1000w, what do you guys think of this?

Ported 200L's cabinet tuned to 19hz using 3 "4" inch ports at 11 inches each and powered by the OAudio 500w Bash amp and applying the subsonic filter to 12hz?

My reasoning for this is that:
1. Local hardware store dont have 8 inch PVC pipes. Only 6 & 4 inch PVC in stock.
2. OAudio plate amp has a subsonic filter at 12,16,20,25hz settings along with adjustable parametric EQ from the range 20hz - 80hz.

Also, an unexpected benefit during a discussion with the misus yesterday, she was willing to compromise moving the old coffee table out, so i'm no longer restricted to a max of 200L box but was told to keep it 'reasonable' for the sake of aesthetics in the room.

Just a couple of questions. Looking at the "group delay" graph, with the design above, at 20hz, the delay increases exponentially in the lower regions. Is it acceptable to have the delay around 38ms at 19hz, with a max of 43ms at 13hz? Is it going to be noticable, ie: not producing a tight sound? I havent heard a subwoofer that can go that low, so this is all a new experience..

Also, with port resonance of this design, with 3x 4 inch ports tuned to 19hz at 11inches each, the resonance is rated at 178hz. Is this ok?

Also, does it make much of a difference tuning it to 19hz as opposed to 20hz in this ported design?

Thanks heaps for the help so far, i think i'm starting to slowly see how the sum of the whole specs impacts the design of the subwoofer! :D In the meantime, i'll call around to ask if any of the local hardware stores have any 8inch PVC pipes in stock. Btw, just as a precaution, is it ok to use an 8inch sonotube (formatube as its called here) as an alternative?

Mike P. 12-10-08 07:09 AM

Re: IXL-18.2.2 Sealed
 

A couple of things to note. The OAudio 500w Bash amp would not be a good choice for this setup. The amp also applies boost at the SSF frequencies. The amp would benefit a design where the response curve rolls off sharply below 25 hz and the boost would help achieve a flatter response. That's not the case with this setup and the boost would create a peak in the low end response.

Tuning 200 liters to 19 hz requires three 4 inch tubes 37 inches long each, not 11 inches. 8 inch sonotube (formatube) is a popular choice for large port tubes. A slot port with the same amount of surface area would also work. Remember that the volume taken up by the ports, bracing and sub have to be subtracted so the net volume of the cabinet is 200 liters.




shogo33 12-11-08 05:14 AM

Re: IXL-18.2.2 Sealed
 

Bummer! Was rather keen on the OAudio 500 amp. After what you've said, it seems that the OAudio plate is more suited to a sealed config rather than ported.

Since the max power rating of the sub is 1000w, what suggestions would you recommend to use with this build? Amps that I can easily source locally are:
- Reckhorn A-402 (A$450)
- EP1500 (A$500)
- EP2500 (A$600)

cheers


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