[shogo33]

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.]

Re: IXL 18.2.2 - Project Advice Sought

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

 

[shogo33]

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.]

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.

 

[Mike P.]

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.

 

[a1161979]

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.]

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]

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! 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.]

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]

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

 

[Mike P.]

Reckhorn A-402 is 290 watts into 4 ohms. That won't power the sub to it's potential. The EP1500 would do nicely. It would provide a 5 db gain from 20 hz to 80 hz over the A-402. It doesn't have a subsonic filter so you'll need an add on unit set to 14 hz to protect the sub from over excursion at the lower frequencies. Reckhorn has a bass management system called the B1, an excellent unit for your needs. Over here it's about $100, not sure if it's available to you there or what the price might be. Check with whoever is selling the Reckhorn A-402, they may be able to supply it.

 

[db_bloke]

Shogo, I guess you're in OZ as you quote prices in A$, not sure if Syd / Mel or somewhere else. I managed to get my EP2500 for A$490 from djwarehouse in Melbourne, at the time the web price was A$510. Seems to be A$550 now and A$470 for the 1500, but as always they are negotiable. I'd give em a call and offer $500 or something. I think the extra headroom and lower distortion from pushing an amp less hard worth a few dollars. Not sure if the 2500 has more features as well..?
That said, this reckford amp (A$450) does have eq built in, but doesn't seem to have any balls. I'm still not sure what I'm going to do for EQ'ing my system. I might have a look round some other forums.

 

[shogo33]

G'day mate!
Melb guy from Mulgrave here! Thats the best price i've seen with an EP2500. Will give them a call today and try to haggle on something reasonable. Just a question though, as i've been following your build. Are you gonna run your sub in 4ohms bridged though (aka 2400w) from the EP2500? If so, isnt the overexcursion gonna be too high for the IXL 18? I've plotted the simulation via WinISD in a 120L sealed box using 2400w and anything below 45hz its pushing it over the 0.85 threshold incrementally. I'm assuming here that you are using the 30hz high pass filter setting on the amp to drop the curve and prevent overexcursion?

Yeah, if the Reckhorn had at least 750w then it would be ideal as it does have good EQ controls on it. Mike P did suggest a cheapish alternative to EQ, Reckhorn does make a standalone EQ unit called the B-1, but i havent seen it being sold over here, but i can drop an email to Darcher Audio, (who stocks Reckhorn) to see if they can order it in. It should set us back around A$200 i think.

Otherwise, maybe we can get the Behringer Feedback Destroyer whom most ppl on this forum uses for around the same price, circa $250. But it seems like a more complex unit to use and configure.

 

[db_bloke]

Hi, glad to help a fellow aussie on my price findings. I'm in Collingwood. I might look into the B1 unit.
The EP2500 puts out about 1900 real watts (see my other post), but there isn't a lot of difference between 1kw and 1900w, about 2db in theory. You need to square the input power to increase SPL by 3db and that's only in theory, real world is less as I understand it.

In answer to your QN, I plan to run the amp hopefully in stereo. I'll be giving each coil 800w or close to it at 20hz if I run it flat out. Did you see my other link on wiring subs (the 12 volt).

My sealed cube is 107l total (after speaker & bracing). I'm modeling with a LPF LWR at 40hz assuming I work out some kind of EQ (it might change).
With 1000w I get 22mm at 16.92hz, 111db 30hz, 107db 20hz!
With 1900w 30mm at around 17hz, 113db 30hz, 109db 20hz.
With 1600w I get 30mm at 10hz, 112db 30hz, 109db 20hz.
Not a huge difference, the figures look safe to me assuming you ignore xmax of 22mm. In practice though?

Hopefully 112db will do, although not THX, there is still room gain to add which can be up to 10db or so.
And yeah, potentially 120db at 20hz without room gain, that's quite loud.
I hope you have a brick house as you're going for a more adventurous design? Mine probably won't be worked on until after Christmas now, otherwise you could come round and have a listen.
Stuff really will rattle and the missus may kill you, I think the house should stay intact. I've only ever managed to loosen pictures from walls myself. IB systems look fun though :bigsmile:

 

[shogo33]

Ok. As much as I would love to build a ported design sub as planned, i'm gonna proceed with my original build with a sealed 107L design as recommended by WinISD. Reason is that i want to test to see if this would suit me better with consideration to the missus and neighbourhood. If i feel that its not loud enough, then i'll build a ported box next year. Also, as this is my first build and I currently only have a 12inch Dayton DVC with a PE 250w (bought from a kit 6 yrs ago from LSK) powered sub for music and HT, i know this build will be a major step up from my current sub :daydream:.

Got my order through to Bunnings and got a sheet of 2400mm x 1200mm x 1inch MDF. Got them to cut it so that I can build a 22 inch cube (similar to DB_Bloke's design.. thanks mate :bigsmile Will have to pick it up after work today. Cost is $56.80 plus $1 per cut, therefore I got quoted $75.

Also picked up some tools from there. These are cheapies and probably not the best, but they'll get the job done:
- Ryobi Single hand router ($90)
- MDF glue ($7)
- Router bits kit ($20)
- Clamps..clamps..clamps.. ouch! 6 x $30 ($180)
- Silicone sealant (to minimise air leakage) ($5)
- wood putty to fill in any gaps from mdf cuts ($5)
- veneer tape rolls (pine) 5 x $10 ($50)
- 1 IXL 8.2.2 driver ($349)
- 14 AWG speaker wire (1m) - $6
- Banana plugs speaker terminal ($8)

Total cost so far = $795. I havent bought the external amp yet but still considering either the EP1500 or EP2500. Crown and Peavey amps are out of my price range but with the Behringer unit, i'm still contemplating how loud the fan will be even after the fan mod. Assuming that the EP2500 is $550 + fan ($40), i'm looking at $1380 all up... Not bad for a DIY 18inch monster.. :R

I cant buy a commercial sub that will match this performance (simulated via WinISD) for under $3000 over here. I looked at the JL Fathom F113 here and the local retailer could do me a deal for $5600 for the unit and the SVS PB13 for $2849 + $150 shipping locally.

Overall, cant wait to get this baby cookin! Need to find my digital cam now..
But mostly, a big thank you to Mike P, Thxgoon, and db_bloke for your pointers and advice!

 

[Mike P.]

Looking forward to your build pics. :T Are you planning on equalizing the low end?

 

[shogo33]

I will be after Xmas or early next year, as funds are a bit tight atm. Mike, since i'm going with a sealed design, would you recommend using either a Behringer Feedback Destroyer (FBQ 2496) or the Ultragraph DEQ 1024? I can get the FBQ for $245 on sale and $270 for the DEQ.

For the moment, i was thinking of using the high pass cut off filter on the EP2500/EP1500 set at 30hz (i know i'll be taking a massive hit with low-end performance) but use this as an interim to avoid overexcursion on the low end with 2400w's of power in 4ohms.

Or alternatively(preferred), just hook up the sub to 1 channel on the amp (750w) and not worry about overexcursion with a sacrifice to db's.

No luck with the B-1 so far as the retailer says that he'll import them if there is a demand for them(ie: group buy etc).

 

[shogo33]

Just came across this plate amp by Elemental Designs, the LT range of plate amps, particularly the LT1300 and LT550. Are these any good in a sealed config? Controls seem to be very basic and no built in eq or subsonic filter and the specs pdf is a joke with minimal spec details..

 

[Mike P.]

The LT550 is a little shy on power for your application, especially if you will eventually boost the low end. The LT1300 is pretty well the same power as a EP1500. You'll do fine with either one. I modeled the IXL-18 in 107 liters, with 900 watts input power it produces 107 db at 20 hz and reaches Xmax at 14 hz. Try it out and see. If you need more low end then you can consider boosting the low end and adding a SSF.

As for which Behringer, here's a IXL-18 in a 24 inch cube sealed. Post #45 shows the before and after with the use of a FBQ-2496:

http://www.hometheatershack.com/for...irst-two-subs-help-post132882.html#post132882

 

[db_bloke]

Wow, I thought my Bunnings bill for like $150 or so was a lot. I managed to get some cheap clamps (well I thought they were still exe). You got a box of 2 for $26 and they go up to 760mm. They are pretty basic and look somewhat Russian. But I think they will work. I only got 4 though -total $53.
I may go a router, I'll cut out some circles on my offcuts and see how I go.