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Discussion Starter · #1 ·
100% dedicated HT sub. Plan is for ~7-8 ft^3 vented (roughly 24x24x36), one driver.

Looking at Dayton TIT400C Mk 3 (15") and the Mach Audio IXL 18.2.2, 500w plate amp (likely Oaudio BASH 500). Budget is $400-500 for the whole she-bang other than finish materials.

I've read several times here and elsewhere that the Mach is a "better" driver than the Dayton, and it is certainly more costly new. However, I may be able to buy a slightly used one for about the same price as the Dayton, shipped.

So, I modeled both drivers with the same amp in the same box, to see what differences showed up. Initially, WinISD put the Dayton in a 12 ft^3 box and the Mach in 7 ft^3, both with a tune of 19 hz, give or take. I reduced the enclosure size to 7 ft^3 since that is what I am shooting for, design-wise.

In the charts, the Mach is blue and the Dayton is yellow. From the model, there is essentially no difference between the two drivers if the boxes, tune, and amp is the same - less than 1 dB at most frequency points. My expectation would be that a pricier 18" driver would show some appreciable difference than a 15" driver - am I doing something wrong? I mean, 3" are 3", right? :)

Or are the differences more in construction, build quality, that sort of thing? In my case, price is a wash but if I was looking at new I don't see a reason to go with the Mach over the Dayton. :huh:

Final left-turn question - I've been looking at possibly building a THT rather than a large ported sub. There are a few reasons I've not committed; it sort of fits in the room, but not as well or seamlessly as a "normal" sub, and I've read things about it "falling off a cliff" after 20 hz. In the 7 ft^3, 19 hz design I modeled, response at 15 hz is 5-6 dB down from the 20 hz point - does this qualify as "falling off a cliff" :help:

I tend to think I'm starting to overanalyze this stuff, especially now that a THT-acceptable driver can be had for $80. That plus a cheaper amp requirement is starting to make this option pretty enticing. I may just go that route even though it will be a more difficult build (unless one of you fine folks talks me out of it!). At this point I have no sub, so pretty much anything will be an improvement, and worst case I can take the box apart and recycle some of the wood - for $250 in materials it is hard to resist!

I want to be :yikes: and :D and getting the :T from mah peeps, but I think I'm going :coocoo: because I'm :huh: and the more I read the more :dontknow: I get. I'm thinking I may need to stop the :ponder: and just get going, so I can :hsd: before I'm :eek:lddude:

Ya know whaddamean?
 

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Discussion Starter · #4 ·
Mike, I didn't apply a HPF as I was not sure what the parameters are for the Oaudio 500. I know it has parametric EQ and some sort of adjustable low frequency cutoff, but I wasn't sure how to model them. I figured any HPF would (should?) affect each driver equally but I'm getting the feeling you're going to tell me otherwise...

Side note - you are a saint for answering all of these "noob" questions so promptly and politely. I hope I can one day be in a position to give back to the community here.
 

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Discussion Starter · #6 ·
It looks like the OAudio 500watt has a subsonic filter that can be set to one of four settings: 12Hz, 16Hz, 20Hz, 25Hz.

Not sure how steep the roll off is though..
That's exactly what I was wondering - I went through all the documentation on the site but didn't find any specifics.
 

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I usually model a second order HPF it it's not stated. If it's really is a 3rd or 4th, your sub is safe. In this set up the 20 hz HPF would be best. It includes about 3 db of boost which can be cut with the EQ if required.

With 500 watts the output would be the same with therse two subs. The IXL-18 would use less cone excursion and has the potential for more output if you were to upgrade the amp in the future.
 

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Discussion Starter · #11 ·
I usually model a second order HPF it it's not stated. If it's really is a 3rd or 4th, your sub is safe. In this set up the 20 hz HPF would be best. It includes about 3 db of boost which can be cut with the EQ if required.

With 500 watts the output would be the same with therse two subs. The IXL-18 would use less cone excursion and has the potential for more output if you were to upgrade the amp in the future.
Thank you sir! That pretty much confirms what I was thinking after messing around with various configurations; in a reasonable sized box, with a 500w amp, these two drivers are essentially interchangable. I started seeing smoother response and deeper extension when I upped the amp and/or box, and when I changed the tune to very low levels. Which makes sense, since the Mach is a larger driver with almost identical excursion, so it is going to move more air and thus go deeper more easily.

Almost think I'm getting the hang of this stuff ;)
 

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Yep. Order of 2, with desired freq.

I could be wrong, but I believe that Q doesn't matter, since that's normally the width of the filter -- and in the case of a HPF, there's no real width. Just the frequency and the rate at which the lower frequencies roll off.
 
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