DIY FLH...or not? - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #11 of 29 Old 03-22-16, 09:53 PM
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Re: DIY FLH...or not?

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Not going well so far.

I can identify with that for sure. Good luck! Let us know how it go.


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post #12 of 29 Old 03-29-16, 08:41 PM Thread Starter
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Re: DIY FLH...or not?

I am thinking about a 15" down firing Dayton Classic 15" (DCS380) in a 12 cuft box tuned to 18Hz next to the couch. Winisd is showing max excursion at only about 100w when the sub is rated for 250w. Does this seem right? The specs show the max excursion at .33". On one hand, it is nice to be able to use the sub to its full potential with a smaller amp...but I feel like I should be using a larger amp since the sub is rated for it.
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post #13 of 29 Old 03-29-16, 11:55 PM
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Re: DIY FLH...or not?

If you're planning on using that "A" space for a table anyway, you could possibly kill two birds with one stone by either 1) building the box big enough to work as the table (and dampen/isolate the table surface somehow) or 2) build the box just small enough to completely fit inside the footprint of the table so it is "hidden".

Horns are awesome because of the high sensitivity... and they're a pain because of the high sensitivity. Have you taken a look at the THT and THTLP designs from Bill Fitzmaurice? He's got some stuff on his website that, while not the simplest of designs to execute, are very flexible in terms of driver selection and finished size. You said you had the equipment and the experience to pull off a complex design, so it might well be worth looking into.

As Jman said, horns can be very finicky about placement and direction. The difficult part of this dilemma is that what you really want to do is test it in the room... which you can't do without building a horn.

Another option in a different direction is to go LLT (Large Low-Tune) vented. These boxes have the advantage of providing very deep extension (into the teens in Hz) while maintaining reasonable linearity. The disadvantage is that they're typically power-hungry because they need fairly robust drivers to deal with the rigors of operating in those ranges within the parameters of a vented orientation. Horns can perform similarly with less power.
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post #14 of 29 Old 03-31-16, 07:05 PM Thread Starter
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Re: DIY FLH...or not?

I am planning on a Dayton classic 15" with a Bosch 300w amp in a 12cuft box tuned to 18Hz with the driver and port down-facing. I will put a marble top on it with gel vibration pads under it. I am going to go with the classic 15" for now and if I blow it up I will step up to the Ultimax driver.
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post #15 of 29 Old 03-31-16, 07:13 PM
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Re: DIY FLH...or not?

Why not just do the UM driver to start with?


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post #16 of 29 Old 04-01-16, 06:35 PM
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Re: DIY FLH...or not?

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Why not just do the UM driver to start with?


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Proof of Concept. Build it cheap first... and if it works well, replace the cheap parts with better ones later. Same approach I'm currently using for my IB setup. I've got 4 GRS 12" subs that cost me a total of $80. The specs lined up nicely with what I needed. I'll switch the the UM 12" eventually when don't mind dropping $600 on new drivers, because those are much better in terms of frequency response and air displacement and they still fit my specs.

to OP: Make sure those two drivers will perform similarly in that orientation. Granted, LLT setups offer a little more leeway than something like a minimum-volume acoustic suspension box... but you don't want any nasty surprises.
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post #17 of 29 Old 04-01-16, 06:38 PM
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Re: DIY FLH...or not?

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clint357 wrote: View Post
I am planning on a Dayton classic 15" with a Bosch 300w amp in a 12cuft box tuned to 18Hz with the driver and port down-facing. I will put a marble top on it with gel vibration pads under it. I am going to go with the classic 15" for now and if I blow it up I will step up to the Ultimax driver.

If you REALLY want to dampen vibration from the box into the marble top (which will probably look very nice, btw), go with magnetic levitation. A few strategically placed rare-earth magnets and some padded corner bumpers will give you the coolest floating stone table top ever!
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post #18 of 29 Old 04-01-16, 07:32 PM
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Re: DIY FLH...or not?

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Proof of Concept. Build it cheap first... and if it works well, replace the cheap parts with better ones later. Same approach I'm currently using for my IB setup. I've got 4 GRS 12" subs that cost me a total of $80. The specs lined up nicely with what I needed. I'll switch the the UM 12" eventually when don't mind dropping $600 on new drivers, because those are much better in terms of frequency response and air displacement and they still fit my specs.



That's perfectly reasonable. I was just thinking measure twice, cut once.


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post #19 of 29 Old 04-01-16, 08:31 PM
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Re: DIY FLH...or not?

As long as the parameters of the drives in question are pretty similar, he should just be able to drop the new one in place and be good to go.

OP, it might be worth your while to make a removable baffle plate when you prototype. Then you can make a new baffle for the new driver and not have to worry about silly details like mounting holes lining up, or having too much (or too little) play in the cut-out. Once you're satisfied it will work, and you're ready to swap (or you set the Classic on fire, or whatever) you just pull out the whole baffle and drop the new one in place with the driver already mounted. It will take a lot of the headache out of the upgrade.

AND, if you have a levitating top, you won't have to deal with the extra weight when you try to flip it over.
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post #20 of 29 Old 04-01-16, 08:36 PM
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Re: DIY FLH...or not?

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As long as the parameters of the drives in question are pretty similar, he should just be able to drop the new one in place and be good to go.


That's what I mean. If the parameters line up, and the modeling is the same, why waste the money on the junk driver in the first place.



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