Planning my 1st DIY build, need a sanity check and advice - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 14 Old 01-18-12, 09:52 PM Thread Starter
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Planning my 1st DIY build, need a sanity check and advice

Hi, I have been reading the DIY subwoofer forums for a while and wanted to ask if I am on the right track so far. I am considering a DIY build for our living room HT, which is part of a large, open floor plan. Here is the first floor: http://pl.an/mg9lyp. This area also opens up to the second floor via a stairwell and a large foyer with an open balcony. I estimate that the entire volume is > 5,000 cubic feet. Our usage is varied, and these would be on for all activities; our split is around 45% TV, 35% movies, and 20% music. I've never had a sealed sub at home, but I've previously preferred sealed subs for car audio. I don't know my exact budget yet as it will depend on bonus and income tax refund size, but I'm hoping to have $1,000 - $1,500 to work with. I currently use a Boston Acoustics PV700, which has a 12" driver, vented, with a 200 watt amp. It sounds pretty decent, but even corner loaded and with near field placement, I can barely hear it below ~30 Hz.

Placement options are limited to either side of the TV stand. To maximize internal volume I expect to use these as speaker stands for my Ascend 340SEs. I would also like to minimize cabinet vibrations, so I've been thinking about dual opposed drivers in a pair of braced, sealed, passive cabinet. I like the idea of isolation pads under the Ascends, but after watching videos of Epik Empires, will they be necessary? For each enclosure, the max height is 24" (minus any foam), max depth is 24", absolute max width is 48" but I would like to stay well under this if possible. Considering ¾" MDF and doubling it up on both baffles, if I calculated right this should give me between 6.15 and 12.71 ft³ to work with, minus bracing and driver displacement.

Should I be looking at dual 15s, dual 18s, or something else in each box? Is this plan going to work well for the large room? I keep hearing that ported subs typically work better for open floor plans, but is this only because of the extra output around tuning frequency? I *think* I would prefer to have the extension for movies, if it's reasonable to expect usable output down low in our room without huge amounts of power and adding dedicated circuits for monster amps. One option I've considered is building a pair of 24" cubes, each with a pair of Dayton RSS390HFs wired in parallel for a 2 Ω stereo load to an EP4000 (EQ'd by miniDSP). I could always add another pair down the road if needed. I am also open to the idea of ported subs if they will work better for us!

I do have several tools that I can use for the build, including a router. I don't have a chop saw or table saw, and I also don't have very good wood working skills but I do enjoy these types of learning projects. Since this is going in our living room, the cabinets can't be terribly ugly. I'll try to match the finish of the Ascends, and go for basic flat black paint. I'm thinking that I will try the build myself first, and if I fail miserably I will hire a local custom cabinet builder and swap the drivers.

Well, this turned into a huge post. Sorry for the wall of text! Thank you for reviewing, and thanks for your help!
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post #2 of 14 Old 01-19-12, 12:53 AM
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Re: Planning my 1st DIY build, need a sanity check and advice

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Should I be looking at dual 15s, dual 18s, or something else in each box? Is this plan going to work well for the large room?
I think a single UXL-18 per box, sealed, or a W15GTI per box, vented or passive radiators, will do the job - so duals will be just deadly but make sure not to stuff drivers in too small a box.

I also think you're going to want to invest in some measurement gear to get an idea of what's ACTUALLY going on rather than wasting your time guessing.

Quote:
I keep hearing that ported subs typically work better for open floor plans, but is this only because of the extra output around tuning frequency? I *think* I would prefer to have the extension for movies, if it's reasonable to expect usable output down low in our room without huge amounts of power and adding dedicated circuits for monster amps.
Essentially, yes. Don't put too much stock into differences in sound between alignments... figure out how it works with the room for flattest response.

The more drivers, the better though.

Don't underestimate us! Whether it be time, space, or alternate realities, they mean nothing to us! We will pierce the path and methods you've chosen! That is who we are!
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post #3 of 14 Old 01-19-12, 02:38 AM Thread Starter
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Re: Planning my 1st DIY build, need a sanity check and advice

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GranteedEV wrote: View Post
I think a single UXL-18 per box, sealed, or a W15GTI per box, vented or passive radiators, will do the job - so duals will be just deadly but make sure not to stuff drivers in too small a box.

I also think you're going to want to invest in some measurement gear to get an idea of what's ACTUALLY going on rather than wasting your time guessing.
I just did some reading and those UXL-18s do look very interesting! I downloaded the WinISD file and will play with some sealed and vented models.

I have a Radio Shack analog SPL meter and REW, but have only used it to help with positioning my current sub. I may have to budget for a calibrated mic (+ REW) to use with the new subs.

Quote:
GranteedEV wrote: View Post
Essentially, yes. Don't put too much stock into differences in sound between alignments... figure out how it works with the room for flattest response.

The more drivers, the better though.
How can I measure my room's response? Will the RS meter get the job done? Do I just take a few sweeps in-room, then more outdoors, with the meter at a fixed distances?
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post #4 of 14 Old 01-19-12, 10:12 AM
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Re: Planning my 1st DIY build, need a sanity check and advice

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ls1_sounds wrote: View Post
I have a Radio Shack analog SPL meter and REW, but have only used it to help with positioning my current sub. I may have to budget for a calibrated mic (+ REW) to use with the new subs.


How can I measure my room's response? Will the RS meter get the job done? Do I just take a few sweeps in-room, then more outdoors, with the meter at a fixed distances?
I would recommend getting a cross spectrum calibrated mic and preamp. SPL meter plots are akin to very smoothed measurements so they won't accurately represent your hearing. useful for setup but less so for really maximizing/understanding things like punch and extension.

Don't underestimate us! Whether it be time, space, or alternate realities, they mean nothing to us! We will pierce the path and methods you've chosen! That is who we are!
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post #5 of 14 Old 01-19-12, 10:54 AM
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Re: Planning my 1st DIY build, need a sanity check and advice

I'm like you in that my woodworking skills are a bit shy, so I just finished my first "assembly" by using a pre-made cab from Parts Express. I chose the 3 foot cube in black, and was pleasantly surprised by the quality of the cab; not as completely braced as I would like but very nice for the money, and certainly better than I could do as a first effort. You might also check out the pre-fabs from Madisound or diysoundgroup. I used a RSS315HF in a sealed alignment, lined and stuffed the box to achieve Qtc of about .69. It sounds great in my room, which is very different from yours. PE offers spare blank baffles for their cabs, so as a further experiment for my ears, I intend to switch the driver to the 390HF, to hear and measure what the different "Q" sounds like; that way in future, I'll have better experience in designing to my taste. I intend to build my own cab at some point, but not until I've studied and heard as many different designs as I can, because really I'm after DIY sound, not carpentry. Anyway, my point is that there are pre-made boxes out there that you can play with...
G'luck,
Tom
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post #6 of 14 Old 01-19-12, 11:11 AM Thread Starter
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Re: Planning my 1st DIY build, need a sanity check and advice

Thanks for the responses! Do you know some good links where I can brush up on the different driver parameters? I have been trying to use WinISD, but don't really understand what each of the values mean that I am entering. This also applies to Qtc.

GranteedEV, I downloaded the PDF from your signature and will try to absorb it over the weekend.
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post #7 of 14 Old 01-19-12, 11:45 AM
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Re: Planning my 1st DIY build, need a sanity check and advice

There's a sticky here: http://www.hometheatershack.com/foru...arameters.html which gives you some ideas; also a tutorial on WinISD which I found very valuable: http://www.hometheatershack.com/foru...inisd-pro.html.
To really get edumacated, I'm reading Alden's "Speaker Building 201" which I'm finding to be the best resource. I plan on following it with Dickason's "Loudspeaker Design Cookbook." Both are available from PE for less than I paid. SB201 defines what each parameter is, how it's important and what it's used for, what the formulas are and how the variables relate, and how different design decisions are made. I recommend it highly.
Tom

Edit: No, I don't work for PE; they just happen to sell some stuff I've been using.

Last edited by tshifrin; 01-19-12 at 11:50 AM. Reason: Disclaimer
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post #8 of 14 Old 01-22-12, 03:33 AM
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Re: Planning my 1st DIY build, need a sanity check and advice

GranteedEV made some great suggestions.

Mic will be your best friend along with REW/MiniDsp.

Going from your current subwoofer to a pair of UXL's or even dual opposed RSS390HF's from Dayton will be an amazing improvement.

Either way building a sealed cabinet is simple. And either sub will get the walls rattling.

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post #9 of 14 Old 01-22-12, 04:12 PM Thread Starter
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Re: Planning my 1st DIY build, need a sanity check and advice

Based on the price and availability I am also interested in the Fi SSD18, but I don't know much about the different options that they offer. Price ranges from $254 to $324, for no options to fully optioned. Any thoughts on this driver vs. the Mach UXL-18?

I also have a question regarding amps to drive a pair of ported 18s. The ratings are 1,200 and 1,000 watts RMS for the UXL-18 and SSD18, respectively. Would a Behringer iNuke6000DSP be a good choice, or possibly a Marathon MA-5050? Or is there a better option to consider?
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post #10 of 14 Old 01-22-12, 06:51 PM
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Re: Planning my 1st DIY build, need a sanity check and advice

IN regards to amps the Marathon is a good amp but I have never heard anything good about customer service on that brand. They are powerful though.

As long as you have EQ you would be fine with any of the options for the SSD drivers. I used to have a pair of 15 SSD's with the BP/cooling option.

When I design my subwoofers I usually try and buy an amp that can deliver at least 2x's the rated rms power. But by going with a smaller amp you will only be amp limiting instead of driver limited for output. Which being amp limited would be better if you are not careful with your EQ.

I have never used the Inukeamp so I can not comment on that. I do know that the EP2500 has been a stable amp to use for subs so I would think the Inuke should be fine. Only time will tell.

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