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First HT DIY Subwoofer for a noob on a budget..

31691 Views 99 Replies 7 Participants Last post by  jeffrobinson
Good evening gentlemen,
I'm a noob who bought a pair of Phoenix Gold Ti15d's from Sonic years ago planning to stuff them in a suv. Fast forward 9 years, they were never installed. Want to build a home theater sub for the kid and I need the right box the first time due to a state employee budget. Picked up a Bash 300w amp at partsexpress for one Benjamin. Phoenix recommended a sealed 1.5ft for sq, or a 3.5ft ported w two 4x9.75in ports. Are these still the best choices? Those were speced for car use and that was a long time ago. I have bassbox pro 6 and cant figure it out. Everybody says go low for home theater and I'm stumped. Anybody up for a little bench racing? Specs are:
Fs: 26.21HZ
Re: 1.75 Ohms
Qms: 9.26
Qes: 0.594
Qts: 0.558
Vas: 114.63 liters
Mms: 283.15 grams
Cms: 130uM/Newton
BL: 10.89 Telsa-m
SPL(1w/1m): 88 db
Sd: 792 sq cm
Xmax(field): 36.2mm p-p
Size of enclosure is dosent matter, its in my living room. I want low, right? My front mains go to 65hz, receiver is Yamaha with YPAO room eq, room is 15 by 20 or so with 12ft ceilings and hardwood floors. Use will be 95% movies, 5% metal. Anybody feeling like helping out?:huh: Thank yall in advance, Jeff.
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Nevermind MikeP, unless you see a problem with this design. Including the bracing spec'd already, and the driver, this is my final design.
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My laminate came in! Woohoo! Maybe I can grab a pic or two of it, and my exsisting tv stand that I'm trying to match with this sub build, and show it to yall fairly soon. Course that means I'm gonna get picked on for a multitude of home theater sins. Bright colored paint, white trim, speakers too close to the floor, cats, kids, etc...:rolleyesno:
You're gonna get picked on a lot more than that if you don't post pics of your build process. :bigsmile:
I know! And I will. When I'm finally done with the subs, I have another thing thats been eating at me like crazy. Wrinkles in my 120" motorized screen. Causes the ticker line on ESPN to make me seasick!!! ARGH!:explode:
MikeP, we briefly touched on future-proofing and a replacement driver that would be a good affordable match if these old PG's gave up. I've been trolling around the net and came up with the Dayton Audio DVC385-88 15" DVC Series Subwoofer. Do you have a suggestion for me? This Dayton seems to be consistently getting modeled at 6ft^3 @ 20hz, but nobody is backing it up with a WinIsd graph like you do. If I stuck this in the box we have been planning (6ft^3 @ 20hz), and powered it with the Bash 300, what would I be looking at?

Power Handling (RMS)
350 Watts
Power Handling (max)
700 Watts
8+8 ohms
Frequency Response
20 to 450 Hz
90 dB 1W/1m
Voice Coil Diameter
Magnet Weight
112 oz.
Resonant Frequency (Fs)
19 Hz
DC Resistance (Re)
2.8 ohms
Voice Coil Inductance (Le)
1.82 mH
Mechanical Q (Qms)
Electromagnetic Q (Qes)
Total Q (Qts)
Compliance Equivalent Volume (Vas)
8.20 ft.³
Mechanical Compliance of Suspension (Cms)
0.24 mm/N
BL Product (BL)
16 Tm
Diaphragm Mass Inc. Airload (Mms)
Maximum Linear Excursion (Xmax)
15.1 mm
Surface Area of Cone (Sd)
829.6 cm²
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Lame, I know. But here is a little pic of a sub and the very heavy roll of laminate pieces.
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Your port dimensions guarantee that the cabinet is future proof.

Yellow is the Phoenix Gold with a Bash 300.

Orange is the DVC385-88 with a Bash 300.

Green is a SI HT15 with a Dayton SA1000.

Oscilloscope Slope Text Line Technology
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Wow, my PG's look a little limp!! I guess I'll call it "room for growth." Thank you, yet again, for your efforts. How many other guys are you working with, just like me?
I work with whoever comes along and needs help. My post count says it all!
A little update. The $99 Bash 300 sale ended at parts express ended before I made a final amp decision. So I decided..and picked up a second NIB Bash 300 on ebay for $125. Price you pay for indecision. I find myself lusting after those Dayton DVC385-88s. While looking at your chart, MikeP, I'm thinking they appear to be a worthwhile upgrade for the dollar, but I don't know what performance at this level actually sounds and feels like. Would this upgrade be worth the $280 it would cost me for the two Dayton subs versus the two Phoenixs?
There would be a noticeable difference with the Daytons, however, try the Phoenix subs first. If they provide all you need then great, if not, then upgrade.
The Dayton Audio DVC 385-88's are on sale. $119, down from $139. Must..control..self..must..control..self...:sweat:
Another lil update. The second Bash 300S came in from ebay, as did the terminals from partsexpress. I'm running out of excuses to get this started.....except football season. A little nervous, don't want to mess this up. First build jitters? Is that a legit condition?
Oh by the way, I know what chuffing sounds like now. That Polk Audio PSW10 chuffs like crazy during movies and the tv series "Once Upon a Time". Read a ton of reviews, pulled the grille and hardly any better. Gain only set to 60%. Can I use this sub as a mid-bass when the 15's are done? Say crossed over at like 60hz? See, I have this old, but never installed Kenwood KEC202 car crossover.....:laugh: Seriously..MikeP, thoughts? With a 12v power supply, could this work?

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I bet I'm totally missing something, but it would seem that using the primary Yamaha receiver low pass 120hz output I could feed it to the crossover inputs with a y adapter. Send high pass side to the Polk, and low pass to the Bash driven 15's.
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The LFE from the reciever should feed the Bash amps. Use a Y adaptor from the LFE to the KEC202 and Polk if you want more mid bass.
Coach Mike, you suggest bypassing the KEC202 for the Bash driven 15s. That means using the Bash low pass crossover, and matching it to the high pass from the 202 crossover for the psw10. I'm cool with this, but wonder why. Is the 12db low pass in the Bash better than the 18db in the 202? My second question is regarding the signal from the Yamahas sub out. Does splitting twice it degrade the signal strength enough that the auto on/off in the amps will have trouble working? Does an active crossover boost that output current like a preamp?
Coach MikeP, a couple more questions. As far as box dampening goes, it seemes most folks like an egg crate style lining in ported boxes, and stuffing in sealed. And nothing through the length of the port slot itself. Your experience says what? I see that egg crate stuff seems to be made of two different materials, one yellowish, and one black. Is one better than the other? And if it makes no difference, I'm almost sure I recently read you mention a really cheap walmart pillow to somebody. What is this pillow made of? Next topic...box feet and elevation from floor. I have wood laminate flooring over concrete slab. I already picked up a couple sets of those partsexpress solid rubber feet, but I like the idea of those little caster wheels, is there a problem with those? I really dont see many folks using them in their builds..
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