4 mobile subwoofers in my HT

Chongdigga

Chongdigga

Audioholic Intern
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IMG_0102_zpsgkgdsk5u.jpg

CV LW10 Powered 10" subwoofer (Now a CV HED mobile 10")

Crunch 5050.5 1000w mobile audio amp
14v regulated power supply
3 farad capacitor

CV H4124D 12" HED Mobile subwoofer in a vented box tuned to 33hz

2 CV H4104D 10" HED Mobile subwoofers in Labyrinth vented boxes tuned to 44hz
IMG_0116_zpsnrrh0hhy.jpg

Replaced the lw10 with another CV HED 10" (not in 1st pic)

About to get another 12" and a Crown xls1000 amp to power both 12"s and put the mobile amp and the 2 10"s in my SUV
 
rojo

rojo

Audioholic Samurai
Mr. Digga, your presentation is impressive. I can tell you're extremely proud of your gear. I must say, though, that automotive subwoofers rarely perform well in a home theater setting. The high Fs and ~40Hz vent tuning is intended to take advantage of an automobile's cabin gain.

Boundary gain / corner loading notwithstanding, that gain will not be as profound in a home theater setting. The 12" HED, properly tuned to 27.7Hz in a 3 - 5ft³ box hits 20Hz at around -10dB. Those don't look anything like 3 to 5 cubic foot boxes, though -- more like 1.5? In a 1.5ft³ box tuned to 33Hz, you're -3dB at 34Hz, -10dB at 24.5Hz, and at 20Hz you're down 15dB. And that's the best of your subs! I'm not even going to bother modeling your 10's. I daresay your system is loud and has obscene thump (with that one sub hitting 118dB around 58Hz with 600W of power), but has no rumble. I'm sure it's a sound worthy of the silkiest, most magnificent mullet when rocking out, but you're missing so much of the LFE channel with movies.

I suggest that if you sold all your CV subs and enclosures, Crunch amp, and 3 farad cap, then put the money toward a single Reaction Audio Echo 15, you would get a much more satisfying movie experience. Maybe you could still put a vinyl CV logo on its dust cap, though.

I sincerely apologize if I have urinated in your Corn Flakes. It's not my intention to ruin your day. I can tell you have put a lot of time and effort into your setup, and you have constructed quite a fortress there. I can't help but marvel at it.
 
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Chongdigga

Chongdigga

Audioholic Intern
It started as an "I'm very bored experiment" and I kinda got carried away.

I like constructive critasism and yours was very polite. I've been told similar things in other forums but not as nicely.

I admit the two 10s in the labyrinth boxes are a big time miss match and aren't really doing much. They are going into my car soon in different boxes along with the amp.

Just to clarify... The 12" sub has the potential to sound better if it was in the right enclosure?? The manual for it said a 1.5 cu ft vented box but that's for the mobile world right? Say if I built a box to HT specs could that mobile sub sound better?

I played a Hz test thru my surround and the 12" and the 10" (in the HT powered box) sounded great imo and hit all the way down to 22hz or so and only really noticed a peak in the 12" around 33hz.

I really like how the 12" plays movies. I have 2 kids so I don't blast it very often but can make blue's (Rio) wings flapping pull at ur chest if I turn it up. Frozen will rattle the windows LOL. I've never heard a pro surround setup b4 tho so I don't have anything to compare it to. Everyone that hears it says its like being in a movie theater.

I'm still a major noob. Didn't even know about ohm matching or anything about frequencies 6 months ago. I'm in it too deep to stop now so I'm committed to get it to sound as good as it can. Like I said the 2 10" and mobile amp r going into the car and I want to get another HED 12" and a crown xls1000 amp at an 8ohm load for the HT. I would be willing to build some huge tower boxes If that's what it takes.
 
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WaynePflughaupt

WaynePflughaupt

Audioholic Samurai

To a certain point, yes. However, if you get the box too big the drivers will more easily bottom out.

Regards,
Wayne A. Pflughaupt
 
fuzz092888

fuzz092888

Audioholic Warlord
If nothing else, looks cool :D

PS those height speakers need to be angled down in a bad way. Otherwise you're wayyyy off axis vertically, which I can't imagine is a good thing.
 
Chongdigga

Chongdigga

Audioholic Intern
If nothing else, looks cool :D

PS those height speakers need to be angled down in a bad way. Otherwise you're wayyyy off axis vertically, which I can't imagine is a good thing.
I read that but don't know a way to tilt those monsters without one falling and taking out one of my kids. Ive had to make some sacrifices because of the kids. I would like a sub in each corner but nope. My grills never come off the surrounds either. Only a matter of time till there is a crayon or something jammed thru it and my woofer :( I'd flush em but there heads are too big ;)
 
Chongdigga

Chongdigga

Audioholic Intern
Mr. Digga, your presentation is impressive. I can tell you're extremely proud of your gear. I must say, though, that automotive subwoofers rarely perform well in a home theater setting. The high Fs and ~40Hz vent tuning is intended to take advantage of an automobile's cabin gain.

Boundary gain / corner loading notwithstanding, that gain will not be as profound in a home theater setting. The 12" HED, properly tuned to 27.7Hz in a 3 - 5ft³ box hits 20Hz at around -10dB. Those don't look anything like 3 to 5 cubic foot boxes, though -- more like 1.5? In a 1.5ft³ box tuned to 33Hz, you're -3dB at 34Hz, -10dB at 24.5Hz, and at 20Hz you're down 15dB. And that's the best of your subs! I'm not even going to bother modeling your 10's. I daresay your system is loud and has obscene thump (with that one sub hitting 118dB around 58Hz with 600W of power), but has no rumble. I'm sure it's a sound worthy of the silkiest, most magnificent mullet when rocking out, but you're missing so much of the LFE channel with movies.

I suggest that if you sold all your CV subs and enclosures, Crunch amp, and 3 farad cap, then put the money toward a single Reaction Audio Echo 15, you would get a much more satisfying movie experience. Maybe you could still put a vinyl CV logo on its dust cap, though.

I sincerely apologize if I have urinated in your Corn Flakes. It's not my intention to ruin your day. I can tell you have put a lot of time and effort into your setup, and you have constructed quite a fortress there. I can't help but marvel at it.
OK so I ran my 12" sub's specs thru a HT enclosure calculator and it needs (as you stated) a 5.68 cu ft box with a 4" diameter 8.64" length port to have a flat response. I'm going to try to get up to my buddies this weekend and build a 40"H x 15"W x 19"D box and see what happens.
 
rojo

rojo

Audioholic Samurai
OK so I ran my 12" sub's specs thru a HT enclosure calculator and it needs (as you stated) a 5.68 cu ft box with a 4" diameter 8.64" length port to have a flat response. I'm going to try to get up to my buddies this weekend and build a 40"H x 15"W x 19"D box and see what happens.
That's tuned below the Fs of the driver. You'll get more low-end extension, but you'll also get a muddier sound with a splayed impulse response from that configuration I think. Also, pay attention to the port velocity, and aim for < 20m/s @ 125W to avoid chuffing. Better to do a 5ft³ box with three 3" x 12 5/8" length ports, or two 4" x 14 5/8" ports, whichever you prefer. In a 5ft³ box, you could also do a slot vent 2" high, 12" wide, and 12 3/4" long.
 
Chongdigga

Chongdigga

Audioholic Intern
That's tuned below the Fs of the driver. You'll get more low-end extension, but you'll also get a muddier sound with a splayed impulse response from that configuration I think. Also, pay attention to the port velocity, and aim for < 20m/s @ 125W to avoid chuffing. Better to do a 5ft³ box with three 3" x 12 5/8" length ports, or two 4" x 14 5/8" ports, whichever you prefer. In a 5ft³ box, you could also do a slot vent 2" high, 12" wide, and 12 3/4" long.
Sounds like a plan. Prob go with the 3 ports and position them in a cool way. Does port position or distance apart from each other matter?

I greatly appreciate the advice. Keep it coming :)
 
rojo

rojo

Audioholic Samurai
To my knowledge, vent placement isn't crucial. Don't forget to add the displacement of the driver (probably 0.07ft³) + the displacement of the ports and bracing to find the gross internal volume needed to net 5.0 cubic feet.

You could also look for some sort of 3" plugs and play with variable tuning, Hsu VTF style. :)

Sent from my LG-VS980 using Forum Fiend v1.3.1.
 
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Chongdigga

Chongdigga

Audioholic Intern
To my knowledge, vent placement isn't crucial. Don't forget to add the displacement of the driver (probably 0.07ft³) + the displacement of the ports and bracing to find the gross internal volume needed to net 5.0 cubic feet.

You could also look for some sort of 3" plugs and play with variable tuning, Hsu VTF style. :)

Sent from my LG-VS980 using Forum Fiend v1.3.1.
Got most of the materials today. Going to try to get them built this weekend. Try to sand and paint next weekend.

I calculated the total displacement of ports, bracing, sub and got .300 so I'm going to build two 17"Wx40"Hx17"D 5.28 cu ft (rounded a little to get easy measurements) boxes with three 3"x 12 5/8" ports on the front sub side in an upside down pyramid above the sub.

Using 3/4" MDF (Lowes)

Any final tips hints or corrections of my lack of mathematic skills let me know OK :)

Polyfil Y/N?
 
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rojo

rojo

Audioholic Samurai
That looks right to me. You calculated 5.28 cubic feet gross, ~5ft³ net, right? Anyway, I'm struggling to verify the port lengths. For a tuned frequency of 27.7Hz:
I think 13" is probably correct, or close enough for government work anyway (assuming you aren't using flared ports). Are you using flared ports, or just generic plumbing PVC pipe?

Polyfil shouldn't be needed, but you can certainly experiment and salt to taste with it if you have some (or an old throw pillow you were planning to throw away).
 
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Chongdigga

Chongdigga

Audioholic Intern
That looks right to me. You calculated 5.28 cubic feet gross, ~5ft³ net, right? Anyway, I'm struggling to verify the port lengths. For a tuned frequency of 27.7Hz:
I need to verify the length before you commit with glue and a saw I think. Are you using flared ports, or just straight plumbing PVC pipe with an elbow or two?

Polyfil shouldn't be needed, but you can certainly experiment and salt to taste with it if you have some (or an old throw pillow you were planning to throw away).
Just added the total displacement to the cu ft of the box right?

Planned on straight PVC attached inside the box and route/flare the front 3/4" MDF. Will a flare affect length?

Thanks again for all the research and tips.

Might possibly start the build 2night if my buddy is up for it. I will wait for your final port decision b4 I go too far tho. Shouldn't affect the port placement that I have planned if the length changes either. Box is 17" D so I have some room to play with.

Actually if the port length changes so will the displacement and box size so I will wait till I hear from you.
 
Chongdigga

Chongdigga

Audioholic Intern
I hear winISD is basically the "go to" calculator. 12" and 21" is a pretty big difference tho eh?
 
rojo

rojo

Audioholic Samurai
Yeah, but I just started using Torres yesterday. I don't have much confidence in its tuning calculations anyway, although it does seem to be useful for calculating the displacement of drivers, vents, and bracing.

Flaring one end makes the ajdesigner web-based calculator agree with WinISD on 12 5/8".

I must say, you're committing a lot of effort and expense in materials to a project that will still yield mediocre results. Don't get me wrong. It'll be an improvement. I predict you'll gain about 8dB at 30Hz with this mod. But it still won't quite reach subsonics with authority. A driver with a lower resonant frequency (an Infinity 1260w, for example, or a Dayton Titanic 15" if it's in your budget) would be better suited for a home theater build.
 
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Chongdigga

Chongdigga

Audioholic Intern
Yeah, but I just started using Torres yesterday. I don't have much confidence in its tuning calculations anyway, although it does seem to be useful for calculating the displacement of drivers, vents, and bracing.

Flaring one end makes the ajdesigner web-based calculator agree with WinISD on 12 5/8".

I must say, you're committing a lot of effort and expense in materials to a project that will still yield mediocre results. Don't get me wrong. It'll be an improvement. I predict you'll gain about 8dB at 30Hz with this mod. But it still won't quite reach subsonics with authority. A driver with a lower resonant frequency (an Infinity 1260w, for example, or a Dayton Titanic 15" if it's in your budget) would be better suited for a home theater build.
I only have $50 invested (not counting subs)but if I build the boxes as planned and wanted to change the sub to a lower Fs someday then the only changes to the enclosure would be the port length right?

That infinity is the same price I paid for my CV too.
 
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rojo

rojo

Audioholic Samurai
Tuning lower than the driver's resonant frequency will splay the impulse response and make your sub sound muddy. Some more dubious subwoofer manufacturers do this to be able to publish more impressive frequency response numbers, but their subs don't sound very tight.

Here, I graphed some stuff:
  • Red: estimated current response curve of your CV H4124, 300W@1m
  • Orange: predicted result of building a 5ft³ box tuned to 27.7Hz, 300W@1m
  • Green: Infinity driver, 3ft³ box tuned to 23.83Hz, 300W@1m
  • Cyan: Titanic 15", 5.8ft³ box tuned to 16.8Hz, 600w@1m

They're all Xmax limited to show what the excursion limits will allow. Notice that even the improved box will be 7dB quieter than the Infinity at 20Hz. The Titanic would pretty much handle just about anything you could throw at it, short of an iceberg.

Edit: Well, actually, at a more typical power level of 100 watts, the Infinity is only 2dB higher than the CV at 20Hz. It's probably not worth $70 for that inconsequential of an improvement, now that I ponder the matter. I'm starting to see the value in your project now.
 
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Chongdigga

Chongdigga

Audioholic Intern
Got to get a little done today. Cut all the panels to size and fit the ports to the inner brace :)
Still a ways to go.

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My buddy who has all the tools and did most of the work
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I wonder what one of these monsters would sound like in my SUV ;)
 
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Chongdigga

Chongdigga

Audioholic Intern
So my buddy is golfing today and tomorrow so won't be able to work on them till Wednesday.

Hey rojo
I know I getting ahead of my self but if these boxes are successful then I'm thinking down the road I would like to build two big down firing boxes (so my kids can't get to them) for two 15" subs and use them as surround stands for my CV vs100s up against the wall on both sides of the couch. Put something like this http://www.parts-express.com/dayton-audio-dcs385-4-15-classic-subwoofer-4-ohm--295-206 in them. What do u think?
 
rojo

rojo

Audioholic Samurai
Hmm. Not bad. In a 5ft³ box, same as you're buiding now but tuned to 17.5Hz, it'll handle about 150W before reaching Xmax. At that power, it'll play down to 15Hz @ 99dB, 20Hz @ 104dB, have an F3 of 24Hz, and average ~110dB from 34Hz+. It'll be a couple dB shy of your Cerwin Vega at higher frequencies, but it will more authoritatively pressurize the room into subsonics I think. A single flared 4" dia x 19" vent ought to be fine, although there could be some chuffing below 16Hz. Since the sub will be Xmax limited below 14.2Hz anyway, I doubt it'll matter.

If you could budget an extra $25 per driver, this Dayton 12" DVC in a net 3.7 cubic foot box tuned to 19.5Hz would outperform the 15" Classic from 16 - 33Hz (4dB louder at 20Hz at 300W). It'd need two 3" by 24 3/4" flared vents.
 
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