Help me make a decision on a DIY sub.... - AVS Forum
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post #1 of 13 Old 02-19-2013, 08:47 AM - Thread Starter
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I have gone through a number of subwoofers that left me wanting in my home theater... I had a couple of Polk PSW650s which provided some tight bass but it was lacking any signal below 35-40Hz. I also had a Sunfire True Subwoofer Mark II (of course, the amp died). While it provided the low end extension I wanted, the bass was bloated and tubby sounding and was missing the mid-bass. I currently have a Definitive Technology SuperCube 6000. To be frank, it is mediocre, three 9" drivers (two passive) was just not cutting it. I also had a Parts Express Titanic MK III 15" subwoofer. While it actually provided the bass extension I was looking for, the box was way too huge, being a 21" cube. What I am looking for is tight bass (making a sealed cabinet a requirement) with a decent extension. I am not into LOUD, I just want accurate bass there when it is called for.

I am currently considering a dual JL Audio box with a pair of 12W3v3 2-ohms drivers in a series config (they weigh about 15 lbs each) with a 500-watt sub amp. According to the TS parameters, the box should be 18" x 19" x 20". It was also recommended that the plate amp be in a separate chamber from the sub as the pressure in a sealed system can wreck havoc on the electronics, so I do have to adjust the cabinet volume accordingly.

My other option is a single Dayton Audio 12" HF driver (this weighs 25 lbs) in a sealed box with the same amp roughly about 16" cubed.

Both designs will have a -3dB point of about 50Hz and will be -6dB at 35Hz. I am going to build it with 1-inch MDF on all sides. What do you guys think of the options and what would be the pros/cons of each design?

Is there an advantage going with dual drivers over a single?

If going with a dual driver with a 500-watt amp, do you calculate the system parameters with 500-watts total or 250-watts (per driver).

Is it better to go with two 8-ohms drivers hooked up in parallel or dual 2-ohms drivers in series to get to 4-ohms overall?

Thanks in advance...

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post #2 of 13 Old 02-19-2013, 12:55 PM
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Sound like you are setting yourself up for disappointment again.
How big is your room? Treated?

I'd recommend one Dayton PA-18 and one Dayton HO-18 in a box size you can live with,
hooked up to a nu3000DSP.

Here is what my PA-18 and SDX-15 sounds like in 3200cu-ft with minimal treatments, with only two EQ filters applied by ear:

I'm using a bit more power than a nu3k here, but it would STILL be more SPL than most people are willing to tolerate;
Especially wives in dwelling residences; rather than my dedicated/detached soundproofed bunker biggrin.gif
and it's as clean sounding as my LMS Ultra... well almost biggrin.gif

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post #3 of 13 Old 02-19-2013, 01:22 PM
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Based on everything you've said, I recommend a Dayton RSS390HO in a box as small 1.5ft3 with the Yung sd500-6 amp.

This will get you a compact, extremely clean sounding sub thats only real limit is low end max output.
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post #4 of 13 Old 02-19-2013, 01:25 PM
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Tough to fulfill all your requirements. It needs to be sealed, play deep, and be in a relatively small box.

Sounds like the Titanic is as close to perfect as you are going to get. 21" cube isn't that big, is it?

You could do dual-opposed TC Sounds Epic 12" DVC subs, that wouldn't be a much smaller box.

Is cost also an issue? You could look at doing a TC sounds 12" Sub with 2 12" passive radiators,
or a Dayton RSS315HF-4 with an AE 15" passive radiator...
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post #5 of 13 Old 02-19-2013, 03:27 PM - Thread Starter
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I had a Titanic 15" in a 21" cube box with a 1000-watt amp... It was way too big for the room... Either way, a 12" Titanic MK III is out of the question... Parts Express is currently out with an expected available date of June 2013. I understand that the 12" Dayton Audio Reference HF sub is supposed to be tighter and more accurate than the HO or the Ultimax which are designed more for bass output than accuracy.

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post #6 of 13 Old 02-19-2013, 04:02 PM
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Quote:
Originally Posted by Jon S View Post

I had a Titanic 15" in a 21" cube box with a 1000-watt amp... It was way too big for the room... Either way, a 12" Titanic MK III is out of the question... Parts Express is currently out with an expected available date of June 2013. I understand that the 12" Dayton Audio Reference HF sub is supposed to be tighter and more accurate than the HO or the Ultimax which are designed more for bass output than accuracy.

High excursion subwoofers are more effective for low frequencies (such as, below 40hz).
High efficiency subwoofers are more effective for frequencies above that.
So you kind of need both to do it properly.

A HF-12 is a middle-of-the-road solution, the PA-18 is more efficient than it and the HO plays deeper than it; the combination of the two is of course better; hence my recommendation. The HF-12 doesn't do either as well, it's sort-of in the middle. (In this case, you get what you pay for.)

However given your size restrictions you could just select the smaller cone equivalents of the PA/HO (I believe them make them both in 12's).
You'll lose SPL and dynamic range, but you'll save money and space.
You could even downgrade to a nu1000dsp, even less dynamic range and SPL, but saving money.

You will still need some sort of DSP/XO/EQ to make it all work well. Room treatments and correct subwoofer placement helps as well.
Otherwise sound quality will suffer.
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post #7 of 13 Old 02-19-2013, 05:27 PM
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Quote:
Originally Posted by Jon S View Post

I had a Titanic 15" in a 21" cube box with a 1000-watt amp... It was way too big for the room... Either way, a 12" Titanic MK III is out of the question... Parts Express is currently out with an expected available date of June 2013. I understand that the 12" Dayton Audio Reference HF sub is supposed to be tighter and more accurate than the HO or the Ultimax which are designed more for bass output than accuracy.

This notion about the HF vs HO doesnt really have much credibility. One series is designed for use in a large sealed box (HF) and the other for a small box (HO) ported or sealed. Take a box that's 16 x 16 x 17 and place the 15" HO in it with the boosted 500 watt Yung amp, and this is what you're looking at



Nothing bad about that for such a small sub, and distortion will be lower then a 12" driver. Like I said before, all you're limited by is maximum output at the low end, which is related to the boost.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-469

http://www.parts-express.com/pe/showdetl.cfm?partnumber=301-514
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post #8 of 13 Old 02-22-2013, 03:20 PM - Thread Starter
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Thanks Jay1.. I am now looking at this configuration... Do you think it will work?

Box will be a 18.5" cube.... walls are all 1" MDF. Driver will be the RSS390HO-4 15" subwoofer

The box will be divided into two separate sections. The sub will be in the front (16.5x16.5x10.25" or about 2790 cu in or 1.6 cu ft internal volume).

The amplifier (Dayton SPA-500) will be in the rear section (16.5x16.5x5.5") sealed from the front to prevent any air leaking and any compression issues from the driver.

My question is if it is necessary to put the amp in a separate section from the speaker... i have seen plenty of subs with the amp in the same enclosure as the driver. I really want to make the cabinet as small as possible. I talked to Parts Express and they recommended using the 18.5" cube without the double enclosure for better sound. They said that the Q of .707 is not ideal for room environments and that the enclosure should be bigger than what is recommended. What do you think?

Thanks in advance...

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post #9 of 13 Old 02-22-2013, 03:59 PM
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That's way to small of a box for the HF. You dont need a separate enclosure for the amp.

The setup I recommended was for the HO, and included an amp with boost.
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post #10 of 13 Old 02-22-2013, 06:57 PM - Thread Starter
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I'm sorry, I meant the HO driver for the specs, not the HF... So it should work? I just did the same config with Bass Box Pro and it was giving me a QTc of 0.593. Is that too low? What would be sound affect with that low a QTc?

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post #11 of 13 Old 02-22-2013, 07:51 PM
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Quote:
Originally Posted by Jon S View Post

I'm sorry, I meant the HO driver for the specs, not the HF... So it should work? I just did the same config with Bass Box Pro and it was giving me a QTc of 0.593. Is that too low? What would be sound affect with that low a QTc?

Qtc is only really to low if you have more power then the driver can handle. I'm not sure how you're getting .59, should be closer to .65.

The HO wont get very deep in a sealed box, unless it has boost applied, which is why I recommended an amp with 6 db boost at 25hz. Your proposed setup will have a -3db point of about 46hz, using the Yung SD500-6, the -3db point will be about 28hz.
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post #12 of 13 Old 02-22-2013, 09:59 PM
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yeah, be careful there as most plate amps have a 2nd order high pass filter around 20hz or so. this causes them to rolloff earlier than most folks would like. although depending on how you intend to use the sub, you may be able to cheat the frequency response with the variable low pass filter.

Listen. It's All Good.
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post #13 of 13 Old 02-23-2013, 04:54 PM - Thread Starter
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How is this then? 16" cube. 1" walls with the 15" HO driver. The amp will take up 14x14x5" or 980 cu in. The driver takes up 405 cu in volume as well. The speaker enclosure will be 14x14x9" or 1764 cu inches. i think that comes to a QT of about .7... The F3 ends up at 55Hz though. If i boost the EQ to +6dB at 35Hz, the -3dB is at 47Hz and -6db is at 30Hz. according to Bass Box Pro...

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