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Discussion Starter #1
There are a few experts on this board and for some reason, there are no sticky threads to use as a reference.


I want to build a DIY subwoofer and would love to get suggestions. No one responded to my previous thread so I thought I would try a different approach....


I want to build a sealed DIY subwoofer that will equal two JL Audio Fathoms and absolutely crush my current M&K MX5000THXs.


Please use your expertise to tell me the top 5 15" drivers for a sealed application and tell me your top 5 pro amps with a street price of under $1200 (these can be used on ebay or refurbs) that can properly power the 15" drivers for output and SQ.


I realize this is vague, but I hope it gets a response.


Thanks
 

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I think if you want to equal a pair of fathoms, you might need an infinite baffle. For sealed, it will be very difficult to equal a pair of fathoms with a single driver. I'd be looking at a pair of 15" TC 3000's in separate enclosures, or even two enclosures, each with a pair of 15" TC 3000's. That would probably equal or better the perf of a pair of fathoms. Others will have to comment on amp choice, but you'd probably want 1500-2000 watts per driver.
 

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Discussion Starter #3
Thanks for getting this started. I cannot do IB. But I can and will do any of the following:

15" Single driver sealed

2 15" drivers - 2 sealed boxes

Dual 15" driver sealed - one box - (if viable - a push-pull design like my M&K)

Single 15" driver - single 15" PR - one box

Single 15" driver - dual 15" PR - one box


Overall budget should be in the $1500 - $1750 range.


Looks don't matter, but size does. Unfortunately, depth can only be 16.5" (it is the depth behind my projection screen). The box or stacked boxes can be up to 4 feet wide and 5 feet tall.


Thanks

Matt
 

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Hmmm....with that budget, it will be even tougher to meet or beat the perf of a pair of Fathoms in a sealed configuration. With the dimensions you specify, you have roughly 22 cu ft. to work with. That's probably way off, I just multiplied 4 time 5 with a couple extra cu ft. thrown in since your depth is 16.5". Also, you'll want to subract 20% for driver and bracing volume. At that budget, I'd probably go with a pair of 15" TC2K's at $550 for the pair, a pair of Crown XTi 1000's which when bridged will give you 1400 watts per driver: http://www.musiciansfriend.com/produ...ier?sku=481588 . That puts you right at 1500, so there's 250 or so left for the enclosure. I don't know how close to dual Fathom perf that setup would get you, but I'll bet pretty close. You'll also need a few hundred for EQ, and bass traps would be a good idea as well. In fact, if I had a choice between EQ and bass traps, I'd go with the bass traps. Here's another approach: A single 15" TC 3000 in a ported enclosure with the aforementioned Crown amp which puts you right at $900, say another $200 for a BFD (Behringer Feedback Destroyer) for EQ, 200 for the enclosure (assuming you build it yourself), and you have 450 left over for bass traps. That setup would probably go as low or lower than a pair of Fathoms and the sound quality would be pretty close as well, esp with the bass traps. Correcting room issues goes a VERY long way towards providing deep, clean bass.


Others can probably chime in as well, there are a few different solutions here.
 

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Discussion Starter #5
Just a little more info.


This is going into a theater room that was designed for bass (and overall sound) performance. ie: there are bass traps in the front two corners and the back wall, all four walls and the ceiling are treated and the riser is also designed as a bass trap.


The stage that the sub will sit on is double MDF floor and is filled with sand so the room needs no further consideration.


I do have an EQ - it is a Velodyne SMS-1.


I am not counting the cost for the box in my overall budget because I have a very large credit at Home Depot from returns I did after the HT build.


Thanks
 

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Wow, that's quite a room you have! I also have an SMS-1 which I really like, it's nice to see the effects of adjusting EQ in real time right on the TV screen. Since the room is good to go, and the enclosure is essentially 'free', I guess there's no $ needed for anything other than drivers and amps. Since you have a fair amount of space to work with, let's say 22 cu ft which will give some clearance between screen and the front of the enclosure, you could do 4 15" TC 1000 dual voice coils, wire the two 4 ohm voils coils in series for an 8 ohm load per driver, then wire a pair of drivers in parallel for a net load of 4 ohms and have one Crown XTi 1000 drive two woofers each. So, you'd have 1400 watts bridged per amp driving a pair of TC 1000's into a 4 ohm load. That would put you at $1800. Or, you could do a pair of the higher quality TC sounds drivers.

www.tcsounds.com
 

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Discussion Starter #7
Thanks, now we're getting somewhere. 4 drivers seems pretty impressive and I would have plenty of room. Would I get good sound quality from the TC1000 drivers?


I am wondering if my best bet for drivers would be one of the TC LMS 5400 1" with two passive radiators. Because of the clearance, the woofer would have to fire sideways, just as my MX-5000 does today. I would have to build my box pretty narrow and the edge of the speaker would almost reach the edges, but I think it could be done. The two PR would be opposite of the LMS 5400 driver. They are not it stock, but I am not in a huge hurry. What does anyone think??
 

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The passive radiator idea would probably work well also. I don't know how a LMS driver with a pair of radiators would compare in sound quality and excursion to 4 15" TC 1000's sealed though. The LMS with passives might dig a little deeper.
 

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Quote:
Originally Posted by Video /forum/post/0


Thanks, now we're getting somewhere. 4 drivers seems pretty impressive and I would have plenty of room. Would I get good sound quality from the TC1000 drivers?


I am wondering if my best bet for drivers would be one of the TC LMS 5400 1" with two passive radiators. Because of the clearance, the woofer would have to fire sideways, just as my MX-5000 does today. I would have to build my box pretty narrow and the edge of the speaker would almost reach the edges, but I think it could be done. The two PR would be opposite of the LMS 5400 driver. They are not it stock, but I am not in a huge hurry. What does anyone think??

1 LMS 5400 with 2 PRs is what I chose. I am building duals. I had a pair of fathoms. There is a long thread here if you are interested, check it out.

Good luck,

-Jai
 

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Discussion Starter #11
Thanks Jai. Are they done yet? How long is the wait for drivers? I can only use the 15" because of box size limitations. Will you have the woofer on one side and the PRs opposite?


Thanks for the response
 

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Why couldn't you use 18's and front fire them? That would allow roughly 15" for speaker depth. Plenty if you ask me.
 

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Discussion Starter #13
So no problem with making the box wide and shallow? On my calculations with a box that shallow, the back of the driver could be as close as 1/4" - is that too close to the back of the box? Also, will this move so much air that the cloth under the screen will ripple during huge bass scenes? The cloth around the screen is black GOM 703 so it is acoustically transparent, but I can imagine that an 18" could still move the cloth under the screen. The GOM cloth would end up being about 3 1/2" from the front of the sub. Any thoughts??
 

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You could have the subs fire into the rear wall, but have the enclosure an inch or less from the screen to give more room for the sound to radiate out. Or you could still mount the subwoofers on the sides of the enclosure, but cut the sides at a 45º angle instead of a 90º angle. That would then change the mounting surface from 15" to 21".
 

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Discussion Starter #15
Back wall is covered with 4" of cotton batting so I think it would absorb a lot of the bass. I think they need to fire out in some way. I like the 45 degree idea. Hopefully, there would be enough depth if they were set at an angle.
 

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Quote:
Originally Posted by Video /forum/post/0


Thanks Jai. Are they done yet? How long is the wait for drivers? I can only use the 15" because of box size limitations. Will you have the woofer on one side and the PRs opposite?


Thanks for the response

They are in stock. Go grab them while you can. Woofer is front firing and PRs are both side firing. Please look back a few pages in my thread to see what the final design looks like. I have a google sketch that shows some good details.

Hope this helps,

-Jai
 

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Quote:
Originally Posted by deneb /forum/post/0


I'd be looking at a pair of 15" TC 3000's in separate enclosures, or even two enclosures, each with a pair of 15" TC 3000's.

The problem with the TC3k is that it's a very high inductance driver. Now that the TC1k's are back in stock, that's a very solid way to go if cabinet volume is not an issue


The five best 15's I've personally played with are the following:


1) JBL W15GTi. Extremely low inductance, clean motor, low distortion, cool dual gap/dual coil motor design, enough heatsinking to make power compression basically a non-issue, works well in a 4 cubic foot sealed box. Only negatives are the depth and the chromed plastic dustcap. My new reference.


2) Aura NS15. Underhung motor, light weight, probably the overall most sophisticated design out there right now. Bloody expensive, though.


3) JBL 2235H. True, not capable of nearly as much output as anything else on the list. It only has about 8mm of xmax, and that's a hard limit due to the fact that the mass ring at the base of the cone will get jammed at excessive excursions. But within its limits, utterly exceptional sonic performance. No longer made, but reasonably widely available.


4) TC Sounds TC1000*. Lowest inductance per ohm of TC's lines, and excellent measured distortion performance of the TC2+ motor. (*I've not actually used the TC1k. My experience is with the TC2+ variant that Oaudio commissioned. It is designed for lower efficiency and lower Qtc in a given box size.)


5) Dayton Titanic Mk. III. Often overlooked because it's been out for a while, it's very similar to Nick McKinney's old Lambda Acoustics LE-series.



I've not played with other possibly worthy drivers, such as the Dayton Reference 15, and obviously none of the ones in the works.


As for amps, I think the Crown XTi series defines the current sweet spot, because they have sophisticated processing onboard, heaping loads of power, and fair pricing.
 

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Quote:
I did the break down for our drivers...I used Ls, not Le. Le is the inductance measured at 1000Hz, its a very old method that is not accurate for the entire spectrum. Ls/Lp + Rp is a circuit that models the inductance over the frequency much more accurately. (I'll look for a good picture of this later)


TC-3000 1.9 mH/Ohm, BL^2/Re = 410

TC-5200 1.45 mH/Ohm, BL^2/Re = 160

TC-7 0.796 mH/Ohm, BL^2/Re = 60

LMS-5400 0.775 mH/Ohm, BL^2/Re = 45

TC-2000 0.774 mH/Ohm, BL^2/Re = 100

TC-9 0.73 mH/Ohm, BL^2/Re = 140

dB-500 0.73 mH/Ohm, BL^2/Re = 50

TC-1000 0.67 mH/Ohm, BL^2/Re = 65
Quote:
Now that the TC1k's are back in stock, that's a very solid way to go if cabinet volume is not an issue.

I think the TC-2000 deserves a look as well. You always talk about the 1000, but its not as if the 2000 has significantly higher inductance. However it does have higher power handling, larger VC, and more excursion.
 

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Thanks for posting Kyle's chart, Will. I'm going to copy it, with the five woofers I listed bolded and when applicable added. (I left out Re/BL^2 on the woofers I added because I don't think it tells us anything that Qes doesn't.)


TC-3000 1.9 mH/Ohm, BL^2/Re = 410

TC-5200 1.45 mH/Ohm, BL^2/Re = 160
Dayton Titanic 15 1.04 mH/Ohm

TC-7 0.796 mH/Ohm, BL^2/Re = 60

LMS-5400 0.775 mH/Ohm, BL^2/Re = 45

TC-2000 0.774 mH/Ohm, BL^2/Re = 100

TC-9 0.73 mH/Ohm, BL^2/Re = 140

dB-500 0.73 mH/Ohm, BL^2/Re = 50
TC-1000 0.67 mH/Ohm, BL^2/Re = 65
JBL W15GTi 0.34 mH/Ohm
JBL 2235H 0.2 mH/Ohm
Aura NS15 0.10 mH/Ohm


See a pattern?



(FWIW, I ranked the W15GTi over the Aura mostly because of the signficant street price difference between them. Also, I've never heard them in the same room. Had I heard the NS15 more recently, that might have been my top pick.)

Quote:
Originally Posted by Willd /forum/post/0


I think the TC-2000 deserves a look as well. You always talk about the 1000, but its not as if the 2000 has significantly higher inductance. However it does have higher power handling, larger VC, and more excursion.

Fair point there, though I wouldn't consider ~15% higher normalized Le to be insignificant. The main reason I don't mention it is simply because I've never played with it myself, nor seen third-party measurements of the raw driver. It would be irresponsible for me to suggest something I've not personally tried.


That said, on paper the TC2000 looks impressive, and certainly Illka's measurements bear that out. Though the inductance is higher than that of sub drivers I tend to like, unlike the TC3k it's not so much so as to make it beyond consideration should the need for a new driver arise.
 
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