Planning Another twin floor standing Subwoofer build - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 25 Old 08-20-16, 11:29 AM Thread Starter
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Planning Another twin floor standing Subwoofer build

Okay so after much hopefully useful cerebral activity, I have decided am going to do another pair of floor standing subs almost identical to the ones I did and posted on this thread in another forum. http://forums.audioholics.com/forums...r-build.97538/. My goals are moderate sub20hz extension at a moderate spl in a moderately small enclosure. My subs are same as I used in the previous build (and still have are a pair of)12 inch Epik sentinel drivers. Typically they achieve good sub20hz extension in small enclosures. I have attached the driver data and WinISD Sim files. Essentially this is a 3(net)cuft ported enclosure tuned to 18hz. Previously I used twin flared round ports and tuned to 19hz but I plan to get a longer, wider port by doing a slot port and this will increase the enclosure depth, hence the difference from the Previn ious twins. It will be 39.5 inches tall(minus feet), 14.5"W and 17"D. The slot will be bottom of baffle beneath the driver, and 13"W, 1.75"H and 51.625" deep, folding off of the bottom, up to the upper end of the back. It will have top, bottom and horizontal bracings in the net space, supporting the front and lower port walls, as well as small port bracings to combat back and bottom panel resonance. The port ends will be flared as extensively as is feasible, as well as curving the port edges at the port folding. Now I realize from previous critiques that this driver gets the best power handling in a significantly smaller box but from experience with the subs I have been using and from WinISD simulations, it forgoes 50%of its power handling in exchange for increased sub20hz spl/extension in this enclosure design. This appears to be because of its high Xmax and in spite of its very low Qts. In this design the allowable excursion limit is reached at 800 watts/12.5Hz with a 2nd order 14hz HPF. The apparent amplifier power load at that point however is 400 watts. So although the driver is designed for boxes less than 2cuft, it still appears safe in this design volume because of its large Xmax. The box baffle will be doubled (1.5")and the inner port wall will be of 0 . 5 " thickness to conserve internal volume. The feet will four rubber discs and it will be finished in matte black.
I intend to run the four subs with qsc rmx1850hd, two per channel stereo in a 2ohm connection. I hope to get 350-400watts per sub in view of the apparent amp power load simulated. I expect to use them in a 400 cuft sitting room open to an adjoining dining room. So this is what I have come up with, what do you guys think about this before I start building?

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post #2 of 25 Old 08-20-16, 02:17 PM
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Re: Planning Another twin floor standing Subwoofer build

Looks great! Glad to see you designed for HPF, power, and excursion.


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post #3 of 25 Old 08-20-16, 03:10 PM
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Re: Planning Another twin floor standing Subwoofer build

I can't effectively model subwoofer designs, so I'm not able to help you in that area, but I did have a few questions...

Are those pictures of the current subwoofers? And if so, what are they not giving you? It sounds like you want to essentially duplicate them, so I'm curious as to why go through all that work to end up back at what seems like the starting point.

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post #4 of 25 Old 08-20-16, 03:32 PM Thread Starter
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Re: Planning Another twin floor standing Subwoofer build

Thanks for the encouragement. I hope to have the pleasure of getting up to 110 db of 16hz from the quad subs with this minimalist footprint approach. Relatively unobtrusive physical sub presence. This driver is truly incredible, I wish I had more. Check out what appears to be an IB build with this driver
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Planning Another twin floor standing Subwoofer build-attachment-4.jpeg  


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post #5 of 25 Old 08-20-16, 04:43 PM Thread Starter
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Re: Planning Another twin floor standing Subwoofer build

Jim this is a very salient question. Truth to tell,I love the two I have dearly, SQwise I have no complaints. Where I am its really difficult to lay hands on good sub drivers so when I feel the upgrade itch, I naturally turn to drivers I already have. In doing this build I hope to achieve (1) scratching the upgrade itch. (2) get a potential 6db up on the entire FR especially in the sub20s without a difficult-to-blend bulky sitting room presence as well as better room coverage. (3) bury the chuffing I hear sometimes from my subs during intense LFE with fresh additional similar subs having larger ports/lower port airspeed as well as slightly more low extension. With the new subs the 3db FR range should be about 17.5 - 80hz anechoic.

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post #6 of 25 Old 08-22-16, 04:49 AM Thread Starter
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Re: Planning Another twin floor standing Subwoofer build

What I am not very sure of is whether the qsc rmx1850hd has enough power to run the quad subs. Am I correct in assuming that the apparent amplifier load power is in practice the power handling limit of each of these subs inside the proposed enclosure. In other words is the apparent amplifier load power the excursion limit while the Rms power the thermal limit?

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post #7 of 25 Old 08-22-16, 10:22 PM
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Excursion shows you what the sub must be able to take, xmax and xmech, also with the power reference below its RMS thermal rating.

Apparent amp load in VA shows you what your amplifier must sup ply, generally if it's higher than bench tested power then you can expect clipping and should plan for a bigger amp.

In all cases build and try it out if it's close or so. If everything's all in the clear then it will be monster setup....
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post #8 of 25 Old 08-22-16, 10:24 PM
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If you need help modeling your sub setup let me know.
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post #9 of 25 Old 08-23-16, 01:55 PM Thread Starter
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Re: Planning Another twin floor standing Subwoofer build

Sorry for the late reply. Please Russ if you are good with tapped horns and Hornresp I would appreciate it if you can simulate with this driver a tapped horn that has good output down to 10 hz, (I have no clue how to do this) I'm willing to abandon this design in favor of that. Thanks for the offer. That should be a real upgrade.

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post #10 of 25 Old 08-23-16, 07:16 PM
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Re: Planning Another twin floor standing Subwoofer build

Figures! I don't have any experience with horns and have only played with Hornresp...


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