New Subwoofer Design

[Ray Collins]

I need to build two subs to use as end tables on either side of my couch for HT application in a small room(13'x14'). The bipole configuration seems best since items can remain on them during use without "walking." John Krutke's RSS315HF based sub design seems an excellent starting place and would need to be doubled to accomodate a second driver. Additional adjustments are obvious and include omission of the plate amp among other things. The numbers that I have generated are as follows:
Dayton RSS315HF Fs=24.74 Qts=0.44 Vas=3.0 cu. ft.

External Dimensions H=24" W=14" D=26.75"
Internal dimensions H=22.5" W=12.5" D=26.75" 7523.44cu." or 4.375cu. ft. nominal value
Driver volume = 208cu."( 104 cu." ea. x 2)
Two Shelf Braces = 207cu."(426cu." + 211cu."= 637cu." less 430cu." for holes.)
Second Baffle = 211cu."

Total adjustment= 626cu."

Net Volume = 4 cu. ft.

Material is 3/4" plywood and 3/4" MDF for the baffles.

Comments?

Ray

[ThomasW]

It's only drivers with very high Xmax being driven at high SPL that have the tendency to 'walk' the cabinet.

Mounting the drivers on opposing sides will cut down on the mechanical vibrations, and that's good for end-table subs.

Expanding the design for a pair of drivers will work fine. Were it me I'd use an LT circuit to lower the Qtc. The decision to do that can occur after they're built.

So sounds like a great project.... :T

[Dennis H]

For more output, two of the 15" RS HO in anything over 3 cu.ft. model great. They do need EQ to boost the low end. I think Brian Bunge is doing something like that.

[Ray Collins]

Thomas and Denis:
Your interest and input is greally appreciated; of the three forums upon which I posted my questions yours are the only responses showing an interest in helping. I realize that this is a very simple speaker and beneath most DIY'ers but as Marco Polo said "every journey begins with the first step". Thanks for the guidance.

Thomas,
I will need to purchase an amplifier and an EQ device. It appears that the EP2500 and the DEQ2496 are somewhat standard choices?

Denis,
I am limited to a maximum baffle width of 14" due to space constraints so unfortunately the 15" drivers will not work in this application.

I have read InPHASE's 4 15" sealed sub project thread several times which provided a great deal of insight. I hope mine will be as successful.

Once again, many thanks and any input will be welcomed.

Ray

[---k---]

Ray,
It sounds like you are about there. Without seeing the model, I can comment much. If you have a model that you could post, I would love to see it.

I'm assuming that you are going to use multiple layers on your baffles, it wasn't clear. What is your thinking that you're going to use MDF on the baffles and plywood everywhere else?

[ThomasW]

Ray,

For this particular project you won't need an amp as powerful as the EP2500, but given the minimal cost difference between it and less powerful amps, you might a well get it. If you don't want to deal with fan noise buy the BKA-1000-4A

Yes you'll want a more sophisticated form of EQ than say the BFD. So go with the DEQ2496. Also buy the Behringer ECM8000 mic. It plugs into the DEQ for quick and easy measurements.

[Ray Collins]

---K---
I did all of the calculations by hand after reading the Weems and Dickason books so I do not have a model. I then searched until I found a similar design which was Zaph's RSS315HF sub. I have attached his model which I assume will be similar.
I intend to use 3/4" plywood for the sides, top and bottom of the box and 3/4" MDF for the baffles. The baffles will be doubled with the inner baffles flush mounted inside the front and back of the box and the outer baffles bonded to them. The plywood will be finished in a dark mahogany while the MDF will be painted black and either chamfered or rounded over. The box will employ mitered joints to hide the end grain, increase the glue surface and appease the WAF.

ThomasW
Thanks for the suggestion regarding amps and the EQ unit. The BKA1000-4A's lack of fan is appealing; is it capable of running both of the bipole subs?
The DEQ2496 and microphone sounds fine. I assume there is a manual with clear instructions on use or either some clever lad has posted a "how to do it" site?

Thanks again for your interest and guidance.

Ray

[---k---]

Sounds nice.

The DEQ2496 and microphone sounds fine. I assume there is a manual with clear instructions on use or either some clever lad has posted a "how to do it" site?

Ray

Heehheheh. No, but we're here to help. Several of us have the DEQ2496.

I have the mic, and have plugged it into the DEQ once. It will only automatically set the Graphical EQ, not the PEQ. I also found the scale on the display small. This to me limits its usefulness. So, I own a MAudio Mobil PrePro external soundcard which allows me to plug the mic into my laptop and take good measurements. But, you don't need to jump in with both feet, YET.

[Ray Collins]

Well it has been an opiat thus far so I am sure that in the near future both feet will be in.

Many Thanks fellows; I remain open to any guidance.

Ray

[ThomasW]

The BKA1000-4A's lack of fan is appealing; is it capable of running both of the bipole subs?

With ease.... :T

The DEQ2496 and microphone sounds fine. I assume there is a manual with clear instructions on use or either some clever lad has posted a "how to do it" site?

That's a work in progress....

http://home.comcast.net/~thomasw-2/SubwooferSetupandEQpageDEQ2496.html

http://home.comcast.net/~thomasw-2/SubwooferSetupandEQpageDEQ2496-LT.html

[Ray Collins]

The DEQ2496 is quite an impressive problem solver; just the item for a dilettant designer like me...assuming I can master it. Very generous of DennisH to author this guide. Thanks ThomasW for the heads-up.

I assembled my new Bosch table saw this weekend and will begin work on the subs tomorrow unless my wife persuades me to take her to the gaming casinos and Mary Mahoney's for gumbo and crab legs...

Ray