Dual Opposed Sub Build Question

[dougmi78]

Hello all,

Considering building a dual opposed sub for home theater. Using Dayton Ultimax 15". The question I have is would there be any performance enhancement if I used a down firing 18" passive radiator? Legacy Goliath XD uses down and rear firing PR for front firing subs. Just wondering if PR could/should be applied to DO sub set up? Any thoughts welcomed. Thanks!

 

[hudelson2]

A downfiring passive radiator would really sag. The diaphragm is much heavier than a speaker cone. So it needs to be mounted vertically.

 

[poseidonsvoice]

A downfiring passive radiator would really sag. The diaphragm is much heavier than a speaker cone. So it needs to be mounted vertically.

I agree.

In addition, you effectively need 2 PR's (preferably of equivalent diameter to the active unit) for each active woofer. So (2) 15 inch PR's for a single active 15 inch woofer.

My suggestion is to stick with the dual opposed sealed sub design as is, or go with one of the 15 inch Dayton UMS woofers and two of the Dayton RSS 390-PR 15 inch passives in a single cabinet.

See here: YouTube

Dayton Audio UM15-22 15" Ultimax DVC Subwoofer 2 ohms Per Coil

With a little EQ you should be able to have tremendous fun with a dual opposed Dayton UMS 15 inch sealed setup as well.

Best,
Anand.

 

[dougmi78]

Thank you very much for those responses. I was only curious about the potential for performance increase. I can't imagine not getting exactly what I want out of the 2 15" ultimax. I can't wait to build it. My next focus will be wall thickness and bracing. As i research DO builds the boxes have to be very well built or made out of aluminum. Are there any resources that could point me in the direction of a good build design?

 

[dougmi78]

My end goal is to build a complete system with this subwoofer and fronts in a MTMMMMM 3way configuration. Similar to the Burmester BA71. I will use external digital crossover and eq's for tuning because after reading all the posts on here about building crossovers. I will pass all together. I'm certain that I will build a great sounding system for my needs. May not be perfect on measurements and graphs but I think I will love it in the end. On a dayton budget, I am excited to see what happens.

 

[poseidonsvoice]

Thank you very much for those responses. I was only curious about the potential for performance increase. I can't imagine not getting exactly what I want out of the 2 15" ultimax. I can't wait to build it. My next focus will be wall thickness and bracing. As i research DO builds the boxes have to be very well built or made out of aluminum. Are there any resources that could point me in the direction of a good build design?

There are tons. Just google “Dual opposed subwoofer” and you should get tons of hits.

Here is one:

Dual Opposed 18" - Home Theater Forum and Systems - HomeTheaterShack.com

Best,
Anand.