Dual 12" sub dual PR flat response curve (1 Viewer)

[Bstloukal1]

Working on designing another enclosure which will consist of dual 12" subs and dual PR's. after a lot of modeling I'm showing a really flat response from around 20hz to 32hz. Not having really worked with having to fix a response like this what suggestion would you have the response is low about 8db at 20hz and drops down to only about 3db at 32hz. If an eq inline will help let me know what suggestions you may have. I haven't been building long but this is a pretty flat curve that I want to be able to work out before I begin the build I don't believe it's a big deal to fix but need a little help thanks!

 

[Bstloukal1]

 

[Bstloukal1]

as you can see a flat resonse from 20hz. ideas?

 

[Bstloukal1]

 

[Bstloukal1]

ok played around a little more. The PR side says that is tuned to 11hz were the box is at 22.3hz the graph is looking better but what suggestions would we have to lower the freq tuning and keep a good curve After some playing around this is about the best i have come up with.

 

[Robert_J]

The software can't predict how the sub will interact with the room. It's all a guess unless you measure your room.

 

[Number1AVdork]

Give it a shot. All the software in the world won't tell you how well it will perform in your room.

 

[Robert_J]

Choose a design that fits your size requirement and gives a decent response curve and then build it.

 

[Bstloukal1]

Yeah. That's what I was looking at doing. I am planning on doing a 5 cubic as that seems to model up the best. I will make adjustment after its done and I get some readings if needed. I'll keep posted as I plan on documenting this build as it should be an interesting one for me.

 

[Robert_J]

What PRs are you using? Are they adjustable?

 

[Bstloukal1]

the PR's are adjustable they are the VMP 12's.

 

[Robert_J]

Mount them inverted and adjust the tuning until you find what you like.

 

[Bstloukal1]

Not working with PR's before am I looking for something specific. Am I looking for when Xmax is reached when a certain weight is added or am I just looking for what I think is best and then do some measurements?

 

[Robert_J]

Am I looking for when Xmax is reached when a certain weight is added

You shouldn't be close to xmax on the PRs. That's why you always have at least twice the displacement of PRs when compared to the driver.

am I just looking for what I think is best and then do some measurements?

Yes. The simulations will get you close but after that you can fine tune the sub by changing the weight of the PRs. Compared to ported boxes, PRs are expensive but this option is sometimes worth it. I have some older Stryke Audio PRs that I have never unboxed. I need to do that soon.

 

[Bstloukal1]

Nice on the stryke PR's. Here is what i am looking at doing i am planning on using a tone generator to make the tone I want to tune the system to.. Let's say 18Hz. I'll play the 18Hz and then add weight until the PR reaches it's peak excursion? Can i use an impedance meter to verify this? Or should i just eyeball it as the frequency play stays the same .

 

[Robert_J]

Finding max excursion is difficult to eyeball. Also, most meters measure resistance (DC current) and not impedance (AC current) so it will be difficult to find the impedance at the specified frequency. On the other hand, Woofer Tester from Parts Express does a great job with this.

 

[Bstloukal1]

is this the item. http://www.parts-express.com/pe/showdetl.cfm?partnumber=390-806 thanks

 

[Robert_J]

That's it. Same hardware as Woofer Tester 3 but much better software. Either one will work for a sub. And impedance sweep takes about 2 seconds and gets you to 1/10 of a hz accuracy.