Stryke AV15 PR (1 Viewer)

[ArthurJ]

Im not too worried about Brok fee's, but your right, it is actually more of a bargain to get the tumult in canada then it is in the states...I can get a single tumult for $600 Shipped.

Is an LT absolutly neccessary? And is it only for sealed enclosures? thanks!

 

[John E Janowitz]

Hi Arthur,

Let me start with your questions in the original post. The AV15 and dual 18" PR's in the 24" cube would match output with the original Power15 sub I sent to Tom Nousaine. The AV15 has a little less excursion capability, but more cone area, so volume displacement is about equal. Check out the list Frank Carter put together of subs Tom Nousaine has measured to see how it comares to commercial subs.

http://www.hometheaterforum.com/htfo...hreadid=154360

Now, comparing a single sub with dual PR's to a pair of sealed subs has a few tradeoffs. The single PR sub will extend much deeper without any need for EQ. You get response down to 17hz or so. Below 30hz or so the single PR sub would actually give you more output than a pair of sealed 15's. It all has to do with the volume displacement. Each woofer displaces about 3.8L of air. A pair of sealed subs would displace about 7.6L total. The PR sub has a pair of 18" PR's that each displace close to 9L of air at full excursion. Add that to the displacement of the woofer in the box and the single PR sub has about 2.5 times the displaement of the pair of sealed subs.

From 25hz down, the dual PR sub will outperform the pair of sealed subs. Above that point the sealed subs can outperform the single PR sub. The choice depends on whether your goal is to play lower or play louder.

As far as sound goes, the PR aligment is tuned to 18hz. The lower you tune, the more "tight" and "accurate" things begin to sound. The lower you tune, the closer your group delay and phase response get to that of a sealed system.

An LT can get you flat response down lower with the sealed box. The only thing is that you are still limited to only the displacement of the single woofer. No matter how you look at it, the PR's move more air and will allow more overall output. Whether you need that extra output or not is up to you.

I don't want to get into much of a comparison with the Tumult, but the same applies as above. The more air you move, the more output you get. A pair of AV15's displace 7.6L. The Tumult displaces around 5.4L.

With regards to matching woofers to mains, it is very rarely an issue with the woofer itself. It is must commonly due to placement and/or crossover and phase settings.

John

 

[ArthurJ]

Wow, thanks John, that put's a lot of my questions to rest. My goal is Reference levels for theater with good sound quality for music.

"A pair of AV15's displace 7.6L. The Tumult displaces around 5.4L."

This would be with them both in there sealed enclosure right?

 

[John E Janowitz]

That was just the amount of air the drivers alone can displace. In a sealed enclosure your output capability is directly proportional to how much air you can move.

In a vented/PR box it becomes more complicated because you also have to figure in the amount of air the PR's or port move.

John

 

[Brian Bunge]

Arthur,

A driver's Vd (volume displacement) if irrelevant as to what type of enclosure it's in. If you want reference level bass then a low tuned PR based sub is probably your best bet. I'm not sure if you'll be able to achieve reference levels or not. What size is your room, is it completely sealed off from the rest of the house, etc.

 

[ArthurJ]

Brian, My room is medium large. Is your Tumult using PR's?

 

[John E Janowitz]

Arthur, do you have dimensions on the room? Medium large to some people could be a lot different. Based on most people I've dealt with, medium large to me would be something along the lines of 18ft wide, 24ft deep and 10ft ceiling. To others that alone may seem like a very large room. To others it may seem small.

John

 

[ArthurJ]

John,

My room is approx 17x12

 

[ArthurJ]

John,

I see your polish...

 

[Brian Bunge]

Arthur,

My Tumult is in a 53L sealed enclosure with a LT circuit and a Crown K2.