Can you just swap out a Tempest w/ an AV15 for better performance? (1 Viewer)

[Steve Stogel]

This is just so very sad. I just sold my SVS to help towards the purchase of Mark Hayenga's DIY Tempest sub, which I have yet to actually pay for or pick up yet. Anyway, it's a 270L Tempest with dual 4" flared ports. Here's a link to the build process:

http://hayenga.com/mark/speakers/tempest/tempests.htm

What I was wondering is if swapping out the Tempest w/ an AV15 down the line will give me noticeably better performance.

The reason I ask is right now I have a 150w sub amp. I will want to upgrade that in the near future to squeeze every ounce of bass I can out of the Tempest. The Tempest, however, in that enclosure can really only take about 250w from what I've researched. So I can just get a plate amp and get all I can from the Tempest. But what I'm leaning towards is getting something like the QSC RMX850, which will give me 300w into 4 ohms per side. Perfect for the Tempest now (using one side), and if I can swap the Tempest with an AV15 down the line, I can run it bridged, which puts out 830w into a 4 ohm load. I know Mark, Jonathan, Hank, or a slew of others here in Austin could probably answer my question, but I just figured I'd throw it up to the entire board. Thanks, guys.

Steve

 

[Ryan Schnacke]

Looks like you'd gain 2dB by upgrading to the 250 watt amp. Or you could gain 6dB by substituting the AV15 and 830 watt amp.

The AV15 in that enclosure looks pretty darn flat. There's a tiny dip (1/2 dB) around 35Hz that indicates a high-Q alignment. Group delay spikes up to 40ms near tuning - that confirms the hi-Q alignment. But the important thing is that group delay stays under 20ms to 25Hz and the freq response is pretty darn flat.

High-Q alignments are okay in ported enclosures where you can push the tuning frequency down near or below the Fs of the woofer. EBS alignments are a good example of this.

So you just need to decide if you want to spend
$120 for 2dB gain from the 250 watt amp
or
$205 + $??? for 6dB gain from the AV15 and QSC amp

Dollar-for-dollar the Tempest is probably the better deal and may even satisfy you with "only" 150 watts. The AV15 will always have more ultimate output potential.

 

[Steve Stogel]

Thanks for the response, Ryan.

So is it fair to assume that in that box, the Tempest and the AV15 would give similar if not identical response up to the Tempest's limits? In other words, with 300 watts, similar performance...with 600 watts, the AV15 gives you 3dB more and the Tempest explodes?

What confuses me is when people talk about how much air a driver can move (I obviously know nothing about speaker building). I've seen numbers on the Tempest of 2.55L per stroke, I think, and 3.8L for the AV15. That gave me the impression (perhaps incorrectly) that even at 300w, the AV15 may be moving more air.

If this is correct (the paragraph starting with "So is it fair"), then a good 300W amp will give me 2-3dB more headroom than my 150W amp (and push the Tempest right to its limits), and I can probably only get an extra 3dB or so with an AV15 over a Tempest by adding an additional 300w (600w total) or so. Does that pretty much sum it up? Thanks for the info.

Steve

P.S. But the AV15 is soooooo pretty. My wife would let me upgrade just for the looks.

 

[Steve Stogel]

BTW, as far as the cost...


It would basically shake down like this:

Xdb and keep the 150w amp.
XdB+2 for $120 (PE 250w plate amp)
Xdb+5/6 for $420ish (220 for the AV15 less the 100 or so I can get for the Tempest, plus $300 for the RMX850 or similar amp).

Boy, I sure hope the Tempest and my amp get me 95% of what I want so I can just get a decent plate amp and have a little more headroom. Thanks again, Ryan.

Steve

 

[Jack Gilvey]

If this is correct (the paragraph starting with "So is it fair"), then a good 300W amp will give me 2-3dB more headroom than my 150W amp (and push the Tempest right to its limits), and I can probably only get an extra 3dB or so with an AV15 over a Tempest by adding an additional 300w (600w total) or so. Does that pretty much sum it up?

Things are never quite as simple and predictable as the simulations lay out, although the above seems a reasonable estimation. Basically, the AV15 and more power will get you lots more bass. I found the AV12 to be a worthwhile improvement over a Shiva in the same alignment with the same power applied, though, so the same may apply to a Tempest/AV15 swap. And if your wife likes the looks, you're home free.
Do give the Tempest a whirl first, though, it's all most people need.

 

[Jeff Meininger]

Steve: the AV-15 IS so pretty. I'm going to downfire mine in a sonotube, which seems like a darn shame since you'll have to lie on the floor to see the cone in all of it's wildly excursing glory. I'd rather build a PR sub, but current time and money limitations pretty much nix that for now. Maybe some day.

I've heard (experienced?) Mark's "Compensators". They're darn impressive. I agree with Jack... give yours a shot as it is before deciding if you need more.

I'm going to have my PE 250W plate amp up for sale very soon now if you want it. I even built a little box for it. It should go quite nicely with that tempest sub and let you get more out of it. After calibrating your sub's baseline level gain where you want it, I think you'd be more at risk of clipping the 150W amp during a loud explosion or something.

By the way... are you getting the black "compensator" or the red one?

 

[Steve Stogel]

Thanks for the responses, guys.

I definitely plan to give the Tempest a good evaluation before I decide if I need/want more bass. I've got an extremely open floor plan. It's something in the range of 8000-10000 cubic feet, I'd guess, because the whole house is basically open not counting the four bedrooms and utility room.

My single SVS 25-31CS (original driver, to boot) w/ the 150w amp could get me up to around 101-103 dB on bassy scenes even with all that space. I'm hoping to creep up somewhere near 108-110 with the "compensator" (never heard their names before). I figure 111-114, perhaps, with 300w, and maybe 114-117 w/ 830w and an AV15 swapped in.

All this, of course, is completely theoretical, and since I'm the only one in the house that felt the bass was lacking (at very high levels), it may be an uphill battle to do the upgrades. But with the looks of the AV15 and the front firing, exposed-woofer design of the "compensator," I think upgrading to an AV15 down the line would not only be accepted by my wonderful and understanding wife, but encouraged. She definitely liked the looks of it. Instead of selling the Tempest, I could always just keep it as insurance or my own project down the line.

And, Jeff, I'm getting the red "compensator." Not the one I wanted, but the only one left. I'll definitely have to figure something out. Hopefully Mark or Jonathan can show/tell me how to make it black. Definitely email me once you sell your PE 250W amp, as I would most likely be interested. I also saw you may be selling one of your DIY subs down the line, and my bro-in-law or someone else I know may also be interested in that.

Steve

 

[Ryan Schnacke]

You're welcome Steve. Sorry I'm so slow, but they cut off our internet access at work. But it looks like the real sub experts showed up to help you out. These guys know what they're talking about!

 

[Frank Carter]

Steve,

If you do later decide to switch out to the AV-15, may I suggest seeing if you can fit another 4" port.

 

[Steve Stogel]

Thanks for the suggestion, Frank. So three 4" flared ports with an AV15, ya think? That would probably not be doable as the "compensator" has the tempest front firing, centered on the face, with a 4" port above and below it. Would that likely just give a bit better performance, or will two 4" ports be more likely to produce port noise w/ an AV15 in there?

Steve

 

[Jeff Meininger]

Would that likely just give a bit better performance, or will two 4" ports be more likely to produce port noise w/ an AV15 in there?

Less port noise with 3 ports? Definitely. Better overall performance with 3 ports? Maybe, maybe not.

Adding a third port will decrease vent mach, or airspeed in the port(s). Decreasing vent mach obviously reduces port noise, and it also helps performance by decreasing problems brought about by "port non-linearity". The more power you run apply, the more "port non-linearity" has a negative impact on your low frequency response curve.

However, the addition of a third port will require that all ports be lengthened to keep the tuning frequency the same. First, they might not fit. Second, a port that is too long can create unwanted resonance. Third, more ports means more port wall surface area which means more resistance is experienced by the air flowing through, which means more potential output is lost.

So, just two 4" flared ports isn't exactly ideal for an AV15. Heck, I got reprimanded not too long ago for using a single 6" straight port (greater than the sum of two 4" ports) without using flares. Considering your options, though, I'd stick with the dual 4" ports even if you dropped in an AV15. The third port's benefits and drawbacks would cancel eachother out, IMHO.

I take it you don't like the red velvet and are trying to decide on another finish. If you're looking for a cheap/easy covering material, I highly recommend the PE vinyl. Doesn't look anywhere near as nice as veneer, but it's not ugly either. And SO much easier than painting.

 

[Steve Stogel]

I'll look into that, but I belive Mark mentioned to me a while back that he may even have some spare black material I may be able to use. I liked the black look a lot, but "black beauty" was sold first, so I'm getting the "righteous red retaliator"

Steve

 

[Steve Stogel]

Thanks again for the suggestion, Jeff, but that's probably already out of the running as Mark rounded the edges on the compensators. A very nice touch, but probably rules out the PE vinyl. So black velvet, here I come. The red color has already started to grow on me (probably more to do with the sound than the actual color), but I think it may never grow on the missus. Hope to see you guys Friday.

Steve