Upgrading my 15's -want opinions

[jonz]

I think you've made a wise choice with the Tempests...


AS for the jBL driver at PE..(the one thats on special) I read the specs and to me this driver would be better suited for a car.

[ratman542]

Originally posted by jonz
I think you've made a wise choice with the Tempests...


AS for the jBL driver at PE..(the one thats on special) I read the specs and to me this driver would be better suited for a car.

Thanks for the opinion, I agree totally. What do you think about the tempests being in stuffed/sealed 3.25 ft enclosures?

I'm not sure how that is going to work out. I am of course considering building new enclosures, but won't do it unless I find the small boxes inadequate.

Also, if you were to choose a box for the tempest yourself, would it be a sealed or reflex?

Thanks in advance,
Rich.

[Tim Moorman]

Kind of like asking if you like blonds or brunettes.

I like them both.

Sealed boxes are my preference, when done well. If the roll off, which is more gradual than ported/vented enclosures, matches the room lift, you can achieve really low bass extension with less group delay - a more natural sound.

But ported boxes can be made to work very well too. And the folks at Adire are quite capable.

The real challenge in any high SPL bass setting is the room. You may find that you will excite resonances, standing waves, and all manner of results you weren't anticipating.

It should be fun, anyway. And stereo subs is a big improvement over mono - more than the sum of the parts. Two help a lot with the room interaction. You may have to scoot them around to find the best location.

Tim

[jonz]

I agree with what Tim said..I would go with sealed..and depending on the power you are running through them you can even go slighly smaller like a 3 cu.ft. with medium to heavy stuffing...and like Tim said,room interaction is very important..with dual subs you have a bit more flexebility in balancing it out...you can try downfiring..turned toward the wall,,or toward a corner..


Ps...when I said slightly smaller ..I'd recommend somthing to the tune of 500 to 700 watts in each in 4 ohm configuration...if not stay with the bigger boxes.

[ratman542]

Originally posted by jonz
I agree with what Tim said..I would go with sealed..and depending on the power you are running through them you can even go slighly smaller like a 3 cu.ft. with medium to heavy stuffing...and like Tim said,room interaction is very important..with dual subs you have a bit more flexebility in balancing it out...you can try downfiring..turned toward the wall,,or toward a corner..


Ps...when I said slightly smaller ..I'd recommend somthing to the tune of 500 to 700 watts in each in 4 ohm configuration...if not stay with the bigger boxes.

I totally understand where you and Tim are coming from. Based on what you both have told me, it would probably be worth loading the Tempests into my 3.2 ft boxes (stuffed & sealed), and see how they sound. Your power recommendation shouldn't be a problem for the TFM-55, especially at 4. If all else fails, new boxes aren't out of the question.

Thanks a bunch for all the advise, I appreciate it.

Rich.

[Tim Moorman]

Ratman.
With a sealed box, adjusting the box size (volume) changes the "Q". Increasing box size lowers "Q". What this means in the overall sound is tighter, drier sounding bass as Q drops (bigger box) particularily below .7, and, naturally, a looser, more full bass note as you approach and exceed a Q of 1.0, with some loss of deep extension.

Your box will yield a Q of around .8 - a little on the full side, a little more midbass tilt. Should sound good, but not the deepest bass alignment. That would require a box of over twice the volume. So, a nice compromise.

Tim

[Tim Moorman]

Ratman,
You will not reach the thermal limits of the drivers until 750 watts are input, however, you may well reach excursion limits before that.
Check with Adire for the details in your particular alignment.

Remember, twice as loud means 10 dB more output, roughly.

Twice the power means a 3 dB increase in loudness (SPL).

Beyond a certain point, additional watts do very little for additional SPL, but quite a lot for compression, distortion, and heat.

Tim

[Cal Weldon]

Hey Rich rat,

I just learned how to quote portions so here goes:

Quote as you have (importing the entire quote) then simply highlight what you don't want and delete it in your actual message. It's that easy. It's also seems proper etiquette to put in a _snip_ to indicate that you have done so deliberately.

Hope that helps and welcome aboard, hope you like this forum. I just discovered it in January and rarely post anywhere else now.

Cheers,
Cal

[ratman542]

Originally posted by Tim Moorman
Ratman.
With a sealed box, adjusting the box size (volume) changes the "Q". Increasing box size lowers "Q". What this means in the overall sound is tighter, drier sounding bass as Q drops (bigger box) particularily below .7, and, naturally, a looser, more full bass note as you approach and exceed a Q of 1.0, with some loss of deep extension.

Tim, I'm still pretty green as far as understanding the "Q" of the different boxes. So if I am understanding what you are saying, in extreme layman's terms, a large "low Q" box (like say a Q of .5) would yield good response way down low and produce a nice warm full low-end (at the expense of power handling due to mechanical limits of the driver), and a small "high Q" box (say something like .9) would not be nearly as warm sounding as the low Q box, but would be much more pronounced in the midbass region and could probably take more power before reaching the mechanical limits? Am I even close? If I understand what you are saying, basically a small box is going to F3 at a much higher frequency than a large box? Is it also true then that the higher the Q gets, the more power will be required to "try" and replicate the the low frequency performance of a low Q design? (ie: small box needs more power?)

Originally posted by Tim Moorman

Your box will yield a Q of around .8 - a little on the full side, a little more midbass tilt. Should sound good, but not the deepest bass alignment. That would require a box of over twice the volume. So, a nice compromise.

So basically the 3.25 ft boxes will end up being slightly above the mid-Q range of .707 (what Adire calls out as being their mid-Q alignment), meaning they will have a little tighter sound than if they were in a larger box with a lower Q?


I am learning a lot here, so please forgive me for asking these types of questions. I find this kind of information very valuable and want to learn as much as I can.

Thank you very much for taking the time to help.

Rich.

[Tim Moorman]

Rich

No problem.

This tuning thing is more like determining flavor, rather than a wrong or right set-up. While I might object to someone using a tuning or Q above 1.0, it being sloppy and less resolute to my ears, it is still just a matter of taste, and particularily where your enclosure Q falls - mid to mid high.

With ported boxes, you adjust the port length to change the tuning. You are essentially resonating the air column which forms in the tube of the port to lift the bass response.

Here we only have the box size (or stuffing) to change for adjustments.
Yes, you can add a corrective circuit or EQ to contour the response, but in high SPL applications you may not have the excursion for this to work.

Tim