Anyone noticed the DPL-15 at Exodus Audio?

[Brian Hinther]

I've been planning to start either a sealed or ported build with a Tempest-X very soon (I was leaning towards ported but having trouble making up my mind), when I ran across this new guy for only $125. They say it's for IB or Dipole use, but it seems to model nicely in a smaller sealed box, too. Here are the T/S parameters:

# Fs: 19 Hz
# Le: 1.6mH
# Re: 6.1 Ohms (Single 8 Ohm VC)
# Qms: 3.27
# Qes: .84
# Qts: 0.67
# Mms: 271g
# Cms: 0.23 mm/N
# Vas: 232L
# Sd: 830 cm^2
# Vd: 3.65L
# BL: 15
# X-max: 22mm
# X-mech: 29mm
# Pmax: 600W
# 85dB/1W/1m

I tried starting this thread on another forum, but couldn't generate much interest. I realize I'm comparing apples with oranges, but I was figuring I could put two of these in a sealed box for not a lot more money than one Tempest-X and push more air.

I'm just a newbie looking for feedback because I'm probably missing something. And I wouldn't mind hearing opinions on whether the Tempest-X would be better suited to a sealed or ported build. I guess what I really need is to settle on something and get started!

Thanks for any help you can give me.

[Mazeroth]

They say it's for IB or Dipole use, but it seems to model nicely in a smaller sealed box, too.

# Qts: 0.67
# Vas: 232L

I think maybe you forgot to type in that last 2 for the Vas into your box modeling program because this sub is going to require a beast of a box. We're talking 10+ ft3, sealed.

[Brian Hinther]

You're right about the size--BassBox Pro says about 12.5 cu.ft. for a .707 Q, but for two woofers that doesn't seem outlandish to me. Maybe that's because I've been working with the Tempest-X, which also likes big boxes--especially ported.

Any other thoughts?

[Mazeroth]

You're right about the size--BassBox Pro says about 12.5 cu.ft. for a .707 Q, but for two woofers that doesn't seem outlandish to me. Maybe that's because I've been working with the Tempest-X, which also likes big boxes--especially ported.

Any other thoughts?

More than likely that's 12.5 ft3 for a single subwoofer.

[Jack Gilvey]

Hence the lack of interest, it's really for IB or dipole where the high Qts is a benefit.

[Dennis H]

I don't know what's wrong with the BassBox calcs. For Q = .707, ISD online says 72 cu.ft. for one driver or 144 cu.ft. for two drivers, and that sounds about right. The driver in an IB is .67 so you aren't going to have to going to have to go a lot smaller than 'infinite' to bump the Q from there up to .707.

Edit: I think Mazeroth is probably right. If Vas is off by a factor of 10, you get something like Brian's box size.

[Brian Hinther]

Oh My Gosh!

I see what you mean. While BassBox Pro is recommending a measly 243 liters for one of these, UniBox is saying over 1,000 liters. Even the little Sealed program is in there with 2,000 liters. WinISD does seem a bit extreme, by comparison, suggesting 7,500 liters.

Maybe it's the high Qts that makes these programs react so differently? Or maybe BassBox Pro isn't nearly as good as I thought.

Anyway, thanks for pointing this out. The DPL is definitely off the table, and I'm back to deciding between sealed and ported for the Tempest-X.

[Jack Gilvey]

Maybe it's the high Qts that makes these programs react so differently? Or maybe BassBox Pro isn't nearly as good as I thought.

It's much more likely the specs were input incorrectly for it to be so far off. All these programs use pretty much the same math.

[Dennis H]

As Jack said, they all use the same math. Unibox probably isn't agreeing with WinISD because of the various default inputs: Ql, Qa, series R, etc. Where the raw driver is close to Q=.7, small changes in any of those will give a big change in box size for a .707 design. I don't know anything about the other programs but I know Unibox and WinISD use different defaults but let you change them to whatever you want.

[its_bacon12]

Looks like it may be ever so slightly better for displacement/LFE than an AE IB15

[Brian Hinther]

It seems like most of you guys think I'm an idiot, (and I've been accused of that before), but I don't think I'm the problem in these discrepancies. I've posted a jpeg of the parameters copied from each of the three programs we're discussing (along with their results) rearranged to make comparison easy, and I can't see that I did anything wrong.

The only thing I can see is that the website didn't specify their BL rating and I used Tm instead of N/A, which I probably should have done.

I have to go back to wondering about the high Qts issue, especially after reading Zaph's latest blog entry. He's talking specifically about the Dayton RS 100 with a Qts of .8 and small woofers in general with a high Qts when he says:

"The concern is when people enter these T/S parameters into a typical box response program and ask for the optimum size. It might be WinISD, Unibox, some online app, or whatever. The problem is that these programs are not smart enough to make decisions for the real world with design limited drivers."

He goes on to say, "...most brainless box response programs will recommend a too-large box... People need to realize that smart, real world enclosure design requires more than what most of these box response programs provide."

Now, maybe most of this doesn't apply to what's going on here, and maybe I am an idiot, but it makes me wonder what SoundEasy or LspCAD would do with the DLP-15.

Also, I would welcome more input on changing the defaults on these programs (especially UniBox) to make them play nice together. At this point I'm not very impressed with BassBox Pro or WinISD.

By the way, the attachment comes up looking pretty nasty in my browser, but if you'll copy it and paste it into your favorite image-editing program and view it at 100%, you should be able to read it.

[ThomasW]

IB/dipole drivers have smallish motors, smallish VC's and lower power handling because these drivers are excursion limited, not thermal limited like drivers used in boxes. Also their very high Vas makes using them in a traditional box somewhat unrealistic.

As far as the box programs are concerned I've found UniBox and LspCAD provide similar results, but it's never dawned on me to model an IB/OB specific driver for a traditional box.

[Brian Hinther]

... but it's never dawned on me to model an IB/OB specific driver for a traditional box.

Thanks for being kind, Thomas. I think I'm starting to get it now--something about a fool's errand? I guess I just didn't realize the speakers were that different. I mean, they're both 15s, right?:rofl:

Seriously though, sometimes when I'm about ready to order something, I have to flail around a little to make sure I've considered all the options. I'm now back to a sealed Tempest-X for my first build. Thanks for helping me get there.