WinIsd : Cone Excursion

[Frostedflakejake 148]

So I found out today that the version of WinIsd I had been using became obsolete ages ago 

Trying to model a JL Audio 15w0v3 and I'm skeptical of the cone excursion graph it's showing. Considering I modeled the thing in a 15 ft³ box tuned to 15hz I was expected cone excursion to at least get higher than 1.5mm on 500 watts. I feel like I've done something wrong but for the life of me I can't figure it out! I'm confident all the driver parameters I entered were correct..

 

Any insight as to what foolish thing I'm doing wrong? 

 

Thanks!

 

 

Edited September 17, 2013 by Frostedflakejake

[lithium 358]

edit nvm, my version is way out of date

Edited September 17, 2013 by lithium

[Frostedflakejake 148]

Thanks anyways!

[Quentin Jarrell 671]

I'd relook at the specs.  BL of .5?  And a Cms of .16mm/N ?

[Frostedflakejake 148]

I'd relook at the specs.  BL of .5?  And a Cms of .16mm/N ?

 

Those got calculated by WinIsd once I entered in no and SPL specs.

As long as SPL is the same thing as what JL calls efficiency, then all the values in green are straight from JL's website. The blue ones WinIsd all calculated 

[Quentin Jarrell 671]

They are way wrong.  The BL is obvious.  The Cms is how much force it takes to move the cone.  The Cms show would be a really really stiff subwoofer

[Frostedflakejake 148]

They are way wrong.  The BL is obvious.  The Cms is how much force it takes to move the cone.  The Cms show would be a really really stiff subwoofer

 

Alright then... Any advice on how to carry on? I suppose I'll e-mail JL and try to get a more thorough list of specifications. 

 

Thanks!

[Frostedflakejake 148]

Alright well thanks to this page http://en.wikipedia.org/wiki/Thiele/Small i calculated a cms of 0.163779mm/N  and a BL of 17.0211 Tm

 

Does that sound a little more reasonable? I triple checked my calculations

[Quentin Jarrell 671]

based on the moving mass (which the program calculated) .163mm is corect and might be close.  I had my decimal places wrong.  The Cms on my Ethos is ~56uM per newton which is .056mm.  So .163 being ~3 times as loose would seem about right

[Frostedflakejake 148]

Is moving mass mms? I calculated mms as necessary to calculate cms and got the same .2593 kg as the program

[Quentin Jarrell 671]

yea, Mms is the moving mass with the air load.  That's probaly close.

[Frostedflakejake 148]

Anyone know how I can high pass filter this at around 15hz? I already know about the MiniDSP; it's just a bit expensive considering I only plan on using it as a highpass. Looking for something a little more like a Reckhorn B-2, but I can't find anywhere online that will ship them to the states. And the Reckhorn even has more features than needed but it's still cheaper than a MiniDSP and little more user friendly.

 

Advice?

[S.DeYoung 967]

Why 15hz? Are you worried about content under 15hz? What are you using to power the woofer?

[Frostedflakejake 148]

Why 15hz? Are you worried about content under 15hz? What are you using to power the woofer?

 

That's a good point. It's a home theater build and I read elsewhere in the home theater section that I should try to tune in the low teens and that a SSF is absolutely necessary; and after looking at my cone excursion plot I can see why!

 

The amp is a Bash 500w plate amp. They do not explicitly list the frequency range of their amp on the parts express website. I assumed that the nature of this device would imply a frequency range down into those levels.

[///M5 2,833]

The reckhorn is awesome, wish I still had mine.

In Germany right now....with more warning I could have brought one back

[Frostedflakejake 148]

So the MiniDSP is cheaper than I thought... using their product selection guide I'm lookin at the MiniDSP 2x4 with the 2-Way advanced 21 software. 

 

I don't know if i should start a new thread or not for this; but I was looking for some help with my receiver. I have a Yamaha R-V503 that I got at GoodWill for $6. I currently only use it in stereo configuration. I'm just trying to figure out the voltage of their pre-outs so I can choose the appropriate input jumper for the MiniDSP. I should just be able to take a voltmeter in Vac to a wire connected to the subwoofer preout and then convert the answer to rms; right? I guess i'll go out and buy a 9v battery so I can try this method with my second DMM because I'm reading nothing and it definitely works. 

[Frostedflakejake 148]

The reckhorn is awesome, wish I still had mine.

In Germany right now....with more warning I could have brought one back 

 

It was actually your posts that pointed me towards it. 

Thanks for the offer! That's awfully kind of you.

[///M5 2,833]

I don't follow the 9v battery thing above.  Just play a 0dB test tone at 40Hz (or whatever bass tone you have that isn't super low) and play it through the receiver, plug in your DMM to the outputs of one RCA (inner pin and outer shield), set it to AC and measure the volts.

 

Or just buy the higher input miniDSP because it is what you will need.  (and if you don't you can always open it and flip the switch).

[Frostedflakejake 148]

I don't follow the 9v battery thing above.

 

I just needed one to power my second meter; that's all. I have the feeling my one meter isn't all that accurate at low AC voltages. 

 

The MiniDSP 2x4 unbalanced should be what I want, right? 

 

While you're around Sean, I would like to pry at your knowledge if you don't mind. This build is solely for home theater. I'm having a rough time with box design because I'm unsure of how important output below 20hz is. I can't seem to get a flat response in a realistic box size when I drop my tuning below 20hz. An example is shown below. Both plots have HPF applied to limit cone excursion to the safe range. Green plot is about 10cubes at 20hz and pink plot is 15cubes at 15hz. As shown, the output of the pink plot below ~18hz is significantly larger than the output in the same frequencies of the green plot. 

 

I'm trying to reason if this outweighs the fact that the green plot is so much flatter. 

 

 

 

[Impious 1,476]

Rooms have "cabin gain" (in this case it's called room gain) the same as a car....albeit not as extreme in amplitude and not over such a wide bandwidth.....it's more low frequency oriented.

But moral of the story is that just like with a car, flat anechoic (I.e. WInISD) is not flat in a room.

There is a reason EBS alignments are very popular, which is about what you have there with pink graph.

[REVpuggie 23]

M5 you've looked @ Hypex plate amps ? since you're in Germany 

[///M5 2,833]

The tuning question is a good one.  Car audio and home audio are completely different due solely to the environment.  This is compounded if you are interested in a home theater setup as well as movies have ultra low frequency content.  I am a little jet lagged, but my memory says you were looking for both in which case a rather large box with a tuning in the low teens is appropriate.  It is easy to see where tuning lower starts to buy you nothing in the cone excursion page.

 

 

M5 you've looked @ Hypex plate amps ? since you're in Germany 

I flew home yesterday.  Just doing a quick visit to our manufacturing facility and a stop by Mercedes NVH Engineering to help them with a couple things.

 

 

[Frostedflakejake 148]

Holy cow, it's been a month. So I finally started this today! My space is a little more limited than I would like and my tuning is a little higher than I would like, but I'm interested to see how it performs regardless. I won't be living in this home for too much longer anyways!

 

Net volume will be around 13 cubes and tuning will about 16hz. 

 

I tried to be proactive and get the local lumber supply to do one of my cuts for me. Boy was that a mistake! I can do a better job with my jigsaw than they did with their planar saw; and i'm not very skilled even. So that will unfortunately slow me down. 

 

With two six inch round ports WinIsd gives me a maximum port velocity of 9 m/s which seems low to me, but I'm happy to oblige! A slot port would kill my net volume anyway. 

 

Now just to figure out this MiniDSP stuff...

[Frostedflakejake 148]

Some progress pics. Keeping a more detailed build log here: http://www.homeaudioforum.net/topic/664-jl-15w0v3-and-bash-500w-plate-amplifier/

 

Edited November 14, 2013 by Frostedflakejake