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Old 29th April 2013, 04:17 PM   #11
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One more note - as long as you have people that don't understand or care about the system's limitations running the show they will continue to blow stuff up. Even if you give them subs capable of 180 db @ 2 hz. That's life and there's not much you can do about that.
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Old 29th April 2013, 09:03 PM   #12
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Quote:
Originally Posted by just a guy View Post
I
6. Using the same drivers and same overall cab size (net) it took me about 3 minutes to beat the snot out of your sim. If you get a bigger amp and assuming the drivers can handle the extra power I can beat it by quite a bit.

Graph 5 (line 3) - direct comparison of tapped horn vs flh, 3 cabs of each
Just a guy,

The increase in sensitivity above 30 Hz the FLH shows would be a good thing.

Even though the sim shows double the power can be put in without exceeding Xmax, much of that increase would go to heat and power compression.
When things get "out of hand", most EDM drivers fail from thermal, not mechanical problems.

Since the TH already is around Pmax at Xmax, and with EDM one does not want to exceed Pmax, the FLH looks to be around + 2-3 dB in the 80 Hz range over the TH, a good improvement, though I'd be hard pressed to say that is "beating the snot out of" the TH sim.

Also, if using PP as the OP seems to want, one driver would be at a serious heat disadvantage in a FLH, the tiny chamber would be like an oven in a couple songs, reducing the +2-3 dB advantage further, real world might be only half that.

Art
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Old 29th April 2013, 09:35 PM   #13
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You bring up some good points, all of which I was going to address if the OP showed any interest. I was also going to bring up another point as well. Since the flh needs a much higher high pass (about 10 hz higher) that will take a bit away from the flh sim around tuning and the only way to get that back is even MORE power.

To address the power concerns head on, I've never burned a sub. Ever. Even when I try to reach pmax and xmax at the same time in my sims it ALWAYS sounds bad long before it burns. Even when I exceed pmax before hitting xmax in my sims it ALWAYS sounds bad before I have thermal issues. In other words, I've always had excursion issues and never thermal problems. Now if you have a clueless dj that keeps turning it up well past the point that it starts to sound bad that's another story completely...

My sim is shown at 3500 watts rms per cab (875 watts per driver). The drivers are rated at 500 rms (2000 peak) and I think they could handle the power I've shown them at with minimal thermal compression. As you pointed out awhile back, assuming fairly dynamic music the drivers only get a fraction of the amp's full output capability most of the time.

Chamber size in this design is 200 liters. This is almost 5x larger than the Labhorn rear chamber. This design has twice as many drivers though, so cut this larger design in half and then driver for driver it's almost 2.5x larger than the Labhorn rear chamber. To be painfully clear, the Lab has about 21 liters per driver and this design has 50 liters per driver. Also, this design is tuned almost an octave lower than the Lab, which means much more cone movement, which equates to a lot more fan action cooling the coils.

The Labhorn is obviously not the best example of a thermally controlled environment but compared to this design they are not even close. You have almost 50 percent more chamber PER DRIVER in this design compared to the Lab and a lot more cone movement to help cool the drivers. So I don't think calling the chamber "tiny" and "an oven" is really fair. Besides, the chamber could be increased by 25 liters without causing any problems but I didn't do that because I was trying to keep it the same size as the tapped horn sim presented in post #1. Also, the design could be tuned even lower than shown, requiring a much larger chamber if that was desired.

Even though I don't think thermal issues would be a problem I'm obviously not funding this and not paying for replacement drivers so it is good to make the OP aware of all this.

One final point. I don't know your definition of "beating the snot out of" but the sim I showed is 3 db higher at tuning and almost 10 db higher at certain spots above tuning. I don't see the thermal issues as being a large factor like you do, so IMO I did beat the snot out of it. Give me a bit more room (larger enclosure size limitation) and I could beat the snot out of it, kick it around for awhile, and then dance on it. Remember, I limited my enclosure size to the same size as the OP's tapped horn design and still beat it by a large margin in 3 minutes flat. Maybe my modesty leaves a bit to be desired but this isn't rocket science.

Last edited by just a guy; 29th April 2013 at 09:46 PM.
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Old 29th April 2013, 10:08 PM   #14
tb46 is offline tb46  United States
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Hi Trackzilla,

Post #7: "...tb46: Hrmmmm...got a rough I can look at?"

Sure. :-)

You may want to define the outside dimensions of your boxes.

Regards,
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Old 29th April 2013, 10:12 PM   #15
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I checked to see if Josh at data-bass.com had tested this driver. Unfortunately he had not. The only 12 inch tc driver he had tested was the lmsr. I believe it's this one.

TC Sounds LMS-R 12" DVC Subwoofer 293-658

So as you can see the manufacturer's specs say it's rated for 1000 watts rms.

Data-bass.com did not actually state how many watts they tested this driver with on any page that I could find but they did measure Re at 4.15 ohms here:
Data-Bass
And measured spl with voltages up to 143 volts here (second graph - long term power compression):
Data-Bass

I used Hornresp to do the math for me since I'm very very bad at math.
143 volts at 4.15 ohms is very close to 5000 watts rms. As anyone might expect, there was significant power compression at this level.
But at 101 volts there was very minimal power compression. That's right around 2500 watts rms.

That's not so bad for a driver rated at 1000 watts rms. So if the little tc epic has anything in common with it's big lmsr brother you can see why I'm not too worried about power compression.

Last edited by just a guy; 29th April 2013 at 10:19 PM.
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Old 29th April 2013, 10:14 PM   #16
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Quote:
Originally Posted by tb46 View Post
You may want to define the outside dimensions of your boxes.

Regards,
He's got all the dimensions in the first attached pic in post #1.
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Old 29th April 2013, 10:23 PM   #17
tb46 is offline tb46  United States
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Hi just a guy,

Yes, he does, and then he changed things in Post #7. So, it would be nice to have some firm values to look at.

Regards,
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Last edited by tb46; 29th April 2013 at 10:26 PM.
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Old 29th April 2013, 10:28 PM   #18
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Quote:
Originally Posted by tb46 View Post
Hi just a guy,

Yes, he does, and then he changed things in Post #7. So, it would be nice to have some firm values to look at.

Regards,
Thanks, I was mostly focused on post #1 so I didn't notice any subsequent changes. I'll have to reread.

Anyway, if he's making changes, I'd suggest keeping the longest dimension at 96 inches so he can use regular 8 foot plywood.
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Old 29th April 2013, 10:42 PM   #19
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Originally Posted by just a guy View Post
... driver for driver it's almost 2.5x larger than the Labhorn rear chamber. To be painfully clear, the Lab has about 21 liters per driver and this design has 50 liters per driver.
I forgot to mention, this calculation assumes all 4 motors are in the rear chamber in my design. If he does do PPSL and has only 2 motors in the rear chamber, then those 2 motors would be sharing 200 liters (100 liters each), almost 5x more chamber size (per driver) than the Lab.

One other point that I forgot to mention is that I did not vet the chosen drivers for flh design, I just used the same drivers the OP used. Different drivers might yield even better results.
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Old 29th April 2013, 11:20 PM   #20
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Quote:
Originally Posted by just a guy View Post
And measured spl with voltages up to 143 volts here (second graph - long term power compression):
Data-Bass
I just noticed this link doesn't lead to the right spot. You have to click the "multi-series charts" tab on this page and then the "long term power compression" graph is the second graph on that page. I don't think there's any way I can link directly to the correct page.

It would be much easier to edit the original post than create a new post just for this, but that's life at diyaudio, I guess.
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