Can someone please run my parameters and find the perfect box for my sub?

  • Thread starter cameron paterson
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cameron paterson

Audioholic Chief
So I just read that a ported sub should have a Qts of .35 or less. and a sealed sub should have a Qts of .45 or higher. And anything in between can go ported or sealed. The Qts of my TC sounds 18" is .325... so why is a ported enclosure bad?
 
TLS Guy

TLS Guy

Seriously, I have no life.
So I just read that a ported sub should have a Qts of .35 or less. and a sealed sub should have a Qts of .45 or higher. And anything in between can go ported or sealed. The Qts of my TC sounds 18" is .325... so why is a ported enclosure bad?
That is just a rough rule of thumb. The problem is that ported the port ends up just far too long and you have a massive port resonance. That driver might work with an ABR, but we would probably have trouble sourcing a suitable unit. That driver does not model well ported, but it does sealed.
 
ski2xblack

ski2xblack

Audioholic Field Marshall
So I visited Cameron's place to hear this beast of a sub.

I promised not to haze him regarding some of the music selections, although it's SOOO tempting. Lets just say some of it was highly processed pop, Specter style 'wall of sound' production quality, bombastic as all hell. And Cameron likes it really loud.

I think highfigh's take is about right. It's more muddy than Cameron probably realizes, and comparing to a puny JL being flogged to death to keep up doesn't really prove much of anything other than his room is too large for a puny JL sub. He's got some attachment to the enclosure he has, new toy factor and all that, and it really is loud as fucke with no signs of distress, which, muddy or not, is kind of impressive, at least to one who has yet to experience really tight, defined bass. His current room is a limiting factor on top of that, and wasn't handling the extreme spls without adding it's own coloration, so I suggested Toole's book and the articles on acoustics and system setup here. As expressed in the thread here he's a bit resistant to build a more optimal box. But that's what I suggested, and a pro amp with the requisite eq, so basically everything that you folks have already mentioned in this thread.

Cameron, if you don't want to deal with the dust and hassle, you could contract someone to do it for you (highly recommended...let them clean up the sawdust). I can even recommend somebody local to you in Longmont for that task. That driver is a good one, and you really should put it to best use.
 
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cameron paterson

Audioholic Chief
I don't want to go sealed because I need a new box plus something like an Inuke to EQ the poop out of it to hit the low bass notes. I got winisd to work on my girls computer so I'm going to put in the parameters and set it up with my boxes size and port size and tuning. I will then try to copy and paste the results from winisd so you can see the performance on 'paper'.
 
everettT

everettT

Audioholic Spartan
I don't want to go sealed because I need a new box plus something like an Inuke to EQ the poop out of it to hit the low bass notes. I got winisd to work on my girls computer so I'm going to put in the parameters and set it up with my boxes size and port size and tuning. I will then try to copy and paste the results from winisd so you can see the performance on 'paper'.
Sealed is what you want, you dont and cant eq a ported sub below its tuning with out risk of damage.
 
Sheep

Sheep

Audioholic Warlord
I don't want to go sealed because I need a new box plus something like an Inuke to EQ the poop out of it to hit the low bass notes. I got winisd to work on my girls computer so I'm going to put in the parameters and set it up with my boxes size and port size and tuning. I will then try to copy and paste the results from winisd so you can see the performance on 'paper'.
The second plot is a passive radiator setup. Minimal EQ needed besides room correction, but a 200 liter box.

SheepStar
 
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cameron paterson

Audioholic Chief
I never eq'd this ported sub with the eq on the Dayton amp. the eq goes down to 18hz. its tuned at 20hz. should I eq at 18hz and do it at like minus 2 or 3db? It is loud with a 20hz test tone right now with no eq'ing. I definitely do like it loud and am a basshead but I don't think my sub is that loose sounding ive heard tons of sealed subs in cars and in home theater rooms and this is not loose. ALso, TLSguy.... the port isn't that long tuned at 20hz its only a 39" long port in a 7.3ft3 enclosure after all displacements.
 
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everettT

everettT

Audioholic Spartan
Every project with your driver that i have seen has been sealed, very stable high output amp, and eq. Are you currently apply a high pass filter? If so what slope did you use?
 
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cameron paterson

Audioholic Chief
80hz low pass on the Dayton plate amp. my pioneer avr has the speakers set at 80hz high pass and I think it sets my sub at 80hz low pass as well. oh I think you mean a subsonic filter. don't have one. can I use my amps eq to set it at 18hz and drop the db's down a couple to keep the lower bass from coming thru? I tried a 20hz subsonic filter that you plug right into the amp and it cut way too high and was dropping the db's at 25hz even, not just 20hz. I didn't like the way it sounded. my amp also has a light that turns red when clipping so I never send the amp into clipping.
 
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everettT

everettT

Audioholic Spartan
The HPF protects your driver from decoupling and would be applied near the box tuning. You can do this even without driving the amp to clipping. A sealed sub, in theory, doesnt need a HPF. This allows for heavier eq below the F3.
 
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TLS Guy

TLS Guy

Seriously, I have no life.
I never eq'd this ported sub with the eq on the Dayton amp. the eq goes down to 18hz. its tuned at 20hz. should I eq at 18hz and do it at like minus 2 or 3db? It is loud with a 20hz test tone right now with no eq'ing. I definitely do like it loud and am a basshead but I don't think my sub is that loose sounding ive heard tons of sealed subs in cars and in home theater rooms and this is not loose. ALso, TLSguy.... the port isn't that long tuned at 20hz its only a 39" long port in a 7.3ft3 enclosure after all displacements.
39" is far too too long. the port is an open pipe and 39" is 1 meter and do that port will have a strong resonance and output at 172 Hz and a pretty strong second harmonic resonance at 344 Hz, which will really muddy the sound.

As I suspected, if you want a tuned enclosure this has to be a passive bass radiator design, like the one Sheep posted.

Also when designing an enclosure you do not pull a tuning frequency out of the air. The T/S parameters determine the optimal tuning frequency fb.
 
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cameron paterson

Audioholic Chief
I modeled 2 boxes on winisd. One at 7.3ft3 tuned at 20Hz and one at 4ft3 tuned at 20Hz. Both with 1000 watts total power. At 20Hz, the bigger box reads 116db and the smaller box reads 108db. The bigger box, at 15Hz, reads 111db and the smaller box reads 105db. At 30Hz and up, they are almost identical. 30Hz with small box was 116db and the bigger box was 118. Sorry I couldn't figure out how to upload the graphs here. Does this help with anything? The winisd said it should be ported and said 3.8ft3 tuned at 20hz.
 
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cameron paterson

Audioholic Chief
At 172Hz I have test tone cds and at 172Hz there is no sound coming from the sub at all its all coming from the front towers. Are you saying I need a bigger box than 7.3ft3 to make the port shorter?
 
lovinthehd

lovinthehd

Audioholic Jedi
The LPF protects your driver from decoupling and would be applied near the box tuning. You can do this even without driving the amp to clipping. A sealed sub, in theory, doesnt need a LPF. This allows for heavier eq below the F3.
You mean high pass filter-HPF I think.
 
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cameron paterson

Audioholic Chief
The sub is setup with a low pass filter of 80hz on the Dayton amp and on the pioneer AVR. The Kef's are also set at a 80hz high pass.
 
lovinthehd

lovinthehd

Audioholic Jedi
The sub is setup with a low pass filter of 80hz on the Dayton amp and on the pioneer AVR. The Kef's are also set at a 80hz high pass.
Why are you cascading filters? Or maybe I misunderstand your settings. You're using the low pass on the Dayton amp of 80hz? Then you compound it with using a crossover of 80hz in the Pioneer avr? Or by low pass on the Pioneer avr are you speaking of a setting for LPF of LFE? You somehow can set just a high pass for the speakers? Or is it just the crossover setting?
 
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cameron paterson

Audioholic Chief
Just the crossover setting is for both. Does anyone have anything to say about the kappa perfect box having a 55" long port?
 
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