High-end SQ/IB setup questions.
- Thread starter Buffalohed
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Buffalohed
w00tah
10+ year member
Captain Keffa
From what I've gathered on here and other boards, the Image Dynamics IDQ15 is an excellent IB sub. As for the Aura, I can only dream of that sub, pricey as it is. It looks good on paper though.
Now, the amps you chose, I'd personally take the DLS. The JL / amps are current hogs, at least from what I've seen personally. The only good thing is that any load works on it, so long as it's between 1.5-4 ohm. I'd take the DLS mainly for the headroom it'll give you.
Can't really help much about the THD, because I've never seen anything posted resembling your question before, thus I've never seen an answer.
The last thing I'll say is make sure your fronts are more than capable of keeping up with whatever you buy.
Good luck, and I hope someone can help out more than I could.
Morgan
Now, the amps you chose, I'd personally take the DLS. The JL / amps are current hogs, at least from what I've seen personally. The only good thing is that any load works on it, so long as it's between 1.5-4 ohm. I'd take the DLS mainly for the headroom it'll give you.
Can't really help much about the THD, because I've never seen anything posted resembling your question before, thus I've never seen an answer.
The last thing I'll say is make sure your fronts are more than capable of keeping up with whatever you buy.
Good luck, and I hope someone can help out more than I could.
Morgan
I can't help you, but since you have Spinoza in your sig I know you'll make the right choice. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif
helotaxi
5,000+ posts
Kilroy was Here
I would place about zero stock in spec THD numbers. Outside of independant testing, thee is no way to confirm their veracity. I have no doubt that the JL and DLS amps will blow their specs away, but my real point is don't get too wrapped up in manufacturers specs. There is no standard and as such any numbers can't be compared between companies.
As far as THD being cumulative, that is true, however, 5 components in a signal chain is a lot, a whole lot actually. HU, processor, amp is about all I would expect. Next thing is that 1% is considered the ragged edge of audibility for a trained ear. Any components worth having will keep the level well below that threshold. Signal to noise likewise. Throw in that most speakers are going to introduce as much as 10% distortion and you can see that solid electronics are important but not as important as the speakers themselves when it come to reproducing the sound accurately since the speakers will make most of the distortion.
At the power level that you're looking at, don't be concerned with people who say that the JL amps are current hogs. Compared to the most efficient Class D amps out there, they may be a little greedy, but I'd much rather deal with the current consumption of a 500/1 than one of my old Class A/B amps putting out the same power. The rated draw of the Class A/B is higher than the fuse rating of the JL.
Lastly, when it comes to power handling in an IB setup, thermal power handling (what a spec indicates) is pretty much never the limiting factor. Mechanical power handling is what will limit the power you can safely send to the driver. In a true IB setup the woofer is pretty much on its own when it comes to controlling its cone movement. Unlike with a conventional ported or sealed enclosure, there is no air spring helping to dampen cone movement (it also won't color the sound which is why IB setups are so well liked for SQ installs). As such it takes a lot less power to get the sub to move to its suspension limit. If the sub has a lot of suspension overhang compared to the distance that the motor can actually move it (a lot of the high output subs fall into this category) you really don't have to worry, but that isn't always the case. If the motor is capable of driving the sub to its suspension limit it will happen with the least amount of power in an IB setup.
I don't have experience with the drivers that you've mentioned. The sub is really only going to be responsible for less than 2 octaves of the audible spectrum, so stressing over it isn't that necessary. You can obviously spend a fortune on a substage, but it isn't usually necessary in an SQ setup. The Image Dynamics IDQ as mentioned is a great IB driver and very budget friendly as well, which frees up more money for what really matters, the front stage components...
If you have any other questions, don't hesitate to ask.
As far as THD being cumulative, that is true, however, 5 components in a signal chain is a lot, a whole lot actually. HU, processor, amp is about all I would expect. Next thing is that 1% is considered the ragged edge of audibility for a trained ear. Any components worth having will keep the level well below that threshold. Signal to noise likewise. Throw in that most speakers are going to introduce as much as 10% distortion and you can see that solid electronics are important but not as important as the speakers themselves when it come to reproducing the sound accurately since the speakers will make most of the distortion.
At the power level that you're looking at, don't be concerned with people who say that the JL amps are current hogs. Compared to the most efficient Class D amps out there, they may be a little greedy, but I'd much rather deal with the current consumption of a 500/1 than one of my old Class A/B amps putting out the same power. The rated draw of the Class A/B is higher than the fuse rating of the JL.
Lastly, when it comes to power handling in an IB setup, thermal power handling (what a spec indicates) is pretty much never the limiting factor. Mechanical power handling is what will limit the power you can safely send to the driver. In a true IB setup the woofer is pretty much on its own when it comes to controlling its cone movement. Unlike with a conventional ported or sealed enclosure, there is no air spring helping to dampen cone movement (it also won't color the sound which is why IB setups are so well liked for SQ installs). As such it takes a lot less power to get the sub to move to its suspension limit. If the sub has a lot of suspension overhang compared to the distance that the motor can actually move it (a lot of the high output subs fall into this category) you really don't have to worry, but that isn't always the case. If the motor is capable of driving the sub to its suspension limit it will happen with the least amount of power in an IB setup.
I don't have experience with the drivers that you've mentioned. The sub is really only going to be responsible for less than 2 octaves of the audible spectrum, so stressing over it isn't that necessary. You can obviously spend a fortune on a substage, but it isn't usually necessary in an SQ setup. The Image Dynamics IDQ as mentioned is a great IB driver and very budget friendly as well, which frees up more money for what really matters, the front stage components...
If you have any other questions, don't hesitate to ask.
OP
Buffalohed
10+ year member
Music Snob Extraordinare
- Thread Starter
- #5
Thanks for the responses fellas.
My question about THD was answered perfectly, thanks. I realize you can't take too much stock in published ratings, but it seems like a great thing to keep in mind when purchasing components for a system - keeping the overall THD low seems like a worthwhile goal for a SQ setup.
What you (helotaxi) explained about power handling makes pretty good sense to me right now. The only thing is I have no idea how to determine any of those things about a sub. Are there any specific stats I should look for to indicate suspension overhang and motor efficiency and hence what kind of power would be required in an IB setup, or how easily xmax will be reached?
The reason I chose Aura as my first choice was largely because of its top place in the 12" challenge, and also because I am worried about the output of only a single 15" IDmax or Q. I would be really interested if anyone can guesstimate if the Aura would work well IB. As far as the frontstage is concerned, that will be upgraded in due time as well, probably some time this summer, where I will be looking at getting Rainbow Platinums or something similar.
Also would be thrilled if anyone has input on the other subs mentioned. And I'd like to re-word the question about IB... In order to fit a 15" IB my baffle will most likely be multiple pieces. Meaning it won't be a flat board, but will probably end up having a diagonal piece along with two vertical pieces. As long as the baffle is sturdy and the compartment sealed, is this something I should be concerned about?
My question about THD was answered perfectly, thanks. I realize you can't take too much stock in published ratings, but it seems like a great thing to keep in mind when purchasing components for a system - keeping the overall THD low seems like a worthwhile goal for a SQ setup.
What you (helotaxi) explained about power handling makes pretty good sense to me right now. The only thing is I have no idea how to determine any of those things about a sub. Are there any specific stats I should look for to indicate suspension overhang and motor efficiency and hence what kind of power would be required in an IB setup, or how easily xmax will be reached?
The reason I chose Aura as my first choice was largely because of its top place in the 12" challenge, and also because I am worried about the output of only a single 15" IDmax or Q. I would be really interested if anyone can guesstimate if the Aura would work well IB. As far as the frontstage is concerned, that will be upgraded in due time as well, probably some time this summer, where I will be looking at getting Rainbow Platinums or something similar.
Also would be thrilled if anyone has input on the other subs mentioned. And I'd like to re-word the question about IB... In order to fit a 15" IB my baffle will most likely be multiple pieces. Meaning it won't be a flat board, but will probably end up having a diagonal piece along with two vertical pieces. As long as the baffle is sturdy and the compartment sealed, is this something I should be concerned about?
helotaxi
5,000+ posts
Kilroy was Here
Your major concern when setting up an IB install is going to be sealing the trunk off from the cabin. It's a lot of work and can be a pain in the butt. Beyond that, you do what you have to do to mount the subs you want to use. It is plausible to install a pair of 18s IB with a seatback height of only 14" if you don't mind getting creative with the install. There's a link on here somewhere to an IB install that the Image Dynamics guys were doing with 4 driver in a fiberglass layout at all kind of odd angle to get them to fit.
If you want to get an idea of power handling and so forth on the the different subs, download WinISD (http://www.linearteam.org) and set up the particular sub you are wondering about in a really large sealed enclosure and start playing with the input power and looking at the excursion plot. The power required to get it to Xmax is about the amount of power you will need to get the most out of the sub. A little more to account for power compression and front side loading from the cabin of the vehicle and a little headroom isn't a bad thing.
Some subs will have an Xsus spec which is the suspension limit. Some also have Xmag which how far the motor can move the cone. The hope is that the first is larger than the second. In that case the sub will pretty much never bottom out in a sealed or free air environment (ported is a different story). If you don't have that info, you can always get an amp a little bigger than you think you need and use a combination of a subsonic filter and a conservative gain setting to keep it from bottoming. You can use a subsonic filter to keep the excursion form getting out of control at really low freqs (you'll still get usuable output down low) while allowing for more excursion, and thus more output, at higher freqs. In this respect, as long as you have a subsonic filter that you can adjust, you can come pretty much put rated power to the sub. Excursion, not heat, is your concern with music 95% of the time anyway.
If you want to get an idea of power handling and so forth on the the different subs, download WinISD (http://www.linearteam.org) and set up the particular sub you are wondering about in a really large sealed enclosure and start playing with the input power and looking at the excursion plot. The power required to get it to Xmax is about the amount of power you will need to get the most out of the sub. A little more to account for power compression and front side loading from the cabin of the vehicle and a little headroom isn't a bad thing.
Some subs will have an Xsus spec which is the suspension limit. Some also have Xmag which how far the motor can move the cone. The hope is that the first is larger than the second. In that case the sub will pretty much never bottom out in a sealed or free air environment (ported is a different story). If you don't have that info, you can always get an amp a little bigger than you think you need and use a combination of a subsonic filter and a conservative gain setting to keep it from bottoming. You can use a subsonic filter to keep the excursion form getting out of control at really low freqs (you'll still get usuable output down low) while allowing for more excursion, and thus more output, at higher freqs. In this respect, as long as you have a subsonic filter that you can adjust, you can come pretty much put rated power to the sub. Excursion, not heat, is your concern with music 95% of the time anyway.
req
5,000+ posts
am a mod.
i have ran a pair of IDQ15's IB for a while. i am going to reinstall them asap in my new vehicle that way as well. and ill be using dls ultimate A5's for the front and rear stage, and most likely in the near future upgrading or adding another ho alternator.
for me, i like to have the cone area to make up for the suspension limited mechanical handling. i dont like the idea of running my sub into xmech if i can help it, so i doubled up.
like hex said, the front stage is what really matters in an install of the proportions you are interested in.
sadly i have no expierence with the aformentioned drives you have mentioned, but again the look good on paper. i personally would look at drivers with a sub .35 qts, but thats not a huge factor when its so close. mainly you want to make sure the xmech is not motor limited (like a backplate that is too close to the full excursion of the coil) - you will hear that easy if such is the case. the IDQ has a huge bumped backplate to alliviate this problem.
heres a link to my install of my system before i went to the navy. i did not have a chance to finish it to my desire because a, i had no job. and b, i didnt have any more time. so i dealt with it.
http://www.caraudio.com/forum/showthread.php?t=139980
i read it all, and i cant remember your questions lol. ask the ones you are most concerned with again lol
//edit
some fun links for you
http://www.imagedynamicsusa.com/gallery/main.php?g2_view=core.ShowItem&g2_itemId=2963
http://www.imagedynamicsusa.com/gallery/main.php?g2_view=core.ShowItem&g2_itemId=3329
for me, i like to have the cone area to make up for the suspension limited mechanical handling. i dont like the idea of running my sub into xmech if i can help it, so i doubled up.
like hex said, the front stage is what really matters in an install of the proportions you are interested in.
sadly i have no expierence with the aformentioned drives you have mentioned, but again the look good on paper. i personally would look at drivers with a sub .35 qts, but thats not a huge factor when its so close. mainly you want to make sure the xmech is not motor limited (like a backplate that is too close to the full excursion of the coil) - you will hear that easy if such is the case. the IDQ has a huge bumped backplate to alliviate this problem.
heres a link to my install of my system before i went to the navy. i did not have a chance to finish it to my desire because a, i had no job. and b, i didnt have any more time. so i dealt with it.
http://www.caraudio.com/forum/showthread.php?t=139980
i read it all, and i cant remember your questions lol. ask the ones you are most concerned with again lol
//edit
some fun links for you
http://www.imagedynamicsusa.com/gallery/main.php?g2_view=core.ShowItem&g2_itemId=2963
http://www.imagedynamicsusa.com/gallery/main.php?g2_view=core.ShowItem&g2_itemId=3329
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