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Car Audio Subs In DYI Home Apps

post #1 of 29
3/17/11 at 7:33am
Thread Starter 
Was always curious about this.

With a sub like this one: http://mobile.jlaudio.com/products_s...p?series_id=40 while I'm certain it is a monster perfromer (if not a bit over priced) does it become nearly impossible to use them in a home app due to their very low (1.5 OHM) impedance.

And if so, what is it about the nature of car audio amplifiers that they can address such resistance while it's nearly impossible to find home amplifiers under thousands of dollars to pull of such a feat (2 ohms or less)?

Perhaps an ultra-high send sub like this is usually mated to an ultra high end car audio amp that's up to the task?

I ask because I COULD purchase this driver very reasonably from a long-time friend, but it appears very difficult to mate with a typical pro or home amp.

thanks!

James
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post #2 of 29
3/17/11 at 7:50am
You can run them in series to overcome impedance issues, however they aren't very good for home audio.

In a car, you can get away with limited displacement, but not as much in a room. Displacement is king here, and for the price of a driver like that, there are much better to be had for home use.

As for amplifiers, most car audio amplifiers capable of output at that range are class D amps. There aren't as many of those for home use, as most of the amps we use are AB or H. They're also pro audio amps, designed to power different types of speakers.
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post #3 of 29
3/17/11 at 8:06am
Thread Starter 
?

My understanding is/was that it's the identical driver used in their top of the line Fathom F113 and Gotham home subwoofers, which I thought put out prodigious amounts of bass in even the largest rooms: http://mobile.jlaudio.com/products_s....php?page_id=3

thanks for the info on the amps, that was my suspicion.

Again, I wouldn't normally consider a $1000 driver for a DYI app, but seeing he's willing to let it go brand-new for less than a 1/3 of that, that changes things a bit.


James
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post #4 of 29
3/17/11 at 10:50am
For the money you would pay for a Fathom or Gotham, you could EASILY get 4x the displacement for same if not less money.
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post #5 of 29
3/17/11 at 10:56am
car audio subs run lower impedances so the amps don't have to step up the voltage so much - after all the power supply is 12V (more like 13.5-13.8 ish) in a vehicle. Makes is easier to get more power.

There are DEFINITELY some very capable pro amps that can push loads of 1 ohm - the crown macro/micro tech series being a shining example. Those amps have a mode called "parallel-mono" that essentially wires the output devices in parallel (as opposed to series, which would be bridged mono) and thus allows you to push twice the current at the same voltage (also with about half the output impedance which is a big plus).

For my dad's HT, i had him purchase a micro-tech 2400, which ran about $600 used in mint condition and pushes 2000 watts RMS into 1 ohm if you want it to.
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post #6 of 29
3/17/11 at 11:55am
The gotham is $7k and has 12.7 Liters of displacement - which admittedly is quite a feat with the size of the drivers - 2 18" subs would give more displacement with a lot less money if you have the room for large boxes.

As far a whether the JL is worth it, depends on how much you can get it for.

Something like 2 Fi Q18's would give you 3-4 times the displacement as the JL for $600
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post #7 of 29
3/17/11 at 12:34pm
Quote:
Originally Posted by mastermaybe View Post

?

My understanding is/was that it's the identical driver used in their top of the line Fathom F113 and Gotham home subwoofers, which I thought put out prodigious amounts of bass in even the largest rooms: http://mobile.jlaudio.com/products_s....php?page_id=3

thanks for the info on the amps, that was my suspicion.

Again, I wouldn't normally consider a $1000 driver for a DYI app, but seeing he's willing to let it go brand-new for less than a 1/3 of that, that changes things a bit.


James

The Fathoms are great subs for commercial, though extremely overpriced. You're posting in the DIY section. They aren't worth much here. Different world Welcome to the party.

You can get 4 Fi Q 18s for $1000. They will crush one of those in output =]
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post #8 of 29
3/17/11 at 4:18pm
Thread Starter 
Quote:
Originally Posted by notnyt View Post


The Fathoms are great subs for commercial, though extremely overpriced. You're posting in the DIY section. They aren't worth much here. Different world Welcome to the party.

You can get 4 Fi Q 18s for $1000. They will crush one of those in output =]

I'm not sure where it got lost in this discussion, but I can get the driver ~$300.

Again, I'm not talking about buying a Gotham or Fathom. I'm not talking about spending $1000-$1200 on this driver. $300.

Thanks for the info on the pro amp capabilities. I was just told yday on these threads that NO pro amp exists that can push serious power (1000+ watts) into 2 ohms, never mind 1.

And if the Crown or other amps you speak of are $1000 or more than they're out as thats's simply too costly for a DYI like this. But it appears yours was $600 used, so that's great for such power, I suppose.



Thanks,
James
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post #9 of 29
3/17/11 at 4:19pm
Thread Starter 
Quote:
Originally Posted by notnyt View Post


The Fathoms are great subs for commercial, though extremely overpriced. You're posting in the DIY section. They aren't worth much here. Different world Welcome to the party.

You can get 4 Fi Q 18s for $1000. They will crush one of those in output =]

The inclusion of the Gotham and Fathom was to simply indicate that the driver in question is already used in state of the art home subwoofers. That's it.

James
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post #10 of 29
3/17/11 at 4:54pm
Quote:
Originally Posted by mastermaybe View Post

I'm not sure where it got lost in this discussion, but I can get the driver ~$300.

Again, I'm not talking about buying a Gotham or Fathom. I'm not talking about spending $1000-$1200 on this driver. $300.

Thanks for the info on the pro amp capabilities. I was just told yday on these threads that NO pro amp exists that can push serious power (1000+ watts) into 2 ohms, never mind 1.

And if the Crown or other amps you speak of are $1000 or more than they're out as thats's simply too costly for a DYI like this. But it appears yours was $600 used, so that's great for such power, I suppose.



Thanks,
James

For under $300 you can buy an 18 that will provide more output. They're good drivers, but even for $300 the value isn't there.

Now buying it and selling it to someone who doesn't know better for either car or home may be worth it =]
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post #11 of 29
3/17/11 at 5:26pm
Thread Starter 
Quote:
Originally Posted by notnyt View Post


For under $300 you can buy an 18 that will provide more output. They're good drivers, but even for $300 the value isn't there.

Now buying it and selling it to someone who doesn't know better for either car or home may be worth it =]

Wow. Looks like I need to get acquainted with some of these sub $300 drivers that will compete with this:

110dbs @23hz 2meters GP with exceptionally low distortion.

In room couldn't you expect ~120dbs then @23hz?


http://www.hometheaterhifi.com/subwo...w.html?start=2
http://home.jlaudio.com/pdfs/AbsoluteSound.pdf

Can you point out one of these budget 18's that surpass this performance for me? Thanks!

James
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post #12 of 29
3/17/11 at 8:21pm
alot of people here see car sub and think its automatically bad. that jl has a 32in xmax.

for 300 bucks. I'd pick one up for the house. at rated power for each, the fi q 18 someone menetioned here is a ~3db louder, ~6db if both have the same power level. But the jl audio goes flat for another few hz. And the fi audio sub requires a box 50% larger (~6cuft for the jl box, vs 9cuft for the fi)
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post #13 of 29
3/17/11 at 8:30pm
32 inch xmax huh? That's pretty impressive

6db sensitivity difference is nothing to sneeze at, the Fi Q will crush that sub. That means it takes four times as much power to get the same level out of the JL as it does the Fi Q. I'd even take a Mach 5 IXL 18.2.2 before that for in home use.

I ran 4x13av.2's, which are basically clones of that jl. They could not go loud and deep enough due to the lack of displacement. It's basic physics. a 13" driver is just going to leave you wanting more. You can get a pair of Dayton Titanic MK3s for $150, put them in a dual woofer enclosure and be set.

Also, there are MFW 15 drivers flooding the market right now for like $75 a piece. Four of those will definitely surpass the JL driver.

Don't think I'm hating on JL either. I run their subs in my cars.
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post #14 of 29
3/17/11 at 8:35pm
For $300 you aren't out much but your time. If it doesn't work out as well as you think you can easily get your money back on Ebay with a W7. You would still need/want a pro-amp to push whatever sub you chose for your DIY project, especially since you are looking at trying to accomplish 120DB @ 23hz.

Another option is there is a guy, EricH, that is selling the MFW-15 single voice coil sub. I think he's doing $77 a woofer plus shipping (figure about $25 per woofer for a good estimate to the continental U.S.). So 4 of those plus a Behringer EP4000 (2000WRMS) would put you at about $800 not including materials to build cabinets and would probably out do that one JL 13W7. Just an option though, if you are like me you'll like to say "Ya, that's just one sub."
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post #15 of 29
3/18/11 at 4:00am
Quote:
Originally Posted by notnyt View Post

32 inch xmax huh? That's pretty impressive

6db sensitivity difference is nothing to sneeze at, the Fi Q will crush that sub. That means it takes four times as much power to get the same level out of the JL as it does the Fi Q. I'd even take a Mach 5 IXL 18.2.2 before that for in home use.

I ran 4x13av.2's, which are basically clones of that jl. They could not go loud and deep enough due to the lack of displacement. It's basic physics. a 13" driver is just going to leave you wanting more. You can get a pair of Dayton Titanic MK3s for $150, put them in a dual woofer enclosure and be set.

Also, there are MFW 15 drivers flooding the market right now for like $75 a piece. Four of those will definitely surpass the JL driver.

Don't think I'm hating on JL either. I run their subs in my cars.

i've tried to model the mfw 15, maybe I did it wrong, but it was peaky.

As I said before, if you run both the fi and jl at their rated power, 1000w vs 1500w, the difference is 3db. BUT, the jl models flat for more then 6 hz, to below 20. and requires a box thats 33% smaller then the FI. So yes if you are going for abosulte loundness, go with something else.

But the JL sub will do well in a HT enviroment.
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post #16 of 29
3/18/11 at 6:30am
Thread Starter 
In the end it would prolly be difficult to convince me that the W7 is not a good deal at $300, I guess. The numbers and the build quality of the thing are universally acclaimed.

What I keep thinking about it is the output vs. the cab size. Jesus, they're pulling those figures out of a cube SMALLER than 18" HWD!!!

I can completely see a 18" driver in a larger box eclipsing the specs for obvious reasons, and thankfully I don't have "size" issues, lol, so that's still on the table.

If I could get near 120db output anywhere into the room I think I'd actually take a few more hz and improved linearity over 3-6dbs of output.

Thanks for the info guys. It's nice to know you can build quite a monster under 1k.

James
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post #17 of 29
3/18/11 at 9:12am
Quote:
Originally Posted by mastermaybe View Post

In the end it would prolly be difficult to convince me that the W7 is not a good deal at $300, I guess. The numbers and the build quality of the thing are universally acclaimed.

What I keep thinking about it is the output vs. the cab size. Jesus, they're pulling those figures out of a cube SMALLER than 18" HWD!!!

I can completely see a 18" driver in a larger box eclipsing the specs for obvious reasons, and thankfully I don't have "size" issues, lol, so that's still on the table.

If I could get near 120db output anywhere into the room I think I'd actually take a few more hz and improved linearity over 3-6dbs of output.

Thanks for the info guys. It's nice to know you can build quite a monster under 1k.

James

120db in room from a 13" driver in a sealed box is not likely.

Good luck though.
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post #18 of 29
3/18/11 at 10:55am
Quote:
Originally Posted by opfreak View Post

i've tried to model the mfw 15, maybe I did it wrong, but it was peaky.

As I said before, if you run both the fi and jl at their rated power, 1000w vs 1500w, the difference is 3db. BUT, the jl models flat for more then 6 hz, to below 20. and requires a box thats 33% smaller then the FI. So yes if you are going for abosulte loundness, go with something else.

But the JL sub will do well in a HT enviroment.

Most home subs when modeled will be peaky but in room dynamics, amplifier, and the subs resonance need to be taken into context as well. I doubt the MFW-15's wouldn't be poplar in in this forum if they weren't a quality driver since for a bit more you could pick up some decent Dayton drivers.
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post #19 of 29
3/22/11 at 7:27am
This will probably be received as rude but you can completely ignore the ignorant. What I mean is, everyone telling you it is a bad idea or it will not work simply has never done it.
I have.

It works great.
I've done it with both home audio and pro audio.
Comparing a pro audio paper speaker side by side with an aluminum cone car audio woofer, the only difference you will truly experience is sound texture due to the materials of the cones.
You're dealing with 96dB vs 110dB which is quite misleading.
This test result is generated with 1 watt @ 1 meter typically with a 1khz test tone. In the grand scheme of intentions, this information is worthless.



4x2x2 ft cabs with twin aluminum cone 15's. These are $25 750 wattt RMS car woofers that with 400 watts RMS through one cabinet at moderate volume was pushing 160dB. No crossover, just a safety fuse and the EQ on my PA mixer to deal with the curve of the woofers. Remember, 96dB out the front also means 96dB out the back(take a little) so your cabinet can be designed to bounce some of that back out the front.

Why is it guys insist it "won't work" or is a bad idea?
Arrogance. It's all about confining oneself to the stipulations of a field so they can be acknowledged as knowledgeable. Really they're just regurgitating something they read or were told. This being the foundation of all ignorance IMP.
This pair of cabinets with a subwoofer will cover sound for easily a few thousand people. Rule of thumb is 1 watt RMS per audience member but with today's equipment 1 watt RMS can truly cover 3-4 people.

Using a car sub in your house will be just fine if the impedance matches and often with today's equipment, unless you're at ear shattering levels the amps can handle a lower load than rated for. Countless people running systems under such conditions for years will vouch, myself included.
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post #20 of 29
3/22/11 at 7:37am
"4x2x2 ft cabs with twin aluminum cone 15's. These are $25 750 wattt RMS car woofers that with 400 watts RMS through one cabinet at moderate volume was pushing 160dB."

Riiiiight!!

Better call up Danley Sound Labs, you can crush the "Rock Monster" TH-812.....

http://www.danleysoundlabs.com/tapped_horn.asp?MODEL=TH%20812
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post #21 of 29
3/22/11 at 7:53am
Quote:
Originally Posted by JonnySwitchblade View Post

This will probably be received as rude but you can completely ignore the ignorant. What I mean is, everyone telling you it is a bad idea or it will not work simply has never done it.
I have.

It works great.
I've done it with both home audio and pro audio.
Comparing a pro audio paper speaker side by side with an aluminum cone car audio woofer, the only difference you will truly experience is sound texture due to the materials of the cones.
You're dealing with 96dB vs 110dB which is quite misleading.
This test result is generated with 1 watt @ 1 meter typically with a 1khz test tone. In the grand scheme of intentions, this information is worthless.



4x2x2 ft cabs with twin aluminum cone 15's. These are $25 750 wattt RMS car woofers that with 400 watts RMS through one cabinet at moderate volume was pushing 160dB. No crossover, just a safety fuse and the EQ on my PA mixer to deal with the curve of the woofers. Remember, 96dB out the front also means 96dB out the back(take a little) so your cabinet can be designed to bounce some of that back out the front.

Why is it guys insist it "won't work" or is a bad idea?
Arrogance. It's all about confining oneself to the stipulations of a field so they can be acknowledged as knowledgeable. Really they're just regurgitating something they read or were told. This being the foundation of all ignorance IMP.
This pair of cabinets with a subwoofer will cover sound for easily a few thousand people. Rule of thumb is 1 watt RMS per audience member but with today's equipment 1 watt RMS can truly cover 3-4 people.

Using a car sub in your house will be just fine if the impedance matches and often with today's equipment, unless you're at ear shattering levels the amps can handle a lower load than rated for. Countless people running systems under such conditions for years will vouch, myself included.

Nice first post, looks like a troll account. 160db in room eh? I don't think so buddy. The original post was asking about a 13" JL driver, which doesn't have the displacement to perform adequately in a room, as opposed to a car. Where are you coming up with this crap?
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post #22 of 29
3/22/11 at 8:14am
134db sensitivity? Wow, where do I get a pair?
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post #23 of 29
3/22/11 at 9:30am
Quote:
Originally Posted by JonnySwitchblade View Post

This will probably be received as rude but you can completely ignore the ignorant. What I mean is, everyone telling you it is a bad idea or it will not work simply has never done it.

I don't think anyone here is saying that it is a bad idea or will not work - The JL is a good driver and will definitely work for a home subwoofer - What people are saying is that there are better options for a home sub even for $300. An 18" driver with 28-30mm xmax simply has much more displacement than a 13" driver with 32mm xmax.

If the JL driver fits the original posters needs and cannot deal with a larger box that an 18" driver would require then the JL might make an excellent driver. But it is not arrogant or ignorant to attempt to answer the OP's question with real facts not some BS about 160db bass (I can only assume you mean bass since that is what we are talking about here) from 2 15" drivers. That is simply not in the realm of possibility. Your measurement gear must be broken.
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post #24 of 29
3/22/11 at 9:50am
I've used car woofers, I've used pro woofers, I've used home woofers....

Some sucked, some rocked, some died trying.

Which is best? The right woofer in the right cabinet.

It all comes down to putting whatever driver you choose to use into a cabinet that optimizes the system's performance to achieve the frequency reproduction goal you're trying to reach without compromising the rest of the design criteria too much.

Sorry that I can't be more clear. A lousy driver is a lousy driver. A great driver is a great driver. I've had more of the former than the latter. Some were designed for cars, some for PA systems, some for home theater. All have their good points, but all have some compromises, certainly all have their limitations. A great cabinet can help a lousy driver a bit, but cabinets can not work miracles. More importantly - a lousy cabinet will make the best driver ever sound terrible.

Think of the cabinet and the driver as a system.

Good driver + good cabinet = good results

By the way - set realistic goals. 120 dB from a single 12 at 20 Hz is not likely in a home theater setting.

160 dB with a pair of SWEET-LOOKING white-van or flea-market drivers? Ummmm, yeah.
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post #25 of 29
3/23/11 at 10:43am
400 watts RMS running a full frequency cabinet won't produce 160dB?
News to me and my meter!

The logic of those saying nay is frequency dependent.
160db at 20Hz?
Where in the world did I say this...did I say this?
I sure don't seem to remember nor can I find it in my post.
I also know my cabinet couldn't produce 160dB at 120Hz let alone 20.

I simply said 1 cabinet powered by my PA with the EQ contoured to tame and excite the right frequencies pushed 160dB on my SPL meter. I'm simply saying to the OP that you only know by doing, not by letting others tell you. I share the same philosophy as lilmike.

I will also repeat, in the grand scheme of intention a 110dB rating of a loudspeaker is misleading and altogether useless. Well, unless the purpose is strictly to generate a 1Khz test tone though for what purpose I know none. Show me a company that does a broad sweep of frequencies and specs us how many dB for a logical group of frequencies then feel free to mock me because the standard of classifying speaker sensitivity will no longer be in your favor.
The argumentative offense here is claiming 110dB sensitivity rating is relevant when you intend to filter 20Hz through the speaker which could not be more false. The reality here being is a speakers manufacturer given spec of wattage rating isn't even relevant for said frequency.
It fractions.

So ultimately the only true relevance is can you afford it, do the given specs make it a potential success for your project and then most of all the end results.
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post #26 of 29
3/23/11 at 10:58am
"400 watts RMS running a full frequency cabinet won't produce 160dB?
News to me and my meter!
"

Where can I buy such a meter? Hitting 125 db@ 1m is a hard enough job for most main speakers.... Even a Klipschorn or Lascala have troubles doing that.
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post #27 of 29
3/23/11 at 11:10am
Quote:
Originally Posted by mastermaybe View Post

I ask because I COULD purchase this driver very reasonably from a long-time friend, but it appears very difficult to mate with a typical pro or home amp.

thanks!

James

What are your goals with this design? I ask because, like others have mentioned, although the JL W7 will be an awesome SQ driver it won't be an SPL monster. I note that your tagline is "VALUE is critical!!!" I just though it should be pointed out that although a good deal for the W7 from a value perspective there are better options if space will allow. Regarding the thoughts that you may be able to get 120dB in-room at 20hz I think that's a bit of a stretch. Here's the max SPL measurements taken by Ilkka of the JL Fathom F113 sub:


That's not in a room of course but it's also 1m (or is it 2m? couldn't find it in the testing methodology thread?). At 20hz it's topping out at 100dB, in-room you'll probably get something similar, maybe a couple dB more but not 20

That said you really don't have anything to lose, you could buy it for $300 and sell it for a bit more if you don't like it (I have seen them on craigslist for about that price though so I'm not sure it's a "killer" deal) so it may be a good way to test the DIY waters
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post #28 of 29
3/23/11 at 11:21am
Quote:
Originally Posted by michael hurd View Post

"400 watts RMS running a full frequency cabinet won't produce 160dB?
News to me and my meter!
"

Where can I buy such a meter? Hitting 125 db@ 1m is a hard enough job for most main speakers.... Even a Klipschorn or Lascala have troubles doing that.

135dB 1W/1M FTW
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post #29 of 29
3/23/11 at 11:24am
Thread Starter 
Well, I can put the breaks on right here, gentlemen.

I decided to let ED make their money doing what they do:

They built me an A7-450 gloss black passive sub for what I believe is an exceptionally fair price for a umpteen-braced, 300lb, ported cabinet and an extremely capable 18" driver shipped to my front door.


When it came right down to it, my time (first kid ion the way) energy, and lack of expertise simply pushed me in the other direction for now.

And yes, I certainly DO recognize the fact that there's perhaps MORE value in other drivers...I just also likely place a higher premium than most on my time. Just me, that's all.

And that's not to discount those who really enjoy cabinet construction and the like, because if they truly do, then it's a TRIPLE win for them. Money. Fun. Performance.

Down the road some day, for me.

Thanks again and much respect,

James
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