# JL HD 750 falling short for two 10W7's



## NateZ28 (Oct 2, 2013)

I recently purchased a JL HD 750 and two JL 10W7's for my Genesis Coupe. I had an audio shop build a custom sealed box to JL spec, since I care more about sound quality than loudness. Unfortunately the box they built only has a partial divider, so the subs do share the airspace between the two chambers. My concern from the get-go was that the HD 750 would not be enough to power the two W7's, but the shop assured me it would be plenty loud in my small car.

After a few days I started turning the bass remote knob all the way up. It was decently loud, but was not quite what I expected from two W7's. Then I noticed the subs would sometimes cut out at full volume. So I brought it in to shop and they turned down the voltage output from the RCA adapter. I'm using the stock head unit so the adapter is taking the sound from the head unit and converting it to RCA. A Pioneer 80PRS is in my near future.

So I want these subs to be louder. I'm starting to think I may need more power. What do you guys recommend? An HD 1200, an additional HD750 so each sub has it's own amp, or a different brand of amp entirely? If I added another amp some modifications would have to be made to the box since they are sharing airspace right now. I don't need it to be deafening but I would like to actually hear and feel all of the bass in my music.


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## minbari (Mar 3, 2011)

the divider really has no being how the subs will sound, there are reasons for having or not having one, but SPL isnt one of them.

~350 for a W7 is certainly not going to push those to the limit, but I cant imagine why they wouldnt get loud on it. What size box did they use? if they are in 0.75cuft each I could see why.


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## .69077 (Aug 24, 2013)

Id say another HD750, plus there is one for sale in the classifieds for $300 shipped. Jump on that!

http://diymobileaudio.com/forum/showthread.php?t=154781 [/


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## NateZ28 (Oct 2, 2013)

minbari said:


> the divider really has no being how the subs will sound, there are reasons for having or not having one, but SPL isnt one of them.
> 
> ~350 for a W7 is certainly not going to push those to the limit, but I cant imagine why they wouldnt get loud on it. What size box did they use? if they are in 0.75cuft each I could see why.


The reason I mentioned the partial divider is because I know you need a full divider when using two amps. I understand that sound quality is not effected as long as there is enough air space.
According to the shop they built the box to JL's recommended specifications which is 2.5 cubic inches of air space for the two 10W7's.


m249saw said:


> Id say another HD750, plus there is one for sale in the classifieds for $300 shipped. Jump on that!


I would have to ask the shop to modify the box. Which may also slightly reduce the total air space. They would need to extend the existing divider so that it extends all the way to the back of the box. I might also have to upgrade my power wire. Right now everything is 4 AWG.


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## minbari (Mar 3, 2011)

NateZ28 said:


> The reason I mentioned the partial divider is because I know you need a full divider when using two amps. I understand that sound quality is not effected as long as there is enough air space.
> According to the shop they built the box to JL's recommended specifications which is 2.5 cubic inches of air space for the two 10W7's.


No you dont. as long as the subs are in phase, that is what matters. if one sub gets 760 watts and the other gets 740 watts it isnt going to make a hill of beans difference in the sound or performance. they will acoustically couple just like it was one amplifier.

Are these DVC? you want to null out the differences, run 1 coil from each sub to each amplifier. problem solved.

that should be enough airspace. I know the W7 will take a ton of power, maybe more power will solve it. it certainly cant hurt


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## NateZ28 (Oct 2, 2013)

minbari said:


> No you dont. as long as the subs are in phase, that is what matters. if one sub gets 760 watts and the other gets 740 watts it isnt going to make a hill of beans difference in the sound or performance. they will acoustically couple just like it was one amplifier.
> 
> Are these DVC? you want to null out the differences, run 1 coil from each sub to each amplifier. problem solved.
> 
> that should be enough airspace. I know the W7 will take a ton of power, maybe more power will solve it. it certainly cant hurt


Hmmm I had always been told that if two subs are running on separate amps they need separate enclosures. Otherwise you risk blowing a sub if one of the subs/amps stops playing, because one sub would have double the needed air space.
Would I need to upgrade my power wire? Right now everything is 4 AWG running off the stock alternator and battery.


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## minbari (Mar 3, 2011)

NateZ28 said:


> Hmmm I had always been told that if two subs are running on separate amps they need separate enclosures. Otherwise you risk blowing a sub if one of the subs/amps stops playing, because one sub would have double the needed air space.
> Would I need to upgrade my power wire? Right now everything is 4 AWG running off the stock alternator and battery.


that is a risk if they are on the same amp too. if one sub blows, the undamaged sub will not only see 2x the airspace but the dead sub will become a passive radiator.(tuned to god knows what freq)

unless you just say "screw it" and keep banging away on the good sub you are going to hear it instantly.

If you want the extra measure of safety the a full divider provides, by all means do it! but how it is amplified has nothing to do with it.

you might have to make a second run of 4ga. a single 4ga will support 120 amps of current. if you exceed that with more amplifiers, then yes, you will need more wire


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## NateZ28 (Oct 2, 2013)

minbari said:


> that is a risk if they are on the same amp too. if one sub blows, the undamaged sub will not only see 2x the airspace but the dead sub will become a passive radiator.(tuned to god knows what freq)
> 
> unless you just say "screw it" and keep banging away on the good sub you are going to hear it instantly.
> 
> ...


Hmm I'm trying to figure out the most cost effective way of doing this. I will eventually add another amp for the Focal KRX2's I plan to buy. That will be down the road. Right now I'm using the factory Infinity system which has it's own factory amplifier.


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## t3sn4f2 (Jan 3, 2007)

double post


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## t3sn4f2 (Jan 3, 2007)

What car? Where is the box located and in which direction is it facing? If the box is in a trunk, are there rear speakers that you can remove? Can you open up a ski pass/rear seat arm rest and cover it with a grill clothed screen?


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## NateZ28 (Oct 2, 2013)

t3sn4f2 said:


> What car? Where is the box located and in which direction is it facing? If the box is in a trunk, are there rear speakers that you can remove? Can you open up a ski pass/rear seat arm rest and cover it with a grill clothed screen?


As I said in my first post it's a Genesis coupe. The box is a sealed enclosure firing towards the rear. The trunk is decently sealed and sound stays inside without too much escaping.
I removed the stock 8" sub that sat in the rear deck so there is an opening from the trunk to the cabin, in the deck. I put sound dampening material on the top and bottom of the rear deck. There is no ski hole but the seats fold down in the back allowing full access to the trunk. I've noticed that putting the seat down doesn't make the subwoofers a whole lot louder. So the seats and hole in the rear deck must allow an ample amount of airflow for the sound to travel.


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## crazyirish (Jan 17, 2013)

Are you certain the stock headunit is sending enouh of a signal? I dont mean in terms of voltage, but in terms of frequency range. A buddy of mine has a single 13w7 running off of a similar wattage in his vehicle and it can easily get louder than i care to hear.


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## BuickGN (May 29, 2009)

You could always go ported and have just as good of sound quality and about the same additional output, maybe more, as adding another amp would get you. If you can give up a little extra space that is. Don't get caught up in the ported is for SPL and sealed is for SQ myth. W7s sound best in a larger than factory enclosure in most setups, FWIW.


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## NateZ28 (Oct 2, 2013)

crazyirish said:


> Are you certain the stock headunit is sending enouh of a signal? I dont mean in terms of voltage, but in terms of frequency range. A buddy of mine has a single 13w7 running off of a similar wattage in his vehicle and it can easily get louder than i care to hear.


In terms of frequency there is no cut off on the adapter. I am using the HD 750 low pass with the cut off set to 90 Hz.


BuickGN said:


> You could always go ported and have just as good of sound quality and about the same additional output, maybe more, as adding another amp would get you. If you can give up a little extra space that is. Don't get caught up in the ported is for SPL and sealed is for SQ myth. W7s sound best in a larger than factory enclosure in most setups, FWIW.


Are you sure ported would really sound as good as a sealed enclosure? Ported is usually optimized for a certain frequency range and doesn't allow for as accurate bass response a sealed enclosure. I don't have a whole lot of spae either...


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## minbari (Mar 3, 2011)

NateZ28 said:


> Are you sure ported would really sound as good as a sealed enclosure? Ported is usually optimized for a certain frequency range and doesn't allow for as accurate bass response a sealed enclosure. I don't have a whole lot of spae either...


again, that is a myth. they are not optimised for any frequency. they have a port that is tuned to a speicific frequency at which they resonate. all that means is you get nearly no woofer movement and more output from the port. at freq above the the tuning point they act very much like a sealed box.

all you have to be concerned with in a port box is freq under the tuning point, as a ported box will unload pretty fast. tune it low and use an appropriate SSF and you are golden.

ported boxes get bad rep because people either design or build them wrong. They also get a bad rep because SPL monsters use them for high output tuned at high freq, so people think they are not essque enough.


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## BuickGN (May 29, 2009)

NateZ28 said:


> In terms of frequency there is no cut off on the adapter. I am using the HD 750 low pass with the cut off set to 90 Hz.
> 
> Are you sure ported would really sound as good as a sealed enclosure? Ported is usually optimized for a certain frequency range and doesn't allow for as accurate bass response a sealed enclosure. I don't have a whole lot of spae either...


100% sure. Most ported boxes are tuned too high which can give more "free" output but gives the classic "boomy, slow, sloppy, one note wonder " sound. In most cases, depending on the car a low tune in the mid to high 20hz range will get you great SQ and sound just as good as the sealed box. Since excursion will be reduced near tuning frequency you can end up with lower distortion than the sealed box although the W7 is so linear over such a wide range it's not as big of a deal as it would be with an average sub. 

Either route you choose will work but going ported will be easier on the electrical system and cheaper. It really is a win-win as long as you can give up a little extra trunk space. I went infinite baffle because I didn't want to give up any trunk space but if I were going to use a box, it would be ported. 

Infinite baffle will get you more output in the lower frequencies and great SQ and you will get most of your trunk back. It might not be as much of a boost as you're looking for but you will definitely hear a difference in the frequencies that require the most power.


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## 07azhhr (Dec 28, 2011)

NateZ28 said:


> In terms of frequency there is no cut off on the adapter. I am using the HD 750 low pass with the cut off set to 90 Hz.
> 
> ...


What he is asking about is the factory HU itself sending a not so great signal down the signal chain. It could be possible that your HU has built in eq curves that pull bass as you turn up the volume. Mine did this in my HHR and even pulled bass when you faded to the rear. 

With my factory HU I needed 2 subs to get any decent bass. When I switched to my 80prs using the same amp I was able to delete on of the subs and still had almost the same output as both subs provided on the factory HU.


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## miniSQ (Aug 4, 2009)

BuickGN said:


> 100% sure. Most ported boxes are tuned too high which can give more "free" output but gives the classic "boomy, slow, sloppy, one note wonder " sound. In most cases, depending on the car a low tune in the mid to high 20hz range will get you great SQ and sound just as good as the sealed box. Since excursion will be reduced near tuning frequency you can end up with lower distortion than the sealed box although the W7 is so linear over such a wide range it's not as big of a deal as it would be with an average sub.
> 
> Either route you choose will work but going ported will be easier on the electrical system and cheaper. It really is a win-win as long as you can give up a little extra trunk space. I went infinite baffle because I didn't want to give up any trunk space but if I were going to use a box, it would be ported.
> 
> Infinite baffle will get you more output in the lower frequencies and great SQ and you will get most of your trunk back. It might not be as much of a boost as you're looking for but you will definitely hear a difference in the frequencies that require the most power.


you really can't be 100% that the OP is going to find the SQ of a ported box to be equal to his sealed.

Its going to sound louder, and its going to sound different. Those two you can say 100%. But you can't predict that OP is going to like it.


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## BuickGN (May 29, 2009)

miniSQ said:


> you really can't be 100% that the OP is going to find the SQ of a ported box to be equal to his sealed.
> 
> Its going to sound louder, and its going to sound different. Those two you can say 100%. But you can't predict that OP is going to like it.


Yes, I can, assuming it's tuned correctly for his setup. I know that ported can be every bit as punchy, quick, and whatever other adjectives you would use to describe a sub. Less distortion, better efficiency. Your theory would be like saying someone with a Kraco 6x9 might not like a Dyn Esotar 1200 better. Sure, maybe someone like that exists but it would be extremely uncommon. He seems to be worried about the accuracy in particular which is a non issue if the ported box is done right so yes, he will like it if he's like the other 99% of the population.


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## BuickGN (May 29, 2009)

07azhhr said:


> What he is asking about is the factory HU itself sending a not so great signal down the signal chain. It could be possible that your HU has built in eq curves that pull bass as you turn up the volume. Mine did this in my HHR and even pulled bass when you faded to the rear.
> 
> With my factory HU I needed 2 subs to get any decent bass. When I switched to my 80prs using the same amp I was able to delete on of the subs and still had almost the same output as both subs provided on the factory HU.


Good point for sure. I think he mentioned the amp cutting out at high volumes so assuming the install is good it sounds like a lack of power.


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## CrossFired (Jan 24, 2008)

4 gauge is small for that sort of power. When I wired up my little Boston 100x4 amp, I used 4 gauge, and the sound was thin. When I added a second run of 4 gauge, the amp really came alive.




NateZ28 said:


> Hmmm I had always been told that if two subs are running on separate amps they need separate enclosures. Otherwise you risk blowing a sub if one of the subs/amps stops playing, because one sub would have double the needed air space.
> Would I need to upgrade my power wire? Right now everything is 4 AWG running off the stock alternator and battery.


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## bassfromspace (Jun 28, 2016)

What processing do you have? As was stated earlier, your factory HU is likely rolling off the bass frequencies to save blown speakers.

Plug your phone or an Ipod directly into your sub amp's rca inputs and see what you get.


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## minbari (Mar 3, 2011)

CrossFired said:


> 4 gauge is small for that sort of power. When I wired up my little Boston 100x4 amp, I used 4 gauge, and the sound was thin. When I added a second run of 4 gauge, the amp really came alive.


Then you did something wrong. 4ga wire is good to 120 amps. No wayin your wettest dreams would a 400 watt amp pull even half than much current

sent from my phone using digital farts


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## .69077 (Aug 24, 2013)

minbari said:


> Then you did something wrong. 4ga wire is good to 120 amps. No wayin your wettest dreams would a 400 watt amp pull even half than much current
> 
> sent from my phone using digital farts


This. Im running a 900/5 with 4 gauge and no issues. Granted its a class D, but still.


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## ATOMICTECH62 (Jan 24, 2009)

In 2.5 cuft sealed 2 W-7 has a Qtc of .67 and an f3 of 45.4hz
In 2.5 cuft ported they have an f3 of 29.5hz with 5-6 more db between 30-50hz (3 cuft gross(2) 4"ports 25"long)


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## BuickGN (May 29, 2009)

ATOMICTECH62 said:


> In 2.5 cuft sealed 2 W-7 has a Qtc of .67 and an f3 of 45.4hz
> In 2.5 cuft ported they have an f3 of 29.5hz with 5-6 more db between 30-50hz (3 cuft gross(2) 4"ports 25"long)


Wouldn't that be the equivalent of quadruple the power?


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## CrossFired (Jan 24, 2008)

Your right, as I got mixed up on the gauge wire. I used 8 gauge, then a second run of 8 gauge.:surprised:



minbari said:


> Then you did something wrong. 4ga wire is good to 120 amps. No wayin your wettest dreams would a 400 watt amp pull even half than much current
> 
> sent from my phone using digital farts


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## thomasluke (Jun 10, 2011)

Still not gonna "wake it up".


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## CrossFired (Jan 24, 2008)

thomasluke said:


> Still not gonna "wake it up".


Well it did. Each 8 gauge run has a 40 amp fuse. When I pull one of the fuses while the system is playing, a lot of the bass go's away, and the sound gets rather thin sounding.


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## ImK'ed (Aug 12, 2013)

Then your positive must not be terminated right or theres alot of resistance, because if removing one fuse reduces the amount of current your amp can pull then certainly the single 40 amp should blow so seems you have resistance at your battery or amp, also check ground


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## 07azhhr (Dec 28, 2011)

BuickGN said:


> Good point for sure. I think he mentioned the amp cutting out at high volumes so assuming the install is good it sounds like a lack of power.


 
And his fix for the cutting out was to turn down the pot on the LOC which suggests that the input signal, after being turned down, would be even less thus adding to the issue.


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## ImK'ed (Aug 12, 2013)

The LOC could be causing the problem, most of these are cheapely made and destroy the fidelity of the signal, a good quality LOC or something like audiocontrol or cleansweep should be better but at a cost, im in the uk so dont know much about your car but some newer cars split the signal from headunit and send cut frequency to different speakers but if your using a sub out from stock headunit it should be ok. Best option in my opinion woul be to use a audiocontrol lcq1 as that will allow signal summing or when you use another amp for front stage and also it allows you to restore bass at high volume if its cut from stock headunit, ( cleansweep allows this aswel but you need a seperate signal summing device and you will have to use the master volume control of the cleansweep if your bass is cut at high volume, what you would do is set the volume at a certain level on headunit then calibrate cleansweep and use the cleansweeps volume )

With regards to your system cutting out have you got the amp input voltage selection correct? And is input to loc pre amp level? If you have a stock amp that should have pre amp level there .
HTH


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## miniSQ (Aug 4, 2009)

2 points that your installer shop should be aware of and i am curious as to if it was address. The JL HD amp is able to take a high level ( speaker level ) input by soldering RCA ends to the speaker level wires. This is how JL prefers these amps to be installed. This eliminates whatever LOC piece they installed.

also i believe that two HD amps can be piggybacked to power those subs in a single box. Because you are way underpowering 2 w7's with only a single HD750.

i am not impressed with your audio shop for not pointing these 2 things out to you.


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## ImK'ed (Aug 12, 2013)

^^^true! Plus if it was me i would have definetley used the signal before the stock amp (line level) and was the stock sub ran of this same factory amp or direcct of headunit?


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## bassfromspace (Jun 28, 2016)

Running speaker level to the amp still won't help if the HU is rolling off the bass. The HU will still need to be replaced, or a processor added to the system.


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## CrossFired (Jan 24, 2008)

ImK'ed said:


> Then your positive must not be terminated right or theres alot of resistance, because if removing one fuse reduces the amount of current your amp can pull then certainly the single 40 amp should blow so seems you have resistance at your battery or amp, also check ground


Removing one fuse, removes one of the 8 gauge wires. I'm running 4 ohms three way, so the amp is not working really hard. The resistance is increasing on one run of wire, when the second is disconnected.


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## ImK'ed (Aug 12, 2013)

Odd that 8 gauge isnt flowing enough current for less than 40 amps


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## ImK'ed (Aug 12, 2013)

Running speaker level to the amp wont fix bass roll off if he has that? But at least it eliminates the LOC, we need to know if the headunit has a dedicated sub out (if it does that shouldnt roll off) or if it was run off stock amp with simple 4 channel inputs


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## miniSQ (Aug 4, 2009)

bassfromspace said:


> Running speaker level to the amp still won't help if the HU is rolling off the bass. The HU will still need to be replaced, or a processor added to the system.


Are we sure that the HU is rolling off the bass? Maybe i missed a post that said it was measurably rolled off?

My 2013 hyundai elantra GT ( with nav), does not roll off the bass on the front speakers.


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## miniSQ (Aug 4, 2009)

CrossFired said:


> 4 gauge is small for that sort of power. When I wired up my little Boston 100x4 amp, I used 4 gauge, and the sound was thin. When I added a second run of 4 gauge, the amp really came alive.


#doubtful #edit #notthefirsttonotice

sorry, i guess others called this BS too 

gotta stop using hashtags LOL


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## CrossFired (Jan 24, 2008)

ImK'ed said:


> Odd that 8 gauge isnt flowing enough current for less than 40 amps


It is odd. Thats why I went with 8 gauge, as the chart showed it as adequate.

It may be the boston amp having dual taps for power and ground. May be the circuit board trace is too thin, when running a single tap.


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## ImK'ed (Aug 12, 2013)

Dual taps? You mean it has two positives and two grounds?


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## NateZ28 (Oct 2, 2013)

My 2010 Genesis Coupe has the Infinity sound system which uses a factory amplifier for all speakers. I suppose it is possible the head unit rolls off the bass for the pitiful stock sub that was in the car, if the stock amp has no frequency cut offs.
The RCA adapter taps into the head unit's output. 

I guess what I could try is getting a headphone splitter, using a 3.5 male to stereo L/R females, then run the stereo L/R to the RCA's that go to the HD amp. That would eliminate the head unit for the subwoofers. Regardless I plan to replace the head unit in about a week anyways.


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## CrossFired (Jan 24, 2008)

ImK'ed said:


> Dual taps? You mean it has two positives and two grounds?


Yes.


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## ImK'ed (Aug 12, 2013)

Wow why is it two amps in one?


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## CrossFired (Jan 24, 2008)

ImK'ed said:


> Wow why is it two amps in one?


No, I just think it's very under rated.


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## ImK'ed (Aug 12, 2013)

Ok so the stock amp feeds subs and speakers,i would splice in before amp and strainght to rca no LOC, what i did on my car ( honda type r ) with stock headunit is remove a speaker or in your case either the inputs to amp or sub output from amp or if the headunit has a sub out, connect a voltmeter and play a sine wave 40 50 60hz and watch voltmeter as you increase volume and see if it stops rising before max volume, or simply play sine wave with sub connected stock sub and listen while increasing volume and see if sub starts going down in volume or stops getting louder


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## NateZ28 (Oct 2, 2013)

ImK'ed said:


> Ok so the stock amp feeds subs and speakers,i would splice in before amp and strainght to rca no LOC, what i did on my car ( honda type r ) with stock headunit is remove a speaker or in your case either the inputs to amp or sub output from amp or if the headunit has a sub out, connect a voltmeter and play a sine wave 40 50 60hz and watch voltmeter as you increase volume and see if it stops rising before max volume, or simply play sine wave with sub connected stock sub and listen while increasing volume and see if sub starts going down in volume or stops getting louder


I think I'll just bypass the head unit and send the full range of sound from my iPhone directly to the subs through the RCA's, using a headphone splitter. 
*Question:* Should I also bypass the RCA adapter that controls voltage? I believe that controls the Voltage the amp receives and I'm sure the voltage ouput from the iPhone headphone out is probably not enough


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## ImK'ed (Aug 12, 2013)

Yes bypass the rca adapter as that converts high level to low level (line level) and connect phone directly to amp and see if it bumps, what i mean is before the stock amp that is line level i would splice an rca and put that straight to amp but make sure input voltage selection is set to low


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## NateZ28 (Oct 2, 2013)

ImK'ed said:


> Yes bypass the rca adapter as that converts high level to low level (line level) and connect phone directly to amp and see if it bumps, what i mean is before the stock amp that is line level i would splice an rca and put that straight to amp but make sure input voltage selection is set to low


But isn't the voltage from the iPhone headphone out too low?


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## t3sn4f2 (Jan 3, 2007)

NateZ28 said:


> *As I said in my first post it's a Genesis coupe.* The box is a sealed enclosure firing towards the rear. The trunk is decently sealed and sound stays inside without too much escaping.
> I removed the stock 8" sub that sat in the rear deck so there is an opening from the trunk to the cabin, in the deck. I put sound dampening material on the top and bottom of the rear deck. There is no ski hole but the seats fold down in the back allowing full access to the trunk. I've noticed that putting the seat down doesn't make the subwoofers a whole lot louder. So the seats and hole in the rear deck must allow an ample amount of airflow for the sound to travel.


Will you look at that.....you did say it. I missed it completely. Well looks like you go it under control. Good luck to ya!


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## bassfromspace (Jun 28, 2016)

NateZ28 said:


> But isn't the voltage from the iPhone headphone out too low?


Potentially, but should be sufficient enough to tell you if the HU is the culprit.


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## edzyy (Aug 18, 2011)

Surprised no one mentioned

...infinite baffle.

DO IT


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## NateZ28 (Oct 2, 2013)

I paid way too much for this box so I'd rather not ditch it.


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## FocalG8 (Feb 10, 2013)

I'm running a 750/1 on a single focal 27v2. Its nowhere near enough power for 2 10W7s. One per woofer would be better for sure. I installed JL gear for years and the W6v2 is good on 5-600 watts each. The W7s need more around 1000 each to really come alive.


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## Coolcolombian (Mar 12, 2009)

edzyy said:


> Surprised no one mentioned
> 
> ...infinite baffle.
> 
> DO IT


So are you recommending a 10W7 in IB application? The reason I want to dig more into this option is because I have one on a pro wedge sealed box powered by an Alpine V9 putting about 560W to the sub and it is not as loud as I would like it to be and I keep wondering how would it perform if I install it on the rear deck IB. Sorry for the thread jack.


Sent from my iPad using Tapatalk - now Free


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## NateZ28 (Oct 2, 2013)

FocalG8 said:


> I'm running a 750/1 on a single focal 27v2. Its nowhere near enough power for 2 10W7s. One per woofer would be better for sure. I installed JL gear for years and the W6v2 is good on 5-600 watts each. The W7s need more around 1000 each to really come alive.


The 10W7 is rated for 750 watts RMS. I would rather not exceed that and risk harming the sub and voiding the warranty.


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## minbari (Mar 3, 2011)

Coolcolombian said:


> So are you recommending a 10W7 in IB application? The reason I want to dig more into this option is because I have one on a pro wedge sealed box powered by an Alpine V9 putting about 560W to the sub and it is not as loud as I would like it to be and I keep wondering how would it perform if I install it on the rear deck IB. Sorry for the thread jack.
> 
> 
> Sent from my iPad using Tapatalk - now Free


That much power IB should push it to xmax easy.

sent from my phone using digital farts


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## miniSQ (Aug 4, 2009)

NateZ28 said:


> The 10W7 is rated for 750 watts RMS. I would rather not exceed that and risk harming the sub and voiding the warranty.


its called head room, and you need to at least double your power on those subs, as you are hearing in your car, but not hearing in your thread.


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## FocalG8 (Feb 10, 2013)

We often ran 2250w amps on a pair of these. You just have to set it up right. I would be willing to bet one of these with that amp would be better than 2 on the amp for sq and output.


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## NateZ28 (Oct 2, 2013)

miniSQ said:


> its called head room, and you need to at least double your power on those subs, as you are hearing in your car, but not hearing in your thread.


I understand and agree with what everyone is saying. I think using two HD 750's will be enough honestly. I don't need them to go that much louder.


FocalG8 said:


> We often ran 2250w amps on a pair of these. You just have to set it up right. I would be willing to bet one of these with that amp would be better than 2 on the amp for sq and output.


What amp is that? Because a lot of amps are rated in peak power and don't reach what they claim for RMS.
Why do you say that the single amp would be better for SQ?


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## NateZ28 (Oct 2, 2013)

I tried directly connecting my iPhone to the HD 750. It is louder. But I feel I would like it a bit louder. How much louder will it be with a proper head unit (Pioneer 80PRS)?


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## edzyy (Aug 18, 2011)

Coolcolombian said:


> So are you recommending a 10W7 in IB application? The reason I want to dig more into this option is because I have one on a pro wedge sealed box powered by an Alpine V9 putting about 560W to the sub and it is not as loud as I would like it to be and I keep wondering how would it perform if I install it on the rear deck IB. Sorry for the thread jack.
> 
> 
> Sent from my iPad using Tapatalk - now Free


dont put it in the rear deck

Put it on a baffle behind the rear seat


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## BuickGN (May 29, 2009)

BuickGN said:


> Infinite baffle will get you more output in the lower frequencies and great SQ and you will get most of your trunk back. It might not be as much of a boost as you're looking for but you will definitely hear a difference in the frequencies that require the most power.


I mentioned IB a while ago. 

750w should get both to xmax. I've said it a thousand times but the W6/7 sound very nice IB, better than sealed.


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## NateZ28 (Oct 2, 2013)

So what about the HD 1200? My audio shop may allow me to pay the difference to upgrade.


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## ATOMICTECH62 (Jan 24, 2009)

That is only going to give you about 1 db more output.From your description you will need way more then that.
If you came to me with this problem,first thing I would do is confirm the audio signal and amp are not at fault.If thats all good,I would pull the box and port it.I know this will give you about 6 db more and lower extension.If I had to I would build a smaller box(1-2 cuft)and add it to the box for even more output,and larger ports if needed.Then increase amp power.Next step would be (2) 12's.


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## NateZ28 (Oct 2, 2013)

ATOMICTECH62 said:


> That is only going to give you about 1 db more output.From your description you will need way more then that.
> If you came to me with this problem,first thing I would do is confirm the audio signal and amp are not at fault.If thats all good,I would pull the box and port it.I know this will give you about 6 db more and lower extension.If I had to I would build a smaller box(1-2 cuft)and add it to the box for even more output,and larger ports if needed.Then increase amp power.Next step would be (2) 12's.


Well with the back seats down and the iPhone directly connected to the subs it's getting closer to what I'm looking for. How much louder will it be with the head unit?
Am I losing any sound quality with the HD 750?


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## ATOMICTECH62 (Jan 24, 2009)

Well,If you were wanting to change the HU then I would agree we should swap it out first and go from there.Like I said,thats the first thing that needs confirmed.That could solve the whole problem.If not,then I would move to the next step.Those w7's are right down the middle of the road between sealed or ported.They can do both well.I personally like ported if possible because of the extra output.But since you already paid to have it made there is since in throwing more money at it.You want the pioneer anyway and it will be a big upgrade in SQ all the way around.
If that solves the problem then changing the amp would make a much bigger improvement then if it didnt because now things are working like they should.Sometimes speakers need power to make them come alive,but I dont think that is going to help if something else is wrong.


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## ImK'ed (Aug 12, 2013)

One thing have you adjusted the input sensitivity on your amp to match iphone? But personaly i would think a hd 1200/1 would and should be enough, im running a pdx m12 set to make around 1000wrms to a single 12 alpine swr 12d2 and that is more than loud and yours with 1200wrms on two 10w7s probably has near enough twice the cone area, personaly i think two 10w7s on a hd1200 would be my perfect sub stage if i had the funds


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## miniSQ (Aug 4, 2009)

NateZ28 said:


> So what about the HD 1200? My audio shop may allow me to pay the difference to upgrade.


i would swap down to a pair of w6's and up to the 1200/1. If they would let you do both

If not, save up for a second 750/1.


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## NateZ28 (Oct 2, 2013)

So am I losing SQ with my setup (HD 750 and 2x 10W7) or just loudness?


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## BuickGN (May 29, 2009)

miniSQ said:


> i would swap down to a pair of w6's and up to the 1200/1. If they would let you do both
> 
> If not, save up for a second 750/1.


Why would you downgrade to a W6?


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## bassfromspace (Jun 28, 2016)

The 750 should be plenty for two W7's in a hatch. My next step would be a HU or outboard processor.


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## NateZ28 (Oct 2, 2013)

BuickGN said:


> Why would you downgrade to a W6?


I agree, I've wanted a W7 for years because of their legendary sound.


bassfromspace said:


> The 750 should be plenty for two W7's in a hatch. My next step would be a HU or outboard processor.


It's a coupe, not a hatch.
The Pioneer 80PRS has been ordered. It will be installed this Saturday. Should I sound dampen the trunk? My audio installer claimed they didn't think it was needed. The sound seems to stay in the trunk for the most part and vibration is minimal.

Again one member on here claimed I was loosing SQ with this amp, could that be true?


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## ATOMICTECH62 (Jan 24, 2009)

No.You are not loosing SQ.JL makes some of the best Class D amps out there.Could you use more power?Yes.But that will only give you a few more DB's.
I think he was thinking in the terms of the subs can take more power and if your not maxing them out you are at a loss.
Its like saying "My 71 Chevy Nova has a 350 small block.Am I loosing horse power?


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## NateZ28 (Oct 2, 2013)

ATOMICTECH62 said:


> No.You are not loosing SQ.JL makes some of the best Class D amps out there.Could you use more power?Yes.But that will only give you a few more DB's.
> I think he was thinking in the terms of the subs can take more power and if your not maxing them out you are at a loss.
> Its like saying "My 71 Chevy Nova has a 350 small block.Am I loosing horse power?


Thanks that's what I thought. I appreciate getting confirmation.
So you think it would not be worth it to upgrade to the HD 1200? What are my options after getting the new head unit for making the subs louder? Has anyone had success with cutting up their rear deck?


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## minbari (Mar 3, 2011)

upgrading to a 1200 watt or adding a second 750 is going to give you more headroom, but not night and day difference in SPL. 3db MAX. everyone keeps saying that 350 watts in (2) 12" subs is nothing. that is a good amount of power. could they accpet more power?, yes, but its not going to make a huge difference.

as Atomictech said, if you have a car with a 350cuin engine and you never push the engine to the max does that mean you have a bad car?


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## BuickGN (May 29, 2009)

On many unibody cars the deck is a structural member. I wouldn't go too crazy. How thick are the rear seats? Mine are pretty padded and they let bass through easily. They tend to limit the upper end response a little.


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## bassfromspace (Jun 28, 2016)

NateZ28 said:


> I agree, I've wanted a W7 for years because of their legendary sound.
> 
> It's a coupe, not a hatch.
> The Pioneer 80PRS has been ordered. It will be installed this Saturday. Should I sound dampen the trunk? My audio installer claimed they didn't think it was needed. The sound seems to stay in the trunk for the most part and vibration is minimal.
> ...


Sorry.

I would get the HU in and fine tune it before adding anything else into the mix. Even dampening.


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## Schizm (Jun 12, 2011)

Lining the trunk is more for damping resonance and annoying body panel vibration isnt it? It wouldn't help increase perceived bass (quality and loudness) inside the cabin of the vehicle.


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## NateZ28 (Oct 2, 2013)

BuickGN said:


> On many unibody cars the deck is a structural member. I wouldn't go too crazy. How thick are the rear seats? Mine are pretty padded and they let bass through easily. They tend to limit the upper end response a little.


Here's my seats:








As you can see there is no seat in the middle. So I could do something like cut out the center seat and create an opening, but that might be a pain.

Here they are folded down:








There is a plastic cover on the back of the seats that is most likely not helping the sound get through.


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## miniSQ (Aug 4, 2009)

sound level wise...how does it sound with seats up vs seats down? with seats up you might also try a shallower XO slope...like 12db.


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## gijoe (Mar 25, 2008)

Looking at the pictures of your trunk/back seats makes me jealous. You could do IB in that car so easily that I wouldn't think twice. Building the baffle in my impreza was incredibly complex compared to what it would be for you. You're not going to get a car that's much easier to go IB in than that. I say go IB.


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## NateZ28 (Oct 2, 2013)

I paid $400 for this "custom built" sealed box...


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## miniSQ (Aug 4, 2009)

NateZ28 said:


> I paid $400 for this "custom built" sealed box...


this post is worthless without pictures


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## gijoe (Mar 25, 2008)

NateZ28 said:


> I paid $400 for this "custom built" sealed box...


That's a lot of cash, hopefully you can figure out how to get the sound that you want without ditching the pieces that cost you so much money.


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## thomasluke (Jun 10, 2011)

NateZ28 said:


> I paid $400 for this "custom built" sealed box...


You need to do everything you can to work with this shop to get the sound you want.
You have a lot invested in it already. Hopefully they will be understanding and help you out.


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## NateZ28 (Oct 2, 2013)

miniSQ said:


> this post is worthless without pictures


I can post pics but it's really just a basic sealed box built to JL's specs for two 10W7's. It's braced internally and has a partial divider for support with 2.5 ft³ of air space.


thomasluke said:


> You need to do everything you can to work with this shop to get the sound you want.
> You have a lot invested in it already. Hopefully they will be understanding and help you out.


I have and I think the new head unit will really bring the system to life. At least I hope. I'm still getting used to the sound of the W7's. They hit hard and accurately. I'm used to feeling more of the bass. Before this I had two Rockford Fosgate P3 12's in a ported box.

Is there any way I can "feel the bass" more without changing the enclosure?


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## miniSQ (Aug 4, 2009)

NateZ28 said:


> Is there any way I can "feel the bass" more without changing the enclosure?


i believe captain kirk said it best...


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## ImK'ed (Aug 12, 2013)

Jus re read posts, defo wait until headunit is installed that will give you a good source and straight path to amps, make sure they feed a remote lead and 3 rcas aswel , personally i would go with hd1200/1 and 600/4 and sit back and enjoy


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## miniSQ (Aug 4, 2009)

NateZ28 said:


> I can post pics but it's really just a basic sealed box built to JL's specs for two 10W7's. It's braced internally and has a partial divider for support with 2.5 ft³ of air space.


by seeing it , it may be possible to suggest a different way to put it in the trunk. i would suggest it be firing toward the rear of the vehicle instead of say firing up. That generally gets you the most impact in a trunk.

You may also want to double check that the shop wired the two subs properly and that one is not out of phase.

How much stuffing did they use? And what is the crossover point and slope?


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## NateZ28 (Oct 2, 2013)

miniSQ said:


> by seeing it , it may be possible to suggest a different way to put it in the trunk. i would suggest it be firing toward the rear of the vehicle instead of say firing up. That generally gets you the most impact in a trunk.
> 
> You may also want to double check that the shop wired the two subs properly and that one is not out of phase.
> 
> How much stuffing did they use? And what is the crossover point and slope?


I can supply a picture shortly. They are firing towards the rear of the car. 
They did not use any kind of stuffing in the box. The crossover is set to 90 Hz with a 12 dB slope.


ImK'ed said:


> Jus re read posts, defo wait until headunit is installed that will give you a good source and straight path to amps, make sure they feed a remote lead and 3 rcas aswel , personally i would go with hd1200/1 and 600/4 and sit back and enjoy


Why 3 RCA's if I'm only using two amps?


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## ImK'ed (Aug 12, 2013)

3 rcas = front rear sub or 3way highs mid sub


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## miniSQ (Aug 4, 2009)

NateZ28 said:


> I can supply a picture shortly. They are firing towards the rear of the car.
> They did not use any kind of stuffing in the box. The crossover is set to 90 Hz with a 12 dB slope.


If it were me, i would lower the crossover to 75hz and check the output with a DMM to see if i could bump up the gains a little.

Have you checked the output yet? Its possible they have the gains set wrong, i know that the gains are not a volume control. but the reality is that turning the gain up gives you more bass.

I would also verify they built the box to 2.5 cuft with a tape measure. And i would be tempted to add some stuffing when i popped out the drivers to check the wiring


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## danno (Jan 25, 2009)

If they used signal from the oem sub out, that is why you're unhappy with it. Not enough range. You need to use the front door woofers and the sub signal.


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## NateZ28 (Oct 2, 2013)

ImK'ed said:


> Jus re read posts, defo wait until headunit is installed that will give you a good source and straight path to amps, make sure they feed a remote lead and 3 rcas aswel , personally i would go with hd1200/1 and 600/4 and sit back and enjoy





miniSQ said:


> If it were me, i would lower the crossover to 75hz and check the output with a DMM to see if i could bump up the gains a little.
> 
> Have you checked the output yet? Its possible they have the gains set wrong, i know that the gains are not a volume control. but the reality is that turning the gain up gives you more bass.
> 
> I would also verify they built the box to 2.5 cuft with a tape measure. And i would be tempted to add some stuffing when i popped out the drivers to check the wiring


JL told me to set it between 80-100 Hz to compensate for the lack of mid bass in the stock system. I'm going to have the audio shop retune the amp when the 80PRS is installed this weekend.
I asked about using stuffing and the shop said they tested it and found it to be generally "useless".


danno said:


> If they used signal from the oem sub out, that is why you're unhappy with it. Not enough range. You need to use the front door woofers and the sub signal.


Right now I have the subs directly connected to my iPhone so they are getting the full range. In a few days they will have a direct connection to the new Pioneer 80PRS.


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## minbari (Mar 3, 2011)

NateZ28 said:


> JL told me to set it between 80-100 Hz to compensate for the lack of mid bass in the stock system. I'm going to have the audio shop retune the amp when the 80PRS is installed this weekend.
> *I asked about using stuffing and the shop said they tested it and found it to be generally "useless".*
> 
> Right now I have the subs directly connected to my iPhone so they are getting the full range. In a few days they will have a direct connection to the new Pioneer 80PRS.


then I would find a new shop 

it is a proven technique


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## edzyy (Aug 18, 2011)

400 for a sealed box?


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## miniSQ (Aug 4, 2009)

minbari said:


> then I would find a new shop
> 
> it is a proven technique


i disagree...stuffing is not cut and dried, and in fact its easily proven to be useless in subwoofer enclosures.

But lets agree to disagree and move on, this is not relevant to the OP. He is not going to gain the type of output he is looking for by adding stuffing.


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## NateZ28 (Oct 2, 2013)

minbari said:


> then I would find a new shop
> 
> it is a proven technique


I'm not arguing with you but JL didn't recommend using it either, as long as the box is built to their specs.


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## NateZ28 (Oct 2, 2013)

edzyy said:


> 400 for a sealed box?


It's expensive for a box but I wanted it done right and they did a good job. I also got a very good deal on the W7's, so the price I paid for the box didn't hurt as much.


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## minbari (Mar 3, 2011)

miniSQ said:


> i disagree...stuffing is not cut and dried, and in fact its easily proven to be useless in subwoofer enclosures.
> 
> But lets agree to disagree and move on, this is not relevant to the OP. He is not going to gain the type of output he is looking for by adding stuffing.


you never know, with a 2.5cuft box an additional 20-30% of volume might give exactly what he wants.

as for it not being cut and dried. here is a pretty well done article by a very well respected man that has results that are pretty hard to argue with.

http://www.nousaine.com/pdfs/Box Stuffing.pdf


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## drowssap (Oct 23, 2013)

I am running just one 10W7 in a 2013 prius using an HD750/1. I have the factory HU but using a clean sweep. Regardless of the clean sweep...the HU still sends a crappy signal and my 10 in a sealed enclosure POUNDS!! I am a newbie but as soon as I figure out how to post up pics I will but regardless of all that....these subs are thirsty for power and I cannot see running two of these off of just one of these amps. But then again what do I know! This is why I joined this forum....to learn from the guys that do know!


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## NateZ28 (Oct 2, 2013)

So the audio shop says that even if I go active with the subs using the 80PRS that I should still set the low pass frequency cut off on the HD 750. They said to turn the frequency cut off all the way up on the amp, just in case the battery dies and the head unit resets. 
They said that otherwise the subs could be damaged if they tried to play the full range of sound.


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## drowssap (Oct 23, 2013)

Well....that is kind of true to my limited knowledge. I think that only comes into play if you don't have a dsp or if your HU does not have the ability to set the freq. for sub out.


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## ATOMICTECH62 (Jan 24, 2009)

That makes no sense.


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## drowssap (Oct 23, 2013)

The purpose of the hpf and lpf on amps are to set the freq sent to the speakers. If you have a dsp or a head unit that can set those freq and specifically send that signal....isn't that possible to eliminate the imprint from the amp? Seriously am trying to learn the right answer...not trying to actually answer!


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## ATOMICTECH62 (Jan 24, 2009)

Yup,with the crossover in the deck the one in the amp can be bypassed.But sometimes if needed both can be used.They can be used for steeper slopes or bandpass if possible.


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## NateZ28 (Oct 2, 2013)

ATOMICTECH62 said:


> Yup,with the crossover in the deck the one in the amp can be bypassed.But sometimes if needed both can be used.They can be used for steeper slopes or bandpass if possible.


The shop claims that if the amp is set to full with no frequency cut off and the head unit resets, because the battery dies, the subs will try to play the full range of sound. 
Usually if your battery dies and the head unit resets the frequency cut offs are reset to default.

The shop is saying to still use some frequency cut off at the amp only as a safety feature to protect the subs. Setting the low pass cut off to maximum, 500 Hz on the HD 750, should not conflict with the head unit Xover correct?


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## t3sn4f2 (Jan 3, 2007)

Speakers don't blow from playing too high, they blow from playing too low. They fail mechanically from over excursion not from thermal overload. Don't listening too much to what that shop is telling you when it comes to advanced system and active setups.


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## Golden Ear (Oct 14, 2012)

Has anyone used winisd to see what the ideal sealed enclosure is for this sub yet?


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## NateZ28 (Oct 2, 2013)

The 80PRS did a great job of enhancing the sound in my car. The bass is pretty loud, but I have to set it to +5 or +6 Db in the sub settings. The Auto tune is also interesting. Everything seems louder with it on. 

Now I need to get new speakers. I'm considering the Focal KRX2's, but I'm worried about them being too bright. Anyone have any advice there? Golden Ear are you in any way associated with the company Golden Ear?

Here's my newest topic for picking out my components: http://www.diymobileaudio.com/forum...-components-my-genesis-coupe.html#post1988156


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## Golden Ear (Oct 14, 2012)

NateZ28 said:


> Now I need to get new speakers. I'm considering the Focal KRX2's, but I'm worried about them being too bright. Anyone have any advice there? Golden Ear are you in any way associated with the company Golden Ear?


Lol No, I'm just really full of myself:laugh:

I also have an 80prs and I really enjoy it. I no longer use the autotune but when I did it was pretty good. It's a great way to start off an active setup. You can switch it to network mode and do a 3-way setup, perfect f you're going to run a 2-way comp set up front.


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## NateZ28 (Oct 2, 2013)

Golden Ear said:


> Lol No, I'm just really full of myself:laugh:
> 
> I also have an 80prs and I really enjoy it. I no longer use the autotune but when I did it was pretty good. It's a great way to start off an active setup. You can switch it to network mode and do a 3-way setup, perfect f you're going to run a 2-way comp set up front.


What speakers do you have?


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## Golden Ear (Oct 14, 2012)

NateZ28 said:


> What speakers do you have?


I'm now running a Mosconi DSP 4to6 with a pair of NZ3 3" wideband speakers in custom dash pods and 7" Dayton Audio RS180-4s in the doors. I would have kept using the 80prs for my active setup but the crossover for the tweeters only goes down to 1.2khz, iirc, and my 3s are crossed at 250hz playing up to 20khz.


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## NateZ28 (Oct 2, 2013)

Golden Ear said:


> I'm now running a Mosconi DSP 4to6 with a pair of NZ3 3" wideband speakers in custom dash pods and 7" Dayton Audio RS180-4s in the doors. I would have kept using the 80prs for my active setup but the crossover for the tweeters only goes down to 1.2khz, iirc, and my 3s are crossed at 250hz playing up to 20khz.


Interesting setup. I have limited space in my coupe so I may just go with components for now. Have you ever listened to Focal KRX2's running active?


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## Golden Ear (Oct 14, 2012)

NateZ28 said:


> Interesting setup. I have limited space in my coupe so I may just go with components for now. Have you ever listened to Focal KRX2's running active?


Sorry, I've never heard them. I had a set of the Polyglass 165v2s and they sounded pretty good. I know they are a couple steps down from those KRX2s so I'd bet the KRX2s will sound real good. Where are you gonna put the tweeter and mid?


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## sqshoestring (Jun 19, 2007)

NateZ28 said:


> The shop claims that if the amp is set to full with no frequency cut off and the head unit resets, because the battery dies, the subs will try to play the full range of sound.
> Usually if your battery dies and the head unit resets the frequency cut offs are reset to default.
> 
> The shop is saying to still use some frequency cut off at the amp only as a safety feature to protect the subs. Setting the low pass cut off to maximum, 500 Hz on the HD 750, should not conflict with the head unit Xover correct?


What bunch of morons, they think a tweeter/mid signal is going to hurt a 750w sub? They really are stupid.

Anyway, I've killed my 880prs a few times (er, killed the battery) and it only loses the radio stations lol. However all this demo garbage comes on and the display blinks bright and dark and all that, bright fellow that programmed that thing its near dangerous at night. The xover/levels/TA/EQ all stay but everything else dies. Suppose a P80 may be different.

Most people want to use the HU xover LP for the sub when they have a good HU, so they turn the amp xover high as it goes so it does not interfere. Typical that class D sub amps the LP does not go that high I think mine is 200 on this older alpine. If you set both to the same value (you should test to make sure the amp is LP where it says, especially if not digital) it will double the slope, that can be a useful tool at times.

I would def get the HU in and see what you have then.


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## Serieus (May 27, 2011)

i've disconnected the battery numerous times and my sound settings always stay on the 80prs, but it does do the stupid demo mode


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## NateZ28 (Oct 2, 2013)

sqshoestring said:


> What bunch of morons, they think a tweeter/mid signal is going to hurt a 750w sub? They really are stupid.
> 
> Anyway, I've killed my 880prs a few times (er, killed the battery) and it only loses the radio stations lol. However all this demo garbage comes on and the display blinks bright and dark and all that, bright fellow that programmed that thing its near dangerous at night. The xover/levels/TA/EQ all stay but everything else dies. Suppose a P80 may be different.
> 
> ...


You have to understand the kind of people that live here in Tampa, Florida. Most of the people buying aftermarket systems here want to play it obscenely loud. At least the people I've met and the shop has come across. They turn the volume to max and bass boost everything to ****. I've gotten into several of my friend's cars and they are playing the music so loud all of the speakers are clipping, but they think that because it's loud it sounds good. It is possible to blow subwoofers, especially cheaper one's, playing at higher frequencies. This is because with the lack of excursion the subwoofer is unable to cool itself. Unless it uses pole vent cooling or a similar method. But at roughly 400 watts RMS per W7 I doubt it's possible.
As a rule of thumb the shop is overly cautious. I have seen them build some extremely impressive systems. If I'm ever unhappy with anything I go back in and they fix it for me free of charge. They fixed a lot of rattles in the car for free and I haven't paid to dampen all of it yet. The shop is called Maximum Audio Video.

But to switch gears here; I have an idea for something unique, but probably not new. I have a plan to make a circular hole in the center of the rear seat. Possibly hollowed out with fiberglass. That think it would really bring the subs into the cabin. I'll do this once I purchase components that can keep up with the subwoofers.


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## t3sn4f2 (Jan 3, 2007)

Why Do Tweeters Blow When Amplifiers Distort?

"*Power Distribution* 

A great part of the mystery is uncovered when we look at two aspects of music - the average versus peak power, and the energy distribution of typical music material.

It is commonly accepted (and quite valid) that music has a peak to average ratio of about 10-20dB. This means that if the signal is being amplified by a typical 100W amplifier, the amp's power rating limits the absolute maximum power to 100W (give or take a little). Since this is the peak, the average must be somewhat lower, and we will assume 10dB for the sake of convenience. Average power is therefore 10W or less at the onset of clipping.

This is not dynamic range per sé, but it is most certainly a part of the overall dynamic range of the music signal. The term 'dynamic range' usually refers to the very quietest up to the very loudest passages in a given piece of music. In some cases, there is no variation whatsoever - it starts loud, is loud in the middle, and (just to be different) finishes ... loud. The peak to average level may also be compressed, but it is difficult to reduce it to less than 10dB without it becoming flat and lifeless. If done incorrectly, it can simply become a jumbled mess with no intelligibility whatsoever (and no, I'm not going to take this to its logical conclusion and denounce various styles that may be classified as music to only a select few )

Most speakers are rated for a continuous power and an instantaneous power - the voice coil and to a lesser degree the suspension can withstand short bursts at much higher powers without damage. This does not imply that such power will be reproduced cleanly, and it will almost certainly be with a large increase in distortion. The peak power rating defines the maximum transient power the loudspeaker can handle without suffering electrical or mechanical (stress induced) damage.

*Nearly all tweeters are rated to 'system power', and this will usually be quoted relative to a specific crossover frequency. A hypothetical tweeter may be rated at 100W system power when crossed over at 3,000Hz. The power that it can withstand is not 100W! Not at any frequency or for any duration.*










Figure 1 - Power Distribution Chart

*The above power distribution table is approximate (as must be the case), and applies for 'typical' music - whatever that may be. If we look at the case for a crossover frequency of 3kHz, we can see that 85% of the power is in the low frequency spectrum, and only 15% in the high frequencies above 3kHz. It is not difficult to deduce from this that the peak power to the tweeter will be in the order of 15W at full power from the amplifier, with the average at about 1.5W*This is the way the system was designed to be used, and as long as the power amp does not clip, all is well (well, almost - read on)."


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## NateZ28 (Oct 2, 2013)

Golden Ear said:


> Sorry, I've never heard them. I had a set of the Polyglass 165v2s and they sounded pretty good. I know they are a couple steps down from those KRX2s so I'd bet the KRX2s will sound real good. Where are you gonna put the tweeter and mid?


Most likely in the stock location. I could go 3 way, but it would be more work and definitely cost more money.


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## NateZ28 (Oct 2, 2013)

I noticed this morning when playing an 80 Hz test tone that my sub is pretty quiet at 80 Hz+. If I have the crossover set to 80 Hz shouldn't the subwoofer being playing that frequency at nearly an equal volume as say 60 Hz?


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## Golden Ear (Oct 14, 2012)

NateZ28 said:


> I noticed this morning when playing an 80 Hz test tone that my sub is pretty quiet at 80 Hz+. If I have the crossover set to 80 Hz shouldn't the subwoofer being playing that frequency at nearly an equal volume as say 60 Hz?


Not necessarily. That's where tuning comes in. Go to the Graphic Equalizer 2 menu and try raising 80hz to your liking.


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## NateZ28 (Oct 2, 2013)

Golden Ear said:


> Not necessarily. That's where tuning comes in. Go to the Graphic Equalizer 2 menu and try raising 80hz to your liking.


So the subwoofer shouldn't naturally extend into that range? It seems like it's falling off past 65 Hz even if I set the LP to 100 Hz.


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## Golden Ear (Oct 14, 2012)

I was having trouble with my hd1200/1 and found out that the crossover should be off on it since I have a dsp. The 80prs has a built in dsp so try turning the crossover section off on your amp and see what it does. It should be off anyway.


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## miniSQ (Aug 4, 2009)

Golden Ear said:


> I was having trouble with my hd1200/1 and found out that the crossover should be off on it since I have a dsp. The 80prs has a built in dsp so try turning the crossover section off on your amp and see what it does. It should be off anyway.


This is good advice...or leave the LP filter on but turn it up to 250hz or whatever the max is. This way you can still take advantage of some of the bass tuning capabilities of the JL amp...if it has any. My 500/1 has some nice parametric EQ stuff it does, but that goes away if i just just the LP filter off, so i max out the LP filter setting and control the XO with the DSP.


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## NateZ28 (Oct 2, 2013)

Golden Ear said:


> I was having trouble with my hd1200/1 and found out that the crossover should be off on it since I have a dsp. The 80prs has a built in dsp so try turning the crossover section off on your amp and see what it does. It should be off anyway.


I think it's set to 125 Hz 12 dB curve right now. Would it still be effecting the subs if the head unit is set to 100 Hz, 12 DB curve?
What exactly is the amp doing other than acting as a crossover?


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