Looking for opinions on my orientation.

[JW266]

Backseat in this car was useless so this is happening. I had been running a single sub downfiring on the passenger side it sounded good. But the install was janky. Is there any reason I shouldn't just wrap it and glass it? Doing the downfiring thing would just require more box building that I don't wanna do. Also like idea of being able to toss a hood or 2 in the back to hide them if I'm ever in that part of town.

Should I aim them any differently?

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[hispls 5,000+ posts]

Flat wall is generally optimum if you're deleting back seats. Vertical baffle is going to simplify how the sound waves reflect around the cabin. Centrally located subwoofers are also generally poor performers in home or car. Everything behind the subs should ideally be thoroughly sealed off and rigid for best results (like a proper flat wall).

I really can't tell what's going on in that car from the pics, but from what I can tell this would probably look cool and be easy to hide but won't be all that great as far as ease of getting good output or response.

 

[JW266]

The wall behind the subs is very rigid and also is 95% sealed. The area under the enclosure where the seat should be is also super rigid and sealed. The enclosure is a tight fit and when finished there will be no kind of flexing, moving, or leaking into the trunk.

 

[JW266]

Also I will make panel that covers the rear wall from the enclosure up to the rear window. Also a little shelf thing in between the subs that'll hold my kids backpack.

 

[JW266]

Flat wall is generally optimum if you're deleting back seats. Vertical baffle is going to simplify how the sound waves reflect around the cabin. Centrally located subwoofers are also generally poor performers in home or car. Everything behind the subs should ideally be thoroughly sealed off and rigid for best results (like a proper flat wall).

I really can't tell what's going on in that car from the pics, but from what I can tell this would probably look cool and be easy to hide but won't be all that great as far as ease of getting good output or response.

Also what do you mean by "centrally located?" This 3 way active setup. Tweets in the sail panels, mids in the doors, subs in the back seat.

 

[hispls 5,000+ posts]

Also what do you mean by "centrally located?"

I mean the baffle where the subs are mounted being 2-3 feet in front of the rear wall. This sort of thing invites troubles with standing waves as the wave coming from the subs isn't just going up to the front and reflecting back to where the subs are but there's a wave going front then reflecting back to where the subs are (and also to the rear of the vehicle) and another wave going to the rear then reflecting back to the front and then back. If you've ever played with a wave pool in physics class you might have a clearer picture of what I'm trying to say here but you could possibly replicate this with just a baking pan filled with water and just wiggling your finger. Try it in the corner and see how the waves propagate and then start bouncing back and interfering with each other, then try again further and further away from the corner towards the center and see how messy the waveform in the pool starts to look.

Not saying that you can't get OK results doing what you suggest, but even just doing a trunk-wall should give superior results though depending on the shape of the opening this is often impractical. The point being anything besides a flat wall is going to be sub-optimum so just understand you're making a compromise here and may end up with some odd peaks and nuls in your response curve.

 

[JW266]

I mean the baffle where the subs are mounted being 2-3 feet in front of the rear wall. This sort of thing invites troubles with standing waves as the wave coming from the subs isn't just going up to the front and reflecting back to where the subs are but there's a wave going front then reflecting back to where the subs are (and also to the rear of the vehicle) and another wave going to the rear then reflecting back to the front and then back. If you've ever played with a wave pool in physics class you might have a clearer picture of what I'm trying to say here but you could possibly replicate this with just a baking pan filled with water and just wiggling your finger. Try it in the corner and see how the waves propagate and then start bouncing back and interfering with each other, then try again further and further away from the corner towards the center and see how messy the waveform in the pool starts to look.

Not saying that you can't get OK results doing what you suggest, but even just doing a trunk-wall should give superior results though depending on the shape of the opening this is often impractical. The point being anything besides a flat wall is going to be sub-optimum so just understand you're making a compromise here and may end up with some odd peaks and nuls in your response curve.

Aahh.. I see what you're saying. Well I wasn't willing to cut into the back wall and having the subs facing full forward would inhibit seat movement. Pretty sure the only reason they put rear seat in it was so they could call it a 4 seater for insurance reasons.

I glassed it and didn't think I would have this much airspace.. I've got enough that I could add ports to it. But which way would I aim the ports? Aren't they supposed to be like 90* from the sub facing?

 

[hispls 5,000+ posts]

Aahh.. I see what you're saying. Well I wasn't willing to cut into the back wall and having the subs facing full forward would inhibit seat movement. Pretty sure the only reason they put rear seat in it was so they could call it a 4 seater for insurance reasons.

I glassed it and didn't think I would have this much airspace.. I've got enough that I could add ports to it. But which way would I aim the ports? Aren't they supposed to be like 90* from the sub facing?

The issue is you have a wave originating not at the rear wall, reflecting off the rear wall and meeting the wave that's already heading forward some bit out of phase. Box all the way to the rear (or in a rear corner) regardless of which direction subs/port face is going to be more reliable and generally better.

As far as where to fire the port, the important bit is really just to keep the opening far enough away from anything else that nothing else is effecting the effective volume or opening area. Generally a port width away from hard walls in the car and the woofer itself is considered adequate.

From there I'd suggest that having sub and port on the same face and pointing the same direction is likely the safest bet but you just won't know until you test and depending on the dimensions of the box, sub, and port required some combinations will be physically impossible. I've had good luck with almost every variation of subs facing up, back, or front and ports going out the same side, a different side, or out the side of the box... depending on the vehicle. For what it's worth the difference between any of those variables usually isn't that dramatic and you really can't predict this so if you're really hung up on optimizing this your only hope is to come up with a good plan on how to be able to modify the box several times to test every variation.

 

[JW266]

The issue is you have a wave originating not at the rear wall, reflecting off the rear wall and meeting the wave that's already heading forward some bit out of phase. Box all the way to the rear (or in a rear corner) regardless of which direction subs/port face is going to be more reliable and generally better.

As far as where to fire the port, the important bit is really just to keep the opening far enough away from anything else that nothing else is effecting the effective volume or opening area. Generally a port width away from hard walls in the car and the woofer itself is considered adequate.

From there I'd suggest that having sub and port on the same face and pointing the same direction is likely the safest bet but you just won't know until you test and depending on the dimensions of the box, sub, and port required some combinations will be physically impossible. I've had good luck with almost every variation of subs facing up, back, or front and ports going out the same side, a different side, or out the side of the box... depending on the vehicle. For what it's worth the difference between any of those variables usually isn't that dramatic and you really can't predict this so if you're really hung up on optimizing this your only hope is to come up with a good plan on how to be able to modify the box several times to test every variation.

Firing the port the same directions as the woofer would be the easiest. And my eyeball says there is enough depth that the 10ish inches of port on each side could be fully internal.

Now after I threw everything together last night the output is a whole lot more than I expected to gain going from 1 12 to 2 12. For whatever reason I spaced the impedemce difference lolol. Single 12 was a d2. Running off a 2 channel Amp with each coil wired to a channel. New (old) subs are d1.55 wired to same Amp so like 0.74 on each channel. Not sure I need to worry about ports now. Gotta do some tuning. It's a thing for me. Too many concussions mixed with too many metal shows mixed with too many drugs mixed with too much stress means my ears can be difficult.

Not really trippin on having a supremely optimized setup. Just need the death metal to say tight and not get all muddy and gross on lower levels. But then also for fun be able to crank the knob and drop the panties.

 

[JW266]

 

[hispls 5,000+ posts]

View attachment 36092

That looks good, and this picture is a bit better for me to get where these are in the vehicle (what kind of cabin you have).

If they share airspace you could probably use a 6" round port in the center, if it has to come out a bit it'll still be right about the same plane as the subs and center is a safe bet to keep both subs pressurizing equally. That said, if that cabin is as small as it looks you probably won't need much more to do well in there.

My only concern out of all of this is what amp will safely drive .7 ohm per side?

 

[JW266]

That looks good, and this picture is a bit better for me to get where these are in the vehicle (what kind of cabin you have).

If they share airspace you could probably use a 6" round port in the center, if it has to come out a bit it'll still be right about the same plane as the subs and center is a safe bet to keep both subs pressurizing equally. That said, if that cabin is as small as it looks you probably won't need much more to do well in there.

My only concern out of all of this is what amp will safely drive .7 ohm per side?

PA4002 from like 1999. Still haven't given it all the juice yet. But ran it well above normal listening levels for awhile and even being hidden under the floor in the trunk where air flow can't be good it ain't even get warm. I need to learn all about how to put a dummy load on the amp to set the gain with a dmm. Have it set now for 500 @ 2ohm without subs hooked up.

 

[JW266]

If they share airspace you could probably use a 6" round port in the center, if it has to come out a bit it'll still be right about the same plane as the subs and center is a safe bet to keep both subs pressurizing equally.

Documentation says for port to be 4" Dia by 10" length per sub.
Wouldn't it need to be an 8" x 10" for 2 subs? Or 2 - 4"x10" or math with circles ***** some serious ass.

 

[hispls 5,000+ posts]

Documentation says for port to be 4" Dia by 10" length per sub.
Wouldn't it need to be an 8" x 10" for 2 subs? Or 2 - 4"x10" or math with circles ***** some serious ***.

It may be worse than 'math with circles' I'm afraid. The math to tune a port isn't exactly double everything and it'll land at the same tuning. You'll need to figure out what tuning is recommended then chose a new box volume, chose a new port area, then run that into some box design software to see what port length will get you where you wanted to be.

 

[JW266]

It may be worse than 'math with circles' I'm afraid. The math to tune a port isn't exactly double everything and it'll land at the same tuning. You'll need to figure out what tuning is recommended then chose a new box volume, chose a new port area, then run that into some box design software to see what port length will get you where you wanted to be.

That's what I had figured. Messing with it any further will most likely just make things worse. And then these subs are pretty old. They're solid now and were unused when I acquired them and kept in decent storage conditions. But I'm not expecting them to last forever.

After getting TA dialed in and some more playing they're plenty loud enough for me lol. I am super surprised with how hard this system goes. I was expecting this amp to melt by now but after long drives at levels way above my normal it gets about the same temp as the c5d I have running mids and highs. I been sleeping on this amp for years lol.

I think I know what you meant about it being peaky tho. It is rare but there are certain notes in certain hip hop songs somewhere around 80hz that will jump out as just way over the top. Haven't heard it from any musical instruments just like the computer bass notes that are used today I can move the xover and it'll go away but everything else I listen to sounds great with just small adjustments on the knob. Changing eq settings and xovers is annoying to be constaly changing.