Bass in a ragtop?

[sinister-kustoms]

I'm about to start on an install for a '66 Pontiac Catalina ragtop. What would be the best way to get the bass to travel to the cabin area?
The main problem is when the top is down as it fills the compartment between the trunk and rear seat.
Does anyone have any advice on 'venting' into the cabin? I was thinking of mabey doing a forward facing box firing into a 'tunnel' that runs under the top when it's down. Will it actually help the bass travel?
Or am I best to just do a rear facing box into the trunk?

[sqoverspl]

I drove an 2000 mustang convertable as my first car that my step dad let me use and if you want bass it should be ported. With a ported box it would hit it with the top down. You also need to face it toward the back to get the most output.

[Aaron'z 2.5RS/WRX]

Originally Posted by sinister-kustoms

I'm about to start on an install for a '66 Pontiac Catalina ragtop. What would be the best way to get the bass to travel to the cabin area?
The main problem is when the top is down as it fills the compartment between the trunk and rear seat.
Does anyone have any advice on 'venting' into the cabin? I was thinking of mabey doing a forward facing box firing into a 'tunnel' that runs under the top when it's down. Will it actually help the bass travel?
Or am I best to just do a rear facing box into the trunk?

You got any pics we could use to visualize?

[Austin]

Originally Posted by sqoverspl

I drove an 2000 mustang convertable as my first car that my step dad let me use and if you want bass it should be ported. With a ported box it would hit it with the top down. You also need to face it toward the back to get the most output.

X2

In my sister 04 mustang vert it has a smallllll trunk so i could only do a single 12 sealed and it sounded decent even with the top down. The sub was firing upward too due to size restrictions. If you have the trunk space ported would be the way to go though as sqoverspl said.

[sinister-kustoms]

Here's a few pics if it helps.
Ragtop storage area. I think there's around 4-5" between the floor and the top when it's down.


Looking in from the trunk

I'm aiming for SQ over SPL, so it will be a sealed box. I just want to achieve maximum sound whether the top is up or down. The owned isn't a hardcore audio guy, it took some selling to get this much, so a nice clean sound is the goal. Notihng too boomy.

[Aaron'z 2.5RS/WRX]

Hmm wow... How about a center console mounted 8".... lol... Or maybe glove-box mounted.. lol..

Even with 4" under the top when it's down, you'll have an excessively long port to try and port all the way forward.. IMO

Is the back seat useful?

Is the guy going all original or are you doing some custom bits? If you get to play, I'd say center console..

[GregU]

Originally Posted by Aaron'z 2.5RS/WRX

Hmm wow... How about a center console mounted 8".... lol... Or maybe glove-box mounted.. lol..

Even with 4" under the top when it's down, you'll have an excessively long port to try and port all the way forward.. IMO

Is the back seat useful?

Is the guy going all original or are you doing some custom bits? If you get to play, I'd say center console..

x2 on the center console. Or how about making the back seats into bucket seats and have something like a 8w7 in between the two? A buddy of mine did this in an old camaro and it sounded VERY nice. Of course he also did about $22,000 in fiberglass and upholstery work to the interior.

[sinister-kustoms]

Sorry, I should have mentioned the gear. I've got one kicker 10" L5.
There's not really the room for a console with the front bench. The guy has a big family also, so all the seating is needed. The glovebox is no-go, we've still got to cram A/C and the air ride computer under the dash.
Would a sealed box firing into a vent (say 55-60" by 4-5") really affect the tuning like a port would though?

[mokedaddy]

You may want more than a single 10 to get some good sound into the cabin. Here are a few pics of the 70 cutlass I did this winter. You can hear it clear as day at 70 going down the road.

I guess I dont have any finished pics on this computer but you will get the idea.




These are sealed, and did quite a bit of testing. Almost did four 8s ported but this worked out better.

[mokedaddy]

I will have to look around for pics of the box. The trunk in the cutlass rises just like the catalina trunk does. It is an odd shape but is almost four cubes gross and fits in the trunk almost perfectly.

[sinister-kustoms]

Looks sweet! So that's just a plain sealed box firing into the trunk? It's a ragtop Cutlass yea?
I'd love to add more gear, but selling a NZD$3500 stereo plus a custom install to a non-audio guy was hard enough as it was. I'd be pushing shit uphill trying to add $1500 to that for another sub & amp.

[mokedaddy]

Originally Posted by sinister-kustoms

Looks sweet! So that's just a plain sealed box firing into the trunk? It's a ragtop Cutlass yea?
I'd love to add more gear, but selling a NZD$3500 stereo plus a custom install to a non-audio guy was hard enough as it was. I'd be pushing shit uphill trying to add $1500 to that for another sub & amp.

Yeah I am sure the equipment is considerably cheaper here for the most part. I have right around $1000 in equipment but did the install and restoration mostly by myself. It is a sealed box but it is definitely not your standard 6 sided box. The cover for the top sits on top of the box while the top of the box sits in between the trunk arms and the bottom angles up.

Here are a few pics of the car.




If nothing else it may give you a few ideas to kick around.

[Patrick Bateman]

That's a big ol' trunk... Shouldn't you just put the sub in there?

A 50hz soundwave is 686cm long... Getting the bass into the front of the cabin will NOT be a problem. All your worrying about venting the output of the sub into the cabin is a waste of time.

At these frequencies, the sheet metal is all but invisible.

[chad]

Originally Posted by Patrick Bateman

ime.

At these frequencies, the sheet metal is all but invisible.

I would almost have to disagree with that.

[60ndown]

lots of cone area + big power = no problems. (1x15" + 1500 wrms)

small cone area + medium power = no bass. (1x10 + 350 wrms)

[mokedaddy]

Originally Posted by Patrick Bateman

That's a big ol' trunk... Shouldn't you just put the sub in there?

A 50hz soundwave is 686cm long... Getting the bass into the front of the cabin will NOT be a problem. All your worrying about venting the output of the sub into the cabin is a waste of time.

At these frequencies, the sheet metal is all but invisible.

The problem I had was more about getting loud enough to be heard over wind noise at 75mph.

I also have a good friend with a bmw that has a completely sealed off trunk that would highly disagree with the sheet metal being invisible.

[Patrick Bateman]

Originally Posted by mokedaddy

The problem I had was more about getting loud enough to be heard over wind noise at 75mph.

Big time, that's definitely the challenge in a convertible. There's no real cabin gain to speak of. At 40hz, the average car is picking up about 15db of cabin gain. So if you can hit 110db in a sedan with 100 watts, you'd need FIVE THOUSAND watts to hit 110db in a convertible with the same sub.

The other poster, who put a sub box in with four subs, is on the right track. To get any kind of bass will require a lot of power and a lot of excursion.

Originally Posted by mokedaddy

I also have a good friend with a bmw that has a completely sealed off trunk that would highly disagree with the sheet metal being invisible.

I've measured subs in the cabin and in the trunk, and below 100hz, the response was virtually identical. There's a dip and a peak here and there, but nothing substantial.

Was your friends opinion based on listening or measurements? Due to the Fletcher Munson curves, a small reduction in low frequency output may be perceived as a big reduction in output, since our sensitivity to low frequencies is very poor. I'm not trying to discount your friends opinion, just saying that if it's based on listening, it will be colored by how our hearing mechanism operates. There are a lot of good reasons to seal off a trunk. I've wanted a wagon for years, and the fact that they're a hatchback makes them a p.i.t.a. for a good stereo.

In addition, our sensitivity to high frequencies is very good. Sealing the trunk *will* make a big difference in the range above 100hz, and the harmonics from the subwoofer are often perceived as "bass."

It's those harmonics that drag the image to the back of the car though, which is why I don't want them in my sub.

[mokedaddy]

It wa me that built the car with the four subs. I knew that was what was needed to get the sound i was looking for.

As for my friend, the trunk is completely sealed off though. No speaker holes, no ski pass, nothing letting air out. I doubt he used any measuring equipment but it is real quiet for what it should be. Even to the point that is almost hard to hear anything at highway speeds. The sub is actually enclosed within the trunk so to speak. There is nothing which lets the wave through.

I understand what you mean with hearing being far from perfect. I am also not disagreeing with you at all or your scientific findings which you have wealth of. I have even learned a great deal from you, but a few holes were cut in the sheet metal and at the very least it appears louder. If it is only perception that makes the customer happier...then that is good enough for me.