Ported Doors
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500 Watt CAFz'r
Joined: Oct 2004
Posts: 870
There were lots of steps to complete the Cav’s ported door enclosures.
First I had to find out if was feasible, and if it was worth the extra effort.
I posted on several car audio boards to see if anyone had experience with ported doors…most replies came back “a waste of time”, but one person had done them and convinced me to try it.
To properly port a speaker box, calculations must be done using the Theile/Small specs….unfortunately, there are no specs published for most door speakers, so I had to measure them myself. First I set up the test equipment, built a small test enclosre, and got the info I needed. That took the better part of a day, until I was sure I had the proper numbers.
Using air filled bags, I made a rough estimate of the cubic inches I’d be able to get on the door, while still retaining some ergonomics
Then I ran the specs through several programs, to get the optimum box and port sizes, with the available space on the door. The results were very promising…over 6dB gain at 60 Hz, compared to regular sealed, or infinite baffle panels.
All this research took approximately a week or so, but I now had a plan!
To begin the install, we first installed the power window, and lock motors in the shaved doors.
Next, a layer of carpet (to allow a bit of clearance) , a layer of foil, coated with release agent, and several layers of ‘glass and resin were applied to the door.
The glass was allowed to cure overnight, then using the stock panel as a guide, the excess glass was trimmed with a grinder, leaving the “back” side of the enclosure.
The OEM door panel was then screwed to the door, and liberally coated with release agent. Then I laid glass and resin onto the outside edges to form a mould. Another day to cure the mould, then it was polished and painted on the inside, then screwed to the door again, along with the back panel.
Glass was laid up on the inside of the mould, and to the back, forming three more sides of the box.
The mould was pried away, leaving an exact copy of the OEM panel edge, including the attachment insets.
To form the ports, I made a mould out of hard, flexible plastic, curved to fit the box. After the glass hardended over the mould, the plastic was peeled out, leaving a nice shiny surface inside.
The top half of the stock panel was then attached to the door, and glass laid from the back panel to the edge of the stock panel, forming the 5th side of the box. Studs were glassed into the new panel, to create a way of joining the two parts together from behind, so no screws could be seen.
Two sets of MDF rings were made for each speaker…one for a mounting baffle, and another to sink the grill flush.They were glued together, and fastened to the 5 sided box with fibreglass, along with the ports. The ends of the ports were built up quite a bit, to allow for flaring.
The recessed area above the speakers had to be constructed to allow the panels to clear the dash, so a curved panel of glass was placed to give me a point to stretch the grill cloth.
Once everything was in place, and a test install done to check for clearances, the grill cloth was stretched over the box and coated with resin to form the front shape….then 5 layers of resin and mat were applied for strength, then a layer of reinforced filler to even the shape.
[ July 22, 2005, 07:47 PM: Message edited by: Car Trek ]
First I had to find out if was feasible, and if it was worth the extra effort.
I posted on several car audio boards to see if anyone had experience with ported doors…most replies came back “a waste of time”, but one person had done them and convinced me to try it.
To properly port a speaker box, calculations must be done using the Theile/Small specs….unfortunately, there are no specs published for most door speakers, so I had to measure them myself. First I set up the test equipment, built a small test enclosre, and got the info I needed. That took the better part of a day, until I was sure I had the proper numbers.
Using air filled bags, I made a rough estimate of the cubic inches I’d be able to get on the door, while still retaining some ergonomics
Then I ran the specs through several programs, to get the optimum box and port sizes, with the available space on the door. The results were very promising…over 6dB gain at 60 Hz, compared to regular sealed, or infinite baffle panels.
All this research took approximately a week or so, but I now had a plan!
To begin the install, we first installed the power window, and lock motors in the shaved doors.
Next, a layer of carpet (to allow a bit of clearance) , a layer of foil, coated with release agent, and several layers of ‘glass and resin were applied to the door.
The glass was allowed to cure overnight, then using the stock panel as a guide, the excess glass was trimmed with a grinder, leaving the “back” side of the enclosure.
The OEM door panel was then screwed to the door, and liberally coated with release agent. Then I laid glass and resin onto the outside edges to form a mould. Another day to cure the mould, then it was polished and painted on the inside, then screwed to the door again, along with the back panel.
Glass was laid up on the inside of the mould, and to the back, forming three more sides of the box.
The mould was pried away, leaving an exact copy of the OEM panel edge, including the attachment insets.
To form the ports, I made a mould out of hard, flexible plastic, curved to fit the box. After the glass hardended over the mould, the plastic was peeled out, leaving a nice shiny surface inside.
The top half of the stock panel was then attached to the door, and glass laid from the back panel to the edge of the stock panel, forming the 5th side of the box. Studs were glassed into the new panel, to create a way of joining the two parts together from behind, so no screws could be seen.
Two sets of MDF rings were made for each speaker…one for a mounting baffle, and another to sink the grill flush.They were glued together, and fastened to the 5 sided box with fibreglass, along with the ports. The ends of the ports were built up quite a bit, to allow for flaring.
The recessed area above the speakers had to be constructed to allow the panels to clear the dash, so a curved panel of glass was placed to give me a point to stretch the grill cloth.
Once everything was in place, and a test install done to check for clearances, the grill cloth was stretched over the box and coated with resin to form the front shape….then 5 layers of resin and mat were applied for strength, then a layer of reinforced filler to even the shape.
[ July 22, 2005, 07:47 PM: Message edited by: Car Trek ]
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