Ported Doors
07-22-2005, 03:00 PM
#1
500 Watt CAFz'r
Thread Starter
Join Date: Oct 2004
Posts: 870
Did an article on the door enclosures, so I thought I'd give you guys first crack at it. After all, it started on this forum. Comments and feedback welcome.
__________________________________________________
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.
More to come next post
[ July 22, 2005, 04:15 PM: Message edited by: Car Trek ]
__________________________________________________
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.
More to come next post
[ July 22, 2005, 04:15 PM: Message edited by: Car Trek ]
07-22-2005, 03:18 PM
#2
500 Watt CAFz'r
Thread Starter
Join Date: Oct 2004
Posts: 870
Now all that remained was the final finish, with a few minor fitment adjustments. Progressively finer body fillers were used, with 2 part putty up to 280 grit, then high build primer up to 400 grit.
To paint the pieces, first 2 coats of black base were applied, folowed by a coat of clear containing a small amount of House of Kolor Prism flakes. This coat, with the flakes a few millimeters apart, gives the panels the “stars”.
Four coats of clear were then applied to bury the flakes. The painting process took 8 hours in the booth, from the first coat to the last, and another couple of hours babysitting them, as the extra thick paint wanted to sag a bit, so some careful rotation of the pieces was required to prevent runs or sags.
Even with 4 coats of clear, there were a few spots where the huge flakes were bumpy, so a wet sand with 800, and 1000 grit, followed by a careful buff job brought the finish up.
[ July 22, 2005, 04:22 PM: Message edited by: Car Trek ]
To paint the pieces, first 2 coats of black base were applied, folowed by a coat of clear containing a small amount of House of Kolor Prism flakes. This coat, with the flakes a few millimeters apart, gives the panels the “stars”.
Four coats of clear were then applied to bury the flakes. The painting process took 8 hours in the booth, from the first coat to the last, and another couple of hours babysitting them, as the extra thick paint wanted to sag a bit, so some careful rotation of the pieces was required to prevent runs or sags.
Even with 4 coats of clear, there were a few spots where the huge flakes were bumpy, so a wet sand with 800, and 1000 grit, followed by a careful buff job brought the finish up.
[ July 22, 2005, 04:22 PM: Message edited by: Car Trek ]
07-24-2005, 03:56 PM
#9
500 Watt CAFz'r
Thread Starter
Join Date: Oct 2004
Posts: 870
Doors have Fusion PowerPlant compnents...they sound incredible for the price....about like a pair of tens.
I'd be satisfied with the amount of bass they produce with no subs, but there's a pair of 12's in the trunk to get it really unbearable in there.
With the subs off, and the doors running from 60 Hz up, the mirror moves almost 1/2" when it's cranked up.
We're running a Fusion FP 1402 amp to the doors at 2 ohms.
I don't think it's the nicest SQ system I've done, but man does it hit you in the gonads with the tom toms.
There's not a buzz or rattle anywhere on the doors either, and the outer skin hardly moves at all. The more I play with em, the more I'm likin em.
It's a customer's ride, and after 6 months in the shop, he's been out playin with it, so I haven't had much of a chance to tweak it yet.
The front is all active, thru a Fusion X-over ( the whole car is PowerPlant stuff), and I think a better processor would reveal a lot more capability. I can't seem to get the -3 dB point low enough using this processor, to be able to get the mids up to the point where they are straining.
One thing I will say about the Fusion stuff....3 times now, I've seen clouds of smoke pour out of the tweeters (we have about 100 w/ch available to the two pairs of tweets) but they're still playin.... I'm sure they aren't quite right now, and I'll have to change em eventually, but man thay can take a beating.
The door speakers hardly move at all....the limited excursion of the ported boxes is phenominal....I think I could put a kilowatt to each door with a bit of caution, and the thermal limit would be reached far before the mechanical.
Be fun to see how far they'd go before they melt.
All in all, for 2 sets of $200 comps....pretty impressive. Biggest sounding doors I've heard in my 26 years.
I'd be satisfied with the amount of bass they produce with no subs, but there's a pair of 12's in the trunk to get it really unbearable in there.
With the subs off, and the doors running from 60 Hz up, the mirror moves almost 1/2" when it's cranked up.
We're running a Fusion FP 1402 amp to the doors at 2 ohms.
I don't think it's the nicest SQ system I've done, but man does it hit you in the gonads with the tom toms.
There's not a buzz or rattle anywhere on the doors either, and the outer skin hardly moves at all. The more I play with em, the more I'm likin em.
It's a customer's ride, and after 6 months in the shop, he's been out playin with it, so I haven't had much of a chance to tweak it yet.
The front is all active, thru a Fusion X-over ( the whole car is PowerPlant stuff), and I think a better processor would reveal a lot more capability. I can't seem to get the -3 dB point low enough using this processor, to be able to get the mids up to the point where they are straining.
One thing I will say about the Fusion stuff....3 times now, I've seen clouds of smoke pour out of the tweeters (we have about 100 w/ch available to the two pairs of tweets) but they're still playin.... I'm sure they aren't quite right now, and I'll have to change em eventually, but man thay can take a beating.
The door speakers hardly move at all....the limited excursion of the ported boxes is phenominal....I think I could put a kilowatt to each door with a bit of caution, and the thermal limit would be reached far before the mechanical.
Be fun to see how far they'd go before they melt.
All in all, for 2 sets of $200 comps....pretty impressive. Biggest sounding doors I've heard in my 26 years.
