I scavenged a piece of PVC pipe 7.5 inched inner diameter and two feet long. Massive, and expensive if i were to buy it myself. so i am stoked, imagind how kick *** a sub port you would put your head into would be.
Is it useable at all?
what kind of monster specs would my driver need?
thanks
Is it useable at all?
what kind of monster specs would my driver need?
thanks
Increasing port diameter is usually done to reduce port noise. Unless you are moving a LOT of air at VERY low frequencies, this will be a pretty nifty enclosure for a small sub, but not a good port for a mid-size sub.
When I say a LOT of air, I am thinking rock-concert loud. Or louder.
When I say a LOT of air, I am thinking rock-concert loud. Or louder.
It's definitely useable
Be warned, large PVC ports have a seductive nature that can sneak up on you....
You will find that a large dia pipe needs a large box. Here are some figures (sorry about the metric..)
for a port 187.5mm dia and 600mm long:
a tuning frequency of 35hz requires a box size of 111 litres
a tuning frequency of 27hz requires a box size of 154 litres
a tuning frequency of 20hz requires a box size of 300 litres
pipe resonance 286hz
I have built a dual 10inch sub with a pair of 6inch ports in a 130 litre box tuned to 28hz. With 240w applied, this runs with a peak airspeed of a very conservative 8 metres/sec.
A single 7.5 inch port would have run at around 11 m/sec (although it would have needed to be about 1060mm long)
If you flare both ends, I would guess that you could run up to a pair of twelves with about 300w total.
Look for drivers with an Xmax of around 10mm, which will be happy in about 80-150litres each.
regards
Collo
Be warned, large PVC ports have a seductive nature that can sneak up on you....
You will find that a large dia pipe needs a large box. Here are some figures (sorry about the metric..)
for a port 187.5mm dia and 600mm long:
a tuning frequency of 35hz requires a box size of 111 litres
a tuning frequency of 27hz requires a box size of 154 litres
a tuning frequency of 20hz requires a box size of 300 litres
pipe resonance 286hz
I have built a dual 10inch sub with a pair of 6inch ports in a 130 litre box tuned to 28hz. With 240w applied, this runs with a peak airspeed of a very conservative 8 metres/sec.
A single 7.5 inch port would have run at around 11 m/sec (although it would have needed to be about 1060mm long)
If you flare both ends, I would guess that you could run up to a pair of twelves with about 300w total.
Look for drivers with an Xmax of around 10mm, which will be happy in about 80-150litres each.
regards
Collo
tade said:i was biking around town again tonight...
scored a piece with an ID of twelve inches and three feet in length. i think this may be obsessive...
Your nicking from building sites aren't you?
Theiving pikey
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