Here are the port dimensions I would choose: 55,87 x 4 x 58 cm (width x height x length). A slightly smaller alternative with 4 m/s more port air velocity would be the following: 55,87 x 3,5 x 50 cm (width x height x length).
21 - 40 of 81 Posts
I'm not aware of exact calculations only of rough tendencies. See my earlier explanations (I highlighted some clauses for you):
This was it about the relation between chassis and port position. Now the more important factors of the actual position of chassis and port in your listening room:On the contrary the port positioning [in relation to the chassis] does make a minor difference. It's not like one position would mess up the entire performance but what it does is in fact influencing the port efficiency above your tuning frequency. As you probably know the sound radiation is 180 degrees in phase on the other side and thus would normally cause an almost complete sound cancellation in front of the chassis. Therefore one enclosure's purpose is either turning phase optimally to 360 or 0 degrees in order to use the back sound or destroying it (sealed box concept). Having said this one can conclude that with rising distance between chassis and port also the sound addition rises above the tuning frequency as their radiated sound waves are more in phase whereas the output around the tuning frequency stays the same because here the port resonance (delayed) already achieve this phase turn. According to measurements this turns out true but in nearly all cases compared with the tuning frequency's wavelength the enclosure's dimensions are so small that the impact here is relatively neglectable. With large floorstanding speakers the max possible port distance will give you a few extra db but not much.
Long story short - Choose it to your (visual) liking...
Placing the acoustic source closer to walls will achieve more alignment between direct sound and reflections (not aligned phases would cause the mentioned interferences and thus sound cancellations).
I think it can be generally said that facing your chassis against walls could (but not necessarily) result in "washed out" upper bass. Therefore in order to reach more clean and direct upper bass the chassis should better face the open room optimally your listening position.
To sum things up the compromise I would make (as audio will always be a compromise) is to place the chassis on the enclosure's front facing your listening position and the port on the enclosure's lower back facing the near room's backwall.
I hope this answers your questions...
Here it is, only held together w two clamps at the far side.
Nice to see those proceedings.
This will result in a slightly higher tuning frequency, but assuredly nothing to worry about.
Great! Thanks!
Here is my progress so far. The center brace isnt in its final position; its just spacing the sides out during glue & screw install.
![Product Plywood Wood Handrail Stairs]()
Here is my progress so far. The center brace isnt in its final position; its just spacing the sides out during glue & screw install.
1st coat of primer
Need to put a coat of paint on top, sand it all down, toss another coat on via backroll, and then its time for the fun to begin!
Letting this dry, then the polyurethane goes on.
Old vs new.
Just waiting on the mounting bolts for the woofer now...
All done. Only played a test tone sweep from 125Hz down to 20, and it rattled the sheetrock.
The dayton amp has a ground loop hum, so I will fix that.
Also, the overall volume even at max gain isn't as loud as I would have expected. Certainly plays lower, but not louder than my old Vega. Guess I need more watts ?
21 - 40 of 81 Posts
