[Ported Speaker Design] Bass Reflex vs. Slat/Slot

onlyone-jc · Post by **onlyone-jc** » Thu May 04, 2006 5:02 am

Hi.

This is for all you acoustics and speaker design people out there!

There are many studio reference monitors on the market. Some of them carry a round bass-reflex port design in order to vent their cabinets (e.g. Event, Dynaudio), while others carry a slatted or slotted rounded-rectangular port design along the bottom in oder to vent their cabinets (e.g. KRK, Genelec).

- What are the pro's and con's of each design?
- What does one offer that the other doesn't?
- Does vent-position/shape have a dramatic effect on the perceived sound?

Thanks,
onlyone-jc.

Don T · Post by **Don T** » Thu May 04, 2006 7:14 am

Hello:
As I recall, it should make no difference. The design parameters are about size and length. Hmmmmmmm

Round tubes are cheaper and offer less resistance to air flow but then those affects have to be delt with during design and tuning. So, the net difference is 0.

onlyone-jc · Post by **onlyone-jc** » Thu May 04, 2006 8:19 am

So would you say that slotted vents offer more resistance to air-flow?

If so, to me it suggests that this design may give the cabinet a tighter bottom-end in its overall frequency-response. What are your opinions on this idea?

If round vents provide less resistance to air-flow, would this possibley cause an imbalance in the cabinet's overall frequency-response, and thus allow lower frequencies to over-power and slightly dominate the frequency spectrum. Or, would these kind of problems be sorted out in the crossover/amping stage?

Thanks,
onlyone-jc.

AVare · Post by **AVare** » Thu May 04, 2006 8:23 am

Or, would these kind of problems be sorted out in the crossover/amping stage?

Considerations to be addresed in the speaker SYSTEM. No problems, just different pluses and minuses.

Andre

Don T · Post by **Don T** » Thu May 04, 2006 10:49 am

Hello,
Since the port is tuned by virtue of the mass and resonant frequency of the air moving through the port, the difference would be compensated for netting no output difference. The difference between speakers become the physical design. You can get a larger port in a smaller area of the speaker front panel using a rectangular shape. However, this does not lend itself to tweeking the port length if you miscalculate. Rectangular ports are generally part of the cabinet structure. Tubes on the otherhand can be removed, cut or replaced easily making it a favorite among DIYfers.