Originally Posted by
fatmarley
It's well worth experimenting, but it's very difficult to know what's going on without modelling and measuring, as well as listening.
Here's a graph showing the Monitor Gold 15 in a 172ltr ported enclosure. The grey line is with 3 ports 3" diameter x 5" long, the black line is with 2 ports. As you can see you lose a bit in the all important 60hz to 100hz region when you block a port.
Here's the 172ltr enclosure again with the 3 ports (grey line again), The Black line is 116ltr but with only two ports (if you don't block a port the peak just moves up in frequency). You still have the all important 60hz to 200hz but that nasty peak at 40hz is gone.
I can also model aperiodic, but It's only really any good for a high Q driver in a sealed enclosure that needs the bass peak reducing.
Thanks, that's very interesting. My cabinets are 255 ltrs (net) minus the cones/cage, braces ports. The three ports are 4 inches in diameter and 10.5 inches long. According to my calculations, that's tuned to 29 Hz. However what confusions the Aperiodic shelf has caused is unknown to me until I experiment further. Apparently Aperiodic enclosures can't be ported and tuned. They just need a large shallow vent. I sadly have no measuring equipment.
Denzil
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