Mini Scoops - Reality check

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   Yep it is the question, can a port act with both characteristics of Helmholtz resonance and open pipe resonance simultaneously.

The impedance plot of a transmission line gives nothing away, as it also has 2 peaks. To quote Martin J King, "When you combine a pipe and a driver you are merging two mechanical systems to
			produce a new mechanical system with its own resonant properties. You need to look
			at the driver as one system, the pipe as a separate system, and the driver in the
			pipe as an entirely new combined system."

One thing a TL always has is stuffing. Dr Bailey's long haired wool is your friend here. The stuffing helps slow the speed of air, hence lengthening the pipe and filtering out some of the resonances. A mini scoop of course does not have stuffing it its port, so differs here. I wonder what would happen if you stuffed the port. Would lots of people at a dance be covered in long hair ha ha. 

In my BassBox Pro simulations I have the option to add vent resonance peaks. But this doesn't effect the outcome by much because of a few factors. These are 1. The drivers output helps mask the pipe resonances. This would not be the case in a pure bandpass type enclosure. 2. The resonant peaks and associated harmonics are very narrow in bandwidth, making them hard to detect. 3. The system is bandwidth limited. A low pass filter is always used that helps attenuate upper harmonics. 

Granted a larger and longer port does have more problems with resonances, but in my simulations not enough to be problematic, even when not stuffed.

One thing I am sure about is that a mini scoop is not a rear loaded horn. The total lack of the third resonant peak in the impedance plot is enough of a give away here. If a port measurement was to be made of a mini scoop it would not have to be bandwidth limited, as that might mask any of the resonances. 

Maybe the jury is out, but its looking more like a reflex to me. If you look around for mini scoop designs most do seem to have expanding ports. I've seen a few with constant width ports and most of the designs out there appear to have very short ports, maybe around the 1 to 1.2 meter length. The question for those who use these things everyday and have heard many of the different designs is, which goes lower and which plays louder. Does an expanding port sound better than a constant width port. Do longer ports play lower and do smaller throats play lower but with less output. Guess that will go to the grave with them.

Edited by Aman Gebru - 07 January 2017 at 10:28am