Here's my angle-
It's a midrange. Can you port it? Yes.
Do you need to port it? If you are xovering low enough where the response comes into play, then- maybe.
What happens? The port takes over when the midrange approaches tuning frequency, and then the driver moves less and the port moves more air than above this point. The driver is the main midrange producer down to this point.
How is the driver response? If you xover below the port tuning, it can be higher than 4th order rolloff depending on the 4th order vented rolloff plus the additional highpass slope. If you xover above the rolloff, then you might get a slower rolloff until tuning. You can xover high enough to avoid the change in box rolloff if needed.
Would I do it? No. Sealed midranges are allowing for more options and better blending with the woofer involved on a shallower rolloff.
What would I do instead? Make the mid chamber as large as physically possible to not impart the enclosure sound or damping on the midrange diaphragm. IE- let it do what it does best, naturally aspirated.
Later,
Wolf
It's a midrange. Can you port it? Yes.
Do you need to port it? If you are xovering low enough where the response comes into play, then- maybe.
What happens? The port takes over when the midrange approaches tuning frequency, and then the driver moves less and the port moves more air than above this point. The driver is the main midrange producer down to this point.
How is the driver response? If you xover below the port tuning, it can be higher than 4th order rolloff depending on the 4th order vented rolloff plus the additional highpass slope. If you xover above the rolloff, then you might get a slower rolloff until tuning. You can xover high enough to avoid the change in box rolloff if needed.
Would I do it? No. Sealed midranges are allowing for more options and better blending with the woofer involved on a shallower rolloff.
What would I do instead? Make the mid chamber as large as physically possible to not impart the enclosure sound or damping on the midrange diaphragm. IE- let it do what it does best, naturally aspirated.
Later,
Wolf
No sir ... not at all. I DO NOT have time in my life, at this time, for reading a book and studying. I want to learn it all. But until I have more time I can dedicate to it, I have only this way of learning on the go, for now.
Hey Wolf ... You have been answering questions I have asked, for probably 10 years or more. I can't thank you enough for the above words. This is ALL I needed to fully understand, about how porting affects a midrange. This info allows me to dig deeper, for an even greater understanding of it. But the basics you covered about how a midrange port is utilized, cleared up everything. Thanks again.
Thanks again, for taking the time.
I assume the box sound comes from resonances.
After studying my three way studio monitors and making a few calculations in my latest designs I took the opposite approach. I go with the smallest enclosure possible behind a driver with the goal of getting the first resonant mode of the cavity above the operating range of the driver. I used software called boxnotes to calculate the cavity frequencies. I also used Finite Element Models to ensure the panel resonances were above the operating frequency range of the drivers. This all based on the assumption that the sound imparted by a box comes from resonances of the box.
Of course in the limit for large box is the open baffle, where you only have the panel resonance to deal with.
My two cents.
The 1st vented midrange ever was in the Electro Voice Interface D. It was a very good speaker for its time.
Let's talk about the design of the Electrovoice Interface D speakers -
Techtalk Speaker Building, Audio, Video Discussion Forum
Let's talk about the design of the Electrovoice Interface D speakers -
Techtalk Speaker Building, Audio, Video Discussion Forum