Home Forums DIY Speakers and Subwoofers Anyone familiar with the C-note bookshelf speaker kit? Reply To: RE: Anyone familiar with the C-note bookshelf speaker kit?

  • kanaaudio

    September 19, 2020 at 8:13 pm


    Thank you for that, once again. I understand the first part fine, that makes total sense to me.

    But you lost me on this second part:
    “But where you place the port on the enclosure determines the phase shift the port needs to accomplish in order to have the port energy match the front face energy to actually reinforce each other. So, if the port is on the front, you want it to be in phase at the resonant frequency so they both push and pull in sync (technically the port is 180° since the back of the cone is pulling while the port is pushing). When you rear port, you want the rear port to be 180° (and again, technically this is 0° since the port is tracking the back of the cone) so that by the time it wraps around the speaker it becomes in phase with the front. The tuning of the port / length determines the output phase of the tuned frequency.”

    I am sure you have actually answered my question, I just don’t understand the answer 🙂 For example, if I place a port on the rear, say 1,375″ diameter and 4″ in length as per your calculation, that would be optimal for that given setup. What would be different if I placed the port on the front in stead? A 180 degree bending tube, a different length? A different calculation?

    I will be trying to install a port on the back of the speaker box. Are the calculations you have given me suitable for that? Do I need to take something additional into account, since you wrote that the reason PE had chosen a 7″ length for the port, even though the calculations states 4″, might be because of phase inversion due to rear porting?

    Sorry I keep pushing on this, I just really want to understand. I might be talking about something totally different 🙂

    – Martin