dominikz
Addicted to Fun and Learning
- Joined
- Oct 10, 2020
- Messages
- 876
- Likes
- 2,813
The question in the title relates to quasi-anechoic loudspeaker measurements where we do a gated far-field HF measurement, and splice it with nearfield LF measurements of woofers and ports. I've mentioned this already in another thread, but thought it's maybe better suited to a dedicated discussion.
To build the loudspeaker LF response we first need to scale measured frequency responses based on the ratio of effective radiating surfaces or each radiating element (be it a woofer or a port).
This is actually where my question ties in. If the port is a simple cylinder, it is easy to calculate the radiating area. However, often "flared" ports are used, and sometimes the difference in diameter between extremes of the flare can be quite large - e.g. on Revel M16 the narrow part of the port ("throat") is 4,5cm in diameter whereas the widest part of the port ("mouth") is 7,5cm in diameter.
So my question is which port diameter do we use as an 'effective' radiating diameter: port 'throat', 'mouth' or something in between?
The measurements I did so far seem to show fairly good agreement with existing measurements if I use the port 'mouth' diameter when calculating the port radiating surface, but my sample size is extremely small (two speakers so far) and I would love to see some references and/or guidelines for this.
Hope some of you with more experience can provide guidance to this loudspeaker-measuring rookie
Thanks!
To build the loudspeaker LF response we first need to scale measured frequency responses based on the ratio of effective radiating surfaces or each radiating element (be it a woofer or a port).
This is actually where my question ties in. If the port is a simple cylinder, it is easy to calculate the radiating area. However, often "flared" ports are used, and sometimes the difference in diameter between extremes of the flare can be quite large - e.g. on Revel M16 the narrow part of the port ("throat") is 4,5cm in diameter whereas the widest part of the port ("mouth") is 7,5cm in diameter.
So my question is which port diameter do we use as an 'effective' radiating diameter: port 'throat', 'mouth' or something in between?
The measurements I did so far seem to show fairly good agreement with existing measurements if I use the port 'mouth' diameter when calculating the port radiating surface, but my sample size is extremely small (two speakers so far) and I would love to see some references and/or guidelines for this.
Hope some of you with more experience can provide guidance to this loudspeaker-measuring rookie