Hello friends!
I'm curious to know if there is anything else affecting Group Delay beyond (what I may be clumsily calling) the System Order-Phase relationship?
(I do understand, loosely, that once you take the system out of linear behavior, Group Delay can be strongly affected. I am not looking at that aspect of the conversation right now, unless it is pertinent to understanding how Group Delay works in the more straight forward sense of a properly linear system.)
In a Sealed box, with it's 2nd order roll-off, group delay is not a problem.
In a Ported box with its 4th order roll-off and the introduction of phase due to the ports, Group Delay increases.
In a PR system, 5th order roll-off, Group delay increases more than in a Ported enclosure.
In a Ported box, are there other design consideration that can help decrease the effect of Group Delay in the system? (Port length, diameter, tuning, etc...)
Likewise, a question for
@TLS Guy , what does group delay look like in a TQWT, please? IIRC, the output from the Terminus is a full cycle behind, much like a Port, but unlike the Ported enclosure, the roll-off in the TQWT is second order.
(If I understand this correctly, a Port will allow Out of Phase SoundWaves to pass when they are away from the tuning frequency of the Port, but near the tuning Frequency, they come out in phase which is what loads the Driver in the Enclosure. Taking this further, the Out of Phase Soundwaves that emanate from the port are what lead to the fourth order roll-off as they are creating cancellations).
(Going back to the TL Terminus, the Backwaves are fully damped and do not emanate to create cancellations.At the tuning frequency of the Line, the output will be a full cycle behind, thus in-phase and fully supporting the signal.)
(I really hope I didn't make a 'dogs lunch' of that, Mark!
Just my attempt to test and see if I am getting these details.)
(That said, I am still most curious about the actual group delay of a TQWT compared/contrasted to a Sealed and Ported design).
A ported model I have is showing GD peaking ~56ms at 16Hz. Below 20ms at 20Hz. Comparing those numbers to the GD Graphs Shady posts in his Sub Reviews, this is well below one cycle.
Thank You!
R
