Just quick questions:
What is the roll-off frequency of a transmission line and is there any difference between one without filling and with filling?
Does the taper change the roll-off?
What is the roll-off frequency of a transmission line and is there any difference between one without filling and with filling?
Does the taper change the roll-off?
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Transmission line covers a large range of alignments, the roll off can range from a 4th order roll-off (a basic ML-TL) all the way to (maybe) a bit slower roll-off than in a sealed box (ref: measurement of PR-2 aperiofdic loudspeaker) if damped till aperiodic.
dave
dave
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So, if I put damping material at the TL exit, would that give me a roll-off of second order or lower?
Would this also affect the SPL a lot?
Would this also affect the SPL a lot?
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You’d need a lot more damping than that, the entire lined would have to be filled and some density changes thruout the line might further help. In my aperiodic midTLs i start with low density near the drver and increas eit towards the terminus.
The geometry of the line will also play a role.
Now, with an ML-TL with a longish terminus restriction one might be ablle to get close.
As you increase the dampoing, reducing the primary resonance, the bass roll-off will start earlier but roll off slower. A good thing for tuning the line to the room.
SPL is not affected, boxes, except for front loaded horns do not affect SPL just how and what shape the speakers acoustic hiPass is.
dave
The geometry of the line will also play a role.
Now, with an ML-TL with a longish terminus restriction one might be ablle to get close.
As you increase the dampoing, reducing the primary resonance, the bass roll-off will start earlier but roll off slower. A good thing for tuning the line to the room.
SPL is not affected, boxes, except for front loaded horns do not affect SPL just how and what shape the speakers acoustic hiPass is.
dave
Putting any damping at the terminus of a TL is probably not going to produce good results. And yes, SPL will be affected. I recently measured an almost 3dB drop in output at Fb just by increasing the stuffing by 15L in a 40 Hz "straight" 100L TL I built recently.