Bengt Nilsson
Registered
Thread Starter
- Joined
- Aug 3, 2018
- Posts
- 4
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- Main Amp
- Marantz PM 6004
- Additional Amp
- Musical Fidelity A1
- Universal / Blu-ray / CD Player
- N/A
- Front Speakers
- Fostex FX120 b/ SEAS A26RE4
Hi,
This is probably a fundamental driver physics question, I may not have the proper understanding here.
When I have measured SPL and phase for low and medium frequency drivers, I have studied the phase response and step response.
I have seen that if I have a positive step response I can adjust the time offset using "Actions" so that I have a range in the phase response that is reasonably flat around zero.
If I do the same with the sound card "invert", I get a negative step response and I can get similar range flat around 180 degrees.
This makes sense.
Now, I am testing an old Celestion HF1300 tweeter, and I am surprised of what I see.
The SPL response is not exactly flat, but ok for this vintage unit.
I set sound card "invert" so that I get a positive step response. It is due to my wiring,
Now, I can only get a flat phase region around 90 degrees, not zero.
If I set it to a negative step response, I can get a flat phase region around -90 degrees.
Can someone more experienced explain to me why this is?
Is this specific to tweeters only?
Or is the HF1300 special in this respect?
It has a quite massive phenolic diaphragm compared to moden domes.
BN
This is probably a fundamental driver physics question, I may not have the proper understanding here.
When I have measured SPL and phase for low and medium frequency drivers, I have studied the phase response and step response.
I have seen that if I have a positive step response I can adjust the time offset using "Actions" so that I have a range in the phase response that is reasonably flat around zero.
If I do the same with the sound card "invert", I get a negative step response and I can get similar range flat around 180 degrees.
This makes sense.
Now, I am testing an old Celestion HF1300 tweeter, and I am surprised of what I see.
The SPL response is not exactly flat, but ok for this vintage unit.
I set sound card "invert" so that I get a positive step response. It is due to my wiring,
Now, I can only get a flat phase region around 90 degrees, not zero.
If I set it to a negative step response, I can get a flat phase region around -90 degrees.
Can someone more experienced explain to me why this is?
Is this specific to tweeters only?
Or is the HF1300 special in this respect?
It has a quite massive phenolic diaphragm compared to moden domes.
BN
