Hello,
The clues that Tom gave us about the tapped horn are very usefull. I never looked it that way. From the post`s that Tom and Mark placed in the past about, aspecial the one`s of the unity horns, i learned a lot about phase/time issues, still i have questions about this most important subject. The textbooks i have don`t give me the answers so maybe you guys could fill in.
Correct me if i'am wrong.
I am totally confinced that a speaker can only produces the exact same waveshape as the signal you supply it if you have absolute zero phase and a flat amplitude respons. Other words; the position of the speaker is exactly the same as the "point" is in the signal, so no delay.
The time delay between the supplied signal and the time that you "catched" the sound with your mic consist of three things:
- Time of flight (no frequency depending)
- Group delay (frequency depending and can be calculated out
the equivalent circuit)
- The internal delay of the speaker itself.
This last delay is my biggest problem when i am trying to design the "perfect" speaker. I think this delay is the difference in measuring a speaker with a TEF machine (conform TDS) and most of the other programms that don`t measuring the absolute acoustic phase. Is this delay frequency depending or is it a constant delay? And what can a speaker tell us about it if we looking to his parameters or it construction?
Most of the diy-ers can`t afford it to buy something like the TEF machine, but what can be done to make the ideal speaker? And how far must be go, if we talking about the perfect speaker. For example; must the phase delay of a mic. also be counted in when measuring a speaker?
Ps.: with the ideal speaker i mean it`s going to act like the way you wanted to act.
Well i have to go.
Cheers,
Marcel