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Well, true, just forgot to add that it was in terms of low-pass filters.Granted, the phrase is often in the context of lowpass filters...
Well, true, just forgot to add that it was in terms of low-pass filters.Granted, the phrase is often in the context of lowpass filters...
What "might" happen when you send a 200Hz square to the speakers, if you have a sub and a two-way:
(repaired image)
View attachment 73150
Not quite, brickwall filters are known as linear-phase filters. They actually preserve the phase of the original signal or try to preserve the signal as much as possible.
The perfect brickwall would be perfectly linear-phase, but we cannot implement this due to constraints in physics. The phase is kept because the relationship between the frequencies and their respective phases is linear and it is multiplied by a single slope number which represents the phase shift gradient. All-pass filters are filters that even though do not filter anything, change the phase of the frequencies where it is placed. A filter only changes the phase in its point of action, so what you said is correct.After pondering this for about 5 seconds ... I expect this is because there is no attenuation until right up on the crossover point, and where there is no attenuation, there is no phase gradient. Correct?
No, that filter you are describing is a notch filter or a high-pass filter. Brickwalls are low-pass filters, which if you place it around 20 Hz, anything above that frequency will be filtered. High-pass filters are the ones that filter frequencies below a cutoff.
The tweeter's output should be the aggregate of all off harmonics of 200 Hz above 1 kHz, i.e., 1.4 kHz, 1.8 kHz, 2.2 kHz, 2.6 kHz
I understand that I made the mistake to forget that you can model a brickwall transition to work with high-pass filter (it is just a way to handle the transition band regardless of the type of filter used).What dc655321 wrote is correct and on target. The term "brick wall" alludes only to steepness of attenuation slope. What I was trying to say (and believe that I did say in an adequately clear manner) is that if the low-pass filter that is applied is sufficiently steep, that there will be no remnant of the original 15 Hz fundamental in the output waveform, and that the overall periodicity evident in the output waveform will be that of the 3rd harmonic (45 Hz). In retrospect this was probably too obvious, however in my prior post I had written something that was not entirely correct and I wanted to correct it. And if it was too obvious, it was not more so than your having written: "High-pass filters are the ones that filter frequencies below a cutoff."
A 15 Hz square wave consists of sine waves 15 Hz, 45 Hz (3*15), 75 Hz (5*15), 105 Hz (7*15) ...
Now you take away 15 Hz and get a lowest frequency 45 Hz. So far ok.
But 75 Hz is not 3*45, 105 Hz is not 5*45 ... Thus the filtered result is no longer a square wave.
There is nothing best, sorry. Everybody searches for the holy grail but the problem is that there is no holy grail. And HEY, in my age I can do what I want and I am no rap. Other people do that for me in my company. Actually I can give you only one hint : If it sounds bad it is bad, if it sounds excellent it is excellent. Too many parameters involved to get a grasp on it. Mostly it is a poor setup that makes the poor sound. Especially speaker placement is little understood and mostly is limited by pseudo aesthetics.
Yes.
Analysis:
The odd harmonics combine to create the "flat" high/low of the square.
Removing the low frequency removes the offset from 0, leaving the flat part, approaching 0.
Here's the tweeter with dB - looks like, since it is bandwidth limited, it only gets down to about -80dB here...
View attachment 73178
I understand that I made the mistake to forget that you can model a brickwall transition to work with high-pass filter (it is just a way to handle the transition band regardless of the type of filter used).
The perfect speaker will go unnoticed, Peter Walker.
Then you are more sensitive to timing then other parameters. Yes, a 3 dimensional image matters a lot to me too. I am not a flal earther at all.