Basically four 2-ways per speaker (one on each side) so four baffles per speaker. Not sure about different heights and Idk if it was a gimmick or it actually worked.
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I give up.
The main lobe that you thought to vanish in a continuous signal did not vanish
My question why filtering the cymbal file at 44 was the wrong decision remained unanswered and a Gibbs envelope is still a mystery to me.
I don’t even know if we disagree, we simply use different languages causing that I still haven’t got a clue what exactly you are trying to tell.
Hans
I think part of the discussion is about what we mean with sufficient.
My take would be audible, but I guess JN means measurable?
I thought time invariant was a property of a system or an operator? How is it defined for a signal?
/örjan
Still further to the "seemingly frequency shift" that I mentioned above: the time domain signal that we see is the sum of all signals, but what we hear are individual frequencies.
So when two or more added frequencies suggest a frequency shift, we still hear the individual frequencies.
That's the case when subtracting Gibbs frequencies and the "above Brick Wall frequencies" from an Audio signal.
Seemingly the remaining signal may be shifted in frequency, but the FFT shows that every frequency is still correctly where it should be, just like what we hear.
Hans
So when two or more added frequencies suggest a frequency shift, we still hear the individual frequencies.
That's the case when subtracting Gibbs frequencies and the "above Brick Wall frequencies" from an Audio signal.
Seemingly the remaining signal may be shifted in frequency, but the FFT shows that every frequency is still correctly where it should be, just like what we hear.
Hans
Probably I'm reading this wrong but are you saying that lets say an 19 kHz signal passed through an 20kHz low pass filter would be frequency shifted? Or only if its modulated?
/örjan
orjan, KSTR's posts between the 5th and 9th Jan explain it IMO, particularly those on the 9th if your haven't read them https://www.diyaudio.com/forums/search.php?searchid=22238482
Oh, it's just the first page of his posts using the member search function. Does this work https://www.diyaudio.com/forums/search.php?searchid=22238482
Oh well, nevermind 🙂 I don't know why that should be, orjan has found the posts anyway 😉 Just first page of "find more posts by KSTR"
Good, I found his explanation cleared things up for me. The argument was becoming a bit of a "black hole...." 😉
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Where did I say that I thought the main lobe would vanish???
A cymbal file has far to much complexity to be useful as a diagnostic other than "something is different".
A Gibbs envelope is the shape and form of the difference between input and output, as Scott pointed out it was at Gibbs frequency.
We certainly agree on that.
It is very very simple. Overlay your input signal on your output single on a single plot. The frequency will be different, the envelope will be different.
Yet you seen to be claiming they are the same.
jn
The initial claim by others was that cymbals at 44 rate are audibly different from that taken at higher rates.
I detail the issue of signals near Fs that are amplitude modulated such that the resultant filtered output excludes one of the sidebands caused by amplitude modulation.
what I meant was, during the actual exponential, the frequency is changing. That is why an FFT of an exponential waveform has a broad fuzzy spectra on an FFT. Using that signal as a modulator puts that broad fuzzy spectra on the primary signal's fft as well. An FFT cannot easily show that the spectra is changing over time, it just shows total energy over a specfic span.
jn
No, it doesn't. Your FFT plots show that very clearly. to wit, the second is missing the upper sideband, the first has it all.
The FFT's are showing very different signals. And your time domain plots before and after VERY clearly show that.
Edit...in fact, you put in a 20K modulated by a 4k, but the filter output is an 18K modulated by 2k.
The next question should be...did I just guess that, or was math involved?😉
jn
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From the days when i took entry level grad school sampling frequency i came up with a more graphic description. It is like a big Monty Python foot coming down out of the sky and squashing the music with stuff splattering everywhere.
dave
A big panel speaker is a variation on the line array. The thread on infinite line arrays shows that there is a 3dB/octave drop in HF response and this shows up in a nearfield measure.
dave
A speaker that left a huge impression on me when i heard them in the early 70s. But i really like the simple concept for filling a large (not listening) room.
dave
Four EPI 100s mounted on the 4 sides of a 6 foot tall, slim tower with black full height grills, and solid wood corners with )golden) aluminum accents.
dave