This looks awesome and "correct"
some questions:...- is that 10" or 8" woofer?
- How did you bend the metal poles ?
As for finding out pipe resonance, normally I just lift the speakers a bit and poke the microphone. I'ts very revealing.
Ha! you never told me that. But this is exactly one 'issue' I could not fix with my Pluto clone!
I measured the pipe resonance via impedance and FR and could see them 210hz...420hz... etc. from memory. Tried this and that with damping but in the end they were still 'audible'. I even tried notching *every* peak at one stage
Here is my effort at omni speakers.
I enjoy them very much but wish I had some measurement equipment to show me changes in x'overs etc. Perhaps Santa will be nice to me this year.....
As it is I use a single cap of 6.8 ufd to crossover 1st order around 7 kHz - and that's it.
There is more info over at this old thread - but it is a very long thread: http://www.diyaudio.com/forums/multi-way/100390-ohm-acoustics-walsh-f-speaker-remakes-6.html
I enjoy them very much but wish I had some measurement equipment to show me changes in x'overs etc. Perhaps Santa will be nice to me this year.....
As it is I use a single cap of 6.8 ufd to crossover 1st order around 7 kHz - and that's it.
There is more info over at this old thread - but it is a very long thread: http://www.diyaudio.com/forums/multi-way/100390-ohm-acoustics-walsh-f-speaker-remakes-6.html
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This looks awesome and "correct"
- is that 10" or 8" woofer?
- How did you bend the metal poles ?
As for finding out pipe resonance, normally I just lift the speakers a bit and poke the microphone. I'ts very revealing.
It's a 10". Same Peerless unit as the Pluto sub. Poles were bent in a special way
. Meaning I had a shop do it. Poke the mic? What's that?
The fullranger was a Ciare HX201 with massive treble rise, so that direct sound plus treble reflection gave a fairly good frequency response.
I hate dipole airiness, so I prefered it in a closed or almost closed setup.
Only for bass. Not in a range where wavelength compared to the size of the driver basket becomes significant.
Even Pluto has it. It is just a matter of audibility. Maybe here the alu membrane has a slight advantage over less rigid materials. But at this stage the statement is speculative.
The graph is highly misleading because just a single measurement was used to generate the sonogram. You can use any single measurement to generate such a graph. It even doesn't need to be flat if normalization is used.
For such a concept it would be more interesting to see a vertical sonogram. Unsmoothed, free field, mic at about 2m distance and not at 1m.
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errr... I think you underestimated the design prowess of Herr 2Pi
He was the one who taught me sonograms. Many sonograms was produced thereafter.
errr... I think you underestimated the design prowess of Herr 2Pi
He was the one who taught me sonograms. Many sonograms was produced thereafter.
So what's wrong with what I've said?
That the graph is misleading ?
Yes, because
a) the infinite number of horizontal points is replaced with just a single data point (measurements should prove or disprove a hypothesis, here it's just an illustration of the hypothesis)
b) normalization masks any resonance
c) the mic is too close, i.e. not in the far field
c) With such a small driver the mic is in the far field at 1m distance
a) I verified that the response did not change horizontally. So it does not matter if I use 1, 2, 3 or much more measurements. The time that was saved to take snap shots every 5° or 10° or whatever degrees is spent well elsewhere.
b) agreed on normalization. That's why I also show other diagrams and mention that it is normalized.
Compare the vertical measurements. There I went the full 9 yards because the response does change.
a) I verified that the response did not change horizontally. So it does not matter if I use 1, 2, 3 or much more measurements. The time that was saved to take snap shots every 5° or 10° or whatever degrees is spent well elsewhere.
b) agreed on normalization. That's why I also show other diagrams and mention that it is normalized.
Compare the vertical measurements. There I went the full 9 yards because the response does change.
Yes? There's a diffraction device involved. Did you confirm with measurements?
How did you verify if not by measurements??
Could you also posts a sonogram with vertical data?
Yes, if I remember correctly I went up to 1.7m.
I did measure it ! I probed one side with one of the little poles. Then I compared the graphs by substracting them from each other. The result was a flat line. Only the calculation/the picture is based on one measurement because it would have made no difference.
I have no reason to cheat here. I am not afraid of the work. One intention of the horizontal sonogram was and is to show that nice pictures cannot describe how a speaker really sounds regardless of how perfect they are.
If you can read that better than the polar plots I can do that (next week).
Thanks for the additional information.
Well, one can read that graph one way or the other. I obviously chose the wrong one
Would be nice.
Well, one can read that graph one way or the other. I obviously chose the wrong one
Would be nice.
There you go. Again, 0° is on listening axis. + is up and - down.
This is normalized. The exact same data that is published on my site as polar plots.
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