While not asked, the sharp edges would cause significant diffraction, which would be offensive to my ears.
I do think though that someone could get used to it and hear beyond it and make great recordings. But I certainly agree with Floyd, that this is not the right way to go about things.
In my system, which is highly thought of by many, I went to extremes to eliminate nearby (to the speakers) diffraction objects. To me this is critical in a playback system.
I do think though that someone could get used to it and hear beyond it and make great recordings. But I certainly agree with Floyd, that this is not the right way to go about things.
In my system, which is highly thought of by many, I went to extremes to eliminate nearby (to the speakers) diffraction objects. To me this is critical in a playback system.
why does the above measurements say 73db at ~20hz and the distortion looks to be about how they should, nearing xmax ~7%, meaning, virtually, limitation, thus no need to increase signal....
Atleast in my horn, I reach higher 2nd order distortion well before reaching max spl capability of the mic?
are you referring to 130db in some other way? I do notice that the headroom is low even though the readings are very modest... I thought that strange
At least it's wider than the average 2 way loudspeaker these days.
Now also available with... (I kid you not) Field Coil tweet and woof 😎 (there's some acoustic guitar after the hiphop).
Last edited:
Agree, in case of a 2 way with 1" dome + 8" woofer I would add roundovers such as these:
Funny you mention Avalon.
As a student I once had the opportunity to listen to a €250.000 Avalon + Spectral set, alone for about 1.5 hours.
Although I found the rendering too sterile/clinical - probably due to the ceramic drivers, I was confronted with 'an inky black background' for the first time (due to the absence of audible noise).
Since then, minimizing noise has been an important factor in audio for me
Last edited:
And to finish the round of yt videos, another simple 2 way system.
You can achieve 80-90% of this quality for less than €200
You can achieve 80-90% of this quality for less than €200
Camplo,
With the mic on a plane wave tube, at what I assume would be a 2.83V drive level, Celestion posts a graph with the Axi2050 driver output of 130dB SPL at 20Hz, rising to 140dB 200Hz-2kHz, falling to 120dB at 20kHz.
This would indicate the potential for 130dB at 20Hz, depending on mic placement and termination.
On the Seas30 horn, output at 20Hz is 40dB, midband reaches 110dB, 20kHz is 80dB.
In post 10,490 you post one graph of 20Hz at 88dB with 7% 2nd harmonic distortion at the throat (‘driver exit”) of your horn, another with 581%.
At that low a frequency, the Axi2050 diaphragm will likely reach it’s limits before the mic does.
Though they may show the output of a portion of the phase plug, neither give a representation of the driver/horn output potential at frequencies in it’s usable pass-band.
To get an idea of the relative levels from two meters distance compared to levels at the throat, I did this inverse distance test while evaluating HF compression drivers:
Even the B&K (Brüel & Kjær) 4004 test mic (<1%THD at 148dB, 130volt power supply) could be driven into distortion at the throat of a compression driver where levels can exceed 160dB peak.
Art
When we were doing PWT testing for nonlinear distortion perception at B&C, we ran into serious problem with the mic (as well as the amp) limitations at very high levels. It's not an easy thing to to, even with the best mics available.
I've always found that when this occurs you need to resolve it. Basically something has gone wrong and until you find it, all test results are decidedly suspicious.
Which microphone do you use?
The B&K mics are SPL/distortion kings, at a price, of course.
A more than adequate alternative:
iSEMcon EMX-7150, 146dB (3% THD).
Last edited:
As shown in post #10508, throat SPL may be 30dB higher than level at one meter. Peak levels could reach in the 160dB range.
The back electret condenser test mic you use has a maximum SPL level, above which the waveform is "clipped" off- it can't put out more level.
Though the fundamental frequency reaches a clipping point that won't go any higher, regardless of SPL, clipped lower frequencies result in harmonics within the audio band. The lower the frequency that is clipped, the more harmonics fit in the audible range.
Art
While these more extreme measurement practices are interesting from an R&D perspective, they are of little use from a reproduction POV, for which the usual measurements 1 meter or further from the mouth suffice. Both the driver and horn are fixed entities that you probably can't change much, other than e.g. adding a precision cut round piece of 30ppi foam to suppress diaphragm resonances.
BTW, I came across a possible 'matching' solution for the low mid/bass range
BTW, I came across a possible 'matching' solution for the low mid/bass range
"Peak levels could reach in the 160dB range." - During a sine sweep measurement I assumed that REW was reading peak. Its peak capture ability is not quick enough to capture the true peaks of the signal is what it sounds like you are saying, thus the loss of headroom.
And a B&K microphone will fix this. Since those are hard to come by. How might a Earthworks M30 or similar, fair out.
Attachments
Or I guess you could be saying that I can't take measurements on the exit, in the throat. Maybe back it off by several inches.
REW is reading RMS level during a sweep, peak level is 3dB higher than RMS for a sine wave.
Whether reading peak or RMS, a compression driver driven near full power can reach in the 160dBSPL range at the throat, but there is no reason to measure at the throat, or "several inches" from the throat- measuring inside a horn is not representative of what you (or your mic) will hear at a listening position.