OK, it's a goofy title, but perhaps meant to indicate the tentative nature of any conclusions one might draw-
Got back to doing some driver testing this weekend. Eric Eva brought to my attention some test data published in Germany for a number of roughly 7" midbass drivers, including the Peerless 850439 and the 850467; his point was that based on their measured distortion data, which is lower int he 850467 phase plug version due to the additional of a top side Faraday ring, that I might want to use it instead of the 850439 in the high efficiency high output system Brian Bunge and I have been talking about. This improvement is noted in the midrange, from about 600 Hz on up, and is marked in the range of 1kHz to 1500 Hz.
Some driver manufacturers are noted for their concentration on one aspect of driver performance- Eton, for example, on their honeycomb kevlar and nomex cones- while falling short in other factors- again, Eton, with much higher midrange distortion due to overall mediocre motor design (IMO).
These tests were done only with 2nd and 3rd order harmonic distortion plotted, and are single tone- not a multi-tone test like the Praxis test Mark K has been running on a number of drivers recently.
Eric's comment was a good suggestion, and it got me to thinking some more about some tests I was planning on running - what I'd done the previous weekend was single tone FFT based, looking at all the visible harmonics. But it's very time consuming to cover a wide frequency range for one driver...
Here's an example for the Peerless 850439, at a drive level of 4 VRMS (2 watts at 8 ohms, 90 dB output nominal).
My recent update of CLIOWIN Standard supports harmonic display up to 5 th harmonic. OTOH, though I think my mic (B&K 1/2" condensor) and HP preamp are in good shape, they haven't been NIST calibrated in decades, so I only trust them in the sense of making relative and comparative evaluations, not absolute measurements. Still, I think this is useful, and learned some curious things, yesterday.
First, while I can't measure the absolute sensitivity of the drivers I wanted to test, I can do fairly accurate comparisions, such as between the Extremis 6, RS180, and Peerless 850439, all in the same test cabinet, all with the same 4VRMS verified at the speaker terminals with my Fluke 8922 Wideband True RMS AC voltmeter (and also monitored with my HP 500 MHz scop).
The Peerless is rated at 87.5 dB sensitivity for 1 watt (2.83VRMS), averaged between 100 Hz and 1 kHz. The Dayton is rated at 87.5 dB under the same conditions, and the Extremis 6 is rated at 86 dB.
How do they look? Here are the sweeps, measured at about 6" from the driver front (not my usual extreme nearfield), all in the same cabinet, drive voltage at binding post terminals checked to match within 10 mV.
Peerless Vs Dayton RS180 (Peerless is upper trace)
Peerless Vs. Extremis 6 (Peerless is upper trace).
Doesn't give you warm fuzzies' about manufacturer's sensitivity ratings, does it?
OK, how do they look, overall?
Keep in mind the distortion levels are raised 30 dB to make the graph size reasonable.
Extremis 6, 100Hz - 2 kHz
Peerless HDS 850439 100 Hz to 2 kHz
For reference, blue is 2nd Harmonic, Green is 3rd Harmonic, and Orange is 4th Harmonic. Fifth was genearlly down in the noise floor, and not worth plotting.
NO smoothing at all, here, folks, and their could be some noise contamination (one reason the FFT averaged test is quite good, if quite time consuming).
Got back to doing some driver testing this weekend. Eric Eva brought to my attention some test data published in Germany for a number of roughly 7" midbass drivers, including the Peerless 850439 and the 850467; his point was that based on their measured distortion data, which is lower int he 850467 phase plug version due to the additional of a top side Faraday ring, that I might want to use it instead of the 850439 in the high efficiency high output system Brian Bunge and I have been talking about. This improvement is noted in the midrange, from about 600 Hz on up, and is marked in the range of 1kHz to 1500 Hz.
Some driver manufacturers are noted for their concentration on one aspect of driver performance- Eton, for example, on their honeycomb kevlar and nomex cones- while falling short in other factors- again, Eton, with much higher midrange distortion due to overall mediocre motor design (IMO).
These tests were done only with 2nd and 3rd order harmonic distortion plotted, and are single tone- not a multi-tone test like the Praxis test Mark K has been running on a number of drivers recently.
Eric's comment was a good suggestion, and it got me to thinking some more about some tests I was planning on running - what I'd done the previous weekend was single tone FFT based, looking at all the visible harmonics. But it's very time consuming to cover a wide frequency range for one driver...
Here's an example for the Peerless 850439, at a drive level of 4 VRMS (2 watts at 8 ohms, 90 dB output nominal).
My recent update of CLIOWIN Standard supports harmonic display up to 5 th harmonic. OTOH, though I think my mic (B&K 1/2" condensor) and HP preamp are in good shape, they haven't been NIST calibrated in decades, so I only trust them in the sense of making relative and comparative evaluations, not absolute measurements. Still, I think this is useful, and learned some curious things, yesterday.
First, while I can't measure the absolute sensitivity of the drivers I wanted to test, I can do fairly accurate comparisions, such as between the Extremis 6, RS180, and Peerless 850439, all in the same test cabinet, all with the same 4VRMS verified at the speaker terminals with my Fluke 8922 Wideband True RMS AC voltmeter (and also monitored with my HP 500 MHz scop).
The Peerless is rated at 87.5 dB sensitivity for 1 watt (2.83VRMS), averaged between 100 Hz and 1 kHz. The Dayton is rated at 87.5 dB under the same conditions, and the Extremis 6 is rated at 86 dB.
How do they look? Here are the sweeps, measured at about 6" from the driver front (not my usual extreme nearfield), all in the same cabinet, drive voltage at binding post terminals checked to match within 10 mV.
Peerless Vs Dayton RS180 (Peerless is upper trace)
Peerless Vs. Extremis 6 (Peerless is upper trace).
Doesn't give you warm fuzzies' about manufacturer's sensitivity ratings, does it?
OK, how do they look, overall?
Keep in mind the distortion levels are raised 30 dB to make the graph size reasonable.
Extremis 6, 100Hz - 2 kHz
Peerless HDS 850439 100 Hz to 2 kHz
For reference, blue is 2nd Harmonic, Green is 3rd Harmonic, and Orange is 4th Harmonic. Fifth was genearlly down in the noise floor, and not worth plotting.
NO smoothing at all, here, folks, and their could be some noise contamination (one reason the FFT averaged test is quite good, if quite time consuming).
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