Yes, I agree entirely and catch myself often enough in my own web of self contradiction to safely assume I do it way more than I think I do.
Perhaps my language was off but I had meant my comment a bit more tongue in cheek, albeit frustrated and critical of him entirely offhandedly dismissing a body of research (that spans past just Dr Gedlee). So apologies if it came across mean spirited.
This came up elsewhere and it's worth repeating. I'm almost certain the high distortion numbers thrown around are referring to the woofer at high excursions. A quick look found no speakers that didn't fall off dramatically after 200Hz or so. THD @1kHz is even more useless as a FOM for speakers. If this was that much of a problem everyone would try current drive. 🙂
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The fact of higher speaker distortion at low frequencies is well known and considered.
Re voltage x current drive, some measurements made few years ago
Current drive of speakers and speaker distortion
The only improvement with a current drive was for a woofer in a closed box.
Re voltage x current drive, some measurements made few years ago
Current drive of speakers and speaker distortion
The only improvement with a current drive was for a woofer in a closed box.
I measured the effects of current drive on a number of drivers using an amp with variable output Z. The results were all over the place. Some do better on the low end with CD and worse on the high end, and the reverse can also be found. Etc. But, in all, the differences were minimal and not worth the effort.
Uh. and why are we using distortion numbers from a speaker with only a miserly 2 volts on it? This isnt a preamp etc. 1% thd at 2volts. Come on. Play that thing as if you were listening to music with it at home with typical speaker efficiency.
Even with high effic M2 speakers, I average 20-30W music pwr for reasonably loud spl at listening distance (not an inch or even 1 meter. Maybe lower effic skrs require more than mine? What ever, just do tests the way we use the DUT in home and 'normal' spl at 8-10' or so. Remove the room with software or use an anechoic chamber.
But back to CD.... that is the important thing invented ... the control of directivity and why would you want to and how to do it. Geddes showed a way with conical horns and got a patent on it. OK.
THx-RNMarsh
Even with high effic M2 speakers, I average 20-30W music pwr for reasonably loud spl at listening distance (not an inch or even 1 meter. Maybe lower effic skrs require more than mine? What ever, just do tests the way we use the DUT in home and 'normal' spl at 8-10' or so. Remove the room with software or use an anechoic chamber.
But back to CD.... that is the important thing invented ... the control of directivity and why would you want to and how to do it. Geddes showed a way with conical horns and got a patent on it. OK.
THx-RNMarsh
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If I were driving my speakers as if I were playing them at home (and no I haven't done distortion measurements), it'd be closer to 20-200 mV versus 2 volts, much less 20+ volts. I listen pretty quietly and nearfield.
We all have different design constraints.
We all have different design constraints.
I do so by SW in newer measurements, as in the current test on audibility of speaker distortion. Unable to remove from older jpg images.
M2 quoted sensitivity is 92dB/w at 1m. For a THX level of 85dB at listening position your RMS should be around that surely?
Of course, Richard -- the big point I was trying to make was "We all have different design constraints". We need be careful to not generalize our personal perspectives. 🙂
Also as you move up in volume, the amount of perceptual masking increases, so mind that.
Also as you move up in volume, the amount of perceptual masking increases, so mind that.
And the ear has high intrinsic distortion at high SPL level. Speaking about lowest ear distortion and lowest masking, the SPL should be 80 - 90dB.
Yes..... That is a reasonable level. And reaching that level at 1 meter does not take much power compared to - say - 10 feet away and getting 80-90db SPL. The amp power is higher into driver to do that level further away and distortion would be higher as well.
As speaker power goes up past 1W, so does thd. Realistic listening levels at distances further away than most testing is done, show higher thd levels.
WE havent even talked about IM !
THx-RNMarsh
As speaker power goes up past 1W, so does thd. Realistic listening levels at distances further away than most testing is done, show higher thd levels.
WE havent even talked about IM !
THx-RNMarsh
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The IM is in my speaker test files, recorded at 5.66Vp, and is the most audible.
BTW Wolfgang K does a great job, number one currently.
BTW Wolfgang K does a great job, number one currently.
Well taking THX again as 85dB ref -20dBFS . 3m listening distance is 10dB down. So needs 2W. But it's active so, more music signals as low as 0.5W. Peak is 50W ish per amp unless I have missed a factor somewhere?
I use my system (Onkyo TX-NR838, 1977 Klipsch Hersey) with my TV as I have hearing problems. I find I can hear better with the stereo than the crappy sound system in the TV (Samsung UHD Series 7 7090).
I just checked my spl at 11ft from the speakers (setting position on the couch) and hit about 60dB peak. I used a RS SPL meter (fast response, C weighted) which has been referenced to a Minidsp UMIK-1 with REW.
Yes, Not exactly professional, but it should get me "in the ballpark" so to speak.
Upstairs in the kitchen I hit 80dB on peaks with what I would consider moderate levels (when no one is home and I'm cooking). Same model speakers, tube amp.
I would consider 90dB full on party rock.
I just checked my spl at 11ft from the speakers (setting position on the couch) and hit about 60dB peak. I used a RS SPL meter (fast response, C weighted) which has been referenced to a Minidsp UMIK-1 with REW.
Yes, Not exactly professional, but it should get me "in the ballpark" so to speak.
Upstairs in the kitchen I hit 80dB on peaks with what I would consider moderate levels (when no one is home and I'm cooking). Same model speakers, tube amp.
I would consider 90dB full on party rock.
I also augment my TV sound with and extra amp and speakers. I use a Parasound HCA1000 that is about 20 years old every day, with a pair of Sequerra MET7's in front and an other pair of MET7's in the rear, as well as a VMPS subwoofer. Because I do not turn it up too loudly, (usually below 90spl) the amp drives the whole array of 5 speakers without any obvious problem. This is, of course, not my reference system, but I put a lot more time on the MET's than my big rig. Yes, there is a difference in performance and resolution between the two systems, but with average sources, such as TV, I doubt that the bigger system would be as comfortable to listen to. Forgiveness in the MET7's is often a good thing.
If we are still talking about 'critical listening' and not "likes" again, 80-90 is needed to hear all freqs ....
Now we can dig a little deeper ---
View attachment Bass dist 1.pdf
View attachment Basss dist matters 2.pdf
3rd and higher harm would be more easily detected. And higher than 2nd (H2) is very common. And, we still havent talked about IM.
NOTE: again, standard measurement data referred to (eg 6% as common) is measured at 1W/1 meter.... not the conditions at home listening.... quit and easy test.
THx-RNMarsh
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