we bought a pro audio company last year (one of the largest in the world) and they are doing some competitive testing of amps and speakers. here is a particular speaker (by a well known high-end brand name) and its thd figures:
2nd harmonic:
100hz: about 10%;
1000hz: about 0.5%;
10Khz: about 5%
3rd harmonic:
100hz: about 10%;
1khz: about 0.2%;
10khz: about 0.5%.
who said they could hear 0.00001% thd?
2nd harmonic:
100hz: about 10%;
1000hz: about 0.5%;
10Khz: about 5%
3rd harmonic:
100hz: about 10%;
1khz: about 0.2%;
10khz: about 0.5%.
who said they could hear 0.00001% thd?
Those numbers are kind of meaningless without reference to drive and SPL.
sss: One easy way is to drive the speaker with a sine wave, look at the acoustic output with a mike and preamp, then either take an FFT to determine harmonic content (an apodization is necessary!) or use a plain vanilla distortion analyzer or wave analyzer.
sss: One easy way is to drive the speaker with a sine wave, look at the acoustic output with a mike and preamp, then either take an FFT to determine harmonic content (an apodization is necessary!) or use a plain vanilla distortion analyzer or wave analyzer.
SY said:
yes, SY. when the Mars and Pluto are exactly lined, and Saturn's 3rd and 7th satellites are exactly perpenticular to the earth, you cannot observe any speaker distortion.
I don't have all the specifics, but the measurements are done in a sound chamber with the mic placed 1m from the speaker center.
But doesn't that make the measurement totally useless? since no one listens to their speakers in a sound chamber.
cunningham said:
A-MEN
also typically you can almost eliminate speaker distortion by never exceeding 60% or so of rated RMS power.
Certainly power compression will be reduced...but the actual cone movements is the worrying thing if talking of low frequencies.
hundred or two watts applied to a shiva 12" can bottom it at 20hz,but whatabout at 90hz! its only thermally limited there.......
this is not really the case.
I did measurements with my speakers and Zen / chipamp. At low volumes the crossover distortion of the chipamp has a larger number that the distortion caused by the speaker.
In case they measured 1m from speaker at rated power, and this were PA speakers, i doubt they had a mic they did not overdrive. And speakers distortion starts at very small numbers and gets larger with power. Just like SE class a amplifiers. Not so psuh pull amp, they start with bad THD, get better with more power, and worse when going near to rated max. power.
So yor conclusion is right in case you listen at high volume levels / high power feed into speakers. Thats not the typical usage.
All one needs to test the speakers distortion is a PC with soudncard and a good mic. Why not measure?
The numbers above without giving power, spakers data, measured bandwith etc.. are meaningless. I suspect the thread starters point is the same kind of "point" he has for his ridicolous postings in off topic forum.
Hi Till,
You could be right about the low power lineairity of speakers. I suspect the distortion figures of a speaker to be more of less proportional to the input voltage (below it's rated power). And indeed it should be interseting to try to measure that. I think Linkwitz has done such measurements and publshed them on his website.
Could you elaborate a bit on the quantitative data of your measurements. I am a bit scepitcal about your remarks on your Zen/Chipamp measurements, as my gainclonne has 0.01% THD at 1 Watt (measured). Can you measure such low aucoestical distortion figures?
Best regards,
Thijs
You could be right about the low power lineairity of speakers. I suspect the distortion figures of a speaker to be more of less proportional to the input voltage (below it's rated power). And indeed it should be interseting to try to measure that. I think Linkwitz has done such measurements and publshed them on his website.
Could you elaborate a bit on the quantitative data of your measurements. I am a bit scepitcal about your remarks on your Zen/Chipamp measurements, as my gainclonne has 0.01% THD at 1 Watt (measured). Can you measure such low aucoestical distortion figures?
Best regards,
Thijs
Thijs,
My TD2001 will produce about 109dB at 1m distance at 1W.
I do not claim my measurements beeing of scientific quality, but be sure i measured at much below 1Watt also. A FFT will be able to detect THD also at very low signal levels.
The very low power levels i use for normal listening may be the reason why chips etc. sound worse than the ZEN with my speakers.
My TD2001 will produce about 109dB at 1m distance at 1W.
I do not claim my measurements beeing of scientific quality, but be sure i measured at much below 1Watt also. A FFT will be able to detect THD also at very low signal levels.
The very low power levels i use for normal listening may be the reason why chips etc. sound worse than the ZEN with my speakers.
Hi Till,
I don't expect you to have done acoustical distortion level measurements at 109dB, your speakers seem to be a bit above average efficientcy... But I am not so much interested in speaker efficinetcy (I asume you use average listening levels (80-90dB?) for testing?) , but I am interested what acoustical distortion levels you did measure and what distortion levels you have measured at the output of your amp as comparison. You stated that
Also.. after some thinking.. . it is the SPL related excursion that gives rise to the speaker distortion, so high efficient speaker in it self don't help against speaker distortion, or does it? It does however help agianst amplifier distortion, so in your situation, speaker distorion sould be especially domminating? The Zen amp btw has >0.01% THD at 100mW (about 89dB SPL from your speakers), which is higher than a GainClone?
Cheers,
Thijs
I don't expect you to have done acoustical distortion level measurements at 109dB, your speakers seem to be a bit above average efficientcy...
But I am not so much interested in speaker efficinetcy (I asume you use average listening levels (80-90dB?) for testing?) , but I am interested what acoustical distortion levels you did measure and what distortion levels you have measured at the output of your amp as comparison. You stated that
.. I'm still a bit scepical, but I am sincerely interested in such meusurements..
Also.. after some thinking.. . it is the SPL related excursion that gives rise to the speaker distortion, so high efficient speaker in it self don't help against speaker distortion, or does it? It does however help agianst amplifier distortion, so in your situation, speaker distorion sould be especially domminating? The Zen amp btw has >0.01% THD at 100mW (about 89dB SPL from your speakers), which is higher than a GainClone?
Cheers,
Thijs
I did not write down notes about it, i remeber the following: measurements done at frequencies above 600Hz, the cone speaker used below does distort more at higher volumes. All THD values measured were below 1% at about 1W. With the Chip about 2 to 4 times higher than with the Zen in the range below 1W. Unless very loud not really more THD with speakers than measured electrical at amps output. There is some level of volume were speakers THD increases drastically, below the rated power of the speaker. I measured at lower volume levels (no absulolute dB meter here) and the distortion from the amp was dominating here, and with really loud levels (ear protection!) and speakers distortion was dominating. My conclusion was measurement confirm my ear: at last with my high efficient speakers SE class a are better. In case there is interest i will do better measurements, but not in the next few weeks as i have to move all audio gear in a new room first.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.