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Multi-Way Conventional loudspeakers with crossovers

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Old 13th January 2020, 09:16 PM   #261
kipman725 is online now kipman725  United Kingdom
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Quote:
Originally Posted by kipman725 View Post
These results are very interesting the harmonic distortion at 130 dB seems similar to the JBL cone midrange horn loaded drivers in this tech note:
https://adn.harmanpro.com/site_eleme...e_original.pdf
Absolute SPL capability is of course lower, but as your results show the harmonic distortion is getting a bit much at 130 dB anyway.
Just realised that I misread the graphs. The CMCD harmonic amplitudes have +20dB added! so they are much lower distortion.
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Old 14th January 2020, 12:29 AM   #262
ErnieM is online now ErnieM  United States
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The BMS seems to measure better than I remember. Maybe because it's the HE version? I expected more distortion at both ends.
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Old 14th January 2020, 05:20 PM   #263
weltersys is offline weltersys  United States
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Originally Posted by mark100 View Post
Yeah, 10% is kinda an industry standard huh?....
Mark,

As one definition of reaching Xmax, yes.

As for high frequency drivers, where excursion is limited to under 1mm before contact with the phase plug, there seems to be no agreed upon standard.
It is rare to see distortion results above 5 watts (nominal impedance/voltage, not actual watts) as current HF compression drivers always exceed 10% THD well below rated power in the top octaves.

Art
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Old 14th January 2020, 05:57 PM   #264
mark100 is offline mark100  United States
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Originally Posted by weltersys View Post
Mark,

As one definition of reaching Xmax, yes.

As for high frequency drivers, where excursion is limited to under 1mm before contact with the phase plug, there seems to be no agreed upon standard.
It is rare to see distortion results above 5 watts (nominal impedance/voltage, not actual watts) as current HF compression drivers always exceed 10% THD well below rated power in the top octaves.

Art
Hi Art, i see your point. Food for thought......

Hey, semi related question for you....i keep perceiving a spectral tilt as i turn SPL up, keeping all else equal, that just sounds brighter.
It's with any of my various speaker builds, which all use either the bms or dcx CD's.
Do you think this perceived tilt could be due to a sensitivity to increasing THD, or should I be looking elsewhere? like maybe a psyche ward
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Old 14th January 2020, 06:18 PM   #265
kipman725 is online now kipman725  United Kingdom
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This is normal and due to how sound is perceived at different volumes, You should change the EQ to suit. There is an excellent document written by Rog Mogale that I have attached that tells you what to do.

*quick question for the more experienced; is the harmonic distortion performance we are seeing in the upper range of these comprehension drivers the best that can be achieved by single drivers?
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Old 14th January 2020, 06:34 PM   #266
mark100 is offline mark100  United States
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Originally Posted by kipman725 View Post
This is normal and due to how sound is perceived at different volumes, You should change the EQ to suit. There is an excellent document written by Rog Mogale that I have attached that tells you what to do.

*quick question for the more experienced; is the harmonic distortion performance we are seeing in the upper range of these comprehension drivers the best that can be achieved by single drivers?
Very good paper....very good recommendations ime/imo. Thx

My question though, is the perception due to equal loudness contours, or increased high frequency content due to rising THD levels?

Because it seems to me, the loudness contours level out at higher SPLs, giving us relatively less sensitivity to high freq content ????

Unless i'm reading the loudness contours' effect backwards, i'm left thinking 'where is the hf perception coming from'? THD is all i can come up with...
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Old 14th January 2020, 06:38 PM   #267
weltersys is offline weltersys  United States
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Originally Posted by mark100 View Post
Hey, semi related question for you....i keep perceiving a spectral tilt as i turn SPL up, keeping all else equal, that just sounds brighter.

Do you think this perceived tilt could be due to a sensitivity to increasing THD, or should I be looking elsewhere? like maybe a psyche ward
Mark,

Since all the "good" HF compression drivers seem to have increasing THD in the upper range, and distortion sounds "louder", sounds like it could be at least a partial explanation.

You could record the HF horns playing the same tune at widely different levels, then play back at the same level to confirm if the distortion sounds "brighter".

Or you could listen to the music recordings I did at different levels in High Frequency Compression Driver Evaluation
and be the first to report any difference you heard between the recordings!

Art
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Old 14th January 2020, 06:47 PM   #268
mark100 is offline mark100  United States
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Originally Posted by weltersys View Post
Mark,

Since all the "good" HF compression drivers seem to have increasing THD in the upper range, and distortion sounds "louder", sounds like it could be at least a partial explanation.

You could record the HF horns playing the same tune at widely different levels, then play back at the same level to confirm if the distortion sounds "brighter".

Or you could listen to the music recordings I did at different levels in High Frequency Compression Driver Evaluation
and be the first to report any difference you heard between the recordings!

Art
Wow Art, what a test . Have not seen that before...
Will study and try to digest....thx!
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Old 14th January 2020, 07:26 PM   #269
weltersys is offline weltersys  United States
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Wow Art, what a test . Have not seen that before...
Will study and try to digest....thx!
Pano's explanation of the tests in post #23 of the High Frequency Compression Driver Evaluation thread is helpful for "digestion" ;^).
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Old 14th January 2020, 11:31 PM   #270
Peter Morris is offline Peter Morris  Australia
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Hi Mark,

I suspect the best thing to do to get some idea of how these perform in the real world is to use a signal that approximates music such as IEC 268 Ė 5 which starts to roll off at 2kHz and is about 20 dB down at 20kHz.

The problem is that you really need to use a broad band sign of this shape and with the power being shared between the MF and HF section in accordance with the selected crossover points ... but thatís no good for measuring distortion levels.

The 464 has a large overlap between the MF & HF sections. This will allow the use of crossovers with slopes typically from 12 dB - 24 dB per octave. What I donít know is what happens through the crossover region where some of the same signal is shared with both drivers, it may reduce the distortion through this region Ö donít know. In the case of the 464 this will occur between 2-4kHz Ė ish and if there was a reduction and given the shape of IEC 268 / music this could be significant with respect to how we perceive these two drivers.

In your case you have used brick wall filters so Iím not sure how the results compare. FWIW I found I preferred using 24dB per oct. filters over brick wall filters when playing with the 464. With the 4594 because there is more or less no over lap at the crossover point of 6K3 there is an advantage with the brick wall approach.

The other thing to note is how we perceive distortion. We tend not to notice second harmonic distortion because its masked by the fundamental, however we are much more sensitive to third harmonic distortion, so its contribution to THD is much more important.
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