I am a bit dissapointed that one speakers distortion in 5Khz region is a lot higher than then other. Normal?

[puppet]

Don't forget that that 5.5khz reading is reflecting distortion products @11khz.

 

[Pdxwayne]

Cant see nearfield driver distortion. Grille causing distortion maybe. Is it not seated properly compared to other speaker?

The grill looks OK to me. I touch it and it is seated firmly.....

 

[Pdxwayne]

Don't forget that that 5.5khz reading is reflecting distortion products @11khz.

Yup, that part I am not sure my hearing is good enough to detect when 5.5 kHz is loud. Normal music listening seems fine. But I am a bit worry about higher distortion from 2khz up too. When playing music at 80db, I guess I won't hear 2% distortions?

Thanks!

 

[Pdxwayne]

Room issue, or mic mounting? Please play that 5,5kHz sine tone with REW's generator and try to locate the source of distortion by listening very close to the spaker. should be easy! Measurements further than 3´or 1m always pick up extrinsic sounds to some extent.

Toggle tags on the bottom of distortion window to show 2nd to 5th distortion separately. 2nd and 3rd are usually dominant and by my experience high odd order is typical for mechanical resonances. Resonances also are not lineat to spl, they need some energy to wake up and might suppress in % when amplitude gets too high. Nearfied at 1" will show only driver's problems, not those from the box, wire connections etc. and it is difficult to use high enough spl without overdriving the mic.

So, distortion is very difficult to measure and analyze, and an amateur must take several different measurements!

View attachment 119650

BTW, here is 1" measurements with 2nd to 5th harmonic included.

Thanks!

 

[jonfitch]

Seems to me even with that scary upward shape, it should still be at inaudible levels. It looks like about 2 % thd? I think the threshold of audibility should be above 3% assuming you are listening to pure test tones. Not sure if it's even audible during musical playback.

 

[Pdxwayne]

Seems to me even with that scary upward shape, it should still be at inaudible levels. It looks like about 2 % thd? I think the threshold of audibility should be above 3% assuming you are listening to pure test tones. Not sure if it's even audible during musical playback.

Yeah, at about 80db, as measured about 9.5 ft away, the max distortion is about 2.42% around 5.4khz. I don't know if I can even hear ~11khz second order harmonic when playing pure 5.4 kHz test tone. I will check later today.

I am mostly a bit disappointed that one speaker is much worse than the other, on paper. I expect perfection for top of the line bookshelves offering from a major company......
: )

Thanks!

 

[puppet]

If you're really serious about this you should pull the driver and test distortion. Too many outside variables to definitively blame the driver, otherwise.

 

[Pdxwayne]

If you're really serious about this you should pull the driver and test distortion. Too many outside variables to definitively blame the driver, otherwise.

Thanks!

With typical speakers, it would be very easy to pull the driver. I have done that to several of my others speakers.

But this one, the metal grill is on very tight. I am not sure how it was put on. Maybe like other said, screwed on. I don't want to force anything. I don't see any screws through the grill holes either. No screw holes from the back either.....So, I don't see a way yet to easily open up the speaker. I am especially not willing to break anything on a pair of speakers retail for US$7K.
: (

 

[Beershaun]

Thanks!

With typical speakers, it would be very easy to pull the driver. I have done that to several of my others speakers.

But this one, the metal grill is on very tight. I am not sure how it was put on. Maybe like other said, screwed on. I don't want to force anything. I don't see any screws through the grill holes either. No screw holes from the back either.....So, I don't see a way yet to easily open up the speaker. I am especially not willing to break anything on a pair of speakers retail for US$7K.
: (

Have you contacted the manufacturer? I'm sure they would be very interested to look at your measurements and help you understand what may be going on and figure out the problem. They may even have a licensed repair facility that your could take the speaker to for repair if necessary.

 

[Pdxwayne]

Have you contacted the manufacturer? I'm sure they would be very interested to look at your measurements and help you understand what may be going on and figure out the problem. They may even have a licensed repair facility that your could take the speaker to for repair if necessary.

Yes, contacted via online form. Waiting to hear back from them.

Thanks!

 

[Juhazi]

If nearfield shows difference in wide range, between L/R speaker, it is tweeter driver problem (misalignment of coil?). Peak at 5,5kHz is another issue then! Or same but happening only with higher spl.

 

[vavan]

Had similar experience with Lsim 705 and that allowed me to buy better speakers

 

[Pdxwayne]

Had similar experience with Lsim 705 and that allowed me to buy better speakers

Did you hear a difference between speakers?

Maybe in your case, the 2nd harmonics in the 5khz region is easier to hear?

Thanks!

 

[vavan]

Did you hear a difference between speakers?

I think I could hear something that made me want to return polks

 

[vavan]

Maybe in your case, the 2nd harmonics in the 5khz region is easier to hear?

I'm afraid I'm not so experienced to give definite answer to that, sorry

 

[Pdxwayne]

BTW, I played REW generated tones from 5.3 to 5.6 kHz and I can't really hear anything odd about it. I guess I am just not that sensitive to 11khz second order harmonic....

 

[mjwin]

This is interesting... It's good that you've taken several measurements here. But the fact that the indicated distortion peak depends on your measuring distance suggests to me that it might well be a resonance elsewhere in the speaker. Bass drivers usually don't have much response up high, but if the speaker uses a gentle crossover, this might well be the culprit. Or an internal wire resonance as someone has already suggested.

If you listen to the output of a slow frequency sine sweep, any critical resonances should be quite obvious by the change in timbre of the tone as you pass through the problem area. Though hearing a narrow band resonance at 11KHz might not be so easy, even with a sine tone. It certainly won't sound like "distortion" when playing music, and will probably be completely inaudible. In the olden days we used signal generators with a large knob which made it easy to sweep back & fore to locate the problem. Sometimes, technology gets in the way!

Personally, I'd suggest that you stick with measurements & try re-running the tests placing the measuring mic in as many different positions as possible, e.g. directly in front of the bass driver, or close to any metal trim. Keep the drive levels the same to avoid introducing another variable. You could also run a sweep with your finger held against the metal grille! Eventually you should be able to physically locate the problem which will be helpful to report to the manufacturers.

We don't know if this is a new speaker, one recently bought used, or something you've been using for years. The issue could have been present from new & you've never noticed it before because the problem isn't generally audible under normal conditions. It's not unusual to have anomalies such as this in speakers - just look at some of Amir's test results. I'm reminded of the old saying, "What the eye doesn't see, the heart doesn't grieve over".

 

[blueone]

You could also run a sweep with your finger held against the metal grille! Eventually you should be able to physically locate the problem which will be helpful to report to the manufacturers.

Good idea.

 

[Pdxwayne]

This is interesting... It's good that you've taken several measurements here. But the fact that the indicated distortion peak depends on your measuring distance suggests to me that it might well be a resonance elsewhere in the speaker. Bass drivers usually don't have much response up high, but if the speaker uses a gentle crossover, this might well be the culprit. Or an internal wire resonance as someone has already suggested.

If you listen to the output of a slow frequency sine sweep, any critical resonances should be quite obvious by the change in timbre of the tone as you pass through the problem area. Though hearing a narrow band resonance at 11KHz might not be so easy, even with a sine tone. It certainly won't sound like "distortion" when playing music, and will probably be completely inaudible. In the olden days we used signal generators with a large knob which made it easy to sweep back & fore to locate the problem. Sometimes, technology gets in the way!

Personally, I'd suggest that you stick with measurements & try re-running the tests placing the measuring mic in as many different positions as possible, e.g. directly in front of the bass driver, or close to any metal trim. Keep the drive levels the same to avoid introducing another variable. You could also run a sweep with your finger held against the metal grille! Eventually you should be able to physically locate the problem which will be helpful to report to the manufacturers.

We don't know if this is a new speaker, one recently bought used, or something you've been using for years. The issue could have been present from new & you've never noticed it before because the problem isn't generally audible under normal conditions. It's not unusual to have anomalies such as this in speakers - just look at some of Amir's test results. I'm reminded of the old saying, "What the eye doesn't see, the heart doesn't grieve over".

Pretty new speakers. It was used for about 1.5 year. Good idea about touching the metal grille.

Thanks!

 

[Pdxwayne]

I think now I could observe a difference between the speakers.

I listened to Nora Jones' "Come Away with Me" just now.

With the speaker with issue on the right, Nora's sibilance pretty excessive on the right. I switched speakers position and with bad speaker on the left, the sibilance now mostly more prominent on the left. : (

Fortunately my left ear is less sensitive to highs than right ear, so moving the bad speaker to the left reduced the impression of sibilance by maybe roughly 50%....