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Old 26th October 2019, 11:48 AM   #131
augerpro is offline augerpro  United States
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Originally Posted by 5th element View Post
The complainant people have with metal tweeters is that the distortion products, while beyond our hearing, will introduce IMD products back into the audio band. At least theoretically, the level that these would be at would be very low down in level. Still this is why stiffer domes are desired, so that breakup is pushed even higher and the distortion products would be pushed up too.

If the textreme gives pistonic operation up to 20kHz but doesn't present with any distortion products then there's the theoretical advantage.
I always hear this, but no one has ever shown this to be the case. Seems a simple thing to test with multitone measurements. I won't say I've never seen a subharmonic, but it's been pretty rare, low level, and discreet. My second objection is that considering how rare HD audio is, how would one even energize this breakup with the Redbook CD cutoff being lower than the breakup?
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Old 26th October 2019, 01:11 PM   #132
andy19191 is online now andy19191  Europe
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Originally Posted by augerpro View Post
I always hear this, but no one has ever shown this to be the case.
Indeed. The size of the required non-linearity, the proportion that could be aliased into the audible range, the level of the ultrasonic signal in music,... all lead to it being too small to be audible. Which is of course why hard domes are widely used by the industry although on a flat baffle without waveguides I suspect one might make a case for the directivity of soft domes being preferable.

Now using a stiff material to make a larger dome rather than push the resonances unnecessarily higher would make more engineering sense. The manufacturers are presumably aware of this but it seems to be in conflict with the current marketing situation which enables the use of stiff cones in exotic materials with resonances on graphs well above those of cheap stiff materials to command a premium price and get bought in significant and profitable numbers.
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Old 26th October 2019, 01:42 PM   #133
briskly is offline briskly  United States
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This paper would be of relevance to sub-harmonic and other types of non-harmonic distortions generated by a single input tone.
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Old 26th October 2019, 05:03 PM   #134
Oneminde is online now Oneminde  Sweden
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Talking about break up modes, audible issues, IMD etc. (video link) Tidal vs Qobuz: Battle of High-Res Streaming Services- they analyze both services and find some interesting data and talk about the ability to hear high res audio. The only thing I can say about the difference between 16/44.1, 24/96 or 24/192 is that content beyond 25kHz add clarity, soundstage and imaging. To some degree, dynamic range can have an affect. Its not noticeable on all tracks and albums, but there is an overwhelming benefit and enjoyment. I'd rather have a 24/96 or 24/192 high bitrate than not.

I am more into owning my albums rather than having to pay for a streaming service. While it has advantages as in being cheaper in the long run due to the share amount of albums you can "collect" per month compared to owning them, I prefer to be a bit more selective and store the albums locally. Either I like an album or I don't. That's why the free version of Spotify is great. I can listen to the album for free and make up my mind about it.
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Old 26th October 2019, 05:59 PM   #135
sq225917 is offline sq225917  United Kingdom
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The benefit of spread tow carbons is the reduced volume of resin in the crossover edge between warp and weft, this reduces mass/ increases stiffness.
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Old 26th October 2019, 08:22 PM   #136
5th element is offline 5th element  United Kingdom
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Quote:
Originally Posted by augerpro View Post
I always hear this, but no one has ever shown this to be the case. Seems a simple thing to test with multitone measurements. I won't say I've never seen a subharmonic, but it's been pretty rare, low level, and discreet. My second objection is that considering how rare HD audio is, how would one even energize this breakup with the Redbook CD cutoff being lower than the breakup?
I agree I don't see it as a problem. You don't need high frequencies to excite the issue just the frequencies that trigger the harmonics but the level of the IMD products produced is going to be below the threshold of audibility.

In theory it is a problem but in reality it's not. Unless the tweeters motor is very poorly designed. Still, from a purely academic point of view, I'd like the harmonics not to be there.
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Old 26th October 2019, 09:04 PM   #137
augerpro is offline augerpro  United States
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I agree I don't see it as a problem. You don't need high frequencies to excite the issue just the frequencies that trigger the harmonics but the level of the IMD products produced is going to be below the threshold of audibility.

In theory it is a problem but in reality it's not. Unless the tweeters motor is very poorly designed. Still, from a purely academic point of view, I'd like the harmonics not to be there.
Take a look at briskly's paper above. I'm not through it yet, but very interesting so far. We could use it to construct a test protocol and next time I take my measurement rig out I could do some experiments.
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Old 26th October 2019, 09:41 PM   #138
ErnieM is offline ErnieM  United States
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From the Beyma paper it looks like a much bigger problem in compression drivers. Careful design and use of Beryllium dome/polymer surround probably solves most of those particular issues. Doesn't change the fundamental flaws inherent in compression drivers at high power levels. Must be why they developed their version of the AMT shortly after.

I somewhat understand where Geddes is coming from when he says these are not issues in well designed home systems. Quality drivers of any type used below their limits are pretty well behaved. Just becomes a more complex task with higher spl.
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Old 27th October 2019, 03:35 AM   #139
eriksquires is offline eriksquires  United States
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Mundorf's AMT is also an amazing performer when it comes to power handling and lack of compression.
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Old 27th October 2019, 05:38 PM   #140
racingpht is offline racingpht  Canada
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Response curves have improved... new data (i.e. more representative response curves) will be available next month, I hope.
Hi USXX,

Sorry a bit off topic.. I also saw different curves between SB15NAC30 and SB15NBAC30 (the 700hz bump), are they just measurement artifacts/data revisions or there's driver design changes?

Thanks in advance,
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