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Multi-Way Conventional loudspeakers with crossovers

Introduction to designing crossovers without measurement
Introduction to designing crossovers without measurement
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Old 21st May 2013, 02:33 AM   #151
Jay is offline Jay  Indonesia
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Quote:
Originally Posted by JackNZ View Post
The thing is that some records just don't sound good.
The better your speakers are, the more you will hear it.
So this can become a bit of a problem.
Does this happen to ALL "better" speakers?

My current speaker is very transparent. Actually it is part of the design objective. I wanted it to be the best at any price at its size category. In terms of its transparency, I think I have only heard one speaker having the same signature, it was a Martin Logan. But I don't think I want to keep this design

Or may be I want to blend specific features to get a good cross breed

But I still don't understand what is happening scientifically. I cannot buy that it is just like an amplifier with ultra low THD, where the output will be just similar like the input. Imo, speaker design is not as simple as that
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Old 21st May 2013, 05:44 AM   #152
JackNZ is offline JackNZ  New Zealand
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It is simple if you want to talk science.
Flat frequencie response on axys. Yes.
Flat energy response, means as even as possible off axys response.
Then very important: no phase jumps at transitions between drivers.
All this is allready not that easy to achieve.
If you have that, it should allready sound not too bad. But you have just started.
Doppler distortion is very audible because it actually changes the pitch of the record. Comes from one driver reproducing a too large part of the spectrum.
Same is also a problem if you want the driver to follow the waveforms of the recorded programm. If the driver is not reproducing vaweforms correctly, it will loose important texture and detail especially overtones and change harmonic content to the bad. So it is going to "not sound good" because it will introduce small amounts of disharmonic overtones. That can spoil a good record.
Sort out all those things and you will enjoy listening for hours.
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Old 21st May 2013, 06:25 AM   #153
Jay is offline Jay  Indonesia
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Originally Posted by JackNZ View Post
Doppler distortion is very audible because it actually changes the pitch of the record.
How do you describe this doppler distortion sound-wise? I mean, can you explain what it is sound like? I know about pitch, but I think there is more to it?

Quote:
Originally Posted by JackNZ View Post
Sort out all those things and you will enjoy listening for hours.
My experience cannot confirm that unfortunately.

There are many high-end speakers out there. And there has been nobody who can sort these things out?
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Old 21st May 2013, 07:37 AM   #154
JackNZ is offline JackNZ  New Zealand
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Hi end is about making money.
It is not about sorting out every problem.
Hi end has to look good. Sorry to say that. A speaker designed a 100% following
The rules will not look spectacular.
Doppler effect in music will let high midrange frequencies ho up and down in pitch
quite fast and so will the harmonics. The harmonics will then not anymore be harmonic to all the music. Hard to explane. Just when it is not happening you will notice time between the notes. A certain precision and air between everything.
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Old 21st May 2013, 08:28 AM   #155
Jay is offline Jay  Indonesia
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Originally Posted by JackNZ View Post
Doppler effect in music will let high midrange frequencies ho up and down in pitch quite fast and so will the harmonics. The harmonics will then not anymore be harmonic to all the music.
I don't understand about the harmonics go up and down. I agree that there is a possibility that a "phase distortion" plays the most critical role in high end speakers' problems. But as I can see it, speaker design (or issues) is not so simple. Science so far cannot prove the importance of doppler distortion in speaker. There are too many parameters that can affect sound quality.

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Originally Posted by JackNZ View Post
Hard to explane. Just when it is not happening you will notice time between the notes. A certain precision and air between everything.
I think I have noticed/heard this many times with high end speakers and my own (it is not rare at all). The questions are, am I experiencing the same thing? Is it the sound of no doppler distortion?

Many times ago I wrote in a thread about my observation of cone movement (I can tell the speaker design perfection from the cone movement).

Because the cone must produce or move in different frequencies, you will notice the small vibration to produce HF and big vibration to produce LF. The best sound was associated with a well controlled cone movement. It should (almost) always vibrate, no abrupt stops or such things, and changes are smooth.

To do the above we need almost everything:
(1) The cone must be stiff and light so it can vibrate along with LF vibration
(2) There should be a perfect compliance or suspension, from the driver itself (Qms/spider/surround/etc)
(3) There should be a perfect compliance or suspension, from the air behind the cone (Vas/enclosure design/enclosure type)
(4) The crossover effect is usually very noticeable (visually with the cone movement and sound-wise) in the use of LCR trap, especially in the mid band.

I think this explains why sealed enclosure tends to be always enjoyable, not because of the transient (which is also true) but because there is no issue with this "certain" thing that I associate with phase, may be the doppler distortion you are talking about.
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Old 21st May 2013, 09:49 AM   #156
JackNZ is offline JackNZ  New Zealand
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Hey Jay, you can not see frequencies.
You can visually distinguish about 25 movings per second.
You will not "see" midrange frequencies move.
Doppler is clearly changing pitch up and down by the movement of the bass speaker and is interfering with the midrange and is therefore changing the colour of the sound in a very important part of the spectrum.
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Old 21st May 2013, 04:49 PM   #157
AllenB is offline AllenB  Australia
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Quote:
Originally Posted by JackNZ View Post
What happens to the sound when our DIY crossover messes with the phase response of my speaker and gives me crazy coverage patterns?
I don't see how messing with the phase response can affect coverage patterns (unless you're referring to vertical lobing?). This is a function of the relative levels between drivers and the resultant acoustic characteristic.
Quote:
Originally Posted by JackNZ View Post
The thing is that some records just don't sound good.
The better your speakers are, the more you will hear it.
This is an often reported phenomena. I'm not sure I agree with it.

Speaker issues are typically more of a problem than recording issues. I'll cite: The Animals, House of the Rising Sun as an example of a recording that includes gross overload. This overload is far greater than many of us would like to accept in a speaker and yet, is capable of sounding reasonable.

The problem may be acoustic. When a speaker cabinet is malfunctioning it may give itself away. Any sound energy which is allowing us to locate and 'see' the speaker is wayward energy, let alone up to no good.

This may also be an issue where a crossover (or equalisation in general) has been used incorrectly to fix a problem that cannot be fixed that way. The result is made tolerable, nothing more. A recording with response issues that may highlight this range of frequencies in question could re-introduce the problem.

Take the example of listening to an ordinary television in a room. No matter how it sounds, it is clear that you are sitting there listening to a television. If you recorded this, re-creating the illusion of sitting there through a set of speakers is difficult. With most systems you will not be convinced. If you use such a speaker/setup that can, then the recording will sound much better despite the fact that it may be a recording of a simple speaker from within a room, reproducing distorted program material. It may actually sound like the original situation (and that is what it is...good or bad. It will at least sound correct). This implies that the speaker isn't changing anything significant from the recording..

Faulty speakers may also make the acoustic mistake of sending a significantly different characteristic of the sound to different parts of the room, betraying the intended illusion.

Quote:
Originally Posted by JackNZ View Post
no phase jumps at transitions between drivers.
Are you referring to linear distortions or time domain distortions?

Perhaps you're referring to Group Delay?

GD is usually measured in milliseconds and refers to the rate of change in phase, just as when a speaker is measured from an increasing distance, the phase response will wrap.

Group delay has been demonstrated to have a specific threshhold of audibility.

Last edited by AllenB; 21st May 2013 at 05:03 PM.
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Old 21st May 2013, 05:36 PM   #158
AllenB is offline AllenB  Australia
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Quote:
Originally Posted by Jay View Post
But I still don't understand what is happening scientifically. I cannot buy that it is just like an amplifier with ultra low THD, where the output will be just similar like the input. Imo, speaker design is not as simple as that
The first thing to accept might be that speaker function (including some speaker issues) happens in three dimensions.

Quote:
Originally Posted by Jay View Post
I know about pitch, but I think there is more to it?
When two tones are reproduced together in the presence of non-linear dstortion, a sum and difference signal are created between the tones, as well as between their harmonic distortion components etc. This sum and difference are not harmonically related to the intended signal and don't fit.

Quote:
Originally Posted by Jay View Post
I agree that there is a possibility that a "phase distortion" plays the most critical role in high end speakers' problems.
Phase distortion is not necessarily a problem even when it is present. Of course there are limits.

Quote:
(2) There should be a perfect compliance or suspension, from the driver itself (Qms/spider/surround/etc)
This may make sense with stiff cones crossed at a low frequency. Otherwise the outer cone is just hanging there, with nothing to 'hold its hand' if something goes wrong.
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Old 21st May 2013, 08:10 PM   #159
JackNZ is offline JackNZ  New Zealand
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Quote:
Originally Posted by AllenB View Post
I don't see how messing with the phase response can affect coverage patterns (unless you're referring to vertical lobing?).
I am talking about lobe distortion. Yes. Drivers can also be arranged horizontally. Then your lobing takes place in the horizontal plane. If x-over frequencie is in the right relation to center-center distance between the drivers and the phase relation is good, nothing bad happens.
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Old 21st May 2013, 08:20 PM   #160
JackNZ is offline JackNZ  New Zealand
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Quote:
Originally Posted by AllenB;


Are you referring to linear distortions or time domain distortions?

Perhaps you're referring to Group Delay?

GD is usually measured in milliseconds and refers to the rate of change in phase, just as when a speaker is measured from an increasing distance, the phase response will wrap.

Group delay has been demonstrated to have a specific threshhold of audibility.
Same as my last posting. Group delay happens if you deploy steep x-over slopes,
which I believe should be avoided in the lower frequencie regions.
But phase wraps and I don't think we hear this as a problem.
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