Most people who seriously sit down to listen, do so in reasonably similar relation to the speakers so that designing for a wide variety of circumstances is not impossible. I totally miss your point.
Phase alignment is Time alignment. When you align the acoustic centers, the phase of the two drivers at the crossover frequency crosses perfectly.
That's why i said earlier, Time alignment, Phase alignment, Phase Coherent are all the same. Once we accept this, then it's easier to understand how to time align drivers.
If not, then how do you know when your drivers are Time aligned. How do you know the acoustic centers are aligned.
It all depends on the listener. If you a casual listener, it makes no difference. However, if you are a serious audiophile, it is a huge difference. Some go to great lengths to get the best sound out of their systems, even hiring electricians to rewire their switchboard so that they have dedicated power lines to their hi-fi system.
Another example is if you are a recording engineer, having time-aligned speakers is an added advantage. There is an audible difference. It will help you do a better job.
If you are in the business of installing sound systems, you need to know about time alignment. Most of the time, it will not be about time aligning the HF to the LF drivers of the speakers itself. It has to do with speakers in different locations, minimizing comb filter effects and others. In the end, it's about making sure the sound is good. That's what the customers pay for. They are not interested in the technicalities. If the sound is bad, you won't get paid.
hahaha..... people buy things for a lot of reasons.
I know of some rich people that have high-end systems. Ever heard of Watt-Puppies for surrounds? No kidding.
Whether he can appreciate his hifi or not, nobody dares to question. The general opinion is it is a status symbol. To the rich, status is very important.
Oh, don't forget ego, vanity and hubris. I think they are even more important.
Some people are only happy if they pay through the nose for items.
Well if it is expensive it must be good !
In the UK we have Dyson who make amongst other things Hoovers.
They charge about £250 for a Hoover.
I can buy a none Dyson hoover in my local store for about £50.
Dyson do very well. They are based a lot on hype about their products being more powerful and leading edge. What they don't say is there are hundreds of failed and refurbed items on ebay.
Well if it is expensive it must be good !
In the UK we have Dyson who make amongst other things Hoovers.
They charge about £250 for a Hoover.
I can buy a none Dyson hoover in my local store for about £50.
Dyson do very well. They are based a lot on hype about their products being more powerful and leading edge. What they don't say is there are hundreds of failed and refurbed items on ebay.
I knew someone who worked for Dyson in design.
On their first Hoover people were unplugging them and getting a shock off the plug pins !
There was a capacitor filter across the mains input which stayed charged up on power off.
Easy fixed with a 1meg resistor across the filter but embarrassing for Dyson who had to fix them all.
On their first Hoover people were unplugging them and getting a shock off the plug pins !
There was a capacitor filter across the mains input which stayed charged up on power off.
Easy fixed with a 1meg resistor across the filter but embarrassing for Dyson who had to fix them all.
Time and phase are not the same thing. There is fundamental difference between Group Delay (time delay of signal amplitude) vs. Phase Delay. No technically trained person will accept "Time alignment, Phase alignment, Phase Coherent are all the same", period. The WiKi link Dissi quoted is a good one. Here is another on Group vs. Phase Delay.
You are over thinking it. I keep on saying it is at the crossover frequency. If the woofer and tweeter sounds arrive at the same time, there will be no phase distortion at the crossover. In order to do that, the acoustic centers of the drivers must be aligned. That's Time-alignment.
Group delay is an entirely different issue.
No problem to accept also your simplified spec. that time-alignment is: acoustic centers are at the same distance from the observer and phase match at the crossover frequency. But in practice with IIR filters, phase distortion will not be zero because phase distortion cannot exist at a single frequency. In addition, defining of acoustic center at particular (crossover) frequency is not trivial without group delay analysis.
I'm afraid that you are over simplifying and making own standards here.
I used to work with a guy that did vacuum repairs for a well known (australian) vacuum seller.
The tricks and lies in advertising is beyond what I'd expected.
And yes, dyson = bose. But there is still 'One born every minute'..
Back to topic
Yes, there are some that can spend to set up a properly designed and tuned listening room.
But those would have to be the tiny percentage.
So, what I'm trying to understand, or work out, is, that given the argument that many buyers will have different rooms, and these different rooms will affect a given speaker in different ways.
Is there any one area of speaker design that will help the speaker present a decent account of itself ?
I'm trying to understand the mechanics and ideals better as I'm slowly learning the basics myself.
And there's been a flurry on diy about such deeper topics.
The tricks and lies in advertising is beyond what I'd expected.
And yes, dyson = bose. But there is still 'One born every minute'..
Back to topic
Yes, there are some that can spend to set up a properly designed and tuned listening room.
But those would have to be the tiny percentage.
So, what I'm trying to understand, or work out, is, that given the argument that many buyers will have different rooms, and these different rooms will affect a given speaker in different ways.
Is there any one area of speaker design that will help the speaker present a decent account of itself ?
I'm trying to understand the mechanics and ideals better as I'm slowly learning the basics myself.
And there's been a flurry on diy about such deeper topics.
I don't particularly like this simplified explanation as all it does is confuse people even more.
Particularly this one:
Even designers like Troels make sure they have a time aligned design, even though he likes to use second order filters. Yet this is different from what Dunlavy tried to accomplish with his first order filters.
This difference between the two is easily seen in the STEP response of the speakers. Aside from the audible differences between these topologies, I don't think it's wise to say it's all the same.
Grimm Audio is an example of speakers that use DSP FIR filters to get similar results to Dunlavy, the FIR filters make up for their use of higher order filters. Here is a whitepaper of their LS1 speaker.
Just calling it all the same thing just does not work out that well.
We have enough problems as is with people that are convinced they use first order or second order filters without realising it's the actual acoustic slopes that count. How many just slap on a LR2, either in passive form, obtained from an online calculator or active where they just pick out the slope as a pré-set and think they are done.
I don't think we can dumb down the discussion without creating even bigger confusion.
Particularly this one:
Even designers like Troels make sure they have a time aligned design, even though he likes to use second order filters. Yet this is different from what Dunlavy tried to accomplish with his first order filters.
This difference between the two is easily seen in the STEP response of the speakers. Aside from the audible differences between these topologies, I don't think it's wise to say it's all the same.
Grimm Audio is an example of speakers that use DSP FIR filters to get similar results to Dunlavy, the FIR filters make up for their use of higher order filters. Here is a whitepaper of their LS1 speaker.
Just calling it all the same thing just does not work out that well.
We have enough problems as is with people that are convinced they use first order or second order filters without realising it's the actual acoustic slopes that count. How many just slap on a LR2, either in passive form, obtained from an online calculator or active where they just pick out the slope as a pré-set and think they are done.
I don't think we can dumb down the discussion without creating even bigger confusion.
Only one person has got the answer right so far. Time alignment is done by making sure the voice coils are aligned, usually done by angling the speaker baffle. Bang and Olufsen studied this in the 70's and it has nothing to do with phase alignment of the signal which is usually when the one speakers wires are connected the wrong way round.
Just imagine how awful the sound might be and often is when listening to an orchestra in a concert hall with all those out of phase and non-time aligned sound sources. This thread appears to be specifically about the crossover region, so there is a lot to be said for keeping it as narrow as possible.
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