THE IMPORTANCE OF TIME DOMAIN RESPONSE MUST READ
Speaker designers ignore or downplay the importance of TIME. Why?
A high end speaker should be as accurate as possible and that means it should not only be optimized with regard to frequency response but time response.
Back in the 70’s and around that time, speaker engineers thought that a perfect speaker would be one that had a flat response. This idea has waxed and waned in popularity over the years and even now there is no consensus.
What the speaker engineers forgot to consider is Time response.
The time reponse of a speaker is how fast it starts and stops. A perfect speaker would have a perfect time response of 0. Since this is not possible, we must get as close to it as possible. The problem is speakers engineers have neglected this aspect of the design and so speakers over the last 40 years have not improved in this respect.
Time is such an important aspect of the sound we hear. We not only hear tone but also time. The brain can detect time differences of only a few microseconds. Experiments have shown that the start of each note is what we use to determine what instrument is producing that sound.
We must ensure that our crossovers do not smear the time response because it will be heard by our ears. Time inaccuracy is why high end speakers do not sound like real instruments.
Diffraction from the cabinet can also cause time smear. We need spherical cabinets not square boxes. Tweeters need to be time aligned in order to ensure that when the woofer stops so does the tweeter. When the woofer starts, so must the tweeter. The woofer itself has to have a Qts of ZERO to prevent time smear. Ports must not be used or else you will get ringing.
We need to make it mandatory for speaker companies to publish the time response of all their speakers so that consumers can easily compare and decide exactly what they want. Some may actually prefer a speaker that has a poorer time response and that is fine. The problem is, we cant decide unless we know what we are buying can we?
Unfortunately, 90% of speakers on the market, even high end speakers have ports. And they are also made of cheap wood, even though there must be better materials by now. Some materials ring more than others.
So dont be deceived folks. If you want better speakers, you will probably have to make them yourself because speaker manufacturers dont care about sound quality. They spend millions of dollars on anechoic chambers all so that they can get a flat response but they spend zero effort on better time domain response. We are being duped.
What is Time Domain Response? I thought the Motor assembly was the biggest part of how or why a speaker starts & stops. What is QTS? How do you get a QTS of zero and what would that do? How does 0 QTS prevent Time Smear? How do Ports Ring? Why are your own speakers made of wood and why are they ported? Kenji, You cannot accurately answer any of these questions. Please stop embarrassing yourself. Or are these things that only a Master Audiophile could know? |
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I explained that at the beginning of this topic. Time domain response is how fast the speaker responds.
Rubbish. The cabinet can sing along with the drive unit and smear the time no? That has nothing to do with motor assembly
The QTS is the Q of the driver. It is the total combined Q including electrical and mechanical.
It would mean that the woofer starts and stops when its told to. It woud not ring like a bell which when struck will continue to resonate.
Continuing with the bell analogy if you hold the bell when its struck it wont ring anymore. The speaker needs to start and stop exactly the same way the input signal does. Minimizing the time smear is a way to do this.
They ring when the air inside the wooden box vibrates at a certain frequency. However, like most things that vibrate, they unfortuntely do not stop immediately but can take time.
I have more than one speaker. But yes wood is used for one of them as a test cabinet. Wood would not be used for a reference design. I experiment with various types of technology. I use ports for the same reason everybody else does. In order to get more bass out of small cabinets. However I understand that this is a compromise and perfect speakers must not use them.
It is not enough to know how to tune or design a speaker in order to be a champion audiophile. Many speaker designers do not understand music. They obsess over measurements and dont know how to listen to their designs. This results in a poor outcome. So this should be a lesson to you. You thought you could tune my speakers without even seeing them. Custom tuning involves every aspect including the room. You had no idea what room I have you didnt even ask. Do you have a device to measure the polar response because that is also important. |
@ditusa The question was for Kenji.... he has emailed me at home many times and I can tell you that he does not have a fundamental understanding..... as you can see, read the answer he sent. |
@timlub feel free to correct me if you think I do not have a correct funamental understanding |
You stated that it tells us "how fast a speaker responds:. The motor of a speaker directly affects the speed in which a driver reacts. What you are call ing time domain response is in direct correlation to drivers alignment combined with each drivers natural rolloff and crossover components used. On QTS, you did quote the textbook response that qts is a summed combination os qms and qes, but you still show no understanding of what that means. Mechanical q can be affected by mass, electrical q affected by electrical transfer in the motor and induction of the coil. The combination QTS is a direct correlation of how this Zdriver will work in a sealed box vs a ported or vented. Any driver that has a qts below .4 ish will not go down in a sealed box and any driver with a qts below .25 or so will have a problem going down in any box. As QTS rises..... .3 to .4 do a very good job of being used in a ported or vented box, a QTS of .4 to .5 ride the line that can be used in ported or sealed and .5 and above will work well in a sealed box. Combine this with VAS, the drivers equivalent air pressure tells us what size of box this driver will work in.
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Why focus on the motor alone? it can be also due to the input signal current, the mass of the driver etc
The cabinet also rings. yes crossover circuitry can also cause ringing. So how do you stop it? Do you have any answers? |
You know Kenji, you are one person that I wish that i would have never responded to when contacted. I tried to help you, you tore me down, I still tried to help, you argued and now, you post that I don't know anything about your room or your boxes..... Ok, I am done with you..... You know, I can post our conversations that you sent to my home. I can tell others what drivers you use, that they are put in MDF with a flat front, that they are not countersunk that they are forward firing with no tow, that they are 7 to 8 ft apart, (you didn't want to measure) and are currently set up in a triangle..... No, your right, I didn't ask you anything about your current speakers or set up. Consider your email blocked from my home. |
Likewise. You misled me into thinking a design would be forthcoming, even giving me a deadline yet you then pulled out at the last minute after hours of discussion. Perhaps you realized that meeting the requirements of such a perfect audiophile like me was far more difficult than you first thought.
Of course they dont know what theyre doing. A speaker is supposed to reproduce the signal you give it. Yet all high end speakers sound and even measure differently. They cant all be right can they
Its not just about getting them to know how wrong they are. Its about getting them to design speakers correctly. Audiophiles spend millions of dollars on high end speakers. It is a multi million dollar industry. We deserve better quality. So I deserve my speakers to be accurate not only in tone but also in time. Until that happens we are stuck and the only solution is to make and tune our own speakers. Which is what you obviously realized when you did the SNR1. Do not buy fritz though. They are not very good.
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This is also a false accusation. I have designed speakers. But just as all speaker designers will not reveal their secrets, why should I? If you have spent years tuning a speaker why should you give away all your hardwork? Does Fritz tell us the values of the caps he uses in his designs so that others can copy his work? I dont think so. I have worked hard to be a champion and I will not help my competitors gain an advantage and put my status at risk. |
@kenjit How wold you define “right”?
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so you see @holmz the spectral decay ensure its oms at frequencies...... I dealt with this guy for a week everyday, he did not absorb a thing..... complete aggravation Kenji, you are confusing the X and Y axis with the L & V axis. |
What is oms? I do not think that we can apply an impulse to a system and get it to decay instantaneously unless we have zero output impedance, which a passive crossover sort of gets in the way of. The spectral decay is amplitude based in frequency versus time.
Lets assume that we have two speaker, both with 0 msec of decay. Are there other measurements that would inform us of whether one is better than the other? |
@kenjit said: "The time response of a speaker is how fast it starts and stops." I claim to know almost nothing about the subject, but isn't kenjit confusing time alignment of individual drivers in a multi driver design with the impulse response of an individual driver? And of course, as usual he frames it as a plot that "they" have cooked up to dupe us. Go home. |
@roxy54 thumbs up 👍👍 |
Maybe @roxy54 - or the air pressure response of a driver given an impulse of current or voltage… But the later assumes that the current is somehow not allowed to ring in the circuit from the mass of the driver and its motor through the cable to the amplifier. Hopefully @kenjit can clarify what he means, so we are not left guessing.
Then there is:
So it that a speaker, as in cabinet, driver… i.e. the whole enchilada? (where “speaker driver unit” is like an indivisible quanta fundamental element (i.e. unit) of what makes up an elemental speaker.) |
There are many sources of ringing within the speaker. The cabinet can ring, the driver can ring, the crossover parts can ring. We need to stop all ringing wherever it occurs. It needs to be able to reproduce a square wave |
Maybe let’s just ignore the ringing that may be happening long after the square wave’s fundamental period is over. Or we could take a step function, so we only have 1/2 of the square wave… and that makes it simpler to consider and we got rid of half of the square wave… and also got rid of a train of square waves.
What needs to reproduce a square wave?
What should the electrical square wave input look like in a plot? |
Kenjit, your entire history here from as far as I can remember has been throwing aspersions on speaker manufacturers, designers and DIYers with vague and unprovable statements and absolutely no specific example of how to do things better, or even what you’ve heard which sounds better or worse. Remember the month you spent arguing that there was no need to markup parts? Or the thread where you said you took apart a speaker and saw it had a bunch of parts in it you did not understand? Hilarious. I dare you to hold up a single specific example anyone else could replicate or go listen to as better or worse than what you are suggesting. Somehow you never do, you just show up talking trash, in this case such general trash you are denigrating speaker makers as a class in their entirety. |
Thanks @erik_squires . Well said. And if he cares about music and speakers so much. why will he not say what he listens to? |
Fritz doesn’t use capacitors in his crossovers. Once again kenidjit strikes out. He uses the acoustic reality series crossover. One of the reasons why his speakers measure so well, and how they provide an easy, and consistent load for the amplifier to see. Surprised you don’t know about this crossover, seeing as you are such a great speaker designer and superior audiophile.
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And how does that disprove my point? He does not publish his circuits online does he? So why should I reveal all my secrets? Every designer can only reveal so much.
Just take the damn thing out and use an active crossover.
How would that change anything? A scoffer like you would not believe me even if I did state what I listen to. |
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Sorry but I believe you misread his statements. Fritz doesn’t use caps in SERIES with the tweeter. He uses caps though. Fritz famously uses series crossovers, which are quite rare in our world. Still uses a cap but it is in parallel with the woofer (or something like that).
99% of all speakers I’ve ever seen or heard use parallel crossovers, which have first order components in series with the drivers. This includes famously time coherent speakers from Vandersteen and Thiel. Best,
Erik |
From what I understand, he uses the ARSXO, which he acknowledges (as is required because of the patent held, which was made open provided anyone who used it in a commercial venture credited the circuit/inventor) The classic version of this crossover has one resistor, two inductors and of course the drivers in a two way wired in series. I know there is a version of this crossover out there that includes a single capacitor, but that is not the circuit he links to in his description? If you know otherwise, please elaborate as I would be very curious to know more! And yes, more often than not, speakers use parallel crossovers. Much easier to tune a speaker that way. Each element can be isolated with greater ease. Change one thing in a series crossover, and you change more than one thing. Not as easy to isolate a problem. I’ve spent a fair amount of time over the past year or two trying to better understand the ARSXO, and have built several speakers using it. Have even managed to convert some diy friends after A/B comparisons using the ARSXO and the manufacturers crossover supplied, or, recommended crossover to be built. No capacitors, just those three parts.
But I would honestly be interested in learning more about Fritz and if/how he implements the caps.
Thanks!
p |
@perkri I’ve spoken to him a few times, he has my phone number and sometimes calls me out of the blue. My recollection from our discussions is that he’s never said he doesn’t use caps, but that because they are not in series with the tweeter he doesn’t have to use boutique caps the same way and can spend the bulk of the money on the drivers. On his site I found this line:
He isn’t saying no capacitor at all. :) He has _never_ said to me he doesn’t use caps. BTW, Fritz are some of the very few 2-way speakers I can always recommend unconditionally. PS - He's a super nice guy, feel free to call him and ask him if I'm mistaken. |
@kenjit All must come together as a nerdly whole! Stop 1. organize riot at Magico headquarters. Stop 2. Dairy Queen… we’ll deserve a tasty treat after all that rioting. |
Qts that is being referred to is a Thiele-Small parameter for damping of the speaker--a combination of the mechanical and electrical damping--with a lower number indicating higher damping. In a simple minded way, a lower number does reflect closer to instantaneous stopping of the driver after an impulse. But, that does not imply that a lower number is better. The parameter allows one to choose the right driver (primarily woofer) for the particular kind of speaker (sealed box, bass reflex open baffle, etc.) and to determine the particulars of the design being employed (volume/dimensions of the box, port dimensions, etc.) and so there is no one ideal value. Higher values are better in some applications. Pick too low a value and the speaker will lack bass, sound dead and overdamped. Unfortunately, as in previous postings, the OP has seized upon one thing as the magic bullet for perfect speaker design when there is no such thing. There is no one speaker in the whole world that everyone will agree on as sounding the best, much less any single approach to achieving a high performing design. |
One more thing, speaker/driver design involves balancing different performance parameters because there is no one design that optimizes all measures of performance. Even if one is shooting for a very low Qts (extreme damping), this will affect other parameters, such as Cms (compliance of the speaker--the stiffness and how easily it is to move the diaphragm) and therefore, also the Fs (the resonant frequency which determines at what frequency the driver will roll off). To achieve that high damping of a low Qts, the speaker will have to be very stiff, meaning it will also roll off at a high frequency, will require more power, and subjectively, it will sound dead and tuneless. |
For you to have competitors you would have to be a professional speaker maker. For you to attack other speaker makers without being willing to show example of your work and how your designs differ is simply crass. I know of no speaker manufacturer who wouldn’t immediately jump at the chance to highlight their technology or approach as a distinguishing feature. And I know of no speaker manufacturer whose products are so secret they don't advertise them. 🤣 |
The differences between speakers are small but exaggerated in order to gain an advantage. Secrets are few and far between. How would you know what design aspects are being kept secret if they are secret?
Some of the ways you could improve a speaker are obvious though. You could use thick braced HDF rather than thin unbraced MDF. It would only add a couple of hundred dollars at most to the cost yet the speaker manufacturers will not do it unless you pay tens of thousands of dollars for their top models. Custom tuning is another thing that is better than mass production. Those Fritz speakers you mention are mass produced. Their only unique selling point is their stupid series crossover. Whereas I would just take the damn thing out and go active anyway. Funny how if series crossovers are so wonderful only Fritz can successfully implement them dont you think? Its incumbent on the speaker companies to make improvements, not me. If these commercial speakers are so good, why were you forced to make your own? For exactly the same reasons I have mentioned. You wanted something customized and at a less exorbitant price. |
Thankyou for your support. |
