2. speakers
  3. 180448-17271

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.

kenjit
kenjit OP
1,771 posts
 

What is Time Domain Response?

I explained that at the beginning of this topic. Time domain response is how fast the speaker responds. 

I thought the Motor assembly was the biggest part of how or why a speaker starts & stops.

Rubbish. The cabinet can sing along with the drive unit and smear the time no? That has nothing to do with motor assembly

What is QTS?

The QTS is the Q of the driver. It is the total combined Q including electrical and mechanical. 

How do you get a QTS of zero and what would that do?

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.

How does zero QTS prevent Time Smear?

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.

How do Ports Ring?

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.

Why are your own speakers made of wood and why are they ported?

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.

Or are these things that only a Master Audiophile could know?

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. 

timlub
2,039 posts
 

@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.  

kenjit OP
1,771 posts
 

@timlub feel free to correct me if you think I do not have a correct funamental understanding

timlub
2,039 posts
 

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.  

 

kenjit OP
1,771 posts
 

Why focus on the motor alone? it can be also due to the input signal current, the mass of the driver etc

What you are calling time domain response is in direct correlation to drivers alignment combined with each drivers natural rolloff and crossover components used.  

The cabinet also rings. yes crossover circuitry can also cause ringing. So how do you stop it? Do you have any answers?

More to discover