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

@perkri 

Here's a good blog post explaining the differences.   You can also use a free simulator like XSim to experiment without actually building anything.

 

https://www.tubecad.com/2017/11/blog0402.htm

@erik_squires 

Caps and coils are fundamental to creating high and low pass filters. Here’s a post I wrote a long time ago that may help you, though it covers the more common parallel crossovers:

Thanks for those links, I've sometimes wondered how that stuff works :-)

@erik_squires 

 

Thanks for the link!

 

Been on that site a few times, but never in that section.

 

Ill be checking it out.

 

p

@erik_squires - one of the links mentions 1st order is “as good as it gets without going active filters and bi amping.”

Do you have opinions on:

  • Active as in DSP PEQs, FIR etc.
  • Active as in OP-Amp based crossovers?
  • other?

Hey @Holmz - Not sure teh link- / context of what you are referring to.

Personally for home use I am not religious about active vs. passive crossovers. Anyone who has used a subwoofers has already at least dabbled in active filtering.

The biggest technical superiority of active speakers is power efficiency, something you need most in large venues. At home, simplicity matters a great deal to me. My main speakers are custom built, passive crossovers.  I'm thinking of making a high end center, which would be 3-way, active. 

DSP vs. Analog - With any speaker you have to make a crossover which, when added to your speaker's response, sums to an ideal end-result.  DSP based solutions really are the easiest, and add the ability to time align the drivers.

I like my stereo.  Mytek DAC, Luxman Integrated, 2-way stand mounts.  For me to go fully active I'd give up a great deal and add complexity.  Not willing to make that trip from here. That doesn't mean I'm averse to the idea overall.