QotD: Should I Buy Super Tweeters?
As you delve deeper into the hobby that is home theater and high-end audio, you’ll start to plumb some of the dark depths. You’ll hear whispers of devices and additions that will take your home theater or two-channel system to the next level. Some of these things will sound reasonable, others not so much. High-end speaker cables, aftermarket power cords, and more will turn up. Most are audiophile lies. But what about super tweeters? They are just tweeters that play higher than your normal tweeters. Can these bring your audio system to a new level? Should you buy super tweeters?
Answer: No. Like, all of the no. As much no as you can handle and then a little more.
What are Super Tweeters
A super tweeter is (usually) an aftermarket box that contains a tweeter that plays primarily above 20kHz. It is said to give your system a more “airy” sound. The idea is that there are harmonics up there that are present in the original music that need to be reproduced in order for the content to sound as lifelike as possible. There is a small problem: The majority of what a super tweeter adds is above the human range of hearing.
Audible Frequency Range
The audible frequency range is between 20Hz and 20,000Hz (or 20kHz). This is a well-known and researched fact. No one really disputes that. If you see someone claim they can hear above 20kHz, ask them how they tested that. Usually they used headphones and invariably those headphones weren’t of the highest quality. If they heard something above 20kHz (and they likely did), it is because the headphones (or whatever playback equipment they were using) were distorting. They were hearing the distortion and not the test tone.
On top of that, we lose our hearing as we age. Ever been to a concert and had your ears ringing after? That was your ears telling you that you just damaged your hearing. Are you above 20 years old? You’ve likely got age-related hearing loss (called presbycusis). No, don’t argue with me, talk to the researchers. And that age-related hearing loss? Occurs primarily in the high frequencies. So, of the 20Hz-20kHz audible range of sound, you are probably already missing some of the top frequencies. Sorry. I am too.
But What About Subwoofers?!?
“But…but…” You stammer. “You are constantly on about how we need bass lower than 20Hz! What about that smart guy!”
Yeah, so that is a different animal. See, you probably stopped hearing the lowest notes before you got to 20Hz. But you can feel them. That’s the difference between high and low frequencies. As frequencies get too high to hear, you just stop hearing them. That’s why you don’t “hear” your microwave sending out microwave or radio waves or Wi-Fi. They are all around you, but you can’t hear them because they are too high. Even if you pay close attention and are in a very quiet room, you won’t ‘hear” or somehow sense that someone nearby is connecting to the Wi-fi.
Bass is different. When you get to the lowest audible frequencies, and slightly lower, you may not be able to hear the sound. But you can feel it. That rumble that seems to vibrate your spinal fluid when you are at the movie theaters? That is sound that is too low to hear but that you can still feel. That’s why we recommend subwoofers that play lower than the human hearing range. Because they actually do something.
We often talk about how subwoofers are omnidirectional. That is because the bass waves are very, very long. The converse is true. The higher the frequency, the more directional the sound. Off-axis response is something we test in speakers not because of the woofers, but because of the tweeter design. This is why you see special waveguides on tweeters but never on woofers. Because bass doesn’t need to be directed. Treble does.
Super tweeters are playing even higher than a normal tweeter. This makes them highly directional. So, even if they did play sounds that you can hear (many start at around 8kHz, right where age-related hearing loss begins to get really pronounced), you’d have to have them pointed nearly straight at your head. That means that only one person sitting in one specific spot (with their head in a vice) would be able to enjoy them. In the best-case scenario, buying super tweeters is a waste of money.
Should You Buy Super Tweeters
Obviously, no. They don’t add anything that your current speaker shouldn’t be able to do by themselves. If you are worried about needing super tweeters, you should take a look at your current speakers. Can they play cleanly to 20kHz? Most speakers can. And for the price of many of the super tweeters on the market, you could buy a more capable pair of speakers that can play up to 20kHz.