Apr 1 Podcast #472: Crossover Frequency
We got a Twitter question from a listener about how to set the Crossover Frequency for his speakers and subwoofer, so we thought it might be worth while to explain the concept for everyone. For some this may be review, but if you’ve struggled with crossover, or have just left it set at the default because you didn’t know what to do with it, this is for you.
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Crossover Frequency
We got a Twitter question from a listener about how to set the Crossover Frequency for his speakers and subwoofer, so we thought it might be worth while to explain the concept for everyone. For some this may be review, but if you’ve struggled with crossover, or have just left it set at the default because you didn’t know what to do with it, this is for you.
For a really simplified definition, you can think of Crossover Frequency as a cutoff point. Anything below the crossover is sent to the subwoofer, anything above the crossover is sent to your speakers. This makes sense because your sub is intended to handle all the really low stuff and your speakers are meant to get the middle and high range sounds.
How to Set It
Setting the right crossover requires a little bit of research. The THX standard for Select and Ultra2 systems is 80Hz, and this tends to be the default for a lot of processors and receivers. But just because it’s the THX standard or the default doesn’t make it the best for your setup. After all, the first thing you do with a new TV is change the default picture mode away from vivid or dynamic, right?
Your research involves finding the specs on your main left and right speakers in your theater. The manufacturer should tell you how low they can actually reproduce sound. Anything below that can be sent to them by your receiver, but they won’t reproduce it, so you won’t hear it. If your speakers only go down to 100Hz, leaving the crossover at 80Hz means that you’re missing the entire 80-100Hz frequency range whenever you watch a movie, watch TV or listen to music. It’s like having a black dot somewhere on your screen - a part of the picture you just can’t see.
Get it Just Right - For You
If all you get in your spec sheet is the lower limit of the range, you can assume the speaker will go down that far, but probably not very efficiently. At some point above the lower limit the sound will begin to roll off, so you actually want to set the crossover above that bottom point. We tend to recommend setting it 10Hz above the lower limit of the speaker. Of course that’s your starting point. Use your ears to adjust from there.
Some manufacturers will list a different value, a effective lower limit value. For example, Polk lists the “Lower -3dB Limit” for their speakers. They’ve taken the guess work out of finding the roll off point. That value is essentially saying that although the speaker can go lower, below this point you’ll start to have diminishing returns. When you see a value like that in the spec sheet, use it as your starting crossover point.
A Real World Example
Our Twitter listener’s speakers were the Polk RM 75’s. They have a frequency response range from 95Hz to 24kHz. In most cases you’d start with the crossover at 105Hz (if your processor allows that, you might need to compromise and use 100Hz instead). However, Polk went the extra step of listing the Lower -3dB Limit, which is actually all the way up at 130Hz. So in this case, if your receiver will let you, you want to set the crossover at 130Hz. Otherwise you’ll get that big hole in the sound from 80Hz or 100Hz up to about 130Hz
Other Things to Ponder
You’ll want to keep in mind that the higher the frequencies go on your sub, the more directional the sound gets. Instead of just being the bass that rumbles in your chest, the subwoofer actually becomes like a speaker. This can produce sound issues you haven’t had before and may require you move the sub to find a better spot. In some cases the issue introduced, like standing waves and reflections, can be worse than missing some frequencies in the 100Hz/110Hz area. Again, let your ears decide.
Also, when they master content for 5.1 they tend to assume you’ll be using 5 satellite speakers and a subwoofer. In most cases they actually master the LFE content at 120Hz. Some receivers may have a setting for the LFE Filter or LPF (Low Pass Filter). This is not the same as the Crossover frequency and in most cases you’ll want to leave this at 120Hz. Since LFE content is never sent to the speakers, you won’t get a double bump on this stuff, it will only ever be played back on the sub, regardless of where your speakers crossover.
Reader Comments (21)
Going to miss you guys. Thanks for the ride! Best luck to both of you.
Kooly
Kooly, you know what today's date is right?
April fool joke, right?
I thought about it after I posted. Wow!!
I hate going on the internet today
I am hoping it was an April fool joke. Love the show guys. We don't know if them telling us this was an April fools joke wasn't actually the joke? Only next week will tell.
If you had listened to the whole Podcast, you would know that they are definitely done.
Thanks for a great 6 years guys, we have all grown old with you!
Thanks for all the great shows. My home theater wouldn't be what it is without you guys.
NOOOOOOOOOO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Please, let this be an April Fool's joke!!
I hope this is an April Fools joke!! If not, I appreciate all the work you guys put into the podcast. Best of luck with everything.
Good one guys! LOL
You got me!!
Oh!! You guys got me!!! Whew thank God it was just a joke. :P
When Ara tweeted " Recording our last show :-( " I was like "whaaa??!?" because it was still March 31st!
Then he was totally twitter silent - which is what actually tipped me off that it was an early April Fool's joke ;)
So you had me going, Ara! You honestly did. But I knew there was no way you wouldn't have responded to at least a few of the concerned tweets that I'm sure you got, so I figured something was up and then I figured out the setup :D
Happy it was just an April Fools joke!
You really had me going, never saw it coming. Thanks for laugh.
Didn't have me fooled for one second. I seem to remember you did this some years ago when April 1 appeared as a Tuesday podcast..
Keep up the good work though..
C'mon guys, you're better than the old, way played-out "we're quitting" joke. I was rolling my eyes all through this episode.
I'd just like to say you guys really suck for the April fools joke. When you said this was your last show I was so confused and distracted I ended up getting on the wrong train home. I am a long time listener and I felt like I was losing two good friends. Love the show, you guys rock. The recap on crossover frequencies was great, I'd like to hear more stuff like that. Ya got me!
I just listened (4/7) to episode 472. You guys got me! I was sad all the way right up until you admitted it was an April Fool's joke. Excellent. This was my year to fall for April Fool's jokes.
Great show, guys. :)
New to this podcast, had downloaded about 10 shows and was listening to them randomly as I commuted, definitely a new fan and enjoying the podcast, great stuff....and then this little gem starts and you guys announce its all ended and I am listening to the last podcast...but I have no clue what date you recorded this show and I fall hard...wow I was actually really disappointed to find a great podcast and its over, you had me big time, glad its a joke and your continuing the show!