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Sub Freq Response confusion Studio Monitors
Old 1 week ago
  #1
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Sub Freq Response confusion

TLDR: bought a sub, it's rated down to 22hz. Why's it dropping out at 40hz?

so I bought a sub for my studio, a Yamaha HS8S, it's rated down to 22hz. I got it more because I'm just a fan of bass and to extend the range of my synths, and less for mixing and so forth.

My confusion is if my sub is rated down to 22hz then why is it dropping out just under 40hz? Prerecorded music sounds tight, heavy and quite awe inspiring combined with my 8" M-Audio BX8 D2's. But then I tested a single pure sine wave on my synth and yeah.... it's dropping out way higher than I expected.

I learn as I go so probly just needing someone with more experience to help me out.

I've set up pretty well already with acoustic treatments and bass traps, monitor positions are about as good as I can do in my 16.5 x10.5 studio space, I'm in here sideways but little I can do about that. I have the Sub under the desk and slightly to the left, I'll be moving it to center in next few days but that requires a pretty serious desk mod.


posting a room layout, for some reason the image won't insert so here's a link
Room Layout
Old 1 week ago
  #2
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Let's start with the basics:
It is rated to 22Hz at -10dB. That is, once again, -10dB. Anything below -3dB borders on useless for a measurement of linearity. So you were kind of duped by those numbers.

On top of that, it is a ported subwoofer which means the slope of drop off will be fourth order (-24dB/octave). Just the way it works -- the port is tuned to a frequency which gives a bump and then a sharp drop off. If you do the math from a -10dB drop off at 22Hz, you can see you'll be in the mid-40Hz range for when that slope kicks in and starts rolling off the bass. Sharply. (A sealed sub would roll off at second order (12dB/octave))

And then finally, the room is a major influence. if you want more bass, put the sub in a corner. Don't put it in the center because that will put a massive dip in its response..

So TLDR: it's math, physics, getting fooled/not reading close enough to manufacturer specs, and you'll make it worse if you move the sub to the center.
Also, sub frequencies are omni-directional so no need to move it to the center other than hurting your frequency response. Humans have a hard time localising sub frequencies (has to do with the space between our ear drums due to our head and the size of wavelengths.)

Last edited by pentagon; 1 week ago at 08:31 AM..
Old 1 week ago
  #3
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so it's my fault, thanks for that! I'll try not to be a dumbass in the future then

it's center of my desk, not center of my room.

I put the sub in the corner already I can definitely tell where the sound is coming from to the point of it being annoying.
Old 1 week ago
  #4
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[OP deleted the request for where I got the spec info from in post #3 ; why they deleted that request, I have no idea but that is why the link follows if anyone is looking for the actual specs for frequency response]

HS Series - Specs - Yamaha - United States

If you can tell the location, most likely you have it turned up too much. Probably trying to compensate for the roll off you weren’t expecting.

Last edited by pentagon; 1 week ago at 08:34 AM.. Reason: added reason for link since OP asked and then hid the request
Old 1 week ago
  #5
Quote:
Originally Posted by pentagon View Post
HS Series - Specs - Yamaha - United States

If you can tell the location, most likely you have it turned up too much. Probably trying to compensate for the roll off you weren’t expecting.
This or the crossover frequency is too high for that setup. Either way I recommend getting REW (free) and getting familiar. Another option that isn't as accurate but works in a pinch is to place the subwoofer in your listening position and walk around the room until the low frequencies sound or feel best to you. Put the subwoofer there and it should sound similar at your listening point. The again, it might not. Rooms play a lot of tricks with low frequencies.
Old 1 week ago
  #6
One other thing:
Is there a polarity switch or phase knob? If so, try switching it. It will shift the interaction between the mains and the sub at the crossover range. Depending on room placement, that can really help.
Old 1 week ago
  #7
Re subwoofer placement - I've had my Genelec sub placed center of desk for 18 years. About 2 feet from the wall and roughly the same distance from my ears as the stereo pair. It works great in my room 12.5 x 25 ft. That's not to say it will work great in all cases, just to say it CAN work, and it's better to experiment than to apply blanket rules.

Playing sine tone sweeps can help identify peaks and dips in the response.

Also, low frequencies aren't as omnidirectional as is often claimed. Depending on the room and the crossover frequency. That's one reason why mastering rooms often have stereo subs or full range towers.

Best of luck with it!
Old 1 week ago
  #8
The directionality of a frequency depends on the enclosure and the baffle, not the crossover. In any studio subwoofer the baffle is much too small to allow anything other than omnidirectional transmission.
That doesn't mean you can't locate a sound source within the room, but the source is still omnidirectional.
Old 1 week ago
  #9
Quote:
Originally Posted by Jeremiah Sheets View Post
That doesn't mean you can't locate a sound source within the room, but the source is still omnidirectional.
That's right. Thanks for parsing the language and making that distinction!
Old 1 week ago
  #10
For sure. Low frequencies do wild things.
Old 1 week ago
  #11
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Quote:
Originally Posted by Trakworx View Post
Re subwoofer placement - I've had my Genelec sub placed center of desk for 18 years. About 2 feet from the wall and roughly the same distance from my ears as the stereo pair. It works great in my room 12.5 x 25 ft. That's not to say it will work great in all cases, just to say it CAN work, and it's better to experiment than to apply blanket rules.
Unless "center of desk" is not also center between two boundaries walls, you are having your sub put energy into a node and for that frequency (and its harmonics), creating larger dips and peaks.

Science doesn't care if you believe this or not. That's how sound waves work. Hard boundary walls impose nodes to the wave and the center will be the half wavelength node.

Luckily, the OP mentioned she is not situated centered between her walls (which will be compromise on the stereo image but that's a different issue -- lots of people have to compromise due to room layouts) so centering to her desk does not mean centering to the walls.
Old 1 week ago
  #12
Quote:
Originally Posted by pentagon View Post
Unless "center of desk" is not also center between two boundaries walls, you are having your sub put energy into a node and for that frequency (and its harmonics), creating larger dips and peaks.

Science doesn't care if you believe this or not. That's how sound waves work. Hard boundary walls impose nodes to the wave and the center will be the half wavelength node.

Luckily, the OP mentioned she is not situated centered between her walls (which will be compromise on the stereo image but that's a different issue -- lots of people have to compromise due to room layouts) so centering to her desk does not mean centering to the walls.
In my case it is also centered between the L and R walls.

I'm not disputing the science. Just reporting that I'm getting good results with this setup. I have a RTA and calibrated mic to shoot the room with. I've tested it thoroughly and it's pretty darned flat. Tens of thousands of tracks successfully mastered in my room.

With 12.5ft room width I believe I should have a problem at 90Hz and/or 180Hz according to the science. But I don't. Go figure. Maybe putting energy into a node is just the right thing in some cases?

I don't think she said whether or not her desk is centered between the side walls. She said "not center of my room" which can be interpreted differently...

Anyway, I don't want to argue, just here to encourage her to experiment and test. How can that hurt?
Old 1 week ago
  #13
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Quote:
Originally Posted by Trakworx View Post
Anyway, I don't want to argue, just here to encourage her to experiment and test. How can that hurt?
Since there is no "pain" involved it can't hurt. But it is a waste of time and uses a sub inefficiently.

Going by your dimensions, and if you are centered between the 12.5ft walls, your problem frequency is 90Hz and if you cross near or below that, you've had no issues for that reason. Still doesn't make it the best placement for the sub but it mitigates its impact on linearity.
Old 1 week ago
  #14
Come to think of it, I did crush my toe when moving speakers, so there could be a lot of pain involved!

Yeah, maybe I lucked out with my room dimensions combined with the 85Hz crossover frequency. I'll go with that explanation. Whatever, it works!
Old 1 week ago
  #15
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Quote:
Originally Posted by Michelle911 View Post
so it's my fault, thanks for that! I'll try not to be a dumbass in the future then

it's center of my desk, not center of my room.

I put the sub in the corner already I can definitely tell where the sound is coming from to the point of it being annoying.
It's also possible you can't hear 22 hz, I can't, but I can hear down to 27hz.
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