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Subwoofer Basics
Old 10th December 2019
  #1
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Subwoofer Basics

I'm thinking of making some upgrades after the holidays, and am considering a subwoofer, since upgrading my monitors to something fuller range would cost far more. I'm using Dynaudio LYD7s, and am happy with them overall, but I'm hoping a sub could improve not only the low end extension, but overall quality by reducing the low end burden on the monitors. Is this how it works in reality?

Does adding a subwoofer (sealed) cause the monitors to behave like sealed speakers in their timing, assuming the crossover is at or above the port frequency? I've never used a sub, so I'm just making sure I get the general ideas right. How is the port frequency determined? The specs don't disclose it.

Also, the obvious first place I looked for a sub is the Dynaudio 9s, since it should ideally integrate (right?), but is it possible to use something cheaper with the same or better results?

What got me started on this was the experience of listening to my larger sealed speakers in the other (untreated!) room where my records and stereo live. The bass response on those Human 8" speakers is very tight, deep, and defined, and I hear a lot in my own rough mixes when I play them over there that just isn't as obvious in the treated studio room. So I'm looking to add both extension and improved tightness.
Old 10th December 2019
  #2
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tymish's Avatar
 

Unless you seal off the ports the time domain performance of your LYDs won't change. If you do seal them it's hard to say what effects positive or negative that will have. If you want the performance of sealed enclosure monitors it's best to buy a set designed that way. Nonetheless ,adding a sub will certainly gain you extension and heft below the free field cutoff of 55Hz of the LYD 7s if that's what you are looking for. Another thing that may gain you is smoother low end response by moving the bass driver to a different location in the room. A lot of time having the speaker at ear height also happens to be the midpoint of a room dimension which can excite modes.
Old 10th December 2019
  #3
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Originally Posted by tymish View Post
Unless you seal off the ports the time domain performance of your LYDs won't change. If you do seal them it's hard to say what effects positive or negative that will have. If you want the performance of sealed enclosure monitors it's best to buy a set designed that way. Nonetheless ,adding a sub will certainly gain you extension and heft below the free field cutoff of 55Hz of the LYD 7s if that's what you are looking for. Another thing that may gain you is smoother low end response by moving the bass driver to a different location in the room. A lot of time having the speaker at ear height also happens to be the midpoint of a room dimension which can excite modes.
Thanks. My room has high ceilings, so no problem there. I've tried a few different placements, and this one is good. I'm also on iso stands slightly tilted up to get the right listening height and avoid desk reflections.

The Dyn subwoofer has a highpass that can be set up to 80hz for the satellite speakers, so I'm wondering if that would essentially eliminate the port activity.
Old 10th December 2019
  #4
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forget about port (and possibly also frequency overlap): a sub will get you what you desribed above and additionally can help to even out room modes.
for optimum loading, put it in the front corner, not mid-wall (or if you do so, put the sub sideways, with the woofer as close as possible to the front wall)...
Old 10th December 2019
  #5
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Originally Posted by deedeeyeah View Post
forget about port (and possibly also frequency overlap): a sub will get you what you desribed above and additionally can help to even out room modes.
for optimum loading, put it in the front corner, not mid-wall (or if you do so, put the sub sideways, with the woofer as close as possible to the front wall)...
That is definitely counterintuitive, but I'll try it if I go this route. I had pictured it centered between the Lyds, either on the floor or on a shelf just above my head, but didn't think a corner would be a good idea!
Old 10th December 2019
  #6
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Quote:
Originally Posted by Disco1Disco2 View Post
That is definitely counterintuitive, but I'll try it if I go this route. I had pictured it centered between the Lyds, either on the floor or on a shelf just above my head, but didn't think a corner would be a good idea!
https://www.soundonsound.com/techniq...t-control-room
Old 10th December 2019
  #7
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Thanks. Good read.
Old 10th December 2019
  #8
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Yup, this all day. Typical home studio ceiling height is 8 feet. Monitors are usually at ear level which is almost dead in the middle. I happen to have a sealed monitor system with a sub. Right now low end response is pretty smooth from about 35 - 100. But I still have a dip around 120 and broad peak centered at 150. Trying to figure out my next step.
Old 10th December 2019
  #9
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Quote:
Originally Posted by tymish View Post
Yup, this all day. Typical home studio ceiling height is 8 feet. Monitors are usually at ear level which is almost dead in the middle. I happen to have a sealed monitor system with a sub. Right now low end response is pretty smooth from about 35 - 100. But I still have a dip around 120 and broad peak centered at 150. Trying to figure out my next step.
...the thing with subs is this: you need to look at walls nearby as they act as mirrors!

anything within a quarter of a wavelength of the frequency in question (say the x-over) is fine, anything above is rather bad - to illustrate: if you have a sub with an lpf/hi-cut/x-over at 100 hz and you position it at 1.75m from any wall (sides, floor or ceiling), sound bounces back with the phase at 180° off, resulting in maximum cancellation...

similar thing at work with the sub facing you: since subs emit sound almost omnidirectionally (the lower you go the less directional they get), you get sound bouncing back from the front wall with then is somewhat out of phase; turn the sub to the side and on the floir and you got coupling from the walls (front wall and floor), resulting in more output.

you can use phase cancellation to your advantage by positioning the speakers at a distance where the peak gets attenuated...

off topic: 35hz isn't very low for a sub - you're still missing out the lowest octave... (but you can check with your headphones)
Old 10th December 2019
  #10
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tymish's Avatar
 

Quote:
Originally Posted by deedeeyeah View Post
...the thing with subs is this: you need to look at walls nearby as they act as mirrors!

anything within a quarter of a wavelength of the frequency in question (say the x-over) is fine, anything above is rather bad - to illustrate: if you have a sub with an lpf/hi-cut/x-over at 100 hz and you position it at 1.75m from any wall (sides, floor or ceiling), sound bounces back with the phase at 180° off, resulting in maximum cancellation...

similar thing at work with the sub facing you: since subs emit sound almost omnidirectionally (the lower you go the less directional they get), you get sound bouncing back from the front wall with then is somewhat out of phase; turn the sub to the side and on the floir and you got coupling from the walls (front wall and floor), resulting in more output.

you can use phase cancellation to your advantage by positioning the speakers at a distance where the peak gets attenuated...

off topic: 35hz isn't very low for a sub - you're still missing out the lowest octave... (but you can check with your headphones)
It's a small sealed sub as well as the tops, not ported so it may not go as deep as a ported sub. Blue Sky Pro Desk. Very tight sounding though, for the music I do I'm not missing that last bit at the bottom but do check with cans. The system is hard crossed over at 80Hz, no option to change that. Much higher though and you can start hearing the directional bass where the subs are.

I have the sub at an angle now. For the most part it's doing pretty well considering it's a small basement in my home with low ceilings. The peak and dip between 100 - 200 are less than 10 dB either way.
Old 10th December 2019
  #11
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...that explains the poor fr (to some degree). imo hearing the lowest octave is indeed not always needed (but fun!) and i find dips/peaks of 10dB way beyond reasonable and no, you will not get directional cues from a sub even if it goes high up unless it's got insane port noise or distortion - but hey, whatever you like, is within budget and does the job...
Old 10th December 2019
  #12
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Quote:
Originally Posted by deedeeyeah View Post
...that explains the poor fr (to some degree). imo hearing the lowest octave is indeed not always needed (but fun!) and i find dips/peaks of 10dB way beyond reasonable and no, you will not get directional cues from a sub even if it goes high up unless it's got insane port noise or distortion - but hey, whatever you like, is within budget and does the job...
Well, it's what I have and have had for almost 20 years and no budget for new. Surprisingly good setup for the size and $$. Sub only has an 8 in. driver. I do like the time domain response of this system.

Yeah, the problems between 100 -200 are something I want to deal with but right now my studio is for my own fun so when I can I will. I don't have my measurements in front of me, I think it's more like 6 dB each way.

I start noticing sub location starting around 100 Hz. I can't imagine going any higher without causing imaging and phase issues. Have you had luck with higher settings?
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