Subwoofer settings


The more I search the internet on this topic, the more confused I get. I want to know how to set the low pass filter on my subwoofers. A lot of places people says around 80 hz. On the other hand a lot of people says 70% lower than the lowest frequency the speakers can play. My speakers have a frequency range of 33hz-50khz(-6db), and a frequency response of 48hz-28khz (+/-3db). It also says “in-room typicl bass response 27 hz (-6db)”

I don´t know what this means. Now, I understand that the general advise is to use my ears and dial it in according to my liking, but I really think it would help to understand a little bit about the theory. Cause I don´t know where to start. And frankly, I don´t know if i trust my ears; I´m not very good at deciding if the changes I´m making are right or wrong. Maybe eventually I´ll get there. Please someone, nudge me in the right direction.

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The main purpose of a subwoofer is to extend the frequency range below that of your main speakers, not to add more bass in the range that they already cover. So looking at the manufacturer’s specifications for the low end of the range is the right starting point. It’s not an exact point, of course, as the low frequency output will roll off gradually, so a little overlap may be beneficial. That’s where dialling in the sub settings comes in, along with trying different locations around the room etc.

If you want to be more scientific about it, try using software such as REW to measure your room acoustics so that you can see what’s really going on.

Thanks for taking the time to answer me. Greatly appreciate it.

Out of the numbers I quoted from the manufacturer above, which one is my speakers low end? Is it 33 or 48?

Hey Erik, I went through the same pain but I would be basing (no pun intended) on the higher -3db figure as a starting point and then backing it off in a downward trend, so you will probably end up somewhere between the 48 and 33 figure, 40 at a guess.

Likewise I saw lots of start at 80Hz advice, but that seemed to be in the world of AV.

The below are the specs for the LS50 Metas that I first paired my KC62 subs with

47 Hz - 45 kHz (-6db) Frequency range
79 Hz - 28 kHz (-3db) Frequency response
26 Hz - Typical in room -6db

I think I ended up around the 55 Hz crossover point in my main room, Kef recommended I start at around 60Hz when I asked them.

Thanks! Ill try starting at 37 and listen my way upward 48 to try and decide what sounds best. Thanks a lot for the help!

47 Hz - 45 kHz (-6db) Frequency range
79 Hz - 28 kHz (-3db) Frequency response
26 Hz - Typical in room -6db

Can someone explain in very simple terms what these numbers mean?

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I will try and it is simplest to focus on the low frequencies since there was interest in a subwoofer.

79Hz (-3db) means that the sound output is reduced by 3db at 79Hz relative to the “mid band”. This a equates to an effective power reduction of 50%. 47Hz (-6db) means that the output is reduced by -6db at 47Hz relative to the “mid band”. This is a 75% reduction in power. These are almost certainly measurements done in an anechoic chamber. The “typical room” measurement implies that in a typical room the -6db point is lower (26Hz vs 47Hz) which presumably reflects the bass reinforcement provided by the room boundaries. I hope that helps.

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Thanks, I sort of understand although it’s hard to relate a minus decibel figure to actual volume.

It’s just relative, so whilst the Hz range is present it is reduced in volume compared to the other ranges. So maybe think of glasses of wine, all at the same quantity but then there is one, that whilst it does contain wine, it is a dribble in the bottom of the glass as compared to the other glasses.

So in effect whilst it can be measured its effect is reduced, this is what the sub will do, fill out the bottom end so that the wine glass is at the same level to the other glasses, and then bring more glasses filled to the same level.

Ok I’m not sure this is helping, but I am drinking wine and my glass is nearly at -6db compared to when I filled it.

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I’m afraid you’ve got a bit more work to do if you want to successfully integrate the sub. There’s plenty of online resources elsewhere if you do a Google search but’s here’s what do.

Decide on a location for the sub (online guides for this or just choose buy know it may not be the most effective location).
Ignore 80Hz.
Set phase as appropriate.
Choose a starting crossover freq in the range of 30Hz to 50Hz.
Set volume/gain that you like via listening experimentation.

Feel free to adjust how you like. There is no single solution!