subwoofer LPF setting

[olds1959special]

I'm trying to optimize my subwoofer settings after changing my speakers to Elac DBR62 (and applying a notch filter to compensate for placing them on a desk.)

Previously I thought I needed to lower the LPF to around 55 Hz, but now it sounds better at 100 Hz. Is there a right or wrong way to do this?

 

[Keith_W]

The best way is to take some measurements and decide which is better. Trying to tune a subwoofer subjectively is a fool's errand.

 

[olds1959special]

The best way is to take some measurements and decide which is better. Trying to tune a subwoofer subjectively is a fool's errand.

I couldn't make sense of the measurements since they both looked "flat". I will post my results here.

 

[Chrispy]

No hpf on the speakers? In any case, what you prefer is what you prefer....

 

[olds1959special]

I now run all my setups that use subwoofers (I have three) without using the LPF. I just turn it all the way up. I prefer the sound of the subwoofers playing full range but then using an HPF on the mains.

 

[Chrispy]

I now run all my setups that use subwoofers (I have three) without using the LPF. I just turn it all the way up. I prefer the sound of the subwoofers playing full range but then using an HPF on the mains.

Your gear doesn't have any sort of lpf for the sub preout or ?

 

[olds1959special]

Your gear doesn't have any sort of lpf for the sub preout or ?

The subs all have LPF filters and my MiniDSP can do that too, but I prefer not to use them.

 

[terryforsythe]

Previously I thought I needed to lower the LPF to around 55 Hz, but now it sounds better at 100 Hz. Is there a right or wrong way to do this?

The subs all have LPF filters and my MiniDSP can do that too, but I prefer not to use them.

Do what makes YOU happy. It is your system. Whichever is your preference, go with it, and enjoy the music.

 

[olds1959special]

Do what makes YOU happy. It is your system. Whichever is your preference, go with it, and enjoy the music.

Aiming for decently flat frequency response charts too when measuring with RTA.

 

[terryforsythe]

Aiming for decently flat frequency response charts too when measuring with RTA.

@Keith_W gave you valuable information, with which I concur.

As for me, I measure with REW, use data from REW to set time delays in my miniDSP to get my subwoofer time aligned with my speakers, then use Dirac Live to do room correction. That brings me satisfaction, and I enjoy the resulting performance. But, that does not mean it will bring you satisfaction and enjoyment. If you think it may, give it a try. If not, keep doing what you are doing.

 

[terryforsythe]

Also, I posted the following in another thread, and it may or may not give you insight to help you in your decisions. What I may have not made abudantly clear, though, is that for my Elac/Velodyne system I am using a miniDSP HTx for crossovers and DSP, which is not the case for the KEF/SVS system. Here is what I stated:

For what it may be worth, here has been my experience with two different systems that I have:

In my office, for which the area and volume are approximately 15.1m^2 and 56m^3, respectively, I have a pair of KEF LS60 active speakers and a SVS SB-1000 Pro subwoofer. (In that small room the LS60s really don't need a subwoofer, but I inherited it). The subwoofer is located about 0.5m to the right of the right speaker. Using the KEF's subwoofer output and the KEF mobile app's subwoofer control, I first tried crossing over a 80Hz, but I could hear the subwoofer's location and it degraded the imaging for me. I kept lowering the crossover frequency until I no longer could hear its location, ending up at 40Hz.

In my family room, for which the area and volume are approximately 60m^2 and 354m^3, respectively, and which is open to the kitchen and other areas of the house, I have a pair of Elac Uni-Fi Reference bookshelf speakers with active crossovers and an old Velodyne HGS-18 servo controlled subwoofer. The subwoofer is located in a cabinet under the staircase in the front right corner, 1m to 3m from the right speaker depending on where I place the speakers (I set them up optimally for my listening chair for serious listening, but otherwise place them near the front wall centered on either side of the TV). Using a miniDSP HTx for DSP, at a 100Hz crossover frequency with 8th order slopes I cannot audibly detect the subwoofer's location. Recently, I experimented with 4th order crossover slopes at a 90Hz crossover frequency and still did not audibly notice its location.

The setups are quite different and there probably isn't one parameter that explains the difference in subwoofer detectability. The SVS SB-1000 Pro has higher THD than the HGS-18 below 40Hz, but I doubt that explains the difference. Perhaps the crossover slope the KEF app is using isn't steep enough for use with higher crossover frequencies. Perhaps placement of my subwoofer in the corner in my family room also helps, but I don't know.

 

[krabapple]

regarding 'LPF' for subwoofers

FWIW: historical Dolby spec (DTS too, I think? ) is for LFE ('.1') channel bandwidth to be 120 Hz.
AVRs that have their own selectable 'LPF for LFE' setting, default to 120 Hz for that reason (my Denons offer a range from 80 Hz to 250 Hz)

If you do, in fact, send 120 Hz bandwidth LFE content to a subwoofer, without any other filtering, you run the risk of it being localizable.
But AIUI, setting 'LPF for LFE' lower, means that the LFE content above that, is simply gone -- it's not directed to any other channel. (Not brickwall gone, but steep slope gone)

Of course, subwoofers have their own built in low pass filter*- the adjustable dial on the back fo the sub...I think it typically goes up to ~250 Hz?

(This is all distinct from the application of bass management to the other channels, where the 'LPF' is often recommended to be set at 80 Hz)





*and if the sub has speaker-level outputs, high-pass on those, as well

 

[olds1959special]

Is it good to set the LPF on the sub 10 Hz higher than the mains to allow for better integration, due to the crossover slope?

 

[levimax]

Is it good to set the LPF on the sub 10 Hz higher than the mains to allow for better integration, due to the crossover slope?

Crossovers based on acoustic slopes (not electronic slopes) are considered best practice in most cases.

 

[olds1959special]

I have another question about the LPF setting. If I'm running my mains full-range and combining them with the subwoofers, how high can I set the LPF on the subwoofers? My full-range speakers play down to the same frequency but roll off more in the lows and I like a bass boost, so my approach is wanting to set the LPF a bit higher (80 - 120 Hz). (I measure but also try things without measuring and just listening.)

80 Hz sounded very good but I want to try 120 Hz to see if there's a bass boost without loss of quality.

EDIT: 120 Hz sounded bad but 100 Hz sounds better!

 

[levimax]

The scientific answer is use a proper crossover with mains high passed and subs low passed around 80 Hz based on your individual measurements. If you co-locate subs and mains you can go higher on the crossover as you don't have to worry about localization issues. For bass boost use DSP. For your setup with full range mains and low passed sub and high bass boost you are pretty much just going to have to do trial and error and use what sounds best to you.

 

[terryforsythe]

Is it good to set the LPF on the sub 10 Hz higher than the mains to allow for better integration, due to the crossover slope?

It depends. If you are crossing over in a region where the bass response of the speaker already is rolling off, it may help, but keep in mind that it may also through off your phase alignment. It is worth a try if you have the ability to also adjust time delay.

If using something like Dirac Live, it automatically adjusts numerous parameters. I read somewhere, I don't remember if it was in a technical note or other documentation, that overlapping the crossover frequencies can be beneficial if using Dirac Live to manage the speaker/woofer crossover. I tried it and the results were pretty good.

 

[terryforsythe]

The scientific answer is use a proper crossover with mains high passed and subs low passed around 80 Hz based on your individual measurements.

That may work sometimes, but sometimes it is not the best option. A lot has to do with the crossover slopes, the room, the specific speakers and subwoofer, etc.

In my office I have KEF LS60s. I inherited a SVS subwoofer, and figured I would give it a try, using the KEFs to manage the crossover frequency. I don't know what is the crossover slope they are using, but probably 2nd or 3rd order. Regardless, I initially set the crossover frequency to 80Hz. I could hear the subwoofer's location and it messed up the soundstage for me. I kept reducing the crossover frequency in 10Hz increments until I no longer could audibly detect the subwoofer's location. I ended up at 40Hz.

In my family room I have Elac bookshelf speakers (converted to be all active), a Velodyne subwoofer, and manage the DSP/crossovers with a miniDSP HTx. In that setup I can crossover at 100Hz using 8th order LR filters and I cannot detect the subwoofer's location. The soundstage is wonderful. I have even tried 4th order crossover slopes and it worked well in that system in that room.