Difference between Butterworth and Linkwitz Riley? (MiniDSP)

[Deleted member 48726]

Hi

Tinkering with my new MiniDSP 2x4 HD a couple of days ago, experimenting by ear with different filters when EQ was already applied, I thought the LR 48 dB/oct for crossover frequency sounded the best but ran out of time that day and left it "as is" with the LR 48 dB/oct.

From what I can muster on the interwebz, the LR is an integrated butterworth filter and I can also see it has - 6dB at crossover frequency.

Are there any "rule of thumb" to which filter to use for high pass and low pass and are there anything you really want to avoid?

Thanks

 

[My adventures in stereo]

Try measuring with different filters and see what gives you the best curve & if it matches your perception

 

[pma]

LR is better for crossover filters, the reasons described in a simple form here:

Linkwitz–Riley filter - Wikipedia

en.wikipedia.org

 

[DonH56]

Linkwitz-Riley is a cascaded Butterworth topology that matches amplitude in the crossover region. I would just stick with that. The -6 dB actually leads to ideally flat response through the crossover region. See e.g. https://en.wikipedia.org/wiki/Linkwitz–Riley_filter

Edit: @pma just beat me to it!

 

[anotherhobby]

I prefer LR for the reasons mentioned above. Also, when being used between subs and mains, I prefer the sound of a 24dB/oct crossover vs 12 or 48.

 

[Tangband]

Hi

Tinkering with my new MiniDSP 2x4 HD a couple of days ago, experimenting by ear with different filters when EQ was already applied, I thought the LR 48 dB/oct for crossover frequency sounded the best but ran out of time that day and left it "as is" with the LR 48 dB/oct.

From what I can muster on the interwebz, the LR is an integrated butterworth filter and I can also see it has - 6dB at crossover frequency.

Are there any "rule of thumb" to which filter to use for high pass and low pass and are there anything you really want to avoid?

Thanks

Can only agree what others already told you.

In a threeway - Crossing below about 300 Hz, there might be some benefits with odd orders crossovers ( for example 18 dB ) - you might get a better power response in the room in this way. Its always the resulting acoustical side of the slopes that matters - so even If you select 4th order 24dB/oct in the minidsp it might differ slightly acoustically, depending on many things, mostly because drivers have a very unflat frequency response when put on a baffle.

You have to use measurements to really know what is happening.

 

[Deleted member 48726]

Thanks for the replies, guys.

It is crossover from mains to sub. 80 Hz right now. the LR 48dB/oct sounds the "cleanest" or "dry" to my ears. LR 24 dB/oct. sounds more imprecise and Butterworth filters even more so. Of course I will do measurements in due time to find out why.

I am just wondering if it's a general no-go to use this steep crossover because, well it's the steepest in the settings and I tend to think that maybe it's not what most people use.. ?

The answer seems to be that it depends on the room and the response from the main speakers.

 

[pma]

Personally, I prefer Bessel-Thomson filters.

 

[mdsimon2]

Can only agree what others already told you.

Crossing below about 300 Hz, there might be some benefits with odd orders crossovers ( for example 18 dB ) - you might get a better power response in the room in this way. Its always the resulting acoustical side of the slopes that matters - so even If you select 4th order 24dB/oct in the minidsp it might differ slightly acoustically, depending on many things, mostly because drivers have a very unflat frequency response when put on a baffle.

You have to use measurements to really know what is happening.

x2

IMO actually considering the natural acoustic response of your drivers will have far more impact than the difference between BW and LR.

Michael

 

[Deleted member 48726]

Personally, I prefer Bessel-Thomson filters.

Why?

 

[Tangband]

Thanks for the replies, guys.

It is crossover from mains to sub. 80 Hz right now. the LR 48dB/oct sounds the "cleanest" or "dry" to my ears. LR 24 dB/oct. sounds more imprecise and Butterworth filters even more so. Of course I will do measurements in due time to find out why.

I am just wondering if it's a general no-go to use this steep crossover because, well it's the steepest in the settings and I tend to think that maybe it's not what most people use.. ?

The answer seems to be that it depends on the room and the response from the main speakers.

Genelec uses 48dB/oct acoustical slopes in the dsp crossover for SAM monitors when using SAM subwoofers. So, no - there is not a no-go for this. At least 36 dB/oct is needed with only one subwoofer in my opinion.

If you use two bass reinforcement subwoofers, you can sometimes get away with a simple 12 dB/oct inverted crossover, - If the subwoofers are in stereo and set very near each L/R main speaker. This can sound very good.

If you study the acoustical natural roll off of a closed box, you can see that such a main speaker roll off below the box resonance frequency with approx 12 dB/oct . This is why THX crossovers constructed to work well with closed box main speakers are 24/12 dB electrical = 24/24 acoustical.

In real life- its terrible complicated because of the room gain in a normal room.