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What is the right cross-over frequency using subwoofers (Monolith 15in) with Kef R11s on my NAD M33

bvhme

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Hey speaker folks!

I'm relatively unexperienced in setting up systems, however I've decided to upgrade mine last week. I've upgraded to a NAD M33, Kef R11 and have also bought 2 Monolith 15in subwoofers (last still in transit). With the black friday and some bargain hunting I've composed this awesome system and I'm soooooo excited.

I'm planning on using Dirac live to tune the speakers and subwoofers to work well together and with my (odd and large) room.

I do however have some questions that I could use your help with:

What would the right crossover frequency be to set on the M33.

I see the R11s have a THD of <0.3% 120Hz-20kHz. And the 15ins have a THD between 19.8 at 16Hz and 1.3% at 120Hz (manual says <1% 20-100hz). It is very clear that there needs cross-over well before the 120Hz, but there is a bit of an information gap here. The R11 go down to 30Hz (-6dB) and have a frequency response (±3dB) 46Hz - 28kHz. The M33 can be set in increments of 10 from 40Hz.

It would be awesome if Dirac could also create a suggested crossover frequency and set it, but sadly that doesn't happen, and it's also impossible not to set a crossover frequency.

I could make measurements, but I really have no idea what to measure, so any hints/guides would be more than valued.

Thanks :)
 
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abdo123

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Hey speaker folks!

I'm relatively unexperienced in setting up systems, however I've decided to upgrade mine last week. I've upgraded to a NAD M33, Kef R11 and have also bought 2 Monolith 15in subwoofers (last still in transit). With the black friday and some bargain hunting I've composed this awesome system and I'm soooooo excited.

I'm planning on using Dirac live to tune the speakers and subwoofers to work well together and with my (odd and large) room.

I do however have some questions that I could use your help with:

What would the right crossover frequency be to set on the M33.

I see the R11s have a THD of <0.3% 120Hz-20kHz. And the 15ins have a THD between 19.8 at 16Hz and 1.3% at 120Hz. It is very clear that there needs cross-over well before the 120Hz, but there is a bit of an information gap here. The R11 go down to 30Hz (-6dB) and have a frequency response (±3dB) 46Hz - 28kHz. The M33 can be set in increments of 10 from 40Hz.

It would be awesome if Dirac could also create a suggested crossover frequency and set it, but sadly that doesn't happen, and it's also impossible not to set a crossover frequency.

I could make measurements, but I really have no idea what to measure, so any hints/guides would be more than valued.

Thanks :)

Do you have an idea what type of crossover filter the NAD will use?

Type as in Linkwitz-Riley or a Butter worth
Or slope as in 12dB/octave or more .etc

Typically you want to measure the roll-off of your speaker. Luckily we have spinoramas for it already.
 
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bvhme

bvhme

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I can't for the life of me find the crossover filter, however I see some mentions of 6...12 etc, so that might be the, seemingly agressive, filer.
 

abdo123

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I can't for the life of me find the crossover filter, however I see some mentions of 6...12 etc, so that might be the, seemingly agressive, filer.
a search on google might help, other people might already have figured it out.

either way you would want to use the slopiest filter you can use (the highest number), The KEF R11 should have no problem really playing down to the crossover frequency all, but it would suffer horrendously at 20Hz for example, the lowest octave (20Hz-40Hz) is incredibly difficult to produce.

you want something like this happening

1638309130121.png


Not like this

1638309176243.png
 

Dal1as

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A lot depends on your room and how the subs and speakers interact. are you going to use REW? If so you can experiment and make sure for instance you don't have them crossed right at a ball room Null, etc.

I will say that if you listen at higher levels do not fall into the trap of crossing your mains too low. You have 2 good subs. Start at 80hz and let your mains deal with the higher mid bass.
 
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bvhme

bvhme

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Thanks again for the great help!

I used REW to measure the frequency whilst sliding the subs around the room. I learned that putting the sub in the listening position and measuring around the room didn't really work, so sliding the sub around it was.

Exploring REW I found the SPL and THD graphs, and I chose a compromise where the SPL was pretty flat whilst the THD was low (1.99% up to 200HD!!!)

I'm now crossing at 60Hz. The slope does seem very smooth on how it response.

I also got a null at 110, that I thought I could ignore. But Alas, that seems like an important frequency given some careful listening. So I'll be redoing it regardless.

I've got a Union-1 coming in so I can do some better measurements. I might come back with some more questions.

Thanks again!
 

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