Should I swap my DF sub for FF as it’s shaking my old house too much?

maxbrooker

Active Member
Searched other threads for advice, but I’m still non the wiser as there are conflicting opinions and my situation is perhaps more unique.

My cinema is on the 3rd floor of my 150 year old house. It’s a big room, 7m x 7m and I’m currently using a BK Monolith plus which being downward firing is really shaking the floor and travelling down to the ground floor. The top floor is constructed using a thin layer of concrete mixed with horse hair, floated on laths which in turn is suspended over supporting timbers and beams. The floor is carpeted on top of rubber underlay. All the walls are brick built, dry lined, insulated and plaster-boarded throughout.

i don’t have my sub up particularly high as my partner complains that the house rattles and shakes and they can hear it all the way down to the ground floor. We have a small 2 storey cottage attached to the back of the house which i don’t think is too badly effected, but i worry that they can maybe hear some of the bass coming through, although they have never complained or commented on it.

I don’t have the sub isolated from the floor, it just sits on the plastic feet that were supplied with it. The BK goes very low and you can really feel the bass, albeit slightly boomy.

So as a solution I’m thinking maybe 2 smaller forward firing subs placed within the front L&R sound stage. My aim is to try and improve the tightness of the bass and moving the air forwards towards the listening position, rather than through the floor and all the way downstairs? I’ve not looked at specific brands yet, but budget can be up to £2k.

Or should I be looking to decouple the BK from the floor somehow? Some recommendations involve a slab or isolation platform?

Any advice appreciated.
 

Gasp3621

Distinguished Member
Granite slab / slab of concrete (thick and heavy) was quite popular choice back in the days for DF Mono and XXLS400 what i remember here. It has helped many regarding stuff vibrating/rattiling on room etc. This is cheap thing to try for sure, but i don´t think it will remove the issue completely as you are listening to certain level (quite loud i assume) the bass will be heard below always.

20190222_130912-jpg.1122103



You can turn your Mono as FF and test it what difference it makes. So like below lay it on side.

s1510-and-monolith_small-jpg.1263942
 

maxbrooker

Active Member
thanks, I think I might have an old slab or two lying around so no harm in trying it.

I don’t listen at high volumes as I’m not allowed to, so I’m not anywhere near reference levels anyway. I think with the house being so old, it is “flexible” and it transmits sound more easily throughout the structure, although I’m not a structural engineer, so that assumption could be entirely wrong.
 

Ultrasonic

Well-known Member
Ha! Reading the OP I was thinking of suggesting turning your existing sub on its side so you could see what difference it would make. What I wasn't expecting was to then scroll down to see @Gasp3621 had posted one of my own photos to make exactly this point :laugh:.
 

Gasp3621

Distinguished Member
thanks, I think I might have an old slab or two lying around so no harm in trying it.

I don’t listen at high volumes as I’m not allowed to, so I’m not anywhere near reference levels anyway. I think with the house being so old, it is “flexible” and it transmits sound more easily throughout the structure, although I’m not a structural engineer, so that assumption could be entirely wrong.

Definitely try it out and also do another test with the subwoofer turned like the picture shows you. Then you have FF sub isolated from floor. I love testing stuff like this which doesn´t cost money.. Hope there would be cheaper solution, although i get if you also have a little "fever" for new toys. And the benefits for dual subwoofers are there aswell.. But first thing first try those two things.
 

Conrad

Moderator
thanks, I think I might have an old slab or two lying around so no harm in trying it.

I don’t listen at high volumes as I’m not allowed to, so I’m not anywhere near reference levels anyway. I think with the house being so old, it is “flexible” and it transmits sound more easily throughout the structure, although I’m not a structural engineer, so that assumption could be entirely wrong.
Certainly being on a suspended floor allows for much more tactile response in room than a concrete floor would. The vibrations can travel through the joists and it can end up feeling like the whole room is shaking. Some people pay a lot of money for that experience!
 

maxbrooker

Active Member
Thanks for all the tips guys. So I just quickly tried the sub on its side and isolated and the results were really disappointing. I would say I lost about 2/3 of the LFE so it just shows how well it was coupled with the floor and producing masses of LFE. I’m going to play around with the levels and positioning and see if I can improve on it. Like you say @Gasp3621 its fun trying these things out.

Quick question, are downward firing subs only a really designed for such use, or are they really not very different to FF designs?
 

MI55ION

Distinguished Member
Thanks for all the tips guys. So I just quickly tried the sub on its side and isolated and the results were really disappointing. I would say I lost about 2/3 of the LFE so it just shows how well it was coupled with the floor and producing masses of LFE.

That's interesting, never thought it'd make that much of a difference.

Edit: Did you take it out of a corner or away from walls by any chance?
 
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Ultrasonic

Well-known Member
Quick question, are downward firing subs only a really designed for such use, or are they really not very different to FF designs?
The latter. Compare FF and DF Monoliths on the BK website as an example.
 

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