Question BK Monolith DF how much it can take?


Standard Member
Hi everybody!

I know the question is about quite old subwoofer but I think that there is still users who use BK Monolith.
I bought second hand Mono DF(base model with no subsonic filter and dust cup on element, so I think its the older one) and I love it, but I am bit paranoid of breaking it(and now even more paranoid after Transformer 2 intro scene nasty pop at -25db).

Normally when we watch movie I had receiver somewhere around -30db .. -25db, but how much it really can take?
Of course it depends of how the audio of the film is mixed but I like to hear some examples from people who own or have owned mono that how hot you guys have ran it while watching movies.

Gain is set about half past 10 on Monos amp and on receiver LFE is set -2db if I remember right, I also have Antimode coupled with Mono and Antimodes subsonic filter is On.
I have read those old Mono threads, but there is so much messages about you guys waiting for delivery guy to bring their Mono to home so it's hard to find info about those listening levels which are "safe" and which not.


And thanks for superb forum!


Well-known Member
Honestly your best bet is to phone BK themselves if you have a question in relation to what it should be able to handle. Probably ask to speak to Tom as he has been very helpful in providing info to both myself and others. I am sure if you explain what happened he can likely give you the cause.

For me I have had no issue listening to movies at volume levels of -7 or -8 for some Disney soundtracks, probably a little lower for others, maybe -10 to -12. Your Mono shouldn't be breaking a sweat at -25db for MOST films. That's on a Denon receiver though, on my previous Yamaha then it would have been around -15 for most films.

I'm pretty sure a Monolith should be good under most situations till much closer to reference volumes and probably reference volume assuming your room isn't gigantic. Not that I have ever had mine at reference volume. I once accidentally had the receiver at -2 or 3 I think at the first battle scene in Master & Commander. The initial bit of the scene is whisper quiet so I assumed I had the volume too low. Once the first cannon fired the output from the Monoliths was truly truly scary. The Monoliths were fine at that volume as in they didn't exhibit any unwanted noises / pops. I've never had the guts to turn the volume up that high on anything ever again but I do know of several people who would listen to films at that volume on their Monoliths pretty much all the time.

Some film soundtracks do have exceptionally loud / low bass sections that have been known to kill off the occasional ported sub however, the Monolith also suffering from this on occasion from what I recall. Certainly a few on the old BK Monolith owners thread had to send back bits of their Monolith after listening to a few of the infamous scenes from certain movies.

I believe most if not all BK subwoofers do now include the ASP subsonic filter you mention to combat this to a large degree but obviously yours doesn't have this so it probably does make sense to be a little careful with regards to the volume on films that do have very "hot" bass included in the soundtrack. I think that the Antimode subsonic filter is around 12.5hz? And the port tuning of your Monolith will be around 17 or 18hz meaning that there is definitely a bit of a gap between the protection of the Antimode and the frequency at which your driver may begin to act as though it is in "free air".

Honestly if your Monolith is incapable of playing much closer to reference than minus 25db for the vast majority of films then is it really doing the job you bought it for? Again, I'm sure Tom will be able to advise on the best way to fully enjoy your Monolith whilst not taking unnecessary risks. He may even be able to test out that section of the film and let you know if he thinks there could be an issue. I don't personally have it so not too much I can say in relation to it specifically and mine may not exhibit an issue anyway if the ASP does block the troublesome frequency.

Good luck in resolving your issue. Hopefully it's nothing too serious.


Standard Member
I think it is not nothing serious, I think there is just something wrong with that movie intro scene or its too hot and too low for mono.
Room where our home theater set is, is 4,5m x 3,5m so I dont think its that gigantic.
Maybe I have to just crank it up from receiver and stop worrying about breaking mono since the levels you told are way beyond what I have ever used when watching movies.
I have read about those movies with subsonic bass sections and pay attention when watching those titles.


Well-known Member

It sounds like you are doing everything right then IMO and being careful when watching films that may have very "hot" bass sections.

Generally your Mono should really be absolutely fine at more or less anything you throw at it even at fairly bonkers SPL's!

If you are fairly handy you could phone Tom at BK and ask for a quote on having the ASP added to your amplifier plate. It may not be possible if it is a very old model but you might be able to just send in your amp plate and get it returned once the amendment has been done. Might stop you having to moderate the volume quite so much.

Anyway Enjoy! ;)

Tom @ PSA

Well-known Member
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Double check with BK but you should be able to add an external highpass filter to the sub signal upstream of the sub too. Not sure what the pricing is there but in the USA they range anywhere from $50 on up for the active models that are user adjustable. There's also passive in line devices for like 20 bucks.

Tom V.

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