Monolith Sub Buzzing with Denon 2300W

JeanLaCritique

Standard Member
Hello you knowledgeable folk.

So I have a bk monolith subwoofer and the constant buzz has become too distracting and I want to get to the bottom of it.

If the sub is powered on with no input cable connected then there is no buzzing. I'm using the 5m phono to phono cable that came with the monolith which has a red and blue phono on each end of the cable. I have plugged just the blue in to the back of the AVR and just the blue to the monolith, which I think is the correct setup.

Once the input cable is attached, If I turn the low level gain to around the 9 o'clock position then I can hear an electrical hum/buzz and once it gets to 12 o'clock it is pretty loud. I can hear it over quieter programs and if nothing is being played I end up having to get up and turn the sub off as it is distracting.

I don't know where I can make changes at this point, I assume it is something with my Denon? These are the only settings I can see to change the sub and what they are set as but changing any doesn't really stop that buzz from what I've tried:

Subwoofer Level Adjust is set to Off - I have tried this at -12dB with no difference.
Within Speakers/Test Tone the Sub is at 0.0dB
Crossovers are set to 80 Hz
Bass: Subwoofer Mode is LFE and LPF for LFE is 120Hz.

Any help or troubleshooting testing to attempt would be greatly appreciated!

-- Update during own troubleshooting: I just disconnected the phono cable from the back of the AVR but still plugged in to the Sub and the buzz got a lot louder. If I held the cable a certain way with my hands the buzzing stopped or at times lessened as I moved the cable or held it just so. Could this all be down to the cable? --
 
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Gasp3621

Distinguished Member
I would call to BK Elec and ask to speak with Tom Pearce. Describe the issue you just wrote and i´m fairly sure he can help you. In worse case scenario you just have to send the amp there and they fix it swapping some parts. Usually very cheap in the end what i have seen some 8-10year old BK subs being fixed by members. But call him tomorrow ASAP! He is best person to answer your issue really. Report back what he said and what is the next step.

Telephone: +44 (0)1702 527572
 

JeanLaCritique

Standard Member
I've dropped him an email, will see what is suggested.

I had a dig around in my box of cables and found a red/white/yellow composite that was probably from an old dvd player. When I hooked up the sub and amp using just the red cable surprisingly the hum was a lot quieter. I could turn the low gain around to about 2 o'clock before I could hear any buzz.

Now, I'm sure this cable is a piece of crap and not entirely suited to the task. But would this suggest a good quality replacement phono may be a good shout to try?
 

Tom @ PSA

Well-known Member
AVForums Sponsor
I just disconnected the phono cable from the back of the AVR but still plugged in to the Sub and the buzz got a lot louder. If I held the cable a certain way with my hands the buzzing stopped or at times lessened as I moved the cable or held it just so. Could this all be down to the cable? --

Definitely try a different cable. If you have any old composite (yellow) video cables in a box those work fine for subs as they have a decent amount of shielding.

Tom V.
 

roscopervis

Active Member
I too had a lot of hum from my Monolith (second hand from the bay) at 50hz which made me think it was related to the mains frequency.

What really helped me was using a RCA to XLR adapter and plugging the lead into the balanced XLR input - no hum, even at high gain.
Whether this was just mine and the RCA inputs are dodgy, I don’t know, but the cable is the same, just with that adapter. Worth a try.
 

JeanLaCritique

Standard Member
My cable arrived on Friday and sounds good, no buzz until around the same point as the composite - perhaps a bit further, but that's already plenty of bass! I may look at the XLR adapter if I really want complete silence. But as is, I'm a happy chap.

I took one of the head caps off the old cable and one of the copper threads at the end had completely disconnected from its housing. I was using the other of the pair at any rate, but it suggests the cable simply wasn't that good to start with or perhaps prone to failure.

Cheers with the troubleshooting peeps.
 

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