Hi,
Random question, just bought a second hand B&W ASW CDM subwoofer, in nice condition.
Whilst going through the set up procedure, set the volume to 12, LPF switch out, phase to 0 etc all seemed fine. When I turn the sub on, it emits a very audible low end hiss (like white noise I suppose)
for starters its not connected to anything else at all, just the mains.
What could it be, cant be normal for sure.
I dont want to give the sub back, and I trust the guy when he says its been fine.
Something simple, or is the amp module possibly to blame.
Please help 😕
Random question, just bought a second hand B&W ASW CDM subwoofer, in nice condition.
Whilst going through the set up procedure, set the volume to 12, LPF switch out, phase to 0 etc all seemed fine. When I turn the sub on, it emits a very audible low end hiss (like white noise I suppose)
for starters its not connected to anything else at all, just the mains.
What could it be, cant be normal for sure.
I dont want to give the sub back, and I trust the guy when he says its been fine.
Something simple, or is the amp module possibly to blame.
Please help 😕
the hiss gets worse the louder I set the volume, I would expect a bit of hum maybe from the amp, but not hiss, its very strange indeed.
Does the tonality of the hiss change when you alter the crossover frequency knob (if it has one)?
What does it do if you fit a shorting plug to the input.
High gain amps will often HISS if there is nothing at the input, ie no shorting mechansim.
High gain amps will often HISS if there is nothing at the input, ie no shorting mechansim.
if i adjust the filter to about 45 hz it almost completely goes away, but with the LPF switch set to out (as in the AV amp doing all the x over) is hisses pretty loudly.
the tonality doesnt change no.
if I have the amp connected to the subwoofer out on the AV amp it still does it, you can hear it in the background of the film or track.
it does have both left and right phono inputs, I connect the sub out on av amp to the right.
But you don't have anything plugged into it, right? Just the mains cord?
If turning the lpf knob down eliminates it, it's probably not the amplifier as the amplifier section is in place after the filter and gain stage.
I'd try hooking up all the cables and see if it still does it. It might be picking up noise from something and hooking the cables up to it might cure it. Granted, it's a very small part of the connector that sticks out with no cable connected, however it might be just enough to pick something up.
Edit: Just saw your last post. That's strange.
Perhaps try setting the low pass on your AV receiver to it's highest setting (if it has a separate setting for low pass to sub and high pass to mains) and then trimming the crossover frequency using the knob on the sub if lowering that stops the noise.
If turning the lpf knob down eliminates it, it's probably not the amplifier as the amplifier section is in place after the filter and gain stage.
I'd try hooking up all the cables and see if it still does it. It might be picking up noise from something and hooking the cables up to it might cure it. Granted, it's a very small part of the connector that sticks out with no cable connected, however it might be just enough to pick something up.
Edit: Just saw your last post. That's strange.
Perhaps try setting the low pass on your AV receiver to it's highest setting (if it has a separate setting for low pass to sub and high pass to mains) and then trimming the crossover frequency using the knob on the sub if lowering that stops the noise.
will connect up once more, there are two inputs (left and right) and two outputs, and two links (whatever that is)
10 mins I will be back to report.
okay, even with a signal going through it, still hissing, loud enough to notice, put it that way.
thats great, I will do that tomorrow for sure.
must be something silly, as I have googled it all morning, with no luck tbh, so cant be that serious surely.
Not sure what that is, would have to see a pic to know for sure.
You might be stuck just setting the crossover in the receiver to it's highest spot, so long as that doesn't adjust your main channels too, like this:
Receiver low pass to sub set at 120 (or however high it goes)
Main channels high pass set to 60 or 80 or however.
Knob on sub set to 60 or 80 or however to match.
The amps do fail. As it is still working they may be able to offer a service deal.
thanks for that, I have submitted an email for the time being, see what happens.
I'm not sure about B&W but Arcam never seem to respond to e-mails because of the amount of junk mail that they receive.
just one thing, could it be input capacitors? just read somewhere that a chap had a similar issue (just found it) on his velodyne sub.
I was trying to drive you down the route of shorting the inputs. That will give you a clue as to where to start.
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