8800NL - high pitched noise

[mognog]

Then I guess all you can do is locate it where you can't hear it or partially cover the box (whilst keeping any air vents free) with some sort of sound proofing box/material or foam (for sale in most online stores).

Perhaps that's a money spinning project - making sound proof boxes for routers and the like.

Every cloud has a silver lining

[gatekeeper]

I think we all need to get realistic here. A piece of electronics designed to be an ADSL or VDSL router is not meant to produce irritating audible tones or other audible noises. I doubt very much whether the original specification for the Billion 8800NL ever specified that it should produce an audible noise during operation. Anyone who simply regards it as 'a feature of this model' is, frankly, being fatalistic and rather accepting. The fact that the product produces - or at least, appears to produce - unanticipated audible noises means, in my and most other professionals' books, that the product has failed in its overall purpose. The same principle would apply to any other piece of electronics, whether from Billion or some other company. I state this with some conviction, as I worked in the electronics industry for over 30 years as a professional, and I therefore know the difference between good and bad design.

The mere fact that an unknown number of 8800s may be producing this noise is therefore an indication of its 'less-than-perfect' design. It very much looks like inadequate attention was paid to the design stages of it, and doubtless the situation was made worse by Billion being in a rush to compete with other modem-router manufacturers to get the next model out of the door.

That said, I'm also of the view that Billion have demonstrated over the years that they can produce routers and modems of excellent performance. So, I can only hope that jrawle's and perhaps others' experiences in this regard are notified to Billion ASAP and that Billion takes the necessary steps with future models - including the newly-announced 8900 series - to ensure that this sort of thing doesn't happen again.

[gatekeeper]

Jrawle, Billion-fan et al,

I've been wondering whether that 8KHz tone is perhaps the frequency of a switching type power circuit in the brick adaptor. Maybe that's become a sort of de facto switching frequency? All the same, I notice that manufacturers of peripheral devices do now seem to favour switching power supplies, even for comparatively low power devices. In several ways, employing a switching type of power supply makes sense, as you can then make the power supply run more efficiently, with it wasting less power in heat. Also, at moderate power levels, you can put almost all of the required components inside the brick, and perhaps make do with just some simple filtering of the DC inside the router. However, when high-frequency switching is involved you have to use good filtering of the DC thus produced, ensuring that very little of that HF component gets through to the device itself via the DC. If the filtering isn't good enough, you could end up with all sorts of second-order effects. In some cases, the amplitude of the HF 'breakthrough' might increase with the amount of current drawn. This might, for example, explain why, in its unconnected state, the router seems not to be producing any noise, but as soon as an appreciable amount of additional current is drawn - by the sync'ing action and the status lights coming on - you start to hear it.

[mognog]

So would you think that a Ferrite bead (https://en.wikipedia.org/wiki/Ferrite_bead) on the power cable would perhaps help here?

[jrawle]

I would assume most power supplies are switch mode now. I just looked through a few in the Farnell catalogue, but the data sheets don't specify how they work or the switching frequency. I supposed if faced with this problem, you could try buying a replacement third party supply in the hope that its frequency is different and doesn't produce the same resonance.

I can't say I notice the noise since the router is in its proper home.

[gatekeeper]

mognog,

Re the suggestion about a ferrite bead, yes it might well help. Not sure if you're referring to a loosely-coupled ferrite bead, which you could possibly apply as an afterthought, or instead a fully wired-in inline ferrite-cored inductor. But either might do the trick.

Yes, an increasing number of peripheral devices use switching type brick power supplies. I've just bought a 7-port USB hub and that definitely uses a switching power supply, as it states so on the back of the brick. If you look through the images of aftermarket brick power units available on Amazon, you'll see that some of them do indeed have inline inductors. The power brick for my new USB hub doesn't have one. Yikes!

[gatekeeper]

Jrawle,

Yes I too have noticed that, in the vast majority of cases, an advert for a 5v or 12v power brick doesn't specify whether it's a linear type of unit or is instead a switching type. But if it is a switching type it'll sometimes say so on the top or the back of the brick. I've briefly looked at the brick used with my 8800NL and there's no indication there, unfortunately.

[hermit]

Thought I would add to this thread as gatekeeper pointed out that my experiences of my recently acquired 7800dxl mirror the issue here with the 8800nl. I have posted this information in the 7800 forum, but to summarise: last week i purchased a 7800dxl for my ADSL line. Very pleased with the performance, particularly being able to force a 3dB SNR setting from the exchange which has nearly doubled my line speed. However, the modem was producing a very high pitched whine which was driving me loopy. I could hear it right across a 6m room. After being advised by billion_fan that this was not a characteristic of the model, I requested a replacement from the online retailer which arrived today. I uploaded the config file and changed power supply and adsl cable. Well the new modem also produces a high pitched whine, however it is less intrusive than the first model. I can only pick it up about 1 metre from the device. This may be due to frequency i suppose. Again it is only present whilst there is a stable ADSL connection and also when negotiating an ADSL connection. Unfortunately I am suffering a bit of tinnitus at the moment, hopefully not from the previous model . I have yet to decide on a course of action.

hermit

[gatekeeper]

Hermit,

I used to own and use a Bipac 7800 (the wired-only model) and that certainly didn't whine. Currently, I use an 8800NL, but only in ADSL mode. That too doesn't whine. Your 7800DXL might well consume more power than my old 7800, though. And jrawle reckons his noise is there, on the 8800NL, only in VDSL mode, which may well be again a situation where it consumes more power.

In your shoes I'd be trying to experiment with different means of providing a clean and stable 12v to the router. But other than replacing the supplied power brick with one from a different source, experimenting wouldn't be easy to do because of the special DC connector.

The new power brick that arrived today: is it exactly like the original one? What does it say on its label? And I'll ask the question again: what happens to the noise if you adjust the target SNR upward on your 7800DXL, to bring the sync speed down?

[WaypointCharlie]

!! FIXED !!

I've just bought a used 8800NL off eBay. It works fine, except I notice it has a high-pitched whistle which starts once the router has booted. That's how I discovered this thread.

It's not the power supply (I've swapped them). The noise is coming from within the unit. To my tone-deaf ear it's about 10kHz and very unpleasant in a quiet room.

As I bought it off eBay it's not going to be covered by the warranty. So I took it apart:- Undo the four screws (one under the warranty label) and carefully prise it apart, using a long fingernail (or the wife's credit card) to unclip the tabs located in the middle of each edge. I noted that the circuit board was tested in September 2014, so in theory it's still within warranty.

I discovered the culprit - choke coil L18, located near the antenna. It appears to be supported solely by its connecting wires and it's possibly those wires that are vibrating. A slight repositioning of the coil immediately fixed the problem. I don't suppose there are any hazardous voltages generated by the circuit but to be safe I used an insulated stick to move the coil when it was powered up and making a noise. As far as I can tell, the router still works properly (I'm using it to post this) and the WiFi level looks fine.

If you don't mind having a go, and invalidating any warranty, it really is a very simple fix.

8800NL_fix.jpg