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kwlinca
2006-01-23, 09:58
I am trying to track down the cause of wide swings in signal strength. When my SB3 is working optimally, signal strength is ~85-90% and sounds great. The problem is, at start-up (power on), the SB3 sometimes struggles to connect, and when this occurs, it may only connect at a signal strength of 20-30%. The SB3 will play at this signal strength, but there is underlying digital hash that sounds like AM radio static.

Some particulars: Windows XP, software version 6.2.2, Buffalo wireless g router to Buffalo g repeater plugged directly to the SB3. The SB3 is put in stand-by (red power button) between uses and the computer is turned off at night.

I have tried power disconnects of the SB3, router, repeater and computer, but don't seem to be able to find something that clears up the problem consistently. Suggestions?

Thanks!

Mark Lanctot
2006-01-23, 10:13
You're experiencing wireless interference,
although it's very, very unusual that you can hear
audible artifacts in what is a data stream.

Do you have a laptop with a wireless connection?
Then download NetStumber:
http://www.netstumbler.com/downloads/ and
investigate your router's signal strength.

Try changing channels on your router. NetStumbler
also makes it easy to test which wireless channel
has the highest strength. The only
non-overlapping channels are 1, 6 and 11, although
4 and 8 have also been suggested by one vendor and
8 works best for me.

But it is very unusual that you'll actually be
able to hear an interference artifact and this
seems to suggest some EMI that's getting through
the power line or perhaps the interconnects - this
massive interference would occur at the same time
as the signal strength drop, making the signal
strength drop appear to be the cause when it may
not be, but rather a side-effect of the real
cause. Even a cheap surge protector may help as
some of them have rudimentary power conditioning,
or you could try a $5 ferrite core available at
Radio Shack to snap onto your power cord
(apparently this worked well for one SB user and
also increased his signal strength).

See
http://forums.slimdevices.com/showthread.php?t=20272

I'm not a big believer in expensive power
conditioning to improve sound, but if it doesn't
cost much it's worth a try IMHO.

kwlinca wrote:
> I am trying to track down the cause of wide swings
in signal strength.
> When my SB3 is working optimally, signal strength is
~85-90% and sounds
> great. The problem is, at start-up (power on), the
SB3 sometimes
> struggles to connect, and when this occurs, it may
only connect at a
> signal strength of 20-30%. The SB3 will play at
this signal strength,
> but there is underlying digital hash that sounds
like AM radio static.
>
> Some particulars: Windows XP, software version
6.2.2, Buffalo wireless
> g router to Buffalo g repeater plugged directly to
the SB3. The SB3 is
> put in stand-by (red power button) between uses and
the computer is
> turned off at night.
>
> I have tried power disconnects of the SB3, router,
repeater and
> computer, but don't seem to be able to find
something that clears up
> the problem consistently. Suggestions?
>
> Thanks!
>
>

--
___________________________________


Mark Lanctot
___________________________________

kwlinca
2006-01-23, 11:06
Thank you for the suggestion. I will look into changing the channel. It may indeed be interference from a neighbor's wireless network. I changed all the 2.4 GHz phones in the house to 5.8 GHz. On occasion, the microwave in the kitchen (30 ft away) can produce a temporary glitch in connection, but it reconnects back to high signal strength. Once the unit is locked into higher signal strength, it doesn't drop out of it; it is only on reconnections when the computer has been turned off at some point (like at night).

As to local EMI/RF interference, all components are connected to a Panamax 5100 power conditioner/filter/surge suppressor. The "static" that I hear is different from 60 cycle hum; I get a small amount of that even when using a linear power supply (to replace the stock switcher). The 60 cycle hum can be eliminated entirely by switching to battery power (I have a fulled modded Red Wine Audio SB3), but this does not eliminate the "static" from low signal strength.

snarlydwarf
2006-01-23, 11:49
As to local EMI/RF interference, all components are connected to a Panamax 5100 power conditioner/filter/surge suppressor. The "static" that I hear is different from 60 cycle hum; I get a small amount of that even when using a linear power supply (to replace the stock switcher). The 60 cycle hum can be eliminated entirely by switching to battery power (I have a fulled modded Red Wine Audio SB3), but this does not eliminate the "static" from low signal strength.

Well that should cover most of the noise on the power input line, but I'd suspect it's being introduced at some point after the DAC (either the internal one or an external one).

A corrupt bit or three in an mp3 will sound... horrible. Not staticky, it will be painful. (Never mind that TCP checksums and such should make the possibility of bit corruption between the SB and the server be incredibly rare -- as rare as getting a corrupt bit while downloading a web page, or checking mail.) So I wouldn't expect the noise to be coming from the 2.4Ghz side.

But on the analog side, it's easy to pick up junk: think of how many PA systems had CB radio interference back in the Olden Days when everyone had a CB in their car. ("We got us a convoy!")

(Or it could be like my PC and cell phone at work... I know when I'm getting a cell call before my phone rings because my PC speakers start emitting some horrible sounds.)

I would look at the analog side of things: is the SB connected to an external DAC or using the internal one? Have you tried replacing any analog cables? Is there a ground problem (which is what I think is causing my cellphone-pc interference at work..)?

Signal noise in the 2.4Ghz range would lead to dropouts (when the buffer emptied), but not to noise in the audio.

radish
2006-01-23, 11:51
this does not eliminate the "static" from low signal strength

Just to be clear, to avoid confusion, whilst the low signal strength and the noise may be related (i.e. caused by the same interference) the low signal is almost certainly not causing the noise. With network transmissions (like the audio to the SB) the data either arrives or it doesn't - there's no variation in quality.

kwlinca
2006-01-23, 12:43
The analog interconnects in the system are of high quality (Harmonic Tech Truthlinks) and are well shielded. If the interference was local, "static" (due to poor shielding) should occur regardless of signal strength.

Something happens to alter signal strength between uses. Perhaps the problem is server or router related, though I will definitely try changing router channels.

snarlydwarf
2006-01-23, 13:00
If the interference was local, "static" (due to poor shielding) should occur regardless of signal strength.


I'm not saying the cause of the interference is local. It could be all sorts of external things (again, the cellphone that I for some reason stick next to my head that drives my PC speakers nuts...). That's not coming from the PC or the speakers -- it's RF from the headphone that is being picked up by something somewhere after the analog chain starts in the PC.



Something happens to alter signal strength between uses. Perhaps the problem is server or router related, though I will definitely try changing router channels.

Maybe I'm not being clear...

The drop in signal strength is very likely related to the source of your audio problems, but not on the 2,4Ghz side.

Something is most likely spewing tons of RF at you. The 2.4Ghz network sees this as a loss of signal strength (the noise is so overwhelming that it wipes out the carrier).

The side effect (again, like my cell phone at work.. actually, it's not just my old Nokia -- any cell phone will do it) is that something in your setup is seeing some sort of subfrequency of that noise and routing it to your speakers. When my cell phone transmits, my sound card or the cable powering the speakers or the cable driving the speakers picks up the transmission from the phone and my speakers make the most god-awful sounds imagineable. It's not the fault of the Linux Kernel, SoftSqueeze or XMMS, and probably not even the fault of the soundcard, though maybe it is an insufficient ground on the card.

Likewise, your sound is coming from somehere past your DAC (corruption in the digital stream won't be static -- it will be total noise... even a single bit error in a frame is painful to hear), whether that's the SB's internal DAC (ie if you're using analog outputs) or an external DAC (if you're using the digital).