ultrawomble
Sith Lord
I was simply wondering what the most common RFI ingress mechanism is perceived to be. I've never encountered mobile interference on my hifi (metal casework), but I have on the digi-box (plastic case) for the old CRT.
Russ Andrews - Sawyers Disc Technology
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I was simply wondering what the most common RFI ingress mechanism is perceived to be. I've never encountered mobile interference on my hifi (metal casework), but I have on the digi-box (plastic case) for the old CRT.
Alan Sircom
I dü werds, me
Good point, and I agree. The more the casework acts like a faraday cage, the less likely you are to hear this, although poorly shielded cables can also cause RFI breakthrough.
I'm just wondering if that's all, or there's something else at play. My wi-fi router crapped out a couple of weeks back and everything sounded a lot better, even with nicely shielded products (but no fancy cables, tables or conditioners at this time). Then I got a replacement and the sound got worse again.
No, it doesn't. If it did it would get enormously hot in use. Remember a kettle is about 2.2kW and the proof is that it gets enormously hot in use. It boils water after all! A cable that took a significant portion of this energy would get very hot very quickly and probably melt. A 5 minute test of your own kettle lead will demonstrate that it stays fairly cool in use.
A dimmer switch works by switching the power on and off (that's why they generate so much interference, incidentally). Instead of the light getting the full up-and-down waveform, the dimmer ensures that it only sees the wave crests then switches off until the next crest or trough comes along.
I can demonstrate that my ordinary kettle lead has virtually zero resistance, in order that it can transmit the 9 amps approx that my kettle uses without loss.
sq225917
Bit of this, bit of that
Well my phonostage picks up the phone buzz, thing is, putting the mobile on the end of the 2m long kettle lead, as opposed to generally 2m away from the box, does bugger all to increase the volume, putting it on the case does- ergo, point of ingress is casework not cable.
Craig, my name is Simon Clark. Please stick around to answer some more questions, input from people at the sharp end of hifi product development/ technology is always welcome- though you may find some of us somewhat abrasive. We don't mean to offend we just like our earth, well, flat.
Craig, my name is Simon Clark. Please stick around to answer some more questions, input from people at the sharp end of hifi product development/ technology is always welcome- though you may find some of us somewhat abrasive. We don't mean to offend we just like our earth, well, flat.
This is alas typical. Wireless routers work in the GHz range, and put out a watt or more of digital RF - same sort of frequency and power as a mobile phone.
The so-called "network over mains", where the ring mains is used as the network signalling medium is going to be a real problem for mains purity once it gets a high level of take up. There is a growing lobby in radio DX enthusiasts whose hobby will effectively be wrecked by interference from this source.
The other ubiquitous interference source is CFL's. I haven't got around to measuring conducted noise, but radiative is massive. For those with a 'scope, plug in a 10x probe and wave it anywhere within a metre or so of a CFL - you easily pick up 4V p-p of garbage. By loading the probe with resistors you can work out that the effective impedance of the interference is 100k or so. It is unlikely to be an issue with low impedance signals, but anything with an effective impedance of 1-10k (a preamp with a 1k resistor in series feeding a power amp with 100k input) will pick this up a treat.
I certainly get a noticeable improvement in sound quality by turning the darned things off in the house.
Craig
Spot on.
If there were real gains to be had from this sort of thing, would not every manufacturer offer these things as standard?
Wise-up suckers!
Perhaps you need better equipment? My stuff sounds the same regardless of whether the router is on or off.
seyles
Retired Child
If the input is connected to a typical output stage, it will no longer be floating, but tied the the output impedance of the feeding equipment.
That's where those input shorting plugs come in handy, tying any unused inputs to ground, getting rid of the possible RF injection problems.
Steve.
Well done - you are clearly 100% satisified with your system. Must be nice to be so certain.
Craig
Alan Sircom
I dü werds, me
Given that I heard this on everything from my Tivoli radio right up to around £30,000 worth of equipment, what the hell are you using?
Are you playing your system from the inside of a microwave oven?
I am, thanks.
Until recently an Arcam CD36 into a C31 pre-amp and an Avondale power-amp, speakers are Harbeth SHL5s.
I've just discovered a Squeezbox Duet, which has replaced the CD player, it has a slight edge in sound quality and a huge advantage in convenience. (If you ignore havng to rip hundreds of CDs onto a computer!)
The router is upstairs.
Can you describe the kind of interference you're talking about?
I think, therefore I am!
Darth Vader
From the Dark Side
I think stray pickup is device orientated. I am fortunate to live in an area with 'clean' mains and the hash that I used to get in the city has gone leaving a nice inky-black silence.
However I use home plugs for my SOHO and when I switch the WiFi homeplug on I get the zit zit in the background but only through my phono stage. BTW I guess the zit zit is network handshaking as when a lot of data is being xmitted its more like a crunching sound. Its quiet but there.
FWIW the phono stage is a very good one indeed and it has extremely low hum on MC compared to some top phono stages like the TE Groove. I'm not sure whether the RF is mains or air born.
Cheers,
DV
However I use home plugs for my SOHO and when I switch the WiFi homeplug on I get the zit zit in the background but only through my phono stage. BTW I guess the zit zit is network handshaking as when a lot of data is being xmitted its more like a crunching sound. Its quiet but there.
FWIW the phono stage is a very good one indeed and it has extremely low hum on MC compared to some top phono stages like the TE Groove. I'm not sure whether the RF is mains or air born.
Cheers,
DV
Alan Sircom
I dü werds, me
Yep, the noise floor dropped noticeably and the tweeters sounded more soft-domey than metal-domey. Big change.
Alan Sircom
I dü werds, me
That could be an issue, but I love this dirty city (cue sax solo)
Nothing remotely like that, it is ridiculously consistent. I can max the volume (on all but the phono input) and there is nothing but a slight hiss with my ear pressed to the tweeters.
foxwelljsly
Me too, I ate one sour too.
Tina Turner and Mel Gibson go post-apocalypto-loco in Kent?More Mad Max meets Riddley Walker.
With Subtitels - intentional sic.
fyi
CFL - Compact fluorescent lamp
even though I have lots of them I didn't associate the abbreviation
However Googling led me to find CFL’s that work with Dimmer switches! - Almost as happy as when I was told you can still get ‘with lead’ solder.
I only switch wireless on when I need to VPN to work (on a rare day I work from home), avoid home plugs (but interested to read a gigabit model is now out). I live in a fairly new house and the mains quality seems good – I just don’t get enough time for music or a room big enough
Jason
CFL - Compact fluorescent lamp
even though I have lots of them I didn't associate the abbreviation
However Googling led me to find CFL’s that work with Dimmer switches! - Almost as happy as when I was told you can still get ‘with lead’ solder.
I only switch wireless on when I need to VPN to work (on a rare day I work from home), avoid home plugs (but interested to read a gigabit model is now out). I live in a fairly new house and the mains quality seems good – I just don’t get enough time for music or a room big enough
Jason
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