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Old 15-09-2008, 10:47
Oldjim
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I will soon be buying an LCD HD TV (Approx 42") and I have been advised that a mains filter will improve the picture.
Is this the case or is it mostly hype.
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Old 15-09-2008, 11:37
Nigel Goodwin
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I will soon be buying an LCD HD TV (Approx 42") and I have been advised that a mains filter will improve the picture.
Is this the case or is it mostly hype.
It's certainly mostly hype, and probably completely hype - I seriously doubt it will make the slighest bit of difference.
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Old 15-09-2008, 11:56
Glawster2002
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I think for high-end Hi-fi mains filters can make a difference, especially as you're listening to analogue devices where a voltage spike would be amplified along with the analogue signal.

Whether the same could be said for a digital display, however, is less convincing unless the interference was such that a '0' was misinterpreted as a '1', but I think that would be unlikely..
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Old 15-09-2008, 12:01
stugster
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Do televisions not have transformers then? Or at best, capacitors?
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Old 15-09-2008, 13:19
Nigel Goodwin
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Do televisions not have transformers then? Or at best, capacitors?
They have switch-mode PSU's, these take the mains and filter it, then rectify it to DC, smooth it, and finally chop it at a high frequency and feed a small HF transformer.

Even for analogue HiFi, it will make no difference - if you're getting mains spikes coming out of your speakers you need to get your faulty supply sorted out - it's also unlikely a simple filter would remove the spikes anyway.
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Old 15-09-2008, 13:45
Deacon1972
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I think for high-end Hi-fi mains filters can make a difference, especially as you're listening to analogue devices where a voltage spike would be amplified along with the analogue signal.

Whether the same could be said for a digital display, however, is less convincing unless the interference was such that a '0' was misinterpreted as a '1', but I think that would be unlikely..
Dirty mains and CRT technology didn't go together well either, the filters were good enough to filter out RF interference but not spikes and surges.

An inconsistent mains supply doesn't affect everyone, and you don't have to live near an industrial estate to be affected.

I respect some of what Russ Andrews does but not the prices he charges.

Purists used to fit UPS, the ones where it converted the AC to DC then back to AC, this way a constant power supply can be maintained.

As in most things AV there are believers and non believers, so long as you don't go paying huge amounts of money there's no harm in trying it, you never know.
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Old 15-09-2008, 14:26
Glawster2002
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As in most things AV there are believers and non believers, so long as you don't go paying huge amounts of money there's no harm in trying it, you never know.
Which is precisely why I used the phrase 'can make a difference.'

As you say, there's no harm in trying these things to see if it makes a difference to your system, or not as the case may be, but I would certainly never say it's anything like a "must have" accessory and if someone buys a mains filtering system and they're happy with what they've brought then good luck to them I say.

As I've said before on other threads like this, if someone's happy to spend their own money and get a system they're happy with, then who am I, or anyone else for that matter, to criticize what they've spent their money one.
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Old 15-09-2008, 16:05
+3dB
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A filter can protect against spikes damaging your equipment or manifesting themselves as glitches, but they won't make the slightest bit of difference to the picture quality.

By all means spend 30 on a decent filter, but don't fall for the marketing BS or so-called experts who have to convince themselves they can see a difference in order to justify the crazy money they've wasted.
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Old 15-09-2008, 16:30
bobcar
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I think a surge protection socket is well worth it (they don't cost much) and it should include EMI suppression as well. I've seen several cases where Freeview boxes have been jittering every time a fridge or central heating switches on and the EMI suppression has cleared this. (Yes the interference could have been cured at the source as well).

Don't expect this to improve the PQ though.
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Old 15-09-2008, 19:04
Orbitalzone
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I think a surge protection socket is well worth it (they don't cost much) and it should include EMI suppression as well. I've seen several cases where Freeview boxes have been jittering every time a fridge or central heating switches on and the EMI suppression has cleared this. (Yes the interference could have been cured at the source as well).

Don't expect this to improve the PQ though.

I'd go along with that.... I've seen (some years ago) a video recorder that had a mind of its own in a customers house, we replaced it and the same thing happened on the replacement, after fitting a surge protector the problem went away instantly. We never found the cause but assume a fridge/boiler/flourescent light was causing the interference.

Plus of course a surge protector reduces the chance of damage due to power spikes and surges.
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Old 15-09-2008, 22:44
Oldjim
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Thank you for the very clear and helpful responses.
This more or less confirms what I thought but adding a surge protector would be sensible given that I have one on all the computers even though it hasn't had to do anything yet.
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Old 16-09-2008, 00:28
bobcar
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Thank you for the very clear and helpful responses.
This more or less confirms what I thought but adding a surge protector would be sensible given that I have one on all the computers even though it hasn't had to do anything yet.
How do you know they haven't had to do anything?
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Old 16-09-2008, 10:29
Orbitalzone
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How do you know they haven't had to do anything?
Indeed, a surge protector appears to do nothing but you can't really tell when it has protected you against a surge, they rarely blow when activated.
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Old 16-09-2008, 11:46
njp
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Indeed, a surge protector appears to do nothing but you can't really tell when it has protected you against a surge, they rarely blow when activated.
My various attempts to investigate whether domestic surge protectors do anything that's worth doing have not been entirely conclusive, but I'm inclined to think that they are mostly snake oil. I don't use them on anything.
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Old 16-09-2008, 12:25
Orbitalzone
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We used to supply them to customers that had variable mains supplies (out in the countryside) and a surge protector did stop many problems from blown fuses to damaged powersupplies.

They certainly do protect from surges and spikes....

A mains conditioner is another matter and I can't really comment as I've never bothered with them... I imagine for servers they might be very useful but for the average bit of kit?

Kind of like those 90 braided mains cables hehehe
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Old 16-09-2008, 13:38
njp
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We used to supply them to customers that had variable mains supplies (out in the countryside) and a surge protector did stop many problems from blown fuses to damaged powersupplies.
This is where my scepticism kicks in. I simply don't believe (having looked at some specs) that a tiny surge protector would be able to shunt sufficient energy to prevent a mains fuse blowing, even if it sacrificed itself in the process - assuming you are talking about a normal fuse, rather than an exotic quick-blow device inside an appliance (and perhaps not even then). The joule rating of the MOV is far too low to cope with a surge of that magnitude.

As I said, I know they do something (unlike exotic mains cables). I'm just not convinced it's worth doing!
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Old 16-09-2008, 13:54
Nigel Goodwin
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This is where my scepticism kicks in. I simply don't believe (having looked at some specs) that a tiny surge protector would be able to shunt sufficient energy to prevent a mains fuse blowing, even if it sacrificed itself in the process - assuming you are talking about a normal fuse, rather than an exotic quick-blow device inside an appliance (and perhaps not even then). The joule rating of the MOV is far too low to cope with a surge of that magnitude.
An internal fuse can be blown by a fairly small spike, it's quite likely that a MOV could absorb enough energy to prevent this.
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Old 16-09-2008, 13:56
Oldjim
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How do you know they haven't had to do anything?
Only because the various electronic components such as routers which aren't protected haven't shown any problems.
Actually my biggest problem wouldn't be expected to be noise but voltage spikes given that we get fairly frequent power cuts due to overhead wires passing through trees. However given that my existing Belkin Surgemaster apparently has a clamping level of 6000 volts it probably won't be too effective against that although the latest model has a clamping level of 250 volts. That may be a reason to get some new ones
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Old 16-09-2008, 21:09
Orbitalzone
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in reply to NJP;

Well I can only say that from the many times we used them for customers (and myself) surge protectors do work, a surge could be very quick and as Nigel has said, it can sometimes just blow a fuse.....so something like a surge protector will further protect against it.

I won't try and convince you but will say that we used many when supplying expensive audio and video equipment. Note that we didn't sell them but gave them away with the equipment as it often saved our engineers having to repair destroyed swith mode power supplies... equipment damaged by a surge isn't really covered by the manufacturs warranty and the customer rarely believed it was a surge (or didn't want to beleive) so for our own sakes we used them and they certainly helped... other surge protectors worth considering are for phonelines as static down lines can ruin digiboxes, phones, modems etc.

I've come across a number of damaged equipment connected by phone that's due to surges... often after a thunderstorm maybe zapped some phone lines a few miles away.
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Old 18-11-2008, 16:39
billyc
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What Hi-Fi has recommended the Lindy mains conditioner this month, http://whathifi.com/Review/Lindy-6-way/ and according to the Lindy website they've reduced the price down to 34.99 - a bit more affordable than Russ Andrews.
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Old 18-11-2008, 22:59
martytoo
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Coming back to the original point, assuming the TV is Digital the answer is no. Mains born noise will be Analogue and as such will be ignored or filtered out by The TV's circuitry.
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Old 19-11-2008, 13:01
Nigel Goodwin
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Coming back to the original point, assuming the TV is Digital the answer is no. Mains born noise will be Analogue and as such will be ignored or filtered out by The TV's circuitry.
As it will on analogue as well - all sets have mains filtering anyway.

One point to note though, UK mains is so good that UK specific TV's usually have less mains filtering than those for other countries where the mains is far poorer.

But the current trend towards EU wide sets means we get extra un-needed filtering as well.
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Old 19-11-2008, 23:28
zaeon
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As it will on analogue as well - all sets have mains filtering anyway.

One point to note though, UK mains is so good that UK specific TV's usually have less mains filtering than those for other countries where the mains is far poorer.

But the current trend towards EU wide sets means we get extra un-needed filtering as well.
Point to note...
For many years we here in the UK had a mains voltage of 240v. This changed about 5 years ago now to a standard to bring us in line with most of Europe - 230v (+10%/-6%, not sure why the differential was set so). Since that happened I have noticed that, during times of peak demand, the voltage varying (rising in some cases to 265v) and the number of spikes and bursts of noise increase, So it may be a wise move to add surge protectors and filters to equipment. Switch mode PSU's are everywhere these days, even in your mobile phone charger!!. BUT most of them lack the sophisticated and solid protection circuitry that you find in Computer PSU's. Anyone who had a power failure on a Pace Satellite reciever will know what I'm getting at., and now we have PVR's with disk drives that could very easily come a cropper if they get too many interruptions on the supply. This is why it is good safe practice to "park" a HardDisk drive's heads, when not accessing data.( Usualy results in "hard" disk errors, too many of these and you can kiss the HD goodbye). Which makes it all the more surprising the Sky+ and Sky HD recorder boxes have the heads unparked and the disk constantly spinning.
Back to the original point about a mains filter improving the picture - not on a digital set, you have all that error correction during processing of the data. On an Analoge reciever....Possibly, but the improvement would probably be only noticable on a High-end High-Spec model.
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Old 20-11-2008, 00:22
bobcar
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Coming back to the original point, assuming the TV is Digital the answer is no. Mains born noise will be Analogue and as such will be ignored or filtered out by The TV's circuitry.
It doesn't matter whether the TV is digital or analogue interference can get through via the mains. Apart from the fact it makes technical sense I have seen this several times in fact digital is much more susceptible.

If the OP expects a "better" or "sharper" picture etc then they won't get this with either analogue or digital TV but if the question is will a mains surge protector/suppressor be worth it then the answer is probably yes.
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Old 20-11-2008, 01:03
njp
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Point to note...
For many years we here in the UK had a mains voltage of 240v. This changed about 5 years ago now to a standard to bring us in line with most of Europe - 230v (+10%/-6%, not sure why the differential was set so).
The voltage tolerances were carefully arranged so that no country needed to change its native voltage in order to achieve EU harmonisation. UK voltage is the same as it ever was.

Since that happened I have noticed that, during times of peak demand, the voltage varying (rising in some cases to 265v) and the number of spikes and bursts of noise increase, So it may be a wise move to add surge protectors and filters to equipment.
Peak demand usually results in voltage and frequency reductions, so I'm puzzled at those results. I suppose you might get spikes as extra generating capacity joins the grid if the balancing engineers aren't doing their job properly, but I wouldn't expect them to be of sufficient magnitude to be shunted by a MOV (as used in typical domestic surge suppressors, which I'm increasingly convinced are of no practical value).

and now we have PVR's with disk drives that could very easily come a cropper if they get too many interruptions on the supply. This is why it is good safe practice to "park" a HardDisk drive's heads, when not accessing data.( Usualy results in "hard" disk errors, too many of these and you can kiss the HD goodbye). Which makes it all the more surprising the Sky+ and Sky HD recorder boxes have the heads unparked and the disk constantly spinning.
All modern hard drives auto-park the heads when the power is switched off. In any case, a momentary interruption in the power supply won't cause this to happen, because the platters will still be spinning at operational speed. The point of having the disc constantly spinning in a PVR is so that it can buffer the incoming data, so that the user can pause and rewind live TV. Not doing that would severely reduce the usefulness of the device, with very little gain (apart from a modest reduction in power consumption).
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