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Humax FreeSat PVR video problems

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Keef
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Postby Keef » Sat Jul 21, 2012 1:04 pm

Steve, it's cruel to mock those folks who think diamond-encrusted gold cables make their digital audio sound better.
You and I know, of course, that the audio should never have been converted from analogue to digital in the first place.

I once stuck up a length of salty wet string and loaded it up on 1.8MHz. It actually loaded and worked (over a 50 mile path), but it heated up and steamed the water off, whereupon it stopped working.
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Colonel Panic
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Re: Humax FreeSat PVR video problems

Postby Colonel Panic » Sat Jul 21, 2012 1:41 pm

Whilst I accept that there should be no difference between cable A and cable B in terms of dots and dashes, I do find it difficult to believe that all cables are the same. What about shielding etc - and what about cable length? Is an el-cheapo cable going to be as good as an expensive one over, say, 10 metres?

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Keef
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Postby Keef » Sat Jul 21, 2012 2:32 pm

There is a basic standard that cables need to achieve to be suitable for purpose. That standard will vary based on the signal in the cable and the cable length. Once that standard is met, anything more is unnecessary.

For low-level signals in an area where there are high-power transmitters, shielding and quality of termination matter a lot. In a house with nothing else around, they are less critical.
I would want audio leads to be twisted-pair and shielded, and I would want to know the inductance and capacitance of the lead. For digital signals, I would want shielded (to stop the signal interfering with radios etc in the vicinity) but wouldn't be fussed about the rest.

For loudspeaker leads, I care about resistance (a lot), inductance and capacitance (a bit). I would not spend vast amounts on oxygen-free cable, although there are those who do.
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Boing_737
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Postby Boing_737 » Sat Jul 21, 2012 3:30 pm

Colonel Panic wrote:Whilst I accept that there should be no difference between cable A and cable B in terms of dots and dashes, I do find it difficult to believe that all cables are the same. What about shielding etc - and what about cable length? Is an el-cheapo cable going to be as good as an expensive one over, say, 10 metres?


Put it this way. gigabit Ethernet would be extremely sensitive do data corruption, but can run perfectly happily on unshielded cable for 100 metres using cat 5e or cat 6 cable. It is ALOT cheaper per metre than the wonder cables sold by the so called hi-fi experts....

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stevelup
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Postby stevelup » Sat Jul 21, 2012 5:33 pm


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Melanie
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Postby Melanie » Sat Jul 21, 2012 7:52 pm

6 year-old 32" Humax with PVR (cost £1500 when new from QVC). Hard disk started playing up with bad video picture, then the PVR Recorded Menu's went the same way, and finally you couldn't bring up the PVR section at all. Ripped the thing apart (bad move - one and a half hours and over 80 screws just to get to the PVR board). Replaced 1000uF 16v Capacitor on the board (clue was badly deformed top when all the others were perfectcly flat). All fine thereafter. Shouldn't have wasted half a day out of my life, as the whole thing died around a month later - about the only thing I rescued working was a 40Gb Hard Disk - whoopie!

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Postby Rob P » Mon Jul 23, 2012 8:10 am

stevelup wrote:This is my favourite thing in the whole world...


Some of the comments are priceless :)

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Paul_Sengupta
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Postby Paul_Sengupta » Mon Aug 06, 2012 1:30 am

Colonel Panic wrote:PS What is "wet string"? :?


String which is wet. Normally, string is dry, and therefore will not conduct electricity. Wet string will, at least partially.

It's normally used in the context of an antenna..."Wow, the signal is so strong here that you could get a picture on a 6 inch piece of wet string."

Glad to see Keef has tried even transmitting on said string.

stevelup wrote:I soaked 15 cm of string in salt water and stuck a phono plug on each end. It of course worked perfectly and he couldn't tell which was his £400 cable in a blind AB test.


That's excellent! You could perhaps market it, though you may have problems with the string drying out and also with corrosion of the connectors...

But actually, using the same principle, I made a digital cable with some satellite TV coax and a couple of phono plugs to go between my CD player and DAC. Now I've got cheap ones of both, but I didn't think it sounded brilliant. I took them round to a friend's once, who had just bought a very expensive player and even more expensive DAC. He had brought a few cables back from the shop to try, one costing a few quid, another costing 50 quid and yet another costing 300 quid. We did blind tests on each other. We both agreed that his £2k+ set up sounded best with the £50 cable. Guess which one my £400 setup sounded best with? Yup, the £300 cable. Pfft. Anyway, we compared my home made cable and it sounded absolutely awful. On both. Don't think 75 ohm coax works all that well. I bought some silver wire audio coax stuff from Maplin and put phono plugs on that, and it sounded much much better.

So, for whatever reason, it does seem to make a difference.

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Postby Boing_737 » Mon Aug 06, 2012 7:35 am

Paul_Sengupta wrote:
That's excellent! You could perhaps market it, though you may have problems with the string drying out and also with corrosion of the connectors...



You just need to get a dog and tie it up behind the telly:

An elderly lady with a dog, called Bell Telephone to say that her telephone failed to ring when her friends called - and that on the few occasions when it did ring, her dog always barked before the phone rang.

The telephone repairman proceeded to the scene, curious to see this psychic dog or senile elderly lady. He climbed a nearby telephone pole, hooked in his test set, and dialed the subscriber’s house. The phone didn’t ring but the dog barked loudly and then the telephone didring.

Climbing down from the pole, the telephone repairman found:
1. The dog was tied to the telephone system’s ground post via an iron chain and collar;
2. The dog was receiving 90 volts of signaling current when the phone number was called;
3. After several such jolts, the dog would start barking and urinate on the ground; and
4. The wet ground would complete the circuit and the phone would ring.

Which shows you that some problems can be fixed by grounding your dog...

Read more: http://www.joe-ks.com/archives_jan2004/ ... z22kH3NUql

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stevelup
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Postby stevelup » Mon Aug 06, 2012 7:54 am

Paul_Sengupta wrote:So, for whatever reason, it does seem to make a difference.


Indeed, between a CD player and DAC, it can make a difference because you can get quite bad jitter. It's really old technology and the clock signal is difficult to recover. Interestingly, there is little relationship between how much you spend on the gear and how sensitive it is to jitter. Some really cheap consumer stuff was completely impervious to it, and many 2k+ transport/DAC combos were horrendous...

My experiment was a Dolby Digital signal between a DVD player and Receiver - which doesn't suffer in this way.

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