digital radios

[The Natural Philosopher]

Not necessarily. Certainly no worse than vinyl records

Lets face it,. 100:1 difference (20dB) in channels is available with the meaneet of equipment. That puts the mage firmly at the edge of one loudspeaker. Most meaningful stereo is in the 2-3 times difference only.

ISTR that I could get around 40dB with a good chipset and reasonable signal; level - 10uv or so, certainly better than 30dB in the mid range, tailing off a bit above 4Khz..but there isn't a lot of info in the last two octaves anyway.

Its unusual to get more than 40db crosstalk rejection in a stereo amp anyway...especially at higher freqs where capacitative coupling across e.g. tone control wiring tends to screw things up.

[Andy Champ]

Hic? Been at the whisky? :)

IIRC stereo on Vinyl is done by the two axes that the needle gets pushed in - both 45 degrees from vertical. And it's very hard to move in one axis and not the other, which limits separation.

Or many other digital technologies. I think it's actually a waste of bandwidth; that hiss on FM is way lower on digital systems, so sum and difference, or something more sophisticated is the way to go.

Mind, if you have the bandwidth and not the CPU power (which was the case when CD was designed) send them both in full.

Andy

[Dave Plowman (News)]

Heh heh - you should have seen the crosstalk between channels on the Studer A800 2" 24 track which were the R-R of analogue machines. So bad that if you had time code on track 24, you couldn't really use tk 23...

[The Natural Philosopher]

Mmm. yerss, I DO remember that because I DID have a time code actually ON a tape track as well.

[tony sayer]

Never used in the UK 'tho they do have Two subcarrier allocations for use in the USofA..

[tony sayer]

In article , Dave Plowman (News) scribeth thus

What we're they measuring at?..

[tony sayer]

Some are a Tad better than that NP;!..

And tuners too!...

[Dave Plowman (News)]

Your ears will do. Timecode is a series of pulses so gets on everything it shouldn't. ;-) So not only did you not want to hear it on a audio track but needed to be protected from too much corruption.

[The Natural Philosopher]

ISTR most of the so called 'good stuff' could do about 60dB SNR on a turntable picklup, and similar on a very strong VHF, and scrape in -50dB or so crosstalk, getting worse over 1Khz..

But its been a long time..

[tony sayer]

In article , Dave Plowman (News) scribeth thus

Well yes you can hear it but you should measure it to see if it comes within spec .. it might have been the machine had a fault on it.

Or were they all like it?..

[Dave Plowman (News)]

Crikey - hope none of the old Thames maintenance engineers read this. ;-) They were maintained scrupulously. Far better than at the BBC - and that applied to all tape machines.

Indeed - we had three. It was part of the Studer spec that you either left a guard track or used it carefully for something that didn't much matter.

[The Natural Philosopher]

there is always a certain amount of magnetic and capacitative leakage across tracks on any machine. Very good machines had screens and stuff put in..but even the best TAPE will ghost through to the layer below if left too long on a reel.

One good reason to go digital really.

Crosstalk doesn't happen. Or if it does, its so corrupted as to be unusable

[geoff]

In message , tony sayer writes

Thread hijack ...

I bought some speaker cable from CPC the other day

"4mm separation between conductors to minimise crosstalk"

WTF ???

[Dave Plowman (News)]

CPC seem to just print maker's blurb without thinking. See the post about CFL floodlights - 35 watt said to be a 300 watt equivalent. TLC selling the same thing changed it to 150 watt. But charge more. ;-)

[tony sayer]

Yes it has .. I'll measure a couple of relatively modern ones when I get a moment...

[D.M. Procida]

My children's little Sony stereo starts up a cooling fan when you turn it to DAB! How amazingly rubbish is that?

Daniele

[Mike Barnes]

In this house we often have several FM receivers going at once, and they're perfectly synchronised, and the pips are precisely on the hour. Does anyone know, would DAB+ do that? If not, I've no interest in it.

[Dave Plowman (News)]

It certainly won't be synchronised with FM - no digital medium can be. I also doubt they'll all be exactly the same as one another either - this doesn't happen with any of the current digital systems.

Not a problem here, though. Over 30 years ago I installed cabling that allows me to listen (and watch) to the same source in any or all of the rooms. The reason for this was the appalling FM reception of certain stations in this part of London which made portable radios pretty useless.

[David Hansen]

On Mon, 19 Jan 2009 10:46:04 +0000 someone who may be Mike Barnes wrote this:-

No.

If you used the same receivers in each room then they might be in step if you are lucky. However, the pips will not be at the right time due to the delays introduced by encoding and decoding them.

[The Natural Philosopher]

gosh, a correct statement from dynamo dave.

Actually even the FM pips aren't always on time either.

Not according to this NTP synchronised computer anyway. Up to a second or so late..you can add another second or two for the digital radio stuff on freeview.