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even faster broadband

 
 
Murray Symon
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      08-18-2010
Stephen Worthington wrote:

> On Tue, 17 Aug 2010 12:38:30 +0000 (UTC), Sweetpea
> <(E-Mail Removed)> wrote:
>
>>On Wed, 18 Aug 2010 00:28:59 +1200, Stephen Worthington wrote:
>>
>>> The VDSL2 splitters are better as the filtering has a very sharp cutoff
>>> to allow more bandwidth for the DSL signals.

>>
>>How does that sharp filter affect the quality of sound on the telephone
>>line?

>
> Not at all. The cutoff is still in the same place.



"Sound quality" and "telephone line" in the same sentence??
I thought that was just a sly joke at the expense of audiophiles.
I remember the old days of debating CD player brickwall filters.
I think some people must still react to the phrase "sharp cutoff"
by getting upset about degraded sound reproduction.

 
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Sweetpea
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      08-18-2010
On Wed, 18 Aug 2010 20:01:14 +1200, Stephen Worthington wrote:

> On Tue, 17 Aug 2010 12:38:30 +0000 (UTC), Sweetpea
> <(E-Mail Removed)> wrote:
>
>>On Wed, 18 Aug 2010 00:28:59 +1200, Stephen Worthington wrote:
>>
>>> The VDSL2 splitters are better as the filtering has a very sharp
>>> cutoff to allow more bandwidth for the DSL signals.

>>
>>How does that sharp filter affect the quality of sound on the telephone
>>line?

>
> Not at all. The cutoff is still in the same place.


No phase distortion at higher audio frequencies?


--
"Filtering the Internet is like trying to boil the ocean"
 
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Sweetpea
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      08-18-2010
On Wed, 18 Aug 2010 20:17:34 +1200, Murray Symon wrote:

> Stephen Worthington wrote:
>
>> On Tue, 17 Aug 2010 12:38:30 +0000 (UTC), Sweetpea
>> <(E-Mail Removed)> wrote:
>>
>>>On Wed, 18 Aug 2010 00:28:59 +1200, Stephen Worthington wrote:
>>>
>>>> The VDSL2 splitters are better as the filtering has a very sharp
>>>> cutoff to allow more bandwidth for the DSL signals.
>>>
>>>How does that sharp filter affect the quality of sound on the telephone
>>>line?

>>
>> Not at all. The cutoff is still in the same place.

>
>
> "Sound quality" and "telephone line" in the same sentence?? I thought
> that was just a sly joke at the expense of audiophiles. I remember the
> old days of debating CD player brickwall filters. I think some people
> must still react to the phrase "sharp cutoff" by getting upset about
> degraded sound reproduction.


Steep filters, unless they're very well designed, generally have issues
with phase shift at higher frequencies.

While telephone lines do have a limited audio bandwidth (and this is
perfectly fine when you consider their primary purpose - communication of
speech) one would expect that the analogue/digital/analogue signal being
pushed through a telephone line wouldn't have any distortion deliberately
introduced by the telephony equipment other than to limit the bandwidth.


--
"Filtering the Internet is like trying to boil the ocean"
 
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Lawrence D'Oliveiro
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      08-18-2010
In message <i4g4ut$2u81$(E-Mail Removed)>, Murray Symon wrote:

> "Sound quality" and "telephone line" in the same sentence??


Aye, telephone engineers do take their 3.5kHz frequency response seriously.
Got to make sure your customers can understand each other, you know.

I myself suffered from a sound-quality problem on the line, which the
Telecom folks were kind enough to fix over the weekend.

> I remember the old days of debating CD player brickwall filters.


You can do a brickwall filter in the digital domain, not in the analog one.
 
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victor
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      08-18-2010
On 18/08/2010 8:10 p.m., Lawrence D'Oliveiro wrote:
> In message<(E-Mail Removed) >, Stephen Worthington
> wrote:
>
>> On Tue, 17 Aug 2010 12:38:30 +0000 (UTC), Sweetpea
>> <(E-Mail Removed)> wrote:
>>
>>> On Wed, 18 Aug 2010 00:28:59 +1200, Stephen Worthington wrote:
>>>
>>>> The VDSL2 splitters are better as the filtering has a very sharp cutoff
>>>> to allow more bandwidth for the DSL signals.
>>>
>>> How does that sharp filter affect the quality of sound on the telephone
>>> line?

>>
>> Not at all. The cutoff is still in the same place.

>
> Hard to believe. Analog filters with sharp cutoffs tend to have phase-shift
> issues.


How would you hear that ?
 
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victor
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      08-18-2010
On 18/08/2010 8:01 p.m., Stephen Worthington wrote:
> On Tue, 17 Aug 2010 12:38:30 +0000 (UTC), Sweetpea
> <(E-Mail Removed)> wrote:
>
>> On Wed, 18 Aug 2010 00:28:59 +1200, Stephen Worthington wrote:
>>
>>> The VDSL2 splitters are better as the filtering has a very sharp cutoff
>>> to allow more bandwidth for the DSL signals.

>>
>> How does that sharp filter affect the quality of sound on the telephone
>> line?

>
> Not at all. The cutoff is still in the same place.


There is quite a gap between the upper frequency of the phone channel at
3.5kHz and the lower band of ADSL at 25kHz.

Here is some Telecom info

http://www.telepermit.co.nz/PTC285iss4_06-2010.pdf
http://www.telepermit.co.nz/PTC280.pdf

As they point out, in addition to isolating your phone audio from DSL
noises and isolating your router from the phone system interference, a
central splitter might stop your home phone wiring radiating RF
interference to your radio etc.

Here's a splitter on Tardme
http://www.trademe.co.nz/Browse/List...x?id=310661585
 
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victor
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      08-18-2010
On 16/08/2010 8:50 p.m., peterwn wrote:
> On Aug 15, 11:18 am, victor<(E-Mail Removed)> wrote:
>> the report is
>> complete bullshit and the company should be embarrassed.
>> It contains a master splitter for adsl/vdsl and has no more benefit to
>> your broadband speed than installing a master splitter at the
>> demarcation point.

>
> Anyone knows where you can buy these master splitters. Neither Dickies
> or Jaycar have them. I have used one of the ordinary plugin splitters
> as a master splitter but am feeling uncomfortable with it (I install a
> 'slave' jack near demarc, plug a splitter into it, terminate the rest
> of the wiring into a BT plug and plug it into the splitter).


Dynamix or one of their resellers

http://www.dynamix.co.nz/index.html?...TER&ID=3291922
 
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Dave Doe
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      08-19-2010
In article <c2505102-0ce8-4a32-9a8f-
http://www.velocityreviews.com/forums/(E-Mail Removed)>, (E-Mail Removed) says...
>
> On Aug 15, 11:18*am, victor <(E-Mail Removed)> wrote:
> > the report is
> > complete bullshit and the company should be embarrassed.
> > It contains a master splitter for adsl/vdsl and has no more benefit to
> > your broadband speed than installing a master splitter at the
> > demarcation point.

>
> Anyone knows where you can buy these master splitters. Neither Dickies
> or Jaycar have them. I have used one of the ordinary plugin splitters
> as a master splitter but am feeling uncomfortable with it (I install a
> 'slave' jack near demarc, plug a splitter into it, terminate the rest
> of the wiring into a BT plug and plug it into the splitter).


Tastech have just got them...

http://www.tastech.co.nz/product_inf...ucts_id=330212

--
Duncan.
 
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Lawrence D'Oliveiro
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      08-19-2010
In message <i4hhpm$ns8$(E-Mail Removed)-september.org>, victor wrote:

> On 18/08/2010 8:10 p.m., Lawrence D'Oliveiro wrote:
>
>> Analog filters with sharp cutoffs tend to have phase-shift issues.

>
> How would you hear that ?


Transients.
 
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Murray Symon
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      08-19-2010
Lawrence D'Oliveiro wrote:

> In message <i4g4ut$2u81$(E-Mail Removed)>, Murray Symon wrote:
>
>> "Sound quality" and "telephone line" in the same sentence??

>
> Aye, telephone engineers do take their 3.5kHz frequency response
> seriously. Got to make sure your customers can understand each other, you
> know.
>
> I myself suffered from a sound-quality problem on the line, which the
> Telecom folks were kind enough to fix over the weekend.
>
>> I remember the old days of debating CD player brickwall filters.

>
> You can do a brickwall filter in the digital domain, not in the analog
> one.


You can implement them either way, both of which can be tricky and
result in unwanted artifacts. Digital keeps component costs down.
 
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