Just doing the speaker wires before plasterboard is fitted and had a
thought about sub woofer cable.
If I'm going from a 7.1 face plate to an architrave sub/speaker
wall/faceplate I guess I don't need a cable with proper ends made up?
Wondering what type of co-ax I should use if indeed that is all it is?


Cheers
Pete

On 27/06/2016 23:04, Pet @ www.gymratz.co.uk ;¬) wrote:
Just doing the speaker wires before plasterboard is fitted and had a
thought about sub woofer cable.
If I'm going from a 7.1 face plate to an architrave sub/speaker
wall/faceplate I guess I don't need a cable with proper ends made up?
Wondering what type of co-ax I should use if indeed that is all it is?

Depends a bit on if its a line level feed to an active sub, or an
amplified feed to either passive sub or an active one that will accept
high level inputs). For the former, a decent screened lead intended for
audio applications would be fine. For the latter, you could use a set of
speaker cables.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Tuesday, 28 June 2016 01:41:09 UTC+1, John Rumm wrote:
On 27/06/2016 23:04, Pet @ www.gymratz.co.uk ;¬) wrote:

Just doing the speaker wires before plasterboard is fitted and had a
thought about sub woofer cable.
If I'm going from a 7.1 face plate to an architrave sub/speaker
wall/faceplate I guess I don't need a cable with proper ends made up?
Wondering what type of co-ax I should use if indeed that is all it is?

Depends a bit on if its a line level feed to an active sub, or an
amplified feed to either passive sub or an active one that will accept
high level inputs). For the former, a decent screened lead intended for
audio applications would be fine.

tv coax is also fine for signal level audio, if you have any leftovers lying round.

For the latter, you could use a set of
speaker cables.

or any cable/flex with sufficient cross section of copper. That's all that matters with speaker leads, and that is far from critical. But not coax, too little copper.


NT

On 28/06/2016 06:19, wrote:
On Tuesday, 28 June 2016 01:41:09 UTC+1, John Rumm wrote:
On 27/06/2016 23:04, Pet @ www.gymratz.co.uk ;¬) wrote:

Just doing the speaker wires before plasterboard is fitted and had a
thought about sub woofer cable.
If I'm going from a 7.1 face plate to an architrave sub/speaker
wall/faceplate I guess I don't need a cable with proper ends made up?
Wondering what type of co-ax I should use if indeed that is all it is?

Depends a bit on if its a line level feed to an active sub, or an
amplified feed to either passive sub or an active one that will accept
high level inputs). For the former, a decent screened lead intended for
audio applications would be fine.

tv coax is also fine for signal level audio, if you have any leftovers lying round.

Its not very nice to terminate onto phono plugs etc though...

For the latter, you could use a set of
speaker cables.

or any cable/flex with sufficient cross section of copper. That's all that matters with speaker leads, and that is far from critical. But not coax, too little copper.

The significance of cross section will come into play with a fully
passive sub, but not so much with an active sub that also takes a high
level input.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Tuesday, 28 June 2016 11:16:43 UTC+1, John Rumm wrote:
On 28/06/2016 06:19, tabbypurr wrote:
On Tuesday, 28 June 2016 01:41:09 UTC+1, John Rumm wrote:
On 27/06/2016 23:04, Pet @ www.gymratz.co.uk ;¬) wrote:

Just doing the speaker wires before plasterboard is fitted and had a
thought about sub woofer cable.
If I'm going from a 7.1 face plate to an architrave sub/speaker
wall/faceplate I guess I don't need a cable with proper ends made up?
Wondering what type of co-ax I should use if indeed that is all it is?

Depends a bit on if its a line level feed to an active sub, or an
amplified feed to either passive sub or an active one that will accept
high level inputs). For the former, a decent screened lead intended for
audio applications would be fine.

tv coax is also fine for signal level audio, if you have any leftovers lying round.

Its not very nice to terminate onto phono plugs etc though...

not on flying leads, no. For faceplates it's ok. Thin horrible tv coax is fine on flyleads fwiw.

For the latter, you could use a set of
speaker cables.

or any cable/flex with sufficient cross section of copper. That's all that matters with speaker leads, and that is far from critical. But not coax, too little copper.

The significance of cross section will come into play with a fully
passive sub, but not so much with an active sub that also takes a high
level input.

yup. If it takes current it wants a bit of copper cross section for best results.


NT

In article ,
wrote:
Depends a bit on if its a line level feed to an active sub, or an
amplified feed to either passive sub or an active one that will accept
high level inputs). For the former, a decent screened lead intended
for audio applications would be fine.

tv coax is also fine for signal level audio, if you have any leftovers
lying round.

It's pretty awkward stuff to work with though - especially where space it
tight like in a flush AV wall outlet.

--
*To be intoxicated is to feel sophisticated, but not be able to say it.

Dave Plowman London SW
To e-mail, change noise into sound.

On 28/06/2016 01:41, John Rumm wrote:
On 27/06/2016 23:04, Pet @ www.gymratz.co.uk ;¬) wrote:
Just doing the speaker wires before plasterboard is fitted and had a
thought about sub woofer cable.
If I'm going from a 7.1 face plate to an architrave sub/speaker
wall/faceplate I guess I don't need a cable with proper ends made up?
Wondering what type of co-ax I should use if indeed that is all it is?

Depends a bit on if its a line level feed to an active sub, or an
amplified feed to either passive sub or an active one that will accept
high level inputs). For the former, a decent screened lead intended for
audio applications would be fine. For the latter, you could use a set of
speaker cables.

Thanks John,
I'm guessing it's going to be an active sub. Got to go check out the amp
spec. So presuming a powered amp would something like the following be OK?
http://www.maplin.co.uk/p/audio-sing...er-metre-xr15r
http://tinyurl.com/zdde2nx

It's got to nestle into 25mm trunking with 3 pairs of speaker wires so
no room for TV Coax but something like this would allow me to run a
length to a front output and a 2nd length to the back corner of the room
just in case it needs a more acoustically balance position.

Cheers
Pete

On 28/06/2016 13:54, Dave Plowman (News) wrote:
In article ,
wrote:
Depends a bit on if its a line level feed to an active sub, or an
amplified feed to either passive sub or an active one that will accept
high level inputs). For the former, a decent screened lead intended
for audio applications would be fine.

tv coax is also fine for signal level audio, if you have any leftovers
lying round.

It's pretty awkward stuff to work with though - especially where space it
tight like in a flush AV wall outlet.

I have a roll of RG59 left over but as you say it's going to be a
squeeze into an architrave wall plate with 2 speaker posts in there too.

I've just found half a drum of 4 pair screened used in a days gone by
for making RS232 leads.

I suppose that would be just as good if I can get it into the trunking?

On Tuesday, 28 June 2016 14:58:22 UTC+1, www.GymRatZ.co.uk wrote:
On 28/06/2016 13:54, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:

Depends a bit on if its a line level feed to an active sub, or an
amplified feed to either passive sub or an active one that will accept
high level inputs). For the former, a decent screened lead intended
for audio applications would be fine.

tv coax is also fine for signal level audio, if you have any leftovers
lying round.

It's pretty awkward stuff to work with though - especially where space it
tight like in a flush AV wall outlet.

I have a roll of RG59 left over but as you say it's going to be a
squeeze into an architrave wall plate with 2 speaker posts in there too.

The maplin stuff you linked to is fine for short flyleads. Whether it's ok for longer runs depends on cable C & output impedance.

I've just found half a drum of 4 pair screened used in a days gone by
for making RS232 leads.

I suppose that would be just as good if I can get it into the trunking?

Yup. If you've got it you may as well use it.


NT

On 28/06/2016 15:27, wrote:

The maplin stuff you linked to is fine for short flyleads. Whether it's ok for longer runs depends on cable C & output impedance.

I've just found half a drum of 4 pair screened used in a days gone by
for making RS232 leads.

I suppose that would be just as good if I can get it into the trunking?

Yup. If you've got it you may as well use it.

Just want to be 100% sure as it's all going to be plaster boarded over
in the next few days so no access to it from then on.

Cheers - Pete

On 28/06/2016 14:29, www.GymRatZ.co.uk wrote:
On 28/06/2016 01:41, John Rumm wrote:
On 27/06/2016 23:04, Pet @ www.gymratz.co.uk ;¬) wrote:
Just doing the speaker wires before plasterboard is fitted and had a
thought about sub woofer cable.
If I'm going from a 7.1 face plate to an architrave sub/speaker
wall/faceplate I guess I don't need a cable with proper ends made up?
Wondering what type of co-ax I should use if indeed that is all it is?

Depends a bit on if its a line level feed to an active sub, or an
amplified feed to either passive sub or an active one that will accept
high level inputs). For the former, a decent screened lead intended for
audio applications would be fine. For the latter, you could use a set of
speaker cables.

Thanks John,
I'm guessing it's going to be an active sub. Got to go check out the amp
spec. So presuming a powered amp would something like the following be OK?
http://www.maplin.co.uk/p/audio-sing...er-metre-xr15r
http://tinyurl.com/zdde2nx

It's got to nestle into 25mm trunking with 3 pairs of speaker wires so
no room for TV Coax but something like this would allow me to run a
length to a front output and a 2nd length to the back corner of the room
just in case it needs a more acoustically balance position.

Yup that looks ok - its not going to be moved about, so single core is
not going to hurt. The resistance will creep up a bit on long runs, but
I can't see a few metres of it being a problem.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Tuesday, 28 June 2016 16:15:26 UTC+1, www.GymRatZ.co.uk wrote:
On 28/06/2016 15:27, tabbypurr wrote:

The maplin stuff you linked to is fine for short flyleads. Whether it's ok for longer runs depends on cable C & output impedance.

I've just found half a drum of 4 pair screened used in a days gone by
for making RS232 leads.

I suppose that would be just as good if I can get it into the trunking?

Yup. If you've got it you may as well use it.

Just want to be 100% sure as it's all going to be plaster boarded over
in the next few days so no access to it from then on.

Then look up the cable's capacitance and the source unit's output impedance.

Cable resistance is a nonissue here, as long as the sub is active, ie has its own power lead as well as signal in.


NT

In article ,
wrote:
The maplin stuff you linked to is fine for short flyleads. Whether it's
ok for longer runs depends on cable C & output impedance.

It's very unlikely any common cable has a capacitance etc that would make
any difference with modern equipment on domestic runs.

--
*I get enough exercise just pushing my luck.

Dave Plowman London SW
To e-mail, change noise into sound.

On 28/06/2016 17:06, wrote:

Just want to be 100% sure as it's all going to be plaster boarded over
in the next few days so no access to it from then on.

Then look up the cable's capacitance and the source unit's output impedance.

I spent a long while trying to remember all that stuff back from my
Radio amateur years.

Ended up with some mad figures
The pre-amp outputs are 560 ohms
The closet cable I could find matched most of the numbers on the cable
outer but it had a few more twisted pairs. Mine is 4 x twisted pair with
aluminium screen and a screen ground/dump wire.

Capacitance was 50pf per foot (I think) and maximum length is about 12 foot.

Cable resistance is a nonissue here, as long as the sub is active, ie has its own power lead as well as signal in.

Just running it in now and it just fits in the trunking.

Running it past the first wall plate I've just broken 2 pairs out from
the bundle which will give me 2 more pairs to the opposite corner of the
room.

The last query would be should I connect the screen ground up to mains
ground/earth in a neighbouring power socket which I'm guessing will
indirectly connect up to the amp chassis via power lead or should I not
worry?

Worst case I suppose I can connect it up should there be an induced hum
or interference.

Cheers
Pete

On 29/06/16 11:13, Pet @ www.gymratz.co.uk ;¬) wrote:
On 28/06/2016 17:06, wrote:

Just want to be 100% sure as it's all going to be plaster boarded over
in the next few days so no access to it from then on.

Then look up the cable's capacitance and the source unit's output impedance.

I spent a long while trying to remember all that stuff back from my
Radio amateur years.

Ended up with some mad figures
The pre-amp outputs are 560 ohms
The closet cable I could find matched most of the numbers on the cable
outer but it had a few more twisted pairs. Mine is 4 x twisted pair with
aluminium screen and a screen ground/dump wire.

Capacitance was 50pf per foot (I think) and maximum length is about 12 foot.

Cable resistance is a nonissue here, as long as the sub is active, ie has its own power lead as well as signal in.

Just running it in now and it just fits in the trunking.

Running it past the first wall plate I've just broken 2 pairs out from
the bundle which will give me 2 more pairs to the opposite corner of the
room.

The last query would be should I connect the screen ground up to mains
ground/earth in a neighbouring power socket which I'm guessing will
indirectly connect up to the amp chassis via power lead or should I not
worry?

NO!

all audio screens should be connected to equipment ground, never to
mains grounds


Worst case I suppose I can connect it up should there be an induced hum
or interference.


Other way, the hum will be if you DO connect it up.

Cheers
Pete



--
Religion is regarded by the common people as true, by the wise as
foolish, and by the rulers as useful.

(Seneca the Younger, 65 AD)

On Wednesday, 29 June 2016 11:14:00 UTC+1, Pet @ www.gymratz.co.uk ;¬) wrote:
On 28/06/2016 17:06, tabbypurr wrote:

Just want to be 100% sure as it's all going to be plaster boarded over
in the next few days so no access to it from then on.

Then look up the cable's capacitance and the source unit's output impedance.

I spent a long while trying to remember all that stuff back from my
Radio amateur years.

Ended up with some mad figures
The pre-amp outputs are 560 ohms

With 560R you can hang just about anything on it. Different story if it were 50k.

The closet cable I could find matched most of the numbers on the cable
outer but it had a few more twisted pairs. Mine is 4 x twisted pair with
aluminium screen and a screen ground/dump wire.

Capacitance was 50pf per foot (I think) and maximum length is about 12 foot.

Cable resistance is a nonissue here, as long as the sub is active, ie has its own power lead as well as signal in.

Just running it in now and it just fits in the trunking.

Running it past the first wall plate I've just broken 2 pairs out from
the bundle which will give me 2 more pairs to the opposite corner of the
room.

The last query would be should I connect the screen ground up to mains
ground/earth in a neighbouring power socket which I'm guessing will

no no no.

indirectly connect up to the amp chassis via power lead or should I not
worry?

worry about what?

Worst case I suppose I can connect it up should there be an induced hum
or interference.

no, that definitely won't solve it.


NT

On 29/06/2016 11:19, The Natural Philosopher wrote:

The last query would be should I connect the screen ground up to mains
ground/earth in a neighbouring power socket which I'm guessing will
indirectly connect up to the amp chassis via power lead or should I not
worry?

NO!

all audio screens should be connected to equipment ground, never to
mains grounds

OK. If needs be I'll run a wire out of the back box to the amp then.



Cheers - Pete