Low capacitance audio coax
 

I need to send an audio signal from a 50K ohm source over a distance of
a couple of feet in a screened cable. However, most audio coax seems to
be about 100pF/ft so 2ft of this and 50K will turn over just below
16KHz. So, anyone know a source of low capacitance audio coax?

Cheers

Ian

Low capacitance audio coax
 

"Ian Bell" wrote in message
...
I need to send an audio signal from a 50K ohm source over a distance of a
couple of feet in a screened cable. However, most audio coax seems to be
about 100pF/ft so 2ft of this and 50K will turn over just below 16KHz. So,
anyone know a source of low capacitance audio coax?


**Use a buffer first. A 50k Ohm source is stupidly high. A high quality
buffer can be assembled for a few pennies.

If you must persist in using broken equipment, you could look at a variant
of RG59/U coax. Capacitances figure range from 50pF ~ 70pF/Metre. Belden
have a cable called 1192A, which exhibits around 40pF/Metre.

Use a buffer. MUCH smarter.


--
Trevor Wilson
www.rageaudio.com.au

Low capacitance audio coax
 

Trevor Wilson wrote:
"Ian Bell" wrote in message
...
I need to send an audio signal from a 50K ohm source over a distance of a
couple of feet in a screened cable. However, most audio coax seems to be
about 100pF/ft so 2ft of this and 50K will turn over just below 16KHz. So,
anyone know a source of low capacitance audio coax?


**Use a buffer first. A 50k Ohm source is stupidly high. A high quality
buffer can be assembled for a few pennies.


You assume too much.

If you must persist in using broken equipment, you could look at a variant
of RG59/U coax. Capacitances figure range from 50pF ~ 70pF/Metre. Belden
have a cable called 1192A, which exhibits around 40pF/Metre.

Use a buffer. MUCH smarter.



Again, you assume too much.

Cheers

Ian

Low capacitance audio coax
 

"Ian Bell" wrote in message
...
Trevor Wilson wrote:
If you must persist in using broken equipment, you could look at a
variant of RG59/U coax. Capacitances figure range from 50pF ~ 70pF/Metre.
Belden have a cable called 1192A, which exhibits around 40pF/Metre.

Note that the requirement was stated in feet (2) and the figures given are
for meters, which are about 3 feet. Divide Trevor's numbers by 3 and you
will instantly find a more satisfactory number for your application.

Low capacitance audio coax
 

Trevor Wilson wrote:
"Ian Bell" wrote in message
...
I need to send an audio signal from a 50K ohm source over a distance of a
couple of feet in a screened cable. However, most audio coax seems to be
about 100pF/ft so 2ft of this and 50K will turn over just below 16KHz. So,
anyone know a source of low capacitance audio coax?


**Use a buffer first. A 50k Ohm source is stupidly high. A high quality
buffer can be assembled for a few pennies.

If you must persist in using broken equipment, you could look at a variant
of RG59/U coax. Capacitances figure range from 50pF ~ 70pF/Metre. Belden
have a cable called 1192A, which exhibits around 40pF/Metre.


1192A is 40pF per foot not per metre.

Cheers

Ian

Use a buffer. MUCH smarter.

Low capacitance audio coax
 

"Ian Bell" wrote in message
...
Trevor Wilson wrote:
"Ian Bell" wrote in message
...
I need to send an audio signal from a 50K ohm source over a distance of
a couple of feet in a screened cable. However, most audio coax seems to
be about 100pF/ft so 2ft of this and 50K will turn over just below
16KHz. So, anyone know a source of low capacitance audio coax?


**Use a buffer first. A 50k Ohm source is stupidly high. A high quality
buffer can be assembled for a few pennies.


You assume too much.

You have supplied so little information about what it is that you are doing
that all we can do is make assumptions, and Trevor's assumption seems
perfectly reasonable to me. Unless you want to tell us why it isn't.

I had been going to answer your original post to the effect that "I wouldn't
start from here" (ie, wouldn't try to send audio from a source with as high
an impedance as 50K)

No *audio* co-ax will have as low a capacitance as you think you want. Try
looking at RF co-ax instead.

David.

Low capacitance audio coax
 

"David Looser has roos loose in his top paddock"


I had been going to answer your original post to the effect that "I
wouldn't start from here" (ie, wouldn't try to send audio from a source
with as high an impedance as 50K)


** Shame about all the millions of MM pick-up cartridges that seem to work
OK.

Not to mention electric guitars that use 500kohm volume and tone pots.



..... Phil

Low capacitance audio coax
 

"Trevor Wilson"

Belden have a cable called 1192A, which exhibits around 40pF/Metre.


** Quad core, low Z mic cable ????




...... Phil

Low capacitance audio coax
 

Ian Bell wrote:
Trevor Wilson wrote:
"Ian Bell" wrote in message
...
I need to send an audio signal from a 50K ohm source over a
distance of a couple of feet in a screened cable. However, most
audio coax seems to be about 100pF/ft so 2ft of this and 50K will
turn over just below 16KHz. So, anyone know a source of low
capacitance audio coax?

**Use a buffer first. A 50k Ohm source is stupidly high. A high
quality buffer can be assembled for a few pennies.

If you must persist in using broken equipment, you could look at a
variant of RG59/U coax. Capacitances figure range from 50pF ~
70pF/Metre. Belden have a cable called 1192A, which exhibits around
40pF/Metre.


1192A is 40pF per foot not per metre.

**Mea culpa. Stupid Farnell. Stupid me. Most of their cables are listed in
XXpF/Metre, except that one.

Use a buffer.


--
Trevor Wilson
www.rageaudio.com.au

Low capacitance audio coax
 

Ian Bell wrote:
Trevor Wilson wrote:
"Ian Bell" wrote in message
...
I need to send an audio signal from a 50K ohm source over a
distance of a couple of feet in a screened cable. However, most
audio coax seems to be about 100pF/ft so 2ft of this and 50K will
turn over just below 16KHz. So, anyone know a source of low
capacitance audio coax?

**Use a buffer first. A 50k Ohm source is stupidly high. A high
quality buffer can be assembled for a few pennies.


You assume too much.

**Nope. Just the facts. Buffers can be installed for not much money.


If you must persist in using broken equipment, you could look at a
variant of RG59/U coax. Capacitances figure range from 50pF ~
70pF/Metre. Belden have a cable called 1192A, which exhibits around
40pF/Metre. Use a buffer. MUCH smarter.



Again, you assume too much.

**Such as?


--
Trevor Wilson
www.rageaudio.com.au