Which is recommended a twisted pair with or without shield to carry line level signals to 4-5 feet distance or is the Coax ?
I have bought few coax cables before but they all are very rigid due to the kind of shielding and it is hard to wire PCBs with them. ( for short distances ). Also looking for a flexible ( very) shielded coax too.
I have bought few coax cables before but they all are very rigid due to the kind of shielding and it is hard to wire PCBs with them. ( for short distances ). Also looking for a flexible ( very) shielded coax too.
Always use a shielded cable for interconnects. Another worth considering is star quad. For short distances in a screened enclosure where it's difficult to use shielded wire you could tightly twist the wires
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Shielded (i.e. coax) for unbalanced. Twisted pair for balanced, ideally shielded too. As scottjoplin says, you can often get away with twisted for short unbalanced connections inside a unit.
Thanks Guys. I am looking for something to connect between DAC-pre amp - amp. Which will be the least hefty coax cable that will work in 3-4 feet distance? I bought a couple but they are pretty rigid so take much more length than needed as they can't loop in short radius .
better audio RCA cables may be more flexible than coax intended for RF
Mogami, Blue Jeans, Pro distributers should have cables with pF/m, shield construction speced, 360 degree termination, sometimes even Belden part # for the coax
for unbalanced signal in coax shield/return resistance should be as low as practical
Mogami, Blue Jeans, Pro distributers should have cables with pF/m, shield construction speced, 360 degree termination, sometimes even Belden part # for the coax
for unbalanced signal in coax shield/return resistance should be as low as practical
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Low capacitance is also important for me as I don't have an active pre amp.
Also what RG type cables are the one should search for more flexibility and smaller loops etc?
Also what RG type cables are the one should search for more flexibility and smaller loops etc?
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For maximum flexibility a thinnish microphone cable may be best, this one from van damme looks quite good Van Damme Pro Grade Classic XKE flexible 1 pair, per metre | VDC Trading
Hi,
for a Coax cable 3.8mm diameter is rather thin.
Even thinner is the SommerCable SC-Cicada-SO-D14 at 2.6mm dia.
It's quite flexible with two stranded copper conductors, a spiral copper shield and a tinned drain wire.
The latter feature makes it easy to handle, as You don't need to unfold and solder the shield, but just cut it off and use the drain wire for shielding.
For RCA connect together the drain wire and one of the inner conductors for lower gnd resistance.
jauu
Calvin
for a Coax cable 3.8mm diameter is rather thin.
Even thinner is the SommerCable SC-Cicada-SO-D14 at 2.6mm dia.
It's quite flexible with two stranded copper conductors, a spiral copper shield and a tinned drain wire.
The latter feature makes it easy to handle, as You don't need to unfold and solder the shield, but just cut it off and use the drain wire for shielding.
For RCA connect together the drain wire and one of the inner conductors for lower gnd resistance.
jauu
Calvin
where does the impedance rating for cables falls in selection? does it matter if it is a 50Ohm vs 92Ohm
a] The ancient RG Type # doesn't tell us much for audio applications.
Only the Radio Frequency Characteristic Impedance, the overall diameter and maybe the center conductor size.
b] Radio Frequency Characteristic Impedance has nothing to do with analog interconnect cables.
c] Radio Frequency Characteristic Impedance is important in longer digital cables, but not so much in shorter cables.
d] Good RCA unbalanced interconnects are always coax.
e] XLR balanced interconnect cables are mostly Shielded Twisted Pair (STP).
Some pros are now using Cat5 cables (unshielded or shielded) but there is a lot of fie print that goes with this setup.
Sometime in harsh electrical noise conditions, shielded Star-Quad is used.
f] The coax used for RCA interconnects should have a heavy braided shield.
g] The RG-6 coax in the cable TV installers truck is optimized for very high TV frequencies. Not some thing that you would want to use for analog audio.
Only the Radio Frequency Characteristic Impedance, the overall diameter and maybe the center conductor size.
b] Radio Frequency Characteristic Impedance has nothing to do with analog interconnect cables.
c] Radio Frequency Characteristic Impedance is important in longer digital cables, but not so much in shorter cables.
d] Good RCA unbalanced interconnects are always coax.
e] XLR balanced interconnect cables are mostly Shielded Twisted Pair (STP).
Some pros are now using Cat5 cables (unshielded or shielded) but there is a lot of fie print that goes with this setup.
Sometime in harsh electrical noise conditions, shielded Star-Quad is used.
f] The coax used for RCA interconnects should have a heavy braided shield.
g] The RG-6 coax in the cable TV installers truck is optimized for very high TV frequencies. Not some thing that you would want to use for analog audio.
I don't feel you need that low of a cable capacitance for the lengths you are needing. Shoot for 30~40 pf/ft, measured centre to shield.
Coax will always have a certain minimum capacitance; their very construction simulates a capacitor. The smaller the cable diameter, the more it looks like a capacitor.
If you want your audio interconnects to do double duty as digital interconnects, use 75 ohm crimp connectors (Such as Canare RCAP-C, not expensive, and a suitable crimper can be had for perhaps $40; the Canare one is pretty pricey) and make them the correct length for minimal reflection (I don't remember the length off the top of my head, but you can Google it).
Seek high quality dielectrics; unfortunately PTFE is inherently stiff, but foamed dielectrics can work well. Be careful with handling; Coax in particular is sensitive to small bends. Strictly adhere to the minimum bend radius specification of the raw cable.
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For analogue audio use, the RF impedance tells you the cable capacitance. This is because Zrf=sqrt(L/C) and Vrf=sqrt(1/LC). You can assume Vrf = 2/3 c for solid dielectric cables i.e Vrf=2 x 10^8m/s. So C (per m) = 1/(Zrf Vrf). For 50 ohms this is 100pF/m.
Coax of a particular RF impedance and particular dielectric will always have exactly the same capacitance however thick or thin it is.Johnny2Bad said:
It might be simpler for our Original Poster (OP) if we say dielectric outer diameter affects characteristic impedance, and given identical dielectric constant, alters coaxial cable capacitance.
Similarly, given identical dielectric outer diameter, and differing dielectric constant (different dielectric material), characteristic impedance varies, which alters coaxial cable capacitance. Obviously if both change, capacitance also changes.
In practical terms for this application, reducing the dielectric outer diameter raises capacitance; moving to a lower dielectric constant lowers capacitance. So he should seek high quality dielectric material if the goal is lower cable capacitance, and will sacrifice capacitance if he seeks smaller diameter cable.
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