Lengh of cable limit when using a LDC mic?
- Thread starter AL P
- Start date
Bobbsy
Boring Old Git
Well, the real answer is that it depends on the quality of cable and the gear at either end. The LDC needs phantom power and, eventually, losses in the cable run will reduce the phantom voltage below what the mic needs.
However, the practical answer is that, in a home studio environment, there's no limit that will effect you. In a live sound situation it's not unusual for mic multicores to be 100 metres+ long without any problems. Five or ten metres in a typical home studio is, as a good friend of mine would have said, a mere bagatelle.
Now, if this was an UNbalanced feed (impossible on an LDC) the answer would be difference as outside interference becomes a real issue.
However, the practical answer is that, in a home studio environment, there's no limit that will effect you. In a live sound situation it's not unusual for mic multicores to be 100 metres+ long without any problems. Five or ten metres in a typical home studio is, as a good friend of mine would have said, a mere bagatelle.
Now, if this was an UNbalanced feed (impossible on an LDC) the answer would be difference as outside interference becomes a real issue.
thanks for the reply!..
the stunt (so to speak..LOL)..I`m looking to pull of, is going to require roughly 50-75ft of MIC cable..I`d be using a spirit folio 6 channel mixer 48V phantom power..their will only be the one mic..nothing else hooked to the board etc...my cables are`nt absolute top of the line, but they are almost brand new and in really good condition..hopfully they`ll pull it off..
the stunt (so to speak..LOL)..I`m looking to pull of, is going to require roughly 50-75ft of MIC cable..I`d be using a spirit folio 6 channel mixer 48V phantom power..their will only be the one mic..nothing else hooked to the board etc...my cables are`nt absolute top of the line, but they are almost brand new and in really good condition..hopfully they`ll pull it off..
Massive Master
www.massivemastering.com
If you can't get away with 300' of mediocre cabling, something is wrong with the cabling.
The limit is the acceptable HF loss.
For a nominal mic output Z of 200Ohms* the response will be 3dB down at 20kHz for a capacitive load of ~40nF.
If we have a worsecase cable capacitance of 200pf/mtr (and Canare starquad was just 162pf/mtr) that gives a maximum run of 200mtr.
But, many mics never get to 20kHz, certainly no dynamics of my aquaintance and in practice if you needed to drive 500mtrs of starquad you would use a high quality pre amp with a <50Ohm op Z!
*I know across the Pond the standard mic Z is 150R which gives you a bit more "reach" but in practice, never gonna tell.
Dave.
For a nominal mic output Z of 200Ohms* the response will be 3dB down at 20kHz for a capacitive load of ~40nF.
If we have a worsecase cable capacitance of 200pf/mtr (and Canare starquad was just 162pf/mtr) that gives a maximum run of 200mtr.
But, many mics never get to 20kHz, certainly no dynamics of my aquaintance and in practice if you needed to drive 500mtrs of starquad you would use a high quality pre amp with a <50Ohm op Z!
*I know across the Pond the standard mic Z is 150R which gives you a bit more "reach" but in practice, never gonna tell.
Dave.
witzendoz
Senior Member
Don't get him confused with mtrs of cable, he was talking about 75' which is only approx 22.9 mtrs. Which is nothing. Some of the mic runs in my studio are over 16 mtrs, 52', live I have had 40 + meters, 131'
No problems at all, however use good cable or the phantom will drop off volts very quickly.
Alan.
Bobbsy
Boring Old Git
I wouldn't worry. 75 feet won't be any problem at all.
FYI, my STANDARD run in my home studio is 30 metres/100 feet, simply because that's my shortest multicore and it's easier to use that rather than a bunch of separate mic cables. My set up involves one spare bedroom as my control room and another spare bedroom (across and just up the hallway) as the "studio". The actual run could easily be handled by 10 metre cables but it's just easier with the multicore since I have to strip everything out at the end of every session.
Armistice
Son of Yoda
How many spare bedrooms have you got there Bobbsy? Does your wife had a spare bedroom or two for her hobbies as well, or have you snagged them all?
Bobbsy
Boring Old Git
How many spare bedrooms have you got there Bobbsy? Does your wife had a spare bedroom or two for her hobbies as well, or have you snagged them all?
You caught me out. What I refer to as my control room my wife would call "the art room" because her easels and canvases are in there. It might be stretching it a bit to call the canvases HF absorbers but I can try to get away with it!
As for the studio, at certain times that's called "the guest room". It's amazing what a good bass trap the futon mattress makes when stood in the corner!
Phantom power loss is a red fish.
Mogame pt no W2971 has 24AWG conductors and a loop resistance of 0.18Ohms per metre (0.054R/foot. You imperialist can do your own math!).
That works out to 180 Ohms per kilometre! Spook juice comes via effectively 3.4K so 50 Ohms or so for even long "normal" runs is not going to matter diddly.
Justfort: "Back in the day" we used to run 30 Ohm dynamics on unscreened clear twisted mains wire and a mic 1/2 mile away was quite common. (into valves via 1:100 traffs.)
Dave.
Mogame pt no W2971 has 24AWG conductors and a loop resistance of 0.18Ohms per metre (0.054R/foot. You imperialist can do your own math!).
That works out to 180 Ohms per kilometre! Spook juice comes via effectively 3.4K so 50 Ohms or so for even long "normal" runs is not going to matter diddly.
Justfort: "Back in the day" we used to run 30 Ohm dynamics on unscreened clear twisted mains wire and a mic 1/2 mile away was quite common. (into valves via 1:100 traffs.)
Dave.
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