Why Gotham Cable?
We got a request recently from a good customer who owns a FAR 47 Gold Special Edition microphone. He wanted a better microphone cable to go with this very high quality mic. I had to agree with him. The cables supplied with most mics from China are just adequate and the connectors can be noisy and un-reliable. He had done some research and suggested we take a look at Gotham Audio Cable.
After doing my own research what I found with Gotham Audio was a Swiss (think precision) company that comes from the noble tradition of building audio cable for the greats, including Neumann. Their seven conductor microphone cable has been designed specifically for the job of powering a tube microphone and bringing the audio back safe and protected from evil clutches of noise and high frequency losses.
Below is a brief explanation of why is it so good for your tube microphones.
Gotham tube mic cable. The Red & Blue wires are for high current
You can see in the photo above the way the double shielding is made of extremely fine wire. This keep the cable flexible even with two shields. Also notice how they are double wrapped in opposite directions. They are both considered to be 100% shields but with two of them there is absolutely no way electrostatic noise or Radio Frequency Interference (RFI) is getting into your mic sound!
The Poly-ethylene insulation on the wires is made thick which keeps the capacitance low. Between conductors you are talking about 90nF per Kilometre! (Kilometre is 6/10 of a mile) so that is only 9 pico Farads per Meter of cable. ( 1 Metre = 39") That means on our 7 meter cable (22' long) there is only 63 pF between the two wires that carry the sound. (those are the ones that matter )
The capacitance between the conductors and the shield is another 16pF/metre so altogether we have 63+(16*7)= 175 pF of capacitance on a 7 Metre cable.
On a 1,500 ohm preamp input that amount of wire capacitance would just start to affect the signal on those wires at a frequency of about 70,000 Hz! Over six times beyond the highest frequency of human hearing. Unless you are recording Bat calls that's not going to matter.
The whole assembly is protected by a jacket made of strong PVC rubber.
I should tell you now you can have any colour you want, as long as it is Charcoal Grey. :-)
Heavy Duty Filament Conductors make a difference
Running the filament in your tube mic at the right temperature allows electrons to flow off of the cathode freely. Too little current in the filament means it is not hot enough and the tube does not operate properly. This affects the sound.
The Gotham cable we use has two heavier gauge conductors. We use one for the Ground lead and the other one to feed the 6.6 volts from the power supply up to the tube. If you use a mic that uses both Triodes like an APEX 460 or a Nady 1050, the current needed is about .3 Amps. (300mA) If you use small wires over 25' (8 M) you can loose as much as .9 volts with cheap cable. I have measured this very thing with some tube mic cable. So what started as 6.6 volts in the power supply is now only 5.7 volts at the microphone! The tube wants to get 6.3V nominally. With our TMC-7 22' (7M) cable we see a voltage of 6.38 at the tube of our m251 Standard Model, which uses the 6072 dual triode CCDA circuit.
And if your mic uses a 6922 tube (ECC88), as used in some Rode tube mics or our FAR 47 SE which suck up even more filament current, you need this cable even more.
We have two versions of this fine audio cable complete with Neutrik black, 7 Pin, gold plated connectors
FAR TMC-5 15 Ft (5M) for $95.00
FAR TMC-7 22 Ft (7M) for $105.00
Custom lengths available on request.
To place your order for a professional Tube microphone cable, just send us an email to: brian.fox@foxaudioresearch.ca
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