Gear / Technical Help > Microphones & Setup

Trade offs of using active cables?

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checht:
I'm saving to get a set of active cables with PFA's for use with Schoeps mk4's and wonder if anyone has info on what, if any, downsides there are to going this route?

I imagine there might be more susceptibility to rf and other interference, as I think the actives are unbalanced.

Would this be more or less of an issue when recording loud rock shows?

Anything else to consider when deciding whether to use actives or not?

Many thanks,
Chris

bobby bourbon:
When I got mine, Jerry Bruck told me (and I talked to that man for more hours than I care to admit and he would care to remember) the only problem I may encounter was if they were placed too close to lighting. This was right when the balanced CCM was made available. He said if I was going to record in close proximity to lighting, I *may* experience problems with noise He didnt suggest in any way I should count on it. I guess now there are more radio waves than there were. If you think that may be a problem, you can put a join in your cable. That can help in carrying too. The majority of times Ive used the schoeps was with a length of roughly 6'.  I clip the remaining 10' on only when necessary. If the cable is put together with no compromise in quality at the join it should not make a difference and will add good benefit. This pictures nice.  I was looking for something from the white house and found this. This was the last bug found. Cant see it in preview but hopefully it shows up.

goodcooker:

I've never had any problems with interference when using active cables for Schoeps, Neumann or AKG.

Only problem I had was dealing with the cables themselves - they like to kink up and I like to keep the capsules attached - so every so often I take the capsules off and unwind and rewrap them to straighten them out.

Not long ago I was recording stage lip and a musician moved one of the monitors on top of  my cables running along the edge of the stage. It cut right through it. Most active cables - especially the nBob cables I use for Schoeps are far more delicate than most cables. The remote cables I have for the MBHOs are much more robust and they are techflexed.

Always remember to run your cables perpendicular to lighting and power cables - meaning if you have to get any where near them to cross them at 90 degree angles - never run your cables parallel to lighting or power runs!

DSatz:
The original Schoeps active cables were designed to be supple. Maybe 20 years ago Schoeps changed over to Kevlar-reinforced insulation, which put a real damper on the cables being cut through accidentally. I cycle through my Schoeps equipment every 15 years or so and send it to the factory for checkout, so over time my older active cables have been updated, and I'm glad about that.

--There definitely are more RF sources in the picture than there were in 1973-74 when the Colette series was introduced. The transmitters (a/k/a cell phones) typically operate at higher frequencies than were common in those days, and use signalling systems that produce "edgier" sounds if those signals are picked up and converted to audio (= "detected"). But the main controlling variable (other than transmitter power, of course) is the proximity of the transmitting device to the point(s) of entry and detection in the circuitry. If someone puts a cell phone or pager directly onto your mike cable while you're recording, even a completely balanced system can be subject to audible interference.

It's a "relative" situation with numerous variables. Jerry's right that CCMs are preferable to the modular Colette series if you know that RFI is likely to be a particular problem. But that has to be weighed against the Colette system's interchangeable capsules and active accessories, which the CCM series doesn't have. To me the modular approach still seems essential for most applications, while the CCMs still feel to me like they're for more certain specific applications (e.g. fixed/installed systems). I'm biased, though, because I bought in (literally!) to the modular system early on, and took advantage of its wide range of options. If Schoeps put the CCM amplifier circuitry into a tiny modular package that allowed interchangeable capsules (even without the extra connection needed for active accessories), I'd buy four of them in a flash.

I live in New York City, have used Schoeps microphones to record perhaps 2,500 live concerts and other events (fairly often with active accessories--I use active cables but also active extension tubes sometimes), have heard RF in my recordings only once ever that I can recall, and that was with microphones of the older CMT series (discontinued in the 1970s/80s). That was before cell phones existed, but in the heyday of "citizen's band" (CB) radio. A taxi driver drove by, presumably with an illegal booster amplifier in the trunk. Those could go up to 1000 Watts, and being illegal, they weren't tested and type-approved by the FCC, nor professionally installed for the most part; "dirty" (spurious out-of-band) signals were common. Still, the interference lasted only a few seconds.

In more recent years I've recorded many opera productions with capsules suspended from the balcony of a downtown church on 10-meter active cables instead of the usual 5. By then nearly everyone in the audience had cell phones, and there was never any problem with RF pickup. But those capsules and cables were 10+ feet above the audience's heads--and as I said, that distance matters greatly. Put a transmitter close enough to almost any circuit and you'll get interference.

ArchivalAudio:
Thanks to DSatz for that explanation.
I'd also go back to note about the lighting cables:  To say that anytime you run a mic cable balanced, shielded or otherwise if it is going to cross, and touch or be in close proximity be sure it crosses at the intersection at 90° this will halp to eliminate the possibility of 60hz (or 60 cycle per second) hum or buzz that can occur when a mic cable crosses a power cable. Though this has nothing to do with RF interference, but introducing hum , buzz or noise.

If you get PFA's get the longer "extended" barrel, which can supply up to 60 v, and also help to eliminate any RF interference because of the shielding in the units.
http://naiant.com/studio-electronics-products/inline-devices/pfa-phantom-power-adaptor/

--- Quote ---The PFA is available in both standard and extended XLR barrel connectors. The extended version fully shields the circuit, with a total length including boot of 100mm. The standard version length including boot is 70mm. The extended version may be preferred in difficult EMI environments. Both barrels will directly connect to any phantom-powered XLR input.

The extended length barrel may also contain a circuit to generate up to +60V polarization voltage required for certain "active" remote capsule microphones. The polarization voltage will be regulated to the voltage specified by the microphone's manufacturer. With this option, the PFA will generate the required voltages for the "active" microphone system with a phantom power supply of at least +16V.
--- End quote ---

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