Reporter's Notebook

The art and science of the interview

Gear 2.0

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Mixer and Inline Patch Setup

I’ve written about gear and gear related frustrations before here, here, here, and here.  I’ve been through three mixers, two phone patches, a half dozen visits by the phone company and a number of wiring configurations on the way to where I finally am today.  That place is interviewing happy land.  Through two years of trial and error, I’ve reached a point where the telephone interviews I conduct (1) have no line noise, (2) can be heard by the person I’m talking to, (3) have audio levels between us that are balanced and (4) uses a setup configuration that makes sense.  If you’re doing telephone interviews, each of these is important but radically different from the other.  I’ve found lots of stuff online that was, to some extent, helpful.  So I want to give some advice and some help back.

(1) No line noise means just that.  I think when most people use the phone, they only notice line noise like scratching or hum when its obvious.  But when you’re doing interviews and there are moments when the guest is responding to a question, there can be long seconds of silence.  That is where you’ll hear even the quietest hum and that is the sign of a substandard setup.  Hum can be caused by transformers too close to gear inside the house.  But make sure you have the phone company check the wiring and the line to make sure it isn’t them.  A shorted wire can cause it.  Maybe your old 4-strand wiring needs to be replaced with Cat-5 or higher wiring.  Also some lines are just noisy and you can ask the phone company to install on your line an industrial version of the little transformer that is at the end of many older USB cables.

(2) Being heard by the other person has a lot to do with how well the telephone patch separates your voice from who you’re talking to.  I’m no expert at this, but I’ve learned that before a mixer can do you any good, meaning before you can put your voice on one channel and the caller’s voice on another, the phone patch has to split them.  It does this with something called a digital hybrid circuit.  And once the call gets to your mixer, the mixer has to employ something called mix minus, meaning your own voice doesn’t get fed back to the line.  If it does, it gets cancelled and that can contribute to the third problem, equal audio levels.

(3) I can’t tell you how many times I’ve had an interviewee tell me they can’t hear me very well.  I sound like I’m far away.  I sound like I’m in a box.  This is because digital hybrids also differ in how loud each side of the call (caller v called) is.  Most have a 20db difference between the two, meaning the caller is going to be louder than you going into the mixer.  And even if the hybrid has split the call and the mixer has each side on a different channel, the mixer can’t compensate for the difference.  You have to have a hybrid that lets you control levels on both sides of the call so you can adjust them manually.  For reference, an increase of 3db means the audio just doubled in intensity.  So imagine how quiet a reduction of 20db can be.

(4) The mixer I started with was tiny.  It didn’t have a lot of the extra jacks I needed to give me the flexibility to control aspects of the call.  The next mixer had more jacks, but honestly, I didn’t know how to use them.  And let me tell you, looking for help either online or in gear stores was futile experience.  Audio stores like, for instance, Guitar Center, know mixers for recording bands.  They know nothing about configurations for broadcast, podcast or telephone interviews.  So when I showed them a block diagram I drew as a way to try to understand why my interviews were so poor, they couldn’t help.  After months and months of switchiing out gear and switching around cables, I finally stumbled upon a setup that works perfectly.  And that also means I don’t have three or four sliders up or a handful of pots turned in crazy ways.  I took a picture of the setup so I can never screw it up.

Now, for the help. If you’re doing telephone interviews for broadcast or podcast, I’ve discovered there are lots of ways to record phone calls.  The easiest seems to be with Google Voice.  Then, there are a number of digital plug ins you can use with mobile devices.  Me, I think the Plain Old Telephone System is going to be around for a little while longer, and since I’m not that enamoured with VOIP, I’m sticking with analog.  So, if you are too, here’s what I’m using:

– JK Audio Telephone Inline Patch (Less expensive than the Broadcast Host and does almost everything BH does for $200 less. Has 40db rather than 20db separation.  Apparently, more is better).
– PROFX8 Mixer with USB
– Shure SM7B Microphone

But the most valuable thing you need is someone to tell you if you setup works before you’re on the line with an important interviewee who can’t hear you.  That means you need a caller to call.  But I can tell you people get annoyed quick if you call them over and over and over, which is what you need to do the test your gear and check your setup.  So, I suggest you use something called “Tell Me” (408-752-8052).  Tell Me is a voice activated service that can deliver sports, weather, news and much more over the phone.  It works by voice command.  And because it works by voice command, that means it knows what a voice at proper volume should sound like.  So you can call it to check your system.  Talk through your microphone, through your mixer, through your phone patch, to Tell Me.  If something is wrong, you’ll figure it out quickly.  It’s not a free service, but its per-minute rate is not overly expensive.

And even though, as I said earlier, there isn’t much online that can help (even many of the YouTube videos weren’t specific enough), this instruction sheet from BSW was helpful – http://www.bswusa.com/assets/pdf/BSW_HowTo_BroadcastHost.pdf

I’m glad to say I think this is my last post about gear problems for awhile.  Yaaaaay!

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