Rating
Dynamic Microphone Preamp
Dynamic Microphone Preamp
AUDIO – CONTENT VS. QUALITY
In 1997, musician James Taylor, and his recording engineer Frank Filipetti, won a Grammy Award for best engineered album “Hourglass”. The big surprise was that this album was recorded in James Taylor’s living room. The explosion through the recording industry could be heard around the world. Now anyone could produce a ‘world class’ recording virtually anywhere.
Of course, the CD produced in the band’s garage is nothing new. It only proves that “content is king”. But perhaps we should add a corollary to that: “Content is king, and quality makes it sell.” In these days of MP3 players and low-bit rate downloads, it is amazing what low quality levels are acceptable to many listeners. But, even if we assume that 20% of the audience will listen regardless of the quality, that leaves a lot of audience who might also listen if the quality of the material, and the quality of its delivery, improved.
So quality still matters. It’s just that getting to that top level is now a lot easier (and a lot cheaper) than it used to be. Just note that condenser microphones, that a decade ago were rarely available below US$1,000 are now routinely available for US$199 or even less.
Are they the same? No, of course not. The question really is, can that $199 model be good enough for your project? Will it last on the road with abuse it might get? How well does it work outdoors as well as indoors? And a thousand similar questions. You might well end up back at the $1000 model just because you can’t afford to have a mic fail during your next recording or stage performance.
And this also applies to the cable between that microphone and the preamp or mixer. And don’t be confused: microphone cables, or any other cable, is just as technologically advanced as the device it is plugged into. And, like links in a chain, your signal quality is limited only by that weak link. And if that weak link is cable then, shame on you, because that’s the cheapest link to fix. You just have to know what to choose.
For analog microphones, there are really three basic choices: ruggedness, low noise, and performance. We’ll look at the first two of these factors and determine just what that cable would look like. The third, performance, will be the subject of a following column.
RUGGEDNESS
The most rugged microphone cables currently are made with rubber. These are very rare cables. You might think the cables you are currently using are made with rubber. It is very likely you would be wrong. There are formulations of PVC that look and feel like rubber, but are nowhere near as rugged. If you want to know for sure, just check with the manufacturer. You can also do a simple test. Get three feet of rubber-jacketed cable (such as Belden 8412) and tape three feet on a floor. Next to it tape three feet of any other cable you wish. Now find an office chair with metal wheels and go over these cables, back and forth, for a few minutes. If you know someone considerably heavier than you, have them go back and forth as well.
After this “torture test” un-tape the cables and look at them. Will you be surprised! The rubber cable is almost indestructible, while the PVC or other plastics, can get shredded quite easily.
LOW-NOISE
This can mean different things to different people. There is ‘shot noise’ also called ‘impact noise’ that is a common problem with guitar cables. However, that kind of noise is much rarer with professional balanced-line twisted-pair microphone cables. And the reason it is rare, is that the impedance of most professional microphones is very low, around 150 ohms, compared to guitars which are very high, up to 50,000 ohms.
More often, with mic cables, “noise” refers to EMI (electromagnetic interference) or RFI (radio frequency interference) which can easily work its way into the cable and interfere with the audio, or worse, work its way into the preamp, mixer, or console using the mic cable as a really nice “antenna”.
The way to reduce this effect is first, to run the twisted pair as a balanced line. This is what all professional audio devices already do. An explanation of balanced lines, with common-mode noise rejection, would take an entire column, and more. Goggle those terms out if you want to learn more. And one of the things you will find is that the ideal twisted pair has two wire very close to each other. (Wires close together make the noise on each wire as close to identical as possible.) This is one reason why we twist the two wires in a twisted pair, to keep them close together.
However, when you bend and flex this mic cable, the two wires in the twisted pair tend to untwist slightly. This makes them vulnerable to EMI and RFI, or to leak out the audio signals running on them to cables around them. There are two solutions to this problem.
The first solution is a very new solution and it is to stick the two wires together when they are being twisted. There is only one cable made like this, and that is Belden 1353A. It is, in fact, a single pair “data cable”, a single pair Category 5e computer cable. Now a computer cable installer would say this is crazy to have a “one-pair Category 5e data cable”, but now you understand it perfectly. If you can stick the two wires together, then no matter how you bend and flex the cable, they will stay right next to each other, and give you maximum noise rejection. In fact, the noise rejection is so good that this pair isn’t even shielded. Just stick the two wires into pins 2 and 3 inside the XLR microphone connector, and it will work just fine…with one exception. And that exception is microphones that are powered through the mic cable, “phantom powered” microphones. They need that shield to help deliver the power to run the microphone. Obviously, this unshielded cable won’t work there. But for all the self-powered microphones, dynamic, ribbon, and other designs, this cables would be an excellent choice.
The second way to reduce EMI and RFI is to have a special construction with not a single twisted pair, but four wires, something commonly called “starquad”. If you open up this cable, you will find that the four wires are in one spiral (not two twisted pairs). To use this cable, you must combine the two wires opposite each other. This then turns four wires into the two wires for your connector (pins 2 and 3 again). These starquad cables also have a shield that connects to pin 1.
How starquad gives you ultra-low-noise performance would take another entire column, but suffice it to say that the performance of this design, especially at EMI – low frequencies – is dramatic. It is especially good at 50 Hz power noise. So if you must hang microphones from a lighting grid, for instance, starquad would assure minimum 50 Hz pickup in each mic line. Just be sure that the mics themselves are resistant to 50 Hz interference.
About the Author
Steve Lampen has been with Belden for 19 years and currently is Multimedia Technology Manager and Product Line Manager for Entertainment Products. He has an FCC Lifetime General License (formerly an FCC First Phone License) and is a BICSI Registered Communications Distribution Designer. His latest book “The Audio-Video Cable Installer’s Pocket Guide” is published by McGraw-Hill.
Visit our web site www.beldenapac.com or email us info@beldenapac.com
12AY7 Mic Pre – Video by Au Revoir Simone – Class A Tube Microphone Preamp
|
|
HDE (TM) Mini 3.5mm Voice Microphone for PC Laptop Skype $0.42 This is an ultra-portable Mini Microphone. It uses a standard 3.5mm jack, and is Plug and Play: no software to install! It’s an excellent addition to your laptop or notebook setup, & is suitable for internet telephony applications like VOIP or Skype. Talk to anyone, anywhere! Microphone settings are adjusted from your PCs audio control panel. Sensitivity: -54±3dB Frequency Range: 100-5KHz Direct… |
|
|
VideoSecu High Sensitive Preamp Microphone Kit for Security Audio Sound Voice Monitoring Recording Free 50 Feet Cable, Power Supply and Warning Decal WE6 $24.99 Collect audio evidence as important as capturing video evidence, this preamp microphone kit is a perfect addition to any video security camera system. This high gain mini preamp and microphone is the best for CCTV professionals, with Preamplifier IC built on board, it increase a microphone’s low output voltage to a stronger, more usable level, it features low noise, high gain and auto level adjust… |
|
|
Line 6 POD Studio UX1 $149.00 Killer guitar-recording rig, killer amps, pleasant price! By now you’ve heard how great Line 6′s amazing amp models are. Now, you can plug your guitar or bass right in — along with a mic, if you like — and record jaw-dropping tracks with ease! The POD Studio UX1 puts a handy and compact USB interface right on your desktop. You get ultra-low latency monitoring plus the inputs and output… |
|
|
Blue Microphones Icicle XLR to USB Mic Converter/Mic Preamp $41.94 Why should you bother with a bulky interface, when all you want to do is plug a single microphone into your computer? With a Blue Icicle in your arsenal, you can turn any microphone into a totally streamlined, USB-ready recording device. Instead of lugging around some fancy rack and a bunch of outboard gear, just toss an Icicle and a mic in your laptop bag, and take your studio straight to the sou… |
|
|
Preamp – Dynamic Microphone Pre-Amp (Fully Assembled) This microphone pre-amplifier is designed to work with dynamic microphones. It will amplify the signal from the microphone to a much higher level, enough to be able to connect it to the input of any audio amplifier with standard input sensitivity like ou… |
|
|
Dynamic Microphone Pre-Amp (Kit) … |
|
|
Clarion CX501 Double-DIN CD/Bluetooth/USB Receiver $299.99 DOUBLE-DIN BLUETOOTH CD/USB/MP3/WMA RECEIVERCD/USB/MP3/WMA PLAYBACKBUILT-IN BLUETOOTH INTERFACE (HFP HSP OPP PBAP A2DP AVRCP)BUILT-IN MICROPHONE728 COLOR VARIABLE LIGHTING DISPLAY & BUTTONSSIRIUS DIRECT CONNECT READYHD RADIO READY WITH OPTIONAL THD30150W X 4 BUILT-IN AMPSUBWOOFER VOLUME CONTROLBUILT-IN HIGH & LOW-PASS FILTERSMAGNA BASS EX DYNAMIC BASS ENHANCEMENTPARAMETRIC EQUALIZERBEAT EQ FOR SOU… |
|
|
JVC KW-XR810 4 x 50 Watts Dual USB/CD Receiver $299.95 JVC’s double-DIN KW-XR810 is a USB/CD receiver with plenty of connectivity–connect USB devices and iPod/iPhones using dual USB ports, or other devices using the front-panel 3.5mm auxiliary input. Bluetooth technology gives you hands-free audio or audio streaming with your cell phone, and expansion options include three preamp outputs and the easy addition of HD or satellite radio. The icing on th… |
|
|
Clarion NX501 6.2 Double-DIN Navigation Multimedia Control Station $999.99 Clarion’s NX501 offers all the features of the NZ501 in a 2-DIN package–a premium audio/video navigation unit with built-in GPS navigation, built-in Bluetooth for hands-free calling and audio streaming, and USB, iPod, and iPhone compatibility. iPod video playback is also available using an optional cable (CCA748). The unit is also Sirius Satellite Radio and HD Radio Ready (including the iTunes … |
|
|
Audio Technica AT2020 Side Address Cardiod Condensor Studio Mic $169.00 The price/performance standard in side-address studio condenser microphone technology, Audio Technica’s AT2020 studio mic has a low-mass diaphragm that is custom-engineered for extended frequency response and superior transient response. With rugged construction for durable performance, the microphone offers a wide dynamic range and handles high sound pressure levels (SPLs) with ease. Ideal f… |
Have A Question?
Are you looking for something but can not find it, or have a question for us? We would love to help you. Just fill out the form below and we will get back to you as soon as possible.
