(Page 4 of 4 pages for this article « First  <  2 3 4)

Monday, February 17, 1997

I Can’t Hear You: Correct Audio Connections

After we get our computers stable and video cables connected, it seems to be the audio wiring that befuddles us the most.

Rewind & Rewire

Head swimming? Let’s put all this to practical use. For example, if we were going to wire the equipment mentioned in the story on the first page using correct cables, this is how we would proceed:

• Out of the BetaSP deck, connect the pro-level balanced XLR audio connectors to a format converter such as a Henry Matchbox. The output of that will now be line-level unbalanced RCA connectors. If a Matchbox isn’t available, in a pinch we could take the monophonic line-level unbalanced RCA “monitor” output, and split it into faux stereo with a single RCA to dual RCA adapter. (We later gave that facility our Matchbox when we got our Ebtech Line Level Shifter.)
• Run a pair of RCA cables to carry our stereo unbalanced line-level signals to the matching inputs on the back of the VHS deck.
• To the line-level unbalanced RCA audio outputs on the back of the VHS deck, connect a pair of single RCA to dual RCA splitters. Why? Because we eventually want the signal to go to two places: the computer monitors on the table in front of us, and the audio amplifier that will feed the rest of the room. Therefore, we need two copies of each channel (left and right).
• Run a pair of RCA cables from one set of our left/right splitters above to the computer speakers on the desk. If the speakers have a Walkman-style jack input instead of RCA jacks, connect these cables to a dual RCA to 1/8” stereo adapter. (This is also what you would do to take audio from the video takes and run it into the computer.)
• Run a second pair of RCA cables from the other set of our left/right RCA splitters to carry our line-level unbalanced signals to the audio amplifier, which in turn powers the main speakers in the room.

This arrangement will work and sound better. However, there is another way: Use an audio device known as a “mixer.” Our dream set-up would take the audio outputs from our BetaSP and VHS decks, as well as perhaps the computer itself and a microphone, bring them all to one place with a volume control on each signal, and then send them back out to our main amplifier as well as some other destination such as computer speakers or one of the video decks. I highly recommend adding such a device to your studio as soon as you get past the “one video deck and one computer” stage.

There are several mixers than can perform this job; I happen to use a Mackie 1202 (street price: roughly $300; view on Amazon here). It features four inputs that have both 1/4” and XLR connectors, and can be set to accept any signal level from the professional +4dB down to a microphone’s -50dB and make it match the rest of your world. You could use two of these channels to handle the BetaSP’s output, and have two spares for microphones. It also has four additional stereo pairs of 1/4” connectors that are great for handling unbalanced line-level signals - connect the VHS deck, computer, and perhaps even a cassette deck or CD player into those (with the appropriate adapter connectors). It has two pairs of outputs - one on RCA connectors, and one on 1/4” - that can be run back to your amplifiers or other sources. It also has a headphone jack on the front for private listening. It is built like a tank, and is the unit I bring with me when I have to travel to trade shows to speak.

If the Mackie 1202 is too rich for your blood, Behringer makes quite a few inexpensive mixers that are not as sturdy as the Mackie but still quite functional; I’ve used a few of their Eurorack 1204s in different situations, while their MX602A is perfect for many small setups. I leave these safely at home or bolted into racks rather than subject them to the rigors of the road.

Audio •

(Page 4 of 4 pages for this article « First  <  2 3 4)

Q&A: Audio Queries

Chris Meyer | 04/17- 09:56 PM

Two New Location Audio Recorders

Jim Feeley | 04/17- 05:03 PM

RED Build 15 EI Tests

Art Adams | 04/11- 07:54 AM

AKG Revamps Headphone Line

Scott Gentry | 03/05- 01:28 PM

Adobe Soundbooth sale; new audio blog

Chris Meyer | 03/05- 09:24 AM

As noted at the end, the Mackie is my “I’m heading into the wilds and I need to be absolutely sure it works, and works well” mixer. If I’m going to be in a more controlled environment (i.e. nobody’s going to drop it), I have time to make sure I understand the signal levels, and I’m trying to save some bucks, then the Behringers will do. I had a Behringer in the tape deck rack in our studio for years, but I’m bringing the Mackie to NAB for my audio session…

- Chris

Posted by Chris Meyer  on  03/18  at  09:57 PM

---

By the way - if you are connecting your MacPro to a mixer and/or other gear, I would get a Radio Shack Ground Loop Isolater for the connection. (See http://provideocoalition.com/index.php/cmg_blogs/story/buzz/)

good luck -
Chris

Posted by Chris Meyer  on  03/18  at  10:01 PM

---

May I also recommend at least two of Sure’s in-line XLR variable attenuators. I know of no simpler way to handle the myriad of different line levels, and line to mic levels than these buggers. They’re cheap, small, durable, and- variable.

Lastly, as ubiquitous as iPods are, an adaptor that goes from 1/8” stereo to RCA + RCA to 1/4” adaptors and RCA to XLR adaptors allows me to put my audio into any source deck and make sure the path after the deck is working- without playing my actual program material.

This is a great way to slowly ease up the audio on the iPod and not be startled by some super loud volume the previous user left because their program audio was so low.

Posted by Anthony  on  03/20  at  02:49 PM

---

Good suggestions, Anthony. And as long as you are filling your survival kit, Shure also makes a transformer with an XLR on one end (for a mic) and a 1/4” tip-sleeve phone plug on the other for plugging mics into line level inputs.

BTW, those 1/8” stereo to dual RCA adaptors are the quickest to die; keep extras around.

- Chris

Posted by Chris Meyer  on  03/24  at  10:12 PM

---

Name:

Email:

Location:

URL:

Smileys

Remember my personal information

Notify me of follow-up comments?

Submit the word you see below: