Mackie CR1604 - Balanced L/R line outputs? at DVinfo.net

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Old September 6th, 2004, 07:00 PM   #1
Fred Retread
 
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Mackie CR1604 - Balanced L/R line outputs?

My most frequent conmmunity theater venue has an old Mackie CR1604 (not VLZ or VLZ Pro).

For the next musical there I'd like to try taking left and right stereo channels (post fade, post mute, post EQ) from the board over XLR cable runs for my GL2 through a BeachTek DXA-6. But even armed with the CR1604 owner's manual I downloaded from Mackie's great web site I don't see how to get balanced lines to use for L and R channels (There is little expertise on hand when the facility is loaned to the theater group).

Two of the six Aux Sends would apparently be the likeliest candidates, but are unbalanced.

There are 1/4" TRS to XLR adaptor cords available in the booth

Any recommendations? Thanks.
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Old September 7th, 2004, 08:46 AM   #2
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There are only 3 balanced outputs on that board; the Main Left and Right, and the Main Mono. Which of these are they using for the house PA system?
You would need TRS 1/4" to XLR MALE adapter cable(s) to make use of these output(s). If the cables you mention have XLR female ends, then they are for input to the board. You could use male-to-male XLR gender changers with female cables. It all depends on what you can get your hands on easiest.
As you said, the aux outs are unbalanced. In addition, only four of the 7 aux sends can be active at one time. So you might not have as many available as you think.
The master buss insert jack is also unbalanced. You can insert an unbalanced cable in that jack TO THE FIRST CLICK ONLY. This will give you post-fader, post-mute master signals without interrupting the output of the board. However this signal is pre-MASTER fader, so you still might have to do some editing depending on how they run the board.
Those are your options unless there is something downstream from the Mackie that you can tap for a signal before it gets amplified.
How long will your cable runs be? With good quality cables you might be able to get away with an unbalanced run. The other alternative is to get two direct boxes to rebalance the aux sends or buss inserts very close to the board.
In addition, if you use two signals from the board then you won't be able to do an ambient mic if there's a problem (unless you use a second recorder). I know you haven't been satisfied with your ambient recordings in the past, but are you sure you want to rely totally on the board feed?
Let us know.
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Old September 7th, 2004, 07:10 PM   #3
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Thanks Jay.

Now that I have everything in front of me I recall clearly what the director gave me from the board last time. He said Oh, I can put everyting into the Monitor channel [Aux Send 1 with the Mon buttons pushed for each input channel] and plug a snake in there to give you an XLR plug to connect to. And that's what he did.

Sooo, I got a pre-fade, pre-EQ and I guess, pre-mute mix of all the input channels, coming out of an unbalanced output traveling down an XLR cable, terminated at the input to my DXA-8--which, contrary to B&H's web page, is not designed for line level inputs to begin with. Quite a setup. No wonder I was "disappointed" with the result.

There are two reasons for being willing to take a chance on a double board feed in lieu of any mics-- I normally tape several performances, and I plan on trying to borrow a second cam for a static wide shot anyway.

When you say I might get away with an unbalanced run, do you mean that XLR cable can be used with an unbalanced termination at the board and a balanced termination at my DXA-6? I can visualize that working if the 1/4" tip goes to pin 2 and the sheild goes to pins 1 and 3.

The length of the run from the board to my setup is about 30 feet, about 10 of which are vertical. My cables are Hosa 20 guage, $.50 per foot. Probably not what you mean by high quality cable.
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Old September 7th, 2004, 07:46 PM   #4
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You are correct on all points, although there are certainly worse cables than Hosa. If you are really worried about hum you could get two passive direct boxes like I said. Use a short 1/4" TS to 1/4" TS cable from an aux send into the direct box. Then XLR out of the direct box to your camera.
If you had originally taken the Aux 1 output, and with the switch in the Aux 1 position, you would have gotten a post-fader feed of all channels with the Aux 1 pot up. This would have still overpowered the DXA-8 inputs, but at least it would have been post-fader.
Your idea about the wiring from unbalanced to 3-pins is correct, but that makes the entire run unbalanced.
Let us know about which outputs from the board go to the PA. If they are using just the MONO out, then your problems are solved and you can use the Main Left and Right.
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Old September 7th, 2004, 09:55 PM   #5
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Aren't the Main left and right controlled by the master fader? If so, do you know what the range of the output level can be?

Anyway, the PA system is definitely fed in stereo, so the mains must be taken. For versatility, I think that adding passive direct boxes to my toolkit may be the way to go. Never heard of them before--thanks!

I'll keep you posted.
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Old September 8th, 2004, 07:54 AM   #6
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Yes they'd have to be using the left and right mains for stereo to the PA. They are controlled by the master faders. (The headphone level is actually the furthest fader to the right.) You can tap the main output signal before the master faders by using the Buss Insert jacks with an unbalanced cable to the first click only. That could still be an option. Just remember it's First Click Only, if you insert the cable all the way it will interrupt the output of the board. If at some point you decide to just get a single feed you could use the balanced mono out if they aren't sending that somewhere too.
The specs say the mains can output up to +28db with a balanced connection with the main faders all the way up. Normal zero level on the faders is the middle position.
If you're certain that you could always supply phantom power, you could also use an active direct box. These do have better sound qualities than some passive boxes but can be more expensive and do require phantom. Some can run on a 9v battery too. It's up to you what you want to spend, but they are handy to have. There's really a huge variety out there with prices all over the place. Scour the internet for sales.
Depending on how hot they have the Aux Sends set, and how a particular direct box handles the signal and how you set its switches, you will have to test whether mic or line input on your camera is most appropriate.
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Old September 8th, 2004, 06:35 PM   #7
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I'm looking at the Rolls AD82 at B&H. I can get two for $80. One maker of passive boxes claims that active boxes provide poor ground isolation. But the S/N 100 dB, Freq Response 1Hz - 50 kHz, 3-step attenuation and ground lift switch on the AD82 look pretty good to me.

I would also get a couple 3 foot phone cables, 1/4" male TS at both ends (does that length sound appropriate? I thought it would be wise to use minimal length), and, of course some gaffer tape.

I'd always be prepared to supply phantom power from the DXA-6

With the above and what I've learned from this message board and, maybe, the addition of an Oktava with the cardiod and hypercardiod capsules, I'll be pretty well set to adapt to what exists at my type of venues. At least much more so than when I showed up with the DXA-8, an AT897 shotgun, and the notion that I was owed good sound because I spent some money.
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Old September 9th, 2004, 06:04 PM   #8
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Sounds like a good plan. Best of luck with this round of shows. Write back and let us know how it goes or if you have any other questions.
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Old September 9th, 2004, 10:31 PM   #9
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Actually I do have another question. Do you know anything about the Electo-Voice BK 842 board? That's what they have at the high school where I teach. It's smaller (8 channel) with fewer outputs, but does have main bus inserts. I'm wondering if I can assume they have a first-click instertion postion like the ones on the Mackie. Electro-Voice's web site doesn't seem to offer any documentation on it.
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Old September 10th, 2004, 09:59 AM   #10
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I have no knowledge of that board. Most other brands do NOT have that "first click" feature on their insert jacks. Usually they are wired only to be a send AND receive using a TRS cable that splits into two unbalanced connections on the far end. These would be hooked through a processor like a compressor or EQ.
The post-fader Aux Sends or the Sub Outs, if the board has them, are usually the way to go if you can't use the main outs.
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Old September 13th, 2004, 06:55 PM   #11
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Jay, since direct boxes normally have two 1/4 " TS jacks in parallel couldn't I plug both TS ends of that splitter into the box, providing both a return to the board and an XLR out?
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Old September 13th, 2004, 06:57 PM   #12
 
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No, you cannot. If you do, you'll get a ground loop because the grounds are not isolated.
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Old September 13th, 2004, 07:02 PM   #13
Fred Retread
 
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Wow, Douglas that was the fastest response I ever got. Thanks.

Are you talking about the board's ground and the XLR's ground? If so, then what if it were a passive box?
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Old September 13th, 2004, 07:13 PM   #14
 
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A passive box might work on an insert point, but I'm not certain. Haven't ever tried that, but in theory it should work fine.
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Old September 13th, 2004, 07:58 PM   #15
Fred Retread
 
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Yet one more thing.

I'm a little unclear on getting left and right stereo mixes from AUX Sends.

From the front panel, each input channel will be centered or panned right or left to various degrees, creating the left and right main bus mixes that the sound guy wants, if I'm keeping my terminology straight.

Now, how would I get the same left and right mixes on a pair of Aux Send buses? If I crank up, say, Aux Send 1 to +4dB on all the channels that are panned left to any degree, and crank up Aux Send 2 on the channels that are panned right to any degree, and crank both up on neutral channels, That should give me stereo, but not the same as the main mixes, because if an input channel isn't panned *hard* right, then the left mix needs some of that channel too. So it seems that "artful" adjustments of each Aux Send level would have to be made by ear to approximate the main mixes. Is that how it's done?
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