How To Hook Up Cables In Your Rack.

ahoustondj

DJ Extraordinaire
Aug 13, 2007
3,465
Texas
So I have 2 Mackie self powered SRM 450 speakers. My XLR Out's on the back of my DJM 3000 mixer are going bunk. I don't always get a signal on my right side for some reason? I mess with the cables a bit, then it will come on. Grrrrrrr..... I think its a connection problem within the mixer itself from the XLR Outs on the back of my mixer.

So, I'm going to try to run my cables from my RCA Master Out's of my mixer instead of the XLR Outs, to see that fixes the problem.

I will have to buy some RCA to XLR male cables being that my Speakers have XLR males to connect into. Will there be a difference in sound if I buy some RCA to XLR male cables? I'm running each cable about 25 feet to each side.

Also is there a certain brand of cable that will do a good job with something like this? Does Gold connections help?

Let me know what you think, and thanks for your help!
Without reading the specs on your equipment, the outputs with the RCA connectors are not as powerful as those from the XLRs. The XLRs are also Balanced whereas the RCAs are not.
First swap the cables, if the problem remains on the same channel then it is not the cable..it will be either the connection from the Mixer or the Connection into the Mackie. If the problem transfers from one channel to the next, then it is the cable. Every DJ should have one. If you want to test your cables buy one of these http://www.amazon.com/Peavey-CT-10-CABLE-TESTER-Tester/dp/B004HR839M
 
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Back of my rack. The extra cables on the bottom are just about a foot extra of speaker cable. The XLR on top of the dsp is my mic/line mixer output for my mics to my board. I know I just posted the front else where but I put it here too for reference. Not my neatest work but was quick when I put this together. I will probably go back and clean it up now looking at it. Bothering me! :)View attachment 25990View attachment 25991
 

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steve149

Veni, Vidi, Lusi
Staff member
Sep 26, 2011
32,436
Prospect, CT
Maybe ... RCA is unbalanced. Balanced cables (XLR or 1/4" TRS) work by inverting half of the signal and then inverting it again on the other end. This way if noise is picked up, it will normally be picked up by both legs and then when 1 side is inverted again , the noise signal on that leg is inverted as well. Then the two legs are summed together with the regular and inverted noise cancelling itself out.

When you go unbalanced (phono or 1/4" TS) you don't have that effect, so any noise picked up will be amplified. If the cables are short (1-6 feet) you shouldn't have an issue. At longer lengths, you might get noise. Won't know until you try I guess, but it's not a preferred long term setup.
 

DJChas

New DJ
Aug 27, 2007
0
45
Maybe ... RCA is unbalanced. Balanced cables (XLR or 1/4" TRS) work by inverting half of the signal and then inverting it again on the other end. This way if noise is picked up, it will normally be picked up by both legs and then when 1 side is inverted again , the noise signal on that leg is inverted as well. Then the two legs are summed together with the regular and inverted noise cancelling itself out.

When you go unbalanced (phono or 1/4" TS) you don't have that effect, so any noise picked up will be amplified. If the cables are short (1-6 feet) you shouldn't have an issue. At longer lengths, you might get noise. Won't know until you try I guess, but it's not a preferred long term setup.
So I need to go from my RCA outs from the back of my mixer, to XLR Male in's, for my Mackie self powered SRM 450 speakers. Do you think this cable will work?? Also do you think the sound will be compromised? Thank you!
 

steve149

Veni, Vidi, Lusi
Staff member
Sep 26, 2011
32,436
Prospect, CT
It should work, but it will probably be noisy
 

DJ SVO

DJ Extraordinaire
Dec 21, 2006
2,882
47
Mexico City
DJChas,
What mixer are you using?
 

DJ SVO

DJ Extraordinaire
Dec 21, 2006
2,882
47
Mexico City
After reading your other post I would have the mixer checked out, you lose too much when going with the RCA's. It could be something simple or not but I would find out what the problem is.
 
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DJChas

New DJ
Aug 27, 2007
0
45
After reading your other post I would have the mixer checked out, you lose too much when going with the RCA's. It could be something simple or not but I would find out what the problem is.
I know I'm afraid of that....thx
 

steve149

Veni, Vidi, Lusi
Staff member
Sep 26, 2011
32,436
Prospect, CT
Another option, as you said one of the XLRs is ok, is to switch to mono on the mixer, and then daisy chain from one speaker to the other (same signal). The audience will probably not hear any difference and you can stay balanced on XLRs. I tend to run mono most of the time.
 
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DJChas

New DJ
Aug 27, 2007
0
45
Another option, as you said one of the XLRs is ok, is to switch to mono on the mixer, and then daisy chain from one speaker to the other (same signal). The audience will probably not hear any difference and you can stay balanced on XLRs. I tend to run mono most of the time.
Bingo!!! Thx Steve!! You have been a lot of help.
 
Wow this is a great thread. I've been pretty lucky for 10 years with the "knee" approach to cable management. Basically when the show is done if you are having a hard time shoving all the power/signal cables (I wrap em all together) into the back of the rack you simply place your knee against the back panel to get it locked. Good to go!
 

soundinmotiondj

DJ Extraordinaire
Jul 23, 2008
262
DFW, TX
Signal Loss Occurs in different ways. Signals cables loss before amplification can occur faster than loss on speaker cables after amplification. However there are factors that can change the equation one way or another, frequencies, type of conductors, level of processed signal (Pre amps), amplification of signal, gauge of wire etc. For regular DJ type systems Signal cables (Before amplification) of up to 30 feet is negligible. For Speaker cables, up to 100' is hardly noticeable.
I hate going back this far...but this thread popped to the top of the new posts list.

The above information is mostly wrong.

On the pre-amp side of the signal chain, there are low voltage signals. The cables can be "balanced (three conductor, or two conductor plus shield)" or "unbalanced (two conductor)". In general terms, xlr connectors (e.g. mic cables) are balanced. In general, 1/4" TS connectors, 1/8" stereo connectors, and RCA connectors are unbalanced. 1/4" TRS could be two unbalanced signals (e.g. stereo L & R) or one balanced signal...there is no good way to tell in the general case. See the Rane tech note for more.

http://www.rane.com/note110.html

Unbalanced signals are prone to picking up outside noise and outside electrical interference. The longer the cable, the more likely noise it to be introduced. In general terms, noise from the cable can be held to reasonable amounts in 10ft or shorter cables. I use unbalanced patch cables to connect music sources (e.g CD players, computer sound cards) to the mixer...and all these cables are as short as practical. Signal loss is not really a concern, when compared to the noise potential.

Balanced signals are much more resistant to noise and outside electrical interference. With balanced signal cables, it is possible to send a signal through hundreds of feet of cable with no significant signal loss or noise introduction. My personal best is 800ft. I was able to measure a 0.01v (the limit of my volt meter) loss across that distance. From the mixer to the amps, all my signal cables are balanced xlr.

After the amp, the signal is a high(er) voltage. This connection is two "unbalanced" two conductor. Here, resistance losses in the cable length become a concern, along with inductance in particularly long cables. In general terms, to keep the transmission losses to a reasonable level, the cable resistance should be <5% of the load. For an 8ohm speaker, that means the wire should have less than 0.4ohms of resistance. For a 2 ohm load (e.g. four 8 ohm speakers in parallel), the wire should have less than 0.1ohm of resistance. Using that rule of thumb, you can calculate the maximum length of a speaker cable based on the load and the wire gauge. There are many helpful websites with pre-done calculators.

In general terms, a 12 ga cable, at 50ft length (100ft of conductor, round trip) is the longest speaker cable that can be safely used with a 2 ohm speaker load. If you keep the load higher, or the cable shorter, so much the better. To be conservative, all my speaker cables are 12ga, and less than 25ft long. I place the amps near the speakers and run balanced signal cables from the mixer to the amps.
 

ahoustondj

DJ Extraordinaire
Aug 13, 2007
3,465
Texas
That is why it said "Different ways". My Quote was a direct extract from a Pro Sound Text. I did not make that up. What you quoted above is true but may not be a concern to most folks on here who hardly use anything longer than 15' in Cables. No sense in getting too technical for those people. Anyway, that was a spring off from the Original Topic of the Thread.
 

alfredclark

New DJ
Jul 2, 2013
3
The rack needs a proper cable management arm and fasteners that help manage excess cabling and secure your cables within the rack. The steps below describe how to use the cable management arm and fasteners provided with the rack.
 

Djtee

DJ
Oct 2, 2014
13
53
I had all the cables in my rack tied up neat and straight

until I had to replace one in the middle of a gig and couldn't trace it without ripping them all apart.

now I mark the ends of all of my wires with marker or tape
so I know where each one ends up
and I keep my IN's and OUT's straight, as well as my LEFTS and RIGHTS
I had all the cables in my rack tied up neat and straight

until I had to replace one in the middle of a gig and couldn't trace it without ripping them all apart.

now I mark the ends of all of my wires with marker or tape
so I know where each one ends uplabel
and I keep my IN's and OUT's straight, as well as my LEFTS and RIGHTS
Same here i label all my wires with marker and tage.
 

ahoustondj

DJ Extraordinaire
Aug 13, 2007
3,465
Texas
big rack organization
That is cool Brad! Where did you learn? I learned cabling, wiring, harnessing and soldering from NASA here in Houston. First couple Space Shuttle Missions.

I have pictures posted somewhere else on this forum.
 
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