Loudspeakers Taking speaker out of equalizer

PDSaccman

Member
Hello,
We have an equalizer in our rack that has a pair of backstage speakers plugged in. I have consulted people on the outside and they say the eq is not actually "eqing" the speakers (The graph is flat). All it is doing is simply converting from 1/4" to XLR female. When I use an adapter cable to go from the amp to the snake and turn the amp on there is a hum coming from the speakers. There is no electrical cable near any of the audio cable. Any suggestions/solutions. We would really like ot use the eq for something else so is there another smaller device we can replace it with? Or will simply a cable work?

Thanks,
Joseph H.
 
Well - it sounds like the first thing to do is check your cable. I've certainly had several less than great cables that introduce annoying hums into systems. Can you check the cable some way? (1/4" DI out of a sound board into another channel on that same board then PFL and see if there's anything?)

Another thing to consider - is your cable stereo? or mono? if mono - what orientation?

I see no reason the correct cable should work - but there are a lot of cables that look like they should work at first glance that won't.
 
Well, what eq (brand/model) is it? I assume the backstage speakers are being used for monitors for bands, etc. If they are being used for anything that requires somewhat good sound, I'd be inclined to leave the eq there in the event it is actually needed and just pick up another eq for whatever else you need. I'm somewhat of a believer in having an eq on each monitor send - it can turn a horrible monitor mix into something useful.

If you don't want to do that, you will need something to balance the output, either by using a balanced out on the board, or a transformer of some sort (even the cheap $15 1/4 to xlr cans with a transformer would probably work fine).
 
Well, what eq (brand/model) is it? I assume the backstage speakers are being used for monitors for bands, etc. If they are being used for anything that requires somewhat good sound, I'd be inclined to leave the eq there in the event it is actually needed and just pick up another eq for whatever else you need. I'm somewhat of a believer in having an eq on each monitor send - it can turn a horrible monitor mix into something useful.

If you don't want to do that, you will need something to balance the output, either by using a balanced out on the board, or a transformer of some sort (even the cheap $15 1/4 to xlr cans with a transformer would probably work fine).

We have a dbx eq. I'm not sur won the model number. The monitors are pretty much used for crew calls so we can listen to music backstage nd as monitors. When we do a 3/4 thrust setup for some shows they become fully active speakers. We want to use the eq to eq some of our floor mics for an upcoming show. Will a di box work to balance the signal?
 
The Mackie aux outputs are what is called impedance balanced. Meaning the tip is connected to an active source, but the ring is connected to an impedance to ground that is equal to the source impedance on the other half of the line. In a true balanced output, both the tip and ring are connected to active sources. In theory, a impedance balanced output should be fine, but in practice there are times when some implementations of it don't seem to work well.

Few, if any budget conscious consoles have true balanced outputs on anything but the main busses. It's a cost cutting measure.

Is your equalizer located near the console, or close to the amplifier? I am also curious if you could verify whether the cable between the two locations is balanced (three-conductor) or unbalanced (two-conductor)?
 
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The Mackie aux outputs are what is called impedance balanced. Meaning the tip is connected to an active source, but the ring is connected to an impedance to ground that is equal to the source impedance on the other half of the line. In a true balanced output, both the tip and ring are connected to active sources. In theory, a impedance balanced output should be fine, but in practice there are times when some implementations of it don't seem to work well.

Few, if any budget conscious consoles have true balanced outputs on anything but the main busses. It's a cost cutting measure.

Is your equalizer located near the console, or close to the amplifier? I am also curious if you could verify whether the cable between the two locations is balanced (three-conductor) or unbalanced (two-conductor)?


The eq is in a rack with all the amps backstage. As for the cable the way it works know is there is an 1/4 inch cable coming out of the amp and into the output on the eq. I believe this cable is just TS not trs. Then the input on that is an xlr coming from a snake which goes to the board. In the booth, the other end of the snake gets converted to 1/4 inch and goes into the board.

I can double check on the cable tomorrow, but I am fairly certain it is TS (two-conductor).
 
Ah ha! Now we are getting closer to the exact problem. So, the input of the amplifier may be un-balanced, which was fairly common a few years ago, or the adapter cable you tried was un-balanced. The equalizer is acting as a balanced input for the amp, which eliminates noise on the long line. The problem is not the output of the console, it is the amp.

What kind of power amp is it? We can dig up the specs to see what the input stage is.
 
Ah ha! Now we are getting closer to the exact problem. So, the input of the amplifier may be un-balanced, which was fairly common a few years ago, or the adapter cable you tried was un-balanced. The equalizer is acting as a balanced input for the amp, which eliminates noise on the long line. The problem is not the output of the console, it is the amp.

What kind of power amp is it? We can dig up the specs to see what the input stage is.

Again, I can find out tomorrow when Im at school. I dont know if this helps, but the speaker wire on the amp end is just bare wire wrapped around banana plugs. It has a speakon connection in the back and we happen to have extra speakon lying around should we try replacing the cable?
 
i doubt the output from the amp is the issue, i have had connections like that and no hum problems from it.
 
so should we try to use a trs cable instead of a ts going from the amp to the eq? And again, I will try to get to the model amp that we have. It's weird all of our other speakers are on three mackie amps, but these monitors are on a completely different one.
 
if you have a shielded twisted pair TRS i would try goinjg from the board to the amp and see if you still get the hum.
 
You provided the model of the mixer and that is a big help, if you can provide the model information for the equalizer and amplifier that would also be of great help. With that information it may be possible to determine the best way to wire them and then you can compare that to what you have.

Also, many people think in terms of signal flow, so although the cable may be looked at as going from the equalizer to the amp of from the amp to the EQ, the latter may lead people to believe you are taking the amplifier output into the equalizer. To avoid potential misinterpretation it is often better to address cabling in a manner that reflects the signal flow, i.e. microphone to mixer, mixer to EQ, EQ to amp and so on.
 
You provided the model of the mixer and that is a big help, if you can provide the model information for the equalizer and amplifier that would also be of great help. With that information it may be possible to determine the best way to wire them and then you can compare that to what you have.

Also, many people think in terms of signal flow, so although the cable may be looked at as going from the equalizer to the amp of from the amp to the EQ, the latter may lead people to believe you are taking the amplifier output into the equalizer. To avoid potential misinterpretation it is often better to address cabling in a manner that reflects the signal flow, i.e. microphone to mixer, mixer to EQ, EQ to amp and so on.

Ok thanks.The amp model is a crown power line 1.
 

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