Unbalanced cables possibly causing speaker issues?

[interconnect]

Hi, I currently have two Mackie SA1521z loudspeakers and have been having a problem with one of them producing a loud buzz sound (not a ground loop or anything like that, I tested it thoroughly and the buzz was still present when no source was connected). I have had the same unit repaired several times in which the amplifier was replaced each time and that fixed the issue. I have never had a single problem with the other one I have.

However, it has happened several times and have been wondering why this is happening and if I am the one that is causing it to become damaged. When I bought the speakers, I also bought two 50' (and two 25') XLR-to-RCA cables from CablesToGo. The speakers accept a balanced input although the cables I bought are inherently unbalanced because of the RCA connection. These are the only cables I've used since I got them and is the only thing I can think of that may be causing the problem. Mind you, I've never pushed the speakers hard (never had the limit light come on) and take very good care of my equipment. Could the fact that I'm using an unbalanced cable on a speaker that takes a balanced connection be the problem here? The manual shows a pin diagram (on page 5) for the connection and says pin1=shield/ground, pin2=hot(+), and pin3=cold(-). The cable manufacturer does not specifically say how the cables are wired so there is no way for me to know how it is wired internally. Any advice would be greatly appreciated!

 

[markw]

If it was the cables the problem would have manifested itself right from the start.

Think about these for a minute:

1) You say one speaker has to be sent in for repair several times.

2) You say the other one never had any problems.

3) You say you're using the same cables on both speakers.

What does that suggest to you?

 

[interconnect]

Think about these for a minute:

1) You say one speaker has to be sent in for repair several times.

2) You say the other one never had any problems.

3) You say you're using the same cables on both speakers.

What does that suggest to you?

I've thought about those things before and I realize it doesn't make much sense, but I am dumbfounded as to why this is happening. I thought that it may be something I am doing and the only improper thing I have done is used those cables. I have had the amplifier replaced with a brand new one three times now and, at least according to Mackie, this is not normal at all. And each time it was replaced it was for the same thing; a loud buzz that was present even with no input signal and still present when plugged into different electrical circuits and at different physical locations.

 

[TLS Guy]

Hi, I currently have two Mackie SA1521z loudspeakers and have been having a problem with one of them producing a loud buzz sound (not a ground loop or anything like that, I tested it thoroughly and the buzz was still present when no source was connected). I have had the same unit repaired several times in which the amplifier was replaced each time and that fixed the issue. I have never had a single problem with the other one I have.

However, it has happened several times and have been wondering why this is happening and if I am the one that is causing it to become damaged. When I bought the speakers, I also bought two 50' (and two 25') XLR-to-RCA cables from CablesToGo. The speakers accept a balanced input although the cables I bought are inherently unbalanced because of the RCA connection. These are the only cables I've used since I got them and is the only thing I can think of that may be causing the problem. Mind you, I've never pushed the speakers hard (never had the limit light come on) and take very good care of my equipment. Could the fact that I'm using an unbalanced cable on a speaker that takes a balanced connection be the problem here? The manual shows a pin diagram (on page 5) for the connection and says pin1=shield/ground, pin2=hot(+), and pin3=cold(-). The cable manufacturer does not specifically say how the cables are wired so there is no way for me to know how it is wired internally. Any advice would be greatly appreciated!

I can absolutely guarantee the cables are not blowing up your amp.

You are getting incompetent service. I would be pretty sure that speaker has a defective power supply that is blowing up the amp boards.

 

[markw]

To put your mind at ease, switch the two cables in question. If it IS a bad cable, the OTHER speaker will blow. ...and you'll have isolated your problem to one particular cable.

Of course, if the same speaker still blows, well...

 

[interconnect]

I can absolutely guarantee the cables are not blowing up your amp.

You are getting incompetent service. I would be pretty sure that speaker has a defective power supply that is blowing up the amp boards.

I wouldn't think it'd be the cables either. I thought about the power supply as well, but since it is built into the amplifier, it couldn't be the issue as the entire amplifier/power supply/crossover/etc. is all one component and was replaced several times.

 

[TLS Guy]

I wouldn't think it'd be the cables either. I thought about the power supply as well, but since it is built into the amplifier, it couldn't be the issue as the entire amplifier/power supply/crossover/etc. is all one component and was replaced several times.

In that case it is just possible that what you are driving the speakers with has DC off set on that channel.

Check with an amplified meter to see if there is a DC voltage on the output of your driving device. This would be very unusual for a device other than a power amp, but it is possible.

What are you driving the speakers with?

If there is no DC off set then you are getting bad goods.