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[Craig Cernek]

Are the horns in 2 of my 4 floor monitors blown?

I have set up a monitor system for our band. Vocal and amplifier microphones plus line level instruments directly connected to the 8 channel inputs of a Korg D888 mixer.  The stereo monitor outputs of that mixer go through 2 balanced Prolink Monster Cable interconnect cables into the inputs of a Yamaha P3500S power amplifier. Both channels of the amplifier are set to not use any filter, not use YS processing, and are set to work in stereo.  Each of the two amplifier channels are connected to two Yamaha SM10V floor monitors in series, for a total of 4 floor monitors. All amplifier and monitor inter-connections use Live Wire Elite speaker cables with Neutrik Speakon connectors.

The manual for the amplifier claims that it has some type of a protection circuit to protect the speakers. The manual for the monitors claim that they have a self-resetting poly switch meant to protect the high-frequency driver from damage caused by excessive power.

I've been using this setup for a couple of months now, and last week I noticed that in one of the two monitors on amp channel A, the horn produces no sound. On the other monitor on channel A the horn produces a much quieter sound than the 2 monitors on amp channel B. The 2 monitors on amp channel B sound great.

How can I determine if the 2 horns connected to amp channel A are blown. Could there be something else wrong?

[Greg Cameron]

How can I determine if the 2 horns connected to amp channel A are blown. Could there be something else wrong?

Run a tone sweep through the monitors one at time. if you don't hear anything in the high frequency range above the crossover point (1.8kHz) from the horn, either the horn is blown or something on the crossover is blown. Remove the horn from the box and measure the resistance across the terminals. If you get nothing, it's probably a blown diaphragm. Buy new ones, they're cheap. Then figure what you did to cook them.

[Ivan Beaver]

I would swap the ch A monitors with the Ch B monitors and see if the problem follows the monitors or stays with the channel.

THEN I would start to take them apart.

If it is in the monitors themselves-it could be any number of things-bad diaphragms-cracked connection in the crossover-defective crossover parts etc.

You have to approach this one step at a time-like any troubleshooting problem.

[Craig Cernek]

Run a tone sweep through the monitors one at time. if you don't hear anything in the high frequency range above the crossover point (1.8kHz) from the horn, either the horn is blown or something on the crossover is blown. Remove the horn from the box and measure the resistance across the terminals. If you get nothing, it's probably a blown diaphragm. Buy new ones, they're cheap. Then figure what you did to cook them.

Thanks for the reply.

Clarification: The horn in one of the 2 monitors connected to channel A  makes no sound, while the horn in the other one is very quiet.  The horns in the other 2 monitors connected to channel B are loud and clear.

While I don't know how to perform a tone sweep through the monitors, I did pull the horn and measured 7 ohms across its terminals.

[Craig Cernek]

I would swap the ch A monitors with the Ch B monitors and see if the problem follows the monitors or stays with the channel.

THEN I would start to take them apart.

If it is in the monitors themselves-it could be any number of things-bad diaphragms-cracked connection in the crossover-defective crossover parts etc.

You have to approach this one step at a time-like any troubleshooting problem.

Thanks for the reply.

Clarification: The horn in one of the 2 monitors connected to channel A  makes no sound, while the horn in the other one is very quiet.  The horns in the other 2 monitors connected to channel B are loud and clear.

I did swap the monitors for him from and output A to B and the problem follows the monitors.

[Craig Cernek]

THEN I would start to take them apart.

If it is in the monitors themselves-it could be any number of things-bad diaphragms-cracked connection in the crossover-defective crossover parts etc.

You have to approach this one step at a time-like any troubleshooting problem.

As I said in my last post, I pulled the horn from the monitor in amp channel A that produced no sound, and swapped it with the horn in amp channel B that sounded perfect.  The problem stayed with the monitor in amp channel A.  The horn in amp channel B now sounds perfect.

So, I would say it's a problem with the crossover.  I fiddled with its wires, and each component, and all seems firmly intact. Visually none of the components appeared to be burned, or melted. Is it possible for me to blow a crossover?

[Ivan Beaver]

As I said in my last post, I pulled the horn from the monitor in amp channel A that produced no sound, and swapped it with the horn in amp channel B that sounded perfect.  The problem stayed with the monitor in amp channel A.  The horn in amp channel B now sounds perfect.

So, I would say it's a problem with the crossover.  I fiddled with its wires, and each component, and all seems firmly intact. Visually none of the components appeared to be burned, or melted. Is it possible for me to blow a crossover?

Yes it is easy to damage some crossovers.  Since we don't know what kind of monitors you have-we have no idea how easy it may or may not be to damage the crossovers.

And of course there could always be a' "Break" somewhere.

Very often poly capacitors don't show anything when they are bad.  Paper ones will usually "explode" and be VERY evident.

And wirewound  resistors will sometimes open up without showing any evidence.

If you would post some photos of the crossover-that might help.

When you measured 7 ohms across the diaphragm-did you disconnect one of the wires to it?  If not-then you could be reading the "backside" of the crossover.

You are going to have to provide more information to get more help.

So model numbers and photos of the crossover would be a good start.

[Craig Cernek]

Yes it is easy to damage some crossovers.  Since we don't know what kind of monitors you have-we have no idea how easy it may or may not be to damage the crossovers.

And of course there could always be a' "Break" somewhere.

Very often poly capacitors don't show anything when they are bad.  Paper ones will usually "explode" and be VERY evident.

And wirewound  resistors will sometimes open up without showing any evidence.

If you would post some photos of the crossover-that might help.

See attached.

When you measured 7 ohms across the diaphragm-did you disconnect one of the wires to it?  If not-then you could be reading the "backside" of the crossover.

Both wires were disconnected when tested.

You are going to have to provide more information to get more help.

So model numbers and photos of the crossover would be a good start.

They are Yamaha SM10V floor monitors. Crossover photo attached.

[Bob Leonard]

With a low level sound going to the cabinet and all drivers connected jumper the capacitors one at a time with a piece of wire. Replace the bad capacitor you find.

[Craig Cernek]

With a low level sound going to the cabinet and all drivers connected jumper the capacitors one at a time with a piece of wire. Replace the bad capacitor you find.

Thanks. I've attached the photo updated to identify each component. Are there in fact four capacitors as shown?

Presumably, your test to find the bad capacitor will change the sound. Am I correct that jumping a bad capacitor will make the silent horn sound? What will jumping a bad capacitor in the quiet horn sound like?