Question about Marshall Mg100dfx 100-Watt Combo Guitar Amplifier

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One speaker of my MG100DFX makes loud noise similar to a guitar disconnect. When that speaker is disconnected, noise stops. What is the suspected problem?

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  • Marshall Master
  • 5,603 Answers

NEVER disconnect a speaker with the power on the amplifier !!!!!! Good way to blow the amplifier.

If the speaker rattles while you are sending audio through it, it is likely damaged. It should be inspected as there are several failure modes, some of which as hazardous to your amplifier.

First test is to gently move the cone and listen for any rubbing of the voice coil. If you hear rubbing, then the speaker needs replacing OR re-coning.

Sometimes the magnet breaks off the back of the speaker.

Investigate this before further use.

Posted on May 15, 2010

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well theres only 3 sections of the amp the problem can be in. Pre-amp, Power amp, or speaker. First Unhook the speaker. If you can turn on the amp after that and hear your guitar through the headphone jack this means your pre-amp is ok. at that point you can just take a voltmeter across the 2 terminals of the speaker to see if oyu have 4, 8, or 16 ohms. that'll prove the speakr is good. I'd also try to connect and disconnect the pedal a few times to see if the normals in the jack on the amp are just being stupid. if all this concludes no success, you sir have a power problem.

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I have a Marshall MG100DFX. I turned my amp on a few days ago and I heard this loud sound (not the standard hum/buzz that you hear when you plug a guitar into an amp; it sounded more like a foghorn). Now,...


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No output


There are some possibilities. One, your speaker may be blown or disconnected. Make sure the wiring is still connected to the speaker and if you have one, try measuring the resistance(impedance) of the speaker with a volt ohm meter.Do this unplugged from current and disconnect one of the wires from the speaker or you will get a reading from the output stage. Two if there is a heaphone or line out jack it may have become faulty. If you have sound with the headphones plugged in your amp is still producing sound. Some jacks are designed to interrupt the signal to the speakers allowing you to practice without bothering anyone. If your amp has that feature and you still have sound with the headphones and your speaker tests OK then your problem is the jack. Hope this helps.

Jul 20, 2009 | Marshall Mg100dfx 100-Watt Combo Guitar...

1 Answer

Marshall MG100DFX noisy


Before you bring this into a shop, try spraying out all of the controls. Use an electronics switch cleaner that contains a lubricant. Spray into the control and work the control back and forth a number of times to loosen up any dirt inside. Then spray it again.

Let me know if that resolves the problem.

Thanks,
Dan

Feb 14, 2009 | Marshall Mg100dfx 100-Watt Combo Guitar...

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