Frying sound from amp intermittantly

This unit will require an amp. I have set up several mixers and I
do not watch output level numbers, you can get desired volume using amp. It does no good to drive input levels high output levels high and the turn down amp. Lower your inputs so no light flashes set master gain to -6 output and then raise amp volume. I have set up 16 mic mixer set individual levels and the feed to main mixer and controlled levels with one fader. I have taken mixes from main mixer to another mixer to control audio on video feed. A good band does not let member's set their levels . the audio person set levels, bad bands have members to set own level with resultant a mess that gets louder and produces sub par event. Remember good bands sound good and bad bands only sound louder, and bad

You can put just about any instrument through any amp. The difference in sound will be whether or not that amp was designed for the particular frequencies of that instrument. Also whether or not the speakers you are using are designed for those frequencies. When playing bass you need speakers designed to carry low frequencies (40 - 400 hz); mid-ranges and tweeters don't cut it. Set your instrument volume on the guitar at 70 - 90 % to get the most signal from the instrument. Set output volume on the amp at 50 - 70 %, then adjust gain on the amp to get required sound level. You're not likely to blow the amp, but you could blow the speakers if the amp delivers more power than the speakers can handle. With a micro amp check the output rating. It's possible you may not have enough power to get the sound you want and as you turn up the gain the sound will distort.

Most likely cause for this is an intermittent potentiometer. Check to see if any of them are mechanically loose as this is a sign that they have been damaged and could have cracked the wiper surface inside the pot causing this problem. Alternatively, any switch that controls any gain setting could also be intermittent or dirty. Gain of the amplifier should be stable, but is controlled by the feedback and signal injection at the pots so that is where to look first. Good luck, as intermittent problems are tricky, but sometimes better than no function at all which can be more costly.

By ading in the harmony signals you are combining 3 signals so gain is probably going to be high you will have to reduce it before it goes to the amp or turn down the input gain of the amp.

NEVER use a pedal in the external effects loop of an amp as the levels are wrong.

check the "Gain" on the instrument you are plugging in ... if it is all the way down, that's the problem. If that's not it, check for a "Gain" control on the amp itself -- the is a volume control that takes care of the sound BEFORE it goes through the amp (pre-distortion etc.). Sometimes this is not with all of the other controls on the amp, so look carefully.
If it is not the gain on your instrument, and it is not the gain on the amp, then make sure you are not using too long of a wire to connect the two things. If you are using a 100ft cord to connect a guitar to an amp, there will be a lot of signal degradation in the wire, and it will be hard to get good volume from the amp since it is not getting enough signal to amplify.Try a shorter cord, and that might help ...
If all of these have failed, check the fuses on your amp. If there is a blown fuse anywhere, then your amp might not be getting the full power that it needs to produce the sound you are looking for (though a blown fuse usually cuts out ALL power through the amp, some models are built differently and this could cause your issue)
If none of these solutions work, try hooking the amp up to something else that you know works fine, to make sure it is the amp itself, not what you are hooking into it, that is not working right.
If all of this turns out to be an Epic Fail ... try speaking with customer service at the amp's manufacturer ... it might be a defect that they have seen before, and they may replace it, or at least give you a better solution that what I have done.

If this ties to a keyboard, make sure the keyboard and this are BOTH plugged into the same receptacle. You should send a higher level from the keyboard (turn volume up to around 70% or so) and use less volume at the input gain of this amp. Use more at master volume if the amp has one if needed. If the hiss is there with NO input cables plugged in and input gains at 50%, that is objectionable, the amp probably needs servicing. Unused channel gains should be clear down.

There are many models of Marshal amps icluding 15Watt types.

First thing to try is to see if headphones have normal volume. If they do, then the headphone jack switch that connects the speaker is LIKELY bad.

If the headphones do not have any volume, LIKELY causes are:

1. Fried output power amp

2. Volume pot is broken or has bad solder joints to the circuit board.

You MAY be exceeding the capability of the unit causing the thermal protect of the PA chip to shutdown. A 15 Watt amp is NOT going to make a lot of noise unless you have super-efficient speakers that are say 15 inch ones in decent cabinets. You still will be limited in sound level. Just because the gain control goes to a paticular number doesn't mean the amp can take it !!! Mpost of these use 7 terminal amp chips about the size of a TO220 transistor. Heat sinks are OFTEN very inadequate.

There are 2 channels, Which means there are 2 sets of knobs ... One for clean and one for crunch. Start out with a low master volume and set up the crunch, Then the clen and switch between the 2 and make adjustments until they match volume wise ... Then turn the master up.

Turn the volume down.
Check your gain.
That should solve it.