Loosing volumen and a high noise expecting when trying to play concern like a gorund problem or some thig like that the amp is 4 yrs old

I suspect you have a problem other than humidity.I suggest taking it to the repair shop.

"Overdrive Channel: high frequency noise as the gain and volume are increased."

This is the expected result, you are experiencing feedback. Try turning the "Contour" knob all the way to the left and turn down the tone knob on your guitar.

The 12ax7 preamp tubes will act just like that when they get old, in fact, this would be my 1st check before I go any further, other than ventilation and heat .Make sure you are using the right impedence output jack to match your cabinet. Make sure the effects mix level is not overriding your guitar signal. Also, make sure that your signal is not being clipped showing the red led's. Also, the variable limiter control, if turned up very high, will do that to a point similar to a compressor/limiter. I would definitely check the tubes for the crackling sound could be just that.

You have several options:

1. Do nothing and live with the occasional problem.

2. Check your guitar cable and the battery connections for loose or intermittent connections/noise. Try to see if it's the amp responsible for the noise....ie, Is it caused by vibrations, or maybe static....especially in winter when it's dry. Your home power may have noise on the line, so borrow or rent a power conditioner which filters out noise. If that fails, go to 3.

3. Bite the bullet and pay a competent guitar tech/luthier to repair it. Most of these issues are due to loose/faulty connections. Should be less than an hour. Hey....It's a Martin.

3a. Pay a guitar tech to loosen the end pin connector so you can see if you can repair it yourself.

You are probablly overdriving the unit. Too much gain saturates the electronics. The noisegate really only works to eliminate noise when input signal is below a certain level... it is NOT used or effective when at high signal levels. If you set gain too high the tiny signals will open the gate. The noise gate will prevent low signals like guitar "handling" noise from passing through until you are actually playing the guitar. This is the purpose of the noise gate.

This would be expected. Very high quality audio equipment like mixers for instance will have a soft mute during changes... you just don't find that on any of the guitar amps... The popping is lost in the rest of the "noise". I won't go into the technical explanation other than any slight charge difference at switch contacts or electronic switches will generate a pop when the circuit is closed.

Check for ground loops. Make sure the pedal power and amp are plugged into the same receptacle. Keep cables short, and if necessaary go to balanced lines to the amp. DO NOT have any lamp dimmers in the area of the audio cable to the amp. Use high quality instrument amp cables that have good shielding... DO NOT use speaker cables.

It could be the tubes themselves. I f you've had the for a while they can become microphonic. You're local tech should be able to test them for you. If it's not the tubes, then it could be a grounding problem. The electricity in most bars sucks as far as musicians are concerned.

Just a thought:

If you used the speakers with another amp and they still make noise when you play certain frequencies, then it is obviously a problem with the speakers or the cabinet - it could be a mechanical resonance in some part of a speaker / cabinet, something like a loose screw or a nut, loose protection mesh on the speakers that resonates at certain frequencies, possibly a bad speaker or a speaker membrane...

Also, you might want to check the pickups on your guitar, see if the pickup core slug under the A string is much closer to the string than the other slugs so it is either picking up too much signal and distorting it or the string might be touching the slug when you play it and cause noise, also see if the string is touching something else when it vibrates...

good luck

3rq8 (Triarcuate)

Could very well be the fan. The motors can cause interference. There may be a solution to get rid of the noise. Some copper shielding tape may help. You could rule out it being a microphonic preamp tube by turning the amp on as normal and tapping the tubes with something non-conductive. If you hear the tapping noise coming thru the speakers while doing this to a particular tube, replace it. With power tubes, the tops of them turn white on the top when they become microphonic, along with plenty background noise.