My peavy kb300 produces a crackling noise & cuts off intermitently when I raise the volume on all 3 chanels.

If your Casio Celviano AP-65 turns on but there is no sound, there could be several possible causes for this issue. Here are a few steps you can try to troubleshoot the problem:

1. Check the volume: Make sure that the volume on the piano is turned up and that the volume control on any external speakers or amplifiers is also turned up.
2. Check the connections: Make sure that all cables and connections are securely plugged in and that there are no loose or damaged cables.
3. Check the power supply: If the piano is plugged into an outlet using an extension cord or surge protector, try plugging it directly into the wall to eliminate any issues with the power supply.
4. Check the internal speakers: If the piano has internal speakers, make sure that they are not damaged or malfunctioning.
5. Check the settings: Make sure that the piano is set to play through the internal speakers or any connected external speakers or amplifiers.

If these steps do not resolve the problem, it may be necessary to have the piano inspected by a professional. They will be able to diagnose the issue and recommend the appropriate repair.

This sounds like one of this nasty problems with the solder points. One of them might be faulty so sometimes there is a contact sometimes not. You could try to locate it by knocking gently with the plastic end of a screwdriver on the pcb. If vibrations cause the noise you could check all solder points optical or just resolder them. There are not too many. Also check all potentiometers! As they are mechanical parts vibration caused issues can be found here very often especially on their solder points.

1- check the outlet for power by plugging in a lamp or something
2- check the amps fuse. Most power amps have user replaceable glass fuses.

Does it make the noises at higher gains with nothing plugged in? If not, check your guitar cables and connectors.

Crackling is usally one or two things my guess would be bad grounding of the amp or bad connection with the jacks or plug it self try to make it crackle on purpose by jiggling the jacks see if it has any effect on the crackling try to narrow your possibilitys

I have a Korg C-15s and also experiencing loud crackling sounds when I turn it on. The problems seems to be either the sliding volume control or the amplifier itself. Honestly though, I believe the issue is the volume control. I opened my piano to get a closer look and attempted to clean the contacts on the volume. Unfortunately after cleaning the contacts, the crackling sounds became somewhat worse. After I turn the piano on, the volume control is generally rendered useless......volume set to low volume and the noise is quite loud and other times the volume control is set high and get very low volume crackling noise. No real consistency. The noise does diminish after a few minutes but so does the piano sounds to an inaudible level. There were a couple of instances where I turned it on and surprising enough, no no noise and perfect sound. For these reasons I believe the issue is within the volume control and not so much the amplifier. I have an electronics background and noticed that the volume control is very unique in design and is not something that can be substituted with another volume control from other sources.

My recommendation is to check the sound quality of the audio from the RCA L/R audio outs on rear of the piano by connecting to a stereo receiver. If it sounds fine you're in luck. If the crackling sound does not diminish after a few minutes like mine does, I would suggest disconnecting the internal speakers and using the audio out only. You can connect a pair of studio monitors or high quality computer speakers, preferably with a small subwoofer to deliver the full audio range and deeper tone of a real piano. I'm currently using a basic pair of Logitech computer speakers and is quite acceptable until I can afford a high quality set of monitors or relocate my piano closer to my high quality Yamaha receiver.

I hope this info helps a bit.

You have probably bypassed the crossover that directs different frequencies to the appropriate speaker/horn.

The speakers are designed to be used the way they were delivered. It is easy to damage them when connected wrong.

I would suggest you restore the circuit to the way it was designed to avoid damage to speakers or the amp.

okay so buzzing noise. i have seen this once before. the extension cord feeding a power strip with two amps plugged in and powered on off of a low amp electrical outlet with fluorescent lights overhead.......try running only one power unit off of the electrical outlet you are using, just one straight into the wall with the lights out. if you still hear it i wonder if the output transformer is starting to go south. if you listen close sometimes you can hear the buzz of a transformer powered on, example: you can hear the buzz of a power transformer on a power pole in peak hours. tubes usually make hisssing, crackling type noises. next would be to tap on the tubes while in play with an orange stick or pencil eraser to listen for microphics or the tapping itself thru the speakers. if you hear with out a doubt change them.

Hums are usually related to power, but not usually the actual power adapter. It's most commonly a "ground loop" issue, with the infamous 60Hz hum. The solution for this sometimes is to try plugging the keyboard (or amp) into a different power outlet, perhaps on a separate circuit.

Also try an audio cable of higher quality, which may have shielding or braiding in it to reduce external noise and cancel out internal noise. Also, shorter cables tend to produce less noise than longer ones

This could be many things. It is most likely noise from a defective chip in the unit. If sounds are normal except for the hiss, then test if the volume control reduces it. IF not, then problem is in the power amp section. If it does vary the loudness, then problem is likely between the D-A convertor and the volume control.

I would first try to isolate this by cooling selected parts with circuit cooler mist to see if you can find one that reduces the hiss when you cool it... Spray, then wait ten seconds before moving to the next on.

USUALLY semiconductors cause this, but rarely a bad resistor or cap can as well.