Troubleshooting
Crackling Noises
This is probably due to a cold solder joint. Check all solder joints. If there are any in question, remelt them with a soldering iron. Check your cables also. Sometimes cables start to wear down (especially at sharp bends) and make crackling noises.
Squealing Noises
This can be many different things. A common issue is tube failure. If you have extra tubes, try replacing each one in your amplifier and testing the sound each time. If you don't have extra tubes, try rearranging your preamp tubes to see if there is a difference in sound. If there is a difference in sound, then you need to replace a tube.
This can also be due to grounding issues (see below).
Hum
A common source of hum is grounding issues. Make sure that all ground wires are connecting and that they are not cold solder joints. Make sure that the star ground is connected to the chassis well.
Another source of hum is not amp-related. A lot of times, hum is caused by poorly shielded guitars and cables. Most guitars are not shielded well. Please search for this in google, since there are websites out there dedicated to shielding your guitar
Check Wiring
If none of this has fixed your problem then make sure that you have wired correctly. I once built an amp which turned on but made zero sound. I checked all my wires, twice over and found nothing wrong. I then checked the turret board (which came to me pre-assembled) and there was a missing connection! I soldered that together and the amp performed well from then on.
Help me, I'm still stuck!!
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