There's a mild form of tinnitus where the ringing is triggered only by certain frequencies and volumes. It comes and goes with these sounds. Since its not heard at other times it creates the impression of a spike or ringing coming from the system. A good test is to see if you hear it playing the same music at the same volume with earphones, ear canal phones or earbuds.
If that's what it is, not much you can do, you just learn to live with it.
If not then next is the room. Slap or flutter echo can create a frequency spike like that. Stand a few feet from a wall, clap, and listen. The sound should decay smoothly. If the walls are unbroken and parallel you may hear a rapid flutter or ringing sound as the clap bounces back and forth very rapidly. That's flutter echo. Try different places around the room. If you find a spot with flutter echo the simplest/cheapest/easiest treatment is buy one 2x3 ft sheet of 1" thick Owens Corning fiberglass panel. These are light enough to temporarily hold in place on a wall with stick pins or masking tape. You only need to treat one wall.
OC is very absorptive. You can easily over damp with it. Experiment to see how small a piece you can get away with.
The better but more involved solution is a diffusor panel. OC costs almost nothing. Its almost for certain you find some place to use it. Mine are in all the corners. Those little triangles are highly effective. https://systems.audiogon.com/systems/8367
If that's what it is, not much you can do, you just learn to live with it.
If not then next is the room. Slap or flutter echo can create a frequency spike like that. Stand a few feet from a wall, clap, and listen. The sound should decay smoothly. If the walls are unbroken and parallel you may hear a rapid flutter or ringing sound as the clap bounces back and forth very rapidly. That's flutter echo. Try different places around the room. If you find a spot with flutter echo the simplest/cheapest/easiest treatment is buy one 2x3 ft sheet of 1" thick Owens Corning fiberglass panel. These are light enough to temporarily hold in place on a wall with stick pins or masking tape. You only need to treat one wall.
OC is very absorptive. You can easily over damp with it. Experiment to see how small a piece you can get away with.
The better but more involved solution is a diffusor panel. OC costs almost nothing. Its almost for certain you find some place to use it. Mine are in all the corners. Those little triangles are highly effective. https://systems.audiogon.com/systems/8367