One of my amps has started making a soft crackling noise. The noise sounds like a combination of static and rustling leaves. The amp in question is a Weber 5F1 Champ clone that I built about 5 years ago. It is modified with a 5F2A tone stack replacing the low level input jack. Speaker is a Weber 8" alnico. Troubleshooting to date is as follows: 1. Replaced the 12AX7, 6V6GT, and 5Y3 tubes with new ones. No real change in the noise but the original 6V6GT apparently was on the way out as the new tube (JJ 6V6S) sounds louder and better. 2. Checked all mechanical and soldered grounds, all are good. 3. Touched up a few suspicious looking solder joints and replaced the wire to ground from the 12AX7 cathode resistor and bypass cap. 4. Tubes are not microphonic. Tapping on the solder joints between the input jack and the grid input of the 12AX7 with a wooden chop stick creates some noise but I think that is to be expected. 5. Cleaned volume and tone pot with Deoxit. 6. Noise seems to be in the 12AX7 stage as it goes away when the tube is pulled or volume turned down. 7. Tube sockets all cleaned. 8. Noise seems to increase as amp warms up. All this has resulted in a noticeable decrease in the noise but it is still present. It is not hiss. Any other suggestions or thoughts?