new amplifier build

[khansen810]

My brother built this new amp per the following attached schematic which is a combination of various schematics. When he turns it on from cold it makes a crackling sound (white noise-no hum) for about 30-60 secs.. Once warmed up no crackling and operates fine. He noticed that if he removes the first 2 tubes and the mater control is fully cw it crackles a bit and the crackling increase when the master it turned ccw. It appears that this noise is coming from the phase inverter. All the tubes have been replaced by spare tubes he had and all the caps and resistors have been checked. Now the power transformer was a used one. At first it had a buzzing noise caused by loose lamination. He applied varnish which fixed it. Could the power transformer cause this crackling sound? Like I said the noise only occurs during warm up. We suspect that its being caused by the master vol. circuit (phase inverter). The master control is scratchy. Appreciate any comments regarding this issue. Thank you.

[shooter]

crackling is most likely a loose/bad/cold solder connection
should be able to find with chopsticking
can also be sloppy tube/socket fit, loose socket pins, dirty tube pins

[Bieworm]

I had the same problem once which turned out to be the rectifier tube  brand new. Also JJ power tubes gave me that issue once..