I purchased a used Classic 100 Head about 6 months ago, but recently have noticed that the amp crackles when I play notes in the lower frequencies. This problem has gotten progressively worse over the last several weeks. Initially it seemed to go away when I turned the volume down a tad but now that doesn't suffice. The amp now crackles even with no signal going in.
This is my first prolonged experience with a tube amp, but my first thought is that the tubes are going bad. The preamp tubes don't seem microphonic, and I've checked that none of the cables/guitars were the issue through testing them on another amp. So that leaves the power tubes. Is there any other issue it could be?
Classic 100 Head crackle at low frequencies
Re: Classic 100 Head crackle at low frequencies
I had a similar problem with low frequency notes and it was indeed a microphonic valve. Have you tried the pencil test tapping the valves?
Re: Classic 100 Head crackle at low frequencies
Thank you for the reply. I did, but I'm not certain I really know what to look or hear for. The preamps all sounded the same, and the power tubes all similar to each other as well. I could try to record it later in the day if it would help though!Classic54 wrote:I had a similar problem with low frequency notes and it was indeed a microphonic valve. Have you tried the pencil test tapping the valves?