Hot Cat Humming - Anybody Else Have This Problem?

[hardys]

I recently bought a used Hot Cat and find there is a noticable, low pitched hum through the speakers, that occurs even when all controls are turned to zero and no guitar cable is plugged in. My Dr. Z Stingray and MAZ 18 Jr. have almost no hum. I have swapped power and rectifier tubes, but that made no difference. The hum disappears when put on standby.

It's not loud enough to seem like a critcal problem where something is about to blow, but it's really annoying, especially for such an expensive amp. :bkw Do any of you Hot Cat owners have this problem?

[John Ward]

Does it sound like humming or more like a purring sound?

[WaltC]

My 1x12 Hot cat (new to me <G>) has a very low level (what I call) transformer hum when taken off of standby. I've seen such on lots of amps, even some of the ones I've built. Some amps will have it, others with exact same parts, circuit, and trannies from the same source, won't have it.

It's not objectionable, barely noticable and not a big deal, but it's there if you look for it.

It's hard to quantify the level, but on my amp it's definitely not audible if I plug in a single coil, the pickup hum covers it completely.

If yours is more pronounced than that then maybe a trip to a tech is in order.

[hardys]

My 1x12 Hot cat (new to me <G>) has a very low level (what I call) transformer hum when taken off of standby. I've seen such on lots of amps, even some of the ones I've built. Some amps will have it, others with exact same parts, circuit, and trannies from the same source, won't have it.

It's not objectionable, barely noticable and not a big deal, but it's there if you look for it.

It's hard to quantify the level, but on my amp it's definitely not audible if I plug in a single coil, the pickup hum covers it completely.

If yours is more pronounced than that then maybe a trip to a tech is in order.

Thanks for your input and yes, that describes the sound well. This morning, I put it on standby and then rested my ear on the amp. Although the hum stopped at the speakers, I heard the exact same hum (only much less so) from the chassis/transformer. Take it off standby and it's the same hum, only amplified through the speakers. It's not a huge deal, but I wanted to get some feedback from other Hot Cat owners and see if this is common with the amp.

[FFTT]

Mine get's a hum from time to time, but it goes away as soon as I touch
the input with a guitar jack.