How much hum?

[txstrat]

Since a large number of threads are hum related (my latest build too), I started to ask myself, how much hum would anybody consider as normal.
Sometimes when I play late at night and switch one of my tube amps on it seems to be too loud (hum-wise).
When I play the same amp in a normal daytime evironment I barely hear the hum (have to get quite close to the speaker).
I don't think I've encoutered a tube amp with literally NO hum, yet.
What do you say / think ???

[MWJB]

There are lots of amps with no hum, or if not "no hum" so little hum that it's barely perceptible...e.g. you only know that the amp is on because you can see the pilot light.

Any hum that detracts from your enjoyment of the amp, or prevents you from recording with it, or lining it out/micing it up on stage is too much hum.

Perhaps at night background noise is less, making your hum more pronounced, or it is exacerbated by lighting that you don't have on during the day?

[guitician]

No normal tube amp should have hum that is above barely noticeable. The tubes themselves are a prime suspect for hum sources. Also, if the amp only hums when the guitar is plugged in, the fault is not in the amp. I've noticed that when I fitted my LOUD amps with low gain tube types the hum level was drastically reduced. If your not into GAIN, then you could try lower gain types of the same pinout/specs.

[txstrat]

No normal tube amp should have hum that is above barely noticeable.

That's what I mean. WHAT is barely noticeable?
I can hear the hum of my tube amps when I put my ear close to the speaker. OK so far. When I'm 10ft away I don't hear ANY hum. See what I mean? What would you describe as normal hum?

[Alex R]

See, that's why I like the bias balance pot in silverface Fenders. Dial out the hum via the hum-cancelling properties of push-pull output stages. If the bias isn't in the ball park, change the resistor soldered to the pot. Some say change it back to a simple bias voltage control pot to 'blackface' the amp. Zealots!

[txstrat]

Yeah I've always liked the key note of the balance pot. Some go further and go for a two bias pot circuit (one for each tube). I believe partly to run the tubes exactly matched for sound reasons but also to cancel out hum.

But that's not what I intended with this thread in the first place. My amps are rather quiet (either more or less) and I'm satisfied with'em.
I think sometimes people are chasing rainbows in the attempt to make their amps even more quiet. I'd like to discuss, how MUCH hum anybody would consider as normal and how would you put that in words. Like: "No more than a fridge" or something like this. More or less for those of us, who don't know if their amps hum too much due to little experience. (I know it's still a question of nerves)

[dai h.]

it's probably subjective and depends on what you know and are used to. If you're used to a bit of hum, then having a bit is normal (it may even feel weird and abnormal not to have a bit--sort of anti-chaotic rock and roll/overly antisepctic). Conversely, if not then it's intrusive. Again I think it depends, so maybe for a jazz situation a minimal amount close to zero is "acceptable", while for rock it could be very different. On some older recordings you can hear lots of hum and buzz (Jimi or whomever), but evidently it didn't stop them from making music (but maybe they would have done something if they could have). Also, while the music is going it can be "drowned out".

[guitician]

Yeah, It all depends on the situation. If your playing amplified acoustic you would want less hum, to have a quiet background. In a hard rock band it will be washed out by all the loudness. I would say, that in a "normal" living room, a "normal gain" tube amp's hum shouldn't be noticeable above a whisper.

[GregS]

Hum level can depend a lot on the environment you're in as well if there are a lot of interference sources around. At the place I practice all amps are really noisy. Anywhere else they are fine.