transformer hum normal with tube amp?

[Rnm4]

Hi,

Got my new PPX3-6SN7. Loving the sound

, even while the tubes burn in. Glorious.

While signal path is abolutely dead quiet, the transformer hums just a little bit. Mikhail says that's normal, and I believe him. But how much is normal? I didn't notice it for the first 24hrs, and then did easily, so I got a bit concerned.

Please try to describe the amount of hum that would indicate something to be concerned with. I'm brand new to tubes, so clueless here.

Thanks

 

[Rob N]

Some mains transformers have some mechnical hum some don't,nothing to worry about.

 

[dwc]

I asked Mikhail the same question. Here's his response:

3. is it normal to hear audible (60hz?) hum when the amp is on? I'm not referring to through the headphones, but rather standing next to the amp. Should the amp be silent?

M: "All transformers, except for the Plitrons ($299), will have some audible sound. This is because the transformation of A/C current produces other energy forms as side effects - mechanical, sonic, and heat. Is the hum loud?"

 

[bg4533]

I have heard that DC on the AC line can cause some transformers to make mechanical noise. Try a different outlet in your house (something on a different fuse).

 

[adhoc]

transformers hum because the rapidly changing magnetic fields that accompany AC switching (the 'alternating') actually cause the soft-iron cores within the tranformers to distend slightly.

this distending inwards-outwards-inwards-outwards-inwards-outwards etc etc occurs at AC frequency, which is 60hz (110V, 60hz).

transformers in commonwealth countries hum at a different frequency - 50hz (corresponding with 230V, 50hz).

this type of transformer hum should NOT be confused with ground loop hum.

 

[recstar24]

yeah, transformer hum is just fine, it shouldn't be entering into the signal chain and you shouldn't be hearing it on the headphones or speakers, but its just a normal thing, that's all - now go and enjoy your ppx3, stop complaining

 

[Canman]

It is normal, but I understand how annoying it is. In my previous apartment, I got transformer hum in many of my components. In my new place, I don't seem to have that problem. For some reason, power from some locations may induce noise while others are silent.

 

[jamato8]

It is normal with some and not with others. If a transformers is correctly damped the audible hum can be very, very low, to the point that you would have to put your ear right up to the transformer. If a power transformers is correctly potted it is normally not a problem. DC can be on the main and this can cause problems. My preamp puts out 800 volts and the same transformer can handle to filaments (which many do but this can deal with a couple of amps) and the audible hum is about zero. If a transformer is mount on some type of thin damping material mechanical hum can be diminshed quite a bit for troublesome transformers (this is often done).

John

 

[adhoc]

Quote:

Originally Posted by jamato8 If a transformer is mount on some type of thin damping material mechanical hum can be diminshed quite a bit for troublesome transformers (this is often done).

iirc, ray samuels does this for his amps.