Acceptable level of hum at max volume?

If you have regulated filament supplies, even with a cathode/filament short in a tube there is no hum.

One thing have have found though is a lot of tube equipment manufacturers don't know how to ground their gear. I can name a few famous ones off the top of my head. *That* can certainly contribute to hum but also has nothing to do with tubes.

Actually, I may have overlooked one factor that does differentiate tubes from transistors, and that is with regard to the filament supply. I suppose it is possible, even in an indirectly heated triode, that noise in the filament supply could leak into the cathode, and the AC component might then be amplified as hum. In a well designed tube preamplifier or amplifier input stage, the filament voltage should be fully rectified to DC, with very low AC component, and regulated. If the filament supply circuit is malfunctioning or if there is a "leak" between filament and cathode within a given tube, the result might be a faint hum. In either case, repair is possible. (If the source is a filament to cathode voltage leak, the tube should be discarded and replaced. Perhaps that is what Jburidan experienced.) A competent tech should be able to figure that out.

Hum is not inherent in tubes even if there is no shielding, any more than in transistor circuits.

However, there are compromises that can occur in a design wherein a slight amount of hum at full volume might show up. I would contact the manufacturer and see if they think it might be normal.

Dear Roggae: Pbnaaudio posted:

++++++++++ A Phono Preamp has a LARGE amount of gain - some hum will almost always be present - if you cannot hear it at your listening position between tracks at normal to loud listening level - don't worry about it. ++++++

and Stringreen posted about some hiss level.

IMHO both are unaceptable by high-end standards. If we have it in our systems then we choosed the wrong electronics designs for the " job " or the wrong set up, period.

Regards and enjoy the music,
R.

Hey everybody! Thanks for your comments. I was just posing the question as I am also inclined to not worry about it. I was just tinkering and noticed it. It'd be interesting to hear with a SS phono preamp. Thanks again!

My system is dead quiet, but have had hum from a bad tube. I find any level of hum to be unacceptable.

Stringreen,
As I recall, your system is all solid state which is fine. Solid state circuits often are quieter. I've had both tubed and solid state and much prefer the tube sound even if it may not be dead quiet with an ear to the speaker. (who does that anyway?)
It's a matter of choice. LP's often have surface noise to some degree if you listen close enough. CDs are dead quiet. Most of us here still far prefer the LP. I agree with others here that anyone turning the volume to the max or going to other extreme measures to hear noise is focusing on the wrong thing. Play some music and just relax.

It seems to me that the less hum and noise in a system the better. All of that garbage stuff robbs amplifier power, and also reacts/modulates with the signal. In my system there is no hum and only the slightest hiss at absolute full rotation of the volume control. Lesser designed components will permit unwanted signal to enter the chain

Lewm> Hum coud be present in a tube circuit if tubes are not shielded. Leaving tubes unshielded helps get heat out and is a point of visual appeal for many people, whereas transistors are usually contained in a shielded box, because they aren't usually all that hot (they don't have a heater element like a tube for one thing), and I don't think they have a special visual appeal to a significant portion of the market. I'm not trying to be a wise guy here- I totally agree that if the hum isn't present at normal listening levels why feel the need to do something about it?

True hum, by the classical definition, is 60Hz OR 120Hz noise generated by unrectified AC voltage getting in to the signal path or by improper or inadequate grounding. The frequency would depend on the configuration of the rectifiers in your power supply. Since tubes and transistors are capable of amplifying those frequencies with equal efficiency, I see no reason why "hum" would be associated with tube equipment vs solid state. If this is what you are hearing, and if it bothers you, you could ask a technician to improve the rectification in your power supply or check the ground scheme, to reduce the hum. Any experienced tech or DIY guy would have some ideas of what to do. But as to what you are complaining about, I would do nothing.

Why are you listening at max volume? Is that the setting you usually use for for listening? If not, how about just checking hum at normal listening levels?

Roggae, you might check to see if you can lower the gain on the JD9 and still have enough signal strength feeding your integrated amp. I don't know which cartridge you're using or which outputs on the JD9 you have connected but if you use the high ("HI") output and the lowest gain setting ("MM") it should have the least amount of signal noise, which might reduce the hum you're hearing.

Regards,
Tom

It shouldn't hum at all....you may hear a hissssss with full gain, but not a hum

A Phono Preamp has a LARGE amount of gain - some hum will almost always be present - if you cannot hear it at your listening position between tracks at normal to loud listening level - don't worry about it.

As Always - Good Listening

Peter

Since your int. amp and phono stage are both tube based, IMHO, you're not hearing anything out of the ordinary.

My system has a tube preamp and a couple of different tube phono stages. It also has some hiss, (tube rush) if the volume is turned all the way up. Probably more than you are hearing. Never been a concern.