[ricmon]

What level of hum is considered acceptable?  At low to medium volume level it's not a problem.  However when I crank the volume to say a 1:00 to 2:00 o’clock the hum is very notable.  Is this just the nature of a phone section or can the hum be reduced past it current level?

[Merle]

The phono stage built into my NAD preamp is dead silent across the dial.

[ricmon]

I should have said that it's a AVA TR7.

[WEEZ]

It could be a cartridge issue, such as a loose ground somewhere. Maybe try the connections?

Or it could be a tube. Is the hum thru the speakers or external to the system?

WEEZ

[Zheeeem]

What level of hum is considered acceptable?  At low to medium volume level it's not a problem.  However when I crank the volume to say a 1:00 to 2:00 o’clock the hum is very notable.  Is this just the nature of a phone section or can the hum be reduced past it current level?

What kind of cartridge are you using.  Grados are unshielded, and you can get hum.

Otherwise, 1-2 o'clock seems to be a pretty high gain level.  I have a T-7 as well, with a FV350EXR and VMPS RM30s, and I rarely get above 10:00 and never above 12:00.

Be that as it may, I'm not keen on humm.  If it only comes through your phono, and if you are not using a Grado, then you're picking up something from somewhere else.  Could well be a ground loop hum from the TT or phono stage.  By way of experiment, you might try unplugging the TT and see if the hum still continues.

[Listens2tubes]

I had a Dynavector 10x5 with 2.5 mV output which was often in the 1-2 o'clock region. My Super Pas4i as well as the T8 was hum-free. Which cartridge/arm/table are you running?

[avahifi]

We consider 10 - 20 mV peak broadband noise from the phono section with the inputs shorted and volume control at max to be normal.  You may hear this with nothing playing at 2 oclock on the vol pot depending upon the efficiency of your speakers and gain of your amplifier.  Of course this would be break the windows level if the record was playing.

We do not use excess feedback as a noise reduction tool as is typical of mass market units inasmuch as this leads to distortion effects that destroy the musicality of the performance.

Note that the noise level of a tube preamp will mostly be dependent upon the quality and performance of the tubes in that unit.  Older tubes will get noiser and the base noise levels varies from brand to brand.  We are currently using JJ Electronic ECC83s tubes in our phono sections and find they provide consistant low noise performance and excellent musicality.

Frank Van Alstine

[avahifi]

The noise level mentioned above is measured at the line outputs, not the tape outputs, so it includes the residual noise of the line section too.

FVA

[ricmon]

Thanks for the info Mr. A and from your reply I it appears that the noise I'm hearing is in fact only an issue at elevated volumes.  Given that I'm not going to obsess over it.

[mikethep]

I have a TR7 that I am using with a high output MC cartridge (Dynavector 10x4) and there is
very little hum. It is not noticeable with a record actually playing. Surface noise is much
louder. I should point out that lately I am only listening with headphones. AKG701, which I
think have pretty decent bass response.