Question on phono input noise levels


Earlier this year, I had my Parasound P5 Preamp connected to my 35+ year old Bang and Olufsen turntable, with a moving magnet cartridge. I noticed that with the turntable connected (including the ground wire) I noticed quite a bit of hiss when not playing a record and the turntable was idle. In other words, the noise level was much higher when the input selector on the P5 was set to phono vs. other inputs.  Later, I upgraded to the Parasound P6 preamp. I noticed the same hiss, when the volume was turned up. I just assumed it was the turntable, since the problem (albeit minor) happened with both preamps.

As some of you may recall from a recent posting, I just purchased a new turntable. Yesterday, I received it - my new Rega P8 turntable with factory installed Alpheta2 moving coil cartridge. The hiss is worse!! So now I have experienced this background hiss with two different preamps and turntables. is this normal?  I'm wondering if the higher gain needed for the moving coil cartridge is adding to the noise level.  Could I be expecting too much out of the phono preamp section of the P6?

Note that both the turntable and amps have power run through an Audioquest Niagara 1200 line filter, so I do not think it is AC noise.  But the noise level is much higher on "phono" compared with other inputs.  Do any of you all notice this with your equipment?

btanchors

Showing 3 responses by almarg

P.S: For those who may not be familiar with the Telarc recording of Tchaikovsky's 1812 Overture, here is a photo of the groove on what I believe was the original release. Note especially the abrupt turn in the groove near the center of the photo!

I recall Harry Pearson in TAS commending Telarc for having the audacity to release a recording that was nearly unplayable.

Regards,
-- Al
I’m not specifically familiar with the UHQR version of the Telarc 1812 Overture, but as I recall the cannon blasts made Telarc’s original pressing unplayable on so many high end turntable/cartridge combinations that they released a second pressing and possibly even a third that were at least slightly less challenging.

And if I recall correctly from back in the 1980s some moving magnet cartridges, such as some of the Shure models, tended to have much better luck tracking it than most LOMCs, even the ultra expensive ones.

Good luck. Regards,
-- Al

The Parasound P5 and P6 have gains that are somewhat low for use with a cartridge such as your Apheta 2, which is rated at 0.35 mv. Both preamps have specified phono input "sensitivities" of 52 db, with the line stage of each preamp providing an additional 10 db of gain. And Stereophile measured the gain of the phono section of the P5 as being 53.9 db.

In addition, generally speaking I would not expect a full-function 2.1 channel preamp + DAC + headphone amp costing $1495 to provide particularly good noise performance in its built-in phono stage.

Also, FWIW, I use a Herron VTPH-2 (not 2A) in conjunction with an AT-ART9 LOMC cartridge rated at 0.5 mv, with the Herron’s stock tubes. If I turn the volume control in my system to a setting slightly higher than I would ever use (which is quite loud; some classical symphonic recordings I listen to can produce 105 db peaks at my 12 foot listening distance) the hiss produced by the phono stage is only audible within about 1 foot of the speakers. The Herron (which is only a phono stage, not a line stage or preamp) provides 64 db of gain and lists for $3650.

In addition to the SUT approach that was mentioned, a number of separate phono stages are available which cost considerably less than the Herron and have received a lot of favorable commentary here and elsewhere. The Gold Note PH-10 being one example. I believe that using a quality external phono stage connected to a line-level input of your P6 would considerably improve both the hiss and the sonics that you experience when playing records.

Good luck. Regards,
-- Al