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?
That hiss is normal noise from a phono stage. Be thankful you don't also have a hum or buzz from a grounding issue to track down. For a low or medium output MC cartridge you can try the combination a step-up transformer with a phono stage in MM mode. The higher the step-up ratio, the more that hiss noise will be pushed down - however it is also increasingly difficult to retain sound quality with higher step-up ratios, and you have to be careful not to cut too far into the phono stage's overload margins, and also to not load the cartridge too heavily (which loses signal, and makes your signal-to-noise ratio poor again). Basically you'd typically want a SUT ratio of 10x to 30x for cartridges in the range of 0.5 mV to 0.3 mV. The other approach is just to buy a higher quality separate phono stage, and/or a cartridge with a higher output level. But some amount of hiss is normal - you'll have to judge what you consider acceptable or not. |
It is quite conceivable with the extra gain required to boost the much lower MC signal that the " hiss" is more noticeable to you now. Is it audible from your normal listening position? At a normal volume setting on the amp? Or do you need to crank the volume to hear it or be right up against the speakers. |
Definitely no hum or buzzing. Just a combination of “hiss” and a “rushing” noise. I can hear it at my listening position, at a volume setting I would consider to be medium. The sound comes out of both the tweeter and midrange drivers. The output of the cartridge is 0.3 millivolts - is that considered a low or medium output for a moving coil cartridge? |
0.3mv is right about average for a lomc and should not truly produce excessive hiss with a quality Phonostage. 60 to 65db of gain should be more than adequate, the higher the gain, sure it will require less volume control to play louder but the background hash or hiss will be conversely increased as well. I used to always go with the least gain possible for a decent listening level and no more. But of late I have also gone the SUT route and run into a MM only Phonostage right now. One table has some slight hiss ( yes Miller my Garrard 401!) But my DD tables are both inky black silent. I am not familiar with the p6, does it have adjustable gain or is it simply mm or mc options only? |
Definitely no hum or buzzing. Just a combination of “hiss” and a “rushing” noise. I can hear it at my listening position, at a volume setting I would consider to be medium. The sound comes out of both the tweeter and midrange drivers. The output of the cartridge is 0.3 millivolts - is that considered a low or medium output for a moving coil cartridge? Sounds perfectly normal to me. My Koetsu Black Goldline goes Origin Live Conqueror arm via hardwired OL phono lead into a Herron VTPH2A. There's better, but this will do. The Koetsu is 0.4mV, Herron 64 dB gain, Talon Khorus are about 94 dB or thereabouts. At a nice satisfying volume I can hear the exact same sound you describe- from the door 20 feet away. Easily. Read mulveling again, he nailed it. |
SUT-step up transformer http://www.kandkaudio.com/applications-guide/ I looked for the least techie article, but they all seem to be about the same. |
At normal volumes you should hear nothing. If you turn the volume up all the way you will hear some noise and it to try to play it at that volume you'll either blow an amp or break a loudspeaker. If you hear it at normal volumes then you have a noise source near your turntable. You have a lot of gain and can amplify almost anything. Don't take anything for granted. Unplug everything but the turntable, preamp and amplifier even the line conditioner and see what you have. Change the position of the turntable and see of the noise changes. If the noise disappears plug in one unit at a time and see which unit is causing the noise. Don't forget to make sure all your gain and load settings are correct for that cartridge. Good Luck, Mike |
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 |
After carefully reading and considering all the responses above, plus some additional listening, I have concluded the following: I believe the noise I am hearing, although much higher than I was expecting, is normal for my equipment. I do not believe it is a malfunction. It still bothers me, and I think I can even hear it on quiet passages of some of my classical music selections. I think the real issue is I am experiencing the limitations of the phono section of my P6 preamp. It is possibly made a bit worse by the gain required with a somewhat low output moving coil cartridge. My thinking at this point is I will need to upgrade to a separate phono preamp at some point in the future. Begin a fan of Parasound equipment, I am intrigued by the Parasound JC3+, which is about $3K, so I plan to save up for that, perhaps to acquire it some time next year. Thank you all for responding, and for "talking me off the ledge". After spending about $4K on a new cartridge/turntable combination, I guess I was just a bit surprised and disappointed. On a totally separate topic, I have the Telarc 1813 Overture on a UHQR version. I was rather surprised my $1800 Rega Apheta 2 cartridge can't track it successfully at 1.9 grams tracking force, and the turntable perfectly level and adjusted. Oh well, so little time, so many worries, and not enough money to spend... |
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 |
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 |