Originally Posted by penmarker
I have another question regarding electrical interference, But might be a stupid question, but I'll shoot anyway.
I have an Aune T1, a small tube headphone amp. I am planning to get the NAD PP2 phono preamp. Both of them has external power adapters.
Would it introduce any interference if I stack the tubeamp on top of the preamp to save space? Will the heat from the tubeamp affect the phono stage?
Oh dear - here we go, again , for the (n+1) times. But I will do it, as those n times were performed in the homes of audiophiles with humming/buzzing phono setups.
Phono gear has lower, in case of MC cartridges MUCH ( on average 20 dB or so, 10 times ) lower output levels and hence amplification gain for MM carts averages about 40 dB and for MC about 60 dB. If you allow for dumping any hum, radio frequency interference, cell phones in the vicinity of cart, table, cables leading to your phono input, phono stage - you ARE asking for trouble. This assumes an asymmetrical unbalanced connection of phono, that is to say RCA jack on the end of your cablew from the pick up arm. About 99 % of phono setups in the world - symmetrical balanced inputs are by definition almost unaffected, but if you are among those 1 %, you probably know why you did that extra mile already, so I won't be covering these.
It depends on your equipment and your requirements. I grew totally zero tolerance for hum - I always strive to get clean, evenly sounding "white/pink noise" from my phono setups - NO hum audible as identifiable as such. As this is head-fi, no need to emphasize this is best listened to with good sealing headphones and IEMs. It can not be achieved in each and every case, but once you do get it right for the first time and get accustomed to the sound, you will find just how much havoc is wrought by hum that is generally accepted as "inaudible enough".
Manufacturers of GOOD phono preamps went to great lenghts in order to get any noise, hum, RFI, etc, as low as it can get. Say that your phono preamp sits on top or on the shelf just above any other component - be it tuner, cassette deck, CD player, equalizer, power amp, whatever - listen to the hum/noise with headphones/IEMs with the bare minimum of equipment on necessary to get the signal from your table to the HP/IEMs - and that "minimum on" means not only that your other gear is switched off by their respective power switch buttons, but unplugged from the wall outlet ! Depending on your grounding arrangements, check that whatever minimum remained on, it IS grounded/earthed. You can try reversing the AC wall plug(s) in order to find a combination producing the minimum hum. Assume that now you have the absolute minimum pick up of hum, that this is your best possible result with this setup. Now start plugging in WITHOUT swithing them on all other components in the system, one at a time. It should come as no surprise to you that the ocean of silence you fought so fard to achieve is seriously compromised by the first thing you will plug into a wall.
If this happens, switch the offending component on - if you are lucky, hum will diminish, if not, it will get worse. Try reversing the AC wall plug. Repeat with other components in the system, one at a time, than in a concert - you should find which ones are detrimental/offending and which ones are not.
In general - you will have to establish some physical distance between phono stage and offending components. Of these, power transformer in the power amp will always be the biggest offender - that is why the hum on phono is nearly impossible to get rid of in integrated amplifiers/receivers - it is
in the same box with your phono and there is (pretty much, if you are good DIYer with electronics, might try some kind of additional shielding within the amp ) nothing you can do about it. Phono is the principal reason for separate preamps and power amps; in CD era with high level source/low preamp gain integrated amps WITHOUT phono stages are ever more numerous - no serious hum problems here.
With MC, and particularly VLOMC ( VERY low output moving coil, 0.15 mV/5cm/sec and less ), you will become expert hum extortionist - but expect some audiophoolePhille cables are utterly uncapable of achieving good results nomatterwhat. There is one cable I have tried and is heartily recommended for even the lowest output carts - XLO phono cable. Ebay is the ultimate measure of real quality of anything in the long run - and prices
If you are aesthetic about your audio gear positioning, if you run ultraexpensive cables tailor made to lenghts with an inch tolerance for moving your gear either place - the above described is your worst nightmare come true. But it is the only way to get your phono silent as it should be.
Forgot one thing - needless to say, if you must run signal and power cable in close proximity, ALWAYS try to cross them at 90 degrres and do not run them parallel or even bundle them parallel together.
Ultimate in phono silence achievable ? Benz TR cartridge ( 0.1 mV/5cm/s, output impedance 1 (one ) ohm ), either good transformer or head amp/MM imput combo or good MC stage - listening with Stax Lambda Pro /SRM1 MK2 to music > lifting the cartridge/arm from the groove > listening to the remaining residual noise > putting off the HPs and listening to the noise of a quiet lab will have the effect of someone pushing you abruply from the quiet of your home into busy city street.
For the ultimate in this hum extermination, best time of the day is quiet of the night, when "everything" else is sleeping, say around 2:00 AM. Funny thing - the improvement it brings is very audible at thundering levels of music too.
Edited by analogsurviver - 1/1/13 at 1:34am