Can there be silence when nothing is playing?

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Zen5656

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Joined 2012
#1
Hey!
I know this is a confusing question but I have to ask. I currently try to record my vinyl collection. Chain is:

Audio Technica 440mla cartridge
Technics SL1210 mk2 with/without standard cable (I have a few)
Lehman Black Cube Se phono Preamp + GND
Prism Audio Lyra 2 Audio Interface (the best)

When I do not have anything playing and the tonearm on the armrest I can hear a little bit of noise (not hum). It is not much but noticible. I can even hear it in vocal solos or so in the recordings when I listen with headphones. Somebody in a hifi shop told me I would always have noise in a analog chain which I want to to question here. Is it really normal to have a steady noise in the background if you invest over 1000€ for a analog turntable + phono preamp..? this is a bit shocking to me.. 😕

Thanks
 
#3
A bit depends on what sort of noise ur hearing.

Is it "hiss"?

How about with the input to the phono stage shorted (no TT connected)?

How about with the Audio Prism (whatever that is) only connected?
With the volume knob down vs. up?

You want to first isolate where in the signal chain the noise is being generated.

My opinion is that with normal 90dB/1w/1m speakers that the phono signal chain ought to be perceived as dead quiet, unless you've cranked the volume control wide open - which would be deafening and clip the amp dramatically if you were actually listening to music...
 
#5
There Will Always Be Noise. You can't eliminate it entirely, but you can manage it down to a level where it shouldn't be noticeable.

I would suggest reading up on Noise Figure with respect to amplifiers and using that information to structure your gains in such a way as to minimise noise. You might find with some measurement that maybe one of your components isn't as good as you thought it was, or that it is faulty and noisier than it should be.
 
#6
bear said:
A bit depends on what sort of noise ur hearing.

Is it "hiss"?

How about with the input to the phono stage shorted (no TT connected)?

How about with the Audio Prism (whatever that is) only connected?
With the volume knob down vs. up?

You want to first isolate where in the signal chain the noise is being generated.

My opinion is that with normal 90dB/1w/1m speakers that the phono signal chain ought to be perceived as dead quiet, unless you've cranked the volume control wide open - which would be deafening and clip the amp dramatically if you were actually listening to music...
Click to expand...

I did some testing with recordings and photos:
https://dl.dropboxusercontent.com/u/12325293/noisealex1.zip

I added a nanopatch volume knob before my recording interface (Lyra). This was also tested with direct connection to my studio monitors (Mackie HR824) so noise is nothing from the interface coming, The recording interface also has digital RIAA phono preamp filter and I already get noise from that. I should test a high quality tonearm (Rega) with the rest of the chain I think.. or do cartdriges have a noise floor?
 
#8
I read in the specs that the coil resistance is 3.2kohm. The calculated Johnson noise is 1 uV, which is 72 dB below the specified 4 mV output at 5 cm/s. This is the theoretical limit, and the RIAA preamplifier just adds to this. You are lucky if you get 66 dB margin at the end, and that is clearly audible.
 
#9
oshifis said:
I read in the specs that the coil resistance is 3.2kohm. The calculated Johnson noise is 1 uV, which is 72 dB below the specified 4 mV output at 5 cm/s. This is the theoretical limit, and the RIAA preamplifier just adds to this.
Click to expand...

It's worse than that. The cartridge also has inductance which increases the noise (less shunting effect of the 47k input resistor and interaction with the DCR current noise). The theoretical maximum S/N, referenced to the rated output (4mV) is -62.9mV, assuming 250pF input plus cable capacitance.
 
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