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Old 13th January 2013, 08:49 PM   #32621
fas42 is offline fas42  Australia
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Quote:
Originally Posted by qusp View Post
try listening to a track with -60db of attenuation.... or you mean with your ear to speaker? on headphones perhaps?

or pre-attenuated by -60db digitally and then amplified?
I used a Denon test CD, very handy piece of kit, a snippet of classical in successive tracks, mastered at 0, -20, -40, -60dB levels. With normal volume levels, the -60dB is completely inaudible at normal listening distance from speakers; so then move up to the speakers, put your ear to the driver, barely discernable sound. Start increasing the volume control, and here of course it varies per the gain of people's preamp, etc - but essentially you will need a volume setting which will blast you out of the room with a normal recording to clearly hear the -60db mastered sound ...

Frank
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Old 13th January 2013, 09:23 PM   #32622
gpapag is online now gpapag  Greece
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Originally Posted by simon7000 View Post
But for now I will change my PC layout practices and no longer route PC traces directly under components.
If the pcb traces you are referring to are for the return currents, these traces should be routed directly under the respective components (if it is not possible to be routed symmetrically around these components).
Routing them away from the components, will risk widening the magnetic loop, a call for interference.
I guess that jneutron has to comment on this.

George
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Old 13th January 2013, 09:36 PM   #32623
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Originally Posted by fas42 View Post
With normal volume levels, the -60dB is completely inaudible at normal listening distance from speakers;
I remember -60dB signal/noise ratio was the magic number in 1970.
Noise of a mastering tape was at this level with no Dolby, and peak modulation at +10. At the high level we were listening in studio, tape's hiss was very audible before and after music, or during pianissimos.
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Old 13th January 2013, 10:39 PM   #32624
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George

The point was the standard THD presentation is S + N. You got it!

Now the interesting issue is how we perceive signals. If you believe the ear responds to peak waveform and not RMS for timbre then noise is more important than is represented by the RMS value of the combination.

ES
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Old 13th January 2013, 11:37 PM   #32625
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Originally Posted by simon7000 View Post
Scott, I don't understand why you are confused. I thought you misreading everything was humor. The graphs in the data sheet are most likely straight from the AP and so are limited by those measurement methods. I don't understand why you keep defending the noise amplifier gain or input impedance. I assume you understand the difference between DC and AC performance.
Trying to follow you is always confusing. You said in that circuit you don't see the distortion being amplified as well as the noise. Did you read the original figure 4 it says divide the >AP< reading by 101? And I repeat the 10 Ohm and 1K Ohm resistors have no effect on the measurement. The circuit woks fine AC as well as DC for audio frequencies (certainly 1K). I quit on this, still waiting for the feedback going round and round.
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Last edited by scott wurcer; 13th January 2013 at 11:41 PM.
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Old 13th January 2013, 11:57 PM   #32626
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Originally Posted by scott wurcer View Post
... still waiting for the feedback going round and round.
Indeed: Like worrying for rms or peak value influence of pure silence !!! ( -110 or –134db)
"Now the interesting issue is how we perceive signals. "(LOL)
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Old 13th January 2013, 11:59 PM   #32627
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Originally Posted by scott wurcer View Post
Trying to follow you is always confusing. You said in that circuit you don't see the distortion being amplified as well as the noise.
Where? I really am being concerned about you. You either are confusing issues or posts. The issue was resistor noise in the first presentation in BP's column. You were the one that kept mentioning resistor distortion. I asked you about the circuit node values to be sure we were on the same page. Somehow you seemed to derive all sorts of nonsense from this

I thought I made it clear we were talking about the entire measurement system and you keep going back to two resistors. I deliberately tried not to provoke you when you ignored the importance of phase in the input impedence.

So Scott I really am concerned with how you are responding.

ES

Last edited by simon7000; 14th January 2013 at 12:10 AM.
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Old 14th January 2013, 03:06 AM   #32628
jcx is offline jcx  United States
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Default oh no, not an engineering trade off - can't I have it all?

Quote:
Originally Posted by gpapag View Post
If the pcb traces you are referring to are for the return currents, these traces should be routed directly under the respective components (if it is not possible to be routed symmetrically around these components).
Routing them away from the components, will risk widening the magnetic loop, a call for interference.
I guess that jneutron has to comment on this.

George
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Old 14th January 2013, 06:42 AM   #32629
gpapag is online now gpapag  Greece
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Quote:
Originally Posted by simon7000 View Post
Now the interesting issue is how we perceive signals. If you believe the ear responds to peak waveform and not RMS for timbre then noise is more important than is represented by the RMS value of the combination.

ES
Caution here Ed.
Transforming single isolated results into a hypothesis (“if you believe”) and bringing it into auditory perception area, may lead to erroneous conclusions.
http://www.diyaudio.com/forums/analo...ml#post3275314

But I’ll hit Scott’s nerves (feedback ) pointing to the long tested practice:
Noise masks low level signal details. At the same time there is a statistical -alas conditional - possibility for noise to mask low level distortion as well.
Lowering noise brings out low level signal details . Concurrently, the conditional masking of distortion by noise becomes even more conditional.

George
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Last edited by gpapag; 14th January 2013 at 06:48 AM.
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Old 14th January 2013, 06:46 AM   #32630
gpapag is online now gpapag  Greece
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Greed!

George
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