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GB for RTX6001 Audio Analyzer with AK5394A and AK4490
GB for RTX6001 Audio Analyzer with AK5394A and AK4490
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Old 15th January 2018, 11:41 AM   #791
soongsc is offline soongsc  Taiwan
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Quote:
Originally Posted by JensH View Post
Is that repeatable?

There are typically small fluctuations in the readout. And hum at this level is easily affected by placement and other influences due to the environment.



How did you scale the y-axis?

Attenuator settings?

FFT size?

Audio cable?
Not repeatable today. The 60Hz harmonic is there on both cables. FFT length is 131072. Smaller FFT length seems to raise the noise floor, is this expected? Rectangular window seems to lower the noise floor a bit.IMG_4971.JPG
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Old 15th January 2018, 12:49 PM   #792
JensH is offline JensH  Denmark
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GB for RTX6001 Audio Analyzer with AK5394A and AK4490
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Originally Posted by soongsc View Post
Smaller FFT length seems to raise the noise floor, is this expected?
Yes, this is expected.
Doubling the FFT length will reduce the noise floor by 3 dB. The total RMS noise is unaffected, but the noise is distributed over more bins, so every bin will contain a lower noise level.
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Old 15th January 2018, 01:11 PM   #793
PaulBC is offline PaulBC  Taiwan
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Some OPs are really hot, up to 70 degree Celsius.
I plan to install some heatsinks.
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File Type: jpg RTX6001_FLIR_thermal.jpg (179.1 KB, 151 views)
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Old 15th January 2018, 03:01 PM   #794
soongsc is offline soongsc  Taiwan
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The sound is amazingly clean and precise just using the unbalanced output. I wonder how it will work using fully balanced interface. The Tripp Lite cable seemed to give a lower noise level when running loop back harmonics tests in REW, so I decided to stick with this cable for now.
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Old 15th January 2018, 03:02 PM   #795
mbrennwa is online now mbrennwa  Switzerland
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Originally Posted by soongsc View Post
Not repeatable today. The 60Hz harmonic is there on both cables. FFT length is 131072. Smaller FFT length seems to raise the noise floor, is this expected?Attachment 656975
Yes, I'd expect everything to be like this.
The USB interface is galvanically isolated at the RTX, so it can't form a ground loop picking up hum.
Shorter FFT means wider frequency bins per FFT point, so each bin captures more noise.
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Old 16th January 2018, 07:12 AM   #796
DualTriode is offline DualTriode  United States
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DHL delivered a package to my door today.

Smaller bins same total noise, => less noise per bin. Greater number of averages and the smallest distortion spike looks huge.

Real world real time that tiny distortion spike is lost in a forest of noise.

The important noise figure we are not talking about is the 20K BW noise density. To some smaller degree small bin size and averaging will tend to fool us into thinking a apparently low noise floor is low noise, it is not.

Power line frequency / harmonics and IM products are what I do not like to see. Bin size and averaging do not help hide them. Real world real time they sound really bad.

DT
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Old 16th January 2018, 08:50 AM   #797
TNT is offline TNT  Sweden
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Originally Posted by DualTriode View Post
The important noise figure we are not talking about is the 20K BW noise density.
It would be really good if this became a "standard" like using 50dB scale on loudspeaker measurements..

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Old Yesterday, 08:33 AM   #798
lemon is offline lemon  Greece
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DualTriode, has received the RTX...very well!
JensH, the time is comming for us, or I am hurry!
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Old Yesterday, 05:29 PM   #799
JensH is offline JensH  Denmark
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GB for RTX6001 Audio Analyzer with AK5394A and AK4490
lemon,
I expect that the last order confirmations (payment requests) will be sent out this week.
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