At what level is noise heard in your system?

[RayDunzl]

Normal (even loud) listening creates a current draw nowhere near the limit of the mains circuit.

And yes, average is 15 to 20dB below peak.

TV is running right now: peak 17.2dB above average

 

[Wombat]

If you can hear system noise from your listening position at idle then you need to attend to system connections, house wiring or, heaven forbid, your choice of componentry.

If you can hear it at listening levels you need another interest.

(or learn real stuff vs internet chatter).

 

[RayDunzl]

Added 3pm ambient noise floor in the post above, to contrast with 2am noise.

https://www.audiosciencereview.com/...-heard-in-your-system.1013/page-3#post-128981

 

[Soniclife]

My noise floor is in this post.
https://www.audiosciencereview.com/...140-the-limit-in-measurements.2700/post-76409

I redid this test the other night after listening loud for an hour, I could not hear the 70db.

 

[etc6849]

This eBay win just came in the mail... I feel like doing a 2AM noise floor check now too.

Added 3pm ambient noise floor in the post above, to contrast with 2am noise.

https://www.audiosciencereview.com/...-heard-in-your-system.1013/page-3#post-128981

 

[Wombat]

This eBay win just came in the mail... I feel like doing a 2AM noise floor check now too.

View attachment 19196

Did it come with a current Calibration Certificate?

 

[etc6849]

No cal certificate, but I paid about 1/5 of new price so I'm happy. I tested it with a cheap SPL meter I have and it appears to be accurate. Should be really nice for calibrating level in REW since my mic came with a cal adapter.

Did it come with a current Calibration Certificate?

 

[etc6849]

@RayDunzl

Thanks Ray! I learned from and liked the settings you used, so I copied them I'm using a Benchmark ADC1, Benchmark MPA1, and a Earthworks M30 (all bought from eBay).

A complete file with these saved measurements: amps off lights off, amps off with lights on, amps on, and the calibration source set to 114dB is found below:
https://drive.google.com/open?id=1sB-dLejnQvsE9mvUBLGA0_A5mZRzm143

Amps off, lights off (I'm outside the room too):

Calibration source I got from eBay set to 114dB:

 

[RayDunzl]

Calibration source I got from eBay set to 114dB:

I didn't expect to see such a high level of harmonic distortion, but, I have no experience with a calibrator, nor a mic at those levels.

Comparing the UMIK-1 and REW readings with two other meters made me think "close enough".

114+70+83+50 = 114.3dB, so I guess it doesn't matter.

 

[etc6849]

Thanks! It seems super handy for what I paid, but I'm glad I didn't pay $220+tax for it.

As you point out, it is so close it doesn't matter. It seems it is likely within the specified accuracy of +/-.5dB. I would think the 94dB reading would be cleaner, but I already put everything up or I'd check, doh!

http://www.amprobe.com/amprobe/usen/environmental-testers/sound/amp-sm-cal1.htm?pid=73340

Electrical (sound) standard: ANSI S1.40-1984 and IEC942 1988 Class2.
Output sound level: 94dB and 114dB re 20 uPa under reference.
Accuracy: ± 0.5 dB.
Output frequency: 1 kHz ± 4 %

114+70+83+50 = 114.3dB, so I guess it doesn't matter.

 

[trl]

[...]

Amps off, lights off (I'm outside the room too):
View attachment 19197

I wonder if the +40dB @20Hz is really there or it's measurement issue. However, it's really quiet in there.

 

[RayDunzl]

I wonder if the +40dB @20Hz is really there or it's measurement issue.

I can't say if the reported LF levels are correct, but the reported SPL increases and decreases with human activity, as I interpret the 2am and 3pm readings above.

 

[etc6849]

I would think it has to be the room as the mic I am using has a ~22dB self noise (latest Earthworks M30 has an even lower self noise).

I don't think it is the equipment, but... This weekend I will test an analog loop-back via a Benchmark ADC1 and Benchmark DAC3 DX to be sure.

I wonder if the +40dB @20Hz is really there or it's measurement issue. However, it's really quiet in there.

 

[Blumlein 88]

Trains can really muck up low frequency levels from miles away.

 

[RayDunzl]

... and helicopters.

 

[etc6849]

For fun, to check my volume control (RME TotalMix using the Hammerfall DSP ASIO driver), I was able to get a digital AES loop-back by connecting the AES inputs and outputs for CH 8 of my RME card. I then used REW's generator to output a 1kHZ sine at 0dBFS.

I changed the volume in TotalMix as shown below (-62dBFS, -50dBFS and -30dBFS). Using a 512k FFT length (to lower noise floor of measurement) and RME's ASIO driver (aka Hammerfall DSP).

Pretty neat that I now know conclusively that the RME's volume control is absolutely never going to be the bottleneck in my setup. RME's implementation is discussed here: https://www.rme-audio.de/english/techinfo/hdsp_tmhard.htm

I have to say, I am really liking REW's RTA feature. A special thanks to Ray's for getting me started with the right settings.

 

[RayDunzl]

Short thread: https://www.avsforum.com/forum/91-a...measuring-ambient-room-noise-below-20dba.html

"I used a Lewitt LCT-550, Motu 624 and a CM-140. The 550 is rated for 0db electrical noise and 3dbA acoustic noise."

 

[Blumlein 88]

Short thread: https://www.avsforum.com/forum/91-a...measuring-ambient-room-noise-below-20dba.html

"I used a Lewitt LCT-550, Motu 624 and a CM-140. The 550 is rated for 0db electrical noise and 3dbA acoustic noise."

View attachment 19221

That is interesting. I've got a microphone with a 6 db self noise rating (Shure KSM44a). I'll have to try it vs the Umik. I also have an earlier version of the Lewitt 540 which was rated at 8 db self noise. And the 6 db mic is multi-pattern. 6 db is for omni, but it is 4 db for cardioid (which the 550 is as well).

 

[MrGoodbits]

I followed instructions and could hear (just barely) the 70dB file. That makes me strangely happy. Only you guys would understand why.

 

[wadec22]

@Blumlein 88 thanks! this was fun to try!

I think my setup is pretty typical. I can hear the 70db at normal listening levels (barely). Obviously cranking my desktop setup I can faintly hear the 90db.

This does change perspective looking at the SINAD tables. Basically take anything 90db+, then find the feature set & price combo to best suit your needs and good to go.

Probably not to different from cars. Most on the road can certainly go fast enough for 99% of use cases. All about price & features.

Still very fun to search for impeccable engineering.