Default Sweep Level

[compudaze]

Why is the default sweep level -12? Does it matter if I change it? When playing back sweeps or pink noise at default level, I can only raise the volume of my AVR to -25db before I hit 75db. Is it OK to change the sweep level so I can play them back with my AVR at 0db?

Does any of this even matter?

Thanks!

 

[John Mulcahy]

You can use whatever level is convenient, but very low levels will mean the signal is more affected by quantisation noise as it gets scaled down before sending the data to the soundcard. Unlikely to be a problem unless you find yourself using extremely low levels though.

 

[James Ashton]

I find the default sweep level keeps resetting itself after every measurement. I'm calibrating a room for surround sound audio post production and would like to have a sweep level of -20dB (-12 causes clipping on the UMIK-1 that I am using). After each measurement the value returns to -12dB. I assume this is a bug?

I'm using REW V5.20 Beta 55 on MacOS 10.14.6

 

[John Mulcahy]

Probably the same issue as reported here, the next beta has a fix.

 

[EarlK]

Hi John,

A ( small ) ask ( I hope ) ;

Is it possible to add a button ( or maybe a Right-Click choice ) to switch the db increments choice from 0.1 over to 1.0 steps, when changing sweep levels ( in both the measurement window and generator window )?


Thanks <> Earl .

 

[John Mulcahy]

Is it possible to add a button ( or maybe a Right-Click choice ) to switch the db increments choice from 0.1 over to 1.0 steps, when changing sweep levels ( in both the measurement window and generator window )?

Not easily, but values can be typed in directly rather than changing them using the buttons.

 

[sam_adams]

Why is the default sweep level -12? Does it matter if I change it? When playing back sweeps or pink noise at default level, I can only raise the volume of my AVR to -25db before I hit 75db. Is it OK to change the sweep level so I can play them back with my AVR at 0db?

Does any of this even matter?

If we take a look at the article by Zed Brookes, Digital Recording Levels - a rule of thumb, (you'll have to Google for it since including the link gets this reply marked as spam) regarding digital recording levels we see that the -12 dBFS default level equates to 0 VU (0 dBVU, 0 dBU) when using sixteen (16) bit digitization. My question for John is; if the sound system settings are set to twenty-four (24) bit digitization why doesn't REW change the default level to -18 dBFS (EBU) or -20 dBFS (SMPTE)? This should keep the output levels equal when switching between bit depths. REW does recognize that the system is set to twenty-four (24) bit digitization when the measurement window opens because the notification bar on the lower left of the main window clearly indicates the bit depth and sample rate.

 

[John Mulcahy]

There are usually other level controls in the output path, and the level is just a default - if the user changes it the user's setting applies.