REW Beta Release 1db difference in SPL meter between Win 10 and Win 7?

[Dush]

Latest beta 9.

Loving Room EQ wizard, it's really revolutionised my setup!

I'm trying to get my reference volume bang on after Auddssey made a mess of it after getting new speakers. Have a UMIK-1 with the calibration file and sensitivity data in there at 90 degrees. Pegged all channels to 75db on my Win 7 machine.

Flipped over to my Win 10 machine 30 seconds later to check and they all seem to be 1db less.

I didn't mess with the input trims on the UMIK because I believe REW takes that into account.

Is this a bug? Or user error (most likely!)

Obviously 1db isn't a big deal but I'm seeing some huge differences between UMIK-1 and the Auddssey mic in setting trims. The UMIK seems to be accurate because when I turn it up to reference it isn't uncomfortably loud and more like a real cinema. But the delta is quite large - see attachment

Thanks

 

[John Mulcahy]

Win 7 and Win 10 treat the volume setting differently and the UMIK gain control adjusts in 1 dB steps, so a 1 dB difference is possible depending on the exact volume setting for each.

 

[Dush]

Ah thanks for confirming.

Is the win 10 one more accurate? 1db doesn't sound like much but when you have 12 speakers it adds up!

 

[John Mulcahy]

Neither is more accurate particularly, they just differ slightly in the exact volume setting values at which the UMIK gain is switched by another dB. The volume control setting is reported to Java (and REW) as a figure from 0 to 1, when you are on the threshold between two of the 1 dB steps a 0.001 change in the volume setting will adjust the UMIK gain by 1 dB. There are places in the volume control range where REW could think the UMIK gain has a certain value but it is actually 1 dB different.