"Check levels" behaves differently depending on frequency range - cause for concern?

[Spennis]

Hi,

I was running sweeps of my subwoofers at two different frequency ranges: 0-200 Hz and 0-24000 Hz. With 0-200 Hz, the "Check levels" reports that levels are fine. However, with 0-24000 Hz, the levels are reported as too low. When running the actual sweeps, the SPL level is the same irrespective of which frequency range I choose (about 100 dB peak). I suspect that "Check levels" uses the frequency range you choose for your measurement (?), which would explain why the output level would be lower for a subwoofer if the range is set to 0-24000Hz than if it is set to 0-200 Hz. However, can I safely ignore the "levels are too low" warning if I want to run a 0-24000 Hz sweep?

Regards
Isak

 

[John Mulcahy]

I suspect that "Check levels" uses the frequency range you choose for your measurement

Yes, it uses either a sub or speaker cal signal according to the range of the measurement.

However, can I safely ignore the "levels are too low" warning if I want to run a 0-24000 Hz sweep?

Yes, though I'm not sure why you'd want to measure a sub to 24 kHz and there will be a reduction in the measurement signal-to-noise ratio since much of the response will be below the noise floor.

 

[Spennis]

Thank you. Measuring 0-24000 Hz was a lazy solution to not having to adjust LFE levels in my AVR when doing a full manual Atmos calibration and not having the number of samples being reduced in the subwoofer measurements as compared to the rest of my speaker measurements. I have however learnt that the latter issue can be resolved with the "decimate IR" setting in REW.

Given what you are telling me now, I suppose I shouldn't be lazy and do 0-24000 Hz on my subs.

 

[John Mulcahy]

Measuring 0-24000 Hz was a lazy solution to not having to adjust LFE levels in my AVR when doing a full manual Atmos calibration

Not sure what you mean by that, but have you seen the options available if you have LFE as an output channel? REW can automatically change the output level and end frequency when the LFE channel is measured.

 

[Spennis]

Not sure what you mean by that, but have you seen the options available if you have LFE as an output channel? REW can automatically change the output level and end frequency when the LFE channel is measured.

View attachment 67550

Yes, thank you. Denon/Marantz AVRs boost the LFE by 10 dB, and I was told that doing a 0-24000 Hz sweep instead of 0-200 Hz would negate the need to manually adjust the LFE output level by -10 dB (with the purpose of SPL aligning all speakers including subwoofers).

 

[John Mulcahy]

Denon/Marantz AVRs boost the LFE by 10 dB

All AVRs do that, it is part of the LFE specification.