Anthem MRX710 : subwoofer level obviously too low

[MiP]

Hi,

it's my first post here so here is a quick overview of my audio setup before asking my question.
I own a Anthem MRX710 associated to Monitor Audio GX50 bookshelves in front scene and Monitor Audio Silver 50 bookshelves for surrounds.
Low frequencies are handled by a SVS SB13 ultra subwoofer and crossover is simply set to 80Hz. Listening/viewing position is in the living room open to the kitchen, no passive treatment.

Some time ago, I ran a new calibration with integrated ARC and surprisingly it founds my subwoofer volume really low which ends up by setting the AVR level for the sub line to +8dB. I initially suspected the room being the culprit
I re-ran the calibration more recently and quickly noticed the subwoofer sweep noise is played at an obviously lower volume than for the rest of the speakers.
So, I tried REW for comparison and everything is correct from volume perspective. I mean, with REW and 75db target, my SVS master volume is set to -15dB with a AVR sub line reset to 0dB while I need to increse SVS master volume to -8dB when running ARC, which also increase sub level to +3dB to reach the 75dB target. Really feels like there is a 10dB difference as if I miss the LFE 10dB boost for Dolby/DTS

That being said, I'm wondering whether there might be a compatibility issue between ARC Genesis (using latest version with latest firmware) and my 'old' generation AVR, which originally used previous ARC-2 software.

 

[Todd Anderson]

That's odd.

Can you run a sweep with ARC, and capture it by recording your laptop screen while running RTA on REW? Would be interesting to see what it measures.

 

[MiP]

I've just realized my SVS has a switch for input line to select either "high level" or "normal" setting. It is set to the former which does not seem right. Indeed, from SVS manual, normal is for consumer voltage range (2V rms) while high is for pro equipment (4V rms). Likely, I unadvertedly touch it when doing some sub placement trials .
I haven't time yet to redo measurement with the normal setting but I guess it could be the culprit here. will do it tomorrow.
Regarding the difference between REW and ARC, I can imagine REW test sweep (at -12dbfs) is louder than the ARC one but it's just pure speculation, I have no technical background to judge

EDIT: SVS support just confirmed :

The "Hi-Level" setting introduces a -6dB pad to reduce input voltage for use with professional sources. "Normal" is recommended for consumer devices.

 

[Todd Anderson]

Aieee! Simple solution. Glad you found it... please drop in with what happens with your next measurement!

 

[MiP]

Just did a new ARC measurement with "normal" and as expected, all is back to normal
Subwoofer master volume is set to -10dB now and ARC ajusted its level by just -1dB.
By the way, SVS support told me it would have been also fine to have its volume set to 0dB based on the amplifier gain structure, so I tried it first but ARC tamed sub level almost to its maximum attenuation to -11dB.
I'm not really surprised though, considering the size difference between the SVS and the Monitor Audio, which have limited sensitivity

 

[Todd Anderson]

Well this is a happy ending!