Audyssey setting subs low Vs spl

stevos

Distinguished Member
Hi, any ideas on the following?

Every time I run audyssey it seems to set the subs around 5-10db lower than the other speakers based on SPL meter. I have rerun it several times and tested the volumes using an old radio shack SPL and also using a umic 1 and rew using its inbuilt spl and both show a significant drop in volume for the combined sub channel.

I am assuming there is a nul or something at the main listening postion, but wondering if anything else could be to blame and if there are any ways to potentially fix the cause without moving the two subs (lack of placement options)?
 

dante01

Distinguished Member
Your average SPL meter cannot accurately measure the sound pressure level associated with the output of subwoofers. It is unlikly that you'd be correctly levelling a sub relative to your other speakers and reference if using most SPL meters. You'd need at leat a Pro grade meter probably with Z weighting to get accurate measurement relative to a sub's output.

It may not look very fancy, but the audyssey mic is surprisingly accurate. There are instances where it has proved to be as accurate as a pro grade mic when independently tested.

All-in-all, you are not going to get an accurate subwoofer SPL measurement unless you've an expensive pro grade handhel meter.

If the level difference were due to a nul then both the Audyssey mic and the handheld SPL meter would be subject to the same nul unless you were measureing the sound pressure from two entirely different locations? If this were the case them one of those locations woudn't be your seated listening position so wouldn't really be relevant anyway.

The subs level isn't likely to be set the same as your passive speakers any way. The sub has its own power and onboard amplification. Why would you expect the correction level to be the same as that associated with the passive speakers being powered by the AV receiver?

If it is a null then you can only really either move where you are seated or move the sub. If seated smack bang in the middle of the room then this isn't the best place to be relative to the sub's output and could indeed result in nulls. There are room treatments that could improve things, but using bass traps will also require the space needed to accomodate them plus the effect they will have on the room's decor. Resorting to room treatments and bass traps would really be the only other option if unable to move or relocate the sub. Nuls are caused by the room's acoustics and cannot really be counteracted or accounted for using processing.

Is the bass actually better or stronger elsewhere in the room? If not then it isn't likely to be a null.
 
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stevos

Distinguished Member
I was thinking that but watched another YouTube vid last night (youthman) and like ones I have seen in the past he used a normal SPL on all speakers, just changed the weighting for the subs. Oddly if I changed the weighting like he did I would have to boost way way further to get the same 75db.

I can see that the old radio shack wasn't be accurate but would think a umic1 would be pretty good
 

dante01

Distinguished Member
The reason you'd use a umik mic with REW is because you'd get access to its calibration profile and be able to load it into REW. The Audyssey mic's profile is the profile on which Audyssey itself would be working with in association with that AV receiver.

What REW gives you is not necessarily a more accurate reading, but a more detailed one. You'd use it to determine where the peaks and troughs are post the Audyssey calibration. This would then allow you to manually adjust the EQ on the AV receiver in order to try correct or adjust them.
 
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stevos

Distinguished Member
I've taken a photo of the previous levels and going to live with the adjusted ones for a week or so, to see if overblown or if sound better..

Plan to run a REW measurement of the sub /cross over tonight to see if there is now a big jump in volume as it goes through the cross over or if it's fairly flat
 
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