Setting gains @ 56db instead of 72bd

[Alex2507]

Setting gains @ 56db instead of 72db

For a goof I ran my test tones at the volume setting that I normally listen at and noticed that the SPL meter was all over the place. I then adjusted the gains to put out equal db's at that volume. I want to see if there is some reason that I shouldn't do this. TIA

 

[bpape]

If the levels are different at the 2 different volumes, it could be that your room has a high enough noise floor to be contributing at the lower relative volume.

Bryan

 

[Alex2507]

Why would the balance shift at different volumes?

Is this normal due to room acoustics or something? Has anybody else tried to run test tones at different volumes and come up with different results? I understand that 75db for a referance level is to keep your max listening volume at a safe level to prevent hearing damage, right? What about keeping it balanced at my normal listening level? Wouldn't that take care of both requirements? Some insight on this would really be appreciated. Thanks.

 

[Alex2507]

If the levels are different at the 2 different volumes, it could be that your room has a high enough noise floor to be contributing at the lower relative volume.

Bryan

Sorry, you got this reply in while I was typing. I'm slow on the keyboard. I set it at the lower volume @ 6:00 AM so the place was dead quiet. I take it that all things being equal my gains should not change?

 

[bpape]

All other things completely equal - yes. Any road noise (you'd be surprised how much low level noise from far away can impact things which is why we build quiet isolated rooms), HVAC running, etc. can very easily add 20db (you can't hear most of this change but it's there) to the ambient noise level of the room.

The other things to consider:

Was the mic in EXACTLY the same place? Were YOU in exactly the same place? Any changes in any doors being open or closed?

All of those things can dramatically effect the balance. When taking relative measurements, one must be sure to minimize all other variables in order to get an accurate result.

Bryan

 

[Savant]

There are myriad reasons a higher relative SPL is used for "calibration." Reason No. 1 is to get ample S/N ratio. My guess would be you didn't have enough S and a little too much N.

You may also be hitting the floor on the SLM if you're using one of the RS models (it only goes down to 50 dBA).

 

[Alex2507]

Thanks guys. I'll keep your points in mind and continue to play. Enjoyment is what makes it a hobby as opposed to a chore.

 

[mpompey]

Alex, you are not crazy. Depending on your room, speakers, etc a system calibrated toplay equal @ 75 can be a few dbs off at a lower setting. How far off were they from the reference levels? When I had a JVC receiver I would get 2-3 dbs difference in some of the speakers from my reference of 85 to listening at around 70.

Now with my current setup, I calibrate at 85 then lower and double check the settings at my listening volume of 70. With my Yamaha receiver and new room, the levels are usually spot on.