Volume too loud during sweep

[jpv]

I have been using REW for a few years now and I am embassed to ask this but I can't figure this out. I know is a simple solution but..
What is happening is I left my SPL meter on and drained the battery so I replaced it with a new one.
When I went to do a new measurement I did the calibration to 75db first but when I did a sweep the volume was so loud well about the 75db set during calibration. The clipping message came up and the graph was in the high 80's.
I leveled the sound card again and have it set according to the program -18 output, -12db left and right. callibrates for main speakers. I'm using speaker out and line-in.
It's connected to my pre amp and the volume is set there to read 75 db on the radio shack meter.

so what going wrong Help!

[Drudge]

I had a similar problem were my RS meter would measure below what the SPL level really was(about 10dB),I found at times the needle on the meter would get stuck at 0dB even when you would yell into it!

I just couldn't trust it to be reliable,so I replaced it with the ECM8000 mic and a preamp and have had no problems since.

[brucek]

I did the calibration to 75db first but when I did a sweep the volume was so loud well about the 75db set during calibration.

You likely calibrated with a pink noise that didn't represent the end frequency limits of the measurement sweep. That's why the double check "Check Levels" button is available on the measurement panel. The "Check Levels" button on the measurement panel uses the end limits as its cut frequencies rather than the conventional pink noise.

brucek

[jpv]

I did the check level and I say's the volume is OK. That volume is OK and reads 75 db on my digital radio shack meter. Them I go to do a measurement the volume in much louder then when I calibrate it or do a check level. I have to lower the volume on my PC from when I set the calibation so it's not so loud and displays it in the correct range.
John

[brucek]

Them I go to do a measurement the volume in much louder then when I calibrate it or do a check level.

Shouldn't be, if the limits of the sweep match the pink noise limits you used to do the Check Levels.

brucek

[laser188139]

You might want to consider this as two separate questions:

Is the sound level actually higher when you take a measurement than when you calibrate the levels? If so, see Bruce's advice that Check Level operates differently on the measurement screen than on the overall calibration. (Thanks for the observation, Bruce. I did not put one and one together to realize that the Check Level during measurement would take into account the chosen measurement range. That's cool.)

Does the reported level on the graph appear higher? This may be an effect of the averaging in the SPL meter over the whole range. Or this may be come from manufacturing variation in the RS meters. My experience parallels that of Drudge above; after buying an EMM-6 meter with its own calibration file, its measures are different in overall level than the RS meter, even following the same level setting technique. Interestingly, measurements I took with the RS meter as a C-meter without the calibration file parallel the EMM-6 results much more closely than those I took with the RS meter calibration file loaded. So the calibration file provided here on this Forum may be typical, but I think there is still significant RS meter variation.

I found I could learn a lot about what I was seeing without have perfectly calibrated levels. More important was the frequencies of the peaks and valleys, and being able to compare before and after measures during a session without changing any of the settings. You can adjust the graph lines for level differences with the Trace Offset in the Trace Adjustments.

Good luck,
Bill

[glaufman]

Where do you have the range dial on the RS meter set?

[jpv]

I have it set for the 80 db range. I will try again tonight to see if I can figure this out.

[jpv]

OK I said I was missing something small and stupid. I had the loudness button cheched on the soundcard settings. I unchecked it, recalibrated and I'm back in busimess .

Thanks for all the help.
John

[glaufman]

jpv wrote:

OK I said I was missing something small and stupid. I had the loudness button cheched on the soundcard settings. I unchecked it, recalibrated and I'm back in busimess .

Thanks for all the help.
John

Glad to hear it's working out...