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Hi Everyone. Steven from Singapore here.

Just started using V5 (build 2142).

Evaluating it to see how well it compares to hardware sound measuring equipment (SPL, THD, frequency, etc).

Right now having a problem with REW's SPL meter.

I am comparing it with a TES 1353H Integrating Sound Level Meter from Taiwan.

When using TES' amplified SPL output, REW tracked the meter very well. It could even compute the SPL faster (seemed like 3 -5 times faster when eyeballing the readings).

However, when using a mic and pre-amp instead of TES, the results weren't as good. I was off by 4 dB in the 66-76 dB SPL range. More error at lower SPLs.

I repeated all the steps used to calibrate REW to the TES except that I unchecked the C-weighting box in the Mic/Meter tab. I also had to add Mic Boost in the sound card (SoundMAX INtegrated Digital HD Audio from Analog Devices) as the overall mic gain wasn't high enough to reach the prescribed -18dB FS level. I am suspecting that the mic / pre-amp (homemade: one AD OP-07 with 10X gain followed by another AD OP-07 buffer) isn't linear enough so I need to calibrate them. (Now while writing this mail, it may be that I should just use the soundcard's mic boost without the external homemade pre-amp ?).

Anyone have any ideas on how to calibrate my mic and pre-amp using REW ? I was thinking of using the Soundcard calibration routine with the mic and a speaker in a quiet space and adding the resulting calibration file (probably need to doctor it a bit) to the Mic/Meter settings tab in Preferences.

PS: I also compared the TES' THD with the mic/pre-amp combination: .5% vs .8% showing me that the mic-pre-amp isn't distorting the signal much compared with the TES.


Microphone: EM-54F(P)-60DB (datasheet attached)
Pre-amp: ne AD OP-07 with 10X gain followed by another AD OP-07 buffer (partial schematic attached)
Soundcard: SoundMAX INtegrated Digital HD Audio from (Analog Devices)
 

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Super Moderator
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Hello and welcome to the forum. Glad to have you with us.
 

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Steven,
Welcome to HTS. So glad you are using REW as it really is a fantastic tool. Good luck with it.
Cheers,
JJ
 

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Welcome to the forum! Definitely post in the REW section of our forum! There are more experts who can help you out there and you will get much better response than in the welcome forum.
 

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Welcome to the Forum. Have fun. Dennis
 

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Hello and welcome, Steven! :wave:

We're glad you've joined and look forward to your participation on the forum...
 

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Glad you could join us, Steven!
 
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