C-140 hookup problem

[t6902wf]

I got a c-140 and I can not get the Db high enough. It does not appear the Db meter is communicating correctly with the sound card. I can swap in my RS meter and get a measurement with proper levels.

I bought a mono cable for my hookup to the meter, do I need Stereo?

For what it is worth I recalibrated the sound card
Here is the graph


Here are two measurement runs one with the meter on fast one on slow.



Any help is appreciated

Bill

[t6902wf]

I had some time to do some reading. My USB sound card has a 1/8" line in jack.
In the hookup instructions it says I need to convert the mono line out on the C-140 meter to stereo line in on the USB sound card.

Is this correct? Will it fix my problem? The Meter was registering 75+ db's during the sweeps yet the program said I was not exceeding the high 50's?

Additional questions.

Meter setting db range 50-100
Speed fast or slow
Weighting A for sub, C for full range?

What is the SPL meter on the screen for? It always appears to have low erroneous measurements.

Thanks

Bill

[brucek]

I need to convert the mono line out on the C-140 meter to stereo line in on the USB sound card.

The soundcard line-in jack is stereo, so you need to break-out the left and right channels with an adapter. Then you will connect the mono CM-140 signal to the right channel only of the soundcard.

Speed fast or slow

Slow.

Weighting A for sub, C for full range?

C-only.

What is the SPL meter on the screen for? It always appears to have low erroneous measurements.

It is accurate if you had correctly run the Calibrate routine immediately after setting the REW input level in the Check Levels routine. How else would REW know what 75dBSPL at the listening position is...

Read and become familiar with the REW HELP files and the REW Cabling and Connections Basics.

Also note the REW information Index and the Download Page.

brucek

[t6902wf]

Thanks Bruce.

I was standing in front of the adapters at Radioshack when my phone buzzed with the notice that the thread had been added to. You saved me a trip.