lowerFE Posted November 17, 2015 Report Share Posted November 17, 2015 I have this itching feeling in my mind to find what the CEA 2010 maximum output for the infamous Logitech Z-5500 subwoofer. Is there a way I can do a rudimentary ground plane testing with CEA 2010's testing standards using a UMIK-1 microphone? Is there a guide on how to conduct this? I just want to measure the frequency response, compression graphs, and max burst output. Thanks Link to comment Share on other sites More sharing options...
shadyJ Posted November 17, 2015 Report Share Posted November 17, 2015 There are a couple guides online, Josh Ricci's and Brent Butterworth's. Your mic looks like it should be able to handle down to 20 Hz, although it might be down a bit by 20 Hz. If you have the right equipment, and software, another hurdle is getting the right setting. Legitimate CEA-2010 testing is supposed to be done between 65 to 80 degrees and 30% to 80% relative humidity. You will also want a low noise floor area (no busy streets nearby) that has 60 feet from any building or large structure. You will also need a source of AC nearby. Good luck! Link to comment Share on other sites More sharing options...
lowerFE Posted December 2, 2015 Author Report Share Posted December 2, 2015 The guides show you need a mic preamp for this testing. Is there any way to do this just with a UMIK-1? I tried Igor Pro, but it doesn't seem to be showing the right data from the UMIK-1 (it's like 20dB off). Link to comment Share on other sites More sharing options...
shadyJ Posted December 2, 2015 Report Share Posted December 2, 2015 I thought the USB mics had their own pre-amps. As for your results, everything is calibrated correctly? You are checking everything with an SPL meter? Link to comment Share on other sites More sharing options...
Ricci Posted December 2, 2015 Report Share Posted December 2, 2015 I'm not familiar with the Umik. You need to use a calibrator and the Pa adjustment. Link to comment Share on other sites More sharing options...
lowerFE Posted December 2, 2015 Author Report Share Posted December 2, 2015 I managed to calibrate the mic by having my sub produce an exact 94dB signal, and then doing the calibration in Don Keele's program. Now it has the SPL right, but I can never get a passing result. Here's what it looks like. It always has that "mountain" shape response, regardless of volume. When I use REW's CEA2010 bursts + spectrum graph, I do not see that, and it shows the right spectrum. Link to comment Share on other sites More sharing options...
shadyJ Posted December 2, 2015 Report Share Posted December 2, 2015 If you are doing the testing indoors, there may be something else rattling or vibrating that is causing too much noise at a harmonic in order for your sub to ever pass. I would run some single frequency tones in your room and look at what is occurring at the harmonics in an RTA. Link to comment Share on other sites More sharing options...
lowerFE Posted December 2, 2015 Author Report Share Posted December 2, 2015 If you are doing the testing indoors, there may be something else rattling or vibrating that is causing too much noise at a harmonic in order for your sub to ever pass. I would run some single frequency tones in your room and look at what is occurring at the harmonics in an RTA. This is done outdoors, around 30 feet away from a reflective boundary. The background noise is fairly quiet. However, no matter what volume, high or low, I get that mountain shaped response. Also, on REW's spectrum + CEA 2010 burst tones, I see a proper spectrum. I would provide a screenshot that I have a proper spectrum, but I don't have a print screen key on my Macbook Pro, so I can't capture this. It flashes for a second, and it's gone, so I can't use snipping tool like I did for Igor Pro. I measured my Martin Logan Dynamo 1500X and compared it to Josh's results, and the FR (from REW) and max burst (from Igor Pro) largely match within 1-2dB (I'm consistently over by ~1dB, need to recalibrate mic), so it seems like I'm doing a few things right. Link to comment Share on other sites More sharing options...
Ricci Posted December 2, 2015 Report Share Posted December 2, 2015 I sometimes have trouble with a similar thing at 100 and 125Hz. It is not capturing the full waveform or something. Seems like a timing issue. 125Hz is the problem band for me. I think it is related to the timing but I haven't explored it yet. Your waveform capture is jacked. It shouldn't look like that. Link to comment Share on other sites More sharing options...
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