29-Mar-2018, 17:49
(29-Mar-2018, 13:37)Confused Wrote: [quote pid='73726' dateline='1522321756']
As for objective measurements, I did actually attempt this last weekend. I had a collection of test tones at various frequencies, and was armed with both an iPhone with Decibel X app and a professional sound pressure test meter that I managed to borrow from work. The idea was to keep the amp at a set fixed volume, test meter in the listening position, run through the tones and check the SPL. This could then be repeated with the mR in the system. This almost worked. The problem was that you could do the test, then repeat it immediately afterwards with no change to the kit whatsoever, and get slightly different readings. For this to produce a valid result, it would need to be repeatable to within 1 dB, but this seamed to be impossible. Even the professional meter seamed to behave very oddly with test tones. It might be reading 75dB, and just walking behind the meter would cause the reading to move maybe 3 dB, walk away and it would hold the reading at the changed level, most peculiar! Interestingly, the iPhone Decibel X app displayed similar behaviour. So the final data lacked proper integrity, it did hint at the mR being slightly 'darker', but I knew that the accuracy was not good enough and I might be reading the results with a degree of bias. What I would really like to do is some REW curves, but I do not believe this is possible via the mR or SOtM kit. If it is possible, could someone tell me how!
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Confused, If you have 2 computers it's not that difficult to generate the REW curves through the whole chain (once through mR and once through SOtM kit) in order to compare them.
@SwissBear was once kind enough to provide me with the process:
1. Use the Generator function of REW to generate a measurement sweep and
save it as .wav. Repeat the procedure for each of the speakers and do not forget to include the timing signal.
2. Import these .wav into a player on your system (JRiver for instance)
3. On the machine with the measurement REW, select a fake output for REW
4. Select 'Measure' and make sure you have the same
parameters (sweep length, aso) you selected for generating the sweep. Also select 'Use acoustic
timing reference'. Click measure. The system will wait for the timing signal.
5. Play the recorded sweep. The system will measure the recorded sweep,
played through your complete system, including correction impulses in
case you have some.
Unfortunately I am not now able to upload the screenshots showing this
