SPL meter bug

[lovingdvd]

SPL meter bug:

1. Turn on SPL meter so it is taking readings.
2. Bring up Generator and select Pink Noise.
3. Choose HD Audio HDMI #0 1.
4. Hit play on generator so pink noise starts.
5. Press stop on generator.
6. Change Output on generator to HDMI out #2 (or any other selection besides the current one).
7. SPL Meter turns off (I don't think this is supposed to happen?).
8. Press Play on generator.
9. Turn SPL Meter back on. After a couple seconds am error dialog appears "No soundcard input data - The soundcard did not provide any input data, please check that it is connected"
10. The bug can be avoided as long as you manually stop the SPL Meter before changing HDMI output channels, and then manully start it after pressing play on the Generator. Ideally we could just change the channel in the Generator and the SPL Meter would just stay on the whole time.

Likewise it would make things easier if we can change HDMI channels while it is playing, rather than having to hit stop, change channel, and then hit play again. Maybe that could be implemented as an enhancement?

Thank you.

 

[John Mulcahy]

I've fixed the 'no soundcard input data' bug for the next beta release. It can also be worked around by starting the SPL meter before the output. The ASIO driver doesn't allow channel selections to be changed while running.

 

[lovingdvd]

I've fixed the 'no soundcard input data' bug for the next beta release. It can also be worked around by starting the SPL meter before the output. The ASIO driver doesn't allow channel selections to be changed while running.

Great, thanks! I'm pretty sure that if I start the SPL meter before the output its fine, until I change the output to another channel. So the workaround in the meantime has been to stop the meter before I change the output each time, then restart the meter. Perhaps that is what you are saying as well.

Regarding the driver not allowing channel selections while running - here is an idea that will be just as convenient... Maybe you can make it so that the output selection is not grayed out when running, and if it is changed when running, REW can stop it automatically upon being changed, and then start it to the new selection a half-second later (or whatever the minimum switch over time would be). This will make it much more convenient when checking trim levels and moving from speaker to speaker to speaker. Perhaps with a full PC and mouse it's easier than it sounds, but on a small laptop with trackpad which I'm using for REW it's a bit awkward having to mouse over to the stop button, mouse to the output list and change the selection, and then mouse back over to hit the play button again. Thanks!

 

[lovingdvd]

John - just wondering if you considered what I wrote in the last paragraph, above?

 

[John Mulcahy]

It's on the list of things to consider.

 

[dc2bluelight]

I find I use the SPL meter and calibrate button a lot for measuring dB differences, setting the meter to "0" using a reference level. The calibration function shuts down the generator, which may make some sense but in my case I would prefer the generator just keeps running because I'm going to use it immediately for my next test.

 

[John Mulcahy]

I've changed the behaviour for the next beta so that REW will only stop the generator after SPL calibration if the generator was started by REW, if it was already running it will be left running.

 

[dc2bluelight]

And this is possibly one of the best features of all of REW....you can make a suggestion for a change, and it's heard!

Thank you!

 

[John Mulcahy]

Regarding the driver not allowing channel selections while running - here is an idea that will be just as convenient... Maybe you can make it so that the output selection is not grayed out when running, and if it is changed when running, REW can stop it automatically upon being changed, and then start it to the new selection a half-second later (or whatever the minimum switch over time would be). This will make it much more convenient when checking trim levels and moving from speaker to speaker to speaker. Perhaps with a full PC and mouse it's easier than it sounds, but on a small laptop with trackpad which I'm using for REW it's a bit awkward having to mouse over to the stop button, mouse to the output list and change the selection, and then mouse back over to hit the play button again. Thanks!

I have made that change for 5.19 beta 10.

 

[lovingdvd]

I find I use the SPL meter and calibrate button a lot for measuring dB differences, setting the meter to "0" using a reference level. The calibration function shuts down the generator, which may make some sense but in my case I would prefer the generator just keeps running because I'm going to use it immediately for my next test.

This sounds interesting and I'd like to understand better. I like to use the SPL Meter and generator so that I can balance all my speakers to the same SPL. Currently I make a note of the front Left speaker's SPL reading, and then change the trims on the other levels to have the same reading. For instance, if the Left speaker measures 76.3 dB, I change the trims so that the SPL reading on the other speakers is as close to 76.3 as possible.

With this in mind, I have a question regarding "setting the meter to 0 using a reference level"... Are you saying there is a way to calibrate the SPL meter, so that it will treat the reading of my Left speaker as 0dB, and with it set like that, I can change the trims on the other speakers so they are as close to 0 as possible? This will just be a little cleaner than trying to remember what my reference level is, versus just aiming for 0 on all trims. Can you explain the process for doing this calibration? I thought the Calibrate button is used to calibrate against something else? Thanks!

 

[John Mulcahy]

Just use the calibrate button when playing the test signal on the speaker you want to use as the reference and enter 0 as the level.

 

[lovingdvd]

Just use the calibrate button when playing the test signal on the speaker you want to use as the reference and enter 0 as the level.

Great. Will it do this based on Leq? For instance, can I have it use Leq to average it out a specific signal level and then 0 it based on that. Then subsequent SPL measurements using Leq will read 0 if matched?

 

[John Mulcahy]

Calibration uses the SPL reading.

 

[dc2bluelight]

Great. Will it do this based on Leq? For instance, can I have it use Leq to average it out a specific signal level and then 0 it based on that. Then subsequent SPL measurements using Leq will read 0 if matched?

Leq is loudness of a varying signal integrated over time so that the reading is equivalent to a continuous signal. If you're calibrating you're already using a continuous signal (band limited pink noise) so you don't need Leq. Just use slow response to make life easier.