Timeline for Converting dBV to dBSPL
Current License: CC BY-SA 4.0
12 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Dec 2, 2023 at 14:34 | vote | accept | Tom | ||
| Nov 27, 2023 at 21:10 | answer | added | qrk | timeline score: 1 | |
| Nov 27, 2023 at 17:08 | comment | added | Justme | What opamp? This is first time I heard about an op-amp. I thought there was simply a mic with voltage out and that was converted to digital, with +1V from mic being +32767 as 16-bit value. Well, you can either use opamp gain as linear or convert it to dB too. That's 26.95 dB, can round to 27dB. | |
| Nov 27, 2023 at 17:03 | comment | added | Tom | How do i know everything? Explain then how would i convert every value from V to dBSPL if not taking the gain of the opamp, the sensitivity of the mic and the offset for dBSPL into consideration? Here is an example of others that had this issue: electronics.stackexchange.com/questions/375869/…. Somehow, im not getting 94 dBSPL as expected, but instead 69.68 dBSPL using the formula above. In detail: -57.5 dBVrms - 4.82 dBV (gain) - (-38 dBV) (sensitivity) + 94 dBSPL = 69.68 dBSPL. (i calculated the gain using ltspice bode plot of the schematic) | |
| Nov 27, 2023 at 16:47 | comment | added | Justme | 1V is also, by definition, 0dBV. And then you know everything in both dBV and dB SPL, because you know the relation of 32768 to 1V, 1V to 0 dBV, and dBV to dB SPL. Sorry but I don't understand which part of the puzzle you think you are missing. | |
| Nov 27, 2023 at 16:33 | history | edited | Tom | CC BY-SA 4.0 | Updated code |
| Nov 27, 2023 at 16:31 | comment | added | Tom | I dont want to convert just -38 dBV to dBSPL. That is pointless at this point. I want to convert ALL values to dBSPL. After researching on this topic i have found, that i need to calculate with the gain, sensitivity and dBSPL like this: X_dbSPL = X_dbV - Gain - sensitivity + 94 # dBSPL. I have included the code above. | |
| Nov 27, 2023 at 16:22 | comment | added | Justme | It has been said many times now that mic data sheet says -38 dB(V) equals 94 dB(SPL), but I don't know why you are unable to make that connection. | |
| Nov 27, 2023 at 16:18 | comment | added | Tom | Lets assume 32768 actually equals 1V. Furthermore, i have calculated the gain of the opamp to be $1+\frac{R_f}{R_in}=1+100/4.7=21.27$. Yes, the sensitivity is -38 dBV. How can i then get the dBSPL? | |
| Nov 22, 2023 at 17:57 | comment | added | Justme | This is already extensively discussed at dsp.se. And there are similar questions here. The manufacturer data sheet clearly says 94 dB(SPL) equals -38 dB(V), so there is an offset of 132. Now, for some reason, you assume 32768 is 1V, which may or may not be true. Just because an ST employee said so on a support forum (and was wrong on other points before that as well) it might not be true. | |
| Nov 22, 2023 at 17:46 | history | edited | JRE | CC BY-SA 4.0 | edited body |
| Nov 22, 2023 at 17:36 | history | asked | Tom | CC BY-SA 4.0 |