Topic: SD7xx Tone Generator

[OOK]

Scroll to the bottom of the page...

http://www.sengpielaudio.com/calculator-db-volt.htm


There is no decibel to dBFS converter
 
Notice - Comparing dBu and dBFS: There is really no fixed
world standard like e.g. −20 dBFS = +4 dBu = 0dBVU.
The digital peak scale is not equivalent to the analog RMS scale.
 
You can never match dBFS and dBu.
 
dBu is volts - you measure it with a volt meter. dBFS is in contrast a binary number.

[page]

dBu is volts - you measure it with a volt meter. dBFS is in contrast a binary number.

no shit. Thats why I said acquire:

1) What is your 722 set to output on (is there any pad, if not, then the tape out is one value and the mini-xlrs are +20dbu). It's a setting in the menu.
2) What's the max input on the r09hr?

If the max output of the various outputs of the 722 are known in it's specifications (page 69 has the mini-xlr at least), and you don't have a pad (as noted in #1 and noted on page 70 of the manual) then 0dbfs = a known number in dbu. You'll need a similar conversion for the r09hr's input since it's not a 722 which is what you elegantly pointed out with this:

Notice - Comparing dBu and dBFS: There is really no fixed

Which is completely true since maximum inputs/outputs vary across manufacturers/models. So once you go from the 722's output (convert your dbfs to the dbu which you can figure out given the appropriate specs noted above) then you need the max input of the r09hr or the unity setting (so with no extra gain/attenuation you can find what is the max dbu signal the adc can take as it hits 0dbfs). Thus you can say when the 722 has a dbfs rating of X, you know that you should see a dbfs rating of Y on the r09hr. Those don't have to be the same (since the input of the r09hr is unlikely to be the max out of the 722), and you only need three of the four values to make it work ("solve for X" as algebra teachers everywhere say). Once you have the missing value, you can start to calibrate other gear to the r09hr. Now, lots of people have done this homework for you already so finding these values isn't particularly difficult, but if you were to do it at home, thats how you'd do it (assuming you don't have a tone generator with a known signal level) which is easily better then saying -12dbfs is the same on all recorders regardless of what signal it's pumping out on one and what the sensitivity tolerance is on the other which is sort of what you're implying you did when you replied to john with this:

How did you do this? I assume line out of the 7xx and into the R09 and then adjust the level until it matched -12? I would think that the 7xx output would add gain but maybe not.

That is exactly how I did it.  It doesn't add gain but you can set the level tone to whatever output you want.  I did -12 line out of the SD to line in of the R09HR and adjusted the R09HR till it read -12 on its level meter.  When that was done I checked -20 and sure enough it read -20 on the R09HR.  very cool feature....