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Gear / Technical Help => Recording Gear => Topic started by: OOK on January 11, 2013, 09:08:37 PM
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I just discovered that the SD7xx series recorders have a tone generator signal on them. You can set the level and frequency of the tone. I was able calibrate my R09HR to a -12 signal. Which unity gain on the line in is 40. Cool feature.... great for setting your levels on the R09HR then running a preamp into it....
Peace OOK
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I usually use the tone generator on my fp-24 to calibrate gear. Never thought to use the 722...
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It is a cool feature.
But beware. In earlier versions of the firmware the tone button remained active even when the hold was supposedly engaged! I discovered that one the hard way. That may have since been corrected.
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I usually use the tone generator on my fp-24 to calibrate gear. Never thought to use the 722...
I've used it to calibrate other gear before. Definitely one of those features that doesn't get used much, but is real handy when you need it.
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Tone Generator's are on all Sound Devices Mixers too. An essential production tool for professional grade gear, like SMPTE Color Bars are for video.
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I just discovered that the SD7xx series recorders have a tone generator signal on them. You can set the level and frequency of the tone. I was able calibrate my R09HR to a -12 signal. Which unity gain on the line in is 40. Cool feature.... great for setting your levels on the R09HR then running a preamp into it....
Peace OOK
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.
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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....
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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....
well... The lack of math involved here has me worried as to how much benefit you're getting. Maybe you just didn't include that, but I'd check a few things first:
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?
3) What are you setting the tone to (dbfs rating)?
One you get #1 and #3, you can figure out the dbu of the signal as it's leaving the 722, and then once you figure out the max in (which would represent 0dbfs with no gain added). Now, if you already know that the setting of 40 is unity, you can find out what #2 is which is handy in calibrating preamps for maximum output to the recorder (e.g. if a setting of 40 is unity, and you find out that your signal is really +23dbu at that point, then if you preamp only goes to +20dbu before crapping out, add 3db as tested by the 722's tone generator to the r09 so that it clips at the same time as your preamp). It's that last aspect that is particularly handy. That's actually how I found out that the voltage you feed an old sonosax determines where it overloads.
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It is a setting in the menu:
On the SD702 it is menu # 61. I have the level set to -12dbfs
Then the tone is selected by menu #62. I have the tone set to 100hz
Then tone mode is selected by menu #63. It is set to outputs only.
So the SD702 sends a tone to the outputs only of 100hz at -12dbfs.
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It is a setting in the menu:
On the SD702 it is menu # 61. I have the level set to -12dbfs
Then the tone is selected by menu #62. I have the tone set to 100hz
Then tone mode is selected by menu #63. It is set to outputs only.
So the SD702 sends a tone to the outputs only of 100hz at -12dbfs.
ok, so that answers #3. While unlikely, your setting for #1 would create a different output even though it's registering -12dbfs on the unit.
Did you use the tape out or the mini-xlr out?
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It is a setting in the menu:
On the SD702 it is menu # 61. I have the level set to -12dbfs
Then the tone is selected by menu #62. I have the tone set to 100hz
Then tone mode is selected by menu #63. It is set to outputs only.
So the SD702 sends a tone to the outputs only of 100hz at -12dbfs.
ok, so that answers #3. While unlikely, your setting for #1 would create a different output even though it's registering -12dbfs on the unit.
Did you use the tape out or the mini-xlr out?
Tape Output. i don't have mini XLR to mini cable.
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It is a setting in the menu:
On the SD702 it is menu # 61. I have the level set to -12dbfs
Then the tone is selected by menu #62. I have the tone set to 100hz
Then tone mode is selected by menu #63. It is set to outputs only.
So the SD702 sends a tone to the outputs only of 100hz at -12dbfs.
ok, so that answers #3. While unlikely, your setting for #1 would create a different output even though it's registering -12dbfs on the unit.
Did you use the tape out or the mini-xlr out?
Tape Output. i don't have mini XLR to mini cable.
Ok, I'd have to look up in the manual what that is, but I think that's the -10db nominal out, but I can't remember what the peak is. I did the same when I calibrated my sonosax (3.5mm > trs > xlr). It's still doable, but you have to figure out what level it's sending.
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As I understand it the level you are sending is what you are adjusting on menu # 61. It is a fixed level. whatever you are setting it to output is the fixed level. if you send a -12dbfs that what it is sending a fixed tone at -12dbfs. I too just ripped out the manual(page25 in mine, heading is tone oscillator) and it states the tone level is adjustable over a range of -40dbfs to 0 dbfs.
OOK
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As I understand it the level you are sending is what you are adjusting on menu # 61. It is a fixed level. whatever you are setting it to output is the fixed level. if you send a -12dbfs that what it is sending a fixed tone at -12dbfs. I too just ripped out the manual(page25 in mine, heading is tone oscillator) and it states the tone level is adjustable over a range of -40dbfs to 0 dbfs.
yeah, your dbfs is the same, but the output in dbu (which is what the max in on the next piece of gear is looking at) is different based on the connector by 15 or 20db. Different scales and functions.
To put it another way; line in and mic in both take vastly different signal strengths, yet both can register -12dbfs. This is the same thing, the signal you're sending downstream is not only different by connector on the 7 series, but whether you're padding it any is adjustable in the menu settings (all regardless of what the full scale read out on the unit is).
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Interesting thread.
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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.
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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....