Originally Posted by whoaru99
I believe this is the root of all confusion in this deal. It seems they're being held as abolutes when, in fact, they're not.
, or maybe it's IMO, those numbers actually refer more to line level input/output signals like between a tape deck and recording console or preamp, not the connection between preamp/mixer output and power amp input.
It is worse than that. Consumer equipment uses dBV, and pro equipment use dBu.Link to dBu and dBV
"In the analog audio domain there are primarily 2 db scales of importance:
dbu and dbV. These scales describe voltage ratios. The difference are the reference points:
dbu: 0 dbu = 0.775 V (u means "unloaded")
dbV: 0 dbV = 1 V
Both scales can be found in the definition of standard reference levels of consumer and professional products. While the standard reference level for consumer products is -10dbV, the reference level for professional audio products in +4dbu."Link to calculation of dBu and dBV levels
"A side trip -- "Professional" vs. "Consumer" Levels
There has always been a lot of confusion about the whole issue of the nominal operating level of "professional" gear versus the nominal operating level of so-called "consumer" gear.
You may have heard that professional gear is "+ 4 dBu" and consumer gear is "- 10 dBV." Because only professionals used this stuff back when it was new (and expensive!) technology, and the older dBu designation was all they had to work with, the original designation of operating level (expressed in dBu) has stuck. By the time consumer audio products were introduced in a big way, the dBV has been invented, and so dBV was used for consumer gear. (Remember, they are both simply ways of comparing voltage levels -- nothing more. That + 4dBu is somehow inherently "better" than -10 dBV is a big, fat myth, kept alive by the somewhat arbitrary labels of "professional" and "consumer" attached to them.)
I'll just bet that a lot of you have glanced at this "+4 / -10" thing, and just assumed that the difference between the levels is 14 dB. But now we know better, don't we?
The reason the difference isn't 14 dB is because the reference levels between dBu and dBV are different! Remember, dBu is referenced to a voltage level of .775 V, and dBV is referenced to 1V. Armed with the knowledge you now possess, can you figure out what the true difference in operating level is, between + 4 dBu and -10 dBV?
+ 4 dBu = 20 * log (voltage / .775 V)
voltage = 1.228 Volts
- 10 dBV = 20 * log (voltage / 1V)
voltage = 0.3162 Volts
20 * log (1.228V / 0.3162V) = 11.79 dB
You can confirm this by doing a little experiment. Plug a piece of consumer gear with -10 dBV outputs into a piece of gear with + 4 dBu inputs. If they both have VU meters, calibrated such that 0dBVU on each piece of gear corresponds to it's nominal operating level, you'll find that 0dBVU on the consumer gear causes a reading of -11.79 dBVU on the pro gear's meters."