# dBU and dBV recording

Started by June 28, 2009
Hello,

Is there any relation between dbu and db/dbV.

I have IO box with option of Hi-Gain, +4dBu gain and -10dBV gain.
Basically these are hardware switches present in the IO box.

What does +4dbU recording actually mean?

What does -10dBV recording actually mean?

While performing recording of a file, I found that @ -10dBV recording, the
recorded file used to get clipped, what might be the reason?

Is -10dBV recording has more gain when compared to +4dBU gain?

Rohith M P
dBu is a logarithmic voltage ratio with a reference voltage of V0 = 0.7746 volt ≡ 0 dBu
dBV is a logarithmic voltage ratio with a reference voltage of V0 = 1.0000 volt ≡ 0 dBV
+4 dbU = 1.228 volts
-10 dbV = 0.3162 volts
http://www.sengpielaudio.com/calculator-db-volt.htm

BTW, it is the first page that Google returns on dbu and dbv relationship request.

--
Alexander
Rohith,

I haven't seen a reply to this, so here goes.
[Actually, this is an ANALOG concept. As such it doesn't really belong on a "DSP" list but any way...]

Decibels (dB) are *relative*, comparing one measurement to another. The suffixes added to the dB, such as dBm, dBu and dBV, are, in this case, meant to add a reference, making the measurement relative to a standard other than decibels.

In the case of dBm, it's 1 milliwatt of power on a circuit of 600 Ohms impedance to equal 0 dBm.

This type of measurement was relevant when the systems in use were designed to transfer power over a circuit of specific impedance, such as was the common case when the state-of-the-art was tube equipment and transformers.

Electronic audio design has changed over the years so that almost all audio transmission from one place to another is generated by a source of very low impedance, sent to a load of relatively high impedance, such that *power* is no longer an important part of the equation.

Enter "dBu." The "dBu" spec works identically to dBm when the source/load impedance meets the old dBm spec, but since its reference is to a specfic *voltage* rather than power, it also works when the impedance is unspecified. That voltage, by the way, is 0.775 RMS for 0 dBu.

In the case of dBV, it's similar to dBu, but relative to one volt, to equal 0 dBV.
David Reaves

Sun Jun 28, 2009 8:59 am ((PDT)) "Rohith MP" r...@lntemsys.com mp_rohith wrote:

Hello,

Is there any relation between dbu and db/dbV.

I have IO box with option of Hi-Gain, +4dBu gain and -10dBV gain.
Basically these are hardware switches present in the IO box.

What does +4dbU recording actually mean?
What does -10dBV recording actually mean?
While performing recording of a file, I found that @ -10dBV recording, the
recorded file used to get clipped, what might be the reason?
Is -10dBV recording has more gain when compared to +4dBU gain?