HomeStudioGuide.com - Guide to Home Studio Recording

What is the difference between dBu and dBV?

If you've followed my previous articles, dBu is 0.775 Volts at 0dB.

But just to let you know, dBu is the same as dBv (with the lower case "v"). i.e. 0dBv = 0.775 Volts. The National Association of Broadcasters adopted the dBv term for 0.775Volts reference = 0dBv

Now, don't confuse dBv (lower case v) with dBV (upper case V) which is referenced to 1 volt = 0dBV

Now, the good news is today, dBu (with the letter "u") is the preferable usage. That is good... and that would avoid confusion with the use of the letter "V" or "v". 

dBV and dBu conversion factors

You can convert between dBV and dBu since they're both voltages and just have a different reference point. 

The simplest trick is to just add 2.2dB to the dBV value you have.  So, +4dBV = 6.2 dBu

If converting from dBu to dBV, subtract 2.2 dB.

So what does this all have to do with the Home Studio?

Good question! Well, your studio is probably a mix of consumer, and proffesional equipment. The output of consumer gear is normally rated in dBV (i.e. referenced to 1 volt) while professional gear is rated at dBu (referenced at 0.775 Volt). 

Consumer equipment usually have inputs and output jacks that are intended for use with high impedance equipment. These equipment are more sensitive to voltage than power. 

Typical ratings for their nominal level will be -10dBV.  (Of course, now you know what that is in dBu... which is  -7.8dBu )

However, professional equipment are often specified in +4dBm (remember what the "m" stands for???? You forgot? It's for voltage readings loaded with a 600 ohm load.)

So what does this all have to do with the Home Studio - Part 2 ?

Well my good man... it means it's unavoidable to mix and match consumer and pro gear in your home studio. But you have to pay attention to where you plug what.

A low impedance pro gear output can be connected to a high impedance (consumer gear) input without too much change in levels.  By "consumer gear" here, I mean your Home stereo tape recorder and stuff like that. I don't mean "Mackie mixers or Behringer mixers." 

But if you connect a high impedance output (say from your Home stereo tape player) to the low impedance inputs of your pro gear (say your Mackie mixer),  that output may be overloaded by the low impedance of the input, and can result in distortion or bad frequency response. It may even damage your gear (i.e. the high impedance output, in our example, the consumer tape player.) 

So what to do? Use a DI Box. Here are some links to DI boxes you can use.