Confused Between Average and Peak Voltage Levels

Robert Katz

Hello Bob


I hope you are all doing well in these crazy times ,-)
I’m writing to you regarding an issue where hardly anybody can give me a satisfying answer (hoping you can):


I’m currently demoing a Manley Massive Passive EQ and I also own a Vari Mu already. Manley specifies the adequate operating level for their equipment with +4dBu ! That’s the issue because I’m not aware of any current ADC nor DAC that is made for such a low op level.
I’ve talked to EveAnna Manley and she insists of +4dBu being the world-wide standard…to my knowledge that was in the 80-ies and it was a broadcasting standard
.


I own a Crane Song Solaris that has a fixed output @+18dBu and an attenuated out that goes to a max of +24dBu and can be tuned all the way down to -44dBu or so… But that is made for use as a monitor control and I can hear a bit of degradation in the depth and stereo image when turning it down.


When driving the Massive Passive @+18dBu, it acts almost like a compressor. It doesn’t distort, but it flattens the sound noticeably.
How do you handle operating levels in your studio and what the rest of the mastering world doing with the (very popular) Manley gear ? I know that for example Bob Ludwig uses a lot of Manley equipment…
When I really attenuate the Solaris output down to +4dBu I literally can see my noise floor rising up about +20dB.Also all my other analog equipment isn’t made for such low levels. For example the Knif Pure Mu doesn’t get enough signal to start compressing…
What can I do in order to get that kind of equipment integrated in a way that makes sense ?


Thanks a lot in advance

Best Michael

Dear Michael:

You’re getting confused between average (nominal) levels and peak levels. 

+4 dBu is far from being a low operating level. Many would consider it high. Typically you make +4 dBu be either -20 dBFS or -18 dBFS with a sine wave test tone. At that point the peak level will be +24 or +22 dBu, which is hardly a low voltage! 

The Solaris output of +18 dBu is the rating at 0 dBFS, full scale. You need to have an audio-grade voltmeter that reads in dBu and then everything will become clear to you. 

I hope this helps,

Best wishes,

Bob