Pad math

[notCardio]

If you have a -10db pad on a mic, and a -10db pad on the input of the pre/mixer, and both are engaged, is that the equivalent of a -20 db pad?

And what about rolloff? Let's say that the rolloff on the mic and the low cut on the pre are indentical (I know, it's not ever gonna happen, but just humor me) at 12db/octave starting at 80Hz with the same slope. If both are fully engaged, is the rolloff 24 db/octave?

Help me understand.

Thanks

 

[SS454]

I think decibals are on an logorithmic scale.

 

[jake-owa]

That sounds right to me, except most low cut filters aren't that smooth a roll, more like a hard shelf I think, so the combined attenuation would be all funky. Y'now a combonation of the hard and soft knee...I don't know calculus..lol.
Sounds like you're on the right track although some geek will probably come in here and set us straight.

 

[The Axis]

Basically: (-10 dB) + (- 10 dB) = -20 dB

That is one of the reasons that the dB scale is convenient and preferred for science and engineering.

-3dB = half power
-6 dB = half voltage

 

[notCardio]

Thanks, Axis. And Jake, yeah, I know what you mean, I was just trying to use something as an example.

Axis, just to double-check, the result of any sequential boosts or cuts is going to be the sum of the individual boosts or cuts, correct? Example: two identical graphic eq's in series, set to boost (or cut) the same frequency range, the first set to boost +5db, the second set to boost +4db, will result in that frequncy range being boosted +9db, right? First set to +7, second to -6, would result in a +1 boost, etc., etc. Please correct me if I'm wrong.

Thanks.