I notice my mixer seems to have a bit of gain even when the knobs are all turned down...
Compared to my dbx preamp which I can turn all the way down...
Why the inherent gain on the mixer? Does that mean that mixers preamp sucks?
Its just because its hard to design a single preamp knob with 60 db of gain on it that goes from 00 to +60 db. So some have there gain range set to -50 to +60. Some mixers have -50 to +60 + a 20db pad that subtracts 20db from the input giving you a range of -70 to +60 good enough for most things. You can however mod a board that does not have a pad and put one in so you can pad down the input. There is also another way to do it by using the mixers channel insert point and adding a 10k pot to it and connecting it to the send and return now you will be able to dial down the mixer by at least 20-30 db right after the gain control. Seems counter productive. The main thinking behind this design of a gain pot is what is the mixer most likely to be used for. For example on a professional mixer we have a -20 db pad because for a channel that is used for Kick drum we might have to pad the input down before it gets to the first gain stage inside the board. And then there is the snare drum pretty much always have to pad that channel down. But when its a small mixer they skip the extra wide gain control. Because your not likely to use for example a 4 channel board to mic a drum kit. So there are workarounds to your problem it all depends on how bad you want to fix it
The other reason why they don't put in single pots that do from -70 to +60 is noise floor. Having a high value pot like that in the gain stage introduces noise into the front end of the preamp.
The DBX is a rack mount so you only have to deal with two channels its not as much of a big deal for noise floor because there is less electronics inside the preamp rack then there would be in a console. So they can design gain pots that have full travel its also cheaper then having to add a pad on the dbx preamp if it does not have one. The danger in this type of design is that the first stage can still be overloaded with out a pad to lower the input before it reaches the first gain stage. This is the whole delima with digital recording devices with digital attenuation the first stage can still be overloaded I wish more companies would put a simple resistor pad in the front end of there recorders then you would not have the overloading problem that is so prevalent today.
Chris Church
Topic: Channel Strip vs. Straight Preamp (Read 2620 times)