Does anyone have a design for an in-line +20dB gain lifter for a balanced mic.
It would need to be fed from the 48v phantom power with low noise & high headroom etc. similar to the FET-Head or cloud lifter.
Thanks.
R.
It would need to be fed from the 48v phantom power with low noise & high headroom etc. similar to the FET-Head or cloud lifter.
Thanks.
R.
I've done unbalanced inline 48V powered DI, mostly for guitars to desk. I had 2 versions a +6db and a +20dB depending if the the guitar had active electronics.
the source for this is always a unbalanced instrument w/o need for phantom powering, although I also built 48V phantom powering for acoustic guitars with electronic pickups, to avoid the battery empty stress; Using a stereo TRS plug to access the ring that is used to short to gnd in the guitar to activate the internal guitar battery. I'm not sure if your requirement is for phantom powered mikes, these usually have sufficient sensitivity. passing on the phantom power to the input is not a trivial thing while amplifying the signal . If you need to amplify less sensitive dynamic mikes or ribbon types, then a balanced to balanced amplifier is needed. My first idea would be to use an input transformer to higher Z input and then a balanced buffer, let the transformer do the gain.
A bit of googling "FET-Head" digs up several designs, i.e. https://groupdiy.com/threads/diy-inline-preamp-triton-fethead.74048/#post-937600
Wouldn't that already do what you need?
the groupdiy design is interesting. first you need 2 types of 2sk170 for the cascode to function properly with different idss classes . second the fet max vds = 40V less than the 48V phantom supply. This can be a problem when cold inserting the amp to the desk.