Muso terminology query

Mid scoop is an EQ function - "to scoop out" a load of the mid-range frequencies. Ground lift is something to do with isolating the earth of the device from the electrical supply earth - I think it's acheived with a transformer. Ground lift is commonly seen on DI (Direct Injection) boxes to eliminate mains hum.

Mid scoop = smiley face eq curve. Basically, attenuating a big chunk of midrange.

Ground lift is to do with the DI output which is often used to connect amps to mixing desks. The earth lift disconnects the XLRs ground pin (pin 1) so that the amps signal ground is not directly connected to the mixing desks signal ground - this can help eliminate ground loops (which can cause audible hum.)

It does not compromise the "safety" ground (or mains earth) and the amp remains referenced to ground at all times.

Transformers are not used in this context, but the balanced signal present at a DI output can be created by using a "balancing transformer."

nifty

front

It would seem a style of playing by some bass guitarists benefits by cutting out some of the mid-range frequencies. I've come across hum loops of course but am not familiar with the tems used in relation to DI boxes.

It's just the same as any other ground loop situation. Two devices that share a common mains earth as well as having their signal grounds connected in some way can form a ground loop. So, the ground lift removes the signal ground connection. Worth mentioning that by doing this it also disables phantom power to the DI - which is not needed for DI outputs built into amplifiers any way.

nifty

used

I will add to my abbreviations etc file , this weekend

Ground lift removes an earth connection somewhere. If it's a passive pickup with an unbalanced output it would also remove the signal. ;-) It's of use where there are two earth paths causing a hum loop.

Mid scoop will alter the frequency response around the 'presence' frequencies - ie about 3-5 kHz, approx.