Ground referenced Power Amplifiers

[tdelahanty]

Balanced designs are not centered about ground, ground is not in the equation. Both sides or halves are completely isolated from ground. To measure the output voltage you need a battery powered or isolated ac volt meter, it would be connected across the red and black binding posts. Do not connect a meter or scope from one binding post to ground.

[AudioGremlin]

Yes, my bad. Of course you're right I was confusing balanced with differential designs. The fact remains that I mustn't connect a balanced or bridged amplifier output to my active crossover & bass servo unit.

[AudioGremlin]

rayooo, will look into the Parasound JC-1. Theres a Parasound UK distributor but their website doesn't mention the JC-1. Worth a quick phone call to them. Thanks for your help.

[tdelahanty]

Originally Posted by AudioGremlin

Yes, my bad. Of course you're right I was confusing balanced with differential designs. The fact remains that I mustn't connect a balanced or bridged amplifier output to my active crossover & bass servo unit.

There is a way to connect them safely. I went thru this with balanced Krell and Levinson amps and a REL Sub. I'm assuming you are using a speaker level connection. Connect the R&L hot leads from the sub to the red R&L speaker posts of the amp and connect the ground wire to the outside (ground) of one of the amp's RCA inputs. This also assumes the RCA inputs of the amp are isolated from the chassis.

[AudioGremlin]

Thanks for that inspired workaround to float the ground. I'll be connecting the amplifiers output to an Infinity RS1b bass servo and crossover unit. I've heard other RS1B'S where they've swapped the bass servo & crossover unit completely for another manufacturers crossover thereby being free to use balanced amplifiers. Imo the lack of the bass servo in is apparent. I wish Bryston did a more powerful version of the 4bsst2 (the Infinity bass towers are hungry for current). I like Bryston for their 20 years warranty and build & burn in procedures. Some Classe models are suitable but some doubts are now creeping in regarding their long-term reliability and bass performance.