Some Denon amplifiers have Ferrite clamps between transformers/power supply board and pre/power-amp circuitry.
I always thought that most well designed amplifiers have efficient rejection and don't need anything like this?
I always thought that most well designed amplifiers have efficient rejection and don't need anything like this?
Noise travels both ways, from the AC line to the component, and from the component to the AC line. Hard to know which direction they're worried about, but in either case, the clamps are part of the "efficient rejection" you're referring to!
It is against RF/EMI (either coming from outside or generated inside or both) so necessary.
Electronic circuits have a hard time rejecting such signals. On top of that we like to bring such signals ourselves to our own environment and preferably close to our audio devices too. Some newer technologies make the devices emit such signals. All in all RF is an enemy to good audio.
Electronic circuits have a hard time rejecting such signals. On top of that we like to bring such signals ourselves to our own environment and preferably close to our audio devices too. Some newer technologies make the devices emit such signals. All in all RF is an enemy to good audio.
I buy the little ferrite clamp-ons in bulk and use them on anything with SS rectification and/or switching PS.
Dan
Dan
When you go to an EMC test session you usually take (or borrow from the testing company) a wide selection of ferrites, and if there are problems passing, start adding them to likely candidate wires. More a dark art than a science.
Here it may be more about preventing RF breakthrough from cellphones that is audible (not a concern of EMC testing, but important to the manufacturer's reputation!).
Here it may be more about preventing RF breakthrough from cellphones that is audible (not a concern of EMC testing, but important to the manufacturer's reputation!).
Looks like they are clamping the aux. supply lines. They must have some sensitive digital attenuator , firmware controlled IC's.
They should of had those supplies right on the control PCB's , instead of running all the way across the amps (inductors,speaker outs).
OS