BM6500 / 7000 Powerlink – Attenuated Speaker or True Pre-Amp Out?

[machineage]

Hi all!

Can anyone tell me if the Powerlink audio outputs on the Beomaster 6500 & 7000 are attenuated speaker outputs, or are they true pre-amp outputs? Thanks!

[Guy]

Hi and welcome to Beoworld!

I had a look at the circuit diagram (available to paid members) and the Powerlink Outputs are taken from the pre-amp stage (after input select, vol/tone control and muting).  They do not go through the ‘Output Amplifier’ which supplies the speaker outputs.

Location: Warwickshire, UK

My B&O Icons:

[machineage]

Thanks!

I just found the schematic, and yes I see now, the pre-amp outputs are fed through 100Ω resistors to pins 3 & 5 of the Powerlink sockets.

[trackbeo]

Novice question for the electronic experts here: Why the 100Ω resistors?  Safety load to prevent shorting?  Impedance matching, i.e. a dup of some 100Ω later in the amp circuit?  IOW, what differentiates the amp next-door in the chassis from an amp down a few meters of cable inside the speakers?  When running line-level output around the room, why would one reduce the already-low output?  For that matter, I guess the same question is why you can’t hear the plugging-in of Powerlink speakers dropping the volume level to the main out speakers.  Basic I’m sure, and I heard “output impedance low –> input impedance high” for line-level amps, but don’t *truly* grok else I might understand the resistors…  TIA.

[Ninni]

It’s probably to prevent external loads from affecting normal operation of the internal power amp (and speakers connected to it).

[Author]

Posts