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

5 replies
machineage
Offline
machineage
Bronze
Posted April 1, 2024 at 06:57 GMT
#1643512
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
Online
Guy
GoldModerator
Posted April 1, 2024 at 10:52 GMT
#1663766
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:

BeoCenter-9500.png BeoCenter-9500.png
Beoremote-Beo4.png Beoremote-Beo4.png
Beovision-10.png Beovision-10.png
Beotime.png Beotime.png
Beosound.png Beosound.png
Beosound-Explore.png Beosound-Explore.png
Beosound-Essence.png Beosound-Essence.png
Beoplay-P2.png Beoplay-P2.png
Beoplay-M3.png Beoplay-M3.png
Beoplay-H4.png Beoplay-H4.png
Beoplay-H3.png Beoplay-H3.png
Beoplay-Form-2i.png Beoplay-Form-2i.png
Beoplay-Earset.png Beoplay-Earset.png
Beoplay-A2.png Beoplay-A2.png
machineage
Offline
machineage
Bronze
Posted April 1, 2024 at 23:58 GMT
#1663796
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
Offline
trackbeo
Bronze
Posted April 2, 2024 at 12:19 GMT
Edited April 2, 2024 at 12:40 GMT
#1663818
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
Offline
Ninni
Bronze
Posted April 2, 2024 at 15:51 GMT
Edited April 2, 2024 at 15:52 GMT
#1663827
It's probably to prevent external loads from affecting normal operation of the internal power amp (and speakers connected to it).
or
BeoWorld Gold Membership card
Join BeoWorld

Register to access the forums, reference material, and exclusive member benefits — including our monthly prize draw.

Become a Member

December 2026 Prize Draw

Gold Members Only

As a Gold member you're automatically entered into our exclusive prize draw — your chance to win iconic Bang & Olufsen products. A unique benefit of BeoWorld Gold membership, every draw brings a new opportunity to win something special.

View Prize Go For Gold