How to drive a passive subwoofer with a 7.1 receiver ?

You want to drive a passive subwoofer or amplify your Hi-Fi system with real Bi-amplification? Then this little trick will explain you how to do it with "Zone 2" option.

Most of 7.1 receivers have a Zone 2 option which enable them to work in 5.1 + 2.0 for another set of speakers located in another room (really ?)


We'll use that second embedded amplifier to power the bass !

I connected the LFE to DVD IN but any analog input should work.

My subwoofer uses two speakers so there is two ways to drive. You can easily solder a custom cable or buy one in your favourite online store :

Now we are ready to go ! Let's set up everything

I'm using another amp to drive my front speakers

Go in your receiver's menu :
For the main zone, make sure LFE is enabled and your speakers are set to small (setting your front speakers to large will automatically disable LFE when listening to music)

Switch on the "Zone 2" mode. Assign DVD IN (or the other input you plugged in) to Zone 2 and turn the volume up ( not too much ;-)

Here you go, you subwoofer is now powered by your receiver!

How to build a pre-out on Pioneer VSX-921

Yesterday I opened my brand new Pioneer VSX-921. The goal was to build a pre-out connector to connect a real amplifier : a Rotel RA-820A.

Rotel RA-820A taking care of the Front Channel over Pionner VSX-921

Let's look inside the beast :

• The green PCB is the Digital I/O board
• On the upper left corner, when can see the power supply.
• Of course the large radiator is covering the power amplifier board.
• The audio Signal processors and analog I/O are under the green PCB.

Let's find the pre-out signal !

We are looking for the pre-amp signal in order to extract it and feed a better amplifier. So we just have to find the wires between the DSP/Analog board and the amplifier...

Bingo ! Too bad we can't exactly see what's written ... But sure it's here !

Now let's find a convenient way to solder a bunch of RCA plugs... You will have to unscrew one support board and remove three plugs to access it ... no big deal!

Found it! A quick soldering and here we go, the left channel is available !

FYI : 

1 : Front Left

2 : Gnd

...

9 : Front Right

10 : Gnd

The two main channels are extracted, let's pu everything back in place and enjoy the cristal clear sound out of a real amplifier !

Here we go !




Next post will be a small but usefull tip how to use Pioneer's VSX-921 integrated amplifier to drive a passive subwoofer (or bi-amp).