Pure Audio and sub

metalmackey · 4 Apr 2015 at 15:40

Hi experts

I have an Onkyo nr818 receiver and Monitor Audio rx6 speakers and a sub. When I listen to tunes I use pure audio mode which sounds awesome but switches off the sub. Is there a way to use the sub in pure audio mode for bass heavy stuff like The Prodigy?

Ta

lucid · 4 Apr 2015 at 17:33

If it's the RX W12 sub you have, then have you tried connecting the subs L & R to the 818 pre-out FL and FR (i.e not the SW connection to the subs R input), then setting the front speaker range to Full?

If you connect this way then you'll need to set the sub's own crossover properly, but just as a quick test you can skip that simply to find out if the sub stays active in Pure Audio mode.

metalmackey · 4 Apr 2015 at 18:49

Thanks Lucid. The sub is a BK Monolith+, used mainly for movies and games. Was wondering if it would sound better to have it used when playing me tunes. The bass from the RX6s in pure audio mode is actually good. The crossover is set at 80hz for all speakers, should I set the fronts a bit lower say at 60?

james.miller · 4 Apr 2015 at 18:57

Pure audio turns off all processing, including speaker size settings etc. Pre-outs to the sub as lucid suggested is the only way to get the sub working in pure audio Unless you're listening to audio with LFE content of course.

lucid · 4 Apr 2015 at 19:25

metalmackey said:
Thanks Lucid. The sub is a BK Monolith+,

Ah, there's your answer then.

Your sub has the circuitry needed to accommodate two simultaneous connections. This means you can connect the LFE as you have now, and at the same time the high level speaker connections.

What this means is that the 818 can be set to full range on the speaker outputs for front L&R, the sub will filter the sound coming in via speaker cables and allow you to use its phase, crossover and volume control to blend with the RX's. At the same time it will accept the LFE feed from the 818 where the receiver uses its own phase, crossover and volume control to set the blend with the rest of the speakers. In effect, it's like having large floor-standers up front on speaker wire plus a sub. The difference is though that the sub is doing the bass work instead of large fronts.

To make this work you'll need the neutrik cable that came with the sub. That connects in parallel with the front speaker wire connections. The user manual details how to connect.

When in Pure Audio mode the LFE signal will still go off, but that doesn't matter any longer. The speaker level output will still provide full range audio so the sub will do bass while the RX's do the upper frequencies down to where they naturally roll off.

metalmackey · 5 Apr 2015 at 13:50

Cheers Lucid, does it matter that I'm bi-amping my fronts?

lucid · 5 Apr 2015 at 14:13

The sub needs to be fed from the same outputs on the amp that are driving the woofers. Also, if you're using the amp's time alignment feature for tweeter/woofer timing then you'll need to spend a bit more time with the sub's phase control. Other than that, I can't think of any other issues right now.

james.miller · 5 Apr 2015 at 17:03

Yes, if you find you are swapping between audyssey on and pure audio (which switches audyssey off) then you'll run in to phase issues unless you set the phase knob on the sub correctly prior to running audyssey. If you don't do that then phase will be all over the place.