Help, please! Can't get any bass out of subwoofer connected to AV2. Why?

I haven't used an AV2 for some years but, as I remember it, the AV2 automatically selects the "correct" setting when the source is connected via optical cable.
Again, I think manual selection only works when connecting using the analogue inputs.

As you mentioned the coaxial cable, I imagine that's how you're connecting your sub.

With the speakers set to "large", I think that effectively alters the crossover points and how much bass is sent to the sub.
I'd try it setting the speakers to "small" and see if that makes any difference. Just be careful with the main volume in case you suddenly get earthquake effects!

Does the sub have its own independent volume control - like the Naim n-Sub for example.

Lastly, maybe try using a different method connection to check that the sub is actually working.
You might even cautiously connect a phono cable and just touch the end to see if you get a loud hum.

Hi Blythe, Thank you for your help.

I am using a coax cable to the JMLab SW900 sub which does have its own volume and other controls that I am quite familiar with, and both it and the coax cable works fine.

But I am doing SOMETHING wrong in the AV2 settings....as ZILCH bass is currently coming through to the subwoofer.

I have read in the manual that if the speakers are set to SMALL, more bass will be sent through to the subwoofer.

But I don't want to use the sub ALL the time, as for normal use (for example watching Eggheads!) I don't need the sub turned on.

When something mediocre comes along, like a 9pm thriller, I don't  want my mid sized, fairly bass-capable speakers to have their bass curtailed by the AV2 because I have set them as 'SMALL' . I want them to be receiving full-range, so I thought that keeping the speakers set up as 'LRG' (large) was the best way to go about this.

I just want to be able to switch the sub on occasionally, when I want it for EXTRA 'oomph' during big movies.

Any further thoughts would be most welcome, please!

David, IIRC the single RCA sub out is dedicated to the .1 channel of either 5.1 or 7.1 source material. 

Thanks Richard.

So if the AV2 is receiving, from my TV, an optically fed digital audio signal through Opt1, and I have the AV2 set on Dolby PLII (thereby being a 5.1 setup), the Sub set to 'YES', and all speakers set to 'Large', am I right to expect that on some kinds of TV program material, low bass will be sorted by the AV2 to go to the subwoofer?  Because currently I'm getting nothing through to the subwoofer at all, and I've tested both the subwoofer and its coax cable....

Or is this only going to happen when there are LFE effects in films from my BluRay player, unless I now set my speakers to 'SMALL'?

Many, many thanks for putting up with all these Q's!!!

Is your TV down-mixing the signal to stereo or some such that has no subwoofer output? I'd check what your TV settings are doing. For example we have ours set to PCM stereo because that's all our SN will understand.

Thanks, Winky. No it wasn't that. I've finally got bass out of the sub by changing the speaker settings to 'Small'. Unfortunately that has meant that they don't go full range. So it looks like with the AV2, it's an either/or situation. I can have bass through the speakers OR the sub, but not through both. I'm a little disappointed about that. Do you think that's how it should be?

I think your problem here is that you are trying to use the .1 LFE output for all purposes.  What you want to do requires a high level connection as well - I assume your sub allows you to connect this way as well and you can switch between the two. Or alternatively a pre-out level connection (IIRC the AV2 does have this on one of the DINs). The Naim n-Sub allows this and can be automated too.

Ah...so the coax sub out socket is for LFE only? Please could you confirm that, Richard, as that would explain it. Cheers, David

I'm pretty sure that's right but probably would need it confirmed by Naim.  It has been a while since I ran my AV2.

A quick and easy test would be to use a known source material, such as a DVD or BluRay, with LOADS of explosions etc. and see if the LFE does actually come through the sub...

I have actually now re-set my speakers as 'SMALL', and the crossover point to the lowest of 50Hz. By setting the speakers to SMALL, the sub now receives some low frequency signals from the AV2, and all is good. My previous AV amp (a Panasonic one) DID send LFE and low frequencies to the sub, whatever the speakers were set as (LGE or SML). So it was slightly different, and these settings are not really very explicit in the AV2 manual.

Anyway, I think things are sorted now.

Many thanks Richard, Blythe and Winkyincanada for all your suggestions, which have led to success.

Cheers, David

I think with any AV processor if manufacturers follow the THX standard (which majority of them do) bass processing is implemented as-

If you speakers are set to 'Large' then all bass is sent to your speakers and only the dedicated '0.1' bass is sent to the subwoofer. The '0.1' low frequency channel goes up to 120Hz, so if a effect is created in that channel then the sub will do it's thing. Other than that it will do nothing. 

As the subwoofer is designed to reproduce bass it is best to let the subwoofer do so (it makes sense!). Even though your speakers may look large they will not be able to reproduce clean and high dB bass at these low levels. That is why the THX standard states set your speakers to small and cut off at 80Hz which will send the bass region 80Hz and below to your subwoofer. In this way all bass below 80Hz is directed to subwoofer as well as the dedicated '0.1' channel bass.

You can test this yourself make sure you find some content which just uses the '0.1' channel, you will find no bass is going through your main speakers once they are set to 'Large'. Sometimes the director intentionally sends bass to subwoofer and main speakers, this is the disc you don't want to do this test.

Hope this helps.  

curio posted:

I think with any AV processor if manufacturers follow the THX standard (which majority of them do) bass processing is implemented as-

If you speakers are set to 'Large' then all bass is sent to your speakers and only the dedicated '0.1' bass is sent to the subwoofer. The '0.1' low frequency channel goes up to 120Hz, so if a effect is created in that channel then the sub will do it's thing. Other than that it will do nothing. 

As the subwoofer is designed to reproduce bass it is best to let the subwoofer do so (it makes sense!). Even though your speakers may look large they will not be able to reproduce clean and high dB bass at these low levels. That is why the THX standard states set your speakers to small and cut off at 80Hz which will send the bass region 80Hz and below to your subwoofer. In this way all bass below 80Hz is directed to subwoofer as well as the dedicated '0.1' channel bass.

You can test this yourself make sure you find some content which just uses the '0.1' channel, you will find no bass is going through your main speakers once they are set to 'Large'. Sometimes the director intentionally sends bass to subwoofer and main speakers, this is the disc you don't want to do this test.

Hope this helps.  

Thanks for your comments, Curio, I think you are right on the ball there. That CERTAINLY seems to reflect the way that I have ended up setting up my AV2/NAP175/NAP150X with my Philips ribbon speakers and my Focal subwoofer. It works a treat. Regards, David