1068 Bass Management

[mgrobins]

Hi,

first thread for me on this forum so go easy .

I have a 1068 pre-pro and have been trying to integrate a new sub into my system. The pre-pro is quite new and I haven't really made much effort to get to know it until now.

I'm trying to gain an understanding of how the advanced bass management works so I can get things set nicely. I'll include my text from Planet Audio (guys there recommended me to this forum - I didn't know there was a club Rotel :P).

My SVS PB12 arrived today and I decided to play around a bit with the bass management while I was setting it up. It sounds tremendous compared to my old ASW1000 and does much better in my large room. It's actually smaller than I thought it was going to be but it's a heavy sob tongue.gif

Now... about the settings....

I was measuring the freq rsponse using REQ wizard and decided to play around with the BM on my pre-pro.

Basically I need some help to decipher what some of the settings do. The manual is useless!

Bass management can be handled globally under the "sub-woofer" settings or for each speaker under the "speaker" menu advanced section.

Crossover can be set for each speaker -> front, center, surrounds.... but also sub-woofer.

Why on earth is there a crossover setting for the subwoofer? I initially set this at "off" and that seemed to feed the sub a full range signal then. I tried at the same freq I had my fronts set at (60Hz) and did a scan of 10Hz-200Hz using the sub & fronts. There was a huge null at the crossover freq.

I ended up setting the sub crossover at 80Hz and the speakers at 60Hz. I'm assuming this accounts for roll-off and allows a more even transition but I'm kinda stumped.

Basically i'm trying to figure out what the different settings/ crossovers achieve so I can work at integrating sub and speakers better.

My BFD arrives soon and I really want to get a better handle on the system settings before adding more complexity. Just changing the crossover points seems to add/remove peaks and nulls.

Hope someone can chime in with some good advice .

I'm assuming the "subwoofer" crossover in the advanced menu is a LPF for the sub and that the others are HPF settings for the satellites. I'm just not sure why a separate setting is included instead of things being managed for each speaker when the HPF is set (so maybe my assumption is wrong).

I tried e-mailing rotel support and was told that the setting changes the slope of the filter. I'm trying to clarify this with them as I thought that sounded a bit strange.

Hopefully someone can clear this up nicely!

[Kevin D]

They give two options for the mains and sub to help any dips or peaks in the room response. Since the points are not brick walls but gradual slopes, if you set the sub to 60 and the speakers to 80 you still get information 60-80 but less then if both were set to 80. If you set the speakers to 60 and the sub to 80, you get more signal 60-80 then setting both to the same.

Hope that helps,

Kevin D.

[mgrobins]

Thanks Kevin,

that's what I have been doing and it works well. Now that I know correctly what each setting is doing I can tinker with more confidence to get the best sound .

[Bostonears]

They give two options for the mains and sub to help any dips or peaks in the room response. Since the points are not brick walls but gradual slopes, if you set the sub to 60 and the speakers to 80 you still get information 60-80 but less then if both were set to 80. If you set the speakers to 60 and the sub to 80, you get more signal 60-80 then setting both to the same.

Kevin,
Thanks for a useful explanation. Do you know, if you set the center channel to 80, does the below 80 center info get redirected to the mains, or to the sub, or nowhere at all?

[Kevin D]

I'm pretty sure all others cut to the fronts and then the front setting determines where all of it goes.

Interesting side note, LFE is LFE and is not effected by the crossover. I think the specs go up to 200hz, so if there's 180hz info on the LFE track you will get it out the subwoofer jack.

Kevin D.

[focus]

I'm pretty sure all others cut to the fronts and then the front setting determines where all of it goes.

Interesting side note, LFE is LFE and is not effected by the crossover. I think the specs go up to 200hz, so if there's 180hz info on the LFE track you will get it out the subwoofer jack.

Kevin D.

well, if you're right i'm a happy man. But it doesn't seem to be the case. On my RSX 1067, the LFE track
seem to be effected by the sub crossover. Or am i wrong?

[Kevin D]

I haven't personally tested the 1067, but I have tested the 1098 which uses the same processing chips. Using an LFE only test tone on a DTS track with an RTA meter hooked to the sub output; the frequency range and amplitude was not effected by any crossover setting.

How are you coming to your conclusion? Unless you have a disc with a 5.1 track that ONLY has signal on the LFE signal, you're going to get a lot bass from the main channels mixed in (which are effected by the crossover).

Kevin D.

[focus]

I used The Calibrator DVD which makes it possible to run a sinus wave on choosen freq. I came to the conlusion when i played a 63 hz tone, and at the same time changed the sub crossover on the rotel RSX 1067 from 60 hz to 40 hz. The tone went from strong to weak. It was a DTS track and i have all my speakers set to small. Where do go wrong? I really want to sort this out!

Thank you

Fredrik

[Kevin D]

I'm not sure how 'The Calibrator DVD' has it setup, but when you select the frequency does sound come out of speakers other then the sub?

If you play a 63hz signal with your sub turned off and the speakers set to large, do you get sound out of front speakers? If so the test track has sound on channels other then LFE. These signals will be cut out by the crossover setting and sent on to the sub output in addition to the LFE signal.

I could never find a disc with a 5.1 track with varying test tones only in the .1 channel and had to make my own.

Kevin D.

[focus]

Ok, i will check again!

[focus]

I haven't checked yet, but this tread seem to be about the same issue: http://www.htguide.com/forum/showthr...=crossover+lfe