Understanding how bass is redirected when setting crossovers

[cbelizon]

Hi all,

I have a really "simple" question about crossovers settings on a receiver (in my case it's a Denon x3800h) that I can not find answer to. So, when I a set a crossover let's say 60hz (my mains reach easily 25hz), all the frequencies between 25hz and 120hz (provided I left the LPF at 120hz as recommended everywhere) would be played on the main speakers, the question that I have is, would be only the frequencies that supposes to go to the L/R speakers or also de LFE? In case that are both, LFE is one channel, so, depending on the trims, the "sound level" of those frequencies that falls into the range or 60hz and 120hz are "distributed" equally between the sub and the L/R? Or the frequencies between 60hz and 120hz on the L/R speakers are played at the same sound level as the speakers is playing?

Le't assume the crossover is a brick and there is no slope, just for me to understand how is the LFE channel handled.

Also, in latest denon firmwares looks like LFE + main is pretty different than setting a set of speakers to large. LFE + main it's only used when you have set all your pair of speakers to small, and what it does is replicating the bass notes under the crossovers to the subwoofer. Whereas when you set a pair of speakers as large, then, the distribution option is enabled and you can set "how loud" the bass is going to be played within those pair of speakers set as full range. Is this level (that can be 0, positive or negative) applied per speaker? Is it based on the trim levels set on the levels of th speakers? Is it distributed evenly with the subwoofer level?

For example:

- I set the L/R to large, Surrounds to 100hz, LPF to 120hz, 1 subwoofer
- L/R trim levels to 0, Surrounds to +5, subwoofer -6db, and distribution to 0, how "loud" the LFE channel would be played on the L/R? At the same trim level set on the speakers levels? Or is it going to be split between the subwoofer and the LR evenly?

It is really not well described on denon's manual, and I'm struggling to understand it.

 

[voodooless]

Regarding the LFE channel, see here: https://manuals.denon.com/AVRX3800H/NA/EN/DRDZSYimemaleu.php

You can choose to distribute the LFE signal to almost any speakers you like and choose how loud that should be. The crossover set for that speaker still applies. Also, note that the subwoofer crossover for LFE can be different from that of the normal bass. So you can have the sub play bass from 80 Hz and below and have to play LFE up to 120 Hz. It's all in the manual, but in several places and not very conveniently explained.

 

[cbelizon]

Thanks, I read that, but still, struggling to understand how the distribution of bass "distributes" the bass, evenly? It just replicates it?


Also, regardless of the distribution or running full range or LFE + main, if I have different crossovers for pair of speakers, with different trim levels, how "the subwoofer" knows how loud to play the "bass", does the receiver calculates the different bass frequencies based on the trim levels?

 

[Beershaun]

You could try an experiment to see what is actually happening in your case. You could get a spl.meter app on your phone and put it at the listening position. Then stream a test tone to your AVR at a frequency below the crossover, at the crossover, and above the he crossover (60hz, 80hz, 120hz) and see what the measured SPL level is at the listening position. That won't tell you the LFE level is but will tell you if the AVR is keeping a consistent spl (to the target curve) with your speakers set to large or not. You normally get +3db for each speaker you add at the same volume if the AVR is not compensating for them.

 

[voodooless]

Thanks, I read that, but still, struggling to understand how the distribution of bass "distributes" the bass, evenly? It just replicates it?

I'm not surprised it's confusing. They should include a diagram showing how the routing, and filtering actually work with the various settings. Maybe somebody already made something like this? As for "just replicates".. well, almost. In the case of LFE over normal speakers:

- apply selected LFE gain for speaker
- apply Xover for speaker
- apply delay for speaker
- send to DAC

the order may vary (except for the last step ), but the result will be equivalent.