Subwoofer

[David A]

6. I tried the Devialet in a active way as a pre out: sub filtered at 12Hz 24/octave in combination with the Clearaudio turntable with TT arm and with the sub out (all settings tried). On paper this was beautifull: in practise the Rel way keeps the best way by far... The disappearing act is far away in this active way.

I don't understand what you mean by this or what the 'Rel way' is....

Are you saying?

1. Run the main speakers full range. Don't use a high pass filter.

2. Don't use a filter on the pre-out.  Use the low pass filter on the subwoofer.

As a counterpoint to what @Peter van der Laarse wrote:

My first REK was a Strata III back in the days when I was using a NAD M3 integrated. I never managed to get it to work convincingly with the speakers in my audio system. At that time I was just starting to get interested in home theatre and was setting up a separate system for my TV. I moved the REL to that system, used the line level connection to the sub out on the Denon AVR I was using there, ran the automated setup system, and got instant success. Years later, having reverted to stereo in the HT setup and gone back to a stereo amp there, I once again tried the speaker level setup but ignored most of the REL instructions, used pink noise and an octave band frequency analyser app on my iPhone, and finally managed to get good results, actually very good results, with the speaker level setup. As Peter said however, you need to set the crossover setting on the REL low (I set it as low as it would go" and I ended up setting the REL's gain setting much higher than I thought I should. I don't find the speaker level setup easy with RELs, especially when I'm trying to do it by ear. Having octave band sound analysis makes it a lot easier and gave me better results than I ever got trying to do it by ear.

Peter mentioned an Audioquest cable for the REL. REL make a better quality cable themselves and I found it gave better results than the cable that comes with the sub.

I never tried a stone slab of any sort under my RELs, partly because they were on ceramic tiled cement slab floor. I  had a problem with the sub moving over time, however, because the tiles had a slightly uneven surface and all 4 feet didn't contact the floor equally well. I ended up using Auralex SubDude bases, essentially an MDF platform on a heavy acoustic foam layer. That gave an even surface for the REL's feet and stopped the subs moving, and it delivered better sound as well.

In the end I think you can do equally well whether you use the speaker level connection and run the speakers full range or use a line level connection with the amp providing a crossover between speaker and sub. If you're using the speaker level connection set the sub's crossover setting as low as it will go. If you're using the line level connection and letting the amp do the crossover then set the sub's crossover setting as high as it will go because the amp is providing crossover control. Either way, however, you need to balance the sub's level against the speakers' level to get a successful result and I found I needed measurements to do that. The way which worked for me was using octave band analysis and pink noise and adjusting the sub's gain until I got the smoothest response I could over the range from around 100 Hz on down, even though the crossover was set below 50 Hz. The app I used also offered third octave band analysis. I thought that would be better because of the greater resolution but in fact it made things harder because room modes were easier to spot and produced taller spikes on the display and I could never get them as low as I wanted. Using octave bands resulted in a display with spikes which weren't as large because the energy was now being averaged over an octave rather than a third of an octave and that actually made it easier fro me to get a smoother looking result on the display. Measurements are tricky because show levels which don't look like the way we hear the sound. Basically using octave band analysis may be lower resolution than third octave band but it makes the job of balancing the level of the sub to the level of the speakers much easier.