Rhythmic F12SE setup using line in

Well, regardless of the online instructions it sounds like either your crossover is set too high or the volume is set too high, or both. So I’d first play with turning those two settings down first and see what that does, and then try altering the phase to see if that can improve things further. The other thought is that your sub is not placed optimally in your room that the prior room correction software was compensating for, so you may need to experiment with sub placement in addition to adjusting the sub’s controls. Here are two helpful links to address both issues I recently posted on another thread that may be helpful for you too…

First, if you haven’t already, use the “crawl method” to find the best location(s) for the sub(s) in your room for best bass…
https://www.audioholics.com/home-theater-connection/crawling-for-bass-subwoofer-placement

Then use this to fine tune your sub’s individual controls…
https://lifehacker.com/how-to-properly-set-your-subwoofers-volume-without-sh-1506136549

Using these techniques should give you a high degree of confidence that your subs are dialed in well. Hope this helps, and best of luck.

I believe that your Marantz along with the Audyssey was performing both low and high pass functions and some e.q. functions. If you are unable to incorporate the Audyssey into your current setup you no longer have any of their benifets I.e. clear. Concise, crisp bass. The only function of the three that you have left is the low pass filter on the Rythmik.

The muddy issue comes from setting the low pass filter too high. Since the KEF’s have a -6 db point at 30 Hz. Start by plugging any bass ports the KEF’s may have and then set the Rythmiks low pas filter at 30 Hz. You can then make small adjustments in the crossover point until you achieve the sound you like best.

If your preamp is a stand alone unit, you could purchase an outboard crossover such as a miniDSP, which I believe is compatible with Audyssey and very closely recreate the the same set-up you had with the Marantz.

Low, High, or Mid for your dampening? Also, are you engaging PEQ?

High dampening. There is not a PEQ unique knob. The nonLFE switch setting is 50Hz/24. My only other option is 80Hz/24. I believe the crossover max and rolloff. 

@audiorusty 

Interesting recommendation. The KEF’s do come with plugs for the rear ports. I will give that a try, while reducing the crossover. Had a similar recommendation from @soix Thanks!

I would suggest doing one thing at a time.  Sometimes adding port plugs can change the sound characteristics of the speakers, so I’d definitely try that last after everything else is dialed in. 

Out of curiosity are you experiencing any differences when making a change to the settings?

I have two Rythmiks of this make. I have done a lot of work to dial in my subs (I have a third REL). Ultimately, the best thing to do was buy a mini DSP and integrate subs that way. Highly recommended.

https://www.minidsp.com/applications/digital-crossovers/194-subwoofer-integration-with-minidsp

I would prefer to dial in my sub without the use of the minidsp. They appear to work via ADC then back to DAC to do the sound processing, something I avoided  (NAD, Anthem, Lyngdorf etc) when purchasing my preamp. Help me if I am wrong. If I was to go that route, it looks like the minDSP FLEX is the one I should choose. Thanks!

I would prefer to dial in my sub without the use of the minidsp. 

I totally sympathize and tried for a very long time -- arduous, even onerous work -- to measure, move, listen, dial in and out, etc. to get the bass right. A good friend of mine who's been an audiophile for 30 years with an incredible and well-designed system (he also builds audio) has DSP for bass. It really does not "pollute" the sound in the way that many worry about for the higher registers. Keep in mind, this is limited to the subs only.

In other words, the benefit gained by dialing in subs (and room) far outweighs the (actually small) detriments of adding dsp to the system. For me, this was evident enough to help me reconsider and reject my bias against dsp.

Ok, so I better understand, I would run my sub line out from my preamp to the miniDSP, let it do its thing, and run that to the sub. My R11’s would still run full range analog directly from the preamp. The sound processing for the sub only would be based upon room characteristics & R11 output. Is that correct?

Placement of speakers and sub, not to mention chair placement, can have everything to do with clarifying  the low end, and everything else.  Maybe you have limited options to do this?

I concur with @audiorusty.   When I had my F12s in my system, I found the sound better when I plugged the ports on my speakers, moved the speakers away from the wall, turned up the gain on the sub and turned down the cross over on the sub.  

Ok, so I better understand, I would run my sub line out from my preamp to the miniDSP, let it do its thing, and run that to the sub. My R11’s would still run full range analog directly from the preamp. The sound processing for the sub only would be based upon room characteristics & R11 output. Is that correct?

You’ve got it exactly. The diagram below could have an additional sub added and with the other miniDSP model you were indicating, perhaps more. But you have the general principle exactly right.

OK, on the bass management, I thought I would provide status. I adjusted the subwoofer, the best I could with my ears. Did not sound great, so I decided to run Audyssey MultEQ-x from my Marantz AVR running home theater pass thru my Rogue preamp, both with and without my Rhythmic. I then was able to see the problem on the frequency response graphs... something between my R11's and my room was causing 32hz peaks of +16db followed by crashes of -12db at both 50 & 90hz, something I could never adjust out.

Several of you suggested port plugs, so thought I would try that... voila... the problem for the most part went away with full plugs on the right speaker (nearest the corner) and partial plugs on the left (mid wall). I was able to then integrate my Rhythmic back in adjusting for the flattest response measured by MultEQ-x... not perfect but very good!

I may at some future date buy a miniDSP, but right now I am happy and I remain hesitant with it's ADA conversions, as I believe to do properly, i would need to set both low pass and high pass digitizing my entire range.

Thank you to everyone for your excellent recommendations! Happy New Year.