Will I benefit from upgrading REL subwoofer pair

Hi Audiogoners,

I am only about 4 years into my quality audio journey. As a result, I bought elements of my set up at different times in the journey. Right now, I am using a Lumin T2 feeding a Hegel H390 amp which animate Focal Kanta 2 speakers. All cables upgraded. I also have duel REL Tx/7 subwoofers - which I thought were great until I upgraded my ethernet switch.

This small change lowered the noise floor in my largish (25' x 20') room and suddenly the subs started to sound a little flabby. So I upgraded their hi-level connection to the REL Bassline Blue cables. Much much better. 

But it led me to wonder if I should sell the duel Tx/7 subs and get a single REL S510 (and eventually 2 of the S510s). 

I *think* the speed of the Tx/7 s is sufficient but they may not be a match for the Kanta 2 speakers.... 

Does anyone have any experience with these components? Or advice?

Thanks Nadine


I currently have (2) S510s in a smaller room..I thought I was done for some time but I plan on moving to Perlisten...as good or better than Rel reference.Check them out but for sure the T series is not good enough for those Focals in my opinion.

Those are very small subs and your room is large.  I would go for the largest pair of RELs possible.  As you go up their line the drivers actually get faster.  Perlisten get great press.


Hi Nadine,

You have a complex problem. The largest component of the problem is a large squarish room. The speaker system and room have to be considered as one. Do you sit in a listening position and focus completely on the music or are you using it mostly for background while you do other things? 


A drivers "speed" is defined by it's frequency response and volume. Any two drivers of similar size playing the same frequency at the same volume are moving at the same average speed. Twice during a single cycle the driver is at a dead stop. "fast" is not a good way of describing a driver's performance. The terms "dynamic" and "detailed" are better. Muddy bass is usually not the fault of the driver. The three main protagonists are enclosure resonance, poor integration in terms of time alignment and phasing with the main speakers and finally room acoustics. 

I think there’s a couple of things going on, and none of it is cabling. More likely your flabbiness has to do with changing speaker locations or room acoustics/seating.

Two 7" drivers don’t have enough surface area to provide a lot of deep bass. Combined they offer about the same surface area as a single 10" driver. You would be much better off getting a single 12-15" subwoofer with proper EQ control.

Also, the room probably has some gnarly room modes. Use the AM Acoustics Room mode simulator to give yourself an idea. Try to keep all your speakers and your listening room out of the lowest modes.

Use measurements to see what remains. When you have that you should consider:

  1. Appropriate bass traps if the room modes are severe
  2. EQ to clip the biggest peaks (hopefully in the sub). If you have Roon, use built-in DSP for this.
  3. Plugging the ports in the Kantas to relieve them of the distortion in the lowest octaves and allowing a good sub to take over more. Some users have found that plugging only 1 gives them optimal in-room bass.
  4. High-pass your main speakers (in addition to the port plugging) if possible.

You might also want to look at this blog post. I don’t know if you need a sub or not but it may help you see how measurements can help you.



Why REL? Other subs have variable phase, which can prove critical to integration. 

Hey thanks to everyone for their comments and suggestions. @missioncoonery ​​​​@vonhelmholtz I will definitely look up the Perlisten. I agree that the T series is below the Focals... I bought the T series when I had the KLH Model 5s in a smaller room. 

Thanks also to @erik_squires. I think you nailed with with the comment about the 2 7" drivers. I do have Roon so will experiment with that. But I can also try plugging the Focal port(s). I had not thought of that...

@mijostyn I definitely only listen to music when I am listening. I do not enjoy "background" music. I am all there when listening. Since I upgraded the REL cables, the bass is more dynamic but perhaps I am looking for more detail. 

OP:  Strongly recommend you get some way to measure your system, OmniMic or Room EQ Wizard with a calibrated mic will put you years ahead in getting proper speaker to room and speaker to sub integration.

+1 @erik_squires on measuring. Indeed, it was by using measurement that I realized that the REL option of phase 0 or 180 was too crude. That's why I posted about variable phase above, and also about DSP. Physics always wins.

Yes for sure IMO. But first measure the room with something like REW (it is free, just need a mic). Secondly I would add a highpass filter first before changing subs. 99% of disconnect is frequency related.   

Thanks again to everyone who responded. Really appreciate @erik_squires and @hilde45 suggestion to measure. I know I must but for some reason, love to just move around the room and listen. The numbers hurt my ears :) 


Phase and time alignment are two separate issues. A sub can be in phase with the main speakers but two cycles late. The sub has to be in phase and on time. The only ways to adjust time are either by digitally delaying the "late" speaker or moving the speakers relative to each other. That can be 15 feet or more in some instances.


Good, you are a serious listener. I hate to waste a lot of hot air on someone who is not.  

The low pass filter that most subwoofers have is only good for mediocre performance at best. The same holds true for subwoofers that have passive radiators. Rel makes subwoofers that can be added to a system in the least expensive way possible. 

Part of the beauty of subwoofers is that they allow you to remove distortion creating bass from the main speakers. The result, besides cleaner sound, is better imaging. This requires a two way crossover that puts a high pass filter on your Focals. Unfortunately, you have traveled down a road with a dead end by getting an integrated amplifier that does not have an amplifier input. You can not use a crossover or processor with it. If you wanted to do this in economically acceptable steps. You need to get a stand alone amplifier. Hegel makes several of them. Your dealer may allow you to trade your integrated in. Along with the amp buy a MiniDSP SHD digital preamplifier. They are only $1300. The SHD will measure your system with a microphone, correct many problems and provide a full crossover for your subwoofers. Next and last would be to upgrade the subwoofers. Two 12 inch units by JL Audio or SVS will do. If you think cables make a difference, wait till you get a load of this!

If you decide to go this way and have any problems setting it up feel free to message me. 


@mijostyn For sure, I have made mistakes in my purchasing. I was so ignorant when I began and never imagined that my ears would become so critical. I have browsed the mini DSP site and believe that I can add a SHD studio to my system as I already have a DAC/streamer (Lumin T2) as well as the integrated amp. Am writing them a support ticket to inquire.

So to everyone who suggested that I start to measure @erik_squires ​​​​@hilde45 , I am convinced - if still reluctant. Going to order the mic to start.


@hilde45 asked.   Why REL? Other subs have variable phase, which can prove critical to integration. 



Do REL’s sound terrible if trying to integrate them like a normal subwoofer?  Meaning putting a digital high pass on the main speakers and a digital low pass on the rel using the low level or the LFE input on the back of the REL?