Adding an Sub that doesn't go well below speakers?

The backbone of my setup is based on a couple of Canor Monoblocks that feed a pair of Marten Oscar Trio. The trio are rated for 27hz (-3db), but I still feel that the system would benefit of having one or two subwoofers that help both of below 27 while also allowing more breathing space for the speakers.


I was considering a couple of REL T5X because of the little footprint as well as the high line connections (the amps don't have a dedicated low-level sub out). But just before pulling the trigger, I saw that the T5X is rated at 37hz (-6db). 

Would it make sense to add them to the system? Doesn't sound right. I know probably the Martens roll off above 27, but perhaps 37hz sub is too high for my system.

Perhaps a T9X that goes to the same 27hz? Or do I definitely need to splurge and do for an S series, like the S510 that is rated at 20 hz? If I do an S510 I will do just one and add a second once my wallet recovers.


Well, would love to hear from you. 



I agree 101%. The point isn't so much to lower the frequency response. It's to improve the overall low frequency response in your listening space.

Although the placement of your main speakers may be ideal for the highs and mids, chances are that the low frequency can benefit from the addition of a pair (or even better four) subs. And don't simply plunk a sub next to each of the mains. Any low frequency response problems will be linked to that spot in the room, so the subs should be placed where they perform best, instead of where they look good.

My KEF Reference 5’s supposedly go down to 25hz -6db with the short port tube inserted and I only have one sub about 6’ behind my listening position.  It’s really all I need.

All the best.

Hi ,

Best thing is to contact Rel and ask . I know a few people who have done this and had a great response .


Dialing in a room is tricky. Typically, multiple subs are helpful. In addition, having adjustable phase on those subs is helpful. I have both REL and Rythmik subs, but only Rythmik’s adjustable phase makes it possible to get the room dialed in. The last piece of the puzzle is DSP. I run all three subs through a miniDSP and that completes the integration. A response from 20-300 Hz within +/- 4db of flat. Bass is full and also articulate.

What’s great about the Rythmik phase control is that it allows one to position the sub where one wants it in the room (to avoid locations where room modes exist---peaks or nulls, a consequence of room dimensions); then, the phase control is used to align the sub with the main speakers. Many of use would not own a sub without a continuously-variable phase control. The 0/180 phase switch on many subs, including the REL, is far too crude to be of much value in a high performance system.

REL is clearly a good product and they have a very vocal and earnest fan base. As I said, I love my REL sub, but the ability to adjust phase in a variable way is an absolutely crucial feature for anyone without a dedicated listening room and the dozens of hours it takes to get a sub without variable phase placed. It is ridiculous for REL not to include this feature, but they don’t. Yes they have a "high level" way to connect to the amp, etc., but that’s not very important if they task is achieving a blend with both room and subs.

Roll the bottom out of the mains from at least 40Hz with a passive first order filter to the main amps

2x Martin Logan 800x or better. Any similarly capable sub with multiple XO slope, 180° continuous phase, polarity inversion.


miniDSP 2x4HD if using digital source or analog active XO. Note the analog inputs on the 2x4HD are not acceptable for HiFi. The advantage of digital XO is time delay. With analog XO, you have to shift the woofers about more for the best integration


NEVER EVER use the high level inputs on a subwoofer if you are serious about sonics.