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

First off, I'd love to hear that kit in person. Regarding the REL's, I believe those Marten's would require the speed of the S series in order to fully disappear in the mix. As an added benefit they go deeper. If you spoke with REL, which is easy to do, I'm sure they'd make the same recommendation.

@12many

How do you do this?

Without instrumentation, the best program is something that has a lot of air, significant low end and plenty of mids.

Being of Scots heritage, I naturally had well recorded Pipe and Drum bands. It’s the best program ever for dialing in subs. When you get it right, the focus snaps in!

Bach’s Toccata and Fugue in D minor recorded in a great space is also a favorite.

See ieLogical Subterranean Homesick Blues Setup

@javipi   I would check out the Rythmik subs as well.  If I recall, they go lower then the REL (double check) and have servo feedback.  

Amazing guys! This has been very helpful, despite some somewhat contradictory opinions. In any case, I will proceed with the S510 and try my best to dial in using REW and my poor ears. 

@12many Before I had DSP, I would turn the knob and then run a new REW scan and see whether it helped. 

@hilde45   "then, the phase control is used to align the sub with the main speakers."

How do you do this?  Are you using your ears or a mic and software?   I don't think my ears can pick it up phase difference between a main speaker and a sub (let alone two subs).  Sometimes I feel like a fat guy that can't cook. 

I can tell you from my experience with REL subs.  I first considered both the T5X and the T9X but finally settled on the S510 with the thought of doing the same and getting a second one when my wallet recovered, the only problem with that is the recovery is still on going so I still have only the one.  I can tell you for certain that I am glad I went with the S510, it add enough to the low end that sometimes I don't feel the need for another one that I would have to find room for.  Oh well, maybe some day.

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.

OR

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.

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.

https://www.rythmikaudio.com/images/PEQ_controls.jpg

Hi ,

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

cheers

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.

@hilde45 

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.

The biggest problem is the best position for main speakers is often the worst position for bass. You may not be getting the bass your speakers are capable of when in the best location for other sonic aspects. Subs allow you to position your speakers in their best position and put the subs where they work best. Using the small sub you are considering in the correct location will probably make an instantly noticeable improvement in your reproduction.

Plus if your subs have a high pass function(not all do) they will significantly reduce the load on your main speakers and improve the upper bass and lower mid-range.

Marten speakers, nice. 

When any speaker system is positioned in the middle of the room for presentation and sound stage, that room position is usually in the rooms null, choking the speakers potential low frequency output.

Shop for an actual subwoofer that's -3dB at their claimed low frequency output equipped with speaker level inputs and offers some modicum of equalization, or consider DSpeaker or MiniDSP.  

Locate it in your rooms loudest bass mode.   

You would need something like a S510 or better yet S812's to blend with those speakers. I'm using S812's with my Zu Audio Omen Def Supreme, but used them before that with Wilson Watt Puppy 8's. They definitely add a lot of dimensionality to the soundstage as well as adding to the musical foundation.

It does not make sense. 

Well, you won’t like what I have to say, but it’s based on repeated experience and measurements.

First, never take a speaker’s -3db point as any indicator of anything that’s happening in your room. The room will make the bass specs utterly useless in understanding what is actually happening. I’m attaching a link that goes over specific examples. Before picking a strategy you should measure what's happening in your room.

Second, the idea of keeping your main speakers going as low as possible because well, you paid so much money for them, is like buying a meal and only eating one half of it. Case after case where audiophiles changed their mind and tried raising the crossover frequency was a huge net positive, but no one likes to hear that their approach isn’t actually going to be optimal. 😪

Also take a look at the AM Acoustics Room Mode simulator and try to keep any speaker and listening location out of the worst/lowest modes.

Out of respect for my own sanity and the OP this is all I’ll say here.

https://speakermakersjourney.blogspot.com/2021/12/room-speakers-eq.html

In my experience, the subs help with the low end but also help deal with room modes -- they even out the bass, from 20-300 hz. Measurement and DSP are the best ways to add a sub. Of course, you want to get the right sub, so your attention to your speakers' capabilities is right on target.

@javipi , No, no the way you are planning on adding it to your system. First off, frequency response measurements are taken at one meter. That is a far cry from 4 meters. Most speakers do not put any significant power out below 50 hz.

If you were planning on using a complete, two way crossover, crossing up above 80 Hz you would get the benefit of decreasing distortion and increasing headroom even if you did not lower your bass. 

IMHO the low pass filters used in the majority of subwoofers is a bad joke. They do not high pass the main speakers and give you no control over slope and time alignment, two functions that are vital for proper integration. Other than having deep bass you should never be able to hear a subwoofer even crossing up at 120 Hz. Digital bass management is the superior way of doing thi Everything else is a compromise one way or the other.

"Would it make sense to add them to the system?"

NO!