Can anyone hear the difference when you add REL subwoofers when playing two channel

I would try with a broad range of music, just to be sure. Also, RELs in that price range don't hit down to 20Hz (T/9i) drops off at 28Hz - that could be the reason why not hearing much difference - although, like I said - could be choice of demo material, too. Try different styles of music.
I think you have to go to the S5 to get down to 20Hz or even the next model up from that. talking big $ if you want the REL to plumb the depths

I have a pair of VA Mozart Grands I picked up cheap when Best Buy dropped the line a few years ago.  In my experience if you want punchy, powerful sounding bass you need bigger woofers than the Mozarts have.  They play plenty deep but I find them to be distinctively lacking in punch and impact.  A subwoofer won't fix this because subs don't play the upper bass where the visceral impact comes from.  I believe REL subs tend to use smaller woofers as well.  I suspect this helps them blend with main speakers more easily but it also means they will have less transient impact than a larger driver.  

Why would the number of channels of a Music Reproduction System to which a woofer(s) is connected have any bearing, influence, or relationship to it's performance in the low frequencies. 

I wonder how many prefer REL subwoofers over other brands and if they can really hear the difference.  I talked to JL and they set up their subs to change the cross overs to produce the bass and allow the towers to provide more of the mid and high frequencies.  I also talked to SVS and I don't consider them to be of audiophile quality.  I was told REL designed their subwoofers to allow speakers to enhance what is already there.  I would like to the lower bass extension when listening to Michael Wollney's song, Little Person.  Songs with extended bass lines would be nicer to listen to.  

A lot of the guys who have only tried one or two subs in a system will tell you the REL is really good.

All of the guys who have tried a Swarm type distributed bass array with 4 subs will tell you this is definitely the way to go.

Because: it is definitely the way to go.

Sub or no sub makes no difference at all unless the recording has low enough bass to matter in the first place.

When you do get a Swarm type distributed bass array that will allow you to experience for the first time really low, articulate and dynamic bass, one thing you will notice is its hardly ever there, and then will surprise you when it is. Like a lot of times a bass player as he slides off a note it trails off and down, way down, way further than you ever heard, in fact you don't hear it you just sort of feel it. "Sort of" because it feels so much different than anything you're used to unless and until you've heard proper DBA bass. Because this just never happens with only one or two subs. Not unless maybe equalized, and then only in the one spot it was equalized for.

The best demo track I know, with powerful extreme low bass that is also musical and with a bass line progression making it easy to follow is Bela Fleck Flight of the Cosmic Hippo.

You're welcome.

might want to consider a Rythmik F18 then (better safe than sorry :) ):
http://www.rythmikaudio.com/F18.html

significant difference for me with a single REL S/5 SHO...and my speakers go significantly deeper than the Mozarts

S5 provides the Juice!

I added a pair of REL S/5s to my system, which has Focal Kanta No 2s driven by a Levinson 585.  Surprisingly big difference.  Not just the bass (although it was markedly deeper and more impactful), but also in the sense of air and space around the performers.  Worth every penny.

I am using a pair of REL Carbon Serie S (same Power as S/5) and they added another dimension to overall musicality. I picked out REL for bass quality and their seamless integration with the main speakers.  

To my ears, what makes REL performance extraordinaire is its clarity and focus in addition to its obvious bass extension and dynamic headroom. 

I would like to point out, subwoofer takes bit of patience and tweaking with placement. Once you get them dialed in properly, you wouldn’t imagine listening to your system without the subs ever again. 

What concerns me is how little watts the REL subs put out.  The T/9i with only 300 class A watts, the S3 with only 400 watts class D and the S5 with just 550 watts class D.  Other sealed subs in the same or lower price range put out 800 watts to 1500 watts.

larry,

What are your room dimensions? Don’t be alarmed by low watts. The idea behind employing sub in a two channel setup is to strike weighted balance and full-range musicality not earth shattering bass as in typical home theater setup. 

And they are not sealed, they have downward passive radiators 

I've always read that when a sub is properly dialed in, you should not notice it, but when it is shut off, the difference is quite noticeable...many say it takes a few days of listening before you realize the difference the REL is making, not just in deep bass, but in overall sound...

Kind of agree with the dealer, but it also sounds like the subs aren’t well integrated. I mean, no, you should not be getting chest thumps, but well done, subs are GLORIOUS!! The effects he feels you should be getting you aren’t.

If you can’t hear a difference, it’s not worth money to you, then don’t buy it. :)
To integrate a sub well into most spaces you need a pair of bass traps and DSP EQ.

Without this, you are forced to cut corners, and often that means leaving the sub at too low a level to really do it’s thing. Turn it up, and the room modes wake up and destroy the sound.

The thing JL does better than almost any sub maker is the DSP/ room correction. This lets them contribute more, and go deeper.  Often a "Musical" sub means it can't go deep, so the dragons stay slumbering.

As jl above points out a simple way to hear what a subwoofer is doing is to simply turn it off.  

The REL method of speaker or high level connectivity was a solution to connect to receivers back in the day that lacked pre outputs. The assumption is using the same signal the speaker gets exceptional integration is guaranteed.   

REL describes their product as providing bass extension and is not a subwoofer. In my experience their products ability to integrate and their bass performance is mediocre. Regardless of my opinion, if its connectivity and presentation appeals to you that's all that should matter.

Higher end subwoofers such as JL Audio F series and Velodyne DD Plus offer automatic equalization, room optimization, higher quality enclosures, drivers, and methods of speaker cone control. While these companies make a handsome product the majority of their extra cost is internal, design, and development. They will integrate with any speaker and last through system changes for years to come. If there's punch on the recording they'll punch and the only thing that will get spoiled is you.         

I had a Rel Storm 3 in my system for many years. I now have 2 Sumiko S-10 (Rel S5 clone). Fantastic subs and add much more than just bass as mmeeks & others have said. Earlier Rels had even  lower power amps. The Storm 3 only had 150 watts. It still made a large difference. in my >5000 cu ft  room. The Sumiko's have 550 watts and I only have them set at 1/4 volume. I' like  the Sumiko subs They integrate very well and  make the speakers sound much bigger (Silverline Sonata) They have the same specs as the S5 Rel and have the same nutrick high level connectors. Only difference I could see between the Rel & Sumiko is the driver cone material. Sumiko was the Rel distributor for many years. They no longer are Rel distributors nor do the make subs anymore.

I have owned subwoofers from REL, JL Audio ,Monitor Audio 
and SVS , without question or even a second thought the Brand New SVS SB 3000, or ported is by far the best subwoofer under 
$1500 Period the sealed model for $1k delivered with a 45 day
audition ,they even pay the return if not happy. It is fantastic and has a great  app . For phone or tablet.
to control it and a bunch of adjustment parameters on the app
to go down to a solid 18 hz . I bought one thinking on getting another tuneful Powerfull Bass ,this sounds closer to their incredible SB16, this has a 13 inch driver ,a Solid 800watts 
with 2500 watt peaks ,and the most powerfull processor ever 
in a Sub, from Analog Devises. Just check it out .

I couldn’t do without my REL....it adds dimensionality, air, presence and texture!

I added a t9i to my modified khorn set up and it works great . I like how it hooks up to the speaker outputs this seems to keep it life like and blends in great with the main speakers. Rel makes larger subs as well if you want more power.

ditto what dave said

To the OP, I thought the same exact thing when I demoed REL! For the life of me I couldn't hear a difference.. In fact, since the salesman insisted he could hear the difference, I took control of the subwoofer power switch and told him to tell me when it was on or off... And he got it wrong!  I do believe it can provide space, but I think it needs to be with the right speakers. Perhaps the speakers I was listening to were just phenomenal to begin with and covred that range. 

I am in the market for a woofer stereo pair. Right now I'm leaning toward Rhythmic F12s. SVS SB4000 also intrigues me.  The problem I have right now is spouse acceptance factor. I need to run cable to the woofers, but my amp is on a big mantle above the fireplace. That means the cables will have to come off the mantle at some point to connect to the amp, and will be an eyesore to the wife.  

I've looked into wireless options (i.e. rel longbow) but have heard there can be significant delay with some wireless systems.  Not sure what to do. 

I have 2  Sumiko S.9 subs which share the same technology as the Rel Ti9. Sumiko owns Rel & they're remarkably similar in design, specs & sound.  Paired with my Maggie 1.7i, one unit made a big improvement. Adding a second unit was markedly better. I have both subs on a wall switched outlet, so I can turn them on & off simultaneously to instantly compare the Maggies with & without the extended low end. The difference is huge.  The name escapes me now but I bought them from a retailer advertising the Sumikos for sale here on audiogon. I pushed hard & was able to get them fir $650 each shipped. I think the dealer is in Michigan. I'll try to find the paperwork & post their name. I got them about 3 months ago.

The Sumiko dealer I mentioned before is Paragon Sight & Sound. Sumiko isn't making subs any longer so the prices were low due to them being discontinued. I believe the Sumiko designed subs are now being made by Sonus Faber with a big price increase.  

In my experience having dual subwoofers (left/right channel) has made significant impact on the sound in terms of bass extension, depth of soundstage, air between instruments, etc.  Having said that, it does take some time to get it right.  Things such as placement in the room with respect to your main speakers, phase, low-pass filter, and volume settings all factor in so they blend in nicely with your main speakers.  When all is said and done, you really shouldn’t know the subwoofers are there, beyond the apparent soundstage enhancements.  Before you even start configuring subwoofers in your setup, make sure you have optimal speaker alignment first as well as seating position (should be where you have smoothest/even bass response.  I don’t have the fancy RELs, but own a pair of Definitive Technology Supercube I subwoofers.  Bass response is 13-200Hz and clock in at 1500W (more power than I need).  I’m always a little skeptical about in-store demos as things are probably not fully optimized.  From my perspective, it’s all worth the journey for getting better sound.
Gorm 

I have 2 rel. this is how you set up high level input:
make sure the yellow and the red are twisted together and going into the positive left on your amp and the black into negative left, and do the same on the right outputs. Put the crossover about sixteen clicks and the low level at about 10 clicks from zero. Play a track w repeating bass line. Lorde “tennis court” is a good one.Tune one sub at a time with the other sub off. First flip the phase button and whichever way sounds louder is probably the in phase for your setup. Work the crossover back toward zero until you like what you here. Work the bass level back to zero until the bass level matches the speakers but just kinda extends the bass response. Do the same on the other sub.  You’ll have bass that is on stereo and match’s and extends your speakers. Look for better soundstage and clearly better bass and midrange. Listen to sympathy for the devil, listen to the bass guitar, you can hear the guitar 🎸 not just the beat but the actual instrument, you can almost picture the strings being plucked. You can mentally picture where in the stage the bass player ( Bill Wyman?) is standing. Now your all set.

You can also run LFE input on the rel in conjunction w high level. If you have a surround processor w lfe out, this will go into the rel and should only come on with movies that have an lfe track.

MAKE SURE that your not running high level out into the REL and LFE out into the REL HIGH LEVEL INPUT at the same time. The sub out or lfe out on your amp needs to be input on the rel lfe input, not high level or you’d be defeating the purpose of true stereo bass extension. 

I hope this helps 
-ak

@larry5729  I'm not going to bother going to the REL site to check but I would be highly surprised (to put it mildly) if the T9/i puts out 300 "class A" watts.  

See my post which is directly related:
https://forum.audiogon.com/discussions/kal-on-sub-integration-and-antimode

Audioman58:
Doesn't the SVS turn the towers in to boom boxes and throbbing bass?  Did you have the same problem I am having hearing difference when you add and subtract a REL subwoofers when 2 channel listening?  The dealer told me I am listening for the wrong thing, an added bass sound.

When I listened to the S3, I got on my knees and put my ear next to the speaker and it was not pulsing out the beat.  All it was doing was putting a steady humming sound.  Hard to describe.

I believe it will only Throb with bass if the REL's low pass filter is "listening" for such frequencies. If the REL is set at 30Hz, but the Throb frequency is happenging at 40Hz, then the REL won't play it. That hum may well be the reverb/transient information and could be normal. Play music that for sure thumps at 28Hz then check again. Probably wouldn't want to get your ear right up to it. 

I have 2 "older" UK made RELs, a 10" Q108MKII at 100 watts, and a Q150e at 150 watts, and they integrate into my listening room extremely well...you do have to pay attention to level, crossover points, phase, and location, but even without a "room correction" gizmo they sound fabulous, and I don't miss a 20hz anything. I did drag my 92lb Mackie HRS (designed for recording rigs and not necessarily pro audio live work, although I have used it for a pro gig...once...) sub in from my recording room when I first bought the thing, and although it's a 19hz capable 500 a/b watts monster,  it didn't seem to add anything that I wasn't getting from my RELs. Sounded fine, but I guess I don't listen to pipe organs much. 

You should buy a track of just the 1812 Cannon and put on repeat

When I listened to the S3, I got on my knees and put my ear next to the speaker and it was not pulsing out the beat. All it was doing was putting a steady humming sound. Hard to describe.

Something is wrong with the setup. The steady hum could be a grounding issue. Sounds like your dealer doesn't know what he is doing.

Are you going to be using this sub in a large or small room?

If you want deeper bass, RELs are a poor choice. Without getting into the insanely expensive, Rythmik, HSU, PowerSoundAudio, and SVS give good/excellent musical performance and dig much deeper than REL.

“If you want deeper bass, RELs are a poor choice.”

@mzkmxcv,

It’s not all about deeper bass in a two channel audio, does any of these rings a bell....dimensionality, air, presence and texture. 

Which REL sub have you tried in your system to form such poor opinion? If you did try one, how did you connect the sub?

"I also question why REL manufactures their subs with such low wattage? For example, their S3 delivers only 400 watts and their T/9i's deliver just 300 watts. When comparing them to subwoofers like JL, which deliver 750 watts to $1500 watts, maybe REL subwoofers are just too wimpy.,

Power is not what makes deep, convincing bass. A combination of construction and location do more than the gimmick of massive wattage specs.
 
Have you ever heard a quality 5 watt tube system at full steam? Close enough to concert level for most ears.

If you're not hearing the difference when the sub(s) are off, then they calibrated incorrectly. The overall sound quality would be immediately noticed, when turned off. 

IMO, even the finest speakers in a great room, will SUBJECTIVELY sound more convincing with properly adjusted subwoofers.

Most people have no idea how powerful 100 watts actually can be, and the 1000 watt or so subs that are around generally use a class d amp to get to that level and only a fraction of that power gets seen by the driver, so it's seemingly a marketing thing as the overall design is what counts more than the horsepower. Stick an Ampeg SVT bass amp (300 tube driven watts into 4 or 8 10" drivers) in a room with the loudest home audio rig you can find, and that bass amp will embarrass the home audio system all day because it actually can use all the power from an uncompressed signal. At full steam you'd have to leave the room. There is no non-pro speaker that wouldn't instantly blow from 1000 actual watts. Highly efficient speakers make low watt amps work beautifully (at least with well designed amps), and a 100 or so watt well designed sub will mate beautifully if set up properly.

One Rel T9i absolutely rocks my friends 13’x14 room!  Bass that you can feel and hear as well.  Nice defined bass that adds a ton of dimensionality.

My brother picked up a pair of Sumiko S9’s for $1100 from Wally at Underwood HiFi and paired to the same Kef LS50 wireless as my friend with the Rel T9i and they are okay...  room dimensions, flooring material, and placement will play a huge role in how your Rel, or any sub for that matter, will sound.

When setting up the Rel, you should be able to tell just a slight difference in sound.  Fuller, more air and dimensionality, etc.  I can actually hear the difference a Rel makes to vocals, which seems strange to me, but I think there are many underlying deep bass notes that we don’t miss because we don’t know that they are even there, until they are.

I think you’d be happy with either a pair of T9i’s or Sumiko S9’s.  I usually prefer 2 subs over 1 since they seem to be easier to integrate in my experience.  But then again, that 1 Rel T9i absolutely rocks my friends smaller living room in a way I’ve never heard a home stereo sound.  Its quite engaging.

@lalitk  
 

dimensionality, air, presence and texture.  

 You mean made up terms? 
 
REL sells a $1200 10” that is -6dB at 28Hz, that’s insanely laughable. 
 
If aesthetics/size isn’t an issue, a Rythmik FV15HP is the same price and a much better subwoofer. It has group delay below 1cycle, a pretty good spectral decay, and passes CEA2010 THD limits if restrained to 104dB from 16Hz and up. 
 
Here’s the frequency response of the REL T5, $600 and you can’t even get a neutral response, such a shame. 
 
Here’s an HSU sub as a comparison. 
 
Frequency response linearity isn’t everything, but I expected more. 

@mzkmxcv,

So you actually have no real experience with any of the subs you criticize or endorse....should I pay heed to someone who peddles his opinions based on measurements posted on intranet or someone who actually have tried and tested the equipment....hmm take a wild guess 😉

@mzkmxcv &  @lalitkm,

I have heard a 10" SVS sealed at a friend's house paired with a pair of NHT's and with his Anthem room correct software, I was unable to detect the subwoofer.  I know this is what you want.  He set his sub perpendicular to his right front tower about 5 feet in front.  However, most audiophiles do not consider SVS to be an audiophile subwoofer.  I hear good things about JL, but I don't think I like how they work by taking over the woofers to produce bass extension.  I have heard great things about Rhythmik and their Servo technology sounds similar to REL's Speak On technology.  What I don't want is a pounding bass to drive me out of the room.  My primary focus is musicality, as I probably watch movies in 5.1 Dolby only about 30% to 40% of the time.  I respect your input.

"Can anyone hear the difference when you add REL subwoofers when playing two channel?"

Yes.
Best,
Jim Smith

Larry, 
Speakon is simply another method of speaker or high level cable termination typically found in pro audio applications. REL uses a Speakon connection at the subwoofer end only.
Servo driver control is a monitoring technology that decreases distortion in long excursion drivers. 

Introducing any basic subwoofer/s into your room/system is far from impossible and should add a welcome dimension to the presentation. It can be challenging which is why many hobbyist and reviewers have had negative experiences over the years. The acceptance and ease of signal processed units by these same people has been game changer. 

JL Audio markets the basic E series and DSP equipped F series subwoofers which they're famous for. Their differences are substantial. 



lalitk,
["I picked out REL for bass quality and their seamless integration"]
I'm interested as to what and how you compared your final choice to?
The owner of an $8900. REL Studio III we compared sold his the very next week despite our efforts using four different methods of setup. 

i added a q150 to my revel f30s, which extend pretty low, but needed some more fullness and dynamism, esp. in the midbass region. i found the rel very easy to integrate and a significant improvement.

R E L
Don't overthink it!
The Speakon connection makes a huge difference alone plus they are designed to augment music...not HT