Sub Confusion

Over the years I've always preferred 2 subs, helps solve some bass node issues, but recently have now done without subs. Less integration problems

As rsf507 states, multiple subs tends to resolve node problems. Google "subwoofer swarm" for an explanation for why multiple subs are usually better than one. 

Your reason for wanting to free your speakers from reproducing the lows, is one  great reason for adding subs, Mids and midbass will improve noticeably.

What do you mean when you say you are not looking for 'more bass'? 

I ask, because there is more ambient information in low bass than many people realize. Adding bass down to the lowest octave, opens up the soundstage. 

"My goal is not more base- I’m looking to free my PMCs from having to expend energy to produce sound below 80 Hz and increase depth."

To do that you will need a sub with a high pass filter. You need to use a separate amp and preamp or an integrated with preamp out and amp in!

If you use Rel subwoofers, those don’t have high pass filters!

What Yogiboy said. Adding subs doesn't automatically make life easier for your other components. I think your speakers are transmission line designs. Removing sub-80Hz signals will mess them up. You need to rethink what you're trying to do. 

As mentioned, the 212/sx is designed to run in tandem with your main speakers (no high pass).

Generally, stereo subs would be preferable. That said, i have a single 212/se in my system and don't want for anything below 80hz, so there is always more than one path to satisfaction.

I agree with just about everyone’s posts. That said, 80Hz high pass might be a bit high for your speakers considering they can dig down to 26Hz. If your goal with subs is to clear up the frequency spectrum and deepen the soundstage, you likely want them performing largely below audible frequencies and will want two or more in the room.

Even without a high pass, you will be surprised what two good subs crossed over at 65Hz or lower will do to the rest of the spectrum and to the sound stage. Should you still want to combine this with a high pass for your speakers, I suggest looking first at a 60Hz high pass as 80Hz may be too high.

While the Rel 212 is a wonderful sub, it is a lot of a single sub for that room. The others you mention though do not dig deep enough. I would probably opt for two 812’s, and if that’s too much money, the SVS SB-4000 is a worthy competitor at a fraction of the price and offers better integration with its mobile app.

In full disclosure I run a hifi business but do not carry Rel or SVS. 

"SVS SB-4000 is a worthy competitor at a fraction of the price and offers better integration with its mobile app."

Ummmm do SVS subs connect via the main amps outputs? I dont think so. the above statement will never be true, just because theres an APP? Thats not how subs integrate.

The REL subs connect through the main amplifiers outputs just like the main speakers for true integration and you dont do this using Hpass filters either!

If you need more than one sub your using the wrong subwoofer.

And to answer the OP's question YES the S510 will be plenty for your room size. I would buy it in a heartbeat. And make sure you set it up as REL reccomends for best bass response and musicality......YES REL's do more than produce bass they are musical and when tuned in properly they make the main speakers come alive even more and allow them to play with more detail and ease. REL subs sound beautiful.

Thanks

Matt M

Thanks to all for the valuable input. When I said I didn't need more bass, I meant what blisshifi said is exactly what I meant- "to clear up the frequency spectrum and deepen the soundstage". However, blisshifi, mentioned that other than the S812, the others don't dig deep enough. I know there's a difference between the S812 and S510; however they are both -6db, with the S812 at 19hz vs the S510 at 20hz. Given that, and based on my room size, wouldn't it be wise to start with a S510 as suggested by Matt M (setting the crossover at 65Hz)? 

Vandersteen sub3 w high pass filters if your integrated has pre out / power in. Better bass and mids….especially the mids….

@thebingster IMO that last Hz matters more than it appears. Those measurements  are at -6db. In reality, the S/812 is likely more like 24hz at -3db and the S/510 is probably 29hz at -3db. Both are not great measurements compared to many subs that dig much deeper, but Rel is known more for its speed than its ability to dig deep (aside from its reference products). 

Thanks @blisshifi for that info. And for clarification to others, the DarTZeel integrated does not have a pre out, so sub(s) will be connected to the main amp outputs. Looks like I should start with one S812, and save up over time for a second.

Another company offering subs with high-level hookup capability (the sub taking it’s signal off the power amp’s speaker binding posts) is Rythmik Audio, in their non-XLR plate amps. Those plate amps offer both high-level and line-level (from a pre-amp’s outputs) connections.

Available models include 12", 15", and 18" woofers, in both sealed and ported enclosures. All models employ servo-feedback circuitry.

The claim that an amp-level connection is better than a line-level connection for subs is an opinion not universally held. I have heard really excellent systems with subs that were connected via line level. Line level allows the possibility of a line-level crossover for mains and subs, a very flexible way to arrange things. Also, in most domestic rooms, the EQ provided by subs with PEQ apps will be of real value in getting smoother bass.

Another extremely valuable item on a sub is a continuously variable phase control. It is the only way of getting the smoothest (flattest) bass from a sub in a given position. The more overlap between sub and main, that more correct phase matters. I wouldn’t pay a lot of money for a sub without that feature. A +/- polarity switch is better than nothing, but no substitute for a proper phase control.

I agree that in most cases, two subs are better than one. By better, I mean capable of providing flatter and more natural bass response.

I'm in agreement with bdp24.  Having owned both the Rythmik subs will do want you want as well or better than the REL's and a pair will cost you less than one REL.

Passive Subs. 4 small ones.

@jackd: And, all the Rythmik's have what @mike_in_nc wants: a continuously-variable phase control, providing anywhere from 0 degrees of phase "lag" (no delay) to 180 degrees (16 milliseconds of delay, which does electronically what moving your sub back 16 feet does).

And @jackd, Rythmik's Brian Ding himself prefers and recommends line-level hookup over high-level, though as I said above he does provide high-level provisions in his non-XLR model plate amps.

My room is about 20'x30', moderately damped with speakers on long side. REL s/510 is more than adequate. 

+ @noromance 

+ @bdp24 

+ @yogiboy 

I have a REL. I have Rythmiks. Both are good subs. Rythmiks are better values and more integrateable. You could have a couple Rythmiks and a better integrated room for the price of one new REL, IMO.

Agree with those that suggest Rythmik offers better value and can be integrated better than REL.  I have nothing against REL subs, but they don't represent a good bang for your buck.  If you have the money and like audio jewelry, by all means get a REL, or better yet, 2 or 4.  Just realize you're paying more for looks, their huge marketing budget, and dealer markup than you are for superior technology. 

A pair of well set up Rythmik subs will make your system sound better than the one REL sub you would get for the same amount of money.  A well set up Rythmik (or many other brand) sub(s) will be "integrated" just as well as a REL sub.  A REL sub can be poorly set up and sound boomy or not well "integrated".  All this nonsense about the way it connects to your system making a huge difference is just that.  You either know how to set up your subs regardless of what brand they are or you don't.  Rythmik and many other subs provide you with more setup options than REL.

@thebingster , There is no such thing as overkill, only underkill. If you can fit larger subwoofers go for them. 

You are right on about removing the bass from your main speakers. You will lower distortion and increase headroom. You will however need a 2 way crossover but you have a problem. Digital cross overs are way superior to analog ones. You want to stick the digital crossover in front of the DAC so you are not going back and forth between digital and analog. You only want one conversion. This means you will have to get another DAC to handle the subwoofer channels. It is only handling the bass so you can use a much less expensive one. There are many companies that make digital cross overs and some of them also have speaker control (room control is really speaker control) This allows you to digitally equalize both channels so that their frequency response is exactly the same improving your imaging. While you are in digital you can do almost anything without adding artifact of any kind. The best sound I have heard coming out of my system starts with a digital recording and stays in 24/192 digital until it gets to the amplifiers in my system. The clarity is stunning. I can get close with my turntable but not all the way there and I do not think it is possible to get all the way there. This does not mean I do not like records, I buy one or two every week on average. Records can sound better than digital versions by virtue of the mastering. However, the clarity is always a bit better in digital sources. Digital can be more dynamic than analog sources also. These are gross generalizations that can be violated by the quality of the equipment. If you use a SOTA turntable and phono stage against a Walmart DAC of course the vinyl is going to be better. 

@thebingster,

Adding a sub see Soundoctor below: 

Mike

http://www.soundoctor.com/whitepapers/subs.htm

No idea why people have such a hard time integrating any sub. I have had REL and SVS as well as ML and never had an issue. Takes time and a bit of fidgeting.

@ditusa thank you for the link love this type of information. 🧐

To be frank, looks are important to me and the REL looks business. The REL made other subs look cheap in comparison although I understand it’s the sound that matters. To me both are equally important, and the REL does not disappoint when it comes to performance.

Try not to go below S510 if your speakers are between $5k to $10k.

My S510 sits dead centre between the speakers in the middle of the room.

@ryder what's cost have to do with the performance of a stand mount or a floor standing speaker. I think with question would be the performance of the drivers and their ranges. Not $$$$$$$$$$$$ Also this will be room dependent, size and treatments.

Some may find this beneficial . https://www.whatsbestforum.com/threads/2-channel-subwoofer-integration.33653/

My room is much bigger with 15' ceilings. I have Zu Audio Dirty Weekends. I use one REL T7x. It is astonishing. Start low you can always add.

You could try HSU subs their 2 top of the line subs are reasonably priced and have both high level and low level inputs

You can email or contact REL customer support and speak to 1 of their technical support staff. They were most helpful when I was changing out my equipment and integrating my existing RELs. John Hunter and staff are true audio professionals. 

Iam looking into Audiokinesis SWARM sub system. according to some owners reviews they give the listeners to be immerse into the music.

@jayctoy I have not heard the "Swarm" but it appears to be a great plug and play solution that is reasonably priced.  You can use just about any sub to get that "immersive" experience, as long as you have them set up in a distributed bass array.  In my case, my distributed bass array, or "swarm" if you like, consists of two Rythmik subs and two SVS subs.  The Swarm is a nice option that I would have given serious consideration to if I had found out about it before I bought the subs I have.

Big_greg The review of Robert Green is so impressive.

I use a B&W DB3D located behind my rig firing the drivers to the side walls. It supports my A5's at the low end and pressurizes the room at the same time. For me, the perfect sound.

I'm currently using two Martin Logan Dynamo 700s which are 10 inch sealed subs.  The system sounds very good.  I have an opportunity to get a sweet deal on a B stock REL S-812 (40% discount) 12" driver plus passive radiator.   I have always wanted to upgrade to Rel.  I'm wondering if single 812 will exceed performance of dual Martin Logans.