Pair of Rel S510’s or Carbon Special’s?

I say, buy the most expensive REL you can afford. Of course, bass quantity is important, but IMO the most important quality of a music-focused sub (like REL) is speed. The drivers have to be very quick and must start and stop on a dime.

Based on my listening, I think Carbon Specials will give you more speed. And I say this as someone who owns a pair of S/510s which are no slouch either :)

Good to know, thanks. Have you heard the Carbon Specials in comparison with your S510’s? Based on their specs I’m sure the Carbon Specials can go deeper and louder, with greater speed, but in my case I only plan to have the subs add very minimal effect. I’m not actually looking for deep full bass you can feel. Just a bit of lower end QUALITY support is all I’m after. But maybe the added speed and detail of the Carbon Specials still matters in my application? Or maybe the difference would not be noticeable?

I should say up front, probably all I need is to activate the EQ in Roon and boost the lower frequencies a couple of decibels.. But due to my irrational audiophile sensibilities I can’t even bring myself to try turning it on! Don’t want any app messing with the purity of the source material!

I have 3 s510s in my room....I'd go with the 2 carbons if you can swing it

Rythmiks have adjustable phase which is very helpful for dialing in the subs and you are not paying the premium for a REL. My experience.

"I was able to get results that I could live with from any position I tried; thanks largely to the flexibility offered by the F12SE's broad array of setup options. In my case, "results I could live with" means a smooth transition between mains and subwoofer, bass that doesn't localize to the sub, with standing wave peaks minimized (or eliminated). Getting back to the Rythmik's setup options, there are too many to catalog them all, but here's a few that I found most interesting/useful:

Low Pass Filter: Unlike most subwoofers that have a single knob that selects the crossover point, Rythmik provides a switch that selects a general crossover point as well as a 2nd (12dB/octave) or 4th (24dB/octave) order slope. Meant to be used to determine if the subwoofer will be receiving a full-range or a bass-managed signal, it's also useful for mating with sealed or ported speakers, each of which roll-off at different rates. A crossover knob is also provided for fine tuning.

Delay/Phase: I'm not sure if this is any different from a typical subwoofer phase adjustment, but Brian has a completely different approach to how this should be used. Instead of simply setting it where the output is loudest, he provides a formula on his site for setting it based on the subwoofer's distance from the mains by adding delay. Of course, delay can only be added (subtracting delay would require time travel), so nothing can be done to correct situations where the subwoofer is farther away from the listening position than the mains.

Parametric EQ: Extremely useful, and by far my favorite feature. Parametric EQs are common in high-end subwoofers, and I never want to be without one again. Standing waves will forever be the enemy of smooth, well-integrated bass as long as you are listening indoors (and your audio system isn't in a barn). The EQ made quick work of taming the nastiest of these peaks in every placement the F12SE found itself in."

https://www.enjoythemusic.com/magazine/equipment/0709/rythmik_f12se.htm

Take a look at Perlisten subwoofers.

D212s (dual, push pull, 12" carbon fiber woofers), 3.0 kW amp (retail $7,000), or

R212s (dual, push pull, 12" glass fiber woofers), 1.3 kW amp (retail $5,000)

There is also the D15s (single carbon fiber 15" woofer, 2.0 kW amp). Retails for $5,000

Subs will be positioned about 6” on the outside of each main speaker. This is the ONLY place they could go…

The chances of this being the optimal placing for the subs is small.

probably all I need is to activate the EQ in Roon and boost the lower frequencies a couple of decibels.. But due to my irrational audiophile sensibilities I can’t even bring myself to try turning it on! Don’t want any app messing with the purity of the source material!

Are you serious?  Think how many times the digital signal has been manipulated before it even gets to your streamer!

@onhwy61 , you are right, I am a bit worried about positioning.  But I’m hoping the big open room makes the one available position okay.  There are no room corners to consider with my open concept house.  But there is an island on the left and another obstacle on the right that limits the position of the subs to 6” on the outside of each speaker.

@nyev 

I am a bit worried about positioning.

This is why my post about Rythmik is quite pertinent to you. If you are already married to REL, then you can disregard. I have both. They both sound good, but Rythmiks solved the room integration puzzle.

@hilde45 reading the link now, thanks

@hilde45 , interesting subs and delayed phase feature, but to me it sounds like in my case I shouldn’t need a delayed phase feature since the subs will be practically in the same spot as my mains.  Seems to me this would be useful for when your subs are further away from the listener than the mains…

I have been there and was an owner of the S510 and now JL. I have a few thoughts about your situation based on my experience:

1) The S510s are too small for a large room with large speakers.

2) I would try the DSP function to see if you can get what you want. Its free and easy. That would be a way better solution than subs. I do not have Roon, though.

3) I would be personally be inclined to take advantage of the Diablo’s sub outputs and get a different brand of subwoofer. REL company encourages high level inputs on their subs. Not the biggest deal. I found low level inputs are more user friendly, plus it eliminates any possible annoyance with pops and noise.

4) There is no substitute for positioning subs correctly. The room will dictate it. I do not know if you will be lucky. REL has an approach of coming in with the bass at a lowest volume level and frequency and time aligning with the main speakers based on moving the sub or speaker forwards or backwards. JL Audio is different in that the goal is smooth frequency response phase centered around 80Hz suggested crossover point and phase control setting.

5) The idea of ’speed’ (lack of resonance?) of the subwoofer does not matter unless the subs are well integrated in to the room.

I have both Carbon Limiteds and Carbon Specials in my two systems.

Both are wonderful and are so much better than my previous Paradigm subs and many I have heard.  I try to avoid the DSP.   I get the word ONLY in where they are going.  I said that.  But moving them one into the corner and one into the side made huge differences in eliminating room nodes.  Like you said and others, feather them in very slightly.  They add foundation and improve everything.  You miss them when they are off!

@ohlala thanks for your perspective.  Regarding the S510’s being too small for my large room and speakers, I think you are right.  But, the fact that I am not feeling the need to fully energize my room with bass, and just wanting to add a bit of slight bass support, that might make the S510’s okay for my application?  And, might make placement easier too, given that I plan to have their output set low?

@nyev 

 interesting subs and delayed phase feature, but to me it sounds like in my case I shouldn’t need a delayed phase feature since the subs will be practically in the same spot as my mains.

Mine are, too, but in order to deal with room modes, the adjustment on delay/phase is not identical on the two of them. After I positioned them, optimally, I then discovered that in order to get the best bass response, they need to be set differently; one wants to be at about 120 degrees and the other is at about 165 degrees. A REL would only allow 0 or 180. 

I’ll echo what others have recommended. If you can afford the Carbon Special then go for it. I went from a T-zero mkIII —> T9x —> S510 in a relatively small room and I’m looking to move up to a Carbon. It’s a significant performance jump from the S510.

@hilde45 

You are correct. I have Rythmicks too. The phase setting came out real handy when I realized having both subs by the mains did not work in my house of stereo as it produced incredibly loud rumble along the back wall. So at the recommendation of someone here I moved the left one down a third of the length of the left wall and with the phasing dialed in for this one, I no longer had any spot in the room with overly booming bass. I remember MC saying back then that phase adjustment didn't matter. That's when I started taking everything he was saying with a grain of salt.

Rythmik subs
F12SE-XLR3 piano black, A370XLR3 amp.

Sorry, couldn’t help myself. :-)

I understand brand loyalty so if you like REL then who am I to say otherwise?

A while back someone posted that they thought that REL subs made other subs look cheap by comparison. Really? If I had feelings, they’d be hurt. :-)

To his point, I really like they way mine look, otherwise I wouldn’t have bought them.

For pure performance, I wouldn’t overlook direct service subs.

I’ll apologize in advance in the event my post is less than helpful.

I was under the same choice considerations last year. It wasn’t about price, it was about size and sound. My ego said REL Carbons. Long story short, I ended up with dual Rythmik F12SE’s. Mine are paired with Revel Ultima 2! Studio 2’s. They aligned well, they are tight, they are integrated well. Reminds me of when I bought my Genesis car.

What would Miller Carbon do?

Very interesting comments on the subject of adjustable phase.  I was thinking that if some speakers have powered subs built in, that is the closest thing to having subs next to the speakers.

@nyev I have a pair of REL T/9x's paired with Harbeth 30.2's and I'm really happy, they just add a little bottom end energy. My comments are set up related only...

- Placement close to each main speaker is desirable. They are acting as extended bass drivers not surround-sound sub-woofers.

-Based on the above, phase is irrelevant. Set to 0.

-The high-level Speakon cable connection is recommended to reduce support calls because EVERY amp can support this method. The way to go is a line level rca stereo sub-out but obviously not all amps have this feature. This was a significant consideration when I recently upgraded my amp, I went with Raven Audio. All you need is a good quality pair of stereo RCA interconnects that come as a separated pair (E.g. Raven's). Don't waste money on overpriced subwoofer cables.

-If you have to use the supplied Speakon cables, trim them. If you still end up with a hum after floating the ground (or not), feel free to private message me for an easy fix.     

Thanks @macg19. My amp does in fact offer RCA connections specifically for subwoofers. However Rel claims that the high level inputs are better because then the subs are in perfect sync with your speakers, as they are getting the same signal…. Also, I’d think the low level RCA run would not be good for a low-level signal vs a high level speaker signal? My perspective is 100% influenced by marketing and things that sales guys have told me for many years in HiFi shops. Sadly I don’t think I can recall any good advice from a well-meaning but misguided sales person.  Many years ago a salesman told me that the high level Rel connection offloads your main speakers thereby improving performance, while automatically adjusting to a seamless crossover point for utterly perfect integration. I always remembered how passionately he was telling me this, which I always thought was BS!

@nyev My pleasure. Good news on your RCA sub-outs. The high-level input driven from the speaker binding posts passes through a resistor that essentially turns it into a low-level input anyway. Note that gain control on the REL is the same for both high-level (Speakon) and low level (RCA) inputs. (There is a dedicated RCA input with it’s own gain control but that is only for low-level .1 surround sound). There are zero issues with using the RCA low-level inputs unless your RELs are really far from the amp.

I a/b tested high and low level when I got the new amp and there is no question that in my system the RCA/low level sounded better.

Miller Carbon would buy 6 more subs.

This has been a very helpful exchange.  I have resisted subs for for more than 40 years (since they started?) and am still doing so, but every now and then I am tempted in to have another look, as here.

@nyev , all the little details about power cords, which sub model, high vs. low level connections, phase control, etc. are all secondary to proper subwoofer positioning.  If your subwoofer position is wrong, then the other stuff won't even matter.

A simple test would involve moving your current loudspeakers to the proposed subwoofer positions and run a series of bass tones to evaluate.

@baylinor ​@rhg3 ​@onhwy61 ​@nyev 

The phase setting came out real handy when I realized having both subs by the mains did not work....I moved the left one down a third of the length of the left wall and with the phasing dialed in for this one, I no longer had any spot in the room with overly booming bass. 

I understand brand loyalty so if you like REL then who am I to say otherwise?

all the little details...are all secondary to proper subwoofer positioning.

To add a bit about my experiences. 
I have both REL and Rythmik. I had REL alone for a long time and moved it everywhere. I even tried putting it 4 feet in the air (tricky) and measured that position in various places. In the end, the REL sounded good but various problems were ineliminable. 

I added two Rythmik subs and started moving those all over the place. I had a backache every day for weeks. Seriously. Positioning was not enough. Something more was needed.

The breakthrough was placement of the Rythmik subs a bit behind my mains AND playing with the various levels (gain and phase) until the bass from 20-300 Hz was within 5 db of the average. The REL is connected with Speakon but it's out near the listening position with the crossover set much higher.

Bass bloat went away, things got full and tight, and the subs disappeared.

People with REL's have good experience and report them; often, they overestimate how universally applicable REL's might be to a particular situation because of brand loyalty. That does a disservice to the OP, here, because what he will have to do is buy multiple (more expensive) REL's to dial in his room. (Which might not even work, and then he's looking for bass traps.) Only someone with a dream of being a REL fanboy would fork over that much dough; if a sonic goal is really what is sought, one gets over brand loyalty. After all, if one had a boat they needed to tow, would they buy the brand they liked or the one which could actually tow the boat?

I would go with the largest REL's you can afford.  You can always dial them back.  I still thin the high level connection designed by REL is incredible.  

Given the OP is not interested in Home Theater, and not looking for earth-shaking bass, the largest may or may not be the best for his specific application and objectives.

According to my local Hi-Fi dealer, he stocks the T/x line because they are designed with a focus on stereo music applications (he doesn't sell Home Theater equipment). The REL online speaker finder and marketing language support this.

Other models are clearly Home Theatre focused. 

Question for OP -- is your goal unequivocally to buy a REL or to create the best bass response possible in your room? Many posters here only mention or advocate for REL, so I may simply duck out of this conversation. 

@hilde45 : judging by the original post / thread, and the subsequent posts from the original poster, I think he is set on REL. Obviously, there is absolutely nothing wrong with that.

Are Velodyne subs not rated in the US?

+1 hilde45, when i get a notion to respond to the OP's slightly unusual goals or the entusiastic brand fans you chime in and I chuckle in agreement. 

I so empathize in dealing with the shear stoutly centerd weight of most subwoofers and ones ever diminishing abilities. My subs and Bass amps/cabinets are on wheels. I don't leave the house with anything bigger than my tom drum sized upshot 10" cabinet and cigar box sized switching amp. 

I'm enjoying a notcable differnce in the presentation of my two main system subs which are now on DYI foam topped platforms with large soft foam casters. A stunning reduction of low frequency energy migrating through our homes structure and slightly better definition at the listening position. 

Anyway, ask for help and bend those knees.

M 

@m-db  @thyname 

Thanks -- I can see that the main goal is ultimately to buy a REL brand product. I was confused because the OP mentioned "speed and bass definition and quality...positioning constraints...and precision, ambience, clarity and space" Thus, I thought achieving those acoustic goals might supersede buying REL, but I guess not.  

Hi, with respect to advice I get on these boards, I pay attention to individual advice, but I ALWAYS ultimately pay attention to consensus.  I find it is the only reliable approach and it has led me to some very positive results.  For example, I’d never heard of Gryphon before and was failing to find an amp that made my speakers sound better than mediocre.  Then I heard about Gryphon in these boards, and it seemed like almost 100% of people were going on about how great The Diablo 300 was.  Even the “My long list of amplifiers” dude had a spotlight on the Diablo 300 for a while, saying there was nothing, separates or otherwise, that bettered the Diablo for $50k or less.  At that point I made the effort to trial the Diablo and I was stunned at how my speakers came alive, with zero annoyances in the tonal balance as I was finding with every other amp / preamp I was testing.

All that to say, my goal is quality and I am not at all tied to Rel. Going back to consensus, the reason I started with Rel is there seems to be a lot of folks who say they are great.  That said, I’m sensing there may be more people who aren’t so happy with Rel.  In the case of my Diablo 300 amp, I think I’ve found maybe 3 posts tops where people aren’t liking what they hear, amid a sea of praise (which I would happily add to).

@nyev REL makes fine products; they're also quite popular. I love my REL. But the issue for you is the constraint placed by positioning and whether REL's -- for their price and lack of flexibility with settings -- can get you where you want to go. You're hearing from those who love their REL and some (like me) who love their REL but don't think that a REL is necessarily capable of working in every situation.

when i get a notion to respond to the OP's slightly unusual goals or the entusiastic brand fans you chime in and I chuckle in agreement. 

I so empathize in dealing with the shear stoutly centerd weight of most subwoofers and ones ever diminishing abilities. My subs and Bass amps/cabinets are on wheels. I don't leave the house with anything bigger than my tom drum sized upshot 10" cabinet and cigar box sized switching amp. 

I'm enjoying a notcable differnce in the presentation of my two main system subs which are now on DYI foam topped platforms with large soft foam casters. A stunning reduction of low frequency energy migrating through our homes structure and slightly better definition at the listening position. 

Anyway, ask for help and bend those knees.

This reminds me of a Kamala Harris speech.

OP was particularly asking for comparisons and feedback for two specific REL models. That's why some of us stayed within the parameters of the initial ask. It doesn't mean we believe that REL is the only game in town.

Anyways, I still feel that driver speed is much more important than sheer bass output for subs dedicated to two-channel listening. This is exactly why REL is preferred over other HT-focused brands, despite much lower power output. But I agree that they need to do better to help with placement flexibility. I don't understand why they only provide 0 or 180.

+1

macg9, as an Oakland, California native that's a fine complement. Thank you. 

@m-db From a San Clemente California resident, you're welcome.

@hilde45 , back to the subject of phase, isn’t the goal to have sound from your speakers arrive at your ears at precisely the same time as the sound from your subs? And if the subs are directly beside your speakers (which is similar to the case of speakers that include powered subs), would the timing for sound from your speakers and subs to travel to your ears not be identical? I’m trying to understand the rationale as to why having the drivers of the subs be out of sync with my main speakers might be beneficial - I can understand in the scenario of when your sub is significantly further away from your speaker.

Finally, having your subs directly next to your speakers and being slightly out of phase from your speakers, wouldn’t the significant vibrations from the subs adversely affect the performance of your main speaker drivers, by having a slightly deleterious effect on each other? When people question how powered subs can be embedded in speakers without having a negative impact, I’ve always heard the argument that it’s because the vibrations are perfectly in sync and are therefore working together. Is it possible that having the crossover set too high amplifies the lower frequencies too much causing the boominess, and by having the phase set slightly apart, your speaker drivers and sub drivers are very slightly taming the bass response by slightly cancelling each other out?

I have no experience in this area or with subs in general, so I’m just trying to understand. Or is it one of those audiophile things that don’t make any sense, but it helps? (like for example I recently learned that 2m USB cords are vastly superior to 1m cords, when I tested 0.75m, 1m, and 2m versions of Audioquest Diamond and Nordost Valhalla 2 USB cords - makes NO sense but wow is there ever a difference!).

macg19, San Clemente, very nice. Do you know from lowers?

OP, the subwoofers produce waves that bounce around the room. The simple picture of a sub placed next to speakers doesn't do the complex physics justice. Take a look at this thread from 2021 -- there are many good posts on it.