Subwoofer Choice

I am in the process of building out my system. I have the end goal in mind, and ticking off the equipment as I get them. I do need some advice in the subwoofer category.

I am currently driving Monitor Audio Silver 500s with a Michi X5 integrated amp (600w @ 4Ohms RMS). This is way overkill for these speakers. But my purchase (coming in August) will be the Focal Sopra No. 3s.

That being said, I am looking also to add a subwoofer and I’ve settled between two (2) REL T/9x’s or one (1) REL S/510. T/9X is $1,249 vs S/510 at $2,749.

There is a REL youtube video from their chief designer comparing (briefly) the two and actually stating that "just because one S/510 costs twice as much as 2 T/9x don’t think you can equate them with 2 vs 1". I paraphrased a bit.

But the below is only 3min long please watch and let me know!

What are your thoughts. Obviously 2 subs are better balanced than 1, I get that. But given the specs here am I better at buying up for the better 10"?

Listening room is carpet, 16’ x 24’. 384sqft. 8ft ceilings. What info did I leave out?



Honestly I have not tried those models or any of the REL sub for that matter so I cant comment on its performance but i wouldn't limit yourself to one brand.

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As much as I might respect Rel, I think you should take a hard look at a pair of SVS SB1000 Pro sealed subs.  They’ll do 20Hz (-3dB) as opposed to the Rels only going to 27Hz (-6dB), and the SB1000s, like the Rels, also accept speaker-level inputs.  Plus, the SVS subs come with integration software and a 45-day, risk-free trial with shipping included both ways so you can see if they work for you.  Now, in addition to all this, here’s the kicker — you can get a pair of SB1000 Pro subs for $100 less than ONE T/9x.  I’ll take two good subs over one 7 days a week and twice on Sunday.  Hey, it’s your money so spend it as you wish, but to me the choice couldn’t be clearer, especially since you can try the SVS subs at home totally risk free.  Best of luck.

2 always two with out question. You will not need that much output for music. My JLs run at about 10-o-clock on the dial with 90db speakers. 

How do you plan to connect them? that is far more important than what sub you choose. 

Low passing them under your mains is fine but not ideal. It is complicated to get right and honestly makes things worse imo. If you highpass you can take the system to another level entirely. There are lots of cheap ways to highpass (mini DSP, etc) and more expensive two channel oriented ways (JL-CR-1, wilson sub controller, Bryston, etc). 

anyway, I would add SVS to your list. They are a better sub imo. The SB16 ultra is an impressive sub ($2300ish) with lots controls and a bit of built in EQ. They can be controlled from a phone app. I think they are comparable to the fathom line at 1/2 the price. They have cheaper options that sound as good really, you just lose features. I personally run JL which sound good but I can’t recommend them due to reliability issues. 

For me I would step down to the Sopra 2 and add a JL CR-1 (active analog controller) and two better subs of your choice and never look back. Passing to the subs around 60-80hz makes for a very impressive system. This will allow the bass to perfectly match the room as it is 100% adjustable. Looking at the Sopra’s measurements I would highpass them right around 65hz as a starting point. Try 10hz lower and 10hz higher and see what direction you like. 



Keep in mind that adding an active crossover is just another piece in the signal chain which if you are ok with that. I am not discourage anyone from not using a crossover and honestly I think it is great with the flexibility if someone knows how to dial it right.

I think that many of us have limited experience with directly comparing subs. I’ll count myself as one of this crowd, but I went through a similar selection process last year. Up front I decided that if I was going to go line level then I would want a very high level crossover like the Wilson’s, but that killed my budget. Second, I decided that I wanted a pair of subwoofers to avoid room nodes and make setup/integration easier, so I settled on REL and high level inputs. I looked at their smaller subs, but found that as I went to their more expensive subs their drivers/amplifiers became faster and the 3dB down point dropped a bit. I reasoned that faster was important when integrating with my speakers.

I'm a big fan of REL products. If it's within your price point I'd recommend purchasing a pair of the S/510s. If that's not doable purchase one S/510 now and the second one when you can afford it. 



yes agreed, adding a crossover could possibly be heard. I can only speak of the JL and my system (Mcintosh Revel) I can’t hear a change at all. If you have a very highend system maybe it would be different. The down side is good analog crossovers are expensive. Digital one are fine in theory but I get concerned about the quality of the output stage of these cheap digital units. I mean every time I change interconnects or try some “giant killer” wire it degrades my sound….


I was unable to get smooth bass (measured and heard) running the sub off the preamp crossing under the mains. But using a crossover got my room to +/- 6db in the bass in an afternoon. My bass is pretty flat now with a 6db hole from 64-71hz. I EQed out that dip but thought the EQ hurt the sound quality more than the dip so I just left it. I can’t hear that dip but it shows up on measurements. 

I have one (1) SB SVS 2000Pro about six feet behind me and once you get it set, it’s definitely worth the money. The software is the key.

Ok, the resounding consensus seems to be that SVS is on par if not more deeper and cleaner bass for the money.  I am going to go with Dual SVS SB3000s.  It's within my budget and still cheaper than 1 REL S/510.  Perhaps the REL 10" driver is quicker and better timed, but the SVS's +/-3dB at 18Hz and the fact I can get TWO seems to be a no-brainer.  Especially at $2,099.  

Does it accept high level inputs?  Someone said SVS does, or is that just the Pro series?  I can't seem to find it in the specs.


Just pick up 2 of the HSU VTF-2 MK5 subs for around $1,500.00 and you be be set or go up to the VTF-3 MK5 HP for about $500.00 more.

VTF-3 MK5 HP Subwoofer

It looks like only the 1000 Pro series has speaker level inputs. The Michi has subwoofer outs for dual subs. Each output is mono with the left and right signal summed.

Yeah, I’m pretty sure the SB1000 is the only one that accepts speaker-level inputs (never really understood why that is), but I think you can only take advantage of the SVS integration software using line-level inputs so don’t discount that as it’s significant.

I’ve owned the T-Zero MK3, T/7, T/9X, the S510 and currently have a Carbon Special. I can tell you that there is a significant jump in performance between models. That being said, @lak is on point. Get one S510 now and add a 2nd later. They are fantastic subs!


I also have in SVS SB3000. I like that you can alter the impedance curve from your listening chair with an iPhone. I’ve got it to my preference!


If you want to go line level and take advantage of being able to fine tune from your listening chair there are adapters if you only have the one pair of outputs on your pre.Male RCA with two female RCA.You can't access all of the settings from the back of the subs.The app is easy to use.

SVS make a cable for high level inputs. They are banana plug on one end and that is what plugs into the sub. Not sure which models do and don’t support it but some do for sure so just check. 

they have a 45 day trial too. Nothing to lose. 

I agree that SVS are great subs especially for convenience of the app for integrating from the listening position. Another option is the Rythmik Audio F12 subwoofer if direct servo is what you looking for with PEQ3.

@james633 The JL E112 is very impressive with the control feature. Hard to fine a sub with both phase and polarity.

One sub is nothing special. Two is a step up.

Four is ideal. Unless you can get 8 in the room!!

bound4th, considering cost and flexibility you've made a smart choice.

In my multi subwoofer experience finding your rooms bass modes by placing your uncalibrated sub in the listening position, playing a low frequency tone recording while walking your room and mapping the bass mode areas is extremely beneficial and need only be done once.

By positioning each sub in or about the two most prominent but asymmetrical modes has a huge advantage for the subs to load the room and needing the lest amount of processing and gain.

Let your ears and your personal taste guide your setup as there are no rules. The term flat response is not a goal it's simply a yield sign.

SVS is said to have excellent customer support and suggestions for setting up your presets. Welcome to the deep end. 


avatar: Gene Czerwinski



It seems to me while reading comments about subwoofers that a lot of cases describe a poor setup rather than a specific model. I have two Rythmic subs and I think they are great. I think that a good setup has a greater effect on sound quality than a specific model.

By the way, why do you think Michi is an overkill for your Silver 50's?

First I'll admit I only have ownership experience (lots of listening time) with REL.  I'm sure other manufacturers also make fine low frequency speakers.  

I have the Sopra 2

I had an old REL, a later model Strata I believe.  For its time it had a marvelous tonality and seemed like good control.  Then last year I bought an S/510 and discovered that the technology has moved forward.  

You'll find the S/510 is a tight, fast acting low frequency speaker.  It delivers the texture of the instrument, the skin of a kettle drum, brass of a pipe organ, metallicity of a an electric bass and woodiness or a stand up bass with a palpable realism that brings the lowest register we hear to life.  I would have purchased the 812, the Carbon Fiber or maybe even the 212, but I'm space constrained and so I went with the 510.  I can assure you I do not regret the choice for a moment.

If you have the room, go bigger.  if budget is the constraint then two 510's would be preferable to one larger unit.  However, if you can afford the Sopra 3, and whatever else is in the kit, then I suspect you can reach a pair of the larger subs.  What about a pair of the 212's?  I'm seriously lusting after that config.

Also, don't be so concerned about roll off.  You can adjust the the gain and crossover and can quite easily end up with too much low drive at the very lowest end, as I suspect can happen with all quality subs.  I have mine dialed in to very nicely support that lowest end of the Sopras while delivering texture and the right amount of presence.

As an aside, when I replaced my older REL I immediately discovered new texture to almost all of my music.  I listened like that for most of a year, the older REL sitting in a corner, waiting to be sold.  Then one day it dawned on me that I was being stupid and should hook it up!  So now I have the older Strata crossover set to it lowest setting.  It really only comes to life at the bottom end but gives an extra drive down there.  It especially helps with the bass presence in live recordings of bands like Phish, Grateful Dead/Dead and Company, String Cheese, .Moe, Goose etc.  It's not the perfect set up, but it makes us pretty happy!

I find the REL works quite well with FOCAL.  Look at your space and budget.  Any of the models will work.

I submit the room and what speakers you have are just important as the subwoofer manufacturer. That being said, I prefer REL Reference subwoofers. I've found that sealed subwoofers work better in my room. REL reference subwoofers are the only subwoofers that completely disappear in my room/ system. 

In my view, Rhythmiks are just as good, cost less, and have variable phase which is critical for integrating subs with room, speakers, and one another.

Well, I am using 4 JL-F-113 subs in my room. I like the JL's built in room analyzer that adjust to the peaks in the bass within the room. Each of my subs is set individually. I also an using a JL-CR-1 electronic crossover for that final setting.

I have never tried Rel’s they get some good respect in the Audio Forums, so they are probably a good sub. But... I still like the controls the JL subs have.

BTW, I am using Focal Sopra 2’s.


Why not Svs , sealed boxes are more accurate then ported or vented which Rel 

isit has a passive radiator on the bottom , I have heard  most of their models up to $3k

the most accurate which my brother has. Is the JL audio. Fathom 12 

whichhas full room correction built in. $5k retail which btw is Sealed 

the SVS ihad the SB -sealed box 3000 which was very respectable and great app for adjustment at $1k. I moved to to the SB - 4000. Which is a Big step up in output 

and tunefull accurate bass Rel cannot match especially in the $1700 range 

and  tons of bass slam not that big but very dense 102 lbs ,the driver alone os around 50 lbs , SVS gives free delivery , and a 45 day audition , plus a 5 year transferrable warranty the others Donot.  You have nothing to loose and a very good app to adjust from your chair , not the back of the sub .

IMO with your system you need to consider what will play better with your components. One thing that stands out to me when looking at specs is the amp design of the subs. Rel is class A/B and SVS is class D. I tried both and went will the Rel as I just could not get the D amp to disappear in my system. When listening I could always locate the sub no matter where I placed it. Then I tried the Rel and it just became an extension of my Vandersteen’s. Subs are self powered so don’t over look the amps difference between brands.

Audition the RELs and put your hand on the enclosure. You will feel it shaking. That is distortion. Audition the Martin Logan and KEF balanced force subs. When you put your hand on the enclosure you will feel almost no shaking. These are significantly superior designs. The KEF even has a full two way crossover. Magico uses a similar design but they are very expensive. 

You have a fairly large room. My room is also 16 feet wide and I use 4 12" subs. The absolute minimum is two 10" units. I would not go any lower than two 12" subs or equivalent. You will also need a complete 2 way crossover. 1/2 the benefit of using subwoofers is removing the bass from the main speakers. This allows you to use a higher crossover point and significantly lower distortion in your main speakers along with adding up to 6 dB of headroom. Most commercial subs only have a low pass filter. You can high pass the main speakers by soldering a capacitor of the right size in series with the input. The capacitor value depends on the input impedance of the amp and the 3 dB down point (crossover point) you want to use. C = 1/RF Digikey will sell you any capacitor and your amp's manufacturer can tell you the input impedance (R) of your amp. 

I have two REL T9is.  I think they are particularly musical, well built and a great value. I’ve tried other stuff but kept coming back to REL.  I do wish REL had an APP but I get their reasoning for not going that route. 

Last year I purchased the SVS 1000 pro  and a Polk Audio dsw micro 3000 in a 14 x25 foot room and for me it wasn’t enough bass.this year I purchased a monolith with dual 10”woofers and it fills the whole room with no problem.

+1 @lak , go for the S series. I haven't listened to the T Series, but have listened to the S Series and currently have a pair of Carbon Special.  A lot of T series are for sale on Audiogon and USaudiomart, wonder why they don't like the T series anymore.

I own Sopra No2s


Congrats on the purchase of the No3s.  I have a fully treated room w/ bass traps and a JL F112v2.  I find that the Sopra's alone do a great job with a good recording.  If the recording is thin I'll activate the sub to correct the recording.  I don't pay attention to stats, they mean nothing to me.  From real experience, properly positioned and adequately driven, the Sopra's will make a ton of bass.  They are front ported and have a good deal of speed IME.  Be sure to match the speed with the sub.  Speed isn't about size, it's about quality of the driver and power/electronics.  I have two (2) SVS SB4000s in my HT room and IMO the JL is considerably faster.  I the JL makes more power and has a large toroidal transformer that the lower priced SVS does not.


Probably more than other speakers, the Sopra's are sensitive to the grip of the amp.  Pairing your No3s with an amp with a very high damping factor will give you crap ton of clean, fast bass.  


I would get the new speakers in place, run them in, and then decide what your needs really are.  Set up properly with a good source the No3s will be darn near full range.  Again, I always disregard specs and trust my ears.  Good luck and cheers.

Thank you for so much good information, this forum never disappoints and is always so knowledgeable!

So, after further thought (and contrary to my follow up post above) I decided to stick with the REL and buy up to the S line.  I picked up two S/812s.  Maybe the JL hits harder and lower, but hopefully I'll be just as happy with the 812s.  

Someone mentioned the JLA CR-1 which I was considering.  However, can i use it with my integrated amp (Michi X5)?  I don't think i can pre-out and then back in to the same amp can I?

Thank you



@james633 @ozzy 


@bound4h , The JLA crossover is a good analog crossover however the best sub management systems/crossovers are digital. Check Out MiniDSP which makes several reasonably priced units. They also have room control features, Dirac Live I think. There are now several digital preamps that have sub management, room control and EQ built in, MiniDSP, Anthem, DEQX and Trinnov to name a few. 

All subwoofers that have only one driver are compromised by Newton's third law. Sub drivers are heavy and play low frequencies at higher volumes will cause the entire enclose to vibrate/shake. This creates distortion and compromises dynamics. It does not matter how heavy the enclosure is. You just raise the frequency the enclosure shakes at. Some manufacturers have taken this into account in newer designs that use two opposing drivers that balance each other eliminating this shaking problem. KEF, Magico and Martin Logan all make "balanced force" subwoofers. 

I would also add, I had way better results with down firing subs. Much easier to match and place them.

Hey, congrats on your new purchase and I’m sure you’re gonna be thrilled.  Can’t go wrong with Rel IMHO.  Let us know how it goes. 

@bound4h Congratulations on your new purchase, I'm sure you are going to be very satisfied. The videos available on YouTube that REL make are very helpful regarding break-in, placement, and tuning. Please let us know how the music is sounding once you complete the setup.

Dude, when did JL Audio become a consideration?

You'll be just fine with a sub-bass speaker. What you don't know can't hurt you. 


All the best.




6,498 posts


As much as I might respect Rel, I think you should take a hard look at a pair of SVS SB1000 Pro sealed subs.  They’ll do 20Hz (-3dB) as opposed to the Rels only going to 27Hz (-6dB), and the SB1000s, like the Rels, also accept speaker-level inputs.  Plus, the SVS subs come with integration software and a 45-day, risk-free trial with shipping included both ways so you can see if they work for you.  Now, in addition to all this, here’s the kicker — you can get a pair of SB1000 Pro subs for $100 less than ONE T/9x.  I’ll take two good subs over one 7 days a week and twice on Sunday.  Hey, it’s your money so spend it as you wish, but to me the choice couldn’t be clearer, especially since you can try the SVS subs at home totally risk free.  Best of luck. 

You must be kidding? Those SVS subs aren’t allowed in the same paragraph as the REL’s mentioned. 

I have a pair of REL s/5 SHOs and they absolutely disappear.  Rel makes some excellent subs.  


My suggestion would be to go with four Rel T7x's positioned as a distributed bass array.

Do some research on bass arrays. Best bass I have ever had.

Hi bound4h...thanks for the topic.

I've spent most of my 40+ hi fi years with larger monitors and no subs in several rooms.  My Chapman T-4's dug into the 30hz region and I was always quite happy.  In the last 23 years, in my dedicated studio, I've experimented with subs and better monitors...Salk Veracitys and my present Revolution Be's...discovering subwoofers, indeed, add refinement to the ENTIRE frequency spectrum.  In the last several years, I've used a pair of Paradigm Ultracube 10" sealed subs beneath my monitors, with careful isolation.  This, in essence, created a "full range" presentation in a small space.  

Recently, one of my Paradigm subs failed.  To my great surprise, using ONE subwoofer increased the quality of my sound, to all parameters!  Since the surviving sub is also showing sign of failing, so I've been doing a deeper dive about subwoofers in small rooms.  A friend, with equivalent experience, said ODD numbered subs work better in small rooms.  I've researched "swarms" of subs, but that's simply too complicated in this small space.  

Jeff, my long-time audio Tech friend who has much experience both building and helping others with subwoofers has recommended the Rythmic L12 Direct Servo subwoofer.  "Speed" in the context of subwoofers for music vs HT, is a topic worth researching, relative to start and stop timing and decay.  A "direct servo" addresses that for music.  Jeff also prefers larger drivers working less and quicker. 


I also have a preference for the musicality of "paper cone" drivers, so the Rythmic L12 is on order and on its way to me.  This will mean a change-over to conventional loudspeaker monitor stands and finding the sweet-spot for a single subwoofer, in my studio.     HUZZAH!     After all these years, I continue to be excited and recharged by chasing better sound.  Like springtime, everything gets refreshened.  Will report back further down the road.  

(bold print for old eyes)      More Peace.       Pin

May I suggest Monoprice's Monolith Subwoofers!   They come in all different sizes and price ranges and they're top of the line can often be caught on sale.  Besides being very reasonably priced their quality is top notch which you can read all about them in many reviews.  I personally just purchased their 2,000 Watt Dual 15" Subwoofer which although I still haven't or hooked up because I have pneumonia keeping me down, I've done my all my research and am quite satisfied with their Customer Service and my prior interactions and inquiries.  


Great post, pinthrift. Looking forward to your impressions. I bet it’s going to be fantastic.




I put together a system for my daughter that has the Monitor Audio Gold 50 and Rel  Tx9.  They mated well together


it does not look like the Michi will support the CR-1 crossover. You would need an amp input. Does the michi have bass management built in? Looks like it has a sub out.