Which subwoofer?

2 x REL T5x would be perfect. 

I assume you listen Nearfield.
I have a 13' X 13' room and use three subs.
It works nicely because of the Nearfield listening method.

Also definitely recommend stereo subs.

GR Research has many planar loudspeaker owners (myself included) who have found musical happiness with any one of their subs. Look into the model F-12G, designed in collaboration with Danny Richie of GR Research (hence the "G" in the model designation).

If you are REALLY serious, and are up to a little DIY, the Rythmik/GR Research OB/Dipole Sub is THE sub for use with dipole loudspeakers. Details on the GRR website.

The REL looks interesting, but I have what is probably a stupid question. The REL t5x goes down to 32 hz and my Martin Logans go down to 34 hz. Will I notice the additional 2 hz of bass energy?

Thanks for your responses. 

@kenrus , you wont, its the quality of the base rather than 2hz either way that matters most.

How about looking at used ML Descent i’s , I recall a number hitting the classifieds when the newer models came on line.

https://www.svsound.com/

Very good quality and reputation also offer a lengthy trial period along with free shipping TO and FRO. 

Chuck 

I do own a couple of great but older REL subs (B1, Storm III) but recently acquired three sealed SVS subs, one SB-3000 and two SB-2000 subs (close-out). I'm very impressed with the modern technology.

I owned SL-3s as main speakers for 16 years (still have them) and if your bass quantity is sufficient from your MLs then I'd try to cross very low to add clean deep bass (usually low volume as well) to what you have for a more grounded presentation. Good luck!

The REL t5x goes down to 32 hz and my Martin Logans go down to 34 hz. Will I notice the additional 2 hz of bass energy?

The short answer is yes you should, but probably not for the reasons you are thinking. The reason you will notice more extension is because the REL and any other powered sub will have a separate volume control. 

Your Martin-Logans like most every other quality speaker manufacturer is more than likely trying to achieve as flat a frequency response curve as they can. The problem is our ears do not perceive frequencies in a linear manner, so at average listening volumes the midrange is going to appear much more present than low bass. Depending on what type of music you listen to, you may actually want to have the low bass several db louder than the mid frequencies to achieve the sound you are looking for. Since all levels are fixed in the ML’s you would need some type of external eq. to make that change which may or may not work for you.

With a separate sub you now have control over the volume relationship between the low bass and mid/hi frequencies. The problem I see in your case with the low roll-off point and the passive radiator of your ML’s, is integrating a sub at a high enough crossover point and volume level with out some type of external crossover will probably be very difficult.

I would recommend something from the JL Audio “e” series and if you are willing to add an external crossover, then pretty much any sub should work.

There are hundreds of models of subs out there, and people get good results with many of them. Other people never get them set up and working as they'd hoped.

The key to getting good results is good integration. That means positioning, level matching, good crossovers, phase adjustment, and perhaps DSP to smooth the response. It rarely will work well just to plop the sub(s) down next to the main speakers and hope for the best.

I agree with those who say 2 subs will work better than 1. This smooths the in-room bass response, but again, that depends on positioning. As to setup. I’m impressed by the app provided with many of the SVS subs (e.g., SB-1000 Pro). The app lets you set level, phase, and up to 3 DSP points from the listening chair.

Since results depend so much on setup, my main recommendation is not to buy anything that can’t be returned if you don’t find it satisfactory.

I have 2 Rel t/5 in my small listening room and they are AWESOME!

https://www.parts-express.com/10-Wireless-Subwoofer-Package-with-Dayton-Audio-SUB-1000-300-5792

2-4 will work just fine. You'll be good to 25 or lower and cut the ML at 40-50.

You will enjoy FAST clearer BASS. 

That Mac has tone control, use it to get things right..

Room treatment, in a small room is a must... Thick floor to ceiling curtains work VERY well and help to dampen the room by opening and closing them. NOT just the curtain,. Windows and DOOR can be opened to release pressure too. Curtains will still dampen the opening..

1-400 watt 8 ohm plate amps get LOUD..  I use to hit the bump stops with a 12", 15", and a 15" passive drivers in 6 cf boxes all the time 125/250 watt plate amps. 18hz to 250 hz clear as could be..
VMPS RE- powered subs.. great value too.

My design was and still is very close.. I like using passives to really tune the blend the subs with the BASS. I use to use Mor-tite weather seal and pinch putty to get it JUST right.. (stays soft for 20 years)

NOW with DSP "perfect" is almost doable.. if you like it PERFECT.. :-)

I have a terrific Velodyne HGS10BG (10" woofer in black gloss) that I've had for years, but it has just sat, unused and unsold because it's extremely heavy and would be very expensive and a pain to ship.  It's a high-gain servo model that can keep up very well with the electrostatic panel.  I also have a pair of 18' AudioQuest woofer interconnects.  But I don't know how to give you my contact information; I'm afraid it would deleted by Audiogon.

I used this subwoofer with the Martin Logan Monoliths (one of their very first models), and it worked great.  The Monoliths were just that---Monolithic and HUGE!  I think the electrostatic panel was 4' by 2'.

After I sold the Monoliths, I had no use for the Velodyne, so it's just sat unused.  But it works great!

Look up the Martin Logan Monoliths online to see what they looked like.  Also look up the Velodyne HGS10.

If you know a way to enter contact information on Audiogon, let me know.  I would sell it all to you....for 1/2 of what I paid (or we could discuss).

I also have ML electrostatic speakers and have 2 ML Force 212 subs.  The subs make a significant positive impact. 

I second this. I have a pair of ML BalanceForce 210, a bit smaller than the 212, sounds fantastic with my Wilson Audio Yvette’s.

I have a pair of rel Ti7s with my Maggie 1.7is & they integrate seamlessly. Very fast & keep up the planer's speed. Never tried them with MLs, though. They make a world of difference in my system.

Like you I'm working with a small room 13'x11, which is less than ideal.  But I'm getting favorable results using 2 Bowers & Wilkins ASW608 8" subs.

I think this topic has been discussed in great detail on previous posts, but I'm suggesting at least 2 subs as minimum for 2 channel. My mains are Dynaudio Contour 20's which on their own have significant bass response.  The B&Ws just fill in the lower end, and as also discussed previously they are set up so you don't notice them. The effect on music  is just fuller and more realistic sound.

I have them positioned in front of the Dynaudio's and facing backwards; this was based on a suggestion from JS of Get Better Sound, and it really works for the small room!

Another note, I'm also using a 200w McIntosh; with outputs for 2 subs.

I have a pair of REL T7is with my Maggie 1.7is & they’re incredible. They’re very fast & integrate seamlessly with the speed of the planers. I also ha a T5i with my Vandersteen 1Cs & it works perfectly with them as well. FYI...I think the T5i has just been discontinued & replaced with a more expensive T5x model. Upscale Audio has the T5i closeout on sale now for $549.  I’ve not heard REL subs with ML speakers.

I am using the ML Dynamo 800X with my ML ESLs and with the built in Anthem Room Correction and numerous settings for low pass filter, type, phase, volume, listening modes, 20-30Hz level, etc.  It is a sealed sub woofer and should blend well with any ML ESL speaker.  They make larger in the 1100X and 1600X but in your small room 2 of any such as the 600X or 800X should work well.

Take a look at HSU research subs.  They are of fantastic performance for the money. 

Thank you all for your thoughts. 
I’m really liking the idea of the RELs. There are multiple dealers in my area that will allow me to get a listen. 

I’m not one to mess with two subs, especially in a smaller room. Bass, below 100-120 Hz appears non-directional. I did not say non-directional dogmatically. The mid-bass and midrange give the sense of directionality, so two subs for this purpose are not required. And with placement, integration, crossover, volume and phase, one is quite lovely. 
The key is proper room pressurization. 
I have a Rel T9/I and a medium room - exquisite.
look up the new T9 and check the extension very nice and very low for its size.  

I`m using 2  12" HGS Velodynes with my 3.6 Maggies the integration is outrageous, I also suggest looking into a integrated amp or tube preamp & SS Power amp combination in the near future.

I find myself in agreement with @jwillox . I moved from a pair of ML Descent i sub’s sporting the optional crossover cards with my ML CLX Anniversaries to a more centrally positioned single ML Balance Force 212 and preferred the ease with which a single source base extension integrated with the main speakers and room.

That said for 80% of my music predictions I switched the subs/s off as I prefered the more natural midrange of the CLX’s with their own integrated ESL base panels which measured down to a solid 46Hz -4db  in my room. 

I have a small room and also have ML electrostats. I have them paired with an older Velodyne DD15. Integrates very nicely. IME, I wouldn’t go with anything smaller than a 15. When my Velodyne finally gives up the ship, I’ll be replacing with a Rythmik F15 as it’s servo controlled much like my DD15. I’ve researched a lot into SVS. Great customer service but their subs don’t seem to be well-regarded for music. Geared more toward home theater.

kenrus, 

This might be what you are looking for and they have a 45 day trial plus free shipping!

https://www.svsound.com/products/3000-micro-subwoofer

All the best.

JD

Hsu Research, 18” Velodyne, or the “El Pipo” DIY sub ( this would be my choice”. 

@bdp24 

You got me interested! :-)

Which GR Research Kit do you use? The one with 1, 2 or 3x12" drivers per amp? How many in your room? How far away from the walls do you have them in your room?

I have a couple of Rythmik F12 in DIY sealed heavy boxes, with the same plate amp GR uses (A370PEQ), although with the aluminum driver. I've gone deep into DIY speakers and I'm running open baffles above the subs (65 Hz). I was thinking of eventually adding another pair of F12 to create a DBA, but maybe I get a couple of these plate amps and more drivers and have open baffle DBA...

Cool @lewinskih01! I chose to go with two woofers per side, in the less-common W-frame (most people go with the H-frame, including the Canadian woodworker who offers GR Research customers a great frame in flat pack form), which Siegfried Linkwitz also chose for the frame of his OB loudspeakers. For that reason I got the 8 ohm version of the GR Research woofer, rather than the 16 ohm.

Why? The Rythmik A370 plate amp puts out maximum power into a 4 ohm load (as do of course almost all solid state amps), but doesn’t like to see an impedance lower than that (few do!). A pair of the 8 ohm woofers are fine (in fact optimal), but three of them present too low an impedance to the amp. For that reason, if using three woofers per amp you MUST use the 16 ohm version. However, two of the 16 ohm---which produce a combined impedance of 8 ohms---doesn’t draw all the power out of the amp of which it is capable. Wasteful, as well as lower in maximum SPL capability.

I have the OB subs 5’ from the wall behind them, which makes sense since my loudspeakers---also dipoles---are the same. I have the two side-by-side, but that’s because I use 180 as the x/o frequency between sub and loudspeaker (unlike a normal sub, the OB plays up to 300Hz. It can therefore be used as a woofer with any loudspeaker whose midrange driver reaches down to 300.). One thing to know about the OB Sub: as it produces a null to either side of the frame, it MUST face the listening position if you want full impact at that location.

Though Rythmik’s Brian Ding was involved in the development of the OB sub (including creating the Dipole Cancellation Compensation Network---6dB an octave below 100Hz---he installs in A370 plate amps destined for OB usage), it is more Danny Richie’s baby. Brian found the OB sub to sound more "lean" than he cares for, without enough "weight". It is that weight that many dipole speaker enthusiasts/owners object to in "normal" subs. Each to his own!

In a small room just start with one and why not look at the ML subwoofers? 
Decent fair price and it is a small room.

Kenrus, it is a double edge sword. You will need two subwoofers of at least 12". Yes, I did see the size of your room. If you are going to spend money don't bunt. You need two 12"s or four 10"s or you are just adding a woofer on top of woofers. Getting them to sound right under the MLs will be a challenge from an analog perspective, relatively easy from a digital perspective. Digital bass management IMHO is the best method of integrating subwoofers. 

@lewinskih01
I have a dual opposing subs as a single sub. Like you I am interested in Rhythmik pair of speakers to make a DBA, possibly open baffle as well?
Something to consider after I've got more room treatment finished.

@bdp24
I'd like to know more about the differences with sealed and OB with the Rhythmik sub amp designs. I wish I could hear both to make a determination, but not likely to be anytime soon.

@rixthetrick: To read lots of discussions about the GR Research/Rythmik OB/Dipole Sub, head over to the GR Research Forum on AudioCircle. There are threads dedicated to the sub which contain info provided by GRR owner/designer Danny Richie, as well as guys who have built it. Once you have heard an OB woofer, sealed/ported are simply no longer good enough!

Rythmik's Brian Ding does not actively promote the OB Sub, though it is listed amongst the DIY/Custom models (not just the OB, but also sealed and ported subs.). On the Rythmik website, owner/designer Brian provides a LOT of info about the Rythmik line of subs, some of it very technical (Brian has a PHD, and is brilliant). On the website there is also a link to another Forum with a dedicated Rythmik section. Rythmik owners are passionate about their subs! 

SVS

@bdp24 - thanks.
I know oldhvymec loves his OB too.

@oldhvymec - have your well fed chickens started laying Emu eggs yet? They are large and dark green, thought I'd share that, might save you puzzling over it in the future if they do :-)

I'm a huge fan of my SVS PB2000. I've owned Velodyne and Monitor Audio subs. This SVS is in another league. House shaking low end, great control and presence. I enjoy the ability to use the phone app to really dial it in. For me it would be a no-brainer. 

I've owned Velodyne, SVS and RBH subs - and now have a JL F112 V2.  The JL is in a completely different league in my system.

My main listening room is 13’x9’. I run three HSU subs. To my ears,they work very well. 

Martin Logan makes push/pull subs (top of their line) that are fast and just right for your Martin speakers. -1 For Hsu or ANY brand that have drivers that face downward, passives are okay, but not desired in my world. 2¢

@bdp24 

Thanks for the perspective! I will do some digging at Audiocircle.

In my case my dipole (naked) 18" midbasses go from 65Hz to 275Hz. I agree there is some weight loss (vs a sealed 18") but I have not heard this level of articulation before. Large midbass, though!

I noticed you xo your GR Research subs at 180Hz. What's your view about how much difference it makes to have sealed vs OB subs below 70Hz? I'm sold on the advantages on dipole above that, but wonder if taking the sealed sub DBA below 65Hz wouldn't be the most practical approach and deliver the same sound quality.

@ewinskih01: Danny Richie uses a pair of OB subs in the front of his room and a pair of F12G's in the rear (in both his company's listening room and at hi-fi shows), the F12's in phase opposite that of the the OB's. I believe he uses 40Hz as the x/o frequency between OB and F12.

OB subs sound different from sealed and ported for a number of reasons. Not just because of their dipole SPL drop-off with listening distance characteristic, and not just because the woofers don't have an enclosure in which to produce resonances.

First, their dipole design produces a null on either side of the OB frame (for those who don't know, the waves from the front and rear wrap around the frame and meet in the middle of each side. Being in opposite phase, their combined output is zero---the two cancel each other). The result is that the sub---producing no output in the left-to-right plane, typically the room's width---does not energize the room's eigenmodes in that room dimension. Less "room boom"! 

Secondly, sealed and ported subs "pressurize" a room; the sub enclosure creates a separation between the interior of the enclosure and the air in the room in which it resides. When the woofer moves outward (in response to a positive signal), the air pressure in the room is increased (compressed); when the woofer moves inward (a negative signal, of course), the room's air pressure is deceased.

OB subs, in contrast, do NOT pressurize a room. The air on both the front and rear of the OB frame is vibrated by the woofer, but the room's air pressure is neither increased nor decreased. How could it be? The air pressure is moved around within the room, but that's all.

Some people like the sound/feeling of the pressurization of the room (Rythmik's Brian Ding, apparently). An OB in the front of the room with a sealed in the rear produces a compromise between the two---the lean/"taut" sound of the OB (optimal for blending with planar loudspeakers), the weight of the sealed. 

GRs OB servos are the cat meow. I use them about 60 hz down, and with MB columns phase plug tuned.
That is how I balance the weight of the bass. I like 80-280 or so..to be VERY fast.. I direct couple those drivers to BIG amps and use active XOs with full blown DSP multi xo points,  threshold, summation, on the fly correction and mic feed for OTF correction and testing..

Just so you know there is NO dampening when there is anything between the amp and the drivers.. That includes a passive XO.. NO DAMPENING.. No mater what you think.. ZERO.. My way it does.. just that simple. I'm not the only one either.. look around.. IF they will share..

I use to use VMPSs bass design, man were they easy for a passive design and DEEP bass. I still do when I need chest compressions..

They will do it..

GRs though.. just night and day how they work and pressure a room.
bdp24 couldn’t have said it better. When I coupled that system with MB columns.. I really got happy for the first time in a LONG time.. Man oh man does it work.. of course Planars and ribbons for the monitors sections.. again separate enclosures.. Lot of real estate though.. BUT you can actually get the sound perfect for your ears..

Where’s my transistor radio, go do a little sanding in the shop..
Clear coating plinths for the 124s.

Rel subs, in stereo, sized for your room.
Easy to adjust for various recordings and media, which is a requirement.
https://systems.audiogon.com/systems/8259The Time Machine doesn't lie.

Depends what your budget is suggest
Looking at Velodyne's new Deep Blue 15"
Or if budget allows DD15+

I happen to be one who (also) has a Rythmik F12-G paired with Maggie planars (MMGs).  Run through a Parasound P5 preamp and a B&K EX-442 Sonata (350 wpc @ 4 ohms) the sound is..............pleasing.

I highly recommend the Rythmik F12-G as a fast, musical sub.  The servo design those guys use is impressive.

Audiorusty may be on to something,  while I am in a similar situation as you, my Acoustat  Spectra 33 panels are a bit larger than your ML's , push out a bit more bass. The sub that came with the 33's is Crap. When listening to a bass heavy track,  those panels go down low, then I listen to something with a flatter curve and want more bottom. I have not pulled the trigger but I've been looking at the Schitt Loki Mini + . I've tried to be a Purest,  but with panel speakers and not so good recordings, sometimes you may need just a bit more. For $150 , I would look at this first before spending many times that amount looking for a good ServoSubs x 2...

Having run at least 10 different subs with my ML Summits I can safely say that the only subs I ever found to be fast and accurate enough for those speakers is the SVS SB 1000 in stereo. Don't waste your time and money on the rest of it I've already done the research and paid dearly for it.

Two Rels S/510