Need advice on adding subs

I’m looking for advice on adding subs to my system.

I listen primarily to small combo jazz and classical but I’m disappointed by the classical symphonic reproduction. I can only enjoy symphonic music on my headphones. Perhaps, I could improve symphonic on my main system by adding subs.

I don’t listen at high volume nor am I a bass fanatic. I just want the better sound. This is strictly 2 channel system. I have no interest in HT. I live in an apartment.

My system:

Balanced Power Technology BP-1 Conditioner
Toshiba lap top with JRiver feeding via crossover Ethernet to
Sonore Rendu
Wyred4Sound Dac-2
Warpspeed Optical Attenuator
First Watt J2 Output power 8 ohms30 watts 4 ohms15 watts

Reference DeCapo MM 2-way Monitors

The speakers are a simple 1st order high pass passive 3kHz x-over to the tweeter. I believe the woofer is designed to rolloff naturally at both ends of its band width.

I’m open to any ideas. Lets say up to $2000 budget.

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I just sold a wisdom SCS sub for $1800, which was about 60% less than retail. I actually traded it to a dealer at that value and I expect he would want no more than $2k tops for it.  (Eric Lang, Wired Audio, winter park FL, great guy, excellent service).

i used the wisdom sub with my Rockport Mira Monitors in a 2 channel only system.  I ran the monitors full range and dialed in the sub with its built in amp and crossover controls.  

The setup certainly added to the monitors. I liked to keep it dialed in to the point where it was hard to imagine if it was even on or off, until you actually flipped off the power on the sub.  That subtlety worked very well for me and added those very necessary lower octaves.

The wisdom was excellent.  I do not have a ton of comparison experience with subs, but I'd like to think I have pretty good ears, and I was very critical/skeptical/cautious when adding the sub.  Keeping the monitors sounding beautiful was an ultimate priority.

I ran a Bryston electronic crossover for a while, but in the end, preferred the sound when the Rockports ran full range.

Lastly, the SCS Sub has some convenient placement flexibility, and has a very different form factor than most subs, which added to its appeal.

good luck!

You don't need to spend that much. Take a look at these!
If you are going used, a pair of Vandy 2WQs would be a bit under your budget.  They are fast, tight and would match well with your speakers since they have a first order crossover as well.  When I had a pair, I set them up just like marktomars.  Dial them back so that you really can't tell that they are on, except when you turn them off.  
There is a good thread currently running elsewhere on the site, under the simple title "Subwoofers" (I think). Duke of AudioKinesis and BDP24, among others, have made some valuable contributions, and it is worth reading. Here’s the link:

It's a long thread, but worth the time to read through- some thoughtful stuff that I benefitted from. 
I'm not in love with the combo of deCapo and subwoofers.  

The deCapo is beautifully balanced as a stand-alone.  The presence thru treble is gently rolled off to balance the modest bass energy.  As a stand-alone monitor, it's really, really good and IMO one of the best values out there (which is why I bought mine).  When I added a subwoofer (for pretty much the same reasons stated in the OP), I loved the extra weight on the bottom end, but the sound as a whole went dull.  I tweaked it for a long time, but eventually moved on.

I think I'm one of the bigger subwoofer fans on this board and I'm surely one of the bigger deCapo fans, but the combo didn't work for me.  YMMV.
There is no "absolute set it and forget it" answer to subwoofer sound as there is a huge disparity of bass level in music.  I don't like digital room correction devices as they appear to be somebody else's ideas coming into my hifi zone (and my experience as a professional live sound mixer makes my tone ego enormous), so I simply turn the subs (2 RELs) up or down a little here and there…this is easy and works well for me and the room furnishings provide all the "treatment" necessary in my particular listening space.

$2000 will just cover the cost of the most unique, transparent, unboomy sub of which I am aware: The GR Research/Rythmik Audio OB/Dipole Sub. The catch is that it is not a ready-to-play, factory-finished product. But it's pretty easy to do, if one is sufficiently motivated.

1- You buy the DIY kit from GR Research or Rythmik Audio, the co-designers of the sub. It contains four 12" woofers (a pair for each of two subs) optimized for Open Baffle use by Danny Richie of GR, and a pair of Rythmik's dedicated plate amps (one for each sub, of course) featuring Servo-Feedback control of the woofers, along with a shelving circuit to compensate for the acoustic roll-off endemic to dipole designs. The Rythmik amp also features outstanding controls including adjustable cross-overs (frequencies and slopes), three levels of damping, 1-band PEQ, and, most importantly, a continuously-variable phase control (absolutely mandatory for integrating a sub with speakers. Do NOT buy a sub without it!). The kit is about $1500 including shipping.

2- You buy a pair of Open Baffle H-Frame flat packs from a woodworker who offers them on the GR Research AudioCircle Forum for around $500. Don't worry---I bought from him, he's very honest and trustworthy. The frames are sent unassembled, but are as easy to build as an Ikea bookcase (well, almost). Made of 1.5" MDF (!), they are a truly excellent design, and very non-resonant (unlike the W-frame design of Linkwitz). You then simply paint or veneer the frames to suit your taste and style. See the thread about them on the Forum for details. If this sounds like more than you want to deal with, you could have a cabinet shop assemble and finish them for you.

There was an OB/Dipole sub offered by Gradient in the 80's, for use with the Quad 63 ESL's (reviewed by REG in TAS). This is similar in concept, but much more advanced in execution. Higher quality drivers, with Direct Servo-Feedback (patented by Brian Ding of Rythmik) control of their motion. State of The Art in subwoofers!

Thank you all for the help.
There is a good thread currently running elsewhere on the site, under the simple title "Subwoofers" (I think). Duke of AudioKinesis and BDP24, among others, have made some valuable contributions, and it is worth reading. Here’s the link:
That's a great thread. I had looked at that thread earlier and came away from it with some insights and some confusion.  My takeaway from that thread is this:

A sealed box gives the most musical and dynamic bass.  Using two subs instead one would let me crossover at a higher frequency.

That's why I was looking at a pair of Rythmik F12 or F12G. 

One thing that confuses me about that thread.  There appears to be a disagreement about aluminum vs paper driver.  That's the difference between the F12 and the F12G.  Can anyone clarify this for me?
Hello Martyki
Could you tell me more about the subs you used with the DeCapo

The deCapo is beautifully balanced as a stand-alone.  The presence thru treble is gently rolled off to balance the modest bass energy.  As a stand-alone monitor, it's really, really good and IMO one of the best values out there (which is why I bought mine).  When I added a subwoofer (for pretty much the same reasons stated in the OP), I loved the extra weight on the bottom end, but the sound as a whole went dull.  I tweaked it for a long time, but eventually moved on.  
  I agree the Decapo is a great speaker. Chamber music and jazz are great. But, I can't stand to listen to symphonic music on these speakers.
Hi BDP24
Wow. That's spooky.  I was looking at the Rythmik web site and the email notification with your post poped up on my screen.

You buy the DIY kit from GR Research or Rythmik Audio, the co-designers of the sub. It contains four 12" woofers (a pair for each of two subs) optimized for Open Baffle
Ok.  Open baffle? Is this a speaker with out a box?  Because that sounds like the opposite of everything I've read about subwoofers.  That is, that a closed box provides the best bass sound quality.  Ported boxes compromise sound quality to improve volume.

Unfortunately, this was some years ago and I'm not 100% certain of my timeline.  Over the last decade plus, I've used both Velodyne SPL subs and (the far superior, IMO) Rythmik 12" subs extensively (among others, less extensively) with many different speakers.  I still own both sets of subs, tho the SPLs have been relegated to non-critical uses.  I may have well tried both with the deCapo, but I can't swear to it.

In any case, I don't think it was the choice of subwoofer that did in the combo.  IMO, subwoofers work best with neutral to somewhat bright monitors.  I'd call the deCapo neutral to somewhat warm in voicing.

YMMV, but I eventually concluded that the deCapo works better as a stand-alone.  IMO there are numerous monitors out there that work better with subs .... probably because they weren't as skillfully voiced to stand alone.  Just MHO.
cjk: I think the take away re paper v aluminum is that the paper will sound more natural if you are solely using it for music and/or want to x over higher. I bought one that was delivered Friday as part of an experiment- a paper coned 12 in the ebony gloss finish using the xlr’d version amp.
The takeaway, as far as I’m concerned--others may have different views- is that multiple woofers even out the room response.
I have experimented with subwoofers for decades in my two channel audio and was never happy- trying to match them with Quad electrostats. Not only have the subwoofers improved, i think in part due to home theatre and car audio (JL anybody?), but it seems there is renewed interest in and thinking about high quality sub-woof’ing for two channel audio. A lot of what Duke wrote in that thread made sense to me in terms of "apparent" speed- sensitivity to frequency and volume, rather than just timing (if I’m remembering it right, it wasn’t leading edge timing that’s the issue, but ’stopping,’ among other things).
I’m also experimenting with DSP and a bigger old woofer- I have a bunch of Velodynes from the old days- an 18" (size of a coffin) and a 15"- both are well past their shelf life, but I DSP’d the 15" and am x’ing it over very low~ 45 hz. The Rhythmik is running without DSP, placed midwall on the opposite side in a corner-and crossed over a little higher-it’s a weird room. I got the levels matched at the listening position and have only enough loudness that they blend into the multiple woofers in my horn array. With some fiddling around-a few crude measurements, and some listening, moving, and listening, they seem to gel nicely and add a nice further dimension to my listening. I don’t listen particularly loud to begin with, but augmenting the bass--running as a parallel system, no high pass to my main system--has given the system more gravity and spaciousness, more music at relatively sane levels.
The moral, I think, is that these things can work, not just because the technology is better than it was 20 years ago, but because the strategies for placement and dealing with room interactions are more effective.
PS: I can't speak to the open baffle or dipole, one of the others can address. I know that using a dipole like a Maggie was one thing HP used to tout with the Crosby Quad back in the day, but I never tried it. A DIY build makes sense to me even if you have to get some help from a competent cabinet maker. Good luck and have fun. I certainly am, and it has added joy to an already good system.

cjk---The Rythmik 12" that whart just received is the F12G (G for GR Research) and it has, as he mentioned, a paper cone. The exact same sub is available with an aluminum coned-woofer instead, and that is the plain ol' F12. Danny Richie of GR Research (who designed the paper-coned woofer) feels that paper has a couple of advantages over aluminum: 1- greater resolution and transparency; 2- a more natural timbre and tonality; 3- lower mass and energy storage; and 4- can be crossed over at a higher frequency than can aluminum. Brian Ding of Rythmik Audio (designer of the aluminum-coned version of the woofer) recommends the aluminum-coned F12 for applications where higher volumes will be required (HT, bass heavy material at high SPL). That is because aluminum makes for a stiffer cone, less subject to cone breakup when driven hard. Other than the cone material, the subs are identical. One Rythmik customer (DonH50) just added two more F12's to his system (for a total of four), his speakers being Magnepan MG3A's, and is very pleased with the F12's. If you listen to acoustic music at moderate volumes, or want to x/o at higher than 80Hz, go with the paper. If you listen at high volume to bass heavy material, go aluminum. The difference is subtle, and either will work great with your speakers.

I understand your confusion regarding the Open Baffle nature of the Dipole Sub. I had never heard of the concept and design (though it was not unheard of; the Finnish company Gradient offered an OB/Dipole sub designed and marketed specifically for the Quad 63 speaker a couple of decades back) until I started doing some deep research into subs to mate with perhaps the hardest speaker in the world to add subs to: the original Quad ESL. Open baffle speakers and subs have a cult of enthusiasts who feel that putting a dynamic driver in a sealed or ported box leads to, well, boxy sound! Subs would seem to be a poor application of the OB concept, as the front-to-back cancellation (endemic to OB design) at subwoofer frequencies is a real problem, one leading to loss of output as frequency descends. But OB enthusiasts are guys who find the sound of sealed and ported-box subs too fat, thick, heavy, and boomy. Plus, they "load" the room in a way OB's don't, making the room itself a giant speaker enclosure. More of the room's modes are excited by boxed vs. OB subs, and the result is the "slow" sound of most subs, to use the parlance of the general public!

Cones can be used in free air (rather than in a sealed or ported box), but have to have their electrical and acoustical characteristics tailored specifically for OB use. Danny Richie of GR Research is a long-time designer of drivers, cross-overs, and DIY speakers and subs (including some OB's), and has his driver designs manufactured to his specifications. He offers DIY kits containing those drivers, the x/o component parts, and diagrams for building the open baffle or box within which the speaker or sub parts are installed.

When Danny heard there was a fellow Texas-located designer who had a new patented Servo-Feedback subwoofer design, he envisioned combining it with the OB/Dipole sub design, and contacted Rythmik Audio's Brian Ding in Austin, Texas. The two put their big brains together, and created the world's first and only only Open Baffle/ Dipole Servo-Feedback Subwoofer! By the way, the sub is used in the remarkable $20,000 Serenity Acoustics Super-7 loudspeaker, as well as the GR Research Super-V, recipient of "Best Bass At The Show" award several years running at RMAF. The best bass reproduction available at any price. Not the most output (owing to the nature of it's OB design, and it's "mere" dual 12"-drivers)---for that you want to go with 18" drivers, massive ported enclosures, and class-D pro amps. But for highest sound QUALITY, this is IT!

But the OB/Dipole sub won't be for everyone. It needs to be out in the room (a minimum of 3' from the wall behind it, as with all dipoles), it needs to face you, and it won't have the sound some listeners expect from a sub, one that lets you know there is unquestionably a sub in the system. The OB disappears, it's presence undetectable except that your main speakers now sound like their woofers just gained an octave or more of response at the bottom, the speakers now sounding more transparent, less strained, and playing louder and cleaner. But the standard Rythmik F12 or F12G (or F15, with an aluminum 15" driver, or F25, with dual 15's!) will give you that too, just not with quite the utter transparency of the OB. NO other sub will give you that, but the Rythmik's come closest. They have Brian Ding's Servo-Feedback system for controlling the operation of the woofer, a very high quality driver, amp, and enclosure, and the best controls available in any sub on the market, to integrate the sub seamlessly with any speaker. Sterling Sound in NYC, famous for their world-class LP mastering, has a dozen of them in their monitoring systems. They could buy any subs they choose, and they chose Rythmik.

Oh, one (I promise ;-) other thing. The Rythmik Sub is what speaker builder Jim Salk builds in to some of his models. He also offers the Rythmik Sub in his own designed and built enclosure, featuring greater internal volume (for increased efficiency) and more robust bracing (for more non-resonant sound). His finishes are beautiful real wood, much nicer than the Rythmiks (except the Piano Black Rythmik whart got---it's real nice).
not going to write a book,  check out jl audio fathom
My advice! Velodyne optimum series! Why!! Built in room equalizer! Volume control for leveling and blending with your system! Subs are for depth and warmth! Not to rattle Windows! If 250 hzto 20hz doesn't sound like it eminates from your other speakers, your towers, it's just not high end reproduction! Subs should be adjusted to room acoustics and blending volume! My system is krell, Bryston, Psb imagine t3 speakers! Velodyne optimum 12! Total system investment, just short of 60k! Velodyne optimum 12, around 1300.00 ! Rel the best! Rel not volume controlled ! Rel at 2300 to 2500! 

Cjk5933: Pennsy here! Read my posts! My sub advice came directly from two techs at Krell electronics! If you are a higher flier than my 60k system and 5 figure electronic units, well i understand!
My B&W 803's really opened up in my main room (25x235, most of my house). Since I had experimented with various woofers for my prior electrostatics, I had a baseline.
Instead of a generic sub amp, I use a matching amp and preamp for my subs. This is not necessary, but does allow me to place the sub cabinets in a time aligned fashion with my mains. It also allows a separate volume control with no crossover issues, because, I use a mechanical, rather than an electronic crossover, many of which I still have. It consists of foam in the center of the speaker cover cloth and beat crossovers designed for my drivers, as well as Thiel sub crossover I still have., and several others which as good but not as good as my reversed cone of foam. 
    On most LP's, FM, some CDs and especially XM, it really helps fill out the sound.
Th  sub system is off for most small combos. 

I want to thank everyone again for the help. Sorry for the late response. It's been a busy week at work.

As often happens when I post a question here, the answers expose me to the complexity of audio reproduction.

The other thread recommended some authors like Toole. I think I'm going to do some more reading on acoustics to better understand the nature of bass reproduction before I commit to a purchase.


  You buy the DIY kit from GR Research or Rythmik Audio, the co-designers of the sub. It contains four 12" woofers (a pair for each of two subs) optimized for Open Baffle

 I have some rudimentary DIY skills so I could probably manage a speaker assembly. I'm a bit cautious about the open baffle. I've noticed that a lot of people are experimenting with these type of speakers. But, audio has a history of technology fads that are initially celebrated but ultimately disappoint.   You have inspired me to get a little more serious about understanding acoustics. I think I need to study more before I start sinking even more money into audio.

JBL 305.
Post removed 

I understand your trepidation regarding a new-to-you design (open baffle subs), cjk. But consider this: More than a few people consider one particular type of loudspeaker still the best overall of any yet devised: The Planar, one type of OB; Electrostatic, Magnetic-Planar, Ribbon. They have been on the market since the 1950’s, hardly a fad! OB subs are nothing new, but have long presented unique problems for designers and users, and have never become common, remaining a hardcore OB enthusiast cult item. It was Danny Richie’s vision of mating the OB sub principal with Brian Ding’s Rythmik Servo-Feedback design that has allowed the two gentlemen to solve many of the OB Sub’s inherent weaknesses (lack of output, low-frequency dipole cancellation, size), and create the best musical bass reproducer currently available.

Sound quality fanatics, particularly in Asia, have been using Magneplanar Tympani bass panels as woofers since Harry Pearson came up with the idea in the 80’s. The huge Magnetic-Planar drivers provide a quality of bass reproduction unlike that of any cone woofer. If you’ve ever heard a Tympani speaker, you know what I mean. Taut, transparent, with no-overhang or boom. The Tympani’s reproduce the sound of low register piano strings, acoustic bass and cello strings, and bass drum heads like nothing else! I bought a pair of Tympani T-IV’s specifically for use as woofers with my old Quads, finding no boxed sub to blend seamlessly with them, a common opinion amongst Quad owners. The GR Research/Rythmik OB/Dipole Sub has replaced the T-IV’s in my system. It’s that good!

But it’s not appropriate for every listener, system, and/or room. For those people, there is the Rythmik Sub, the next best thing. Call the guys at Sterling Sound and ask them for their opinion of the dozen F15’s in their mastering monitor systems. Brian offers 8", 12", and 15" models in both sealed and ported enclosures. Later this year there will be the new 18" model, at the request of Home Theater aficionados who appreciate the sound QUALITY of Rythmik subs, but want the output of the "monster" subs popular with the HT crowd.