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Published Reviews Customer Feedback DS12 with Linkwitz Transform circuit in a less than 2cu ft sealed box enclosure (from Brian B) "...... I think it sounds excellent! Very tight and articulate with great extension! I'm thrilled with the outcome. If you could some how get a 15" driver in your lineup I'd definitely stick with getting the drivers from you. This 12" is a real winner!" DS12-LT-A250 circuit in 2.5 cu ft sealed box enclosure (from Kent B) Brian, A370-SE (from Danlaudionut) The A370-Special
Edition is an awesome unit !!! Hooked to my HiVi D10G subwoofer
in a sand damped 3 cubic foot ported enclosure. It's very musical
with nice deep and tight bass. It does take some hours to breakin
though. Since the crossover is ~180 Hz it needed to be musical. Dual DS12-sealed DirectServo kit (from Darrin C.) http://bass.consumes.us Darin has written a wonderful review and host it on his own web site. Please check out: http://bass.consumes.us DS12 sealed box (from Eli B.) After building
a nice strong sealed box (1 1/2" thick mdf, internally crossbraced)
and installing your DS12 woofer and amp set, I have been DS15 in 3cu ft sealed box (from Dennis J.) I am just about
done with my Rythmik 15" and throught I would send you a picture.
I still have to finish the grill but other than that it is done
and sounds fantastic. I also have a Paradigm Servo 15 V1 sub which
you can see sitting next to the DS15 in one of the pics. From the
standpoint of excursion, the rythmik has about 3-4 mm more excursion
and similar power (370 vs 400 watts). The paradigm is one of the
best sounding and most musical subs I have ever heard but is somewhat
limited in output because of the very aggressive limiter they put
in this version. From an output perspective the Rythmik plays at
least 3-5 db louder. I haven't really explored the limits of Rythmik
yet but hope to in the next few days. The Rythmik sounds slightly
different but is every bit as tight and refined as the Paradigm...and
of course 1/4 the price (not counting the cabinet)
Kind regards, DS12 sealed box (from George P.) Correspondence 1: Have been buildiing a Chinese style cabinet for the subwoofer. Will start putting a finish on tomorrow and will install woofer Friday. Waiting for Chinese brass hardware for the front.Cabinet is 3/4 inch mdf with 3/4 inch solid Cherry wood over it. It is built like a tank - can hardly lift it. I'll send you a picture of it when done. I think you will like it.
Correspondence
2: I have the subwoofer working and it sounds great. DS12VC in 1.5 cu ft sealed box (from Ian W.) When I first decided that I wanted to take the plunge into high end audio, I read reviews, but being always a skeptic (and realizing that everyone has different preferences) I went and auditioned as well, and fell in love with the sound of Martin Logans. I bought a used pair of Quest Zs from a friend who was buying the new $10k summits, and was instantly enthralled. For Jazz and vocals, I had heard nothing like them. A wonderful, detailed, ethereal sound that drew me into the music. As I played other types of music, however, rock/rap/pop, I percieved a lacking in the bass/midbass region being covered by the woofer. I decided to try to integrate a midbass array and a sub, in order to fill this perceived deficiency. Being on a budget, I decided to make the array myself. Having completed this, a friend loaned me a $500 12" sub he had lying around. The brand will go unmentioned, but it was of the standard commercial variety for that price point, and ported. I integrated the sub with the system and balanced the level to match the rest of the system...but it just sounded...wrong. Boomy, bloated, one note bass, it just didn't mate at all with the panels. I was hoping it was the sub, but was somewhat fearful that the line array I had built could be to blame as well. Having read for over a year about the success people have had with the rythmik subs in music systems, but always skeptical. I decided to build my own box, and give the kit a try. I was enthusiastic, but not expecting to be overwhelmed. I made the cabinet out of double thick 3/4" mdf, with a triple thick baffle, and then veneered it (first time veneering!) with cherry. I then stained it and coated it with polyurethane...it turned out pretty nicely I think. When the kit (the DS12-CV Servo kit) arrived a couple of days later, I took a moment to admire the build quality and amp...and then assembled the sub. I placed it next to my array (not ideal positioning perhaps...but I just wanted to hear it!) and attached it, with an 80Hz crossover point, set to the 14HZ/High Dampening settings. I put on a piece of music, sat in my listening position, and WOW! It was a revelation. My first impression was "is the sub on?," because the imaging was so incredibly improved over the prior sub. I looked over at the sub, and saw the cone moving...but there was no indication of any sound coming from it whatsoever. It matched beautifully with the soundstaging and imaging of the panels (which is quite impressive.) Equally as well, it kept up perfectly with the finesse and detail from the panels, with none of the delayed resonance that I've heard from lesser subs in the past. I had a giant grin across my face, as I popped in CD after CD of ALL genres (even the ones I had said "well, martin logans just aren't good at playing this") and was amazed at the result. I had achieved what I had set out to, and much much more, and the key piece of that was the rythmik sub. My friend with the Summits came over to listen as well, and was equally as floored. The improvements were monumental. I've heard the Martin Logan subs, and the depth and descent are both great subs (that use servo technology as well) but I would be lying if I said that I thought they sounded any better than my rythmik...and they are at a much higher price point. I couldn't be happier with how this turned out, and I can very honestly say that I think my stereo now equals or bests many others that cost much much more. The upgrade bug that bites so often in this hobby is gone from me (unless it is to add another rythmik!) and I am enjoying my music collection more than ever! On movies, at first, I was a little bit disappointed, because I was used to hearing big one note bass reverberate during a big bass hit. The more I listened, however, the more and more I appreciated what the sub was doing. It made the entire movie watching experience more engaging...as things just sounded more realistic. It's no longer a matter of listening to a movie to hear "oh listen to the sub on this part" as can be done with other "big" subs. It's WOW, this whole movie just sounds great. I've been spending a lot more time movie watching lately as well! "Chronicles of Riddick," one of my favorite action movies, has many places that sound much much better now, especially during parts where energy weapons are being fired, as there's an awesome sensation that I've never felt before, and I've watched this movie many times (including in the theater). The only way i could be happier with the sub is if I had 2 (which I will at some point in the future-the box is already built!) As an aside, I accidentally gave a wrong(old) address through paypal, and contacted Brian to change it. He was incredibily responsive and put in a lot of time and energy getting the address changed with fedex and following up with both them and me. Incredible customer service. Thank you Brian, for such an amazing product, and equally amazing customer service.
DS12-sealed DirectServo kit (Rob, excerpt from AVSforum) In my room i've had a total of 4 subwoofers. 3 were sealed DIY projects, and the 4th is a small Velodyne dps-10. Of all 3 of my sealed DIY projects (Avalanche 15, Tumult 15d2, Rythmik servo ds12tc) the Rythmik is the indisputable sound quality champ. IDW, you will be pleasantly surprised with the capabilities of the Rythmik kit. DS15-sealed DirectServo kit (from Eric H.) I just wanted
to let you know that the sub has really opened up since our last
correspondence. Actually, one afternoon of fairly robust music made
the difference. I now have plenty of headroom at -5 on the sub pre-out.
The sub sounds great, goes DEEP like my PB12/Plus2 did, but is
much more defined and musical. It doesn't have the SPL of the
twin SVS, but it has more than enough for me. And this while I haven't
even started to eq it. Thanks for your help, and thanks for making
servo technology available to us DIYers. (....You're helping
people get very high quality bass in their homes for a price that
they can justify (get past the wife!)). DS12-sealed DirectServo kit (from Randy B.) Brian,
DS12-sealed DirectServo kit (from Dave G. in MI) Hi Brian, Thanks for the note. See the attached photo's. I am very satisfied with the performance of your servo sub. It quite easily beat anything I have tried before. It easily reaches 20hz. in my room and with the Velodyne SMS-1 I can achieve a frequency response with-in less than +/- 3db from 20 to 80hz. I have never heard bass response this tight and tuneful before, you have a great product. I will probably be ordering another sub after the first of the year to re-do the upstairs home theater system. The room size is the same as down stairs but with a very high cathedral ceiling so I am thinking I will need the 15" driver at a minimum or (2) of the 12" drivers. Have a great Christmas. --Regards--------Dave
DS12-sealed DirectServo kit (Pauly, excerpt from Audio Circle forum) I love my stereo pair of Rythmik DS12 subs.In the past I have built several ported subs but was never happy with the boominess of them. No matter how hard I tried to tune and place them properly. After listening to dozens of commercial subs at shops and friends houses, the Rythmik may be the most musical subs I have ever heard. Very fast, clean and tight. 118 lbs. each , the grills were originally 1.5" from the baffle and at higher volume the surround would hit them . So they were moved to be 2.25" from the baffle. I don't have 1000's of dollars to spend on subs ....but with these I feel like I have 1000's of dollars worth of subs. BTW, Brian Ding was a pleasure to deal with. He answered all of my emails promptly, shipping was fast, and they were packaged very well.
DS12-sealed DirectServo kit (from Larry K.) Hi Brian- Here are some photos of my project. (I reuse the PSB cabinet, which had 2 ports and a longer opening for the original 90 watt amp.) I had to fill in the ports and the top part of the amp opening, chisel out the inner enclosure for the amp, and remove the middle part of the original top to bottom brace.-After adding .5" and .75" wood inside the cabinet to strengthen it for your 20 lb. woofer, I used an aperiodic vent to make up for the lost air space. I also lined it with vinyl dampening sheets and ground the plywood between the T-nuts to improve air flow.Black cone feet were added after these photos were taken. The completed subwoofer now weighs 76 pounds! While playing a new age CD with low frequencies, I heard windows rattling in the bedroom next to my living room! These were below audible range but could be felt at a low volume. .......I like the sound of your new amp and driver. It is doing a better job than the 4 10" woofers in my main speakers.
DS12-sealed DirectServo kit (from Dale I.) Brian, DS12-sealed DirectServo kit (from Geoff S. in NZ) I have mostly completed building of my box for the servo kit 12inch that I bought from yourself, and I am very impressed, it seems to have the benefits that I gained when I borrowed my friends REL (with my Wilson Benesch Act 1's). DS12-sealed DirectServo kit (from Chris B.) I am amazed
you can sell this kit at that low of a price! This subwoofer has
good bass, wait, scary bass when you put it up. I find halfway on
the gain to be more than appropriate, anything higher is insane
in my room. This subwoofer playing music is a whole new experience
for me. The bass is not the muddy one-note bass where everything
just sounds like a loud boom, it blends so well with any speaker
I match it with. PS: I finally was able to run the Rythmik through some sweeps and measure the frequency response with a calibrated microphone, calibrated SPL meter, and RoomEQWizard. Here are the nearfield meaurements @85db for the different extension settings (all measurements were done at high damping) and the inroom response @75db from 2 meters away. I was extremely impressed by the results. In-room response 14hz, hi damping (no PEQ), 2m away
Nearfield, 14hz high damping
Nearfield, 20hz high damping
Nearfield, 28hz high damping
DS12-sealed DirectServo kit (from Linn T.) Brian, I finally got them finished yesterday. WOW! I went overboard in the cabinets and was a little worried when I fired up the first unit, it was very dull sounding. I lined the insides of the 1 1/2 inch thick cabinets with Parts Express Sonic Barrier. It is a combination foam and limp barrier product. I also cross braced the walls and attached some open cell foam between the driver and amp to absorb any sound reflected off the amp. The boxes sound very dead when rapped with knuckles and it was weird to hear sound die when I stuck my head in the box when I was working on them. Any ways, we ran some errands and left the speaker on to break in. Big difference. The units now have 8-10 hours on them and I am hearing detail in the low frequencies on CDs I did not know existed. I have been able to set my main speakers to small and shift more of the bass to the subs and this has improved the sound from the mains (Magnepan MMGs). I have not tweaked them alot yet to get a perfect match, but they sound pretty good now. I know we are getting lower frequencies than with the Velodyne fs-1500. We had things vibrating in our kitchen that had never moved before, even at louder volumes. My wife is very happy with the sound and that is always a good thing. She thinks they are worth the money and mess I have made putting everything together. A very satisfied customer. Thanks for everything. Linn DS12 sealed DirectServo kit (from Virgil J.) From a post at AVS forum: "I have a Rythmik audio servo sub paired with my MMGs and it sounds fantastic. I have analyzed my room curve on SMAART and the MMGs roll off pretty quickly around 100hz which is a little high for my taste, but the servo sub sounds good up that high and is still very responsive. I have it low passed at 110hz. Being a servo sub, it is very accurate. If the music is mixed with very little bass emphasis it will sound that way, if mixed with a big bottom end then the sub shakes the walls. This is different for me from other non servos I have had in the past where I can tweek them to output a certain db regardless of the material I am playing. I tuned my servo using pink noise at a 90db level and that is pretty loud for MMGs in my living room, as they are not a high SPL speaker. Rhythmik would be a little more than your budget and you would have to build your own box or buy one from Brian (owner of Rhythmik). I would suggest a sealed box what ever route you go, as it will respond quicker and give a flatter frequency response."
DS12 sealed DirectServo kit (from HI) Hi Brain J.L. DS12-sealed DirectServo kit (from J. B.)
Hello Brian, I have finally finished the cabinet for the DS12-sealed, and I just have to say WOW. Over the last several years I have been searching for a sub that would complement my 2 channel setup. In that time I have purchased several commercial subs (HSU, Paradigm, Yamaha etc.) and built two others. The first was a Dayton TitanicIII that I put in a 2.2F^3 cabinet, and the second was a Dayton DVC in a 2.5f^3 sonotube. Both of these subs performed quite well, but I felt I could do better. At about this time I heard of your company and decided to give you a try. To make a long story short, I do not believe I have ever had this level of bass definition before. No BOOM, no overhang, just well defined musical notes and harmonics. Once again thank you for a fantastic product and great customer service. DS12-sealed DirectServo kit (from Peter M.)
Just a note
and a few Pics---the subwoofer is truly excellent, tactile and
clean with no blurring of the bass line. The shockwave from
the cannon shots in Telarc's 1812 overture broke two windows and
killed a deer in the meadow outside! (Just kidding--but the sound
was awesome!) DS12-sealed DirectServo kit (from AJ)
Hi Brian, Can you believe it's taken me this long to get anything (somewhat) done! I attached a couple pics of what i did with your subs. One is built into a bookshelf case used to store DVDs,etc. Thats upstairs in the theater. Works great with my Infinity speakers. Fills out the bottom end nicely, crossed @ 70hz since my Infinity center is fairly large - 6.5x2 woofers. Hard to localize when crossed that low. I have gotten it to bottom on a few movies (Shrek2,etc), but overall I'm quite pleased. The other is used with a pair of self built Linkwitz Orion type speakers. I dont know if you are familiar with this design but they are the best speakers I have heard myself. I have audiophile friends with some very expensive Electrostatics as well as boxed speakers, plus I visit the high end stores here in town for reference. I use your sub in my music system to augment the lowest freq <35hz to limit the excursion of the dipole subs of my main speakers. It's probably overkill, but again I have strained my Orions low end on several classical and jazz CDs, so I think it worth it. Overall I'm happy with your product and have recommended them to anyone who will listen. Thanks again Sincerely, AJ Reply: One can bottom out the driver if the enclosure is larger than what is recommended. In addition, there is an inevitable unit-to-unit variation which can cause some units to be more efficient (that is, larger Vas), and therefore bottoming of these drivers. In this case, we recommend reducing the enclosure volume using 2x4 wood blocks.
DS12-sealed DirectServo kit (from Rolf H.)
Brian, I had the chance to compare the new servo kit, with the aluminum driver, to the old kit over the weekend. Both subwoofer enclosures are identical except for the choice of wood for the legs and I moved the position of the amp down 3/4" of an inch on the second sub to make it easier to mount the amp between the "legs". The cabinets are made from 1" HDF with four internal cross braces. The top and bottom is reinforced with 3/4" birch plywood. With the solid wood accent piece this makes the total thickness of the top 2 1/8" thick! The sub on the left is Sapeli and Santos Rosewood. The sub on the right is Sapeli and Quilted Birdseye Maple. The inside of the subs are lined with acoustic batting. The amplifier is inset flush and the woofer is inset 3/8". The total weight if the finished sub is about 120 lbs. They are finished with 12 coats of semi-gloss poly-acrylic (sanded between each coat, of course). The subs sit on 1 3/8" heavy duty spikes. Now as far as the difference in sound between the old and new kits goes, they are very similar. I used test tones from 250 to 20 Hz to test frequency response. The old driver is a little bit more efficient (ie - a little bit more output). The new driver is a little bit more controlled (damped?) at 20 Hz. I don't think that anybody will be able to tell the difference between the two subs sound unless they are placed side by side. However, there is a difference of about 2db in efficiency between the two. I prefer the sound of the old kit for movies/home Theater and the new kit for music. Of course, I'm really splitting hairs here. The sound of both subs are incredible and you will be hard pressed to find anything comparable for less than $3000.00. Considering I spent about an average of $800 each to build them, I consider them to be a true bargain. Thanks again, Reply: The efficiency that Rolf refered to was more on sensitivity than the efficiency. We have since increased the gain of the preamp stage so that the sensitivity in the new kits matches the previous version of kits. Also we have changed the low damping setting to Q=1.3 (from 0.9 previously) to provide a wider range of damping control. -Brian DS12-sealed DirectServo kit (from Rob in Ohio) Hi guys. My name is Rob From Ohio. I have one of your servo combo that I got from a friend of mine-Ron D.. I built the enclosure myself out of one inch MDF and sealed with epoxy in and out. I finished it with topcoat auto enamel and buffed it to a high gloss shine. (I use to work in a bodyshop). The end result was worth the time. This is the cleanest, tightest, and most accurate bass I've ever experienced. I have it running with my MTM Focal polyglass towers. The sound is great! .........Thanks Rob
DS12-sealed DirectServo kit (from Michel M. in Netherlands ) Hello Brian, Follow-up Brian, DS12-sealed DirectServo kit (from Ken A.)
The finished box is a 19.75" cube, however the speaker baffle (bottom) and the opposite wall (top) were reinforced with an additional layer of 1/2" MDF so their total thickness is 1.625" The interior dimensions therefore are 17.5" x 17.5" x 16.5", which comes out to about 2.9 cu ft, and the bracing, projection of the speaker and amp, etc. added up to about 0.6 cu ft, so the effective interior volume is 2.3 cu ft. Additional construction details: There is a main horizontal brace of 1.25" MDF and four 1/2" braces, two above and two below the main brace. The lower two were cut to allow room for the speaker. I cut a pattern of holes (1" - 5" dia.) in all the braces to optimize the internal volume and airflow; I then rounded over all the edges with a 3/8" bit so the interior of the box would contain no acute angles. When I assembled the box I also made sure to place the braces so the vent holes in one brace were offset from the holes in the adjacent brace. The braces were rabbited into each other and the box sides, and glued to each other and the box sides with polyurethane glue. I then sealed all the internal surfaces with two coats of marine varnish, and lined the interior box walls with 1" dense acoustic foam. The box sides were attached with polyurethane glue and self-drilling pocket hole screws. All screw holes were countersunk and later filled with Bondo wood filler and sanded smooth. The outside surfaces were then sealed with diluted yellow carpenters glue and finished with double thickness maple veneer using contact cement. The veneer was later stained to match the existing woodwork (gumwood) in the family room using Bartleys Gel Stain, and varnished with two coats of Bartleys Gel Varnish (satin). After the first coat of varnish I went over the edges with some mineral spirits, so the end result has a "worn" look, like a piece of old furniture. Before installing the components the cavity was loosely packed with polyfill. The finished sub weighs approx. 175 lbs., so I attached four casters to the bottom which allows it to be rolled around and also elevates the box about 4". My goal was to make the box as "dead" as possible, and I think I accomplished that goal. At peak listening levels (110-115 dB), I cannot detect a buzz, vibration, resonance or any aberrant sounds coming from the speaker. Other than the waves of bass relentlessly pounding me, the only other way that I can tell the sub is on is by putting my hand underneath it to feel the air current, or placing my hand on the top of the box where I can detect a slight vibration. The output is extremely tight, the word that comes to mind is "transparent" since when I am listening to music I cannot detect that I am listening to a speaker. I am using a Behringer parametric EQ to even out the in-room response, because my room and sub location were pre-defined and ultimately not very optimal. I really need another sub to correct the room response, but there's no way I am going to relive the experience of making this beast (and after the first experience I think my wife would kill me if I even mentioned the idea of building another sub). At peak volume, the initial measured output at 35 Hz is about 115 dB, 105 dB at 20 Hz and approx. 95-97 dB at 18 Hz; it drops off steeply below 17 Hz. I don't know the upper limit since I have my amp's crossover set at 80 Hz. Like I said before, I need to re-EQ the box since it has broken in, and once I have a few spare moments I will plot out a room curve and send it to you. Overall, I love the sub, and the entire experience of designing and constructing it was very worthwhile. It's kind of amusing to think that when I initially shopped for subs I was looking at the $600 Hsu and a couple of other box subs and decided to go the kit route thinking that I was going to save money. If I add up all the material costs ($200 for the MDF, $150 for the veneer, $350 for the components, $100 or so from Parts Express, $40-50 for glue, varnish, assd hardware from the Home Depot), and add to that the ancillary expenses (like the $600 table saw and $100-200 of other hardware, router bits, circle jig, dado blade, other saw blades, etc.), my total expenditure comes out to about $1600. I think I actually still accomplished my goal of saving money, because the end result is on a par with a $2K - 3K sub. DS12-sealed DirectServo kit from Darren K. (Melbourne, Australia) Dear Brian, After sufficient break-in, I integrated the sub into my system using the ETF measurement software. With the sub placed between the speakers, the damping set to 'High' and extension filter set to '20Hz', the system measures within +/- 1.5db from below 20hz to above 200hz at my listening position. The sound is everything I'd hoped for with convincing weight, body, extension, dynamics and slam. These attributes, along with excellent articulation, provide a more toe-tapping presentation as the bass lines are more realistically weighted and detailed, not buried underneath. It's quite satisfying when you hear that some bass notes, previously thought to be a single note, are actually two notes or a series of shorter notes. Properly integrated, the sub never draws attention to itself. But when there is real bass in the material, the performance is far more convincing than it is without the sub. This includes drums, plucked and bowed bass, organ, piano etc etc. The presentation is more effortless, dynamic, realistic, and emotionally engaging. Properly built and integrated, this sub performs way beyond its price point. Many thanks Brian! ;-) DS12-vented Kit (from Patrick S. in N. California) After 5+ years of searching for the perfect balanced subwoofer for both music and Home Theater, I believe I’ve found it in the DirectServo Mini-Thunder. Over those 5 years I’ve owned and tested 15 different subwoofers, including the Hsu VTF-2, SVS PB12-ISD, Paradigm PW-2200, Earthquake MKIV-12, Velodyne Supercube II, and the ACI Force to name a few of the higher profile models.
First let me describe this little gem of a subwoofer. The MiniThunder cabinet is a Passive Radiator cabinet, designed by Acoustic Elegance L.L.C. (formerly Stryke Audio). The internal volume of the box is 2 cubic feet, the external dimensions are 17” x 17 “ x 17” with 3” legs. It has two 12” 670 gram PR’s that are side mounted opposite of each other, which tunes the enclosure to 20Hz. The Rythmik 12” DirectServo driver is down-firing and is powered by Rythmiks 350 watt DirectServo amp.
I was originally using a Stryke AV12 MKII 12” driver powered by a Rythmik Basic 350 watt amp. This setup worked very well for movies, however the bass was not as tight and defined as I would have liked for music. And as I’ve progressed in this hobby (and aged a little), music became my primary interest. My first thought was to install the Rythmik amp and Stryke driver in a sealed cabinet. So I contacted Brian Ding (owner of Rythmik Audio and maker of the amp), and asked if he could modify the 350 Basic amp by adding his custom Linkwitz transform add-on module to help equalize the AV12 MKII driver for a sealed box. He said he could, but with my main interest being music, he recommended I try the DirectServo amp/driver in the same MiniThunder cabinet. So after thinking it over I decided to give the DirectServo a shot.
For placement, I use a nearfield position directly behind my couch, 5” from the back wall, off center 1/3 of the way down that wall. This position is tricky to get the bass to blend with the mains (especially crossed over at 80Hz), which are 9.5 feet from the seated position, but really is my only option for placement. I optimized the phase and levels settings before testing. I set the Rythmik amps crossover to the max. setting, opting to use the 80Hz crossover in my 56TXi receiver. Considering placement and the frequency response of my speakers, this proved to be the best setting. The Rythmik amp also features a defeatable extension filter with separate frequency (14Hz, 20Hz, 28Hz) and damping control (Hi-0.6, Med-1.07, Low-1.33). For music listening tests, I had it set to 20Hz with the High damping setting. For Movies I kept it at 20Hz but lowered the damping to Low, which gives a 3 dB boost.
When I started my listening tests with music (of course), I had my parametric EQ bypassed (which I use to tame peaks two at 46Hz and 55Hz). I was very impressed with no EQ, but when the bass notes hit those freq. it still sounded a little “boomy”. So I set the EQ to take out those room peaks and got down to some serious listening. My first test is always with Fourplay’s “Chant” from the “Between the Sheets” CD. It has a powerful kick drum through most of the song. It is great testing overhang, for less articulate subs the drum note will continue "out" and sound blurred and muddy. With the DirectServo MiniThunder the kick drum kicked hard on que, but then stopped on a dime. Once more it blended perfectly with my mains, with absolutely no localization of the sub at all. Next up was the track "Django" from the "Ray Brown Monty Alexander Russell Malone" SACD. With none other than Ray Brown on bass. The DirectServo rendered the bass with such clarity and definition, it was so easy to just close my eyes and imagine Ray Brown right there in my listening room plucking those bass strings. There was definately no "one note bass" coming from this sub! Then I popped in Diana Kralls Love Scenes CD, which is loaded with some very rythmic bass on most of the tracks. Again, the DirectDervo had amazing rhythm and pace. Every pluck on the bass was tight and defined. I then put in the Eagles Hell Freezes over DTS concert DVD. Hotel California is one of my all time favorite songs and the bass drums in the opening minute are just outright powerful. The bass coming from the sub was deep and profound, but still blended perfectly with the rest of the soundtrack, never drawing undue attention to itself. In fact that is what impressed me most, no matter what kind of music I played, the DirectServo MiniThunder did what it was supposed to do, be a seamless extension of my mains in the lower frequencies (flat down to 17Hz). In all the subs I’ve ever owned, none could achieve this level of “musical definition”. However, though my main interest is music, I still need a sub that will transport me to those high impact action movies every once in awhile. I played around with some of my favorites, Air Force One, Lord of The Rings (especially that infamous ring drop), ID4 (opening scene is thunderous), and Armageddon, along with a few others. The DirectServo MiniThunder never bottomed out, showed no signs of stress, and literally shook my house (which is not easy to do with concrete floors)! The bass was never bloated or boomy, and you never knew it was there until it hit (and hit hard). I measured peak SPL's of 113 dB at 3 feet with a SPL meter. And that is louder than I would usually ever care to listen anyway.
To sum it up, this is the most accurate subwoofer I’ve ever owned and it’s got more than enough power to fill my 25 x 20 room. There are of course more powerful subs out there, but this one fits the bill for me and all things considered is relatively inexpensive. It took a lot of time and money to find the perfect sub for my listening tastes and needs, but this is it! Thank you Brian for a simply amazing Amp and driver. The combination of the DirectServo and MiniThunder cabinet is truly amazing. IMHO, it gives me the best of both worlds for music and movies! DS12-sealed Kit (from Bob Knox) Brian, you asked: Thanks for asking. I wanted to sort out the last serious problem with room acoustics before writing back. Combined with my new mains, listening to music with the Direct Servo 350 is a joy renewed. The sub went together great. I had a 16"X16"X18" cabinet ready with appropriate cut-outs when the kit arrived, and was able to finish assembly in under an hour. The 3/4" MDF box has double-thickness (1.5") front and back, and 1/2" MDF reinforcing panels attached inside the top, along the bottom corners, and bracing the middle 7" of the sides. (~ 1.64 cu. ft. internal.) I used a can of "Quiet Cote" to seal the inside. The resulting box was nicely non-resonant and weighed about 40 lbs. The outside was primed and painted (semi-gloss black) and then I covered the top, sides and bottom with pebble-surface black vinyl sheeting. Looks good, and is fairly inconspicuous with a dark gray carpet and black speaker grill cloth. Works as a low end table next to a chair we use occasionally. Might have been nice to have black-head wood screws included with the driver, since these aren't routinely available at home centers any more, but I made do with stainless screws and washers. They're behind the speaker grill anyway. The (smaller) screws supplied with the plate amp were a real help. I put ~1 lb of "Acousta-Stuf inside the box though I don't know what difference it made. Having the pre-made wiring harness to plug in the driver is a great idea, it made installation very easy. As expected, there's plenty of power for our smallish (13' by 15') room. I routed the reciever's subwoofer line out to the left channel line-level input on the DS350. Leaving the sub's volume control at ~1/3 has the receiver's Yamaha YPAO calculating only about a -1 db correction for the subwoofer. (Having the sub volume at ~1/2 results in a largish level correction at the receiver, so I opted for more line-in signal to the sub and less amplification there.) The sub blends well with my Axiom mains (M22ti) and center (VP150), and seems only slightly better with a 40 deg. phase adjustment than 0 deg. I have the right main sitting on the sub and the left main on a 16" tall, sand-filled stand I made to match the height of the sub (and the height of stands that Axiom recommends for this speaker model). Because my satellites (SL, SR, SB, and "presence L/R") are small Yamaha 2-way speakers, I opted to set the receiver's base crossover frequency at 90 hz. The cleanest blend came from setting *all* the speakers to "small" and setting "base out" to "subwoofer". The Axioms could go lower, but setting "base out" to "both" perhaps over emphasized 60-90 hz. If I could re-route the surround channel 90-120 hz signal to the mains, that'd be slightly better, but it's not noticeable on most material. Blending 2-channel music across the front 3 speakers (using Dolby PLIIx) got much better as I adjusted the crossover from 60 hz to 80 hz, and was about the same at 80, 90, or 100 hz. Going higher than 100 hz, I could hear the signal dropping away as the DS350 response rolled off. Less than 80 hz and the center channel didn't image as well in combination with the mains. 90 hz seemed like the overall best compromise. Eventually I plan to buy some better surround speakers that'll start to roll off closer to 80 or 90 hz. In the mean time, music sounds wonderful with the combination of the Axiom bookshelf/center plus the DS350 sub. My wife and I have been spending a lot more time in this room, listening to music. The setup works very well with movie sound-tracks as well. Our movie DVD's are newly engrossing. Also the other night we watched Lord of the Rings: Return of the King, on cable pay-per-view. Despite our Comcast converter putting out analog 2-channel "matrix surround" sound, the experience was very involving. Bass from the scene of Mt. Doom erupting had the house shaking. Music on the sound-track was exquisite. My wife is really looking forward to the sound during an annual 'video fest' she and a good friend have when the friend visits us August. The friend is a musician who plays the Viola da Gamba, and she may be able to offer a more professional assessment of the musical properties of the new set-up. The toughest part has been dealing with room gain and modes. I experimented with sub placement, using evaluation sweep tones on the Avia DVD. Things were closest to flat with a placement towards a corner and closer to the front wall than the side wall. I could minimize the peak at ~40 hz with careful placement, but not tame the 44 hz mode or solve other problems. I have home-made cylindrical (14" or 14.5" diam.) base traps in three corners. They do a nice job reducing long-reverb and really tightened up the mid-bass response when I added them. They don't do much for room modes at 38 hz and 44 hz. The 44 hz mode was the strongest, but other frequencies showed big (> +/- 10 db) variation moving a few feet around the listening zone. What I finally made (and installed this Saturday) was a polycylindrical diffuser 3' by 14', constructed with a couple of sheets of 1/8" tempered hardboard and a wooden frame. I had previously installed 4-5" thick by 15" wide fiberglas + burlap panels across the top corner of the back wall, hoping they would work as a bass trap. I assembled and painted the diffuser and added some fiberglas batting in the middle 6' or so to increase its sound absorption and broaden the range of bass absorption (nominally around 40 hz?). I then installed the resulting diffuser/absorber on the ceiling but with the back edge against the bottom of those corner panels (also spanning the corner). Our den has 3 faux beams ~6"x6" running lengthwise (15') along the 8' ceiling. Thus the diffuser is visually inobtrusive, between one beam and the back wall. The shape helps spread out mids and highs from the surround channels, while the structure absorbs errant deep bass. The results: the 44 hz front-wall-back-wall resonance was nicely tamed! I could then adjust the subwoofer's position to be 1/8 wavelength (45") from the right side wall to better tame the 38 hz side-to-side wall mode. Interestingly, not only did the booming response 37-44 hz damp down, and the drop outs around 50-55 hz come back up, but the sound near 30-35 hz got much better! The worst remaining feature is some significant point-to-point variation in the sound 60-65 hz. It's < +/- 10 db, and the other residual variations are smaller--as long as you don't stand right in a corner or against the back wall! Much of this was work to clean up sound I couldn't even hear with our previous gear. In retrospect, I probably should have made one of the corner bass traps 20" diameter, but this is an audiophile fine point. With the strongest modes damped down, now the subwoofer can really shine. Small room acoustics turn out to be rather tricky--something I didn't quite appreciate before. Having such a wonderful subwoofer, from your DS 350 kit, made it well worth the time and trouble to better understand what was wrong with our listening room and design appropriate solutions. Now after several months of gear shopping, research, measurement, design and DIY construction, I'm finally easing up on being such an instant 'audio geek' and taking time to enjoy the music! Best regards, DS12-sealed Kit (from Jim H. in VA) " Leaving the toggle as you set them, high damping, 14Hz, I set the crossover point as low as possible, with volume at mid point. The first recording was Thomas Murray playing the Woolsey Hall organ (E.M. Skinner) at Yale University. The 32' Sub-Bourdon in this CD is really felt, more than heard. My first reaction was WOW! The bottom end of the Klipsch LaScala's now went all the way down to 16Hz, and the room was moving! This is not your father's boom box! My wife came into the living room to tell me that the bedroom windows at the far end of the house were rattling, which is exactly what occurs then one is in a building with a real pipe organ and the 32' bottom CCCC of the pedal is played. Can you tell, I'm very happy with your system......" DS12-sealed Kit (from Mika V. in Finland) "I did compare the damping setting ..... I found out that the bass drum in Eagles/Hotel California/Hell Freezes Over is a nice test sound for comparing those. I compared it to my previous sub (Audio Pro Focus -made in Sweden) which is generally regarded as tight sounding. Focus was comparable to the 'mid' position. When in 'low' the sound is dull - bass is just a 'thump' without finer details in sound. It might be OK for movies tough and I know many prefer that kind of bass. In mid the tightness of the sound was at the same level. But in the 'high' position DirectServo was a clear winner. I can hear the details and the vibration of the bass drum in a way I have not heard before. The bass is tight, accurate and in control all the time. I've calibrated the levels with an SPL meter and even if the bass is tight it is still strong. Some subs might have the tight sound but the bass output is limited and the sub might not go so low (gives a fake feeling of tightness). With DirectServo this is not a problem. ...I'd like to thank you for the service and support I got from you. -- Regards, Mika V " Mika is also kind enough to send me some pics of this project, which I post here to share with everyone.
DS12-sealed Kit (from Eric O. in CA) "After a good bit of playing around, I have the sub pretty nicely sonically integrated with my mains. I found that going for the deepest bass extension really limited max SPL and that the 28Hz setting with high damping seems to work pretty well. The sub is articulate and nicely controlled over its entire range - no boomy or "loose" sounds eminate from it. I like the fact that I can now clearly hear the bass line on a jazz CD - or the lower pitches of the pipe organ."
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