Closing this loop in case someone in the future is interested in OB subs. I exchanged with several folks, some very knowledgeable in OB.
Danny Richie used sealed boxes in the back of the rooms at some audio shows to prevent large seat-to-seat variations for the audience. He doesn't use these himself. He recommends his OB, period. And if one wants to complement up to 30Hz with sealed he's good and in fact has recommended doing so in some cases. Danny does recommend 4 feet from the front wall, which is too much for my case (maybe I could get to 3 feet...)
I learned that when using OB subs it's very important to take your room dimensions into consideration, especially your front-to-back distance between walls (since dipoles radiate little to the side walls and ceiling/floor). To properly get to 20Hz you need that dimension to be 12 meters. My largest room dimension is 10 meters, close enough, but alas, my speakers are firing along the 5 meter axis (width) and for practical reasons I can't turn them around.
So I'll drop the idea of adding OB subs and add another couple sealed servo subs. And a MiniDSP 2x4 to apply multi-sub optimizer to allow delaying any of them as needed and other DSP for individual subs. Then the overall DSP will treat the DBA/MiniDSP as a "unit".
As to what drove Geddes to set up distributed bass arrays, I'll pass and let people do their reading. Geddes was proposing his approach well before 2014 and his papers and videos talk about minimizing seat-to-seat variations. Surely more subs provide more, pressurize the room more, etc, but that was his main driver. He also doesn't (or didn't at the time of the videos) believe time-alignment between subs and mains mattered, yet others do.
Toole gets into it too in several places. His chapter 13 in Sound Reproduction gets particularly into distributed bass arrays with time delays among subs for optimal results. This does require measurement equipment, a learning curve, and spending significant time to achieve the results. In my view Audio Kinesis are a great solution that simplifies the approach yet retains most gains for those who aren't interested in going that far in adjusting time and other variables. A great solution indeed!
Not interested in getting into a debate about this, though. There are plenty of materials online and Earl participates in some fora for those really interested. I realize there will be one/multiple replies to this, but really not interested to debate and won't engage.
Cheers and happy listening |
lewinskih01: "
@noble101 Indeed,Earl Geddes has said that subs has been enough for him, but 4 is better. It's important to note when Geddes talks about "better" bass he's referring to seat-to-seat variations across the room. So bass is more Even across the room. He isn't talking taut, 3D-like, fast or other descriptors often used for "good" bass."
Hello lewinskih01, I'm not certain you're claim about Geddes's meaning, when he talks about "better" bass, is correct. Yes, one of the main benefits of his 4-sub distributed bass array (DBA) concept is very even bass distribution performance throughout the entire room with very little seat-to-seat variations across the room. But another main benefit of his 4-sub DBA concept is that this very evenly distributed bass performance is also consistently perceived as very high quality bass as described by the familiar good bass audio adjectives such as taut, fast, smooth and detailed. Duke LeJeune, the owner of Audio Kinesis, is still a friend and was an associate of Earl Geddes, circa 2014-15, when he told Duke about the benefits of utilizing the 4-sub Distributed Bass Array(DBA) concept he invented/discovered and gave Duke permission to use the concept as he wished and without charge. Subsequently and fairly quickly, Duke introduced the AK Swarm 4-sub DBA that was reviewed very positively in 2015 by the Absolute Sound magazine. Here's a link to that review: https://www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system This is just a sample from this review praising the high quality of the Swarm's 4-sub DBA system's bass performance: "
Now any addition of full-range bass gives some of this effect. But the Swarm gives more of it. Not more bass than other subs—lots of them can be turned up to give plenty. Rather, there is better bass with less signature from the listening room." My main point is that both of these main benefits of the 4-sub DBA concept, evenly distributed bass and high quality bass, are not subtle qualities at all. These are both very obvious qualities that were easily perceived by both the Absolute Sound reviewer and myself as a user. I seriously doubt that either Earl Geddess, as the concept's inventor/discoverer as part of his PHD thesis, or Duke LeJeune, as the concept's adopter/manufacturer, are unaware of these two main benefits nor hesitant to refer to both of these as qualifying as "better" bass qualities when discussing the concept. After utilizing the AK Debra 4-sub DBA system for the past decade and counting, I can also state with certainty that bass power, impact and dynamics are also other main characteristics of this concept. fwiw, Tim |
A coupla decades back Gradient made dedicated OB subs for both the QUAD ESL (aka "57") and the 63. They did that for a reason: QUAD owners had long been searching for a sub that would "mate with" their dipole ESL’s, to no avail. Non-dipole subs simply do not "mate with" dipole loudspeakers. Why? That information is readily accessible in the literature, including in the writing of Siegfried Linkwitz. I won’t repeat it here; those with the requisite intellectual curiosity will find it on their own. Beside, I have previously done so, and that info has been ignored for reasons at which I can only guess.
The statement "the mate with thing is a non-issue" simply reveals the ignorance (the term used in a non-pejorative spirit) of the person who uttered it in regard to the very real technical problems encountered when attempting to mate a dipole loudspeaker with a non-dipole subwoofer. It is HE who should be ignored. ;-)
The OB/Dipole Sub currently available from the collaborative team of Rythmik’s Brian Ding and GR Research’s Danny Richie is a FAR better product than that of Gradient. Again, the reason that is so may also be learned with very little effort. I’ll give you a hint: The Rythmik Audio/GR Research OB/Dipole Sub is the only sub of it’s kind in the entire history of hi-fi music reproduction, an OB/Dipole sub incorporating servo-feedback woofers. Now THERE’S a mating!
The OB Sub is the first and only sub using dynamic woofers I have found which rivals the bass panels of the Magneplanar Tympani T-IV’a (which I also own) in bass quality. It was those panels Harry Pearson mated with the m/t panel of the Infinity IRS to create his "super" speaker. The IRS includes massive woofer enclosures containing multiple servo-feedback dynamic woofers, yet Harry preferred the bass panels of the Tympani T-IV. I formerly owned the mini-IRS---the RS-1b, which also includes separate enclosures with s-f woofers. The OB/Dipole Sub easily bests the RS-1b woofers. |
I listen nearfield with a Rythmik FM8. It's on the left side and sounds like it's on the left side. I need another to iron out that problem. Otherwise it's very natural sounding. |
@noble101
Indeed,Earl Geddes has said that subs has been enough for him, but 4 is better. It's important to note when Geddes talks about "better" bass he's referring to seat-to-seat variations across the room. So bass is more Eben across the room. He isn't talking taut, 3D-like, fast or other descriptors often used for "good" bass.
@iananderson
I know of a guy using Quad 63 and 3 Gradient subs who is looking into GR Research OB subs with great interest. I have not heard his setup, but FWIW he's a professional bass musician at Lyon's opera...his understanding of how natural bass sounds is surely better than mine!!! |
Hello kenrus,
scm also offered very good advice, in my opinion for 2 reasons:
1. I believe the Hsu ULS-15 MKII is also a very good sub that may even outperform the SVS SB-1000-Pro but it's $800 plus $90 shipping and handling, which totals almost $900. It's also larger, due to its 15" woofer, at about a 1.5 foot cube. Head to head it likely outperforms the SVS but I believe a pair of the SVS subs will significantly outperform a single Hsu sub in your room and only cost a touch over $50 more, due to the free SVS shipping.
2. Scm mentions the idea of using 3 total subs in his room and I think this may have a good chance of working well in your room, too. In effect, you already have a sub module attached to the bottom of each of your ML main speakers. Even though these sub modules aren't currently positioned in your room, and in relation to your listening position, for optimum bass performance since they're probably currently positioned for optimum mid/treble and imaging performance at your LP, one additional and optimally positioned sub in your room could, theoretically, significantly deepen the perceived bass in your room. I'm thinking a single, slightly larger sub with a larger woofer (15" or more like a Hsu ULS-15 MKII or another, larger, sealed or ported SVS sub that has deep bass extension down to 20 Hz or lower) may work very well if it's optimally positioned and configured. This should be considered an alternative option to the pair of sub option I discussed previously.
This works because, even though only 1 of your 3 subs would be pumping out bass below 24 Hz and down to 20 Hz or lower, you would perceive all of the bass in the room as extending down to the deepest sub's capacity. This is explained in the field of psycho-acoustics if you care to google it and learn more about this subject and phenomenon.
As others have mentioned on this thread, Dr. Earl Geddes, the original inventor of the 4-sub distributed bass array(DBA) concept, claims that 3 subs can sometimes perform as well as 4 subs in a room.
Buying from SVS, or another company that offers free in-home trial periods and returns, has the added benefit of allowing you to try out either or both options without taking any financial risk.
Tim
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I'm using five subs- 2 sealed, 2 ported, one isobaric. They work equally well with Talon Khorus and Tekton Moab. I cannot even begin to tell you what a non-issue this "mate with" thing is.
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I’ve been aware of the great benefits of the DBA swarm through many post here on the ‘Gon. Technically GR’s OB servo design make a ton of sense to mate up to my Quad 63 USA monitors.
has anyone seen a post of a design that specifically mates with that speaker? Should I OB everything? Or would I be better to mix OB in the front, and ported / sealed in the sides or back? |
You guys have been amazing with your ideas and advice. Thank you!
I’ve been laid low because of medical problems. Once things improve (soon) I certainly have a lot to consider!
Thank you, again! |
I use two HSU ULS-15 MkII subs in addition to a Revel Ultima Sub 15 all are sealed.
The ULS15 is the only sealed sub that HSU sells and is very nice for the money.
We`re in the process of setting up two brand new SVS SB1000 Pro`s that are being used along with a sealed down firing DIY Rythmik sub that has the GR 12" driver in it for my daughter and her husband in a nicely done basement stereo room.
Plenty of power and the phone app is really nice to have ! Just sit in the listening spot and dial it all in...pretty cool |
Hello kenrus, I think mike_in_nc gave you very good advice: the key is good integration with your main speakers, a pair of subs will perform much better than a single sub (smoother, faster bass, easier to integrate and provide better bass dynamics) and it's best to buy subs that offer a free in-home trial period and full refunds if you're not satisfied. I agree with this completely. I also agree with mattchristian that a pair of the SVS SB-1000 sealed subs are a very good choice. You'd need to buy a pair of these subs used, however, since SVS recently discontinued this model. I don't know your budget and goals, but if you're looking for the best bargain, I think a used pair of the older SB-1000 subs in good condition would be your best option. If you prefer to buy new with a 5 yr warranty, I'd suggest checking out a pair of the SVS SB-1000 Pro subs for $499/each, or a $50 discount if you buy 2, at $950/pair. These are a newer refreshed and updated version of the discontinued SB-1000 model at the same price. These are also very compact (roughly a 13" cube), have a 12" woofer and have a rated bass extension down to the audible limit of 20 Hz. They offer free shipping, a free 45 day in-home trial period and a full refund if you're not completely satisfied. If your budget is a bit higher and your goal is state of the art bass performance that will make your room seem larger, I'd suggest you consider the Audio Kinesis Swarm or Debra 4-sub distributed bass array (DBA) system for about $3,000: https://www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system Just a few useful things for sub installation and setup I've learned through research and experience over the years: Two subs will perform and sound about twice as good as a single sub and four subs will perform and sound about twice as good as two subs in virtually any room. Humans are unable to localize (discern exactly where a sound is coming from) with bass sounds at frequencies below about 80 Hz and are progressively better at localizing sounds as their frequencies rise above about 80 Hz. It's very important that each sub is positioned optimally in the room, and in relation to the designated listening position, for best performance. I suggest you google and use the "sub crawl" method for easiest and optimal positioning. Once the subs are optimally positioned in the room, the Volume, Crossover Frequency and Phase controls need to be optimally set on each of the SVS subs or once for all 4 subs, on the supplied amp/control unit, for the Audio Kinesis DBA system. Best wishes, Tim |
@lewinskih01;By jove, I think you have it! 18" woofers have gained favour amongst OB enthusiasts because of their higher max-SPL characteristics in comparison to smaller woofers (and 15" for the same reason). Open baffle woofer design results in lower output relative to sealed and ported---using the same basic woofer (the woofer in the OB Sub is the same as that used in the F12, only electrically optimized for OB usage.), a characteristic cited against them by opponents of OB subs.
That criticism is justified and fair, but there is a solution, one employed by both Rythmik’s Brian Ding in the OB/Dipole Sub, and by Siegfried Linkwitz in his excellent OB/dipole loudspeakers: a dipole cancellation compensation circuit, which provides electronic boosting of the signal sent the woofer(s) at 6dB/octave below 100Hz. Problem solved! Or at least mitigated: even with that circuit, an OB does not produce as much output as a sealed or ported, fed the same amount of amplifier power. You can’t have it all! To get a slight increase in SPL, the 3-woofer OB Sub is offered. And one can of course stack multiple OB subs, using a separate plate amp for each OB Sub H-frame and it’s woofers.
Speaking of subs with 18" woofers: did you notice Rythmik now offers 18" sealed and ported models? Wow! The 15" models already produce a lot of max SPL, I can’t imagine the 18". And with servo-feedback!
Does your friend with the F8’s realize he owns collector items? Brian Ding discontinued the model (and no longer has the 8" woofer manufactured for him), which was popular for mid-bass use. A lot of audiophiles think smaller woofer = "faster" bass, but Ding insists his 12", 15", and 18" woofers are just as fast as the 8". What makes a sub sound "fast" is how quickly the driver stops and returns to "rest" after the signal stops; the Rythmik servo-feedback design provides stop-on-a-dime woofer control and sound quality.
As for OB sub-to-sidewall distance: Rejoice! Due to dipole cancellation on either side of the OB Sub frame (inherent in open baffle design, as described and explained in my earlier post), you may place the OB Sub right against the wall if you wish. Or lay it on the floor---there is no output on either side of the OB frame! As long as the sub fires down the length of the room, you’re good.
As for OB Sub to front wall (behind the Sub, not the listening position) distance: as with all dipoles, a minimum of 3’ is required, more encouraged. Of course, you may try different distances to optimize direct-to-reflected phase correlation and loudspeaker/sub blending, but the continuously-variable phase control (0-180 degrees phase rotation, creating 0-to-16ms delay) makes that unnecessary. But remember: a phase control can only delay the signal, not send it back in time. ;-) |
You really need several subs in any system no matter what the room size. It is just a matter of which sub you decide on getting. I have a lot of experience with many different subs in my listening area which is a very complex room to fill properly. The area is not your more common rectangular room with a flat ceiling; I have around 14K cubic feet of space with an 18 foot vaulted ceiling in the main section with overhead balconies, stairs and a cantilevered overhead room in the rear section adjacent to the main entrance which open. There is a lot of glass on the eastern wall, mostly stone on the western wall with natural wood on both the north and south wall areas where the stairs are located going up to the cantilevered balconies and room.
After several years of testing multiple combinations of speakers and subs, I have this place really dialed in to the point it sounds like a concert hall. I have about 7000 watts of power between my two mono block main amps and the various other subs strategically placed for wall location and spacing/phasing. My brother who is a professional video producer and audio engineer said the system sounds the closest to anything he has ever heard to a real live concert (he has worked with a number of major national rock bands). The key to this system is twofold: great subs and great placement of the speakers with proper phasing. Of course the main speakers are the most important part too.
After extensive testing and trials, I settled in on a pair of Bryston Model T main speakers which have triple 8 inch woofers, dual 5.25 inch mids, and dual titanium tweeters and they are set up with the fully active input system, but I am not running the fully active electronics, instead I am using the super heavy duty passive PX-1 massive external crossovers and each speaker gets 2300 watts from a mono block amp.
For subs, I have used a number of products (several of which have been spoken of in this thread) and I'd skip over all of them as I have found the Axiom Audio subs to be the best of the lot by a long margin. First of all, they have the best drivers which are indestructible and their power supplies are all massive linear supplies with monster toroid wound transformers. They do not use switching power supplies as every other sub I tried uses. The dynamic head room is hands down way out over the others which makes for the cleanest, pure tight bass I have experienced. These subs are what makes low end musical! Every other sub I tested sounds like bottom of the lake muddy low visibility. If you do not want to "hear" your low end, that is know where your subs are in the room, but wish to have just balanced, clear, full range music, you owe it to yourself to try these subs out.
My most beautiful sub by far of the lot is my Bryston Model T sub with its triple 8 inch drivers and an 800 watt linear amp. This thing just sings with beautiful low mid range bass, it is built by Axiom Audio (Axiom and Bryston are the same company). It has a gorgeous black ash real wood cabinet with incredible internal bracing, there are no resonances at all.... it was not inexpensive though, $5600 and unfortunately they no longer make this sub.
For you particular room, I'd look at the Axiom EP500 which is a fabulous 12 inch single driver sub and a 500 watt linear power supply (do not be misled by power ratings on subs as most rate their power with a switching supply which lacks the clean dynamic power you will be getting with low end music and a linear supply with a ton of capacitors and it will do a far nicer job). I have one in the room and I just love it! I also have the EP800 with dual 12 inch drivers. All of the subs have the same amp design, just with slightly different power output based on the sub, but the exact same full range phasing controls which are a must for setting up and balancing the sound based on the room and speaker placement.
My advice due to extensive experimentation in a difficult area to properly fill with balanced sound is to go look over the subs offered by Axiom as this is their direct to consumer side vs. sold through full service dealers which is Bryston. The Bryston speakers are the flagship items and will cost you twice as much (and the build quality reflects it), but the Axiom is priced very well for anyone looking to keep things within the reality zone and its also very top notch build quality. Its all built in Canada, no made in China stuff here!
That is my 5 cents worth :) |
@bdp24
Thanks again. You are right I was misunderstanding what the models implied. I totally get the F12 since mine are F12-like in heavy DIY sealed boxes. I thought the F12G were paper cone and open baffle (like Danny's designs), but I see on Rythmik's site they are sealed. So let me rephrase and provide perspective for what I was saying:
I though he ran F12 up to 40Hz, xo to OB subs (his Kit 4 or 5) from 40 to say 180Hz, and then xo to another driver. I guess my thinking was biased by the way I set up my system. And I know another user who runs multichannel stereo and used F12s (to 50Hz) in such a fashion with F8s above (frequency-wise) to 175Hz and JBL M2 above, so I though Danny was doing this but on OBs.
I totally understand why he does it the way you describe it too: below 40Hz he gets 4 sources playing (F12s and OBs) so a DBA. Worth noting Earl Geddes argues for 3 or 4 subs and says the 3rd and 4th subs don't need to be as powerful, which in Danny's case would be the OBs below 40Hz. Then Danny gets OB bass with servos from 40Hz to whatever he xo, and let a regular driver take it from there. Makes a lot of sense and would demand a redesign of my system because those F12Gs would replace my dipole 18" but would not reach as high and the smaller surface (2x12" vs 1x18") I guess would be perceivable. In my prior iteration I had 2x10" in the midbass and the move to 1x18" was a significant step up in impact of bass while also having dipole texture (of course an 18" in a box would have more impact than it in dipole). Maybe I need the 3x12" GR Research :-)
Good food for thought!
BTW: do you place your OB subs close to the side walls? In my case I would need to, maybe 4 or 8" from the side walls in the front corners, 2 or 3 feet away from front wall...not ideal distance to front wall, but space constraints. I wonder if being close to the side walls would further detract from them. |
Perhaps a bit messier than integrated, I run two Scaena 18" subs with a pair of Crown 1502 amps and an old Maxdrive 3.4 pc. As was noted eariler, it is the DSP that is the magic sauce though.
My listening room is fairly large (17X32) and they fill the low end perfectly.
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@lewinskih01: Your question has me confused. After stating "So he's using F12's up to 40Hz", you then ask "Do you happen to know how high he crosses over to the F12G's?" Aren't those the same? Or am I not seeing what you're asking?
You're not differentiating between F12 and F12G, are you? The "G" designation is used in reference to GR Research, the only difference between the two models being the use of a paper cone woofer in the F12G, an aluminum in the F12. Danny prefers paper cone woofers, Rythmik's Brian Ding metal.
Danny uses the OB sub from whatever frequency is required by the loudspeaker it is used with (up to 300Hz), down to as low as it will play, which is into the teens (below 20Hz). In other words, with a low-pass filter on the sub but no high pass. When he adds a pair of F12's, he still uses the OB sub full range, without rolling off the bottom end to "make room" for the F12's.
Le me reiterate that the 40Hz figure I mentioned is the frequency I believe Danny uses the F12 up to when coupled with the OB. I may be mistaken, it could be somewhat higher, though certainly not above 80Hz. |
+1 to @audiorusty on comments about JL Audio "e" series (I have an e110--superb sub for limited space) and separate crossover.
My previous sub, though wonderful sounding (SVS SB-1000) has a rather non-transparent, poor-sounding low-pass output crossover. Instead I got a very good quality Marchand electronic crossover and no longer relied on the sub's crossover. Big improvement, plus the fact is relatively few subs even have a low pass output (RCA pair), much less a good sounding one.
As it happens, my e110 is one such sub. But I found it more convenient to continue using the external crossover than the JLA's crossover output, due to a pesky ground loop.
If you don't happen to have an integrated or receiver w/quality filtered outputs for sub + mains, an external crossover is the way to go. |
Has anyone tried the Thor's Hammer? |
@oldhvymec
Not familiar with what VMPSs bass is. I believe you are also into DIY OB speakers. I'm also running an active system, so no passive xo parts between amp and corresponding driver. I couldn't be happier. Currently a 4-way active stereo system...although I smell bdp24 comments might be leading me to a 5-way ;-) |
@bdp24
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.
This is great to know! So he's using F12s up to 40Hz. Do you happen to know how high he crosses over the F12Gs?I guess I have some chewing to do: I run F12s to 65Hz and from there unbaffled dipole 18", so kind of similar to Danny, but he has servo dipoles above the F12s. |
Two Rel T5i's, a Rel T7x and a SVS SB2000. Fixed 90% of my low frequency issues. |
I agree about looking at REL. They are the first subs that integrate with my Maggie 3.7s. Very fast and great quality. |
The new x series from REL are incredible. Check out my T/7x review on their website www.rel.net |
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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. |
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...
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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. |
Depends what your budget is suggest
Looking at Velodyne's new Deep Blue 15"
Or if budget allows DD15+ |
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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. |
@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. |
@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. |
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¢ |
My main listening room is 13’x9’. I run three HSU subs. To my ears,they work very well. |
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. |
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. |
@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 :-)
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@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! |
@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.
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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. |
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. |
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! |
@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...
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Hsu Research, 18” Velodyne, or the “El Pipo” DIY sub ( this would be my choice”. |
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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. |
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`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’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. |
