Planar Speaker Asylum

Welcome! Need support, you got it. Or share you ideas and experiences.

Planar Speaker Asylum

One great sub, or 2 good ones?

24.7.103.234

One of the last things I am buying gearwise is the subwoofer.

Is it better to get 2 or one great one. Lets say I have 2k to spend. Would I be better off with something like the Velodyne DD-10 or maybe 2 of the minivees or optimum 8s?

And do you have any recs for SMALL subs that will blend well with maggie?

Follow Ups:

Follow up question - Dawnrazor 15:56:23 10/22/09 (13)
Ok thanks for all that responded, but only one poster really read what I wrote and I didnt spell it out that good. Sorry.

Lets start over. I have to have a small sub with a 13x16in footprint at the max. So 15 inch subs and 4 subs around the room arent going to fly in this case....the wife has reclaimed her living room and the sofabed couch I sleep on due to my snoring (not because I am a bad husband :)) needs to join the audio room. That leaves little space.

So I need SMALL subs that fit in the 13x16 in space so the closet door will still open. Given this the sub will be on the back wall by the bed and about 21" away from the sidewall.

Will this be an OK place for the new subs? The room mode page I was directed to shows some issues in the 160 and 140hz regions. Will having the driver 16" into the room and 26" (21"+5" if I get a 10 Inch sub) from the sidewall be a bad position?

Another option puts the driver the same 26" from the sidewall but 23" OFF THE FLOOR. Which would be best?

What subs would you recommend given the size requirements?

About Rel. I understand the post not to buy the velodyne. But as much as i like Rels sound and their high level hookup instructions I can't get past the long wire I would need to connect my amps to the sub. How can you get the correct timing they talk about when the sub amp gets the signal 34ft later?

Finally, Dr. K's post made sense about the dsp correction. With a limited space for placement wouldnt that be a big benefit over subs that dont have that option?

Thanks!!
- RE: Follow up question - emsquare 17:56:23 10/23/09 (0)
  Take it for what it is worth... On a recent outing to a local dealer, I remember a noteworthy comment that is a hear-say kind of thing. The owner had not long back had met with Mr. Thiel being a dealer of his speakers. Of course they talked about whatever it is that manufacturers talk about with dealers but the Thiel subs were discussed. Even though he was pleased with his sub-woofer designs he felt that the cutting edge product was REL. Saying that one of his prime goals was to better REL's speakers.
  Now I have not listened to any of REL's sub-woofers and just can't say anything about their quality. But when Jim Thiel made a statement like that I tend to think that it would be a worthy consideration. I mean seriously, how many speaker designers can one name?
  Again this is all FWIIW.
  
  In search of musical bliss...
  
  Edits: 10/23/09
- RE: Follow up question - leon 14:53:10 10/23/09 (0)
  HSU VTF 1
  
  Small, will fit in your space and easily work into a 1500 cubic foot space.
  
  Inexpensive, too! Budget permitting, a pair would be killer and not overdone.
- long cables and acoustic timing - wazoo 16:14:33 10/22/09 (10)
  There's a huge difference between the speed of light and the speed of sound. Electricity essentially travels at the speed of light, so a few (or even 30) extra feet isn't going to monkey with timing in any significant way (in other words, that just isn't a problem). When you went with a capless XO, did you worry about the treble-mid/bass timing difference that would result from the signal that had to pass through that long stretch of copper (the inductor)?
  
  "Jazz is not dead - it just smells funny" FZ
  - What about the main question? nt - Dawnrazor 10:11:33 10/23/09 (1)
    d
    - I don’t think I’m qualified - wazoo 07:06:37 10/24/09 (0)
      If my choice is between a single or a pair of subs (all else being equal), then I think the answer is simple – two. Two grand should buy a pair of really good subs – my little RELs were just over that for the pair (not sure what the price structure is for the current line). As far as which subs are your best bet – I have no idea. The 10” RELs produce adequate bass for my tastes, though they aren’t floor shakers like the 15” Klipsch I used for HT.
      
      Like you, I have my own bedroom because of my snoring (a condition I inherited from my mother who has been diagnosed with sleep apnea – went to a center for observation) - nice to know that I'm not alone in this regard. Fortunately, the MMGs still have their place in the living room. I have my AR91s and the Stax earspeakers (each driven by its own Parasound amp - older and not as nice as yours, but I think both are fantastic, so I hereby give the raspberry to you know who) in my bedroom – work very well in the relatively small space.
      
      I’ve never met a sofa bed that I could stand for more than a night or two (or even that long). I hope yours is far superior to any of those on which I’ve tossed and turned. Before my son moved out, I spent about a year sleeping on an air mattress in the living room. A few of them (they didn’t last for more than a few months of nightly use) were very comfortable. Using something like that instead of the sleeper sofa (you were talking about one of those fold out things, right?) might open up more possibilities for locating the subs. I must say, however, that it’s very nice to be sleeping on an actual bed again – bought one of those Tempurpedic mattresses and they are awesome .
      
      Honestly, I’m not qualified to be giving advice about locating your subs – or to judge whether or not they will work well in the location you have available. Remember, I just stuck mine under my MMGs, but my MMGs are pointing (more or less) at me. Maybe I should give the sideways setup another go – this time with my CrowleyPans.
      
      "Jazz is not dead - it just smells funny" FZ
  - RE: long cables and acoustic timing - Dawnrazor 16:31:09 10/22/09 (7)
    Hey Waz,
    
    Yeah I know all that. SOme smarty pants will come out with some math to show it doesn't make a difference. But I am skeptical. hey, its my nature. The Mags are closer than the subs and they get the signal before the subs so how their sounds can arrive at the same time is a mystery to me. Now if you are saying that I cant hear the difference then that is one thing I suppose.
    
    I could make some Crowley pans and put the subs there I suppose and that would be right by my amp. But I am not sure that is the best place for some subs.
    
    YOur point is taken about the capless crossover. I am an idiot with crossovers I think but in that application, do the highs really move through the inductor?
    - well, no - wazoo 16:53:04 10/22/09 (6)
      I was just being a smartass, and wasn't really thinking about the design of that XO - the coil is acting as a shunt, eh? In a standard parallel XO, however, there certainly is a signal passing through a rather long coil of copper (which is what I started to type, then thought about what you had tried). Now I'm confused though - you're a skeptic (I thought I was the skeptical nutcase here)? The point I was trying to make is that the differences in length in your situation would result in a timing shift measured in nanoseconds - well below the threshold of audibility.
      
      "Jazz is not dead - it just smells funny" FZ
      - RE: well, no - Dawnrazor 16:59:10 10/22/09 (5)
        
        In Reply to: RE: well, no posted by wazoo on October 22, 2009 at 16:53:04
        
        Well I thought in the ASYLUM there would be room for at least 2 skeptical nutcases...
        
        Probably why i like you so much.
        
        Yeah, you are probably right I am going a bit overboard.
        
        On those rels, can you shorten the cable?
        
        skeptic (to be an official member of the club) - wazoo 04:50:58 10/23/09 (0)
        
        In Reply to: RE: well, no posted by Dawnrazor on October 22, 2009 at 16:59:10
        
        I think any proper skeptic should have Michael Shermer's 'Why People Believe Weird Things' in his book collection. Of course, a couple of older books also belong - Thomas Paine's 'The Age of Reason' (1794, 1796) and Charles Mackay's 'Extraordinary Popular Delusions and the Madness of Crowds' (1841). Carl Sagan's last book 'The Demon Haunted World' ought to be in there too. Crap, here I go again. I was going to mention one book as a requirement and then I just got carried away with the idea - sorry. Oh well, all of those and more are very good books on how rational thought gets derailed. (Did I mention Michael Zimmerman's 'Science, Non Science and Nonsense'? How about... (Even one of Bill Gates' former cohorts, Richard Brodie wrote a great little book on the spread of memes, 'Virus of the Mind'))
        
        "Jazz is not dead - it just smells funny" FZ
        
        shorten what cable? - wazoo 17:23:28 10/22/09 (3)
        
        In Reply to: RE: well, no posted by Dawnrazor on October 22, 2009 at 16:59:10
        
        Did my RELs come with cables? I guess they did, but I'm not using them. I made my own. Wait a tic - yep, I have some wires that look suspicious in the closet. Sure, you can cut them down to whatever length you need. One end is terminated with the Neutrik connector, but the other end is just three wire ends.
        
        "Jazz is not dead - it just smells funny" FZ
        
        RE: shorten what cable? - Dawnrazor 20:06:03 10/22/09 (2)
        
        In Reply to: RE: shorten what cable? posted by wazoo on October 22, 2009 at 17:23:28
        
        Ok,
        
        That helps. I still dont know how to hook it up. The manual talked about differential amps and I think I have one but dont know.
        
        I suppose I can figure that one out though.
        
        ;- ) lotsa ways - wazoo 20:48:53 10/22/09 (1)
        
        In Reply to: RE: shorten what cable? posted by Dawnrazor on October 22, 2009 at 20:06:03
        
        I recently changed to the second pair of RCA outs on my preamp, then added a dbx120 I picked up for $50 off eBay (has a problem with the main outputs (pop goes the capacitor), but I'm only using the sub outs - so, no problem (these frequencies really aren't going to be negatively impacted (audibly) by a little tweaking). Actually, it's a nice solution - allows me to correct for shortcomings in many mixes (some material doesn't need any help, so I just dial it out of the sonic landscape).
        
        I've pretty much decided that this is how I want to keep my subs connected, but I still want to do something about the MMG XO (will stay in the line level realm henceforth) - want to rolloff the bass above the resonance peak (would like to have the -3dB point around 60Hz). I also want to spread the XO region a bit - not as much as 2nd gen stock.
        
        I formerly had each sub connected to each channel of my amp - the two signal wires for each sub connected to the positive of its respective channel (in parallel with each MMG) and the common wire to the negative. It worked great that way, but the added enhancement (judiciously applied) makes my current setup far superior.
        
        Before the purists sharpen their claws and tear into me good over using such a device (of artificiality), I should remind them about what may well have existed in real life but only made it into the recording as harmonics. This thing just recreates the lost fundamentals - yes, I know it can be abused, but so can many other things. I'll tell you this: It makes many recordings of '70s progressive music sound far better (only way I can listen to Yes). It's one thing to turn a sub's gain up; it's quite another to feed it a fundamental an octave down (from what would normally be fed).
        
        "Jazz is not dead - it just smells funny" FZ
        
        RE: I do the same. - Travis 06:40:19 10/23/09 (0)
        
        In Reply to: RE: ;- ) lotsa ways posted by wazoo on October 22, 2009 at 20:48:53
        
        My 70s jazz fusion ceedees and elpees benefit from that extra low bass.
        
        "If people don't want to come, nothing will stop them" - Sol Hurok
Four - Peter Gunn 07:28:05 10/22/09 (4)
I didn't have the swarm yet when you visited me, but I can't recommend it enough. It's magical. It also isn't just "for bass" because what it does creeps well into the lower midband reinforcing artifacts there which results in a more fuller presentation across he board.

You can buy a set and still pocket $500 or so. IMHO it is the best sub system one can own with maggies, and the fact that it was specifically designed with planars in mind doesn't hurt either.

The only caveat to owning them is the space they take up. (however they can be positioned almost anwhere) So if that is a non issue, this is what you want.

It's all about the music...
- RE: Four - Avocat 08:35:01 10/23/09 (1)
  Could someone please explain what a "swarm" is? Is this like four or more subs? Eight or more? If it's the make, I've never heard of it.
  
  Jim
  - RE: Four - Bibo01 08:55:44 10/23/09 (0)
    http://www.audiokinesis.com/product/content_akplanetarium.htm
    http://www.audioasylum.com/reviews/Speakers/Audiokinesis/The-Swarm/speakers/247336.html
    http://www.audiocircle.com/index.php?topic=60103.0
    
    Edits: 10/23/09
- indeed - wazoo 16:17:13 10/22/09 (0)
  To a great extent, the more the better (at eliminating the impact of room modes). Two is better than one, and four (distributed) is better than two!
  
  "Jazz is not dead - it just smells funny" FZ
  
  Edits: 10/22/09
- RE: Agree - Travis 15:54:23 10/22/09 (0)
  Hadn't thought too hard about the "lower midband reinforcing artifacts" but I think you are right.
  
  I use them with a hybrid stat to good effect.
  
  "If people don't want to come, nothing will stop them" - Sol Hurok
Regarding the MMG's bottom end.... - kootenay 22:13:34 10/21/09 (0)
It's best to use two subs.

If a thing's worth doing, it's worth doing well
(Proverb)
RE: One great sub, or 2 good ones? - emsquare 14:54:53 10/21/09 (9)
Offering an opinion...

Stereo subs are preferable. Mono summing subs can do a nice job. But when it comes down to it, they are compromise and not an equivalent to stereo drivers. I do not believe there is any such thing as a fast sub. Just deficient subs. And for the best results they should be incorporated as the new low end in the speaker system. For MMG's, you will be converting a two way into a three way speaker and it is best to place them that way. Corner loading may give you better efficiency but not a better blend. My tendency is to view speakers as a transducer. To unify a transducer it just makes sense to physically place them that way. I recognize that there are alternatives but this is all just an opinion.

In search of musical bliss...
- hmmm, that sounds familiar - wazoo 04:04:23 10/22/09 (8)
  The problem was that I didn't have room to place them on the floor next to my MMGs (I actually do have the space now, but that's another story - reduced equipment, then abandoned HT), so I went vertical.
  
  The enclosure above the sub formerly contained a crossover, but I've moved that upstream. It's not a 3-way implementation yet, but that's the plan.
  
  "Jazz is not dead - it just smells funny" FZ
  
  Edits: 10/22/09
  - Cabinet Isolation - Showme 08:53:27 10/22/09 (5)
    If you don't mind me asking, what material do you use between the sub and the cabinet?
    
    Ray
    - RE: Cabinet Isolation - Rod H. 11:17:15 10/22/09 (4)
      IIRC, Waz uses air!
      - RE: Cabinet Isolation - Showme 13:27:43 10/22/09 (3)
        
        In Reply to: RE: Cabinet Isolation posted by Rod H. on October 22, 2009 at 11:17:15
        
        The picture didn't look like air?
        
        Ray
        
        okay, I can chime in now - wazoo 16:04:20 10/22/09 (0)
        
        In Reply to: RE: Cabinet Isolation posted by Showme on October 22, 2009 at 13:27:43
        
        Rod is right - the main isolation method is space, but I figured I'd apply some acoustic damping material (from Parts Express) for good measure. I really don't know if it makes a difference, but there was space for it and it didn't cost much.
        
        Necessity was the mother of invention - I wanted to pair a sub with each MMG and didn't have the floor space. I think this works very well, but I wouldn't claim that it's the best way to accomplish the pairing (unless one has a similar shortage of floor space).
        
        "Jazz is not dead - it just smells funny" FZ
        
        Sorry...:-) - Rod H. 15:29:08 10/22/09 (1)
        
        In Reply to: RE: Cabinet Isolation posted by Showme on October 22, 2009 at 13:27:43
        
        Didn't mean to be a smart alec. I thought Waz would chime in. The subs are separate, and there's a space between the enclosures and the bases for the Maggies, with no contact between from what I remember him saying previously. Any vibrations would have to travel to the floor, then back up the Maggie bases. That's why I said "air", because of the air space.
        There's some kind of foam too, and maybe that's what you are referring to.
        Maybe he will chime in and describe better, as this is just what I remember off hand.
        Rod
        
        Edits: 10/22/09
        
        Isolation - Showme 17:30:59 10/22/09 (0)
        
        In Reply to: RE: Sorry...:-) posted by Rod H. on October 22, 2009 at 15:29:08
        
        I did personal e-mail with him on this matter and he did say air also, but
        when I saw the material he was using I was curious if he changed his mind. I highly respect his decisions on design. I wonder if the foam was: Parts-Express.com: Sonic Barrier 1" Acoustic Foam w/PSA 18" x 24 ...
        Wazoo had thicker foam as I remember some pics back.
        
        Ray
  - RE: hmmm, that sounds familiar - emsquare 04:28:01 10/22/09 (1)
    Nice... I like the way you did that. Thought out and executed nicely.
    
    In search of musical bliss...
    - thanks - wazoo 05:36:22 10/22/09 (0)
      It evolved from my first attempt at buttressing and elevating my MMGs. As I was building these, I began having flashbacks to some Acoustats I wanted in the late '70s - funny that these look kind of '70s. It occurred to me that keeping the subs physically separated from the panels might be an improvement over what I see manufacturers like Martin Logan produce.
      
      It's been fun fiddling with these speakers and they just get better and better as the project progresses.
      
      "Jazz is not dead - it just smells funny" FZ
RE: One great sub, or 2 good ones? - Jian 13:18:45 10/21/09 (0)
Don't get Velodyne. They will never work with your Magneplanar well. You may get two REL storm, which are about $700 used.
2 - drkielbasa 06:53:25 10/21/09 (2)
Get two powered Velodyne 10" or 12" with the digital processors or equivalent. Various models available in the $600-$800 each range. Run the Maggies full range. Set the subs to cross at about 38hz with 1.6's, 45hz w MMG's or 34hz w 3.6's. Start with a steep even order slope such as -24db/octave. Use the processing to take care of room nodes if needed and fine tune the phase adjustment for integration. For quick placement setup, the reverse listening procedure works well. Place a subwoofer in the listenig chair, then move about the room to find the sweetspot in the area you would like to place them in. Place the first subwoofer there. Then do the same for the second subwoofer while the first is also playing in its new position. Make sure the position allows clearance to avoid interference with the subwoofer venting. If you have trouble finding a sweetspot, then reverse phase by 180 degrees.

Proper setup and integration is what is most important (room/phase/location), not the subwoofer itself (as long as it is of decent quality). The digital processing can help a bit with less than ideal rooms and allow fine tuning of phase. Fine tuning of phase can compensate for less than ideal placement.

I don't know what a "fast" subwoofer is. A decent quality subwoofer will produce minimal harmonics and the quality of low fundamentals from subwoofers varies very little. Your ears will not distinguish even high levels of distortion at these frequencies. The biggest problem with the cheapie powered subs is that the low pass slope of the system is usually less than the claimed -12db/octave and poor cabinet construction may cause unwanted harmonics. I have tested cheap subs that can easily produce a good amount of clean and low bass, but also have resonances audible in the midbass to low midrange. Also, cheap subs are rarely properly vented and dampened.

The ideal setup is that you extend the response of the system down a few notes seemlessly. If your need is that you want "more" bass response, then you'll never be happy unless you get that right before adding subwoofers. If you really need the subwoofer to climb into the 60hz+ frequency range, then you'll need to go with a large dipole or H frame design for better integration w planars.

When listeners claim they really like Brand A over brand B, it is most likely that Brand A was better integrated in the system. Brand B was probably capable of the same if setup correctly.
- RE: 2 - jult52 07:41:10 10/21/09 (1)
  drk - Interesting post but why set the MMG's sub crossover at 45Hz if their lowest response is 50 per the specs?
  - MMG - drkielbasa 09:55:29 10/21/09 (0)
    "In room" response adds gain at lower frequencies compared to standardized measured specs, but for planars, this room effect falls sharply. In a typical room, MMG's can acheive 46hz at -3db. You could run into a case where a significant room null would center around the 50hz range, requiring a slightly higher crossover point, but that would be unusual.
    
    I use a pair of powered 12" subs with my 1.6's crossed at 38hz 36db/octave with an active 3 band parametric EQ available for frequencies below the crossover point. If I replace the 1.6's with MMG's (I own several pair). I find the 45hz point to be ideal. Also, I have a +5db room node at 63hz that I do not want to accentuate. Even with the 36db slope, if I listen to just the subs w/o MG's at normal volumes, I still hear low level harmonics from the subs well above the crossover point, but they are probably low enough in level to be barely perceptible with the entire system running. I think that I have been able to acheive sub integration so that all they do is extend bass response lower, not change it. I have been in many homeowner high end audio rooms, and when subs are in place, they are typically set too loud and too high.
RE: One great sub, or 2 good ones? - David Yost 04:57:51 10/21/09 (6)
With that budget, I would get 4 ULD15's and scatter them around the room. Or, better yet, build yourself an equalized double bass array if DIY is an option.
- Except.... - grantv 09:42:13 10/21/09 (2)
  Velodyne no longer offers repairs, or even replacement parts for the old ULD models. If one dies you're done.
  - RE: Except.... - David Yost 12:15:42 10/21/09 (1)
    I guess that you are right but, aside from an occasional surround or p/s caps, what goes wrong with the ULD's? Also, what else can you buy for <$500 that performs as well and includes crossover and amp?
    - The servo itself. Just ask... - grantv 14:28:27 10/21/09 (0)
      ... me. Mine died, so now I have a non-servo ULD-15. :)
- RE: Yeah, 4 - Travis 07:51:55 10/21/09 (2)
  .
  
  "If people don't want to come, nothing will stop them" - Sol Hurok
  - SWARM (Open in New Window)
  - RE: Yeah, 4 - Bibo01 14:32:45 10/21/09 (1)
    Yeah, I really would like to hear them with my 3.6
    Unfortunately their amp cannot work at 220 voltage...
    - RE: Yeah, 4 - Travis 14:43:16 10/21/09 (0)
      I guess you've already checked with Duke on that problem.
      
      "If people don't want to come, nothing will stop them" - Sol Hurok
RE: One great sub, or 2 good ones? - andyr 00:29:22 10/21/09 (10)
C'mon, DR ... you already know the answer to that one!! :-)) (" Two is better than one ." said the actress to the bishop! :-)) )

Good fast subs for Maggies - IMO, Rythmik Audio servo-assisted subs would be hard to beat. Just over a cubic ft each with (I think?) a 12" driver.

Good luck - your wifey is obviously more accommodating than mine!! :-))

Regards,

Andy
- OB? - grantv 09:40:50 10/21/09 (6)
  How about Rythmik, but an open baffle build if he's willing to do so? Kinda curious about open baffle subs, I think their OB model is still a servo design. One might need a third; a sealed sub, however to cover everything just right. :)
  - RE: OB? - Showme 16:16:46 10/21/09 (5)
    I don't think Rythmik will work.
    
    This driver will work as an OB: BM-18CX38
    
    Ray
    - RE: OB? - grantv 16:24:22 10/21/09 (4)
      The site shows they sell OB plans with their GR research sourced drivers...?
      - RE: OB? - Showme 19:54:10 10/22/09 (2)
        
        In Reply to: RE: OB? posted by grantv on October 21, 2009 at 16:24:22
        
        I found this. Looks like there are systems that require more research.
        These OB speakers could be greater than what I was proposing. GR Research could be the way to go. Here is the model to be available that I think we need to Look at: New Venuette model V2 kit available this November.
        The Super V: http://www.audiocircle.com/index.php?topic=72093.0
        * Site Sponsor
        *
        * Posts: 3878
        *
        *
        o WWW
        Re: OB rigs heard at RMAF 2008
        « Reply #8 on: October 17, 2008, 11:47:48 PM »
        Quote
        Will the open baffle line sources be pure dipole?
        
        Yes they will, and they will play flat to 20Hz. aa
        Logged
        
        * Facilitator
        *
        * Posts: 3878
        *
        *
        o WWW
        Re: New Venuette model
        « Reply #84 on: Yesterday at 07:12:08 PM »
        I am listening to a pair right now. :green:
        Kits will be available as soon as the amps get here. It is looking like it will be mid November.
        Logged
        
        www.gr-research.com
        Ray
        
        Edits: 10/22/09 10/22/09 10/22/09
        
        RE: OB? - grantv 15:09:11 10/23/09 (1)
        
        In Reply to: RE: OB? posted by Showme on October 22, 2009 at 19:54:10
        
        The GR based Rythmik system looks like a good option for a DIY sub build. It'd be interesting to hear someones thoughts (with the resources to build) with some Maggie's.
        
        RE: OB? - Showme 19:34:35 10/23/09 (0)
        
        In Reply to: RE: OB? posted by grantv on October 23, 2009 at 15:09:11
        
        I've tried this, Hoping to get a response from IanLane. I would like to find out if he was still thrilled with his sub.
        
        "No, I don't, Grant ... - andyr 21:16:33 12/15/08 ( )
        * RE: No, I don't, Grant ... - IanLane 12/16/08 17:07:02 12/16/08 ( )
        o Rythmik Audio/ GR Research servo-dipole sub system - Showme 09:01:55 10/23/09 ( )
        o Ian, hi there ... - andyr 18:56:09 12/16/08 ( )
        + RE: Ian, hi there ... - IanLane 19:17:31 12/16/08" /////////////////////////////////////////////////////////////////////////
        
        This is the last I've heard from him from 3/22/08.
        
        "In Reply to: RE: AudioKinesis SWARM: The Ideal Sub System? posted by triamp on March 22, 2009 at 01:53:58:
        This is a pretty good summary of the benefits of a servo based subwoofer system.
        For Joe's information:
        The Rythmik Audio/ GR Research combination allows for an effective operating range between 20 and !60 Hz, with a few choices for the low pass crossover frequency (4th order Linkwitz- Riley). As well as the usual phase/ delay controls there are rumble and general low end filter options, plus parametric eq selections for room modes up to 80 Hz.
        If you build separate baffles for the dipole sub option you can also"tune out" to some degree room modes by changing the orientation of the baffles in the room.
        I would recommend the dipole subs to be run in stereo Push-Pull parallel couples. For the Rythmik Audio servo amp to work with dipole subs the drivers need to be coupled fairly closely. You need two servo amps for stereo operation. A single A370 amp can drive up to four of the OB GR drivers.
        I use two A370 amps with two pairs of the OB drivers crossed at 80 Hz with my old Quads. The bass is deep, tight and powerful and blends very well with the Quads IMHO.
        I would expect a Rythmik/GR system to work just as well with other dipole main systems such as Maggies.
        Both the Audio Kinesis and Rythmik/GR sub systems strike me as absolute bargains for audiophiles, particularly for those in North America."
        The only thing I know to do is drive to Austin and talk to the people at the plant.
        
        Ray
        
        Edits: 10/23/09 10/23/09
      - RE: OB? - Showme 21:12:27 10/21/09 (0)
        
        In Reply to: RE: OB? posted by grantv on October 21, 2009 at 16:24:22
        
        I wonder if a full OB, except for the sub is optimal or partial would be better. GR research OB starts at 200Hz to 2kHz. This is not enough OB for me.
        
        Here are a few comments about this driver BM-18CX38, taken from Diyaudio:
        
        "Hello all....
        
        Just composed a nice post about the viability of the BM-18CX38 as an OB driver and after some distractions it timed out and I lost it all .... Hate it when that happens... A Monday thing I guess.
        
        Anyway... will try to redo now....
        
        The main catalyst for me choosing to work with this driver is rooted in the my original design goals...
        
        To build a passive... medium/high efficiency OB that could be as dynamic as possible... Musical.... practical for most residential environments. It needed to be simple and something you could hook up to just about any competent amplifier... heck receiver and really enjoy what you hear. Liked the coaxial designs horizontal alignment advantage and knew to get the dynamics and bass extension I felt were needed ... a single driver just would not get me there. It had to be a two way at minimum. And to make it compatible with as many sources as possible... it needed to be ALL passive.
        
        What makes for some of the magic is how the woofer sections (the pair I have anyway) measure. Raw free air QTS is .45... mount it on a 1,000 or so sq. inch baffle will shallow wings and you get to .52. Add in the needed and substantial inductance to tilt the midrange down the appropriate amount for passive OB use.. you get to .70 or so. Then there is a FS in the mid 30's. And large area (1,250 sq. mm.) cone and wave guide. Xmax is 4.5 but BL is pretty good out to 6 mm Peak. This is enough woofer to play loud and flat to below 40 Hz. Loud being 105-107 db. The wave guide loading that big 16" diameter cone provides will load the HF CD driver to about 750 Hz. It goes on and on.
        
        Like any design there are compromises and draw backs... including but not limited to a large - substantial baffle, lack of bass below the mid 30's... 6 db or so of the woofers natural efficiency being traded away in the crossover design... and so on. Even with the 6 db loss... you are still in the 94-95 dbw area.
        
        As for the HF CD... it has an FS in the low 500's and is very smooth. As smooth as any Altec... Eminence.... JBL .. Radian or other CD I have ever heard. It is particularly smooth and musical on the lower end. And it really does reach up to above 18K on axis. The key to this thing coming to life is ... as with most speakers... cross over implementation - design.
        
        As for the results... and I have to admit this is still a work in progress.... but this driver really is dynamic... articulate... musical and just plain fun to listen to. I have been listening (and from time to time) designing OB since early high school (like 45+ years) and I have heard few designs of any kind that can compete... again given the design goals. Are these the last word in OB performance... of coarse not... but when you factor in their simplicity, cost and flexibility (no sub... no special electronics.... just a pair of speaker wires to fool with) they are IMHO remarkable. How do they measure... don't know. How do they sound... Like music...LIVE music. Better than they have a right to... but there it is. Are they for every one... heck no. Have they been fun to build ... YEP!!
        
        I will be happy to answer any questions I can... still learning here myself. Hope this has not been too long.
        
        JB Speakerman"
        
        The BM-18CX38 works down below 40 Hz. A lot of unknowns: Crossover, 1000sq" separation from front to back, maybe no WAF.
        
        PAudio BM18CX38
        
        ($995/pr plus shipping)
        
        Choose your free plans here: OB
        
        A good candidate for the upper range would be the ESS AMT1 crossover at 800HZ. Hopefully, in the future there will be builder's plans
        
        http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-600
        
        Description: BM-18CX38 COAXIAL TRANSDUCER
        Size (in.) 18.0
        Power RMS (Watts) 350
        Fs (Hz) 34.0
        Xmax (mm) 4.5
        Sensitivity 1w/1m (dB) 100
        Qts 0.31
        Vas (lt) 432.96
        Magnet Material Ferrite
        
        Ray
- RE: One great sub, or 2 good ones? - Showme 03:53:55 10/21/09 (2)
  C'mon, Andy the http://www.rythmikaudio.com/D15SE.html is what he needs.
  Rythmik will agree. The factory is almost a rock throw from my house.
  - Well, sure ... 15" is always better than 12" but ... - andyr 04:05:29 10/21/09 (1)
    it also mandates a bigger box! :-)) But from my experience with my 12" Rythmik (alas, not mated with my Maggies :-(( ), it goes low enough for me!!
    
    Regards,
    
    Andy
    - RE: Well, sure ... 15" is always better than 12" but ... - Showme 04:51:46 10/21/09 (0)
      I didn't see any difference in the frequency response. I would say the SPL
      would be different. You would need concrete floors for this down firing sub,
      but there are so many other options you can choose from.
RE: One great sub, or 2 good ones? - Leon 23:08:04 10/20/09 (0)
in general, 2 are better than a singleton.
If placed properly you will increase the size of the sweetspot and improve the evenness of response in those lowest octaves.
Some like equalization. Problem is trying to get rid of peaks and dips at the same time across a wide listening area.

Now, the 64,000$ question. How 'bad' is the room. Square? Dimensions evenly divisible by one another? ( say 24' long and 12' wide) or some even multiple? Can you install bass traps in the corners? Music or HT is primary? Single listener or crowd? How BIG is the room in CUBIC feet? This will kind of determine how much sub(s) you will need.

If you can, please google : room mode calculator : this will teach you about standing waves.
If you can, look up Harman White Papers. There is an excellent one on multiple subs.

Post a Followup:

FAQ

Post a Message!

Forgot Password?

Moniker (Username):
Password (Optional):
	Remember my Moniker & Password (What's this?) Eat Me
E-Mail (Optional):
Subject:

Message:	(Posts are subject to Content Rules)

Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:	Automagically notify you when someone responds.

To view your new posting or follow-up, click on the RELOAD or REFRESH button on your browser.