Certified THX Technician Posted July 21, 2008 Share Posted July 21, 2008 To help clarify .... Best Spot to Put Your Subwoofer (single) 1st Choice - Front wall - 1/2 way (center) 2nd Choice - Front wall - 1/4 or 3/4 along length of wall 3rd Choice - Front wall - 1/6 or 5/6 along length of wall 4th Choice - Side wall - 1/2 way (center) 5th Choice - Side wall - 1/4 or 3/4 along length of wall (on side nearest front wall) 6th Choice - Side wall - 1/6 or 5/6 along length of wall (on side nearest front wall) This provides the first 6 spots to try and place your sub based on the first three modal harmonic frequencies which will help provide smoother bass response. One of these should work in almost all situations. 1 Quote Link to comment Share on other sites More sharing options...
DU73 Posted July 21, 2008 Share Posted July 21, 2008 THX – your posts are very informative and very helpful to many I’m sure and can’t wait for the weekend where I know it will make great reading. Although, I do have to agree on BigDaddy, not everyone has a dedicated HT room, and many of us has to do what we can with the space given to us and not to upset other family members. Question, my sub is front firing, or whatever you call it, and is positioned in front in line with my mains about a meter from the right hand corner, front wall in approx 3.3 meters long with my mains on either end. Sub is approx 1 meter away from corner, are you saying that I should put my sup on its side so the woofer is facing the wall? Quote Link to comment Share on other sites More sharing options...
bigdaddy Posted July 21, 2008 Share Posted July 21, 2008 Ok I'll buy that. Quote Link to comment Share on other sites More sharing options...
Certified THX Technician Posted July 21, 2008 Share Posted July 21, 2008 Question, my sub is front firing, or whatever you call it, and is positioned in front in line with my mains about a meter from the right hand corner, front wall in approx 3.3 meters long with my mains on either end. Sub is approx 1 meter away from corner, are you saying that I should put my sup on its side so the woofer is facing the wall? What I meant was if you cannot put your sub on the front wall with the mains and center, and you have to put it on the side wall...if you choose to put it at 1/3 or 1/4 the length of the wall, put it on the part of the wall that is closest to the front wall ...the side of the wall, not the side of the sub. Sorry for the confusion. The sub's driver, if front firing, should face you no matter where you put it ...same direction as your speakers do. Hope that clears things up. And I realize everybody does not have a dedicated room etc ...all I'm saying is here are the principles so that you can try to apply them to your space. The more you can adhere to the standards, the better your sound will be. Even a cheapo two speaker stereo system can sound better by applying the standards, toeing in the speakers towards the listening position, placing at proper height, proper sound levels etc ...all the THX standards can be applied to any type of system to make it sound it's best. I haven't even begun to dig into Room treatment..things you can do to eliminate echoes, reflections ...where to put bookcases, what kind of seating, flooring and materials are best etc to make your system sound better..... I'll save that for another day : ) 1 Quote Link to comment Share on other sites More sharing options...
Certified THX Technician Posted July 21, 2008 Share Posted July 21, 2008 Please direct questions to the Ask a THX Technician post ..... we are clogging up Steve's original post and getting off topic (which is partly my own fault).. I love to educate, and can take criticism as well ....I'm just here to make your gear sound it's best! 1 Quote Link to comment Share on other sites More sharing options...
DU73 Posted July 22, 2008 Share Posted July 22, 2008 What I meant was if you cannot put your sub on the front wall with the mains and center, and you have to put it on the side wall...if you choose to put it at 1/3 or 1/4 the length of the wall, put it on the part of the wall that is closest to the front wall ...the side of the wall, not the side of the sub. Sorry for the confusion. The sub's driver, if front firing, should face you no matter where you put it ...same direction as your speakers do. Thanks Robin - I will leave as is. My tv is on a stand/cabinet and therefore the sub would need to stay where it is, as if I put it on the side wall then the sub driver is not facing the same direction as my mains. I apologise for hijacking the original post. Quote Link to comment Share on other sites More sharing options...
Certified THX Technician Posted July 22, 2008 Share Posted July 22, 2008 Thanks Robin - I will leave as is. My tv is on a stand/cabinet and therefore the sub would need to stay where it is, as if I put it on the side wall then the sub driver is not facing the same direction as my mains. I apologise for hijacking the original post. The sub's driver should face the listening location, as do the speakers. if the sub is on the side wall, it's driver will face inward towards the room even though your mains will face perpendicular to that ..... See my previous post above on the 6 spots to put your sub ...I just checked my training notes and made some adjustments. If you move your sub into one of these positions it will help with the standing waves and even out the sub response. even if you have to move it a foot over, it will make a difference. Quote Link to comment Share on other sites More sharing options...
Certified THX Technician Posted July 22, 2008 Share Posted July 22, 2008 Gonna start a new thread on Subwoofer placement based on THX standards.....made some adjustments to my numbers in my above posts after referencing my notes .... Please direct any sub questions to the new Sub thread. Thx 1 Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 22, 2008 Share Posted July 22, 2008 The old rule of thumb was "just stick it in a corner"....this is however, the WORST spot to put a subwoofer. Based on what? My experiences AND measurements have indicated quite the opposite actually. [] The theory on modal behavior to which you refer is based on simplistic models that don't hold true in the real world. Where do we ever see a perfectly sealed rectangular prism for a room? Windows, doors, adjacent open rooms, closets, HVAC, etc... will all dramatically influence the modal behavior. I'm not saying that the corner is always the best spot, but I am saying that it can be a best spot...especially considering that you can get 6dB reduction in distortion due to boundary gain. I am saying though that the blind recommendation of putting the subwoofer at the center of walls is not going to guarantee a best solution. Heck, even the idealistic modal theory supports the notion that center placement isn't necessarily the best! This is Boundary Gain, and you do not want it because it is boosting the bass frequencies from what the reference level should be... Total BS. Boundary gain gives you more output for the same amount of distortion...or if you use EQ to bring the system back to a flat frequency response, then you end up with less distortion for the same SPL. Considering that subwoofers are the highest produces of distortion in a sound system, it only makes sense to take every effort possible to decrease the distortion they create. It is entirely trivial to deal with the tonal balance shifts from boundary and room gain. Quote Link to comment Share on other sites More sharing options...
bigdaddy Posted July 22, 2008 Share Posted July 22, 2008 Klipsch's RT-12D sub is designed to be in a corner. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted July 23, 2008 Share Posted July 23, 2008 To expand on Dr.Who's post... putting a sub in the corner and then using a tool like the RoomEQ wizard ( free when you join the HT shack ) and a Behringer Feedback Destroyer... allows you to set extremely fine notch filters ( 1/60th octave ) to reduce peaks. You have the best of both worlds... flatter FR @ seat and more output for the same amount of power into the transducer. Lowering the amount of gain needed on the sub, you have just reduced distortion VS. other placement in room. The types of distortion reduced are IM distortion, Bl distortion, CMS induced ( suspension ) distortion, thermal compression changing FR... etc. Quote Link to comment Share on other sites More sharing options...
Certified THX Technician Posted July 24, 2008 Share Posted July 24, 2008 Klipsch's RT-12D sub is designed to be in a corner. And it is not THX Certified ...and for good reason ....I will try to address this in my other thread on Subwoofers and proper placement. 1 Quote Link to comment Share on other sites More sharing options...
bigdaddy Posted July 24, 2008 Share Posted July 24, 2008 Ok whatever. Neither are my Klipsch Fortes but I'll put them against plenty of speakers that are. I'll grant the speakers that are certified by THX are capable but I'll also add there are lots of speakers out there that are as capable and choose not to PAY to be certified by THX. It's a marketing tool. THX does not do this out the kindness of their heart. Rather it's done for profit period. The pro media 2.1 setup is THX certified does that make it better than my Fortes? Not on your life. Quote Link to comment Share on other sites More sharing options...
Certified THX Technician Posted July 25, 2008 Share Posted July 25, 2008 Ok whatever. Neither are my Klipsch Fortes but I'll put them against plenty of speakers that are. I'll grant the speakers that are certified by THX are capable but I'll also add there are lots of speakers out there that are as capable and choose not to PAY to be certified by THX. It's a marketing tool. THX does not do this out the kindness of their heart. Rather it's done for profit period. The pro media 2.1 setup is THX certified does that make it better than my Fortes? Not on your life. I think the point is being missed here... that sub placement, along with room treatment, seating position etc are keys to having smooth bass response for the listener...NOT how good the sub is etc ...The best sub in the world, with perfect frequency response, will still cause problems in any room if not placed properly, and the room treated properly etc ....THX Certified gear means it was manufactured to meet rigorous engineering requirements and will perform up to THX standards at Reference levels with minimal distortion etc ... The only reason most people think it is a marketing tool is because they really don't know anything about it (either did I before I was certified). Yes, there is some gear that will hold up to THX engineering and performance specs that did not attempt to pass THX certification, but most won't because they were not built and engineered from the ground up in the first place to meet the THX performance standards. THX actually works with the manufacturers to build their products. Most of the specs are just very good engineering and design principles, but usually are not adhered to by manufacturers due to their own beliefs and due to manufacturing costs. However, many products that are brought in for testing, expecting to pass due to the "greatness" of the product, simply cannot meet the standards when push comes to shove and they do not pass the certification tests. It's up to them at that point to further engineer the product to meet the requirements or to simply sell it as is. 1 Quote Link to comment Share on other sites More sharing options...
bigdaddy Posted July 26, 2008 Share Posted July 26, 2008 Klipsch's RT-12D sub is designed to be in a corner. And it is not THX Certified ...and for good reason .... The point was you made this statement and it's really kind of rediculous. You can make any claim you want but THX certification is a marketing tool companies use. Yes it does require a certain level of performance. I've never denied that. But the above statement gives the impression that the RT-12D sub is in some way inferior. Nothing could be further from the truth. It was engineered by Klipsch(let's admit they know something about speakers) to be used in a corner for good reason. Here are a couple of quote from a well known sub builder Mark Seaton(Builder of the Seaton Submersive) Having experience in the extreme pro audio side (especially subwoofers), and having put 4, 16Hz capable subwoofers into George Lucas's private home (not The Ranch), I'll add my experience on the matter. Thank you for the detailed explanation of your initial impressions. As you correctly noted, you have a rather large/open room, and for maximum LF output, a solid corner would very likely provide a significant improvement. Obviously he disagrees with the theory that a corner is the worst place to put a sub and I'd say he knows what he is talking about. Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 26, 2008 Share Posted July 26, 2008 Hey, did you guys know that Klipsch (specifically I think Roy Delgado) pretty much wrote the THX Ultra2 specification?!? [] Theonly reason the RT-12D isn't going to be Ultra2 certified is becauseit'd take more than one unit to achieve 130dB at 30Hz in a 3000 cfroom. A single RT-12d is actually a better performer than a singleKW-120. Also, the RT-12d does not need to be in a corner...it's formfactor is mostly driven by aesthetics (it's easier to tuck it into thecorner out of the way). Quote Link to comment Share on other sites More sharing options...
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