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Everything posted by jcr159

  1. So to keep this thread going... and to continue my education... the typical recommendation from AVRant, and one i agree with overall is to go with 2 or 4 subs in opposing corners, or midpoints of the walls. You are then calibrating to set level and delay (phase) relative to the primary, or group of primary listening positions.... This is basically the Toole recommendation based on his research, and generally agrees with Geddes as well (though Geddes prefers 3 or more and locates within the 3d space, so you are dealing with the height modes as well...) All that said, are these techniques achieving any sort of "Active trapping", or is it more of a create a "uniform wavefront" that is helping? or something else? If the multi sub approach is just presenting improvements to room nodes with placement and uniform wave front generation, i'd expect better seat to seat average response by looking at a frequency response graph. However, if it isn't providing any sort of "trapping" behavior, i wouldn't expect a better result (probably just "different") in a waterfall decay measurement. Where adding "trapping" behavior I'd expect better waterfal measurements, less ringing, etc... hoping i'm making sense, lol. straighten me out if not! -j
  2. I agree RIcci, is it because it is super difficult to figure out except by trial and error placement and tuning?
  3. Good stuff SME... right now I'm running Paradigm studio 60's and the matching LCR center, but when I build out the theater was thinking about changing up to the sierra RAAL's... I'm torn between bookshelves and towers since I'll only be about 8-9 feet, but the space will be open to about 5200 cu ft total (no real doors to other areas). Makes me think I'll need some driver area than the bookshelf models have.... but the towers are so much pricier
  4. you guys rocks, thanks to all... my credit card company is going to be happy too...
  5. Ok, thanks ShadyJ. I was thinking along the same lines... Room will dominate what i hear a lot, but if the reproduction is crap from the sub itself, no overcoming that... to that end though, the room will need treated properly to get the best sound quality and i haven't worked out that plan yet. as for 3 subs, i actually was planning 2 or 4, as my reading so far has shown that i'm more likely to get a good result when planning out ahead of time. in other words, if i need to design locations into the room layout without have a built room to test first, i'm less likely to screw it up by sticking to 2 or 4 subs... since 4 might take a bit too much real estate for spousal acceptance, i was leaning toward 2 knowing that i'm leaving something on the table... one will be located behind an acoustically transparent screen. Maybe i'll get creative and build the second into some furniture in the back of the room... i'd love to double up on 18's and put 2 in each enclosure dual opposed, but then maybe i should just go to a 21 or 24... lol -j
  6. thanks for all the well crafted discussion. still getting my head around everything and learning here. I think one of the takeaways i'm getting is that if quality and accuracy of reproduction is critical, it is probably best to design for more "sub" than i need to hit the volume levels i'm looking for... for me it will be a given that i'm building 2 subs, placing them mostly optimally to get the best coverage across the room. but if i'm reading things correctly, and need say an average 15" dayton driver in each box (sealed will be my choice for size reasons most likely) to hit reference, I may be better off building a pair of 18" subs that don't need to be pushed as hard. that seems to make sense to me, but i don't know... If that is correct, and one "over designs" the system to only use a small part of the output capability, will it keep things more accurate as a result? i.e. - only using 30%-50% of xmax to acheive the output desired. If doing that, does it ensure better quality output by eliminating the non-linear distortions, inductance and power compression, etc? Sorry for so many questions, but trying to learn the best i can. It seems like the only advice i can get on AVS is to buy a 10,000 gigawatt amp and buy the driver with the biggest xmax to get output... Seemed like it is a bit more nuanced then that to get a good result, and appreciate the education i'm getting here. thanks again, -j
  7. Ok, so found this... looks like i need to school myself a bit. http://www.audioholics.com/loudspeaker-design/audibility-of-distortion-at-bass
  8. Are you saying that the ported designs generally have lower distortion?(presumption on my part is that would be above tuning)...
  9. Yeah, my bad... I was reading the sb13, not pb13..... should be apples to apples there
  10. Thanks for the response, but I was reading the DVD pb13 ultra sealed results against the ultimax 18-22 which I thought was also sealed... I may have read the wrong thing and will double check, but thought I was comparing all sealed including the pb13... maybe the confusion was that the "on" should stand for "ported"?
  11. Thanks for the reply. I gravitate towards "accurate" I think.... I like my paradigm studio towers.... I like my Etymotic headphones, so I'm likely to prefer the most accurate and least distorted bass... that said, I'd prefer enough headroom so whatever I end up with doesn't need to struggle to hit peaks... that "should"? Lower distortion and bad sounds overall I think... I think the kicker for me in all of this was the realization that some of the popular DIY drivers are probably popular for cost and power/output reasons more than sounds quality reasons.... All that said, I realize the slight ridiculousness of talking about bass/sub-bass sound quality since the human ear is much less sensitive to it... on top of that the room sizes(small room acoustics) are probably so dominant that driver and sub design may only account for a fraction of what you are hearing anyway, but figure if I'm going to build or buy, why not get something good... lol
  12. hopefully this hasn't been asked here before, I couldn't find anything.... What makes one sub "sound" better than another? vague question, and i'm sure going to cause a flame war... at least it would on AVS, hence asking here... I know all the data and research about how much less sensitive we are to distortion at lower frequencies, etc. So I don't exactly need pointed in that direction. Here's where I am... Was planning to go DIY for my theater build out that is in the design stage (the whole basement is actually...) The original plan was to DIY 2 or 4 subs depending on size and layout. I'll be using opposing corner or opposing wall placements as well which line up roughly with the harman and toole research. not looking for boosted output, but more even room response in that sense. based on the room volume, i'll be in the SVS PB 13 ultra or 16 size range, but know i can build some sealed 18's or heck even the SI 24's sealed for smaller and less money than that. What i'm looking for is whether there would be any sound quality difference to be had by picking different drivers or from an SVS (or HSU/outlaw/PSA/etc.) route. I'm a data guy to be honest... so don't hit me with subjective hooey gooey... This is data-bass after all where we look at charts and numbers, etc... To end cap things, I created this post because on a whim i was comparing the distortion measurements here (thinking it was an indicator of sound quality in some respect at least but not sure how much). I was looking at the Dayton UM-18-22 i think sealed vs. the SVS PB SB13 Ultra which is quite expensive, and was shocked how much less distortion was measured on the Dayton. I didn't think that particular Dayton was considered fantastic either. It shocked me... I then went looking at the Stereo Integrity 18 models (HT and HST) and was shocked how much more distortion they had as well... So I then wondered if any of the tested drivers could do less than 5-10% distortion down to 20Hz and below, and clicked on the SI 24. it hit that mark easily. Made me think of the adage "there's no replacement for displacement". So now here I am asking for advice, lol. I know the distortion numbers don't matter as much in the bass/sub-bass as they do in the midrange as the ear is much less sensitive, but if i can build and get significantly better quality bass out of some dayton parts than a pb13, i just saved a lot of cash to go buy a front stage... Thanks for any thoughts! -j Edit: changed to reflect I was in fact comparing the SVS SEALED not PORTED... I was comparing Sealed to Sealed...
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