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Discussion Starter #1
Has anyone tried making the BBC A10 bass traps? I have a massive 60-65 hz bass null at the seating position in my room (which makes sense given the 18.5' room length). The A10 trap is designed to absorb right around those frequencies.


Here is the PDF describing it. Last couple of pages:
http://downloads.bbc.co.uk/rd/pubs/reports/1992-10.pdf


I'd love to hear others experiences before I go and make a bunch of them.
 

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Quote:
Originally Posted by snurf /forum/post/20900486


I have a massive 60-65 hz bass null at the seating position in my room (which makes sense given the 18.5' room length). The A10 trap is designed to absorb right around those frequencies.


I'd love to hear others experiences before I go and make a bunch of them.

A bass trap approach will very likely help the LF quality in your room, and most likely significantly. However it may not help with the null in which you're describing. Absolutely pursue the route of bass trapping, but first, go for the low hanging fruit. Experimenting with sub placement, listener position, or both is the approach that will help you the most right now. Ultimately, a sub system, utilizing multiple subs spaced within your room will mitigate the a large percentage of LF aberrations.


So finally, multiple subs, with time and frequency equalization, combined with bass traps will be the holy grail. And that's that that difficult to achieve, even with a relatively modest system. Additionally, bass traps tighten things up by addressing modal ringing, LF hangover,..note to note. So general perceptions are of a much more delineated bass line and details due to knocking down the bass ringing of the rooms characteristic response.

This is one work of Floyd Tooles,..good stuff.

This is helpful.

This is Ethan Winers outstanding paper on rooms and acoustics, with significant aspects of bass traps(of which few individuals have more knowledge). Very, very good, and he's a contributor here at AVS.



Good luck
 

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Discussion Starter #4
I've got 2 subs right now (2 dts10s). My aesthetic constraint is that I want them behind the screen, which is probably whats causing a lot of my problems. I've tried flipping them all of the different orientations I can behind the screen (that was not a fun evening), but the lengthwise mode remains pronounced. If I move my seats up by 3 ft, it gets better, but that doesn't really fit with the rest of the room


I think adding a third smaller sub would certainly help, but additional trapping seems cheaper and more attractive



There also isn't a lack of bass in general, and if I move the spl meter forward or backward 4' from the seating position, I gain 15db at 63hz o_O


Since the bass spl is so high on the back wall (+15-20db), i'd think a pressure based membrane absorber would be ideal.


To add a bit more info: I have 3 super chunks up front (2x wall/wall, 1x ceiling/wall). No other traps. I've got a Behringer FDP to eq the subs, but I don't want to go the eq path until the room response is a bit flatter.


I'll go read up on the gearslutz threads. Thanks!
 

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Snurf:


Have you tried adjusting the phase of one sub relative to the other? Also, adjusting the "distance" of your subs in your receiver/processor. It may be an interaction between your subs themselves, or or subs and your mains. Also, tweaking your crossover frequency may help with that null.


I just recently added a second sub, and was amazed at the difference adjusting phase between subs (one of my amps has a continuously variable phase between 0-180), distance (to adjust "phase" of the sub array as a whole), and crossover to mains frequency had in smoothing out a few serious frequency dips across my entire front listening position.


All you need is REW and some patience.



Best,

C.
 
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