It is currently Wed Nov 22, 2017 8:09 am

All times are UTC-05:00




Post new topic  Reply to topic  [ 21 posts ]  Go to page Previous 1 2
Author Message
 Post subject: Re: 2x Tuba 18 build
PostPosted: Fri May 26, 2017 5:29 pm 
Offline

Joined: Tue May 23, 2017 8:21 pm
Posts: 26
Grant Bunter wrote:
I don't think DSP will solve the problem BTW.


I also don't think it will solve anything. But maybe I can move the problem around and use it to my advantage.

The sides of the room are the only places I want bass. Right now it's strong in the middle, medium on the sides, and dead in the two spots between.

The center opens to a hallway which carries sub bass throughout the whole house. Nobody ever hangs out in the middle; there's no seating there. Having the most bass here is my main issue.

If I can move the cancellations around with phase/time delay, I'll be more than happy. E/g weaker in the middle, stronger on the sides.

Heck, reversing polarity on one side might get me part way there lol.


Top
   
 Post subject: Re: 2x Tuba 18 build
PostPosted: Sat May 27, 2017 4:00 am 
Offline

Joined: Mon Nov 28, 2011 11:12 am
Posts: 5647
Location: Ilfracombe Queensland Australia
djamps wrote:
Grant Bunter wrote:
I don't think DSP will solve the problem BTW.


I also don't think it will solve anything. But maybe I can move the problem around and use it to my advantage.

The sides of the room are the only places I want bass. Right now it's strong in the middle, medium on the sides, and dead in the two spots between.

The center opens to a hallway which carries sub bass throughout the whole house. Nobody ever hangs out in the middle; there's no seating there. Having the most bass here is my main issue.

If I can move the cancellations around with phase/time delay, I'll be more than happy. E/g weaker in the middle, stronger on the sides.

Heck, reversing polarity on one side might get me part way there lol.


Reversing polarity in one cab is simply going to cause cancellation across the entire band pass for the subs, so that's a no go.
Also, changing phase via DSP won't really alter the problem, in that, the physics of sound waves means regardless of how much you phase shift via delay, the wave still occurs.
Phase is frequency dependant, so you end up in a catch 22 unless the only frequency you try to address is that at the crossover point between subs and tops.

You also can't change the physics of sound, in this case, the fact that sub bass is omnidirectional.
It simply goes everywhere.
I don't think you're going to change the sub bass to being "only on the sides", or "not down the hall" due to this (but would be happy to hear you managed this, and how you did it).

I've had this problem for you trolling through my head all day.
The problem of cancellation due to inadequate separation can somewhat be addressed, by using DSP to high pass from say 50Hz. Why 50Hz? This is where the T18 starts to fall off anyway, but it will also reduce whatever cabin gain is happening below that point if you use a steep slope filter.
Kick drum thump is 50-80Hz. The lowest bass notes will still be heard via 1st harmonics.
It doesn't change the omnidirectional nature of sub bass, but it will reduce some of the longest travelling waves (due to frequency), reducing the effects in the hall.

This isn't something I would normally suggest, but yours seems a unique situation.
Certainly worth a try...

_________________
Built:
2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's, 2 x 28" 3012lf loaded underway.
3 x WH8 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...


Top
   
 Post subject: Re: 2x Tuba 18 build
PostPosted: Sat May 27, 2017 7:02 am 
Offline

Joined: Wed Jul 30, 2008 10:18 am
Posts: 582
Location: Kankakee, IL
Well this is probably out there, but what about building a third t-18, sticking it in the hallway, and purposefully reversing its polarity, ala noise cancelling headphones?

_________________
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!


Top
   
 Post subject: Re: 2x Tuba 18 build
PostPosted: Sat May 27, 2017 12:48 pm 
Offline

Joined: Tue May 23, 2017 8:21 pm
Posts: 26
Rich4349 wrote:
Well this is probably out there, but what about building a third t-18, sticking it in the hallway, and purposefully reversing its polarity, ala noise cancelling headphones?


Interesting idea. It is possible, the hallway has ledges but not as much height so it'd have to be low profile, perhaps a 12" T18

I'm purchasing a minidsp 2x4 to get my portable rig out of the room, so the DSP is there whether it helps or not...if I can shift the cancellations around a bit with time delay, at least for the frequency range I care about, it might be all I need to call it done.

This is not supposed to be a SQ contest or chest thumper; it's for background music primarily, with occasional louder volumes for parties, football games, ect. At higher volumes in the cancellation zones, you can at least feel the floor moving :lol: I keep remembering these are only 8" drivers in such a large room causing so much raucous. Hats off for Bill's designs working even where they shouldn't. :clap:


Top
   
 Post subject: Re: 2x Tuba 18 build
PostPosted: Sat May 27, 2017 6:42 pm 
Offline
User avatar

Joined: Sun May 17, 2009 10:12 pm
Posts: 1375
Location: Central FL ~Authorized Builder
djamps wrote:
Interestingly, if I turn the tuba around and aim it at the corner of the room, it get's REAL boomy/muddy with this setup. Playing them forward in the same direction as the mid/high range speakers sounds really nice, even on the low end...


Was this test done in the current main room? If not turn those subs into the wall. If it was done in the main room and you have the ability to highpass, experiment with that, you will have more spl to work with and can cut some of the subbass boom you described.

Secondly, for more spl at your room sides, try moving them from their current location further down the ledge (since this is where they have to be) to see if you get more spl where you want really want it.

_________________
"Things happen, but music stays in your blood forever~." bf

InfraCoustik
Consulting/Design/Fabrication
Authorized BF Builder
http://www.infracoustik.com/
info@infracoustik.com


Top
   
 Post subject: Re: 2x Tuba 18 build
PostPosted: Sun May 28, 2017 12:53 am 
Offline

Joined: Tue May 23, 2017 8:21 pm
Posts: 26
Drey Chennells wrote:
djamps wrote:
Interestingly, if I turn the tuba around and aim it at the corner of the room, it get's REAL boomy/muddy with this setup. Playing them forward in the same direction as the mid/high range speakers sounds really nice, even on the low end...


Was this test done in the current main room? If not turn those subs into the wall. If it was done in the main room and you have the ability to highpass, experiment with that, you will have more spl to work with and can cut some of the subbass boom you described.

Secondly, for more spl at your room sides, try moving them from their current location further down the ledge (since this is where they have to be) to see if you get more spl where you want really want it.


The boomyness happened in the smaller room I was testing in. Unfortunately I cannot move them on the ledge because of lighting (old school flourescent) that starts a few inches away.

Tonight we had a pretty big party. The DBX voltage limited the subs around 30 volts. 30+ people in the room, nothing but compliments. "Over easy" actually sounded best with the limiter getting hit pretty hard. You could still have a converstion while the bass was deep and strong.

Cancellations and all, I'm really impressed....


Top
   
Display posts from previous:  Sort by  
Post new topic  Reply to topic  [ 21 posts ]  Go to page Previous 1 2

All times are UTC-05:00


Who is online

Users browsing this forum: Lustyik and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
banner
Powered by phpBB® Forum Software © phpBB Limited