Author Topic: Sub strategy  (Read 18064 times)

Offline Werd

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Sub strategy
« on: July 02, 2015, 02:55:00 PM »
Been using a dual sub configuration lately. I've got one Nola sub straight  right in front of me. I am using the second along the wall behind me and over my left shoulder.

I am beginning to understand the problems with subs and placements. I think I might have solved a problem in my room using dual subs. In fact it sounds pretty snazzy.

The natural tendency is to put both subs on the ground. This is false and bad practice IMO. I've never been able to make it work. Subs on the ground are used for ambience. The problem with placing subs on the ground is it creates to many nodes by moving bass along the ground. Even if they are are used out of phase.

Another reason for using a sub is to enhance resolution in the bottom end. The way to do that is by applying a subwoofer lifted off the ground. A good height is the distance between the woofers on your mains. Or the distance between the midrange and woofer. The thing that isn't discussed ever with subs is Subs can be used to beam a signal much like a midrange and tweeter. When you take the sub off the ground it begins to be come less ambient and takes on more beam signal. If this wasn't possible there would be no bass resolution in the sweet spot from your mains. Mains woofers can direct bass and so can subs off the ground.

So I got a sub lifted  in the sweet spot and I got a sub behind
me creating ambient room info.

So subs off the ground for resolution and subs on the ground for ambience. That's in my room anyways.  :thumb:
« Last Edit: July 02, 2015, 03:02:48 PM by Werd »
Nola Viper Reference iii, Nola Blue Thunder Subs, Chapter Couplet 400s, Chapter Précis 250 integrated set to pre, Bryston BDA2/BDP1.
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Offline Werd

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Re: Sub strategy
« Reply #1 on: July 02, 2015, 03:12:26 PM »
Also if I am using only one sub and I want ambient info I would use it behind me only. If the sub is going anywhere near the sweet spot it comes off the ground for resolution. Trying to retrieve ambient room info with a sub near the mains in front of me is really hard to do. Sub placement on the front wall is for resolution only and off the ground. That's been my findings.  :thumb:
Nola Viper Reference iii, Nola Blue Thunder Subs, Chapter Couplet 400s, Chapter Précis 250 integrated set to pre, Bryston BDA2/BDP1.
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Offline satfrat

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Re: Sub strategy
« Reply #2 on: July 02, 2015, 06:40:05 PM »
I too raised my subwoofer off the floor with a sub stand that I built from 2" thick oak. I placed the stand next to my main Lorelei with the down firing woofer 30" off the floor, just below my midwoofer. The sub blends in nicely and just disappears.
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Offline Werd

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Re: Sub strategy
« Reply #3 on: July 02, 2015, 09:03:12 PM »
Exactly  :thumb:
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Offline BobM

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Re: Sub strategy
« Reply #4 on: July 03, 2015, 04:46:47 AM »
My downfiring REL Strata III sub is turned upside down, so it is now upfiring and I have a heavy board on those upturned feet with some weight on top of it. It is placed right in line with the speakers, away from the wall.

Much better resolution and easier to blend, though it had to be turned up a wee bit now.

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Offline jimbones

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Re: Sub strategy
« Reply #5 on: July 03, 2015, 07:09:33 AM »
so mine is pretty much on the floor. How high should I raise it.
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Offline Werd

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Re: Sub strategy
« Reply #6 on: July 04, 2015, 11:23:47 AM »
so mine is pretty much on the floor. How high should I raise it.

A little higher than the bottom driver on your mains.
Nola Viper Reference iii, Nola Blue Thunder Subs, Chapter Couplet 400s, Chapter Précis 250 integrated set to pre, Bryston BDA2/BDP1.
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Offline Werd

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Re: Sub strategy
« Reply #7 on: July 04, 2015, 06:29:35 PM »
Actually I would go as high as you can go.  Make sure the woofer is facing you.
Nola Viper Reference iii, Nola Blue Thunder Subs, Chapter Couplet 400s, Chapter Précis 250 integrated set to pre, Bryston BDA2/BDP1.
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Offline Werd

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Re: Sub strategy
« Reply #8 on: August 21, 2015, 04:42:13 PM »
So as it turns out two subs and their placement pretty much dictates where the placement of the mains. IME in my room not vice veraa.

Getting the front sub off the floor for resolution requires the front sub to be off from centre from a point down from the middle of the wall, which then requires a main speaker on each side of the sub. This puts the sweetspot not in the center perfectly in the room but in a corner. While still having the mains run parallel with the walls . Basically using a corner of a room with the rest of the room open behind and to the left (in my situation) wide open.
What this does is sets up the use for the second sub placed on the floor behind my left shoulder along the side wall. It makes the room sound larger from a length and width persepective which i really like for ambience.

Putting a your speakers equally distanced with a 2/3 room placement (concert bowl) really screws with the ambience of the rear sub and reaolution of the forward sub. I will never do that again placing speakers with equal distance from side walls using subs.
Nola Viper Reference iii, Nola Blue Thunder Subs, Chapter Couplet 400s, Chapter Précis 250 integrated set to pre, Bryston BDA2/BDP1.
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Offline rollo

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Re: Sub strategy
« Reply #9 on: August 22, 2015, 05:09:35 PM »
Si Senor I have been recommending that for years. To be precise get the center line of the woofer off the floor to 20% of floor to ceiling height. Meaning if clg. is 8 ft then 20% of that is the height.
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Offline Werd

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Re: Sub strategy
« Reply #10 on: August 22, 2015, 06:14:10 PM »
You don't want the front sub (resolution) to be at the same height as the bass drivers on your mains. If you can avoid it.
Nola Viper Reference iii, Nola Blue Thunder Subs, Chapter Couplet 400s, Chapter Précis 250 integrated set to pre, Bryston BDA2/BDP1.
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Offline _Scotty_

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Re: Sub strategy
« Reply #11 on: August 22, 2015, 06:22:55 PM »
Moving the sub from the floor/wall boundary to the somewhere on the wall itself changes the room boundary loading on the sub and may also change the room gain and the pattern of standing waves in the room resulting in a perceived improvement in the quality of the bass.  
 A frequency below 125Hz that was over emphasized at the listening position could be reduced in amplitude and the bass would seem to have better definition when the sub is relocated.
 You have changed the sub-woofer loading from roughly a Quarter Space loading to approximately a Half Space condition.
See link, https://www.trueaudio.com/st_spcs1.htm
More useful information
https://www.trueaudio.com/st_index.htm

Here is the approach I use implemented with a sub in the rear and a sub on the side wall. Digital delay is provided by a QSC DSP 30 Processor
See Link, http://vbn.aau.dk/files/12831869/AC-phd.pdf
Scotty
« Last Edit: August 22, 2015, 06:25:13 PM by _Scotty_ »

Offline Werd

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Re: Sub strategy
« Reply #12 on: August 22, 2015, 08:02:23 PM »
I put your method and it's science on my book marks.   :thumb:

The problem i have with the science (and its good) they don't identify the problem and what it means to the system sound. They don't understand the problems. I have yet to read a paper that acknowledges putting subs on the floor is used to enhance the ambience. Which basically means loading the room. Putting subs on the floor to improve resolution is a failed concept imo. No subs should be on the floor in front of you. I am absolutley certain of that. I have yet to read that anywhere. So unless there is anecdotes to clarify -using subs on the floor and this is the science how to do that. This is only half information. They need to explain what loading does and how it creates a room and enhances ambient effects of the soundstage to the person listening to it.That is never said.

So this is what happens. People will do what they read and they will likely include a forward sub and then they are back to square one. Because that sub on the floor in front is the bane of all hi-fi. It wrecks the resolution of the soundstage and it cancels ambient nodes behind you. And that is if they do it right. They are better off fucking it up and getting lucky with a sub placement that at least gives you somewhat decent rear room loading.
« Last Edit: August 22, 2015, 10:49:20 PM by Werd »
Nola Viper Reference iii, Nola Blue Thunder Subs, Chapter Couplet 400s, Chapter Précis 250 integrated set to pre, Bryston BDA2/BDP1.
Torus RM-20 240v

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Offline Werd

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Re: Sub strategy
« Reply #13 on: August 22, 2015, 08:43:22 PM »
There is one thing that i've noticed regarding room treatments and sub placements papers. etc. There is inheritant need to fix a bad room with subs and room treatments. That is audio sales and what they have done to audio playback to make a pitch. My personal imo is to embrace the nodes and room peculiars. Its those things that get the toe tapping.  You start cancelling nodes and using defusers you have lost what is great about the room. You have lost the beats. It becomes more sterile.

That is my personal opinion and it is not necessarily correct. People have their own way of identifying to their systems and that is cool. I have no problem with that. But if people come over and your system doesn't make them want to dance or groove, then there is a problem.  You should have excellent sweetspot resolution with a good groove that makes people want to party.
Nola Viper Reference iii, Nola Blue Thunder Subs, Chapter Couplet 400s, Chapter Précis 250 integrated set to pre, Bryston BDA2/BDP1.
Torus RM-20 240v

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Offline Werd

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Re: Sub strategy
« Reply #14 on: August 22, 2015, 11:07:15 PM »
Another interesting thing i have noticed. It also seperates the 2 goals apart. That being resolution and ambience in subs. When dialing in cross overs use the highest crossover point on your sub for resolution then start moving back down to a lower crossover point. I have found if the sub is off the floor anything over 100 to 200 hz cross over is where you will probably end up.

If you are using a sub for anbience start at the lowest (probably around 40hz) and then move up to get a good sensation of the room. Mine is much off 40hz. This is IME.
Nola Viper Reference iii, Nola Blue Thunder Subs, Chapter Couplet 400s, Chapter Précis 250 integrated set to pre, Bryston BDA2/BDP1.
Torus RM-20 240v

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