Multiple Subwoofer Placement

[cjfrbw]

I intend to measure eventually, but for now, it seems to be working. Hail the Subjectivist! Down with the Subjectivist!

 

[FrantzM]

I intend to measure eventually, but for now, it seems to be working. Hail the Subjectivist! Down with the Subjectivist!

That hurt .. then again I am mid-way between objectivist and subjectivist so I remain stationary .. Now I would advise you to not equalize .. rather go by tweaking levels and/or phase and nudges in sub placement ...while taking the FR

 

[cjfrbw]

That hurt .. then again I am mid-way between objectivist and subjectivist so I remain stationary .. Now I would advise you to not equalize .. rather go by tweaking levels and/or phase and nudges in sub placement ...while taking the FR

Sorry, I haven't gotten in the habit of using those little joking emoticons. I tease objectivists a lot because it is so easy to get a rise out of them. However, audio reproduction would not exist without objectivists and their rigorous contributions, so I guess I am somewhere inbetween as well.
I am in Santa Cruz for the weekend, so no more experimentation until Monday. It is surprising that the smallest 10 inch subwoofer above ear level can clean things up like that, it is probably about 20 percent of the total subwoofer moving diaphragm area.
The best overall description I can give is that the third subwoofer very notice-ably increased the "transient stiffness" of the bass, whatever that may mean, it's hard to describe.

 

[Gedlee]

Measurements are ideal, but at LFs they can be difficult to do. I have done a lot of sub setup by ear, it gets close, but nothing can compare to seeing the reuslts because it shows you areas that need work. So do the setup by ear if you have to, but do measurements if you can. One thing that I would agree with below is that if you are doing this all by ear then do not use EQ, just use the sub levels and phase. EQ is so precise that its very unlikely that you can get it right by ear. Sub levels, placement and phase are rather gross changes that the ear can do a decent job with.

 

[Steve Williams]

Measurements are ideal, but at LFs they can be difficult to do. I have done a lot of sub setup by ear, it gets close, but nothing can compare to seeing the reuslts because it shows you areas that need work. So do the setup by ear if you have to, but do measurements if you can. One thing that I would agree with below is that if you are doing this all by ear then do not use EQ, just use the sub levels and phase. EQ is so precise that its very unlikely that you can get it right by ear. Sub levels, placement and phase are rather gross changes that the ear can do a decent job with.

Fascinating thread. Great read . Thanks Earl

so I have a pair of Gotham subs. What sub would you recommend. Frantz, you've been to my house. What sayest you?

 

[FrantzM]

Steve

Sometimes it's wise not to mess with a good thing .. If you must experiment .. Use one of the small JL Audio subs, either the f110 or the f112. For what they will be doing as the third sub in this configuration, I don't think you need anything more potent ...
You will need an additional pair of arms, another pair of ears and patience.. I also would advise to leave everyting else as is.. Simply bring in the 3rd sub aand make the l3evel on the third sub NOT the others .. Leave these alone.. You are simply adding a third subwoofer...You will play with the phase, croosover freq ( I suggest in your case 50 Hz) and phase of the third subs .. I would advise of no change in the current settings...then you'' decide but be warned you may be shocked by the new level of bass purity and the pressurization of the room when it is called for ...

 

[Gedlee]

In principle all the subs should be matched together, along with the mains. This is why the setup of multiple subs can get difficult, because adding each sub, again, in principle, will cause one to change all the others. I have found this to be the case in most of my setups. This is why I wrote a computer program to do this, because by trial and error, it can be very tedious.

 

[FrantzM]

Earl

A case of not sleeping because of a project due for today at 9 AM and fortunately all set and ready ..
Interesting, I remember reading on your web site that you did offer such a service to your speakers owners, something about recording of some tones, sending them to you and returning setting files for the Behringer DCX crossover ...
Is this program available for the public?

 

[Gedlee]

Earl
Is this program available for the public?

NO, sorry, its not.

 

[cjfrbw]

Just to elucidate, my sub positions are close to the Geddes/Frantz recommendations. 1. One full range Velodyne ULD 15ii in the right corner behind the mains 2. James EMB 1500 full range about halfway between the rear wall and my seating position on the right as I am seated. 3. A 10 inch Von Schweikert sub left of my seating position about halfway between the left wall area/ listening position and about a foot and half above my listening position (ears). I am sort of in the middle of the two rear subs in a criss-cross pattern when I am seated.

(By "full range" for sub I mean rated down to below 20 HZ +-3DB.) The 10 inch is also rated to 20 HZ +-2DB.

 

[FrantzM]

Just to elucidate, my sub positions are close to the Geddes/Franz recommendations. 1. One full range Velodyne ULD 15ii in the right corner behind the mains 2. James EMB 1500 full range about halfway between the rear wall and my seating position on the right as I am seated. 3. A 10 inch Von Schweikert sub left of my seating position about halfway between the left wall area/ listening position and about a foot and half above my listening position (ears). I am sort of in the middle of the two rear subs in a criss-cross pattern when I am seated.

Would like to stress that the placement recommendations are all from Dr Geddes. I simply applied them and have become an ardent proponent of the method. For the record. I don't own any Geddes speakers or subwoofer. I am however looking forward to audition his speakers and if they sound half as good as their specs (and owners) would suggest I will acquire them.

 

[cjfrbw]

Would like to stress that the placement recommendations are all from Dr Geddes. I simply applied them and have become an ardent proponent of the method. For the record. I don't own any Geddes speakers or subwoofer. I am however looking forward to audition his speakers and if they sound half as good as their specs (and owners) would suggest I will acquire them.

Well, I am glad for the advice and promotion.

I am listening to my Klipsch chuffer-wheezer now, which has been transferred to the Santa Cruz small system.

I like bass any way it is served, and I am enjoying it here with the chuffer. However, I can tell how "loose" and wavering it is by comprison to the main system, though bass is abundant.

I will probably get a pair of super cheapo subs here for my budget system and implement the Geddes/
"sort of" Frantz system here as well to stiffen things up.

 

[Mark (Basspig) Weiss]

thanks earle, can try that anytime. will do the 'serious' stuff at reno time.

kare, if you insist!!, here is the waterfall of the mains only, just mucking around a bit and trying to learn (more, always)

so no subs, just the mains.

be a few days till I get back to the subs, maybe you'll have some advice to help me going back in

View attachment 637

Judging by the standing wave dip frequency, the length of your room is about 16 feet?

 

[terryj]

hi mark

the room is (roughly) 5m high, by 5m wide and about 9-10 m long. So two of the dimesnions are kinda close to your 16 ft. I always had this huge peak at around 100 hz (have not ever bothered to see if that correlates with 15 ft/5m) so in the end I have the system diagonally (sort of) in the room. I still see that fr all the time and have to eq it out, but it seems to have been ameliorated a little with the current positioning.

Over the next few days I will be taking some new measurements )mainly for the other sub thread) to try and show what I have been saying about timing with the subs. If it is not audible per se (the timing I mean) at least I hope to show that we get 'free' output when we align timewise.

ATM I am on a diffusion building thing, later I wall get around to hefty bass traps.

 

[microstrip]

After reading an participating in this thread I found it interesting enough to order a DCX2496. My subs are built with two existing Fujitsu Eclipse 15" speakers (similar to those used in the Krell Master Reference Subwoofer) and one smaller quality aluminum coned 12" with a large magnet. What would be the best allocation for them in a 4x9x2.4m? Speakers are dipolar, placed at 2m from the back wall and I sit at 3.8m from them.

 

[FrantzM]

microstrip

One in the back corner behind the speakers.. In the corner. In my experience that is the best place to put the most potent sub (I think that is Geddes recommendations as well) ... The second in the side wall halfway between the listening position and the speakers plane the third on the other wall off the floor if possible...I would suggest about half a meter in font ofat ear level if possible closer if possible to the listening position... Do use the Free Behringer program to set the DCX 2496 and keep in mind its lights are VERY bright. Remember to bypass crossover,level and phase in your subs if you are using the Behringer. If your woofers have variable level , crossover and phase controls you can experiment without the Behringer. It is not necessary , it does brings however more precision, flexibility and some ability to set delays so that you have the subwoofers time aligned. I must say that while you can set the delay as to perfectly talign the second and third subwoofer, it won't do much for the "main" sub for that you would need units suchas the TacT or the DeQX, these units working with he whole signal could delay the signal to the main with respect to this sub ..I haven't found this to matter at all, I must say ..
Let us know how this turned out..

 

[microstrip]

Franz
Just received the DCX2496. As you said the Behringer PC software for configuration is very simple - I connected the unit it to a spectrum analyzer and a generator and I already have designed a few filters. However I can not find a way of changing the phase, although the block diagram of the unit shows such control in the manual. Do you remember how we adjust it?

Next weekend I will assemble a system with the three bass boxes and an old Krell 3 channel amplifier.

 

[mojave]

Click on the Short Delay tab and you will see on the right side the phase setting for each channel.

 

[FrantzM]

Click on the Short Delay tab and you will see on the right side the phase setting for each channel.

Thanks Mojave ...

 

[microstrip]

Thanks Mojave and Frantz!