Multiple Sub Woofers - Page 2

Thanks Dennis. Appreciate the info.

4 subs really?Why not 8 subs?

From what I've read 4 is supposed to be the optimal amount. I have 4 SVS Ultras calibrated with a ASEQ1 and the results are outstanding.

8 subs will give you more output, but 4 locations is the point of diminishing returns when it comes to the benefits we've been discussing. So, while you will get slightly greater seat-to-seat consistency and bit smoother response, it won't be commensurate with doubling the number of subs. Big expense for small benefit. Get 4 better subs instead.

The correct number (optimal) is 5000; however, four were found to provide effectively the same results.

Dennis,

I am thinking about buying your services for my upcoming dedicated room. I take it you do offer providing designs for European customers?! I read that you have experience with both my types of speakers: Danley SH-50 as fronts and Genelec 1037C as surrounds.

About multiple subwoofers:

- when you design systems do you combine the same kind of subwoofers by principle? Therefor multiple subwoofers of the same model or at least the same "kind" - sealed, ported, horn, band pass or passive radiator.
Do you consider it problematic combining different kind of subwoofers in one system - like what I consider right now: 2 sealed with 2 subwoofers with passive radiators?

- When using EQ do you apply it on the combined output of all subwoofers or do you EQ each individually? My current approach is to optimize each location and find the best combination of delay settings to get a good basic response. Then I EQ the combined output.

- Do you always run all subwoofers from a single DAC output? Or is running a set of subwoofers only for LFE duties, with another set only for the low passed speaker signal a viable option?


Thank you very much!

We have done several European rooms, yes and we do have experience with both Danley and Genelec.

Typically we'll have a different sub in the front than on the sides a back walls. For example, putting a DTS10 or Procella P18 in the front of the room is relatively easy. In the back and along the sides of the room we are typically more space constrained and will utilize passive subs such as the Procella P10si (or an in-wall Genelec).

We will take the sub output from the decoder and run that into (usually) a QSC DSP 322 or DSP 922. Within the QSC we split the single sub input into three (or more) individual outputs. We can then calibrate all of them together and individually as required for the room, the space, and the individual characteristics of each subwoofer. Where we can change the low pass frequency for the LFE channel, we will. We prefer to have the LCR's crossed over (and usually that is at 80Hz).

Thank you, sir!

So in general it depends...;-) And you react in a very flexible way to the circumstances.

I take it you have no reservations to combine different kind of subwoofers (like horn and sealed designs) in one setup.

Did you do any designs having dedicated subwoofers only for the LFE channel, with another group of subwoofers handling ONLY the low-passed speaker signals (with your mentioned XO at ~80Hz)? Do you see any advantage in that concept compared to mixing LFE and lowpass into one signal for all subwoofers?

Thanks again.

I haven't come across a case where there was any advantage to doing as you suggest. OTOH, I've many, many cases where such a plan would muck up the works.

Now when you say 4 subs, what about size and of course quality. I have read great thing about inexspensive Hsu up to $20K Wilson Thor's Hammer. Would it be better to get 2 reference subs, or 4 mid-fi subs?

....but, first, we need to talk about the space ... it's size, dedicated or not ...etc.

I've got a similar system to yours and I partially agree.


McIntosh MX150 2-MC601's, 1-MC205, PS3, and 2 x F113 subs, B&W 800 Series Diamond speakers.

I thought the MX150 Room perfect did an amazing job with the single F113 x-over at 50hz, the sub was better integrated and much less noticeable at "most" frequencies but sometimes I could discern where the sub was in the room. Also, I didn't like how the seats closest to the sub had more bass then the seats furthest away.

I said to my dealer I'd try a second for demo and let it be known that the second F113 sub brought a whole new dimension... I let the MX150 run the subs in stereo and each sub is located beside the mains. At "every" seat the sub bass is uniform and added depth to the music is welcome. Best part of all, I can no longer localize any of the subs. This is with MX150 Room Perfect engaged.

You should give it a try!

Plenty of variables, including the room (see Dennis' post). For example: if the "mid-fi" subs don't go below, say, 30Hz then four of them won't give you ultra low frequency response. But if the reference subs are like many high end items, where you're paying a lot more for a relatively small difference in performance (diminishing returns), then four lower priced subs can yield better results.
To use those examples: a pair of (passive) Wilson Hammers will set you back $42k; for 1/10th the cost you can get four (powered) Hsu ULS subs. The latter will go as low and loud, but can give you better overall results due to taking advantage of four room locations instead of being limited to two.

Let me start off by saying I am not the expert. But when I went from one sub to two the difference was phenomenal. Like the comment above I noticed uniform bass and added depth to the entire room. I would never go back to one sub. But maybe the biggest expert of all is Dr. Floyd Toole who is a huge advocate of having multiple subs... He is the one that all others refer too....

Food for thought for you " more than 2 is better", but not 4:

http://mehlau.net/audio/multisub_geddes/

I really have no room for a second sub. The McIntosh MX150 and my treated room will have to do.

McIntosh MX150 2-MC601's, 1-MC303, MCD500, MVP881BR, Parasound Z v.3 zone amp, Parasound Z v.2 zone tuner, Panasonic DMP-BDT350 3d blue ray player, Wadia 171i transport, Mac Mini, JL113 Subwoofer, Direct tv dvr, Mitsubishi 82837 & 3DC-1000 3d starter pack, Martin Logan CLX aniversary addition, Stage center, Motif surrounds, Universal MX-3000 remote, Richard Gray/Furman line conditioner

The Welti paper linked earlier, which mentions diminishing returns when using more than 4 subs, has to do with improving seat to seat consistency. There is no mention in that paper about improving low frequency response.

By comparison, the Geddes method primarily tries to improve the frequency response around the main listening area, where his experience shows diminishing returns when using more than 3 subs. But Geddes isn't firm on that: i.e., if a 4th sub audibly improves the bass, then by all means use it.

So the "optimal" number of subs (where diminshing returns start) depends on what you're trying to do. For example, if your goal is to emphasize the stereo bass effect (low frequency envelopment), then going beyond 2 subs would lessen the effect.

^ Thank-you Sanjay, well put. I sometimes forget I am a dedicated 2 channel HT guy. I can't afford to duplicate my 2 channel system's quality in another multi channel system. And I don't miss hearing ambiance sounds behind me. So, yes I can see for a multi channel system, 4 subs it is.

I use four subwoofers in my system.
Two came with the JBL synthesis 3 system and are both passive, with 10 or 12" cones
I have two more passive subs - each sub has three 8" cone drives.
I power them with the JBL S400 amp (not very high current, therefore not for high sub 60 hz SPLs).
I use only one of the passive subs for the LFE channel (which i actually set at relatively low spl - I am not a fan of sub freq SPL - hurts my ears!).

I am not a fan of the high excursion/high spl room rattling self powered sub woofers. I have heard only a few of them - all under $1500 price range. They did not seem accurate and were simply too "boomy" for my personal taste. Of course, my personal preference might well be a small minority. Most seem to want room rattling "effects".

My processor is Lexicon MC 12 and it has L, R and C sub out with individual cross over.
I use the three passive subs to augment the main speakers. My main speakers are actually large 12" cone + Horn electrovoice speakers. Obviously, their cone is large enough for the low bass but I find that using subwoofers to augment the front three channels produces a more "full range" effect for me. I am sorry but I don't recall the cross over settings on the MC12 but I am guessing that I used 80 Hz. The idea being, that the main speakers become more accurate, with sub 80 Hz removed and the small passive subs offer better efficiency, up to 80 Hz. But I don't like the idea of sending LCR sub 80 Hz to a single sub.

My personal preference is less interest in the sub 40 Hz frequencies. My set up is unsuitable for those who want the very low sub woofer frequencies.. Some one wrote 10 Hz.. Wow.. that's quite low.

This forum has experts and I certainly am not one of those.. This happens to be my set up; just a note for your thoughts..

In the context of this discussion, the number of subs is not related to the number of speakers in the set-up. 4 subs is "it" (point of diminshing returns) only when it comes to improving seat-to-seat consistency.

If your 2-speaker set-up is in front of a couch, where all three seats are important to you, then the above applies to you. But if you have a single listening chair or only care about the sweet spot on your couch, then you don't need 4 subs; one or two will do fine with some EQing.

Good bass is good bass, and you should use as many subs as needed to achieve your specific goal, irrespective of whether your set-up is mono, stereo or surround. It has more to do with the number of seats than number of speakers.

You have a beautiful room, and very nice gear. But I don't think imo that you have enough treatments in that room. Expensive gear can only sound as good as the room permits. Actually you can make expensive gear sound bad in bad room. Considering how big your HT is, and how you have multiple seats, adding a second sub should make a noticeable difference.

Well, in that case, you just saved me a lot of money, as it is just me and my sweet little lonesome spot.

Hey guys. I currently own 2 Seaton Submersives and have them next to each other as there's simply no where else to put them as there too big. Now I'm running an Anthem D2v processor and have provided my ARC results (bass needs a little work) in that thread and was wondering if implementing a smaller sub like an SVS PB12NSD would assist in the overall bass response? I could place it at the back of the room behind the main listening area but to the left so it would be opposite to where the submersives are currently placed (front right of the room).SVS sub link here:

http://www.svsound.com/subwoofers/ported-box/pb12-nsd

Is this worth considering as I know it's not in the same league as the submersive but I can't fit (nor afford) another submersive nor do I have the room as mentioned.

Putting them next to each other is like only having 1 sub instead of 2. You can always sell 1 of them and buy a second smaller one so you can place elsewhere. Having the same subs is not as important as correct placement. Your two subs are acting as 1 and you can get better results using 2 subs properly positioned even if they are not in the same league as your submersives as you mentioned.

I've done my research prior to getting my second F113, so 2 subs is definitely better than 1 (based on my experience), and 4 subs is the utmost best, but what about 3 subs??

Is it worth going to 3 subs and is it tangibly better than 2? Or should one not bother and keep the 2 subs and later just go straight for 4 subs ? Rarely to I hear about a 3 sub config.

For 3 subs I would put one beside each main speaker and one in the middle of the back of the room.

What do you think?

Are you referring to my post?

http://mehlau.net/audio/multisub_geddes/

Good thread .

If you want to see analytical justification & explanation of all of this, here is an article I wrote recently on it: http://www.madronadigital.com/Librar...imization.html

It also covers more advanced techniques for subwoofer optimization.

Good to hear. A couple of subs should do you fine: move the first sub around until you get the best response possible in your room, then move the second sub around until the peaks and dips get smoother. Use any controls (level knob, phase knob, etc) on the back of your subs to improve the frequency response. For your situation, the Geddes method you linked to is an excellent primer.

BTW, since you can't do the same thing with your speakers, you'll have to rely on bass traps to address low frequency problems above the subwoofer range.

^ Thanks Amir. It is always informative and a pleasure to read your posts.