Large Vs Small (LFE + Main, Double Bass, etc…)

I shot a video on this subject, knowing full well it would be controversial. I noticed that while playing around with the LFE + Main settings, you could get bass signal back to the subwoofers when you have speakers set to “Large”.

But setting speakers as “Small” on my AVR and the crossover at 80 hertz yielded the best results. So what gives?

In working with SVS, Ed Mullen helped me understand a few things about Room EQ Wizard, and the results I was getting with the Umik-1.

The first lesson was that a marginally better graph does NOT mean better sound. I could vary the phase of one subwoofer and eliminate a null, but it didn’t sound as good. Trust your ears. I keep the subs at zero phase, adjusting timing using the distance settings instead.

I asked Ed about the problems with the LFE+Main setting for the Denon, also known as Double Bass for Onkyo, and I’m sure a few other terms. My thoughts are that some people will refuse to set their towers to “Small” out of sheer pride, so why not let them get the bass back that is typically lost when the fronts are set to “Large”?

When you set a speaker to “Large” or “Full Range” on your AVR, all of the bass on that channel, including signals down to 20 hertz, goes directly to the speaker, and NO signal gets diverted to the subwoofer.

This is bad for several reasons, primarily because, as Ed pointed out, very few speakers are truly “Full Range”. Even their venerable Ultra Tower cannot deliver at 28 hertz the same dynamic output found in their subwoofers, and the Ultra Tower is a truly outstanding tower speaker, especially given the price.

Ultra Towers with PB-4000’s, set to **SMALL** at 80 hertz crossover.

Setting the speakers to “Small” keeps the subwoofer “fed” properly and keeps the main drivers fed more comfortably above the crossover, reducing stress on the amplifier and the main speakers.

Bass requires GOBS of power, and the subwoofers I discuss have comfortably capable amplification, 300 watts RMS/700 watts peak for the very smallest on the list.

Asking your AVR amplifier to handle that load only makes sense in a few, very expensive setups. AVR’s are typically rated at 2 channels (Denon X6300 = 140 watts with 2 channels driven) which gets divided up among the other channels. So not much power when you look at it. That’s a great AVR, but it’s better to lighten the load.

For those who are still hung up on setting their speakers to “Large”, the “LFE+Main” or “Double Bass” setting duplicates the low frequency signals and sends them to the subwoofer as well, which explains the names.

A setting of “LFE” only (instead of LFE+Main) does not send that signal to the sub, making it difficult to integrate a subwoofer correctly. The bass only comes from the LFE channel of the content, and other speakers set to Small. Really difficult to properly integrate.

Then Ed sent me this EXTREMELY helpful write-up:

“Here is the best way to understand Small/Large , LFE/LFE+Main and the LPF for LFE.

  • Small applies a 12 dB/octave high pass to the speaker at the selected crossover frequency.
  • Small sends a duplicate signal to the subwoofer and applies a 24 dB/octave low pass to the subwoofer at the selected crossover frequency.
  • LFE means the subwoofer gets the LFE channel and redirected bass from any channels set to Small.
  • Large sends that channel a full-range signal.  This is also known as ‘Full Band’.
  • LFE+Main sends a duplicate signal to the subwoofer for any channel set to Large and applies a 24 dB/octave low pass to the subwoofer at the selected ‘crossover’ frequency1.
  • When set to LFE+Main, the subwoofer still gets the LFE channel and redirected bass from any other channels still set to Small.

1 Note if the mains are set to Large and the subwoofer mode is set to LFE, there is no crossover selection available for the mains.  If the mains are set to Large and LFE+Main is selected, then the ‘crossover’ selection becomes available for the mains.  This really isn’t a true ‘crossover’ at all, because the mains are still being sent a full-range signal.  What the ‘crossover’ becomes when LFE+Main is selected is the low pass filter setting for the duplicate signal being sent to the subwoofer.  In this sense, the user can select the amount of ‘overlap’ between the mains and the subwoofer.

This distinction is not well understood by most enthusiasts, nor is it well communicated by the AVR GUI menu.  It suggests or implies a crossover is still being applied to the mains when they are set to Large, when in reality that is not the case.

The LPF for LFE is the low pass filter setting for the LFE channel.  Normally this is set to 120 Hz, since that is typically the upper limit used by DVD mixing engineers.”

-Ed Mullen

So yeah, I think you can begin to see why I like SVS so much, and why I worked to become their first ever affiliate. The knowledge they have on hand is world-class.

So basically, with the “Small” speaker setting, your crossover is a “soft” limit for your mains/towers/center/surrounds, with only 12 dB/octave of filter below the crossover setting. The speakers still get the bass signal, just not as much of it.

A tower rated for 32 hertz is absolutely worthwhile, even when crossed at 80 hertz. Some people might feel their tower’s capability is “wasted” in the small setting, but that’s just not the case.

Even a bookshelf can produce enough bass signal to cause havoc under 50 hertz when set to “Small” and crossed at 80 hertz. I had some bookshelves with passive radiators that had nasty peaks at 40-50 hertz, and I’d blamed it on perfectly functioning subwoofers!

So again, you’re still getting bass signal to your main drivers when set to “Small”.

The crossover setting is more of a “hard” limit for the subwoofer, at 24 dB/octave, which means it really chokes off the subwoofer above the selected frequency. It’s a stronger filter (24 vs 12). That’s why I feel crossover is less about what you’re “keeping” from your towers, and more about what you’re “giving” to your subwoofers.

I appreciate Ed Mullen at SVS taking time out to offer his input on this subject, it has been a confusing one that I understand much better now. I think we both agree that the “Small” setting is best for 99% of applications. I knew what I was hearing, and his contribution above really added a lot to my understanding of the issue.

Hopefully this helps clear it up for you too! Set those speakers to “Small”, even the large ones!

Ryan B.

21 thoughts on “Large Vs Small (LFE + Main, Double Bass, etc…)”

  1. There is still signal under the AVR crossover point going to the towers and it blends nicely. Bookshelves work great too, though towers can be a little nicer. Towers are icing on the cake, not a requirement for great sound. Of course, some bookshelf speakers do better than some towers, so it’s all relative. 4 SVS Satellites plus a center sound great with PB-2000’s. The towers sound better.

  2. What would you suggest to those with def tech towers with powered woofers…small setting or large?

  3. If you are running a basic subwoofer(s), your towers may do better with bass than the sub, in which rare case the Large setting may be better. But if you’re running quality subs like those found on The List that can truly go down to 20 hertz, then I would run them at 80 hertz set to Small. If you are running duals, 80 hertz should be good, but if you are running a single, you may run the crossover at 60 or 40. This is because the subs in the towers act as dual subs, knocking down the standing waves. Of course, listening to the different settings and going with the best sound to you is the way to go.

    Even set to Small and crossed at 80 hertz, there will be output as low as the towers can go, just not as strong. You can verify this by setting the towers to small at 80 hertz, turn off the power on the sub(s) (not the tower subs), and run a sweep like this: Bass Test – 2000 hertz – 1 hertz and you should get output as low as they go. The best settings depend entirely on the subs you are running.

  4. BRAVO,BRAVO!! Now i understand. Setting my crossover at 80 hertz on my towers, center and surrounds also gives me more power for cleaner highs and mid range. I also noticed a heat reduction in my AVR. My cooling fan doesn’t come on as much because the heavy load of bass is coming from my subwoofers. The highs and mids sound much stronger and less strained. Thanks guys!!

  5. Very glad to hear! Running a higher crossover is almost like getting a higher powered amp. I like to run at least 90 hertz on my mains, and 120 on smaller speakers, but every situations is different. Thanks for the feedback!

  6. I have a question. I was running 1 polk audio PSW 505, but then I added another one to my system, is it in my head or are the 2 subwoofers playing deeper bass than just 1 could achieve?

  7. I’m not qualified to diagnose psychosis 🙂 but I do know the bass will be “fuller” with less “gaps”, and that could give you the impression of deeper bass. As for whether you get an effective increase in extension is something I can’t say with certainty. You can use my YouTube playlist to see how deep 1 goes vs 2. As the bass drops, you will notice somewhere under 50 hertz it will start to get quieter and taper off. Subwoofers I prefer don’t tend to taper until about 20 hertz, which is about the human limit, and very rare.

    The point where it starts to taper is what I consider to be it’s “effective limit”, which is usually higher (shallower) than factory rating, with subwoofers I prefer being pretty reliable exceptions. I’m curious if your perceived “taper point” changes with 2, it’s something I haven’t explored.

  8. I have Definitive technology BP9040 powered towers and Martin Logan Dynamo 1000 subwoofer. What settings would you recommend? Currently I have the BP9040s as large using just speaker cable, Sub woofer LFE+Main at 80 Hz

  9. You could try bumping the crossover to 90-120 hertz to see if that does any better, but that’s probably the way to go the way you have it set up. The subs in the tower are active that way, correct? You could also try running a lower crossover, say 40 hertz, and bumping your Dynamo gain a bit to boost the low end. One of the few times I would recommend such a thing, but it has a lot to do with the built in subs in the towers. It won’t be like having a true “Deep” sub like on “The List” but you might be able to get a more powerful lower end that way. Ultimately, your settings are probably good where they are at, but it’s always good to experiment.

    I haven’t played around with powered sub towers, so I’m guessing here, but cutting off the Dynamo’s output above 40 hertz may allow you to run the gain higher and have a more impressive low end. With subs that already have a deeper presentation, I say go the opposite way and increase crossover, but your situation is unique with a sealed sub and powered sub towers. By setting the crossover to 40, increasing the gain on the tower subs and the Dynamo, you “might” get a deeper sound, but using Room EQ Wizard would be really handy to see what’s actually happening.

  10. Thank you for your reply Ryan! I made the following changes and everything sounds really great now. I connected LFE channel on BP9040s separately to AVR, set them to small and crossover 80 hz, and changed Subwoofer to just LFE 120 hz

  11. Great insight. Quick question then: Is there ‘value to leave the crossovers for the speakers at separate values? I.e. after running Audissey on a new Denon for example, THEN switching the fronts (which it identified as ‘large’) to small and 80Hz crossover; my other speakers all have varying crossovers up to 140 (it’s a 9.2 setup), as set by the Denon/Audissey. Should they all be at 80Hz (they are all fairly high-end), or left where they are to crossover earlier?

  12. I wouldn’t lower a crossover from where Audyssey sets it. Audyssey sets it at the lowest point where it is capable of producing output, but in terms of dynamics you can usually add 10-40 hertz to that setting. For example, I run satellites that register 80 hertz on Audyssey at 120 hertz. Sure, they will handle output between 80 and 120 hertz, but the subs just handle it more dynamically. I should also point out that my thoughts on crossovers can be an issue with typical subwoofers that aren’t “flat” in their response. I tried helping someone with a basic subwoofer recently, and I was reminded how difficult it can be with a sub that gets louder at higher frequencies. Subwoofers from “The List” are much more agreeable to my methods.

  13. Great write up, however, I’m a little skeptical about how true what Ed Mullen says is. Have you reached out to any Denon engineer that can confirm his words on the LFE + Main + Large speakers’ crossover setting part specifically.

    What I understand is that enabling LFE+Main and adjusting the Large speaker’s frequency setting that is only available after doing the former, is the amount of “up until how much do you want the Sub and Mains to play the same sounds”

    So if I set it to 60hz, the mains and sub will play all content from 60hz and below at the same time, but anything above 60hz will only be through the mains, NOT the sub.

    It sounds great to me because I have a garbage subwoofer that flutters/farts, so I want my towers to help with it as well.

    I just hope that what I understand and what Ed Mullen states is 100% the truth though, as it is all confusing and very little written material exists on it.

    Thank you so much!

  14. Ed doesn’t get it wrong too often, but feel free to contact him at SVS or contact Denon to see what they can tell you.

    From what he wrote, and what I hear in testing his explanation, I’m confident in his appraisal of how it all works, but I will be pointing Denon to this page to ensure it is correct. Ed is kind of a legend, and they take bass pretty seriously, so I’m not too worried. I agree that there is little info available.

    If that sub flutters and farts, saddling it with only 60 hertz and lower probably won’t help too much, as those problems are more likely to occur under 60 hertz. 60-90 hertz should be relatively easy, if not you might as well switch the thing off if it’s that bad (and some are, for sure). 60-90 is probably it’s most “functional” range, true for most subwoofers. Setting it at 60 hertz probably leaves it with a 10-20 hertz effective range (assuming it does poorly under 40 hertz, cut off at 60 only leaves 40-60 hertz functional bass range instead of 40-90 hertz) but setting it at 80-90 will probably make it sound boomy.

    Long story short, it sounds like a nightmare to adjust, which is probably how you got here.

    When you’re ready to upgrade, matching dual subs from my “List” should resolve your problems, and bring a whole new level of enjoyment to your setup. Where that sub is struggling to keep it together, these subs will positively thrive.


Bass defines your home theater

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