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Bass Management

Ron Texas

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#1
Nearly all active sub woofers come with a control to roll off the sub at frequencies from around 35 hz to 120 hz (it varies). I am wondering about different ways to roll off the mains, or if that is even needed.

1. Consumer AV receivers will roll off the mains and even have a sub out to roll off the sub. I suspect they don't measure well.

2. I am using a Crown XLS 1502. It has a high pass filter which is variable. The disadvantage (if you want to call it that) is it measures a lot worse than a Hypex based amplifier. However, a lot of folks get good results with these. This amplifier has been reviewed here at ASR.

3. ASR member @mitchco wrote an article published at Audiophile Style on how to use Audiolens to fashion a crossover in software. I don't totally understand how to put this together. My take is it is a very high performance approach.

4. MiniDSP makes some combination DAC, crossover, room EQ hardware. Prices start at $205 for the 2x4 HD. It has been reviewed at ASR. It has a 90 db SINAD which isn't all that great. If I wanted to upgrade my Crown to a Hypex, it would be a waste to use it with this DAC. MiniDSP makes a much nicer unit, the SHD with Dirac and Volumino built in. It's only $1200, but they will throw in their calibrated microphone because they are so nice. The SHD has been tested here at ASR.

5. I wonder about the viability of not rolling off the mains at all. I don't believe this is a good alternative with speakers like the LS50 which I have now, or nearly all 2 way bookshelf speakers. However, with tower speakers having significantly better power handling I wonder if this would get good or great results. There aren't any tower speakers I am in love with right now, either.

6. Some of the active speakers have bass management built in. The LS50W even has a sub out connection. For $2200 I consider it a possibility. My LS50's could be sold or given to a relative. If I wanted an upgrade this probably makes more sense than buying an SHD plus a Hypex amp.

Any comments on the viability or preference for any of these solutions? It's not just about what I might do, but what some of the brain trust around here thinks about the general problem of rolling off the mains.
 
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#2
I am kind of in the same boat. I have never had a room with good bass response at the LP from either main speaker position, and after trying various configs my definite favorite is handing off bass duties to multisubs:
1) Yamaha AVR performed crossover duties fine and measured well in room via REW, but just sounded so lackluster for music.
2) Moved on to a solution with home theatre bypass preamp (enabling easy switching of main speakers/subs/amps/bass management between home theatre and music processors). Emotiva XSP-1 preamp (with analog sub crossover), and currently a Topping D10 DAC. Sounds excellent, but I do have a measured delay between mains and subs. I don't *think* I can hear the delay since it sounds good to me, but it appears from my reading on the subject some experts say it is audible while others say it is not. I also like this setup because there is only one DAC and no ADC conversions (unlike using mini-DSP 2x4's etc.).
3) Being OCD, though it sounds good to me, the delay between mains and subs is just stuck in my head. So I am looking to try an all digital solution for crossover/eq. After trying my mini-DSP 2x4 for this, I did not like the sound quality so it is relegated to sub duty (which its perfect for except for low preamp output). Looking at mini-DSP SHD, PC with convolver and multichannel DAC, or such as a solution.

Now if you are lucky enough to have good measured bass response at the LP from both mains, I would definitely think not crossing those over would be beneficial as they now simply become part of a multisub solution (in general, the more sub sources the better for modal smoothing).
 

Ron Texas

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#3
Now if you are lucky enough to have good measured bass response at the LP from both mains, I would definitely think not crossing those over would be beneficial as they now simply become part of a multisub solution (in general, the more sub sources the better for modal smoothing).
This is more or less what I am thinking. 2 way stand mounts benefit a lot from being rolled off because of their limited power handling. There is also a reduction in distortion.
 

DonH56

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#7
Some people like not rolling off the mains but I am not one of them. It makes achieving good bass response harder, makes subwoofer placement and integration more challenging, increases the distortion in the mains due to the large bass signals, and reduces main amplifier headroom for the same reason.

I've always rolled off the mains as whenever I have not all the problems above contribute to poorer sound if I do not. YMMV. I have used active and passive line-level crossovers and now depend upon the crossover in my processor.
 

RayDunzl

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#8
Nearly all active sub woofers come with a control to roll off the sub at frequencies from around 35 hz to 120 hz (it varies). I am wondering about different ways to roll off the mains, or if that is even needed.

1. Consumer AV receivers will roll off the mains and even have a sub out to roll off the sub. I suspect they don't measure well.

2. I am using a Crown XLS 1502. It has a high pass filter which is variable. The disadvantage (if you want to call it that) is it measures a lot worse than a Hypex based amplifier. However, a lot of folks get good results with these. This amplifier has been reviewed here at ASR.

3. ASR member @mitchco wrote an article published at Audiophile Style on how to use Audiolens to fashion a crossover in software. I don't totally understand how to put this together. My take is it is a very high performance approach.

4. MiniDSP makes some combination DAC, crossover, room EQ hardware. Prices start at $205 for the 2x4 HD. It has been reviewed at ASR. It has a 90 db SINAD which isn't all that great. If I wanted to upgrade my Crown to a Hypex, it would be a waste to use it with this DAC. MiniDSP makes a much nicer unit, the SHD with Dirac and Volumino built in. It's only $1200, but they will throw in their calibrated microphone because they are so nice. The SHD has been tested here at ASR.

5. I wonder about the viability of not rolling off the mains at all. I don't believe this is a good alternative with speakers like the LS50 which I have now, or nearly all 2 way bookshelf speakers. However, with tower speakers having significantly better power handling I wonder if this would get good or great results. There aren't any tower speakers I am in love with right now, either.

6. Some of the active speakers have bass management built in. The LS50W even has a sub out connection. For $2200 I consider it a possibility. My LS50's could be sold or given to a relative. If I wanted an upgrade this probably makes more sense than buying an SHD plus a Hypex amp.

Any comments on the viability or preference for any of these solutions? It's not just about what I might do, but what some of the brain trust around here thinks about the general problem of rolling off the mains.

1. No experience with modern AVR. I listen to video in stereo, sound taken optically off the TV.

2. More power is (opinion) better than less power, which you tend to get with the PA type amps, but there seems (opinion) to be something good with better home audio amps (of equivalent power). I've used PA amps in the past. My Krells (however poorly they might actually measure) certainly seem (opinion) to do a better job here than what's come before them.

3. Audiolens and Acourate (and others) are, I suppose, about as far as you can go rearranging digits. @mitchco wrote a book on how to put it together.

4. I have an OpenDRC-DI (digital I/O) and a 2x4HD (analog out) - the former modifies everything, and then (currently) a preamp out goes to the latter for four individual subs. The digital I/O doesn't make problems, and the 2x4 analog doesn't need to be too refined for sub duty (opinion).

I have separates, and likely will remain so. Division of Labor appeals to me more than a shove it all into one box solutions. One of my devices has failed, I'm suspecting a power supply cap, its current usage was just "display", so, the music plays on.

5. I run my mains full range, with reduced SPL in the bass, where the Cheezewoofers overlap. With 3 bass drivers per side (woofer and two subs), each can run 9dB lower than the single mains driver. It sounds a little richer on the low end, but I would like to get better subs (someday). So, the mains are not rolled off, but they are shelved to some degree.

I could roll the mains off using the OpenDRC-DI, and let the Cheezewoofers handle the lows, but I don't hear a problem with what's working now, and, measurably, the mains go lower than the subs. So, haven't messed with it. Being retired, there's no time for anything. Oh crap, it's Tax Day.

6. No opinion, other than I still have separate devices for separate tasks. Choose your poison.
 
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#9
My experience FWIW:
I'm using a Venu360 for bi-amped mains & subwoofer xovers, and have settled on not rolling off the mains, after a lot of listening.
I'm also using a XLS1502 for the sub (JBL 4645C).
Since I'm running JBL 2216ND-1s woofers on my mains, I've found that they go as deep, but with more, uh, precision, than the 4645.
The sub, however, delivers considerably more Slam! when needed.
For now I have the sub crossed over at 65hz.
I too am wondering/considering a subwoofer amp upgrade (Bryston for mains LF) - curious about how much of that 'precision' difference is the Crown XLS.
 

PierreV

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#10
I wouldn't overly worry about SINAD for subwoofers tbh (personal opinion ofc). Am currently playing with a SVS SB2000 and a pair of LS50 in my office right now and the main issue I have, by very far, is the room itself. Playing with volume, phase and crossover gains or loses 2-3dB here and there. Room modes get me 7dB dips and 10dB peaks. Still crawling the sub, but takes time because of the furniture. Will probably settle for the minimal dip and attempt to correct the remaining peak in roon.
 

Willem

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#12
I am using my main speakers (Quad 2805) full range, and a B&W PV1d sub with its internal low pass filter crossed over at 33 Hz. Unlike Ron's pro audio power amp my Quad 606-2 power amp does not have a high pass filter, although it is somewhat bandwidth limited.
I was wondering if there is as imple way to add a little bit of high pass filtering to my Quad 606-2, such as by the Harrison Labs Fmods in between my preamp and my power amp, but after I have split the output to direct some to my sub (I must admit I am already using inline attenuators to reduce the 2 Volt output of the DAC/preamp to the 0.5 Volt Input level of the Q606-2.) A bit of high pass filtering would lighten the burden for both my power amp and for the main speakers. Does anyone have any experience?
 

DonH56

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#13
If I understand correctly you want a line-level crossover? There are many ways including rolling your own. An expensive analog solution is a dbx223 professional crossover. Cheaper is a miniDSP unit, more expensive things like Marchand active or passive crossovers and all the way to Bryston or DEQx crossover units. And everything in between. For simple, analog crossovers I like the little dbx units, e.g. https://www.sweetwater.com/store/detail/223XS--dbx-223xs

I definitely would not power Quad ESLs full-range but YMMV.

HTH - Don
 

Willem

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#15
My B&W PV1d subwoofer has a sophisticated digital filter, with precise selection of frequency, slope, phase etc. But it is only a low pass filter, so if I want to somehow have a high pass filter for the main speakers, it has to be inserted in between the pre amp and the power amp, but after the Y cable from the pre amp and that splits the signal into a cable to the subwoofer and a cable to the power amp.
 

Ron Texas

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#17
Based on the above discussion I see these alternatives, and not in any particular order:

1. Do nothing, it's always a choice.
2. Get speakers which don't need a high pass filter next time around and a Hypex amp. This only makes sense if I want a different sound.
3, LS50W since it would cost less than a MiniDSP SHD plus a Hypex amp. Keep the existing sub.

I don't consider the discussion over by any means. The topic is complex. Small speakers which need a sub the most also benefit the most from a high pass filter.
 
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#18
I have mains that are rated "no need for sub with music for sure" Salk ss8 - I roll mine off at 80 and put the sub in at 80 (LW 24db crossover) via minidsp. (specifically the dirac 22a). I also implement Dirac at this point. I was pretty happy with receivers doing this work, but I wanted to get 2.2 working a 2 channel only preamp is what made me go in this route. Ultimately I take a 2 channel signal, apply crossovers to achieve 2.2 and put Dirac correction on top with a house curve with a touch of bass and naturally follows the 10k space to oblivion instead of trying to boos it. I really like mixed in subs and do not want a 2.0 only system. Any basic receiver can mix in a sub which can at least tell if you if you like it at all.

The advantage to the minidsp crossover vs the Crown is you can pick the type and slope of crossover in minidsp, I dont recall if crown lets you pick the crossover, just the set point. Minidsp has more crossover options.

1. works fine, you can borrow a unit from me if you need a preamp to play with - pm me
2. sounds fine, might be over thinking this a little - minidsp would have move crossover options
3. they all do roughly the same thing, mixing a sub needs to be outside of your computer...ie a minidsp...ie just get Dirac on minidsp
4. works good
5. I think you need to spend a good bit or DIY to get acceptable bass down to 20hz...so alot more than a LS50 honestly
6. full outboard control is more apealing than a paid solution inside another solution, but thats just a personal approach
 
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#19
...mixing a sub needs to be outside of your computer...ie a minidsp...
Forgive me if I misread your post, but just to make sure:
1) mini-dsp *is* a computer, and mixing a sub is done inside of it
2) If using a computer as a music source (i.e. windows, mac, linux), mixing a sub (as well as all other DSP functions such as active crossovers, phase correction, FIR, etc.) can be done inside of it before passing on to analog domain (via convolvers, AudioLense, etc.)
 
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#20
Most users have a 2 channel USB dac or the like for computer audio and don't have the additional hardware to do more than 2 channels, the basic minidsp give then four to work with. We are saying the same thing.
 
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