Full range speakers + sub -crossover or no?

[Boomzilla]

There seem to be two highly ARDENT schools of thought about using full range speakers with a subwoofer. The first school says ALWAYS use a high-pass filter for the stereo satellites, and the other says ALWAYS run the stereo satellites full-range and then use the sub's plate amplifier crossover to bring in the sub below the natural roll-off of the speakers.

My experience on this has yielded a few factoids:

1. Full range (or bookshelf) speakers with a "bass bump" in their frequency response are the very devil to integrate without a high-pass filter. My particular experience was with Tekton Pendragons, Mine had a big peak (in my room) from about 35 to 45 Hz. I fought them until I was blue in the face, but never ever got them blended with the sub(s) until I threw in a (steep) high-pass filter of 80 or 90 Hz.

2. Speakers without any bass bump, and with smoothly declining bass response are easiest to run full range and then bring in the sub(s) underneath.

3. In theory, using a high-pass filter with the main speakers reduces intermodulation distortion, but to most people, it seems inaudible with or without the filter.

4. In theory, the power amplifier has to work less when the upstream high-pass filter offloads all the bass to the subwoofer's plate amp. But at lower volumes, it doesn't seem to matter.

So what's the Lounge consensus - Full range or filtered for the "main" speakers when used with a sub?

Boomzilla

PS - This is NOT a troll thread - I really want to know. And I'm open to new ideas or suggestions as to better ways to work with stereo speakers and subs. This is not a surround sound question.

[hemster]

As in most cases, the answer is: It depends!

Even with the Pendragons, not everyone will get that "bass bump" - it'll depend on their room topology, contents, etc.

Your theory on #3 and #4 is plausibly correct but given powerful enough amps, it won't matter.

Of course, you've tried using a high-pass filter and without, so what is your preference? That should be the answer to your question.

Personally, I do use a high-pass filter although my amp is more than adequate to cope with the extra load for the bass and my speakers are pretty decent to handle said bass. Also, my sub has adequate grunt (2700W amp!). I had in the past run my main speakers full-range and the sound was not noticeably different.

I rather suspect that most people may not notice any difference with or without a high-pass filter... unless their amp is not powerful enough.

[DYohn]

Aug 15, 2018 16:30:54 GMT -5 hemster said:

As in most cases, the answer is: It depends!

Even with the Pendragons, not everyone will get that "bass bump" - it'll depend on their room topology, contents, etc.

Your theory on #3 and #4 is plausibly correct but given powerful enough amps, it won't matter.

Of course, you've tried using a high-pass filter and without, so what is your preference? That should be the answer to your question.

Personally, I do use a high-pass filter although my amp is more than adequate to cope with the extra load for the bass and my speakers are pretty decent to handle said bass. Also, my sub has adequate grunt (2700W amp!). I had in the past run my main speakers full-range and the sound was not noticeably different.

I rather suspect that most people may not notice any difference with or without a high-pass filter... unless their amp is not powerful enough.

Exactly.

[novisnick]

I run a set of Paradigm Studio 100 V5 and a single PSA S3001i (I don’t use both). My system has the towers at full range, they do not lack bass. I bring my sub up to just below my towers. Blend them and all is good.
I’ve tried high pass with these towers but they didn’t respond well at all. Put the Studios in a different room with different room treatments and its a brand new ball game! Back to quare one.

KEF LS50’s repond exactly the same but in a different much larger room and it lacks much treatment at all. Just wall to wall carpets and a huge sectional sofa.

[DYohn]

So, like Hemster said, "it depends."

[Gary Cook]

I run mine full range as it maintains the fully balanced circuitry through the XSP-1. Inserting a high pass filter removes that. This works with my front speakers as they have a gentle roll off, plus the room is good acoustically, so it’s relatively easy to integrate the sub.

This is not an accident, I confirmed the speaker response with the company owner/designer/engineer before I bought them. There is more to choosing a speaker that watts and frequency range.

Cheers
Gary

[DYohn]

And by the way in my high-end system I do not use a Xover, I spent about a week (no exaggeration) getting the sub dialed in precisely so it reinforces the first octave or so bel0w where the Devore's roll off. So again, it depends.

[Loop 7]

Since putting a REL into my system (2 channel), my speakers (Focal) are running at full range. I just followed the REL user manual and haven't looked back because I've never had a sub disappear like this.

[Boomzilla]

My current speakers (Thiel CS1.6 models) are currently being used with the bass-management of my Arcam AVR550. Sounds good - works fine. But needing that bass management is very limiting.

There are but a handful of stereo preamplifiers that offer bass management, mostly clustered in the bottom half of the performance continuum. The "best" stereo preamp that I know of that also offers bass management is a Parasound HALO model, and I'm not positive about it.

The Emotiva replacement for the Stealth DC1 is supposed to have a built in high pass filter at 80 Hz., but it may not be out for another two years (or more), (or ever), and who knows where it will fall on the performance scale.

So by giving up on bass management, I open up a world of otherwise unsuitable separates, integrated amps, and dac/preamps. And so long as I have speakers without a bass bump, I can get by without bass management. But if something comes by in the way of speakers that I REALLY liked (aside from their bass bump), then those speakers will be off the table (without bass management) because I won't be able to integrate the sub.

Also, the deeper into the bass that a "full-range" set of speakers goes, the more difficult they are to blend with my sub without bass management.

One would think that I could use my jRiver DSP controls to do my own bass management, but that isn't so. I can't take a digital tap of the signal upstream of the jRiver server because then I'd have no way of matching the changing volume of the music with the level of the sub. I also can't cut the bass in the jRiver DSP studio because then I'd be reducing bass to both the speakers AND the sub. The ONLY way to DIY bass-manage the speakers and the sub is to split an analog signal (after the volume control) and then deal with implementing an analog high-pass filter for the speakers. The only solutions I know of for this (car-stereo quality inline filters) destroy the sound quality that I've paid so much to cultivate.

The Crown crossover is the only minimally acceptable affordable filter that I know of - and I can hear it simplify and diminish the harmonic structure of the music. I've read of the JL Audio crossover, but it's prohibitively expensive.

So am I destined to live in AVR land, or are there options I've not thought of?

[pedrocols]

Every speaker I had placed in the right side of the room cannot reproduce 50hz and 60hz very efficiently. I use dual subs to compensate so it does not matter if I use a hi pass filter because the room is doing its thing.

[tslack]

Aug 15, 2018 19:00:17 GMT -5 Boomzilla said:

The Crown crossover is the only minimally acceptable affordable filter that I know of - and I can hear it simplify and diminish the harmonic structure of the music. I've read of the JL Audio crossover, but it's prohibitively expensive.

So am I destined to live in AVR land, or are there options I've not thought of?

Build some - not that hard...

[Boomzilla]

Aug 16, 2018 0:23:17 GMT -5 tslack said:

Build some - not that hard...

Although it's true that a DIY crossover is possible, getting one that doesn't sound like like a car-stereo leftover is less simple that one might think. Also, as the order of the crossover increases (thus steepening the slope of the roll-off) one rapidly runs into problems of ringing and complexity that can also degrade the sound quality. So in short, a DIY filter is perfectly feasible but a good-sounding DIY filter rapidly becomes a totally different proposition...

[tslack]

But you gave me the same advice in 2015...

Equalization: past / present / future

So you see, the answer was inside you all along.
(OP PS violation, but just too perfect...and a little creepy )

[Boomzilla]

Hi tslack -

Things change over time. I know more now than I knew in 2015, and my room is much better damped than it was then. I'm also running different speakers & electronics. And although hemster and DYohn are both correct in their "it depends" answer, I'm more interested in the "depends on WHAT?" end of the question. The most significant variable I've found to date is the the flatness of the bass response in the associated speakers - but there may be other variables that are equally significant.

[klinemj]

I'm in the "it depends" camp. My Maggiess roll off nicely on their own so feathering the sub in to handle what they can't works fine w/o a high pass on hte mains.

Mark

[cgolf]

Interesting topic. So without hijacking the thread, 80 seems to be the default setting for both mains (towers) and filter. I've tried different settings with mine but it never seems to make any difference. Haven't formally spec'd it with any meters. Thoughts?

[pedrocols]

Aug 16, 2018 5:39:59 GMT -5 cgolf said:

Interesting topic. So without hijacking the thread, 80 seems to be the default setting for both mains (towers) and filter. I've tried different settings with mine but it never seems to make any difference. Haven't formally spec'd it with any meters. Thoughts?

I think 80hz is only a default for movie soundtracks.

[KeithL]

In terms of SOUND, it is going to depend on the speakers, your other equipment, and the room.

However, there is ANOTHER reason (which may also be compelling to you or not).

Let's assume that, with a particular pair of speakers, in a particular spot in your particular room, the speakers produce nothing usable below 60 Hz.

Now, let's assume that you send a full range signal to them.

And, let's assume that there are, at least sometimes, sounds below 60 Hz there that are simply not being heard.

The issue is that, even though you're not hearing those low bass notes, all of your equipment is still working to reproduce them.

Your preamp is passing them, your amplifier is amplifying them, the cones on your speakers are moving back and forth in time to them, and the voice coils in your speakers are being warmed by them.

Now, to be honest, the work being done by your preamp is negligible, so we can ignore that.

However, your amplifier and your speakers are working harder in a vain attempt to reproduce those frequencies.

Does this actually matter?

That depends.

It is using amplifier power - which does reduce the amount of headroom you have left to reproduce other sounds cleanly.

And most speakers produce more distortion when running at higher power levels... so they might not reproduce other things as cleanly because they're busy waving around NOT making any of that 30 Hz low note.

Depending on your speakers and your amplifier, these losses may be important - or totally insignificant.

And, depending on your speakers and your amplifier, adding a high-pass filter may adversely affect the sound quality in other ways - or it may not.

The usual guideline is that, if your speakers, and your amplifiers, seem to be "working hard to try and reproduce the frequencies they can't", then you should seriously consider adding a filter.

It may also depend on both the situation and your needs.

For example, our little Airmotiv 4 powered monitors didn't go terribly low.

But, because they were designed as a system, sending a 30 hz bass note to them wouldn't hurt anything - you just wouldn't hear much of that low bass note.

And, if you were using them as a desktop system, in a small room, there would be no reason to bother with a filter.

HOWEVER, if you were to add a filter, you would be able to play them more loudly before they would distort (because they wouldn't be wasting power and dynamic range trying to reproduce 30 Hz notes they can't do).

It's also worth noting that some speakers are much more affected by low frequencies than others.

For example, sealed speakers tend to roll off at lower frequencies, but not experience excessive motion.

However, speakers in tuned cabinets, whether bass reflex or passive radiators, often produce EXCESSIVE motion below their tuned frequency.

(Which generally makes them candidates for a high-pass filter.)

I should also point out that talking about "how good the filter is" is a huge oversimplification.

In some situations, with some systems, even a relatively simple and low cost filter will sound very good.

And, in others, it may be impossible to avoid negative side effects, even with a very well-designed filter made using very nice parts.

You should not assume that a fancier filter will sound better.... or that a low cost one will sound worse... it really depends on lots of things.

In many cases, if you're in serious doubt, it makes sense to TRY a simple low-cost filter.

Then, if it seems to be helping, you can consider whether it makes sense to try more complex and expensive alternatives.

(And, if it seems to make no difference at all, then you have a hint that it's probably not worth the bother.)

Just FYI... here are a few links to some currently available low cost filters....

This one is a fixed-frequency line level high-pass: 

www.parts-express.com/harrison-labs-fmod-inline-crossover-pair-70-hz-low-pass-rca--266-252

And this is a full subwoofer crossover (it comes in low-pass, high-pass, and full versions):

www.hlabs.com/products/crossovers/index_files/Page384.htm

[geeqner]

I tried it both ways with my ELAC UniFi UB5 Speakers (3-Way Bookshelf Types)
These are SUPPOSED to be full-range and with the XPA-2, I have PLENTY of Power to drive them.

However, like my Polk 5JRs that they replaced - they were a little lacking in Low-End "thump".

My Goldenear ForceField Sub has BOTH:

• Speaker-Level Inputs and Outputs (with the Outputs being filtered to those frequencies ABOVE the selected Sub roll-off)
• Line-Level Inputs (can be summed from both L&R or single-ended)

The Speaker-Level Inputs have controls that allow both the Roll-Off frequency and the amount of Amplification to be selected.
The Integrated Amp is purpose-built to drive the internal driver / planar radiator at Sub and Low frequencies.

I found that when I used the filtered speaker pass-thru - my main speakers sounded a bit "tinny" / weak for my tastes. The Crossover in the Sub WAS off-loading the "heavy-lifting" allowing the mains to work within a narrower, more efficient envelope for them, but leaving me with what I considered to be unsatisfactory audible experiences emanating from my new Bookshelves.

However, I found that simply parallel-wiring the Speaker-Level Sub Inputs and Main Speakers sounded more to my liking.

I believe that I got the sub pretty well "dialed-in" to where it IS handling the frequencies that are really beyond the physics of my smallish main speakers (and although the full spectrum is still being "pumped" to ALL speakers - maybe because my new Amp handles it CLEANLY, they do not get "upset" by that low-frequency content). At some point, I may STILL think about obtaining one of the larger REL subs - from what I've seen, even though they seem to rate a little lower in the Wattage / Band-For-the-buck Department than the GE; they do a better job of "disappearing" while laying the low-end "foundation" for the music without drawing attention to themself than does my GE ForceField

If I had a set of more "boomy" Main Speakers - then maybe things would've worked better the other way around.  But if you are careful, I do not see any harm in trying things BOTH ways and letting your ears do the evaluation.

Eventually, when I scrape-up the funds for that XSP-1 that I have been lusting after - I can simply run the mains from the Power Amp and the Unbalanced but adjustable Sub Output to the Line-In on the sub and see how THAT compares.

[Boomzilla]

Aug 16, 2018 5:39:59 GMT -5 cgolf said:

Interesting topic. So without hijacking the thread, 80 seems to be the default setting for both mains (towers) and filter. I've tried different settings with mine but it never seems to make any difference. Haven't formally spec'd it with any meters. Thoughts?

My rule of thumb has been upstream (electronic) crossover frequency should be 2x the -3dB bass roll-off of the speakers themselves. Why? Because if the speakers roll off at 40 Hz, for example at a rate of 12 dB per octave (typical of ported boxes), and you put the electronic crossover (which, for purposes of this example, we'll assume ALSO roll off at 12 dB per octave) upstream, and also set to 40 Hz. - Then the acoustic and electronic roll-offs are additive. And your actual bass roll off rate (starting at 40 Hz.) is 24 dB per octave.

Why is this important? Because you now have asymmetrical slopes on the two sides of the crossover point. 40 Hz. on up rolls of at 12 dB per octave, but 40 Hz on down rolls off at 24 dB per octave. This usually creates a "hole in the middle) at the crossover point.

However, if I start the same satellites to roll off starting at 80 Hz., then the crossover region is now symmetrical (with no dip) and not until we get to 40 Hz. does the additional acoustic roll-off of the speakers kick in. Being an octave away from the crossover point, the acoustic roll off is far less audible (being already 12 dB down in amplitude from the crossover point.

And as an additional factoid - Acoustic suspension speakers typically roll off at 6 dB / octave. What is an octave? A doubling of frequency. For example 100 Hz. is an octave higher than 50 Hz.

Forgive me for belaboring basics, but they're practical when considering filters.