How do you high pass your main speakers?

I'm guessing your speakers were designed to handle their low frequency limits.

If the amplifier driving those speakers has adequate output to drive them, the methode of the high pass filtering may interfere with their designed presentation.

Its something you might try. High pass filtering is far from a panacea simply because subwoofers are being used.

The region where your speakers are rolling off is like a landing pad to lay your SVS subwoofers crossover onto. I'm assuming your feeding your sub-bass speakers the equalized line level signal from the SVS. 

I use the high level connection on my REL T7i subwoofer (i.e. speaker wire connections to the power amp), so filtering between the pre and power amp is not an option. Is there a way to add a high pass filter for my speakers at the speaker wire output of my power amplifier?

@mapman 

In particular with small speakers, removing the two lowest octaves can greatly reduce the distortion, not just across the bass but well into the midrange, so the speakers sound more transparent with improved soundstage, and eliminating the bass also increases the speaker’s dynamic range a great deal. It’s a really life-changing experience.

Even if a speakers output drops it doesn’t mean the cone displacement does, quite the contrary, an effect which is made worse with ported speakers.

Well said.  I don't know about "life-changing" but your other points are spot on.  IME, the effect/benefit is greater with main speakers that don't go too deep or don't handle high power well.  I use the Marchand XM446 fully balanced high pass filter and because of the low frequency capabilities of my main speakers, I had them roll it off pretty low at 45Hz.  I roll the subs in about 40-45 Hz and the result sounds great.  Neither of their passive filters, the XM46SB-AA (single-ended) at $325 nor the XM446XLR-A (balanced) at $525, break the bank for a well-engineered high pass filter using high quality parts.  For folks seriously looking at this option, I suggest calling Marchand and getting what you need, rather than farting around with capacitors.

In order to fine tune a subwoofer’s crossover you need to be able to select both frequency and slope of both the high pass and low pass filters independently.

Well.... kind of sort of but no... 😀

@mijostyn in an ideal world we could effectively turn a 2 way speaker system into a 3 way and apply the same amount of thought and flexibility to both the high and low pass filters and integrate a sub just like you would a driver in a speaker cabinet. I do actually favor this approach... but it’s not strictly required if the low pas filter section is flexible enough and lets us apply EQ and control the slope and delay. That is, we CAN get a little hack-y. with the method I suggested assuming I have a DSP to manage the subwoofer from and will achieve really good results.

I do agree that no matter what you do a delicate and fine tuned integration of the subwoofer is essential. After high-passing the mains the remaining issues are relatively minor and QED with good measurements and a DSP.

I keep meaning to do a blog post on exactly how this would work, so stay tuned gang! :) I will put my money where my mouth is and take lots of measurements.

@erik_squires , The only way eric that you can do what I have been talking about is with digital signal processing. The reason you have to have independent control over both high and low pass filters both 3 or 6 dB down points and slopes is because after matching time and phase the game is keeping the subwoofers out of the midrange and relieving the main speakers of as much bass as possible, two conflicting issues. Using digital signal processing to "room control" the subwoofers wastes a lot of power and stresses the drivers. It is better to use a cleverly designed room and subwoofer array to keep nodes to a minimum and use dsp sparingly.

I am going to be Beta testing DEQX's new Pre 8 preamplifier shortly. Read up on it. It is quite a unit.

Measuring your system is always a great idea if you really want to see where your problems are. I evaluated a friends system yesterday after installing his new Clearaudio Charisma. He has a small but very nice situation in the lower level of his condo. His system has minimal distortion but he complains of not being able to tolerate louder levels and he lacks refined imaging. His problems were laid bare on the computer. His system was +5 dB at 10 kHz and the left and right channels had very different curves throughout the midrange. The high frequency boost is the reason he can't listen at louder levels and the variation between the channels is killing his image. He also uses two subwoofers with low pass filters only. After seeing his issues on the computer he is ordering a MiniDSP SHD preamplifier with which we can conquer these issues and more. 

@erik_squires , The only way eric that you can do what I have been talking about is with digital signal processing. The reason you have to have independent control over both high and low pass filters both 3 or 6 dB down points and slopes is because after matching time and phase the game is keeping the subwoofers out of the midrange and relieving the main speakers of as much bass as possible, two conflicting issues.

@mijostyn

First, weird that you can actually see how my name is spelled and still chose to misspell it.

Second, you are thinking too much like a speaker builder, which I am and respect, but it’s leaving you locked in your thinking. As speaker builders we think of the electro-acoustical properties of each driver and come up with a happy balance of slope, delay and phase matching, but if we are limited by what we can do in one filter section we can compensate for it in another. For instance, if your tweeter requires a steeper rolloff then you can compensate by removing a pole in the woofer.

This same principle also means that we can achieve very good frequency and phase matching if at least one of your filters (high or low) is one you have complete control over. So a simple high pass filter on the mains + DSP on the sub will work beautifully.

I’m working on a project right now to help demonstrate this more fully, I hope you find it helpful.

In any case, no matter how you chose to integrate a subwoofer, whether we use a DSP for both high and low pass filtering, use no high pass filter, or take the approach I suggest, taking in room measurements is essential. The basic speaker specs are practically useless in determining the appropriate filter settings once in an actual room.

@erik_squires Please excuse me Erik and no it will not or rather it will but not optimally. It is a half baked method of crossing to subwoofers. 

@erik_squires , modern digital preamps like the Anthem STR, Trinnov Amethyst and DEQX do the measurement for you and correct most of the problems along with providing crossover filters. The DEQX will quadra amp a system if you so desire. 

There’s optimally and very very good, @mijostyn . :) I wager I can get to very very good, but rather than dicker in hypothetical arguments I’m going to put my money where my mouth is. I find that more convincing. :)

Yes, absolutely being able to control high and low pass is the easiest way to integrate a satellite and sub, but in many cases a user is specifically choosing a non-DSP based preamp and processor and hence my solution.  BTW, my solution is not unlike what Vandersteen does in some cases.  The Vandersteen solution is sound and mine is based on similar principles.

I’ll post back when I have got my project working. :)

@erik_squires    As someone with hands on experience, and after getting plenty of positive feedback from A’goners who have actually tried it, I believe that most everyone who high passes their main speakers, via a line level crossover of some sort, finds it a wonderful end-result.

A very good point erik.

If most of those folks could hear the comparison between David Hall's Velodyne 2011 Digital Drive Plus high pass vs its basic twenty minute Auto EQ, I'm certain the Auto EQ would be the hands down preferred choice. Since the sale of the company it seems any further updating of the twelve year old software has stalled while prices have more than doubled making it a questionable recommendation. 

@mijostyn     1.The only way eric that you can do what I have been talking about is with digital signal processing. 2. Using digital signal processing to "room control" the subwoofers wastes a lot of power and stresses the drivers. It is better to use a cleverly designed room and subwoofer array to keep nodes to a minimum and use dsp sparingly.

mijostyn +1  I found this to be case with 7.1 home theater (same speaker hight and distance) setup from the listening position. This greatly reduced dependency on processing and a far more enjoyable surround. I was taught how to map the rooms low frequency standing waves in the late 60's by the guy who sold me his Octavium, my first subwoofer. 

I can't speak to the prospect of digitizing the entire audio band as a means to control subwoofer room optimization, that's another topic. Despite my main speakers and the two DSP subwoofer systems providing what seems to be the best of both worlds, I'm still interested in hearing your impressions with DEQX. 

I am in agreement with @erik_squires 

Read this article

http://www.troelsgravesen.dk/High-Pass-Filter.htm

Thanks @perkri !

I paricularly think that audiophiles should focus on this sentence from Troels, which is in alignment with my previous statements:

But not having the midrange driver pumping deep bass has a positive impact on the midrange as well and it also relieves the power amplifier of some back-EMF coming from the speaker drivers. Pretty much a win-win situation.

While Troels is discussing a 3-way system with a dedicated midrange this is essentially the same as taking a 2-way and adding a subwoofer. High passing the satellite has enormous audible benefits that outweigh all of the puritanical nit picking by far.

Re: the OP and his sealed ATC SCM19 main speaker design with its huge magnet, large 3" and underhung voice coil SL-woofer, the distortion numbers here are already quite low up through the midrange, and my previous "leave it as it is"-answer (i.e.: don’t mind high-passing them) was partially in relation to this context. Granted, as a sealed design there’ll be excursion maxima at the tune, and thus there will be some influence into the mids at more elevated SPL’s with low frequency material exciting the cones into prodigious movement, not least if/when the voice coil exceeds the gap and its linear motion, but at more typical listening levels it’s a lesser issue.

Question remains: when will the efforts of high-passing them be worth it, and naturally this depends on the specific implementation of a HP-filter among other things. Given a fully active DSP-configuration steeper HP-slopes can be easily chosen, and it’ll make the HP-function and its sonic implications all the more effective. A mere 1. order slope here will still have some "bleeding" into LF-territory and is really only a half-baked solution - even with an 80Hz HP. Myself I’m implementing a HP over my mains at ~85Hz, 36dB/octave L-R slopes, and that’s with dual 15" woofers per channel w/100dB sensitivity and 800W continuous power handling - that is, tested with material into the bass region, so add a bunch of dB’s of effective headroom when high-passed as described. What’s interesting with such a powerful main speaker system is the difference a HP still provides for here; natively a ported design tuned at a relatively high 40-ish Hz, high-passing them removes the character of the ports, cleans up the mids even further with sharper leading edges, and seamlessly "delivers" them to a pair of very efficient 1/8 space loaded tapped horns that are quite "characterless" as well - not least when compared to the sonic imprinting of a variety of dual 18"-loaded direct radiating subs. All of this makes for a more seamless integration with the horn section from ~600Hz on up (111db sensitive). Indeed, here a HP over the mains makes a world of difference.

@erik_squires 

Your quote from Troels sounds as if he is discussing a 2-way speaker, where the midrange does double duty serving the bass too.  Why would the midrange be “pumping deep bass” on a 3-way speaker?

Not.all stand mounts are 2 or 2.5-way speakers but even with woofers dedicated to bass frequencies, there can be benefits of using a high-pass filter when using subs, such as keeping the LF drivers operating in the range where they are most linear and relieving the power amplifier of some back-EMF coming from the speaker drivers as presented in the quote from Troels that you shared.

@mitch2 I suggest you read the original article.