Bass management--high/low pass filtering

Hi OP,

Unfortunately I don't see an easy way for you to accomplish this.  Your integrated has preamp outs, so you can connect your sub's line level (RCA) inputs this way but there's no way to limit the amount of bass that reaches your speakers.  However, you can plug the ports, which I often recommend for 2-way speakers with subs.  This will somewhat reduce the excursion below the tuning frequency but reduce the output so you can turn the sub up higher.  this will make it easier to integrate the two.

If possible however an approach that did let you put a high pass filter in line with your main amplifier would improve upon that.   Maybe talk to MW and see if they have a suggestion? 

yes, my system has a DSP tool as the DAC/Pre/Streamer that also has subwoofer outs and a bass management system so integrating a subwoofer is less tasking with it. So, unless you're willing to change your system I guess others can chime in @cooper52 

That's pretty much what I figured after failing to find anything online. I'll just deal with things as they are and integrate the new sub (yet to be decided upon) accordingly. My previous sub, a REL S/2, worked seamlessly once I got the settings to my satisfaction. Don't really have any interest in doing a wholesale system change just for this. And anyway, I really like the Modwright and would be hard-pressed to find anything within my budget that I think I'd like half so well. 

@cooper52 

Your speakers have decent bass down to about 44Hz -3db.  You can add a subwoofer and set the low pass filter for 44Hz and no need to high pass the main speakers.  

You paid for decent bass from your speakers, why not use it? 

Many subs have active high pass crossovers.  Lots of people use this configuration.

My setup has a separate preamp/amps....I split the preamp output signal and sent part of the signal to an active low pass crossover set at 63hz that then feeds the line level inputs of an integrated amp.  The speaker outputs of the integrated amp feed the 8" woofer of my main speakers, plus it feeds the high level inputs of my active subwoofer, and I set the low pass of the sub at 50hz with reverse phase. 

The other side of the preamp output feeds my monoblock tube amps....there is a 10nF silver mica capacitor that acts as a high pass inline filter that restricts low bass < 63hz to the tube amps, and passes everything else to the 5-1/4 midbass and tweeter that use a passive crossover.

I ran the above configuration without the inline high pass crossover (10nF cap) to the tube amps for a while, and I thought it made a notable improvement once installing it, but every situation is different so it may or may not be a good solution for  you.  I know it sounds complicated from a glance, but it’s not bad, and this setup evolved over time... it made sense in my case and has worked out extremely well for me.

You can start out inexpensive with Harrison Labs in line filters. If it works for you can decide on more expensive solutions like Marchand or JL Audio. I high pass me mains at 50 Hz before the amp. It really helps the sub integration.

There are a couple of options for you. The JL Audio Crossover is an excellent choice.  Another option is the SPL Crossover which I use. Both units allow you to adjust the low and high crossover points on the fly. This does require a separate power amp for the subs, but most subs today have their own built in power amps. The benefit is reducing the demand on the primary speakers allowing them to focus on rest of the music.

+1 @avanti1960 !

I agree with running your speakers full range.  I have the option of setting both the low and high pass filters in my main system.  I find I like the sound better running the speakers full range and now full range out to my subs using the preouts.  I even switched off the low pass filter on my subs.  You need to have a room that is well setup acoustically and I dial in the volume on the bass but it works for me.  I’m a bass guy which is a good thing because only my dog can hear the high end anymore.  Suggest experimenting with your settings and find what you like best.  It’s a fun part of this hobby for this old guy.  

While some choose to use a high pass filter to the main speakers with sub(s), I think there are many reasons to not.  A lot of popularity with high pass filters comes from AVR surround sound, where there are Dolby settings in the AVR processor for this.  the theory is that it cleans up signal going to small main and certainly small surround speakers.

But for great stereo imaging, and disappearing subs, getting the most bass cues possible to your left and right speakers helps immensely. Your ear can localize tones quite low, so using the low pass filter on the sub prevents you from localizing these sounds. Think plucking of the bass string vs the deepest tone it creates.

As @avanti1960 said, you have respectable bass output with your speakers, use it.  This allows the lowest possible cut off for your sub. 
 

Additionally, adding  any filter, processor etc in line with your speakers potentially inserts distortion.  I work very hard to avoid this.  No room correction, Roon processing, graphic equalizer etc. 

I am not knocking quality high pass filters.  But at best they add complexity.  I have enough wires!

the only reason I would consider not sending full signal to my mains is if the woofers were flopping or distorting.  And most quality speakers with good amplification do not do this.

KISS

I'm one to try and keep things simple.  There have been lots of thoughtful comments and I agree that it's usually best to play the speakers full range and then have the sub reach up to that point and fill in.  

Outboard DSP or anything else added to the signal chain will raise the noise floor and is always a tradeoff.  

Start in the shallow end of the pool.  Get your sub and do you best to integrate it.  Unless your room is particularly problematic you should have some great sound.  Only if the sound is unsatisfactory move to the deep end of the pool and add something else in the signal chain.  Good luck and cheers. 

@avanti1960   +1

Adding complexity and restricting the speakers won't help anything. They are design to be full range.

@cooper52 I actually did it myself. I built two high pass filters, one for each channel as I’m running my Audio Research Ref 5SE to two separate ARC Ref 250SE mono blocks. The monoblocks feed a pair of Revel Performa F328Be speakers.

I got some help designing the second order high pass filters from GR Research (they were happy to help me without charging me a dime, which was very appreciated) and I will be happy to share the circuit diagram with you. What made it a little bit more complicated for me was that I’m using balanced connections between the line stage and the monoblocks, but it’s only a few more components.

This does indeed relieve the main speakers from, in my case, anything below 80 Hz, and of course my two subwoofers have low pass filters and with REW I can make sure everything melds really well.

Comments here saying that "main speakers should always be run full range," in my humble opinion, don’t know what they’re talking about. I believe there’s absolutely no basis for that statement, as then in its extension you would say that you don’t believe in crossover filters, as high passing the upper part of the frequency range to the main speakers and let the subwoofers take care of the lowest frequency duty is exactly the same thing as what a crossover filter does inside the main speakers.

@gdaddy1 per my comment above, in my opinion your comment is simply not true

@bimmerlover   Your speakers have triple 8" drivers for excellent bass resonse.

 24Hz (-10dB); 26Hz (-6dB); 35Hz (-3dB)

By crossing at 80hz. you cut them off at the knees. Why buy a speaker this capable and then put a choke on them? I'd bet the triple 8" drivers produce BETTER, tighter mid-bass in the 35 to 80hz range than your subwoofer.

It's called a "subwoofer" for a reason. To lift the line in the sub region. For you the sub would come in around 40hz. It's NOT a woofer. You have triple 8's for woofers but instead your asking the subwoofer to handle this mid-bass range and hobbling the very capable triple 8" drivers. Why buy them if you don't use them?

@gdaddy1 if you know anything about logarithmic scales, at -10 dB it has dropped to a meaningless sound level, so has essentially -6 dB.

The F328Be:s taper out at 35 Hz at -3 dB, which is still a meaningful sound pressure. One of my subs, the KEF KC92, goes down to 11 Hz at -3 dB, a huge difference, and I low-pass filter it at 100 Hz.

In addition, the tube power amps are not that great in controlling the lowest bass as they have a relatively low damping factor. I trust the sub's 2x 500-watt solid-state amps to do a better job controlling the bass drivers.

Besides, I picked 80 Hz, but anyone can choose their preferred high-pass frequency. It is, after all (still, but unfortunately in peril) a free country.

@cooper52 I have an suggested experiment that you could try. Your integrated has both pre-outs and HT-bypass. So, you could send the signal from the integrated’s pre-outs to an active crossover, then at the crossover, fork the signal, sending the higher frequencies back to the integrated’s power amp (via HT-bypass) and the lower frequencies to your subwoofer. 

Options for your crossover include Sublime Acoustic’s K231, maybe a MiniDSP, or a JL sub crossover. 

My experience. I’ve heard a JL crossover + subs in a buddy’s system. I think it sounded great. I haven’t heard the Sublime unit--I’ve only seen OCD Mikey recommend it on his channel as a solid contender for the money. 

I’ve done what your describing with my TV system. In my TV system, I currently use KEF LS50 Wireless II’s, which have their own internal DSP engine with both high and low pass filters. I paired them with a REL HT sub. I had initially tried the crossover at the speaker’s -3db point (45hz) and at 70-80hz (often recommended in HT situations). I left the crossover at 80hz to live with for a while. Then, one day, I found someone’s charts showing when the LS50 speakers distorted across the frequency spectrum and at different volumes. I don’t recall the exact chart figures, but each chart showed distortion across the frequency spectrum when playing the speaker at different volumes like 80db, 85, 90, 95, 100, 105. What I saw in these charts was that starting at some volume, say 90db, that all frequencies 100hz and below were above some distortion percentage while frequencies above 100hz were not distorting. Charts at higher volumes saw a greater distortion asymmetry across the frequency spectrum. From that information I hypothesized that I should try handing off all frequencies below 100hz to the sub to see if I noticed any change in the sound. I went into the KEF software and changed the crossover to 100hz, and even though I wasn’t listening at 90db, the system sounded more effortless. (I also tried setting the Xover to 120hz, and that sounded equally effortless to me.)

Still today, I have this hypothesis that (1) some systems can benefit when offloading frequencies to subs typically handled by the speakers, that (2) crossing the subs over higher than usual (higher than 80hz) can be effective, and that (3) that a good setting for the crossover is the point where your specific speakers begin to distort asymmetrically across the frequency spectrum. 

If you get into JL’s sub integration philosophy, you’ll learn that they’re big proponents of offloading low frequencies from the mains, and of crossing over at higher frequencies, even for expensive speakers that are "made to play full range." But, I haven’t seen JL articulate where to set a crossover at. Anyway, audio is an experiment, and in experimenting with this philosophy, you may find a solution that works for you. 

Marchand Electronics makes a variety of high pass filters and crossovers designed to limit the low frequencies going to the mains. While my mains are very capable down to 40hz, my room acoustics favor the low frequencies near the floor rather than 30 inches above, where overall things sound best. It's not a matter of philosophy, it's listening and creating the right system for your room and tastes. 

As for using a sub for below 40hz, you'll find very little musical information there. Few instruments produce frequencies that low. Its great to have it available but its not something you're going to hear often.

But by using a sub for below 80 or so, you have a speaker specifically designed for those low frequencies rather than a woofer that is expected to produce those as well as much higher frequencies. 

@bimmerlover 

if you know anything about logarithmic scales, at -10 dB it has dropped to a meaningless sound level, so has essentially -6 dB.

The F328Be:s taper out at 35 Hz at -3 dB, which is still a meaningful sound pressure. 

Exactly my point. You want the subwoofer to pick up that lower range. Those speakers do 35hz and up really good but you're not going to let them do their job. So, why did you buy them? Because they look impressive but you're only going to use half the drivers capability? Makes no sense to buy something and not use it because the tube amp is mis-matched to the capability of the speakers.

FYI... bass in music lives in the 35 to 80hz range where your speakers are optimum but your amp is weak.  

It's your system and you are free to set it any way you want. However, it's not good advice for everyone and could hinder more than help.

@gdaddy1 if you don’t like my approach, which I have explained in quite the length, why don’t you quietly move along. I was merely responding to the OP as I believe I have some relevant experience relative to his question. 

First of all deep bass is totally non directional. I've seen audiophiles stand right next to a sub crossed at 65 Hz and tell the demonstrator the sub wasn't working. The demonstrator had to take the grill off the sub and have the listener put his hand on the sub and it was roaring away. All 'sub' directionality comes from harmonics.

Secondly adding a high pass takes a huge load off the woofers of the main speakers and if done properly the frequencies above the high pass become more open and defined and dynamic. I know. I had stand mount SEAS Froy 3 speakers to which I added big woofers crossed with 4th order Linkwitz/Reily high and low pass filters at 85 Hz and it only took seconds to hear the improvement in the sound. The but is a simple generic high pass may not work. It may take a specialized high pass to work with your mains. The advantage of rolling in a sub where the mains roll off is the high pass is no longer a problem. But you're only getting half the advantages of adding subs.

@avanti1960  another +1 for the same rational as @gdaddy1 +1.

I was unable to enter the ELAC RS500 Manual. I found their Auto Room Correction claims uh, interesting.  

Forget me. I think you'll finally get to hear and feel the deep end of audio. Free shipping, product support and easy return policy. Bravo Elac!

Certainly seems like no brainer.  

All the best

M

JL audio's CR-1 active crossover will do the trick. About $3500 new I think, tons of flexibility for crossover points for high and lows, dead silent and transparent, excellent reviews. Feed your pre amp out into it and then your "trimmed" high level output back to your amp input; run the "bass" output to your dedicated subwoofer.

A minidsp SHD (not the best quality perhaps, but your mileage may vary) can be used as a streamer with bass management, if you intend to keep the modwright in the chain. They also have other models in their product list.

For a more polished/ turnkey 1 box solution, the Yamaha R-N2000A amp (w/ integrated bass management features) will do it really well. I got to measure this unit.

Accuphase used to make some very high quality units

etc

Guys like @phusis may have suggestions on other items that can be used to achieve the above.

@cooper52 --

I use subs in my setup that "meet up" with high-passed main speakers, but they’re all outboard actively configured via the same DSP/digital crossover, mains + subs, and thus high-passing the mains isn’t an extra measure per se. Rather it’s treating the mains + subs as a single 4-way speaker system per channel as an outset with a DSP unit that handles crossover duties for the entire speaker system (save for the "super tweeters" that are passively configured), and so the high-pass filter over the woofer/mids in the mains is just a natural measure on top of the other crossover points to have it all mesh nicely together with the separately housed subs. 

While I’d typically recommend high-passing the mains in conjunction with the use of subs, in your case with passively configured main speakers - and depending on how much you’re willing to invest, one way or the other - I might go with simply adding on a pair of active subs (not just one) and experiment with their built-in low-pass setting to best gel with the mains. Don’t be afraid to have the subs overlap a bit with the mains (this can be beneficial), and also try and find the best slope and not least phase setting. With regard to subs placement, as an outset I’d set them up flanking the mains symmetrically, one sub close to each main speaker. Or sidewall placement, again symmetrically. To me symmetry to the mains placement of subs is more important than diagonally or otherwise asymmetrically trying to optimize smoothness of frequency response, even when low-passing the subs below 80Hz, but to each their own. If you would do so anyway, try out a DBA with at least 3 subs. Experiment and see what you like best, and maybe you already do know. 

I haven’t used miniDSP iterations myself, but know people who do and have heard their active setups. From what I’ve been able to assess though the miniDSP doesn’t cut it for me, and so my recommendation would be for very high quality pro DSP units like ACX (previously named Xilica), XTA, LabGruppen or - even more expensive - DEQX. All of these are great, transparent digital crossovers, and somewhat more costly than the miniDSP’s.

But again, that’s just me in the context of a fully active setup where I need an excellent DSP to handle crossover duties over the entire frequency spectrum of mains + subs. Nonetheless, in your case I’d either go all-in with a quality DSP unit to high-pass your mains and optionally low-pass passive (i.e.: sans both internal amps and XO’s) subs with outboard amps of your own choosing, OR forget about high-passing your mains, run them full-range and add on a pair of active subs with their built-in low-pass filter.  

Once again, this has been quite the education. Thanks to all for your suggestions and input on the subject. In the end, this seems like too many hoops to jump through to get the high-pass filtering to work in my system, and my previous experience with a sub (my late, lamented REL S/2) tells me that, as interesting as it would be to try, it's just not going to be practical. In particular, I'm not willing to invest $3K plus in JL Audio's CR-1 just to see what would happen. 

My room and my setup preclude using a pair of subs. I can only fit one in that space, and the REL sub filled things in admirably. For our listening tastes, at the volumes we are comfortable with, one sub is more than adequate. 

Still, I've learned quite a bit from all your responses, so again, thanks!

Every room, and every system is different. My take is don't buy new stuff until you need it. Also what is the problem you are trying to solve for? Like are you missing bass, or are you missing deep bass?

Run the mains full spread, add the sub, adjust it to fit your mains. Then live with it for a few weeks, it will take several adjustments to get right. From there, figure out if you want to cross over your main speakers or not. 

My HT has everything crossed over, my mains are at 60hz, subs are also at 60hz, it works well there. Plenty of bass, clean sound.

The 2ch has the mains running full, sub crossed at 40hz. Tried all the hi-pass and low-pass settings. It was just missing something. Lost body and tone on my mains. Sounded almost hollow in spots. After weeks of messing with it, went no crossover on the mains, and 40hz on the sub, the light just clicked, this is correct. 

My other half felt the same way. Was listing, she walked in, looked at me, and said "this sounds great". That was all I need to hear about my settings.

@cooper52 the crossovers I made, with some help from GR Research regarding the schematics, caps and resistor values, cost me about $250 in total, using high quality components and about two hours of my time. It’s also quite a fun DIY project, and far from a $3,500 trial investment. Let me know if you are interested in more details.

One of the best discussions on topic I've read here.  When I posed this question to Verity Audio they agreed with most of you to leave main speaker alone and adjust your sub. Thanks all.

This very issue -- how to apportion audio frequencies above the desired cut-off point to the mains, and leave the rest to the subs -- defined my "sub journey" for years until I finally put some time & $$ into a solution:

It’s an electronic crossover. Mine is a single-ended, variable crossover point model from Marchand, a designer well known for high quality crossovers. I bought this one used for ~$500, and it has worked flawlessly for years. I run the output of the preamp to the input of the crossover, which splits the frequencies into 2 output pairs:

• High pass: Frequencies above the crossover point I chose, 75 Hz, go via RCA IC to the class D monoblocks (bel canto 600Ms) that drive Harbeth 30.1s in a nearfield/desktop configuration (strange but true)
• Low pass: Frequencies below 75 Hz go vis a 2nd RCA IC to the JL Audio e110 sub, in which I have the internal crossover bypassed

This crossover has trim pots for each channel to adjust the output of the crossover in +/- 1 dB steps. Once that’s set, all volume control is done by the preamp.

The Marchand uses 24 dB/octave crossover slopes, which work quite well in my desktop setup with a variety of speakers. This component is very transparent: I’ve compared the sound with direct wiring through the amps to the speakers (no sub) vs wiring through the crossover (also no sub). I can’t hear a diffrerence.

Before using an electronic crossover, everything I did was stumble, fumble, audiibly inadequate. This crossover instantly made the problem go away.

Dear Sir;

I use a subwoofer with a hi pass filter on 12 pairs of speakers.  I own 1 way, 2 way, and 3 way speakers.  1 way and 2 way the high pass filter is set at 80hz. with 6 or 12db slope.  On small 1 or 2 ways I use 12db high pass slope for 5 inch and under drivers.  3 ways are set at 60 to 80hz with 6 db slope.  The low pass filter is permanently set at 24 db per octave and the crossover frequency is 70hz.

In my experience, 1 or 2 way speakers benefit the most. Sending the bottom two octaves, 20-40 and 40 to 80hz. to the sub makes things much easier for the little driver.  You should hear my Markaudio Alpair 10p's play Blue Man Group.  The reproduction quality is startling!

Hope this helps

Macguy  

Is it worth it to send the signal through another box of electronic junk just to eliminate frequencies below 80Hz? I'm not sure myself, so I am asking in earnest, not sarcastically. My main drivers (8") are running full range with no crossover at all (Ref 3A NEFES II)

I'm not sure about my above question, and was hoping for some responses. Personally I think it's about a 50/50, but others more knowledgeable may have a better informed opinion.

@koestner Is it worth it to send the signal through another box of electronic junk just to eliminate frequencies below 80Hz?

Depends on how the high pass filter is achieved, and also depends on the system and user, so the solution will vary accordingly.  

I’m bi-amping with tubes on the midbass/tweeter and a solid state amp to the woofers below 63hz,  and yes, I was concerned about junk in the signal path from my sub’s high pass filter.  

 My solution for eliminating the bottom octave(s) from the midbass was to use a quality silver mica cap to the amp’s input as a high pass filter (similar what GR research suggests. ...you need to know your amps impedance to calculate it.).

I'm ok with using a cheap active crossover for the low pass to the solid state amp below 63hz because it's in a much less critical frequency range than the high pass would have been.  This worked great for my situation, but may not for others.

I do have a Marchand XM66 that splits a 24db/oct. high and low at any selected frequency, but I'm only using it for the low pass while the mains get full range signal.