Best Way to Integrate Subwoofers?

What’s the best way to integrate subwoofers with monitors, or speakers?

I’m not referring to placement, or room treatments. I’m referring to what’s the best way to integrate via a crossover, without a custom dedicated crossover.

Do you run two separate signals to the subs vs the speakers and supress the lower frequencies to the speakers, while supressing the upper frequencies to the subs? It would seem that this method might allow you to move the crossover to higher frequencies, relying more on the subs for the bass and lower mids - if that is beneficial. It would also seem that this method would permit you to taylor the slope of the crossover to minimize overlap of frequencies between the subs and the speakers, which might improve clarity - depending on the capability of the particular crossover used. And, I suppose it implies / requires a separate crossover to be used to run both signals through to route the mids and highs only to the speakers and the bass and lows only to the subs.

Or do you run the same signal to the subs and speakers and just emphasize the subs up to the bottom of the frequency range of the speakers, crossing over from the subs to the speakers at that point (crossover notch). It would seem that this method would require you to fix the crossover at the bottom of the frequency range of the speakers, wherever that may be, and would not require a separate crossover to be inserted into the signal path. And it would seem to imply that the slope of the crossover would be limited to the slope inherent in the subs and speakers, which would limit the flexibility of the crossover.

Or, does it make any difference?
Active crossovers between the pre-amp and amp is the best way imo.

You run interconnects from the pre-amp or dac to the subs, then from the subs to the amp. Only the high pass goes to the speakers. You then can adjust the phase and crossover point. I find steep 24 dB slopes work best for sub crossovers.

JL audio’s Cheaper E112/110 have a decent one built in that works well. The kicker is you lose the room correction with the E-sub line compared to the fathom line.

JL audio make an external one that is very good and works with any brand but it is pricey. i am sure there are other options I just don’t know of them.
Crossover point is very speaker dependent BUT I have pretty much always found it best to cross-over where the mains bass  driver hits minimum motion. Meaning where the bass driver’s output drops off and the port picks up. For many speakers this is 50hz-ish give or take. 

You can run the speaker lower but most of the time the sub is much better than your speakers below 50z (even large good passive speakers). This also frees up the main amp to not work as hard and take vibrations out of your mains. 

Saddly large speakers work better with subs than small speakers. They blend better and the power-band hand off is better too. 
I prefer using a high pass filter to the speakers. Some prefer running the speakers full range. It all depends on the speakers that you are using with the sub!
So... if you use an external crossover (other than the one, which may be built in to the sub) - do you insert it after the subs?  I guess that location would use the sub controls to adjust the curve of the subs, and the external crossover to adjust the curve of the mains?
I’ve been low-passing subs at 40 Hz with 24 dB/octave slope to avoid overlap with the speakers because I didn’t want to insert an active high-pass crossover between my Ayre preamp and amp. I’m going to try a fully balanced passive high-pass crossover at 80 Hz with 24 dB slope between the preamp and amp, adjusting the subs up to 80 Hz.  But low-passing the subs to avoid overlap works well, so if the passive filter denigrates the Ayre sound, I’ll return to just low-passing.
Well first of all you use four subs, and it hardly matters where they go just that they're not all in the same place.

But anyway regardless of how many or where, the question is how to get the balance right. Its pretty simple. So here's what you do.

First reverse phase so the subwoofer(s) are out of phase with the mains. Now adjust the subwoofer crossover and volume level until you get as little sound as possible in the crossover range. You will probably need to go back and forth a few times, adjusting the crossover and then the level, looking for the best result. When you do, then reverse so they are back in phase again.


But I worry that I forgot to mention how important it is that you use four subs. Okay, I see that I did say to use four subs. Whew. What a relief.
I like the Paul Mcgowan Method - Run a high level signal to the sub/s from your speaker amplifier. Just some extra speaker cable from the same banana's that are going to your mains. This has the benefit of keeping the sound signature of your amp and allows your Mains run full range as god intended. The sub only fills in what the mains can't do. The trick is to find out the best freq to cross over on the sub as you can't rely on the spec sheet from your mains for this. You will just have to listen and experiment. Of course you will need to find a sub that can except high level inputs...
So... I assume that means only the frequencies allowed to pass from the subs to the mains via the mains amplifier are presented by the mains... and... that the controls on the subs provide the various adjustments of how much and how those frequencies pass to the mains (at least for the JL subs).

I did take a look at the JL Audio CR-1 crossover reviews and found this discussion of how the reviewer connected it and dialed in the crossover - which is also very informative.

It appears that discussion, moreless follows your suggestion above.

This all makes sense and is very helpful.    

the crossover goes before the all the amps including the ones in the subs. 

So preamp to corossover to speaker/sub amp. Generally you only adjust once slope and volume of the sub.  

So if you have an external crossover you will to disable the subs low pass if possible.

Good crossovers are are very expensive and a nitch item. If you are just playing with subs for the first time I would look for a sub with a built in crossover (very different from a low pass). I use my built in crossovers and I really can not hear any signal degradation with it in the system. I am sure there is some. But the advantages of the subs far out weight the neatives once set up right. 

Most important is the subs volume. Phase is really hard to hear honesty in the sub range but sound pressure will stand right out. I would get a dB meter and measure the sound at the listiening position using a est CD. 

Jl audio has a document on setting uo phase. It works pretty well, it is online somewhere. 

It will I’ll let you tune the bass to the room which has a profound improvement on the sound. I could never have a system without subs again. Otherwise you need a full range speaker ($$$) and a perfect room and who really has a prefect room? 1% of us, less?

The down side of subs for me is all the extra wires everywhere because I have a 6’ set of leads to and from my subs...


Run full range to mains. Run line level to sub EQ, use sub EQ to integrate.

Cons: You don’t get increased output from your main amp. No extra dynamic range. Sometimes a compromise is to plug ported mains.

Highest dynamic range, most altering of main signal:

Use a crossover after your preamp, before your main speakers.

Cons: Adds more processing steps in series with your fancy DAC/pre and amp.
Pick one.

Sub speaker level in/outs do not include a high pass filter.


So - if the subs have their own amplifier, then both the main amp and the sub amp are driving the subs, and you adjust the subs volume down to mate with the volume of the mains, and then the preamp volume control adjusts both volume levels in synch?

And, ideally then, the subs just present the frequencies below the frequencies inherently presented by the mains - except for a bit of overlap at the bottom frequencies of the mains - which I suppose can introduce some lack of clarity, if the subs can not match the speed, etc. of the mains?

And, I suppose, that does not relieve the mains of presenting some of the lower frequencies to improve clarity of the mains?

Just wondering... because... that seems to be the easiest method, but I’ve read that relieving the mains of some of the lower frequencies, and allowing the subs to extend up a bit, may add clarity, soundstage, and other benefits - which I assume can’t be done without a crossover that can adjust both to avoid overlap.

I guess the method you describe allows for only the sub amp to present the signal for lower frequencies, and allows the use of an external crossover to elevate the frequencies of the mains, if desired. 
REL has it down.  Check out the site and information there.  Best connection and common sense makes for a pleasurable experience!  
+1, dave_b.

I believe in less is better and keeping things simple as much possible. I am not a fan of external crossovers to drive subs. IMHO, no other sub can possibly do bass as seamless as REL through its high level input. The sub receives identical signal as your speakers from your amps without ‘taxing’ your amps.
Correct, the speaker wire from the amp over to the powered sub should only be seen as the signal. It's not actually driving the sub. As for latency, etc... Get a sealed servo sub or 2 or 4 😀. Those should keep up nicely. Volume should go up and down automatically with preamp volume control like normal. Just look for a sub that has high level inputs. REL and Rythmik should fit the bill.
If your mains are not being driven to their full potential currently with your amp then that's a whole separate issue I would takle first. I don't buy the statement that you should relieve the amp of low freq signals from the mains.
Step 1. Get an amp that can adequately drive your mains
Step 2. Worry about the other stuff
"So - if the subs have their own amplifier, then both the main amp and the sub amp are driving the subs, and you adjust the subs volume down to mate with the volume of the mains, and then the preamp volume control adjusts both volume levels in synch?"

the sub isn't being driven by the main amp. The impedance is preventing that. The signal is just high enough to be amplified by the subs amp.

The REL method is simple enough to try compared to the other suggestions.

This is a very complicated problem. Forgetting the variability of speakers and subs there is a best way to do this but the market has not responded yet by providing the equipment options required to do this correctly. What is needed is a free standing digital bass management processor that would slot into the equipment chain before the DACs. You would need four DAC channels one for each sub channel and one for each satellite channel. The first company to get this right was TACT Audio which was put out of its misery about a decade ago. With their system you had complete control over frequency and order and you could change settings on the fly. You could even use different high pass and low pass filters. You could cross all the way up to 10th order if you wanted to all distortion free in the digital domain. It was killer. There is only one unit that takes over where TACT left of that I know of and that is the Trinnov Amethyst. Perhaps Lyngdorf does this also but I am not sure. The only down side for some would be having to digitize their analog sources. Every other approach is a compromise. I personally do not like putting powered electronics in subwoofers. I prefer separate amps and crossovers which allows you your choice of poisons. Several rules of thumb that may upset a few of you. Don't cross so low. Any good sub can run fine up to 200Hz as long as it is in stereo. Right now I cross at 125Hz 48 db/oct. It is much harder to match up drivers the lower you go. Most systems do not need to cross lower than 100 Hz as long as you can use 24 db/oct or higher filters.  I do this with electrostatic panels by the way.
Alway use a high pass filter on the satellites. If you can see a driver move you are doppler distorting everything else carried by that driver. Even with  analog filters the improvement in satellite performance will far out weight any detriment due to the filter. In an analog system the crossover should go between the preamp and amplifiers. The improvement you get in overall system performance will far out weight any detriment from any decent crossover. I think the JL Labs crossover is as good an analog crossover as you are going to find. Hopefully there will be stand alone digital cross overs or even DACs with bass management built in. Once you work with this in the digital domain I promise you will never look back. Regardless of the crossover there are a few other requirements for the best bass. A minimum of two subwoofers is necessary for point source satellites. I use linear arrays and in this case the number of subs depends on the length of the front wall. I use 4 subs at 4 foot intervals along a 16 foot wall. This then functions as a horizontal linear array matching the power projection of the satelites. Subs have to be real heavy. Mine weight just shy of 250 lb each. You should not feel any vibration when you put your hand on the enclosure. Vibration is distortion. Getting that kind of performance in an enclosure is no easy feat. Look what Magico resorts to! Build your own subs if you can. You can do a much better job than most companies because you don't have to worry about making a profit or shipping costs. There are any number of great subwoofer drivers out there. The hands down best buys are from Dayton. I also have a soft spot for Morel drivers. There is no better material for making subs than MDF you just have to make it thick enough. The last subs I built for a friend used 2 inch MDF in a balanced force design (driver on opposite sides ala KEF and Magico). I am warming up to build cylindrical balanced force subs using two Morel TiCW 1258Ft drivers in each of four cabinets. I just have to figure out what I'm going to get for my wife in exchange.
1) Running speakers full range creates phase issues below the crossover point, Gedees advocates this but I disagree, you want all “subs” to be the same model. 
2) Digital/Active crossovers are the way to go, especially if somewhat tech-savvy. The MiniDSP SHD is awesome and can also be used as your pre-amp (high enough quality to not degrade even state-of-the-art systems. 
3) Crossover where the speakers roll-off, you take measurements; for instance, if doing 2nd order on the speaker, find the in-room -12dB point, and crossover at 2x whatever frequency that is. However, you don’t want the crossover to be >100Hz, as then you get localization issues.
I’ve thought about this a lot and have tried it both ways. At this point, I run the mains full range and bring in the sub at around 60Hz. Why this choice? Because it occurred to me that the capacitors in my preamp are likely far better than the mediocre ones in my JL Audio e110. So, why waste the higher quality components of the preamp by having lesser quality ones drive the power amp? By running the mains full, I have the best quality I have available driving my power amp. Also, if I didn’t have a sub, the speakers and power amp would still be carrying a full load as they were designed to do in the first place.
Well - you’ve all given me a lot to think about and experiment with.

I do have a couple of REL T9i’s, as well as a Velodyne and a KEF sub.  So, I guess I’ll start with the REL suggestions... and... go from there.  

But, it sounds like I should have started with the AudioKinesis Swarm, or something like that - perhaps.

We shall see.  
I agree with James63. I run my kef blade 2s and  Jl Audio f113v2 x2 integrated with a Jl Audio cr-1 crossover, placed between my preamp and monoblocks. 
All the literature in Jl Audio is by Barry Oder .
Setting up phase using Barry’s technique, (same in the Jl Audio website) and crossover slope at 24db/octave worked best for me. The cr-1 does not add any noise or corrupt the tone of my ayre amplifiers. 
I also have a set up of rel subs set up the way rel recommends using the speakon connectors and they r far from ideal. 
The Jl Audio set up let’s my kefs open up at the midrange and play with so much more ease , while using my parasound jc-1 amps and now my Ayre MXr twenty.
i have talked and worked with many gurus of bass but no one has helped me more than Barry Oder and he is always available by phone to help.

I have a question...................or two......

There are suggestions from those of this post that obviously have much more knowledge about sub integration than I. But there is a question that may be answered to those who are using an active crossover capable of adjusting the crossover points sent to the subs as well as the mains.......
Should the crossover point on the sub(s) be set to the highest setting and just let the active crossover set the actual crossover value? May seem like a stupid question but if the sub(s) have their own adjustable crossover setting why not just take that capability out of the loop since the active crossover is doing the same thing?" Is there a downside to doing this?

There is a lot going on when you configure a 2.1 system.  I have my main system in a small room that serves as my office, so I don't have to pressurize a large space, so I have it set up studio style with the Jamo Coronet IV's on the wall in front of me, with a Klipsch 10" sub (front firing, front ported) sub in the closet on that same wall.  It sounds amazingly good,especially considering I can't get the speakers out into the room for proper imaging placement.  I use a 80z crossover point from my old Denon 3802 receiver and this allows the Jamo's to coast from 80 on up.

I like how the Parasound P6 and HINT 6 allow you to overlap the crossover frequency if necessary.  But I'd stay away from running the mains full range, you can get into time smear and comb filtering.

I am used to tuning a 4-way PA in unfamiliar buildings, so I've got some reps in doing this.  I try and find the best spot for the sub by running pink noise through it in several locations to look for the smoothest response, (the newer DSP controlled subs will make this easier), and after finding the best spot, run pink through the main speakers at 80-90dBa, then unplug the mains and turn up the sub till it meets that specified SPL.

Then listen and tune to taste.
I also use the JL Audio CR1 and am a big fan of it. I run dual f112v2s and crossover right about 50Hz.  Barry Oder also helped me integrate my subs using the CR1.  He is fanatical about it. Unfortunately, I have heard he has recently left JL.
Anyway, James makes good points about the benefits of running deep bass through a crossover, in that it reduces the workload on your main stereo amp, and also decreases the vibrations in your speakers.  The downside, however, is that you are adding another component into the chain and also need another pair of interconnects (additional cost).  Overall I’m happy with it though.
The Cr-1 is such a great unit and it does not add any character of its own in my opinion . It’s transparent.
barry now has his own consulting business and does house calls. I had the great pleasure of having him over for 2 days in my house .
when u call Jl Audio they still talk about what Barry bought to the industry lol, even after he has left. 
With my pair of f-113 v2 and blades2 the crossover I have set at 90hz . 
In my opinion and decade of working with subs I totally agree with James. 

I'm confused.

My Primaluna HP has a sub out RCA tap that I run to a B&W sub. 

Would I be better off using a Subwoofer Crossover?
One of the main reasons I like high level inputs and letting the sub do it's own low frequency filtering is that you keep the signal as pure as possible for the mains. I think this is especially important if you listen to an analog definitely don't want something in your chain doing an ADA conversion if you've gone to all the trouble of investing in a high end turntable/phono preamp. I think if you can't do high level inputs to the subs (speaker wire from your amp) since a lot of subs don't offer this feature, the next best would be using an rca out from the preamp to the sub while still running the mains full range. Set up the sub to only fill in the low end the mains can't do. This will take some time to get right... although a lot of people will go the dsp route to handle splitting the signal, this will definitely be be easier to get right, but can't look past the ADA conversion... that bugs me.
Thanks newtoncr for your post. I could never understand why audiophiles are so against crossovers. Your link to is greatly appreciated. I found it very informative and reaffirming.
If you only run 1 sub 80hz is the magic number for not being able to detect the sub source position. If you have a stereo pair you can run it up to 200 or even 400hz with some designs, will depend on design and quality of the subs. If you were running 4 subs I think you are better off running 2 corner stacks if they all match. 4 unmatched ones in a line would be quite a challenge for a DSP  processor I would think and you would want to be 80hz or less.

I'm running a rel stentor III at 80hz 2nd order LW roll off on a Lyngdorf TDAI3400 via RCA. Really easy to integrate with that amp. I don't have the room layout for a stereo pair it's our lounge and it serves  music and TV in 2.1 well enough for me. I used to run a stadium ii via high level using the rel crossover at about 50hz and got a very decent integration with some time fiddling. 
I'm a little confused with part of your recommendation.....

"Set up the sub to only fill in the low end the mains can't do"
"using an rca out from the preamp to the sub while still running the mains full range"
If someone used an active crossover to remove frequencies below the capability of the mains, would that offset the disadvantage of adding an ADA into the signal path? Wouldn't the mains perform more efficiently?

I guess it depends on the speakers and the rest of the system. I ask that because it appears that you are fairly knowledgeable about audio systems.

True, if you use an external analog xover you won't do ADA, but you are still adding more 'stuff' in the signal path. I like to keep things as simple as possible. But, a lot of people go this route. Vandersteen subs are famous for doing this. My assumption in all this is you have mains you truly enjoy and an amp to back it up. If you do I'm not sure you need to worry about 'taking a load off your mains'. I think if you just fill in where your main can't go then you are truly going to get a seamless experience.
I have a couple of REL T9/i subs using HLE input from my amp powering Apogee Duetta Signatures.  The subs are wonderful and seamless.  As someone else mentioned, REL has it down.

Adding a grounding block to my subs just perfected the sound even further; tightened everything up and allowed me to hear the clear definition between sub frequencies.
MEN220 from McIntosh would give you crossover capability and Lyngdorf room perfect.

Or, MSB Sub Iso in front of the main amp (s)

What is a “grounding block?”

How did you add it?

“Adding a grounding block to my subs just perfected the sound even further; tightened everything up and allowed me to hear the clear definition between sub frequencies.“
The problem with the Mc MEN220 and DBx Drive rack and to my way of thinking a serious flaw is that they do not have digital inputs! So, you start with a digital source which goes to a DAC turned into analog then to one of these units, converted back into digital, processed then converted back into analog. You have two totally unnecessary conversions. Why just not give us a few digital inputs? A volume control would also be sort of nice then you would not need a preamp!  

May I know which grounding block you’re using? Is it dedicated to two subs? I also own a pair of REL’s Serie S CL’s as well.

I am currently using QKORE6 for my front end components / amps and QB8 for AC and Component grounding.
Just thought I would add my 2 cents too this discussion. I added a pair of JL audio e112s with a JL audio C1 to my dynaudio C4s and am very pleased with the results. it took me a long time with a lot of sub / main speaker placements, crossover adjustments and  sub volume changes to get a sound I liked. Barry and his coworker at JL supporting home audio equipment were both very helpful and a lot of fun to talk to. Two things I would recommend when setting up subs, first get Barry’s setup cd and try positioning a sub forward of the mains  and one to the side of your listing position. In my setup I found that putting subs in the logical positions in my listing room , next to and slightly behind mains caused a murmuring sound (I think it was group delay). In talking with Barry at JL he pointed out that putting subs behind mains causes the main speakers to vibrate/rattle from sub output. He also told me how he setup recording studios with subs forward, I tried subs forward and it worked for me. Finally, as lots of people who have tried integrating subs know, it’s a bit of a black art. 
Sorry about being long winded, Have a good one
Rel ,the best and easiest way to go.
2 t7i
"Rel ,the best and easiest way to go.
2 t7i"

Looks mouth watering...but only 8"...ain't that a bit small?

You can get 2 15" or 12" sealed servero Rythmiks for around that same price....

If that 8" REL can really put-out that would be tempting...
So... what are some of the other grounding blocks you all may use, besides the $5,000 Nordost unit???

“Rel ,the best and easiest way to go.
2 t7i”

Yes... I hope the t9i is as well. Just bought a pair and haven’t set them up and integrated them yet. I have read some comments that they think the t7i may have a little better detail resolution and clarity, because the smaller drivers are faster and more responsive. I guess for some of us it’s not about how loud the bass is, but how resolved, tight and textured it is - the resolution and accuracy.

And I think I read the same thing about the Vandersteen subs - smaller drivers with faster, more accurate, more resolved sound.
Actually guys the best and easiest way to go is four subs in a distributed bass array. I know. I’ve tried. You’re kidding yourselves if you think its easy or even possible to get really good bass from any one sub. Cannot be done. No matter where you put it, no matter how you EQ it, best you can do is get pretty good at one spot. So after a lot of time wasted moving, listening, moving, listening, tweaking EQ, moving, listening, measuring you eventually call it good and tell yourself its good. But its not good. Because in order to get it good, even in just that one spot, you created nodes where the bass is way too loud elsewhere in the room. Its inevitable. Its physics. No speaker, no EQ, nothing ever gonna alter the physics of the room and the wave. So that loud node hangs around messing up the bass. Always gonna happen. No way around it.

Only when you accept reality, accept the physics, then you plop FOUR subs down, do a rough level set, and immediately enjoy bass better than you ever heard before. That’s what I heard last night. Haven’t tweaked a thing yet, already better than anything I ever heard anywhere ever.

Oh and btw, two of those REL subs you all are raving about that cannot possibly ever produce really good SOTA bass cost about as much as the FOUR in a Swarm system that will.
If you don't have room for a swarm system (4 boxes and cables might not work for you), a couple of well places subs (I prefer RELs) using the high level input can sound astonishingly good. I don't like digital EQ as it simply adds more junk to the signal, so by simply moving things around until things sound right, making sure phase is correct, and carefully adjusting the sub levels, you can get some great sound going on.
Hope so - I really don’t want to have to sell my RELs and get the SWARM system.  Though I know Dukes speakers are some of the best sounding available.  His Jazz Modules were legendary.
@bassdude, rather than selling your RELs and getting the SWARM, you can keep the RELs and add two more subs to your room. They don't necessarily have to be the same subs, or even RELs, but of course you still want good ones.
Right. Exactly. No need to sell. Just add more.

That's the thing when it comes to low frequencies, its not so much the quality as the number of the speakers. No one sub no matter how good can ever overcome the physical reality of the long wave nodes that form in every residential size room. For four on the other hand, one on each wall, its easy. 

Obviously four really powerful high quality subs is better than four little cheapies. But from what I've seen four of just about anything will beat one or two of just about anything. So just add more.
So you think my 2 T9i’s (10”), a Velodyne 12”, and a KEF 10” (I think) would work fine?   Both the Velodyne and KEF are high quality subs with little use and in like new condition.  The Velodyne has a room correction circuit and 4 phase settings - a very good sub.
Subs that have a continuously-variable phase control makes integrating all the subs much easier (Rythmiks do), but as long as you can move the subs around physically it's doable. Another way to do it is to have a pre-pro with sub management capability.