Cornwall IV and subwoofers

Anyone using Cornwall IV with subs?  If so, what brand and size? One or two? Ported or sealed? How are you connecting them? If line-in, what's your low-pass crossover point?  My goal is getting the best integration for music, not HT.

I recently sold my Cornwalls but I was using them with a pair of HSU ULS-15 II subs. Connection was high level tapping off the amp. I’m pretty sure they were crossed at 40 Hz. Two channel music only, no HT.

That speaker big pile chip board and plastic. Buy Maggie or Rockport speaker and and give your ear real treat.
Svs 3000 series tons of great reviews and by owners 
and all adjustments including volume all done with their great tablet,or phone app,
and sealed is always preferred for audio ,much more accurate .5 year warranty free shipping ,45 day audition ,not many 
can compete with that.
@tubebuffer I could not agree more about the rockports. I went from Magico S1mkII to Atria II and could not be happier. They do cost $21K more so a different league all together. 
I’m using a pair of S/510 from REL. I auditioned the CW4 and S/510 together with my amp before picking them up. Definitely improves the soundstage and overall experience.

Connection is speaker level.
I am amazed that you need a sub with the Cornwalls. I have Tannoy Arden Legacy, also with 15" drivers definitely no sub required.
I had Cornwall III plus sub Wilson Benesch Torus connected low level.
In my experience the sub adds first octave but makes Cornwall's deep range less fast.
Hard to calibrate, too.
So I decided to keep CW alone, placing them just by the wall, as suggested by Klipsch.
@wrm57 The Cornwalls are fantastic speakers and I enjoyed them immensely. The LS II just takes everything up a notch, and it's hard to beat a fully horn loaded speaker.

@alan60 I could live with the CW IV without a sub. The bass is very good. The sub just rounded things out a bit on some music. But they can certainly be enjoyed without one.


I run CWIVs with two REL T9i subs.  I would think T7i (smaller units) would suffice.  They are run off speaker level outputs from the amplifier.  They are not necessary, but fill in the lowest octave and provide a good sense of stage depth and make things seem even more lifelike.  
I have Cornscalas, pretty much same specs as CWIV.  I have 100 Hz crossover and feel the subs are "part of the music."  I have two 10" subs.  
@jbhiller Yes, rightly said. I tried the CW4s by themselves and they sound great. I tried them with the REL subs and everything was just better. "More lifelike" is apt. 
I demoed the Cornwall IVs a few weeks ago and the bass floored me and my wife, when turned up. I can’t imagine adding subs to these. 
Interesting about the different comments around the bass. I think it is what you are used too. I run subs (not with cornwalls) and every system without subs seems lacking to me. I need flat sound down to 20hz to be happy with a system. Now that I have had it long-term I can’t live without it. 
I thought the cornwalls lacked deep bass (bass under 35hz?) with them both right next to the front wall and pulled out 5’ or so. Subs would be a must for me. Not to add bass but to extend it. I listen to modern music for what it is worth. 
I have played with subs a lot over the years. 3 different rooms and 4 sets of speakers with the same subs. 

I have found two methods work for any speaker.

#1 use a high-pass filter and crossover where the bass driver of the mains drops down -6db before the port pics up, if ported. This has by far been the best sound for me regardless of speaker I used. It was right around 60hz every-time (55-65). This method lowers the distortion of the mains, let’s them play louder, and greatly reduces port noise. 

#2 using just a low pass and come in where the speakers drop off -6db in your room (including the port). Just do a quick measurement sweep and it will probably be around 35hz (my guess basses on measuring a number of room/systems). This works fine but you will need the phase right too. This method just adds bass but does nothing for the mains to make them “better”. 

The 6db point is important If you use method number 2. If do it at 0 db or the -3db point you will get a hump in the bass where the two phases come together. Using method #1 you can crossover where ever you want. But too high and the subs sound like…well subs to me. The -6db point of the bass driver is a real nice place to start. 
Is there a budget for the two subs. On the low end I would suggest the REL T7-9i or X. Starting with the I series they went front firing and passive down. If you have a higher budget I would go JL Audio F series. Like two F110. If you want a whole mother level add the JL Audio CR1 crossover. This you can use with any speakers or subs. You have to be running separates to use the crossover. Plus it has a bypass for home theater. The last option would be the KEF KF92 sub. This is a dual side firing sub that goes down to 11hz. For $2k it’s a good value. Plus they have a wireless kit so placement is easy. If you are in the Chicagoland area this store lets you demo stuff in your home on your system.
It doesn’t matter how far down your front speakers go. My speakers go down to 25 hz at -3db. Everyone should have two subs. 
Lot’s of good info here. Thanks to all. My budget will flex for whatever gives best sound and integration, and will also fit in my restricted lateral space. Unfortunately, a pair of anything is not really possible, given space constraints, so I’m thinking about just a single sub at this point. If I set it to around 40hz, I doubt it will be directional. I listen almost exclusively to jazz via vinyl and don’t really need to plumb the deepest depths.

I’ve been experimenting with a 15-year old Von Schweikert VRS/1 that I’ve had parked in another system. It’s sealed, 10-in, down-firing, and won’t cross over below 50hz, so it is certainly suboptimal for the Cornwalls, though it is just right for the Merlin TSM that it’s normally used with. Still, I can readily hear the advantages of a sub with the CWs: soundstage opens up, ambience increases, music is more visceral and floats on its foundation. I’m connecting at this point via low pass, and 50hz doesn’t quite mesh to my ears, giving a bit of a hump. Volume is set just to intimate the bottom frequencies, not push them at me.

After reading around, I think I’m leaning toward a Rythmik F12 or F15. They are compact enough, especially the 12, and offer myriad adjustments. Servos get a bad rap among some audiophiles but this version of the tech gets a lot of positive comments for "speed" and musicality.

Has anyone compared Rythmik to some of the other big players like Rel, JL, Hsu, SVS? Curious how it stacks up.


I don't think I'd high pass the CW as was mentioned above. Their bass quality down into the mid  to upper 30s is too good to mess with. I'd just roll the sub in and let it do it's thing way down low.
@wrm57 ,  FYI,  classic golden age jazz (50s-60s) is my favorite cup of tea.  And, the RELs really augment the lifelike sound that's present.  Surprisingly, even with 1950s recordings--they bolster the ambiance of the recording room.  I was playing Oscar Petersen's 1959 Porgy and Bess last night and the RELs do more than I would even expect on such old recordings. 
One more thing---

I think the Cornwall IV bass response is accurate where it exists. It's not bloated at all.  But, if you have a bigger room they may need help to pressurize it.  If you put these in a smallish room, I bet the bass end of things would sound larger than life.  My room is 15.' wide by 22' long with 10 foot ceilings.  It's big for me. 
I am. I have the Cornwalls on low (6") amp stands to get them slightly off the floor in my 13 x 22 listening room. I'm running a Pass 250.8 amp, PS audio DSD JR and Pass XP10 pre amp. I have a REL s510/SHO sub on high level inputs off the Pass amp and a pair of SVS PS3000 subs (sealed box, not ported) running off the pre amp outs on the XP10. I like them because of the mobile app interface and the ability to tune them via the app. I run them all so they come in around 60 hz or so and at a low volume. They all integrate really well. Te Cornwalls are great but lack the very deep bottom end. I also use Roon and Quboz and like Roon really mostly for it's parametric EQ functions. The Cornwall do have a tendency to have a bass boost in the 125k hz area or so, which I trim out with a deep notch filter adjustment on the Roon EQ. overall I'm pretty happy with the Cornwall - they're huge however- even bigger in person that what the measurements suggest! 
For me, and again for me... I have Heresy IV's with an SVS PB2000 pro. It's everything I need. The Heresy's with my Mac 240 are a sweet combination. The SVS gives every recording an easy weight and presence. I really like the SVS mobile app and pre-sets, really lets me dial everything in. Just my two bits..
I have the Cornwall 4’s in a 14x30 room with an SVS SB3000 sub. The sub fills in the bottom octave nicely. I never thought a sub was necessary until I actually tried it. Big improvement. 
Piggy-backing on what @jbhiller said very well, I use the Cornwall IVs with a pair of REL t7i's, speaker level from a Pass INT-60. The RELs have 8" active, 10" down-firing passive. They're small enough that the OP might be able to accommodate a pair. I've tried to cross them around 30-35, although REL doesn't make it easy to be precise in that regard. As jb said, they're not really necessary, but I like to think they add just a touch to the Cornwalls' palpable sense of presence.
I have a pair of Klipsch corner horns, just the bass section.  The go to about 40 Hz and at 106 dB/1w are effective for most listening.  I would not add a sub, but built one anyway. 

I call the Klipsch "subs" because that seems to be the vernacular. 

I do have a sub-sub, which is a 14' transmission line with 4 15s.  Three of those.  TLs are narrow band but efficient.  I can't measure the SPL but it should be flat to 4 Hz and judging from vertical floor movement, about 5.2 Richter.  Good for rocket launches, end of world movies and such.  Maybe some music. 

SVS Micro 3000

good job. Easy to adjust. Solid 500W playing two directions. No more MUDDY bass because you can use the BEST gauge:YOUR ears, which differ from mine! Lol

Hi Bill, Excellent idea. Since the Cornwall's woofer goes up into the midrange using a sub will noticeably decrease distortion. Good subwoofer systems do both HiFi and theater well. The ideal subwoofer system for Cornwalls would require two 12 or preferably 15" sealed subwoofers and a dedicated two way crossover set to 80 to 100 Hz with a slope no less than 28 dB/oct. I would use a digital crossover with room control and delay capability. So, there is no need for fancy electronics in the sub. The best way to do this would be to go to Parts Express and get this,

You will need two of them. They are super easy to build and the driver is better than what you get in most commercial subwoofers. The money you save can be spent on the crossover. I would also upgrade the plate amp to this,