To Sub Or Not To Sub, That Is The Question

[LL21]

I spent many hours with Barry Ober and I feel my system is the best it's ever sounded. I'm not touching a thing! It is a science and a little luck thrown in to get speakers and the room to sound good with subs.
I have 2 JL 112v2 subs with CR-1 crossover. My mains are rolled of pretty high with a very gentle slope. Subs and mains are all aligned with woofers/subs on same plane. I've always felt subs are not to augment the bass of the mains, but to fix room issues.

Hi Bruce,

Interesting...Where do you crossover your main speakers and how steeply?

 

[Bruce B]

Hi Bruce,

Interesting...Where do you crossover your main speakers and how steeply?

approx 94Hz with a slow 6dB/Octave slope. Yes, the CR-1 has been modded to a 3 and 6dB slope

 

[Minnesotafats]

Generally I would say go with at least two subs with a lower crossover setting than you would think IF you have a room that is big enough. Generally subs are harder to implement properly the smaller the room. I technically have 2 stacks of three subs for each channel in a very large room. 32Ft by 38ft by 10 ft ceiling on average.

 

[DonH50]

One thing often overlooked is how high the distortion gets with many (certainly not all) speakers driven by large bass signals. Remember our hearing (see equal loudness curves) is such that it takes 100x to 1000x or more the power in the deep bass (subwoofer'ish) range to sound as loud as the midrange, and despite larger longer-throw drivers, distortion gets high for many speakers in that scenario. I designed my first DIY servo sub because my Maggies simply could not handle deep, loud bass (MG-I and later MG-IIIa, though I ended up doing similar things for friends with MG-20's though they did better). A number of conventional speakers through the years had high distortion as well, though not as high as the Maggies or 'stats I played with. I don't have measurements for many speakers these days, and certainly not of the WBF class, but the general trend seems to hold true. I am pretty sure my current speakers (Revel Salon2) would do decently, but as usual placing them for best imaging and such is not best for room modes, thus the subs.

Subs always lead to big pro/con debates, such is life.

Sorry if my posts have appeared dogmatic or dismissive, not my intent. And I should have noted that my first post included my notes from 20+ years ago. - Don

 

[LL21]

approx 94Hz with a slow 6dB/Octave slope. Yes, the CR-1 has been modded to a 3 and 6dB slope

Thank you and good to bear in mind...with a slope like that, I suspect you have definitely done your homework (as usual) and blended them very very carefully.

 

[LL21]

One thing often overlooked is how high the distortion gets with many (certainly not all) speakers driven by large bass signals. Remember our hearing (see equal loudness curves) is such that it takes 100x to 1000x or more the power in the deep bass (subwoofer'ish) range to sound as loud as the midrange, and despite larger longer-throw drivers, distortion gets high for many speakers in that scenario. I designed my first DIY servo sub because my Maggies simply could not handle deep, loud bass (MG-I and later MG-IIIa, though I ended up doing similar things for friends with MG-20's though they did better). A number of conventional speakers through the years had high distortion as well, though not as high as the Maggies or 'stats I played with. I don't have measurements for many speakers these days, and certainly not of the WBF class, but the general trend seems to hold true. I am pretty sure my current speakers (Revel Salon2) would do decently, but as usual placing them for best imaging and such is not best for room modes, thus the subs.

Subs always lead to big pro/con debates, such is life.

Sorry if my posts have appeared dogmatic or dismissive, not my intent. And I should have noted that my first post included my notes from 20+ years ago. - Don

Very very interesting...intuitively, Don, I have been really thinking about next major move and I keep coming back to 2 subs, each with 2 x dual-opposing 18" cones...which create the equivalent air displacement of something 7 Velodyne DD18+s or comparable to the Genesis Prime dual sub towers with something like 12 x 12" cones per side.

Very very low distortion, high air displacement. Based on your own [extensive] experience...does this seems like a reasonable target for all-out low distortion, foundational bass (not a night club at all) for a room that is 40' x 17' x 11' to be driven by something like 10K watts of A/B power (also designed by the sub manufacturer in a separate chassis)...below 38hz...alongside the Wilson XLFs?

 

[gleeds]

Generally I would say go with at least two subs with a lower crossover setting than you would think IF you have a room that is big enough. Generally subs are harder to implement properly the smaller the room. I technically have 2 stacks of three subs for each channel in a very large room. 32Ft by 38ft by 10 ft ceiling on average.

Al, if I remember correctly, the JL Audio subs have continuous phase adjustment? I know the top-of-the-line Gotham has continuous phase adjustment.

I do think this is one advantage the JL subs and the Von Schweikert Audio Shockwave subs have over REL which has only a fixed option of zero or 180°.

Ron, having done four shows with Von Schweikert using their Shockwave 12 subs, as well as experiencing some of the finest sound I have yet to experience in the demo room at Scott Walker Audio using dual Shockwave subs combined with the VSA Ultra 7 speakers, I am convinced by their efficacy. This is even true with full-range speakers like their Ultra 7s, which deliver low 20s response at high levels. The combination of reduced strain on the main towers and especially the use of the subs to dial out annoying room modes afford performance improvement far above their relatively modest cost.

I agree with Steve that this is somewhat room-dependent. Steve has a purpose-built listening room acoustically engineered for his high-performance listening requirement, so adding subs may have exasperated things. His room does have excellent bass! Smaller rooms may benefit even more than larger ones, where large speakers can excite room modes more than usual. Proof positive was a standard hotel room at Axpona, which was made to sound great simply by using a set of 10" subs strictly for room mode cancellation.

I imagine other high-quality brand subs can offer similar improvements if applied correctly in this manner.

 

[DonH50]

Very very interesting...intuitively, Don, I have been really thinking about next major move and I keep coming back to 2 subs, each with 2 x dual-opposing 18" cones...which create the equivalent air displacement of something 7 Velodyne DD18+s or comparable to the Genesis Prime dual sub towers with something like 12 x 12" cones per side.

Very very low distortion, high air displacement. Based on your own [extensive] experience...does this seems like a reasonable target for all-out low distortion, foundational bass (not a night club at all) for a room that is 40' x 17' x 11' to be driven by something like 10K watts of A/B power (also designed by the sub manufacturer in a separate chassis)...below 38hz...alongside the Wilson XLFs?

I'm not a speaker designer, and my grad courses in acoustics were long ago, so take anything I say with a block of salt. And I have not done professional analysis for 10+ years now. Unfortunately experience does not always go hand-in-hand with competence (*).

My last significant experience with Wilson was long ago and the Alexandria XLF costs more than my house when we built it. Looking at their specs and the Stereophile review is interesting; the bass response has a large peak, but John noted it is due to the near-field measurement, so I do not know their "true" response. It looks like the big port is tuned to ~19 Hz, pretty low, but should augment the bass to and a little below that point. JA later indicates they have extended response to below 20 Hz, so to me subs would be to counter room modes, and perhaps get another octave into the low organ and percussive range. Too bad he does not measure distortion though he said he expects it to be low. The XLF ports both woofer(s) and midrange drivers, a fairly unique feature, I think.

10 kW sounds like a lot of power, especially class AB, but a pair of dual-opposed 18" subs properly placed and integrated should certainly be "a reasonable target". Your room is near a 2:1 L/W ratio so modes could be an issue. Hopefully you are not sitting right in the middle of the room; a sealed rectangular room has a primary mode (null) right in the center. I usually prefer ~1/3 or ~2/3 positions for listening. If you are planning to place the subs physically beside the XLF's that may or may not be optimal depending upon where they sit -- I assume they are out in the room a ways? You could check out Todd Welti's paper on sub positioning for some insight: https://www.harman.com/documents/multsubs_0.pdf

That is a fairly large room; is it sealed, or open to the rest of the house?

In my system, in a fairly small room, I went with four smaller (12") subs for more flexibility in placement and ability to smooth the response. I do not need the output (more than enough from the little quartet), but having multiple subs scattered around provides flatter in-room response. My response is -3 dB at 7 Hz, but there are some significant peaks and valleys I cannot eliminate due to room size, wall boundaries, and so forth.

I did laugh at "foundational bass"; a pair of those subs paired with the XLFs should crack most foundations!

HTH - Don

(*) Experience comes from making lots of mistakes; wisdom is learning from them. So far, I've lots of experience... - me

 

[Kingrex]

In another thread, Atmasphere talked about a swarm. JR of Wallytools is a pro at setting up swarms. JR directed me to a manufacturer of sub cabinets. Its a cabinet and driver. No amp. He then showed me a pro audio multi speaker crossover. He then said get any 200watt or more amps I want. Class my choice.

JR uses tools. Software ro get the subs dialed in. I'm pretty sure he prefers 4 cabinets in the room.

I have been told by others the crossover and amp in the sub cabinet is a disaster. The damage I heard removed from my speakers by remote mounting the crossover makes me think there is something to this.
.
I also think I may need an analog active crossover to cut off the main speakers at some frequency. I guess I am ok with this if its a analog unit.

I hope to have the parts here before the Pac Audio Fest. Then JR can set it up. Not sure I will. So much on my plate.

 

[Kingrex]

A good friend of mine uses his ACCH with ORC room correction to control his subs. He sets the levels flat and the volume quite high. The ORC software integrates the subs. He says it's super simple. Better than he could do by listening. And it takes next to no time to complete the setup. His subs are very well integrated.

 

[Holmz]

In another thread, Atmasphere talked about a swarm. JR of Wallytools is a pro at setting up swarms. JR directed me to a manufacturer of sub cabinets. Its a cabinet and driver. No amp. He then showed me a pro audio multi speaker crossover. He then said get any 200watt or more amps I want. Class my choice.

JR uses tools. Software ro get the subs dialed in. I'm pretty sure he prefers 4 cabinets in the room.

I have been told by others the crossover and amp in the sub cabinet is a disaster. The damage I heard removed from my speakers by remote mounting the crossover makes me think there is something to this.

Which crossover?

I also think I may need an analog active crossover to cut off the main speakers at some frequency.

“Cut off” may be slightly misphrased.
You probably want to gracefully hand off the low end.

I guess I am ok with this if its a analog unit.

I am in the analogue HPF camp, but I do not have high sample rate digital.
And it is simpler to keep the high frequency stuff analogue.

Do you have an analogue HPF in mind?

I hope to have the parts here before the Pac Audio Fest. Then JR can set it up. Not sure I will. So much on my plate.

Well you can get an analogue “High Pass Filter” (HPF), or you can try doing it digitally.
Or one can do an analogue HPF, and just some digital on just the sub woofer.

But if one’s speakers need DIRAC, or some other correction going on, then all digital sort of is in the running.

 

[sigbergaudio]

@Danielaruso I recently posted a method to measure your in room bass response without any special hardware or software.

I think doing so would be very informative of your situation. Might be interesting to do it twice, once with only speakers playing and once with the subs active.

https://www.whatsbestforum.com/threads/easily-measure-and-calibrate-bass-subwoofers-speakers-without-rew-and-microphone-a-guide.39003/

 

[sbnx]

In another thread, Atmasphere talked about a swarm. JR of Wallytools is a pro at setting up swarms. JR directed me to a manufacturer of sub cabinets. Its a cabinet and driver. No amp. He then showed me a pro audio multi speaker crossover. He then said get any 200watt or more amps I want. Class my choice.

JR uses tools. Software ro get the subs dialed in. I'm pretty sure he prefers 4 cabinets in the room.

I have been told by others the crossover and amp in the sub cabinet is a disaster. The damage I heard removed from my speakers by remote mounting the crossover makes me think there is something to this.
.
I also think I may need an analog active crossover to cut off the main speakers at some frequency. I guess I am ok with this if its a analog unit.

I hope to have the parts here before the Pac Audio Fest. Then JR can set it up. Not sure I will. So much on my plate.

So, are you intending to use DSP to integrate the subs? Are you going to roll off your mains or bring in the subs under them?

 

[Brucemck2]

I think one should start with considering WHY one is adding subs. What are you trying to achieve?

More bass? Deeper frequency response? More sense of ambience / immersiveness / sense of room? More even bass response?

It could be one or many of the above.

Good integration and full potential requires high pass, measurements, equalizing and competence to get it all set up correctly for that specific room and setup.

Spot on.

 

[Tangram]

Spot on.

Fair comment but I’d add that listeners tend to become acclimated to the sound of their systems, to the point they don’t actually realize what they’re missing. That was my recent experience at least. Now, with properly set up subs the overall sound draws me more into the music than sans subs.

 

[Kingrex]

This is the processor. The 3 6

Protēa™ SP-series dsp loudspeaker processors - ashly

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ashly.com

This is the speaker.
https://jamesromeyn.com/speakers/subwoofers/debra/

I don't yet know how I would role the main speaker signal off. I'm not that far into it yet.

I don't know the amps yet either. Probably a class D.

I really don't know, but m gut says you don't need to send a fortune to blend subs. I see JL and REL and others offer very expensive models. Yet I'm not hearing they do any better than a very affordable SVS. I believe its going to come down to positioning the subs and dialing in the subs. And a reasonable expectation of them. I will probably start with a pair.

Anyone got a good class D amp suggestion. And a good way to role off the mains. Where is Carlos. Did someone kick him off the Forum? He uses autoformers of something of the sort. I don't want to go crazy. All I'm trying to do is roll the bottom. I'm not bi or tri amping.

 

[Lagonda]

Generally I would say go with at least two subs with a lower crossover setting than you would think IF you have a room that is big enough. Generally subs are harder to implement properly the smaller the room. I technically have 2 stacks of three subs for each channel in a very large room. 32Ft by 38ft by 10 ft ceiling on average.

But your main speakers where not designed to play lower than 100 Hz, the sub towers where designed with similar material drivers and the crossover is very adaptable especially on Mk 2 versions.

 

[Hear Here]

Anyone got a good class D amp suggestion. And a good way to role off the mains. Where is Carlos. Did someone kick him off the Forum? He uses autoformers of something of the sort. I don't want to go crazy. All I'm trying to do is roll the bottom. I'm not bi or tri amping.

If you are looking for an amp that offers bass cut off to the main speakers, take a look at the NAD M33. Its Settings allow for a roll-off of your choice between 40 and 200 Hz and (if you tell the amp you are using 1 or 2 subs), the pre-outs are set to match. So if 80 Hz is selected, you main speakers will be protected from those lower frequencies and the pre-outs to the subs will get only those low frequencies.

The new NAD M66 preamp goes a stage further with its 4 dedicated sub outs (single ended and balanced) and these can be tailored for room acoustics via the built-in Dirac Live Bass Control. I'm likely to get this preamp and look forward to trying that particular feature - if I keep my subs!

The M33 uses Purifi Eigentakt Class D technology, but that's to its speaker sockets. If looking for good Class D power amp for subs, the NAD M23 or Atma-Sphere Class D monos may be worth investigating. However most subs seem to include their own Class D amps that are typically 500 - 1000 watts - the ones I mentioned are lower powered.

 

[ptman]

I have YG Carmels (original version) with twin REL S/3s. Room is 12.5 x 17 x 10. I have the REL's inside of, and slightly in front of, the midrange of the Carmel. I'm not a fan of big bass, and believe they provide a solid underpinning for the sound, and allow a larger soundstage to emerge from the Carmels.

 

[DonH50]

@Danielaruso I recently posted a method to measure your in room bass response without any special hardware or software.

I think doing so would be very informative of your situation. Might be interesting to do it twice, once with only speakers playing and once with the subs active.

https://www.whatsbestforum.com/threads/easily-measure-and-calibrate-bass-subwoofers-speakers-without-rew-and-microphone-a-guide.39003/

This is neat, I have not used a phone app! I do want to highlight that @sigbergaudio noted most phone apps are limited in low frequency response, as are most SPL meters. C weighting rolls off at 30 Hz and below so is not accurate for deep subwoofer frequencies. It sounds like a great method for matching levels at the crossover frequency, where it is most important.

This may already be in the article (I only quickly skimmed), but you can play a tone at the crossover frequency with the phone (SPL meter) at the listening position, with sub and mains playing. Adjust the sub's phase for maximum SPL; that should be when subs and mains are in phase. Then adjust sub level(s) appropriately.