2-Channel Subwoofer Integration

LenWhite

Well-Known Member
Feb 11, 2011
424
67
375
Florida
systems.audiogon.com
Barry Ober has more than 35 years research into the best methodology for the easiest and most comprehensive subwoofer integration and system alignment, including speaker imaging.

I've read most of his website and used his techniques to integrate my JL Audio F212v2 with my 2-channel system. Bass dynamics, imaging, and clarity are significantly better than any 2-channel system I've experienced at RMAF, Audio showrooms, or in my home. All but a very few ported speaker systems with separate bass towers should have subwoofers to experience evocative low frequency bass.

The following are excerpts from his extensive website: (The Sound Doctor)

A ported speaker is ALWAYS nothing more than a cheap way to attempt to get free bass out of an enclosure and /or driver that's too small. It's a holdover from the 1930's when because of driver inefficiencies (especially when compared to today's units) you had to do everything possible to increase the useable output over the desired range of low frequencies.

When the manufacturer of a speaker cabinet defines the frequency response (i.e., 37 Hz - 20kHz +/- 3dB) this is what is defined by the entire arrangement of the port and the air in the cabinet and the driver. At some low frequency the port air is exactly out of phase with the driver air pressure and since they cancel, there is NO output from the cabinet into the room. Therefore with a ported cabinet, the entire sloppy concept is this juggling game between the response of the drivers under air pressure, the passive crossover inside the box, the port size and placement.

Simply connecting a sub to existing mains speaker (or amp) terminals is the WORST POSSIBLE WAY to do this. EVERYTHING scientific and acoustic about this method is wrong, from the additive delay issues to the back EMF of the mains affecting the LF signal. However there are plenty of people who simply do not understand correctly integrated bass, and they will be reasonably happy simply sticking another box on to their system without regard to timing, phase and frequency issues, and they will think it sounds "ok" or "good" and for those people it doesn't really matter.

Some audiophiles don't want to introduce yet another active "thing" in their precious signal path, not realizing that adding the crossover is very much the lesser of two evils.

Actually adding a crossover is really a WIN-WIN situation:

WIN # 1) Since you are now NOT putting in 20 Hz - 80 Hz into the mains you are not using up the available LF cone movement with bass, so the LF cone in your mains is able to play its higher freqs (up to IT'S crossover point) much more cleanly. You get an apparent 6dB or more dynamic range. You can play your system LOUDER, and also with less compression distortion in the LF driver when you're having that Saturday night dance party and you're playing urban bass technopop at 110+ dB. Really.

WIN # 2) Since you are not putting bass into that same driver you are not Doppler modulating everything between 80 and 600, or whatever the next crossover point is. This means cleaner mids. By far.

WIN #3) You are not sucking current out of your main power amp at low frequencies, so there is more current reserve to play those highs louder...

WIN # 4) Since the cones aren't moving as far at the low freqs the driver itself is not generating as much back EMF therefore the damping factor and all of its issues are greatly negated. And you don't need to run silver plated cold water pipes to your mains as speaker wires because there is less current draw by the speakers.

WIN # 5) Freqs below 80 are now NOT causing transient intermodulation distortion with the higher freqs (and vice versa) in your power amp. Cleaner still.​

If you have a 2-channel only system if you do not correctly use a crossover you are both wasting your time and you will be frustrated.

If your speakers are ported, you SHOULD close (seal) the ports. Towels will do for a test but you might consider purchasing a 3", 4", or 5" thick slab of "foam" at a notions / sewing store. What you are trying to accomplish is to NOT have multiple sources of differing phase relationships (the main driver, the port air, and the sub driver) at or near the crossover frequency.

Invert the polarity of the MAIN speaker the sub is CLOSEST TO. Disconnect all the other speakers in the room. Place your head equidistant between the sub and the speaker it is closest to. Play the 80 Hz tone. Adjust the phase control AND the level control and both settings of the polarity switch until you hear a distinct NULL. (IT MIGHT EVEN DISAPPEAR COMPLETELY) There should be some setting of the two controls on the JL sub which will provide a rather sharp null - this is a CRITICAL setting and you might find it to be very sharp. Now put the wiring back the correct way to that one speaker. Reconnect the other speaker and you're done.
 
  • Like
Reactions: MTB Vince

Atmasphere

Industry Expert
May 4, 2010
1,575
914
495
St. Paul, MN
www.atma-sphere.com
The best bass I've encountered with a 2-channel system is with the use of something called a Distributed Bass Array. This is the use of (at least) four subs, placed asymmetrically in the room so as to break up standing waves. Standing waves are common in regularly dimensioned rooms. This is because the bass frequencies (at 80Hz the bass waveform is about 14 feet) can bounce off of walls and arrive back at the listening chair with plenty of energy to cancel out the incoming bass signal at certain frequencies, depending on the size of the room and the placement of the listening position.

By placing the subs asymmetrically, you get lots of much smaller peaks and valleys, evenly distributed about the room. Since the bass waveform is so long below 80 Hz, unless you have an enormous room, within 2 iterations of 80Hz the bass is entirely reverberant. For this reason usually 80Hz and below can be driven with a mono signal.

The trick is to make sure the subs do not attract attention to themselves- so they should be crossed over enough below 80Hz that the main speakers convince you that the bass sound is coming from in front of you- by the harmonics of the bass instruments.
 

ecwl

Member
Mar 20, 2021
38
29
18
I have to admit I agree with what was said but also strongly disagree with what has been said. The more I play around with my audio system and listen to others and started getting myself into digital room correction, the more I’ve come to the conclusion that all our audio systems are compromises, from the room, the room treatment, our seating and speaker positions, the aesthetics of our system, electronics, speakers, digital vs vinyl, etc.

So I think adding an analog crossover between the speakers and the subwoofer(s) definitely provides all the benefits already mentioned but the trade off is that the analog crossover always causes some loss of transparency. Unfortunately, most of us don’t want to take our CD transport, feed the digital signal into a digital crossover to split it into two high-end DACs, two preamps, and then into the amp+speakers and subwoofers. Because I guarantee you if your system were setup this way instead of with the analog crossover, you’ll easily be able to hear the loss of transparency from the analog crossover. So ultimately, using an analog crossover is a trade-off between getting that perfectly integrated subwoofer to speaker transition in frequency and phase response while accepting a subtle loss of transparency from the crossover. And it is true in most systems, the trade-off is worth it. I know many people who insist that they can’t hear any loss of transparency from their crossover. If you can’t hear it in your system, great.

Similarly, distributed bass array is a trade-off between getting a much better and flatter frequency response in the bass region and losing transient accuracy in the bass sound. But as mentioned before, most speakers are ported and most rooms have significant bass resonance issues so most of us are actually completely used to blurred bass transients. I think once again, this is why most of us would prefer the better and flatter frequency response from distributed bass array and be willing to ignore the slight loss in transient accuracy in bass sound. I also know many people who claim that there is no alteration in transient accuracy in bass sound with distributed bass array. If you can’t hear it in your system, great.

IMHO, sadly, there is no perfect or best. There are just compromises. Fortunately, they pretty much all sound great when well setup. And to me, once it’s well setup, it’s easy to ignore the compromises.
 

Atmasphere

Industry Expert
May 4, 2010
1,575
914
495
St. Paul, MN
www.atma-sphere.com
My main speakers are flat to 20Hz. So I didn't need to run 4 subs- only 2. And since the mains are flat to 20Hz, no worries about a crossover (I agree they can be 'resolution filters'). Instead I run a balanced line to my subwoofer amplifier and it does everything for the two subs. My main amps get the signal directly from the preamp. No loss in transient energy as far as I can tell- using LPs that I recorded.
 

stehno

Well-Known Member
Jul 5, 2014
1,304
262
240
Salem, OR
Barry Ober has more than 35 years research into the best methodology for the easiest and most comprehensive subwoofer integration and system alignment, including speaker imaging.

I've read most of his website and used his techniques to integrate my JL Audio F212v2 with my 2-channel system. Bass dynamics, imaging, and clarity are significantly better than any 2-channel system I've experienced at RMAF, Audio showrooms, or in my home. All but a very few ported speaker systems with separate bass towers should have subwoofers to experience evocative low frequency bass.
That's not necessarily saying all that much. First off, many don't even understand what a superior bass should sound like. And for those few who do, it can often times take weeks or even months to get things dialed in. In my case, sometimes years. Exhibitors at audio shows generally have 2 or 3 days tops to prepare for a show from the ground up and they've usually got about 20 things on their plates that need to get done and done well and a superior bass is just one of them. So for some who know what they're doing, they must compromise. For other exhibitors, it very well could be the same type of bass they're used to hearing back at the shop and it's always just barely good enough or worse.

The following are excerpts from his extensive website: (The Sound Doctor)

A ported speaker is ALWAYS nothing more than a cheap way to attempt to get free bass out of an enclosure and /or driver that's too small. It's a holdover from the 1930's when because of driver inefficiencies (especially when compared to today's units) you had to do everything possible to increase the useable output over the desired range of low frequencies.
Most musical bass I've ever heard came from a pair of full-range (down to about 23Hz) ported speakers without subwoofers. Yes, there are those who can go deeper but I've yet to hear anything quite as musical as those for their given range with ports.

When the manufacturer of a speaker cabinet defines the frequency response (i.e., 37 Hz - 20kHz +/- 3dB) this is what is defined by the entire arrangement of the port and the air in the cabinet and the driver. At some low frequency the port air is exactly out of phase with the driver air pressure and since they cancel, there is NO output from the cabinet into the room. Therefore with a ported cabinet, the entire sloppy concept is this juggling game between the response of the drivers under air pressure, the passive crossover inside the box, the port size and placement.
This does not necessarily imply he's correct and others are wrong. There are a number of variables involved and ports / sealed are just one of them.

Simply connecting a sub to existing mains speaker (or amp) terminals is the WORST POSSIBLE WAY to do this. EVERYTHING scientific and acoustic about this method is wrong, from the additive delay issues to the back EMF of the mains affecting the LF signal. However there are plenty of people who simply do not understand correctly integrated bass, and they will be reasonably happy simply sticking another box on to their system without regard to timing, phase and frequency issues, and they will think it sounds "ok" or "good" and for those people it doesn't really matter.
100% agree. Especially with the high-level inputs which sounds really keen on the surface. But once given any thought whatsoever, it's some of the most lame logic I've witnessd in high-end audio.

Some audiophiles don't want to introduce yet another active "thing" in their precious signal path, not realizing that adding the crossover is very much the lesser of two evils.​
As a fundamentalist, I certainly don't. But I eventually gave up trying to get my speakers to acoustically couple with the room so I had to introduce a subwoofer into the mix. Which is a whole new bag of potential bass issues. But it can be done.

Actually adding a crossover is really a WIN-WIN situation:

WIN # 1) Since you are now NOT putting in 20 Hz - 80 Hz into the mains you are not using up the available LF cone movement with bass, so the LF cone in your mains is able to play its higher freqs (up to IT'S crossover point) much more cleanly. You get an apparent 6dB or more dynamic range. You can play your system LOUDER, and also with less compression distortion in the LF driver when you're having that Saturday night dance party and you're playing urban bass technopop at 110+ dB. Really.

WIN # 2) Since you are not putting bass into that same driver you are not Doppler modulating everything between 80 and 600, or whatever the next crossover point is. This means cleaner mids. By far.

WIN #3) You are not sucking current out of your main power amp at low frequencies, so there is more current reserve to play those highs louder...

WIN # 4) Since the cones aren't moving as far at the low freqs the driver itself is not generating as much back EMF therefore the damping factor and all of its issues are greatly negated. And you don't need to run silver plated cold water pipes to your mains as speaker wires because there is less current draw by the speakers.

WIN # 5) Freqs below 80 are now NOT causing transient intermodulation distortion with the higher freqs (and vice versa) in your power amp. Cleaner still.​
I suspect much of this depends on system configurations and tuning. I have full-range mains but their bass is perhaps their weakest link. Nevertheless, my subs and main woofer work in unison from about 30Hz to 80Hz. Not my plan as I would prefer no subwoofers but in this config it seems to work rather well for me.

If you have a 2-channel only system if you do not correctly use a crossover you are both wasting your time and you will be frustrated.
Perhaps. I've never used an active cross-over but I've wasted/spent much time and frustration getting my subs dialed in. Well, 1 sub anyway. Recently acquired a 2nd sub and now neither is dialed-in very well. But it's well enough for now.

If your speakers are ported, you SHOULD close (seal) the ports. Towels will do for a test but you might consider purchasing a 3", 4", or 5" thick slab of "foam" at a notions / sewing store. What you are trying to accomplish is to NOT have multiple sources of differing phase relationships (the main driver, the port air, and the sub driver) at or near the crossover frequency.
Considering that achieving a superior bass potentially requires some black magic, I'd be hesitant about being too dogmatic about a single source. After all, everybody's experience is limited. Including the supposed guru's.

Invert the polarity of the MAIN speaker the sub is CLOSEST TO. Disconnect all the other speakers in the room. Place your head equidistant between the sub and the speaker it is closest to. Play the 80 Hz tone. Adjust the phase control AND the level control and both settings of the polarity switch until you hear a distinct NULL. (IT MIGHT EVEN DISAPPEAR COMPLETELY) There should be some setting of the two controls on the JL sub which will provide a rather sharp null - this is a CRITICAL setting and you might find it to be very sharp. Now put the wiring back the correct way to that one speaker. Reconnect the other speaker and you're done.
Interesting. Thanks for sharing.
 

MTB Vince

Well-Known Member
May 11, 2019
160
153
113
58
Dundas, ON Canada
Years of mucking about with subwoofers to varying degrees of semi-success eventually led me down the path Barry Ober champions and @LenWhite quotes above. Sealed box ATC mains, the JL Audio CR-1 (most transparent subwoofer crossover ever?), and a quartet of sealed box Seaton subwoofers- all set up very much in the fashion Barry suggests but also with the four identical subs arranged around the room in the Distributed Bass Array @Atmasphere mentioned. The sum of these components and methods, dialed in with iterative placement and REW measurements, a touch of DSP time alignment and PEQ seasoning applied only to the subs, and final tweaking by ear has brought me to another place entirely. The best sounding truly full range bass and most satisfying overall sound I've achieved to date. Amen Barry!
 

Robh3606

Well-Known Member
Aug 25, 2010
1,274
268
465
Destiny
The following are excerpts from his extensive website: (The Sound Doctor)

A ported speaker is ALWAYS nothing more than a cheap way to attempt to get free bass out of an enclosure and /or driver that's too small. It's a holdover from the 1930's when because of driver inefficiencies (especially when compared to today's units) you had to do everything possible to increase the useable output over the desired range of low frequencies.

When the manufacturer of a speaker cabinet defines the frequency response (i.e., 37 Hz - 20kHz +/- 3dB) this is what is defined by the entire arrangement of the port and the air in the cabinet and the driver. At some low frequency the port air is exactly out of phase with the driver air pressure and since they cancel, there is NO output from the cabinet into the room. Therefore with a ported cabinet, the entire sloppy concept is this juggling game between the response of the drivers under air pressure, the passive crossover inside the box, the port size and placement.

Well I have to take exception to this.

Paragraph one is clearly opinion which is fine. We all have one, I don't agree as it's not free bass. It's another type of alignment that doesn't waste the energy from the back of the cone. You can also use a box program and tune to get your desired bass curve so much more flexibility vs. sealed plus a significant gain in output.

Paragraph 2

No output from the cabinet?? Measurement's do not back that assertion up. The driver and port act in tandem all you have to do is look at the summed response. Look at measurements both anechoic or gated and summed speaker and port. Here is a separate then summed from Stereophile and anechoic of JBL Array 1400.

The first is the response showing the woofer Blue and port Red then the second summed. Last is anechoic so summed no measurement artifacts which in this case is the rising bass response hump.

Where is the no output from the cabinet?? There is no null in the summed output of a properly designed reflex cabinet.



Rob :)
 

Attachments

  • 510JBLfig3 (1).jpg
    510JBLfig3 (1).jpg
    40.1 KB · Views: 3
  • 510JBLfig4 (1).jpg
    510JBLfig4 (1).jpg
    32.8 KB · Views: 3
  • 1400 Array pg 04.jpg
    1400 Array pg 04.jpg
    179.8 KB · Views: 3

Robh3606

Well-Known Member
Aug 25, 2010
1,274
268
465
Destiny
I took that to mean that the cabinet itself wasn't vibrating. But its a good question- since the text is really open to interpretation, or that other thing, misinterpretation.

Hello

"At some low frequency the port air is exactly out of phase with the driver air pressure and since they cancel, there is NO output from the cabinet into the room."

I took that to mean there was a null at some point with from the cabinet with the port and driver summed. Cabinets will always vibrate sealed or ported. You are correct language can be tricky as we both read it differently.

Rob :)
 
Last edited:

sbnx

Well-Known Member
Mar 28, 2017
636
478
155
I am of the opinion that subwoofers add a great deal to the presentation. Not only low end extension (below 40Hz) but more importantly a sense of acoustic space. A pair of subs just makes the presentation much larger with a sense of envelopment. Once you understand how to setup a single or pair of subs and which tools are necessary in each situation it is not very hard and can be done in a couple hours.

Audio in the room is always about trade off's. As an example, do you think that the transparency loss of the CR-1 is worth the enhanced bass performance and greater sense of space? However, with enough time and patience you may be able to find a solution that gives both without the compromise but may compromise something else (e.g. aesthetics).
 

LL21

Well-Known Member
Dec 26, 2010
13,129
1,519
658
I am of the opinion that subwoofers add a great deal to the presentation. Not only low end extension (below 40Hz) but more importantly a sense of acoustic space. A pair of subs just makes the presentation much larger with a sense of envelopment. Once you understand how to setup a single or pair of subs and which tools are necessary in each situation it is not very hard and can be done in a couple hours.

Audio in the room is always about trade off's. As an example, do you think that the transparency loss of the CR-1 is worth the enhanced bass performance and greater sense of space? However, with enough time and patience you may be able to find a solution that gives both without the compromise but may compromise something else (e.g. aesthetics).
100% agree with my experience of 1 sub. Would love to do dual...and that might actually be our next major focus...
 

Atmasphere

Industry Expert
May 4, 2010
1,575
914
495
St. Paul, MN
www.atma-sphere.com
Hello

"At some low frequency the port air is exactly out of phase with the driver air pressure and since they cancel, there is NO output from the cabinet into the room."

I took that to mean there was a null at some point with from the cabinet with the port and driver summed. Cabinets will always vibrate sealed or ported. You are correct language can be tricky as we both read it differently.

Rob :)
Hard to imagine no output at a certain frequency... I'd like to see the measurement for that. My main speakers are ported and their output is flat at 20Hz with plenty of output at 16Hz. There is no point above that at which their output is zero, until you are well into the +30KHz region ;)
 

microstrip

VIP/Donor
May 30, 2010
18,805
3,126
810
Portugal
Barry Ober has more than 35 years research into the best methodology for the easiest and most comprehensive subwoofer integration and system alignment, including speaker imaging.

I've read most of his website and used his techniques to integrate my JL Audio F212v2 with my 2-channel system. Bass dynamics, imaging, and clarity are significantly better than any 2-channel system I've experienced at RMAF, Audio showrooms, or in my home. All but a very few ported speaker systems with separate bass towers should have subwoofers to experience evocative low frequency bass.

The following are excerpts from his extensive website: (The Sound Doctor)

A ported speaker is ALWAYS nothing more than a cheap way to attempt to get free bass out of an enclosure and /or driver that's too small. It's a holdover from the 1930's when because of driver inefficiencies (especially when compared to today's units) you had to do everything possible to increase the useable output over the desired range of low frequencies.

When the manufacturer of a speaker cabinet defines the frequency response (i.e., 37 Hz - 20kHz +/- 3dB) this is what is defined by the entire arrangement of the port and the air in the cabinet and the driver. At some low frequency the port air is exactly out of phase with the driver air pressure and since they cancel, there is NO output from the cabinet into the room. Therefore with a ported cabinet, the entire sloppy concept is this juggling game between the response of the drivers under air pressure, the passive crossover inside the box, the port size and placement.

Simply connecting a sub to existing mains speaker (or amp) terminals is the WORST POSSIBLE WAY to do this. EVERYTHING scientific and acoustic about this method is wrong, from the additive delay issues to the back EMF of the mains affecting the LF signal. However there are plenty of people who simply do not understand correctly integrated bass, and they will be reasonably happy simply sticking another box on to their system without regard to timing, phase and frequency issues, and they will think it sounds "ok" or "good" and for those people it doesn't really matter.

Some audiophiles don't want to introduce yet another active "thing" in their precious signal path, not realizing that adding the crossover is very much the lesser of two evils.

Actually adding a crossover is really a WIN-WIN situation:

WIN # 1) Since you are now NOT putting in 20 Hz - 80 Hz into the mains you are not using up the available LF cone movement with bass, so the LF cone in your mains is able to play its higher freqs (up to IT'S crossover point) much more cleanly. You get an apparent 6dB or more dynamic range. You can play your system LOUDER, and also with less compression distortion in the LF driver when you're having that Saturday night dance party and you're playing urban bass technopop at 110+ dB. Really.

WIN # 2) Since you are not putting bass into that same driver you are not Doppler modulating everything between 80 and 600, or whatever the next crossover point is. This means cleaner mids. By far.

WIN #3) You are not sucking current out of your main power amp at low frequencies, so there is more current reserve to play those highs louder...

WIN # 4) Since the cones aren't moving as far at the low freqs the driver itself is not generating as much back EMF therefore the damping factor and all of its issues are greatly negated. And you don't need to run silver plated cold water pipes to your mains as speaker wires because there is less current draw by the speakers.

WIN # 5) Freqs below 80 are now NOT causing transient intermodulation distortion with the higher freqs (and vice versa) in your power amp. Cleaner still.​

If you have a 2-channel only system if you do not correctly use a crossover you are both wasting your time and you will be frustrated.

If your speakers are ported, you SHOULD close (seal) the ports. Towels will do for a test but you might consider purchasing a 3", 4", or 5" thick slab of "foam" at a notions / sewing store. What you are trying to accomplish is to NOT have multiple sources of differing phase relationships (the main driver, the port air, and the sub driver) at or near the crossover frequency.

Invert the polarity of the MAIN speaker the sub is CLOSEST TO. Disconnect all the other speakers in the room. Place your head equidistant between the sub and the speaker it is closest to. Play the 80 Hz tone. Adjust the phase control AND the level control and both settings of the polarity switch until you hear a distinct NULL. (IT MIGHT EVEN DISAPPEAR COMPLETELY) There should be some setting of the two controls on the JL sub which will provide a rather sharp null - this is a CRITICAL setting and you might find it to be very sharp. Now put the wiring back the correct way to that one speaker. Reconnect the other speaker and you're done.
Len,

I have read the Sounddoctor site and even bought his CD and recipe for sub setting years ago. IMHO quoting excerpts out their context will give people a wrong idea of his work, focusing on details and ignoring the overall.

BTW you inadvertently changed the sense of the quote when you edited it :

A port is ALWAYS nothing more than a cheap way to attempt to get free bass out of an enclosure and /or driver that's too small. It's a holdover from the 1930's when because of driver inefficiencies
(...) https://www.soundoctor.com/whitepapers/subs.htm

I can agree with some readings of this sentence and will disagree with the one you wrote.
 

MTB Vince

Well-Known Member
May 11, 2019
160
153
113
58
Dundas, ON Canada
I am of the opinion that subwoofers add a great deal to the presentation. Not only low end extension (below 40Hz) but more importantly a sense of acoustic space. A pair of subs just makes the presentation much larger with a sense of envelopment. Once you understand how to setup a single or pair of subs and which tools are necessary in each situation it is not very hard and can be done in a couple hours.

Audio in the room is always about trade off's. As an example, do you think that the transparency loss of the CR-1 is worth the enhanced bass performance and greater sense of space? However, with enough time and patience you may be able to find a solution that gives both without the compromise but may compromise something else (e.g. aesthetics).
I did not percieve a loss of transparency with the CR-1 in circuit vs physically bypassed SBNX. And this is the first electronic crossover I've owned and employed in high pass mode which this has been the case with. The Bryston 12B-Sub, a Marchand, a Sumo, and a few others over the years I no longer recall were all disappointing to varying degrees in this regard.
 

LenWhite

Well-Known Member
Feb 11, 2011
424
67
375
Florida
systems.audiogon.com
Audio in the room is always about trade off's. As an example, do you think that the transparency loss of the CR-1 is worth the enhanced bass performance and greater sense of space? However, with enough time and patience you may be able to find a solution that gives both without the compromise but may compromise something else (e.g. aesthetics).

The reduction in vibration smear in the stereo speakers due to Sub-bass being handled by the subwoofer, and the dedication of the stereo amp to those speakers increases the clarity and presence of frequencies >90Hz in my case. I'd say the use of the CR1 is at least an equal trade off.

Sub-bass-16 to 60 Hz
Bass-60 to 250 Hz
 

sbnx

Well-Known Member
Mar 28, 2017
636
478
155
The reduction in vibration smear in the stereo speakers due to Sub-bass being handled by the subwoofer, and the dedication of the stereo amp to those speakers increases the clarity and presence of frequencies >90Hz in my case. I'd say the use of the CR1 is at least an equal trade off.

Sub-bass-16 to 60 Hz
Bass-60 to 250 Hz
LenWhite, Looked at the pics of your room on AG. Very nice. Do you have acoustic measurements of the system from your listening position? I am curious as based on where you have your speakers placed from the front wall (58") you should have a null at about 60Hz. Since your subwoofer is in the same plane as the speakers and you have the crossover set at 75Hz the same null will exist. (Unless you moved the phase knob on the sub up. But then that defeats the purpose of putting the sub in the same plane as the speakers). If the subwoofer were backed up to 45" from the wall then the SBIR will be above the crossover point of 75Hz.

Just food for thought.
 
  • Like
Reactions: christoph

MTB Vince

Well-Known Member
May 11, 2019
160
153
113
58
Dundas, ON Canada
LenWhite, Looked at the pics of your room on AG. Very nice. Do you have acoustic measurements of the system from your listening position? I am curious as based on where you have your speakers placed from the front wall (58") you should have a null at about 60Hz. Since your subwoofer is in the same plane as the speakers and you have the crossover set at 75Hz the same null will exist. (Unless you moved the phase knob on the sub up. But then that defeats the purpose of putting the sub in the same plane as the speakers). If the subwoofer were backed up to 45" from the wall then the SBIR will be above the crossover point of 75Hz.

Just food for thought.
The big RPG Modex Plate bass traps across @LenWhite's front wall should kill the front wall low frequency reflections which would otherwise cause SBIR. Modex Plates offer effective absorption down to low enough frequencies to effectively address SBIR.
 
Last edited:
  • Like
Reactions: christoph

Bruce B

WBF Founding Member, Pro Audio Production Member
Apr 26, 2010
6,883
301
520
Snohomish, WA
www.pugetsoundstudios.com
I was totally against adding subs and x-over. Barry helped me get my system dialed in. I thought he was crazy when he told me to roll off my mains at 80-90Hz... it's a gradual slope, but still.

I'm sold on this idea. It's the best my system has ever sounded.
 
  • Like
Reactions: LenWhite

Duke LeJeune

[Industry Expert]/Member Sponsor
Jul 22, 2013
724
1,105
370
Princeton, Texas
Similarly, distributed bass array is a trade-off between getting a much better and flatter frequency response in the bass region and losing transient accuracy in the bass sound.

The ears cannot detect the presence of bass energy from less than one wavelength, and cannot detect the pitch of bass energy before hearing several wavelengths. So the perceived onset of transients is not a subwoofer frequency phenomenon; it happens much further up the spectrum. To put it another way, perceptually there is no such thing as "first-arrival sound" in the bass region. By the time we hear the bass, the room's effects already are all over it (think of how long bass wavelengths are relative to the reflection paths in typical home audio rooms).

But what the ears CAN detect is, the DECAY of bass energy, which is definitely related to perceived transient response - just not to the ONSET of the transients. You see, in the bass region, speakers + room = a "minimum phase" system, which means that the time-domain response tracks the frequency response. So where there is a peak in the frequency response, there is a corresponding longer decay time in the time domain, which is what muddies the bass transient reponse. The good news is this: In the bass region, once we have fixed the frequency response, we have ALSO fixed the time-domain response! And this is what a distributed multi-sub system does well. It's superior in-room frequency response translates into BETTER transient accuracy in that part of the bass region which DOES matter to the ears, namely, the decay of the notes. But the perceptual onset of the transients happens further up the spectrum.

I hope you don't mind an anecdote from an audio show: At RMAF 2018 we had a veteran cable manufacturer come back to our room several times. He has literally decades of experience, typically attending multiple audio shows per year. We played his reference recording, of "Fanfare for the Common Man", which I think was the same version as on Wilson Audio's demo disc. Anyway he said it was the most natural-sounding reproduction of those tympani he had ever heard, and he specifically mentioned several very big names as being included when he made that sweeping statement. "That's what a tympani sounds like" he said, and then went into detail describing what he was hearing that corresponded with hearing tympani live. Our little distributed multi-sub system in that room was not set up with any consideration given to synchronizing the arrival times; on the contrary, the placement was deliberately asymmetrical and we had the left-hand pair of subs in phase quadrature (phase shifted 90 degrees) relative to the right-hand pair of subs. The transient onset information was being effectively delivered by the mains (which had limited bass response but a big midwoofer and were running full-range), and then the distributed multi-sub system was getting the in-room decay of the bass energy right.

Audio in the room is always about trade off's.

Totally agree.

For instance it, it makes sense to roll off the bottom end of the mains IF the unwanted cone motion is going to introduce audible modulation distortion, and/or overtax the amplifier. But there are "brute force" approaches which make high-pass filtering the mains unnecessary.

The Classic Audio mains that Ralph Karsten ("Atmasphere") uses have twin 15" woofers whose cone motion is negligible even at SPLs that would melt most audiophile speakers. This allows him to add subs without introducing anything into the signal path going to his main speakers. Nor would increasing his amps' headroom by rolling off the bass energy going to the mains make any difference in effective system headroom - his system already has more totally clean headroom than he will ever need.

[quoting Barry Ober] A ported speaker is ALWAYS nothing more than a cheap way to attempt to get free bass out of an enclosure and /or driver that's too small...

Well, not ALWAYS.

Midwoofers which work well in ported boxes have more powerful motors than midwoofers which work well in sealed boxes, which translates into better efficiency and/or better midrange clarity. And if the ported box designer knows what he's doing, the ports can help clean up the midrange relative to the same midwoofers in a sealed box.

Those who take a stance against a technology typically argue against poor implementations of that technology, ignoring the inconveniently good ones. Imo there are too many good ported speakers and too many good sealed-box speakers for THAT characteristic to be what differentiates the good speakers from the bad ones.
 
Last edited:

Atmasphere

Industry Expert
May 4, 2010
1,575
914
495
St. Paul, MN
www.atma-sphere.com
The big RPG Modex Plate bass traps across @LenWhite's front wall should kill the front wall low frequency reflections which would otherwise cause SBIR. Modex Plates offer effective absorption down to low enough frequencies to effectively address SBIR.
They are helpful, but in order to prevent standing waves in the room they would have to dynamically move about the room in order to be in the right place. Put another way, they are about 2% effective as compared to a distributed bass array, which is about 95% effective.

Front wall reflections at bass frequencies can be helpful if the speaker has a downfiring port, downfiring driver or rear facing driver (the word 'can' has emphasis because a lot depends on how high the reflected energy goes and how far the speaker is from the rear wall; if the driver or port has output above 80Hz the speaker might work better if at least 5 feet from the wall behind it...). The energy arriving at the wall behind the speaker is reflected and so is delayed compared to the directly radiated energy. This helps reduce standing wave amplitude although it will not get rid of it entirely.
 

About us

  • What’s Best Forum is THE forum for high end audio, product reviews, advice and sharing experiences on the best of everything else. This is THE place where audiophiles and audio companies discuss vintage, contemporary and new audio products, music servers, music streamers, computer audio, digital-to-analog converters, turntables, phono stages, cartridges, reel-to-reel tape machines, speakers, headphones and tube and solid-state amplification. Founded in 2010 What’s Best Forum invites intelligent and courteous people of all interests and backgrounds to describe and discuss the best of everything. From beginners to life-long hobbyists to industry professionals, we enjoy learning about new things and meeting new people, and participating in spirited debates.

Quick Navigation

User Menu

Steve Williams
Site Founder | Site Owner | Administrator
Ron Resnick
Site Co-Owner | Administrator
Julian (The Fixer)
Website Build | Marketing Managersing