"Wave Launch" and Subwoofer Placement?

LL21

Well-Known Member
Dec 26, 2010
14,411
2,509
1,448
Hi Lloyd,

I would first caution that comparisons of cone area will make for reasonable sanity checks and some quick litmus testing, but there are many variables involved in overall headroom across the spectrum, and most often the correct answer is some version of "it depends." Comparisons are more direct and easier to conceptualize with fully sealed systems, while ports and other acoustic loading augment, extend, or compliment output in more frequency dependent ways, and are harder to dimensionally equate to cone area.

One important understanding to start with is that maintaining the same SPL output at lower and lower frequencies requires 4x the volume displacement for every octave. The relationship is a squared function. Here are two useful practical applications of this reality:
  1. A sealed speaker requires 4x as much excursion to produce 30Hz as it does 60Hz, and 16x more excursion at 20Hz than 80Hz.
  2. In order to produce the same SPL under the same conidtions, an 18" woofer producing 20Hz and a ~5" woofer producing 80Hz will move the same distance in/out.
While surface area is a useful figure to understand, ultimately we care about headroom, distortions, and efficiency to the degree it limits output. In an extreme example we could consider the case of a 6" woofer with 100dB@1W/1m sensitivity and a 15" cone that is only 86dB@1W/1m. The woofer needs 25x the power to match the SPL of the 6", despite the cone area advantage. We really care about the combination of sensitivity at the frequency range of interest (dictated by box size, type, and the woofer), the power available or needed, and what distortions and compression might occur due to limits in power, driver excursion limits, and distortion from the woofer as each are increased. Different approaches with size of woofers, size of enclosures, power, and enclosure type will tend toward specific strengths and characteristics, but there are always outliers and a wide range of performance trade offs.
Surface area is directly related to all of these things, so when you increase surface area you will also raise headroom, lower distortion, increase efficiency and have greater SPL capabilities.

I'm not sure if these measurements covey the entirety of the subjective improvements that having larger woofer surface area bring to the table, but I don't think it's a coincidence that the great majority of speaker manufacturers increase woofer surface area to a massive degree when you look at their cost-no-object systems.

Thank you both, and i think between the many answers, i am starting to get a picture in my mind.

1. Yes, as with speakers, sources, amps (Class A, A/B, Tube, SS, etc), execution is always the ultimate deciding factor in true quality. Any amateur stats, specs are generally no more than guidelines and nice-to-knows

2. That said, understanding some of the fundamentals does provide general direction to those of us who are just starting to investigate

3. For me, it seems clear that from a number of audiophiles with substantial spaces and substantial systems, that deep, effortless bass has correlated with a sense of space, scale and realism that (before being able to reproduce such deep bass), these audiophiles were not able to find an alternative way of reproducing

4. Additionally, (like with Class A amps where heat and weight generally play a big part in the ultimate design), it seems fair to assume that large cones are going to play a part...as clearly evidenced by the Genesis towers, the Thor, the Velodynes, JL Gotham, even the Gryphon tower is SEVERAL 8" inch cones)

5. Setting aside the increased complexity in set up from multiple subs (a big issue no doubt)...the idea of de-pressurizing the sub-bass elements of the system with significant power, significant cone surface area (and P-P movement with all the requisite magnet structures, etc, etc)...seem like a good direction of travel for a SOTA design. This is either many, many smaller cones...or fewer very large cones.

6. Factoring in then the complexity of multi-subs bring...not to mention the fact that our living room will not accommodate multiple sub locations...it then drives us towards fewer subs (perhaps 2)...where by definition then we must look only to much larger cones

7. As a ballpark to start with...and then its about actual displacement of air, etc, etc...it sounds like probably somewhere on the order of 4 x 18" cones is a great place to be ready to start...perhaps 2 x dual-18" subs to keep set up perhaps somewhat more manageable. And if they are exceedingly well designed and then given the correct power, systems for setup/integration perhaps even servo, etc...we have the ability to stick to this (as opposed to up to 6 x 18" cones).

And at this stage...we really get to test the theory of whether this is as much a transformation as others have described in their own systems when their already large speakers were then further reinforced with major sub-bass systems. The one relevant data point for me is that I know I would not do without the Velodyne DD18+ in the system which is one 18" cone, designed by an experienced company, set up by their distributor.
 
Last edited:

Mark Seaton

WBF Technical Expert (Speaker & Acoustics)
May 21, 2010
381
141
390
47
Chicago, IL
www.seatonsound.net
Surface area is directly related to all of these things, so when you increase surface area you will also raise headroom, lower distortion, increase efficiency and have greater SPL capabilities.

I'm not sure if these measurements covey the entirety of the subjective improvements that having larger woofer surface area bring to the table, but I don't think it's a coincidence that the great majority of speaker manufacturers increase woofer surface area to a massive degree when you look at their cost-no-object systems.

No question that more cone area in larger enclosures will always head in the right direction if the woofer and overall design qualities are similar. Less excursion, and less power to produce the same output is usually the most direct path to performance improvements. Within that context we have to remember that woofer characteristics can vary dramatically for the same size cone or same overall cone area (in multiple drivers). We have many cases where different examples of the same diameter woofer or what will make up the same cone area can vary by more than a factor of 3 in linear excursion along with many other dramatic differences related to design priorities, complexity, and of course cost.
 
  • Like
Reactions: DaveC

Mark Seaton

WBF Technical Expert (Speaker & Acoustics)
May 21, 2010
381
141
390
47
Chicago, IL
www.seatonsound.net
Mark Seaton, Duke LeJeune and Others, here is a direct question:

- If we look at how transformational adding a Velodyne DD18+ is to a smaller speaker (as per professional reviews, WBF member experiences including my own) we have a speaker like B&W 805s or the SF Guarneri which has a cone surface area of around 29 square inches per speaker...vs a DD18+ with a cone surface area of 254 square inches (divide by 2 to reflect that the Velodyne is 'split' between the 2 speakers, so 127 square inches)
- This means that this transformation is created by adding a sub that has 4.4x more cone surface area than the main speaker

DIRECT QUESTION: IS IT LOGICAL THEN TO TAKE THIS RATIO AND APPLY IT TO FULL-RANGE SPEAKERS AND "KEEP GOING"? (To avoid room dynamics being a constraint, assume a large room 40' x 20' x 12')

- in other words, taking this ratio to the next logical step, we have a Wilson XLF which is 211 square inches per channel (2 x 1" tweeters, 2 x 7" midranges and 1 x 13" midbass woofer...i assume only the 15" woofer really takes lower bass registers.)
- This means a subwoofer with cone surface area of 924 square inches PER CHANNEL.
- That is basically 4 x 18" woofers per channel or 1018 square inches. (Not far off 6 x dual 15" subs...3 per side (1060 square inches per side)...which legend has it, was something Dan D'Agostino did with his own Wilson X1s years ago)

Quick point of clarification on the differing size woofers in most of the tall Wilson towers. The two woofers operate in the same box and over the same bandwidth. You can see this in various Stereophile review measurements such as these on the XLF, which also confirm the vent tuning to be around 19Hz. The effective woofer is that of the combined 13" and 15" nominal woofers per speaker.

For ported speakers, remember that around that tuning frequency the box and port cause the speaker to have greatly reduced motion where this small motion creates a lot of air movement in the port. This is over a rather limited frequency range, and you can see this in the near field measurements of the XLF and any other ported speaker where they show the overlay of near field response and the summed total. In the measurements of the XLF Figure 3 shows the port output in red overlaid with the woofer's direct output (from the cone) in blue. Note the size of the hump shown here in the 70Hz range was acknowledged as an inaccurate approximation due to measuring in the room and only with near field mathematical combination.
 

Mark Seaton

WBF Technical Expert (Speaker & Acoustics)
May 21, 2010
381
141
390
47
Chicago, IL
www.seatonsound.net
Thank you both, and i think between the many answers, i am starting to get a picture in my mind.

1. Yes, as with speakers, sources, amps (Class A, A/B, Tube, SS, etc), execution is always the ultimate deciding factor in true quality. Any amateur stats, specs are generally no more than guidelines and nice-to-knows

2. That said, understanding some of the fundamentals does provide general direction to those of us who are just starting to investigate

3. For me, it seems clear that from a number of audiophiles with substantial spaces and substantial systems, that deep, effortless bass has correlated with a sense of space, scale and realism that (before being able to reproduce such deep bass), these audiophiles were not able to find an alternative way of reproducing

I have always found that if the addition of very deep extension is sufficiently clean and delivers smooth response at the listening position, the benefits are exactly as you describe with added sense of space, scale, and realism. The qualifier of smooth combined response with the speaker at the listening position is one of the bigger hurdles. Once the response is under control there is then the realization that subtle changes in overall subwoofer level and tilt of the response as it blends with the speakers can make for dramatically different perception of the bass character or quality.

4. Additionally, (like with Class A amps where heat and weight generally play a big part in the ultimate design), it seems fair to assume that large cones are going to play a part...as clearly evidenced by the Genesis towers, the Thor, the Velodynes, JL Gotham, even the Gryphon tower is SEVERAL 8" inch cones)

5. Setting aside the increased complexity in set up from multiple subs (a big issue no doubt)...the idea of de-pressurizing the sub-bass elements of the system with significant power, significant cone surface area (and P-P movement with all the requisite magnet structures, etc, etc)...seem like a good direction of travel for a SOTA design. This is either many, many smaller cones...or fewer very large cones.

6. Factoring in then the complexity of multi-subs bring...not to mention the fact that our living room will not accommodate multiple sub locations...it then drives us towards fewer subs (perhaps 2)...where by definition then we must look only to much larger cones

While there can be some benefit to a column of subwoofers, that difference does reduce as frequency range lowers, and as ceiling height is reduced. For all practical purposes, having a single subwoofer like the DD18+, a larger sub, or a stack of larger subs, they are really all 1 sub location. In the cases where some have used different settings for stacked elements, I'd be very curious to see measurements with them all set the same vs set differently to see what is really going on due to the resulting phase differences.

7. As a ballpark to start with...and then its about actual displacement of air, etc, etc...it sounds like probably somewhere on the order of 4 x 18" cones is a great place to be ready to start...perhaps 2 x dual-18" subs to keep set up perhaps somewhat more manageable. And if they are exceedingly well designed and then given the correct power, systems for setup/integration perhaps even servo, etc...we have the ability to stick to this (as opposed to up to 6 x 18" cones).

And at this stage...we really get to test the theory of whether this is as much a transformation as others have described in their own systems when their already large speakers were then further reinforced with major sub-bass systems. The one relevant data point for me is that I know I would not do without the Velodyne DD18+ in the system which is one 18" cone, designed by an experienced company, set up by their distributor.

For the space you have and capabilities of your speakers, I'm confident there is still significant room to further enhance the system with a more deep bass capability. The fact that you enjoy what your DD18+ adds to your system now only makes this more likely.
 
  • Like
Reactions: Duke LeJeune

LL21

Well-Known Member
Dec 26, 2010
14,411
2,509
1,448
Fantastic Mark, thank you very much. This is quite an exciting area to explore. I have always genuinely enjoyed controlled, deep bass...not as someone who needs to rattle windows for fun. On the contrary, because at low levels (along with a low noise floor), you can listen extremely satisfactorily at 3am while working late and not disturb anyone...and a scaled chest-punch is still there at that low volume. And the sense of venue 'surrounding you' is also there.

The question I am looking forward to answering is does that venue space become more and more tangible as bass power, capability are all massively increased...and much, much lower distortion follows?
 

Duke LeJeune

[Industry Expert]/Member Sponsor
Jul 22, 2013
747
1,200
435
Princeton, Texas
And the sense of venue 'surrounding you' is also there.

The question I am looking forward to answering is does that venue space become more and more tangible as bass power, capability are all massively increased...

In my opinion "bassiousness" (to borrow Todd Welti's word) is not just a matter of how much subwoofage you have... it's also a matter of how you use it. Here are my thoughts on how to get the most bassiousness out of your subs:

In one of his papers acoustician David Griesinger advocates placing subs to the left and right of the listening location and setting their phases 90 degrees apart (in "phase quadrature"). The idea is to simulate the low-frequency phase behavior of a large acoustic space. Since true stereo bass down into the subwoofer region is rare, on most recordings this will enhance the sense of immersion. If the recording does have true stereo bass down into the subwoofer region, then dialing back to in-phase would probably work better for that recording.

The (modest by WBF standards) four-sub system I make normally comes with a single amplifier but as an option two amplifiers can be used, one for the left-hand side of the room and one for the right-hand side of the room, with the phase controls set to 90 degrees apart. These can be left and right channel signals, though ime true stereo bass is rare. Absolute Sound reviewer Robert E. Greene tried this when he reviewed my subwoofer system in 2015 and wrote that

"Adding a second amplifier to drive two of the four subs separately and thus to be able to adjust their gain and phase independently gives potential for even better results. Dave Griesinger has suggested that putting two subs (or sets of subs) on either side of the listener and running them “in quadrature”—90 degrees out of phase—will produce additional spaciousness, and this seems to work extremely well, enhancing the basic Swarm sound.

"This whole spatial effect is not an easy matter to convey in words. But it is easy to hear, striking indeed, and very satisfying."

Obviously this technique can be used with more capable subs than my little guys. I'd love to try this with something like a quartet of Submersives, ideally running them up to 70 or 80 Hz, to take advantage of this effect across as much of the bass region as possible. This implies that the main speakers would not go all the way down, but rather the subs would take over for the bottom couple of octaves or so. My understanding is that the sense of immersion in a large acoustic space - "bassiousness" - is enhanced more by the phase quadrature effect near the top end of the subwoofer range than down at the bottom end, hence my preference for running the subs up fairly high and then rolling them off steeply.

(For the record, Robert Greene is a concert violinist and instructor, and if you watched Russell Crowe play violin in "Master and Commander" you've seen one of his students. By day he's high up in the mathematics department at UCLA where, last I heard, he was working on the nineteen-dimensional mathematics foundation of whatever comes after string theory. He also runs a Doberman Pinscer rescue, so don't give him crap in front of his four-legged friends.)

The phase quadrature setting also addresses an issue which can arise with a distributed multisub system: The modal smoothing effect over most of the bass region has the subs' outputs combining essentially in semi-random phase, but as we get into extremely low frequencies where the wavelengths are long in relation to the room dimensions, there is a transition to essentially in-phase summation. And in-phase summation is louder than semi-random-phase summation, so the result can be too much very low bass, which can sound fat and slow. One solution is to use the above-described phase quadrature technique so that the summation is effectively semi-random phase all the way down. Another is to reverse the polarity of one of the subs. And another would be EQ.

Imo there are other techniques which can enhance the sense of being immersed in the acoustic space of a good two-channel recording, in addition to the "bassiousness" that subwoofers can bring.
 
Last edited:
  • Like
Reactions: VladB

sbo6

VIP/Donor
May 18, 2014
1,659
593
480
Round Rock, TX
Great thread and late to the game. What I didn't read or maybe missed was the relationship between subwoofer output to mains bass output. Specifically, you need more and / or larger driver subwoofers to be able to positively affect the frequency response as mains woofer output increases. Positively = flatten peaks and fill troughs across the bass frequencies.

A second point (IME) is that when tuning 2 channel systems' subwoofer integration, sub placement is critical and incrementally so as room volume decreases. A tower of subwoofers will simply not be as strategically advantaged as multi sub placement even if the top subs are higher off the ground. Real - case example - my room has a >10DB ~30Hz peak that after many attempts can only be tamed by subwoofer placement at / near the right rear room entry. The room shape acts as a horn and with proper setup (phase, ELF, xover freq., etc.) it's possible to mostly flatten this peak. It takes multiple subs at and near that location to effectively "manage" this peak. Another room effect is a dip at ~50Hz which again is only flattened by subs at other locations. The sum effect of all 4 subs each in strategic locations yields a house curve while ameliorating major low freq. peaks and dips. Also, I've experimented with 2 - column JLA subs at or near the mains and the 30Hz peak under all placements exacerbates this peak. WRT subwoofer columns I have heard the Rel 6 - pack and I think it yields positive results primarily because it rolls in at ~25Hz, had it been set for anything significantly higher and you'd likely have bass bloat. At those lower frequencies permitting the mains and subs to play both frequencies is tolerable since a) there's little content that low and b) it's more tactile than musical <=25Hz.

Final comment - IMO the best sub - mains integration irrespective of sub location, type or quantity should be via an active crossover. Allowing mains to run full range not only taxes the mains' woofers but blurs the bass unless a clean crossover handoff is employed. I say "should" be because I am in process of experimenting with such a configuration and hope it is successful.
 
  • Like
Reactions: Lagonda

LL21

Well-Known Member
Dec 26, 2010
14,411
2,509
1,448
In my opinion "bassiousness" (to borrow Todd Welti's word) is not just a matter of how much subwoofage you have... it's also a matter of how you use it. Here are my thoughts on how to get the most bassiousness out of your subs:

... Absolute Sound reviewer Robert E. Greene tried this when he reviewed my subwoofer system in 2015 and wrote that "Adding a second amplifier to drive two of the four subs separately and thus to be able to adjust their gain and phase independently gives potential for even better results. Dave Griesinger has suggested that putting two subs (or sets of subs) on either side of the listener and running them “in quadrature”—90 degrees out of phase—will produce additional spaciousness, and this seems to work extremely well, enhancing the basic Swarm sound.

"This whole spatial effect is not an easy matter to convey in words. But it is easy to hear, striking indeed, and very satisfying."...

...And in-phase summation is louder than semi-random-phase summation, so the result can be too much very low bass, which can sound fat and slow. One solution is to use the above-described phase quadrature technique so that the summation is effectively semi-random phase all the way down. Another is to reverse the polarity of one of the subs. And another would be EQ....

Thank you again! This gives further food for thought...particularly as I have one main place for subs. The question is whether there is a clever way for me to find two...
 
  • Like
Reactions: Duke LeJeune

Lagonda

VIP/Donor
Feb 3, 2014
3,415
4,670
1,255
Denmark
Great thread and late to the game. What I didn't read or maybe missed was the relationship between subwoofer output to mains bass output. Specifically, you need more and / or larger driver subwoofers to be able to positively affect the frequency response as mains woofer output increases. Positively = flatten peaks and fill troughs across the bass frequencies.

A second point (IME) is that when tuning 2 channel systems' subwoofer integration, sub placement is critical and incrementally so as room volume decreases. A tower of subwoofers will simply not be as strategically advantaged as multi sub placement even if the top subs are higher off the ground. Real - case example - my room has a >10DB ~30Hz peak that after many attempts can only be tamed by subwoofer placement at / near the right rear room entry. The room shape acts as a horn and with proper setup (phase, ELF, xover freq., etc.) it's possible to mostly flatten this peak. It takes multiple subs at and near that location to effectively "manage" this peak. Another room effect is a dip at ~50Hz which again is only flattened by subs at other locations. The sum effect of all 4 subs each in strategic locations yields a house curve while ameliorating major low freq. peaks and dips. Also, I've experimented with 2 - column JLA subs at or near the mains and the 30Hz peak under all placements exacerbates this peak. WRT subwoofer columns I have heard the Rel 6 - pack and I think it yields positive results primarily because it rolls in at ~25Hz, had it been set for anything significantly higher and you'd likely have bass bloat. At those lower frequencies permitting the mains and subs to play both frequencies is tolerable since a) there's little content that low and b) it's more tactile than musical <=25Hz.

Final comment - IMO the best sub - mains integration irrespective of sub location, type or quantity should be via an active crossover. Allowing mains to run full range not only taxes the mains' woofers but blurs the bass unless a clean crossover handoff is employed. I say "should" be because I am in process of experimenting with such a configuration and hope it is successful.
Yes finding that perfect, totally transparent analog crossover is not easy, it always seems to be a trade of. Diminished transparency for improved dynamics and bass control :rolleyes:
 

Duke LeJeune

[Industry Expert]/Member Sponsor
Jul 22, 2013
747
1,200
435
Princeton, Texas
Yes finding that perfect, totally transparent analog crossover is not easy, it always seems to be a trade of. Diminished transparency for improved dynamics and bass control :rolleyes:

I came to pretty much the same conclusion - that tradeoffs are inevitable. So here is an alternative juggling thereof:

If we intend all along to use subs, we can start out with mains designed from the outset to not need a protective highpass filter. This involves the mains having sufficient excursion capability to not distort from unfiltered bass signals up to whatever our SPL target is, and tailoring the inherent bottom-end rolloff of the mains to mate well with the top-end rolloff of the subs.

The tradeoff is that we'd still get more SPL out of our mains with a protective highpass filter, and there is no reduction in the demands on the amplifier.

Another alternative is to design the mains so that they hit our "target response" with the assistance of a simple passive first-order line-level highpass filter consisting of a single capacitor in between preamp and power amp. Because a first-order filter has effect across a fairly broad region, imo this approach calls for the native response of the mains to have a bit of bumpage north of the filter's corner frequency. The advantage of this "hybrid" approach is that it buys us some headroom which we would not otherwise have had, and it reduces demands on the amplifier, though not by as much as a steeper filter would. (In practice these advantages may be offset by needing a midwoofer with a weaker motor and therefore less broadband efficiency to get the aforementioned upper-bass bumpage). It's probably easier to come up with a transparent single uber-quality capacitor than to come up with a comparably transparent analog or digital line-level crossover.

These approaches are arguably feasible if they can push the distortion threshold on the mains high enough that it won't be a factor in normal use. And of course it all goes back to whether or not one buys into the idea that good subs can do a better job in the bottom couple of octaves than good main speakers can.
 
Last edited:
  • Like
Reactions: sbo6 and Lagonda

Lagonda

VIP/Donor
Feb 3, 2014
3,415
4,670
1,255
Denmark
I came to pretty much the same conclusion - that tradeoffs are inevitable. So here is an alternative juggling thereof:

If we intend all along to use subs, we can start out with mains designed from the outset to not need a protective highpass filter. This involves the mains having sufficient excursion capability to not distort from unfiltered bass signals up to whatever our SPL target is, and tailoring the inherent bottom-end rolloff of the mains to mate well with the top-end rolloff of the subs.

The tradeoff is that we'd still get more SPL out of our mains with a protective highpass filter, and there is no reduction in the demands on the amplifier.

Another alternative is to design the mains so that they hit our "target response" with the assistance of a simple passive first-order line-level highpass filter consisting of a single capacitor in between preamp and power amp. Because a first-order filter has effect across a fairly broad region, imo this approach calls for the native response of the mains to have a bit of bumpage north of the filter's corner frequency. The advantage of this "hybrid" approach is that it buys us some headroom which we would not otherwise have had, and it reduces demands on the amplifier, though not by as much as a steeper filter would. (In practice these advantages may be offset by needing a midwoofer with a weaker motor and therefore less broadband efficiency to get the aforementioned upper-bass bumpage). It's probably easier to come up with a transparent single uber-quality capacitor than to come up with a comparably transparent analog or digital line-level crossover.

These approaches are arguably feasible if they can push the distortion threshold on the mains high enough that it won't be a factor in normal use. And of course it all goes back to whether or not one buys into the idea that good subs can do a better job in the bottom couple of octaves than good main speakers can.
My current setup uses the first half of the passive original main speaker filter directly driven from preamp by identical power amp as the sub channels. The sub channels are actively crossed over at the same frequency, 100hz. The second part of the original passive filter, and the original downfiring 12 inch subs are inactive. This gives me the original transparency with added flexibility in the sub region. I have gone trough 4 different crossovers to find the one with the best sound. I did not reinvent anything, i ended up with what MBL are doing in their X-treme model. I just have less midbass capability and more sub drivers.
 

sbo6

VIP/Donor
May 18, 2014
1,659
593
480
Round Rock, TX
Another alternative is to design the mains so that they hit our "target response" with the assistance of a simple passive first-order line-level highpass filter consisting of a single capacitor in between preamp and power amp. Because a first-order filter has effect across a fairly broad region, imo this approach calls for the native response of the mains to have a bit of bumpage north of the filter's corner frequency. The advantage of this "hybrid" approach is that it buys us some headroom which we would not otherwise have had, and it reduces demands on the amplifier, though not by as much as a steeper filter would.

That's the approach I plan to experiment with - a single capacitor along with the amplifier's input impedance yielding an 80Hz high pass filter. Each of the Vivids' drivers cover 2 octaves with the exception of the woofers designed to cover ~3 octaves (220Hz -~30Hz). the first order xover will restrict the woofers' responsibility to ~1.5 octaves while reducing the workload on the bass amp and keeping the impedance > 4 ohms. Additionally this will allow better bass / sub bass management via placement and integration via 4 JLA subs.
 
  • Like
Reactions: Duke LeJeune

ddk

Well-Known Member
May 18, 2013
6,261
4,040
995
Utah
Yes finding that perfect, totally transparent analog crossover is not easy, it always seems to be a trade of. Diminished transparency for improved dynamics and bass control :rolleyes:
If we're talking about just using a lowpass filter/crossover for subs it's quite doable following some basic rules. In the past 10 years I've setup a number of vintage speakers with subs that you wouldn't know they were in the system until you turned them off. Turn them back on and there's no loss of transparency or change of tonality anywhere in the frequency range, there isn't even a wow effect. What you have is a more complete and natural sound with increased 3 dimensionality.

david
 
  • Like
Reactions: Duke LeJeune

Lagonda

VIP/Donor
Feb 3, 2014
3,415
4,670
1,255
Denmark
If we're talking about just using a lowpass filter/crossover for subs it's quite doable following some basic rules. In the past 10 years I've setup a number of vintage speakers with subs that you wouldn't know they were in the system until you turned them off. Turn them back on and there's no loss of transparency or change of tonality anywhere in the frequency range, there isn't even a wow effect. What you have is a more complete and natural sound with increased 3 dimensionality.

david
It’s using active crossovers on the main speakers that always takes some of the transparency, some crossovers do more harm than others, but i prefer only using them in the sub range. I would imagine the carakter could impact the sound if you are using a all tube system.
 

ddk

Well-Known Member
May 18, 2013
6,261
4,040
995
Utah
I came to pretty much the same conclusion - that tradeoffs are inevitable. So here is an alternative juggling thereof:

If we intend all along to use subs, we can start out with mains designed from the outset to not need a protective highpass filter. This involves the mains having sufficient excursion capability to not distort from unfiltered bass signals up to whatever our SPL target is, and tailoring the inherent bottom-end rolloff of the mains to mate well with the top-end rolloff of the subs.

The tradeoff is that we'd still get more SPL out of our mains with a protective highpass filter, and there is no reduction in the demands on the amplifier.

Another alternative is to design the mains so that they hit our "target response" with the assistance of a simple passive first-order line-level highpass filter consisting of a single capacitor in between preamp and power amp. Because a first-order filter has effect across a fairly broad region, imo this approach calls for the native response of the mains to have a bit of bumpage north of the filter's corner frequency. The advantage of this "hybrid" approach is that it buys us some headroom which we would not otherwise have had, and it reduces demands on the amplifier, though not by as much as a steeper filter would. (In practice these advantages may be offset by needing a midwoofer with a weaker motor and therefore less broadband efficiency to get the aforementioned upper-bass bumpage). It's probably easier to come up with a transparent single uber-quality capacitor than to come up with a comparably transparent analog or digital line-level crossover.

These approaches are arguably feasible if they can push the distortion threshold on the mains high enough that it won't be a factor in normal use. And of course it all goes back to whether or not one buys into the idea that good subs can do a better job in the bottom couple of octaves than good main speakers can.
It is possible to add subs and electronic analog crossover without any tradeoffs, it's a marriage and the partners must fit each other well for it to work. You can't just willy nilly put subs and speakers together and think that they'll click.

You know much better than me that the quality of the final product depends on the design and execution Duke, there are no absolutes here. Examples of a successful speaker+sub combo designs are Celestion System 6000 and Soundlab A1+B1 with Apogee Grands and Pipe Dreams for massive fails.

I understand using off the shelf plate amps and digital crossovers in subs built to a price point and using them with similar level products, it's possible to get decent results but I don't get high end manufacturers using the same electronics in subs costing tens of thousands of dollars. These subs will be used with equally expensive speakers some of which are capable of extreme resolution, transparency and accuracy. There's absolutely no way for these subs to blend in with such speakers and not even possible to use them without muddying sound. I've heard many of them including exotics such as Vox Olympians that were completely destroyed by their subs. IME at this level any kind of active sub is a bad idea no less one with digital plate amps and dsp. You MUST have a high quality passive sub to give the user/installer the ability to pick and choose the right electronics to match the main speakers and the rest of the system, you don't have that ability with anything active.

david
 

ddk

Well-Known Member
May 18, 2013
6,261
4,040
995
Utah
It’s using active crossovers on the main speakers that always takes some of the transparency, some crossovers do more harm than others, but i prefer only using them in the sub range. I would imagine the carakter could impact the sound if you are using a all tube system.
I haven't had success using 3rd party electronic crossovers with the main speakers either, including ones that were sold by the speaker manufacturer. I can't tell you if it was my incompetence or the crossover but it always failed.

david
 

LL21

Well-Known Member
Dec 26, 2010
14,411
2,509
1,448
Fascinating...I know Wilson has made a relatively new crossover for their speakers, but I believe a number of big Wilsons owners only use the crossover to control the sub, preferring to leave it running full range.

I will be seeing the Wilson distributor later this month and will ask his opinion as well, as he has set up numerous big Wilsons all over the world...and no doubt with big subs as well.
 

Folsom

VIP/Donor
Oct 25, 2015
6,024
1,490
520
Eastern WA
IME controls for the subwoofer matter the most for integration. Barring any major problems with the subwoofer itself, it's really about having adjustable phase, volume, and Q. Those matter the most, more than the type of amplifier. But I've heard huge improvements in upgrading amplifiers for subwoofers, they were however already integrated.
 

Lagonda

VIP/Donor
Feb 3, 2014
3,415
4,670
1,255
Denmark
IME controls for the subwoofer matter the most for integration. Barring any major problems with the subwoofer itself, it's really about having adjustable phase, volume, and Q. Those matter the most, more than the type of amplifier. But I've heard huge improvements in upgrading amplifiers for subwoofers, they were however already integrated.
It also depends on your crossover frequency at 100hz the differences in class A Krell FPB 700cx on bass and the MBL 9011 on mains was evident, at 50 hz i could live with it. But i clearly prefer crossover at 100hz with identical amps like i have now.
 

LL21

Well-Known Member
Dec 26, 2010
14,411
2,509
1,448
Interesting...presume that at or below 40hz, this trend continues. I believe I have read somewhere that even Wilson Audio has been know to drive the Thors in the Wilson residence with big Parasound amps while the main speaker amps are different?
 
  • Like
Reactions: Lagonda

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