Why is good, deep bass so difficult? - Myths and their Busters


This is a theme that goes round and round and round on Audiogon. While looking for good sources, I found a consultancy (Acoustic Frontiers) offering a book and links:

http://www.acousticfrontiers.com/guide-to-bass-optimization/?utm_source=CTA

Interestingly: AF is in Fairfax, CA, home to Fritz Speakers. I really have to go visit Fairfax!

And a link to two great articles over at sound and vision:

https://www.soundandvision.com/content/schroeder-frequency-show-and-tell-part-1
https://www.soundandvision.com/content/schroeder-frequency-show-and-tell-part-2

Every audiophile who is dissatisfied with the bass in their room should read these free resources.

Let me state unequivocally, deep bass is difficult for the average consumer. Most audiophiles are better off with bass limited speakers, or satellite/subwoofer systems. The former limits the danger you can get into. The latter has the most chance of success IF PROPERLY IMPLEMENTED.

The idea that large drivers/subs are slow is a complete and utter myth. Same for bass reflex. The issue is not the speed of the drivers. The issue is usually that the deeper a speaker goes the more it excites room modes, which the audiophile is then loathe to address.

Anyway, please read away. I look forward to reading comments.
erik_squires
Erik,

+1 on this statement.

"The idea that large drivers/subs are slow is a complete and utter myth. Same for bass reflex. The issue is not the speed of the drivers. The issue is usually that the deeper a speaker goes the more it excites room modes, which the audiophile is then loathe to address."

Kenny.
The issue with deep bass is that it requires sacrifice to implement. Remove every sacrifice, and you are left with two choices:

  • Bass limited systems
  • Muddy sounding, unpleasant bass

And while audiophiles are accustomed to sacrificing in some ways, the ways of deep bass require sacrifices a lot are unable or unwilling to make.

For instance, adding an EQ. Well, you just spend $80,000 on a new dCS DAC stack, you are going to be really unwilling to put a new ADC/DSP/DAC in your chain. This is one good reason for using a sub, so the EQ stays out of the chain of your main speakers.

Bass traps are another sacrifice. It’s not just money, GIK’s Soffit Traps are quite affordable, it is also floor space and WAF. I know of some audipohiles who refuse to do any room tuning at all, but will spend thousands on cables. UGH. Talk about badly balanced priorities!

Then of course there is the amount of time it takes to learn and appreciate the integration a sub requires. It must integrate to the room and the speakers. In addition to finding the best location you are playing speaker designer when you do this, so a background in crossover design is a big help in configuring the EQ and crossover settings. This is a lot of work to develop a skill you will need once.

Alternatives are subs with really good auto-EQ, like JL Audio. Overall too expensive, but really good auto-EQ. When shopping for a subwoofer the most important aspect is the quality of the auto-EQ features. Advice from owners is a big help here, as is an in-store demonstration. HT receivers have this feature as well, with wildly different results.

For all these reasons, I think, an audiophile is right to be trepidatious and maybe even avoid really deep bass. The smaller speaker isn’t faster, it is easier to live with and less likely to bait the dragons that lie in the last 2 octaves. From an overall balance, a limited bass speaker is usually much more room friendly, and therefore, more satisfying to live with.
Erik, I agree that deep bass can be problematic. In my situation, in my large room (16.5' X 34', which includes the kitchen/dining room, w/cathedral ceilings in main living room area). I'm using two subs, a 15" passive Tannoy and 12" Velodyne that I converted into a ported sub with a plate amp and two 3" ports, and Eminence driver (can't remember the model).

I guess you could say I avoided much of the room induced bass problems by using subs that don't go down that deep, not much lower than 30Hz, if that. The two subs are situated katty-corner from each other, the 15" Tannoy next to the L/H Tannoy HPD, the Eminence 14' away.

Due to mostly dumb luck and patience, I was able to integrate these subs into my mostly-music oriented system without exciting any nasty room nodes. My room was very bass-friendly to my 12" Tannoys before the addition of the subs, with the subs, the bass response is nearly perfect to my ears. I do have a modest HT system included in the system, and it sounds great in that mode, but what I've done was all about the music. I hate boomy bass!

There are no room treatments of any kind, nor do I feel the need for them. I consider myself very fortunate indeed.

Best regards,
Dan

Let me state unequivocally, deep bass is difficult for the average consumer. Most audiophiles are better off with bass limited speakers, or satellite/subwoofer systems. The former limits the danger you can get into. The latter has the most chance of success IF PROPERLY IMPLEMENTED.
I couldn’t agree more. I made that mistake, of going for a big speaker as my first foray into this madness and it simply overloaded my room. The speakers were Legacy Classics. Having gone through several other speakers I’ve found the goldilocks speaker for my room: a monitor. I have no need for a sub as I get very tangible bass down to the mid 30s with the low 30s and upper 20s reasonably represented.

It’s tight, tuneful and full of tone, and very well delineated. The only downside is that they’re rear ported so there’s that secondary piling on at certain frequencies but it’s easily tolerable and maybe I’ll look into something else to quell it but it’s not a deal breaker, in the least. Others don’t notice it until I point it out.

All the best,
Nonoise
ULF Bass is the most difficult to reproduce accurately. 99% of what is available is reflex extended resonant bass - B&W, Wilson, JM Labs and all the major audiophile brands do it. Most boutique brands do it too. You can easily identify this by the hump in the bass on a frequency plot and the one note bass sound of 99% of speakers.

Clean bass needs a Q of 0.7 or less and two 15 inch woofers in most domestic settings. (4 x 12" woofers will be equivalently capable.) I rarely see this kind of setup on Audiogon so I don’t think many people are even aware of the issues raised by Erik.

Sticking a good subwoofer with 99% of these reflex extended speakers is just not going to be able to correct the one note resonance. Hardly anyone builds speakers without the characteristic one note bass resonance as a low Q box sounds anemic in bass especially at low volumes and is therefire unlikely to sell in shop floor demos against competitors.
aha!  room modes

yes, we are back to rooms again - maybe we can find some magical liquid cables that will solve that???
see also Fig. 11-21 in Handbook of Acoustics...
Post removed 
http://www.eminent-tech.com/main.html

Click on TRW-17 pic. Looks like a fan. Then "output comparison".

Dave


@kost_amojan. 
 
Well it should be easy for you to show me a link to a Stereophile or other measurement plot of a JM Labs high end speaker that does not have a bass boost, bass bump or hump?

You should be looking for a flat response that gently rolls off in the bass with no increase in response below 120 Hz at all. I feel sure you can find this as you are extremely confident.
I have seen a couple of takes on the fan as a woofer idea.

Just FYI, as Dr. Leach was fond of saying, 0 Hz isn’t a sound, it is wind.

Another was kind of a corkscrew in a tube. Seems to be long disontinued, the Phoenix Gold Cyclone by BNIB.

Another way to use a rotating motor is converting the rotation to linear travel with a flapper, like the Devialet.

Neither method really resolves room mode issues and trades motor strength for effective surface area. As a signal drops an octave, displacement must increase by a factor of 10 for any given driver, so 1mm at 40 Hz becomes 10mm at 20 Hz, and so on.

Fans, assuming they can spin fast enough, eliminate the excursion issue. No idea about distortion figures. I can say that with a Hsu VTF 15 I can get monstrous output in room at 16 Hz, so not really a problem I need to solve.
Did a little searching on data-Bass.com

At least on paper, the rotary woofers don't seem to do all that great compared to far less expensive solutions. Seem to be just as output and distortion limited as their coned counterparts, or at least close enough to make the $12k price tag questionable.

Best,

E
@erik_squires

I haven’t read the articles in your initial post as you state "every audiophile who is dissatisfied with the bass in their room should read these free resources’ and I am not dissatisfied.

Give a serious listen to a pair of Golden Ear Triton Reference and I think you would conclude that good, deep bass is *not* so difficult.
gdhal,

We are not going to agree there, at all.

Best,

E

I went through this bass problem and solution this year. I did investigate some. The DBA double-bass array did seem to solve a lot of the problems, but I just could not implement that many drivers in my room. Based on my experiences, there are actually a couple things that are required for good deep bass:

- Power supply in source/preamp (and even amp) components.

- Acoustics / standing waves problems.

The power supply capability in source/DAC will absolutely contribute to deep/tight/strong bass. The dac/preamp may sound good, but unless it has a massively sized power supply, it will just not be able to push those very large waveforms. I have seen discrete Class A preamps that the manufacturer has just tossed a couple 3200uf caps in and called it a day. A good example is Krell KAV-280p and Bryston BDA-2. Both have undersized power supplies, in my opinion. You really need something like 20,000uf for Class A circuits. The Oppo BDP-105 has a decent power supply (2 x 6800uf), but remember it is using conventional op amps (not Class A). This is not the whole story however. Avoid gold-plated or silver-plated components if you want deep/tight/strong bass. This is where rhodium plated elements can be your friend (power cords, interconnects, even fuses when applied conservatively and properly).

The other problem is, of course, problems with standing waves in small rooms. I went through a bass tuning exercise this year and I actually now have 14 (counted them) 2’ x 4’ bass panels. Six Owens 2" 703FRK, four 2" Roxul Rockboard 80, two GIK Monster Bass Traps with Flexrange Limiter, and two limp-mass bass panels tuned to 63 hz. All are covered with Guilford fabric except for the limp mass. I plan to add two more limp-bass bass panels tuned to 50Hz.

The bass is significantly (night and day) deeper and stronger that it was before at my listening position. I also no longer feel like my ears are compressed in a vacuum (due to over pressure at some frequencies). It is a enormously better situation. I made all bass panels myself except for the GIK. I think I spent less than $1200 total.

Acoustics is very important here. However, if the deep/tight bass is not there from the source/preamp, you are not going to get it by adding bass treatments.

I will say that the GIK monster bass trap with the FlexRange limiter is an exceptional product if you are looking for a broad-band bass trap. The limiter panel increases bass absorption without sucking the life out of the mid/high frequencies. Positioning is important as this may work better in some areas.

Erik,

I suggest you call Bruce Thigpen @ Eminent Technology and tell him about the article you read or even Albert Porter who has heard the TRW-17. Be brave.

Dave
11 band analog EQ tunable for the listening sweet spot :-)
an additional subwoofer if needed for ego or rooms with small hands
push pull aluminum cone driver
decent plots over time
pistonic motion verified with a special laser system so that we know what the cone is really doing...knowing is the key to the scientific method
disc or download 11 band signals, SPL meter to set EQ
power factor corrected monoblock sub amp built into box
stealth enclosure with autoclave bonded low resonant cabinet
adjustable Q
owner answers the phone, calls me during fishing season to make sure I am still alive...

same basic technology available in the line for < $ 15 K

i am happy
oh and a high pass phase correct filter so you higher frequency amp dont have to work that hard....
oh and here is an almost free tip
download vandertones
get the analog Radio Shack SPL meter...put meter at listening height at listening position, record what your speakers and the room are doing

use the Vandersteen math based ( there is that damm science stuff again ) to consider placement changes...just download a Vandy manual for free and get out your tape measure...
I can be quite brave when I say I could not justify $12k on a subwoofer. :)

Your wallet may be less prone to pain and suffering than mine however, and I welcome you to spend as much as you'd like.

I will say that I have plenty of output and my HT has as much output at 16Hz as I want or need. My previous apartment was even better sounding than this one, but I'll survive.

Best,

E


Nah its not difficult - just requires some room :-)

http://pbnaudio.com/speakers/montana-speakers/master-reference-loudspeakers


Good Listening

Peter
For measurements, if I'm not using OmniMic, the Android app AudioTools + the Dayton IMM6 microphone is a real godsend.

Best,

E
For not a ton of money you can get the Behringer ultracurve and measurement mic.   Then you can put the ultracurve between a digital source and DAC.  This will give you all the digital equalization you could ever want. 

It also allows you to compare the digital signal from the source with the analog signal coming from the measurement mic.  Get a tone generator and you can see the difference at every frequency.  I did this many years back and it really helped me understand how the room, bass traps and equalization effect the sound.  

If you aren't willing to do this or similar and you are bothered by uneven bass then I agree that it's best to have a system that doesn't do deep bass.  

https://www.amazon.com/Behringer-DEQ2496-BEHRINGER-ULTRACURVE-PRO/dp/B000CCN152


Hi Erik,

Roger on the cost. Plus having to build the chamber.

Sounds like you get a lot of low bass. Do those woofers also load the room?

Dave 
Dave, I'm now in a completely open floorplan, so no room loading. Previously, yes!

Rather than the Behringer, I like the miniDSP line. Easier to control via windows UI, and I can feed it directly from OmniMic. I measure the response and then have OmniMic calculate a correction curve, and I'm done.

What I like about OmniMic is my ability to tailor the target curve. I usually go for a 1 to 2 dB/octave descending slope starting at 16-20 Hz for the sub. JL does a similar thing.
This thread is a bass fishing tournament.
Don’t fear a creative solution.
1. Try decoupling your subs from the floor beneath them.

2. Mass load the subwoofer.

3. Use a sub with an adjustable "Q"

If you are listening in a square box (literally), good luck!
Extension is only part of the sound and you don't need a lot of extension to listen to acoustic bass or bass guitar (lowest note 41.2Hz).  My current speakers, with larger woofers, have worse (by 5Hz) extension than previous speakers but bass sounds much better.  It is not extension or dynamics, but just sound of the bass (both bass reflex).  Attack and decay of the note sounds right (natural).  I also suspect that distortion is lower (woofers without spider-web suspension, larger volume).  

Previous speakers had 2 1/2 way xover meaning that one woofer covers bass and midrange while the other supports low bass.  That way it is possible to stretch extension from small woofers in smaller cabinets but it won't sound as good as larger woofer.

Most of the woofers have overhung motor construction that produces more distortions while only few manufacturers (Including Acoustic Zen) use underhung motor, perhaps because it requires much larger magnets.

I hate to judge before all the facts are in but it appears a big advantage of headphones is you can get very good bass performance without all the angst, effort and cost oft required to obtain very good bass performance for speaker systems. And that's if you're lucky and don't actually make matters worse.

Clean bass needs a Q of 0.7 or less and two 15 inch woofers in most domestic settings. (4 x 12" woofers will be equivalently capable.) I rarely see this kind of setup on Audiogon so I don’t think many people are even aware of the issues raised by Erik.
The Classic Audio Loudspeakers that I have (model T-3.3) use dual 15" drivers, one forward firing and one down firing. The model T-1 employs a 15" forward firing and an 18" down firing. Both cut off at about 20Hz and are 98db 1 watt/1 meter. I regard the bass as very musical- its is very nuanced and has plenty of wallop.

A subwoofer system that solves many bass/room issues is the Swarm by Audiokinesis. It employs mulitple small subs and so effectively reduces room nodes, standing waves and the like.
Geoffkait is right…you can also get most of the joy of driving high performance cars from video games, and great food is available by simply looking at photos of it. It's not necessary to go outside to experience nature when high def TV has it all right there! I make the mistake of working with live musicians frequently when really, I should stay home festooned with my Grados and avoid crowds and pesky personal hygiene. I actually asked Jim Campilongo if he's tried reversing the fuse direction in his Princeton Reverb…no answer…at least he didn't take a swing at me.
"Upon graduation from Acme Audio Engineering school today many of you will go on to do great things. The rest of you will be in pro audio."

omg Wolf that is funny
when nobody is looking i will flip the fuse on the church organ
......which sounds quite lovely run into those two little ribbons into my high speed B77

i actually know what 16 HZ sounds and feels like....on Sundays
Over the years I've had multiple setups with subs.  Sometimes they are very frustrating to get integrated, so the system doesn't sound like it has sub woofers, this last time was the most frustrating, as the room had terrible acoustics in the bass region (the room added a single bass note, no matter what the bass player was playing).  It took a LOT of patience and time, a calibration microphone and the REW software to help me place 10 bass traps, but when I finally got the subs "dialed in", I'm in "bass heaven"!
Oh, I have a pair of JL Audio F113V2 subs, augmenting a pair of Focal Sopra No2's.
For accurate information on the Eminent Technology TRW-17 Rotary Subwoofer, read Peter Moncrieff’s IAR review of this revolutionary (no pun intended ;-) product.

Designing and building a woofer system that is theoretically flat to a very low frequency is not that difficult, but it is of academic interest only once that woofer system is placed in a room: At low frequencies, the room’s effects are totally dominant.

There is usually a LOT of room for improvement at low frequencies. Equal-loudness curves predict that the ear is especially sensitive to differences in SPL (peaks and dips) at low frequencies. A 5 dB change at 40 Hz sounds like a doubling of loudness, the same as a 10 dB change at 1 kHz. (This also explains why it takes so long to fine-tune the level control on a subwoofer system - a small change in SPL makes a disproportionate change in perceived loudness.)  Therefore, smoothing the in-room bass makes a greater subjective improvement than we would have expected from eyeballing the before-and-after curves. 

We all want "fast" bass, but what is often not appreciated is that "smooth bass" IS "fast bass". Literally. Because speaker + room = a linear phase system at low frequencies, the time-domain response and frequency response track one another. Fix one, and you have fixed the other. Because room effects are dominant at low frequencies, the most direct path to "fast" bass includes addressing those room effects.

The precise details of the room’s effects differ from room to room, but the basic issue of room-induced, large, highly audible peaks-and-dips is pretty much universal, and there are similarly universal solutions. Remember this is an acoustic problem, so it is most efficiently addressed with an acoustic solution.

One way to get smooth in-room bass is the distributed multi-sub system. Inevitably, each of the subs generates a unique in-room peak-and-dip pattern (and this is true for any listening location within the room). BUT the SUM of these dissimilar peak-and-dip patterns is significantly smoother than any one of them on its own.

An example of a non-acoustic solution would be equalization. When we fix the response of a single subwoofer at a single listening position with EQ, we are (almost inevitably) making the response worse somewhere else. And as we widen the area where we want to make an improvement with EQ, we reduce the amount of improvement that can be made. Distributed multisubs + EQ can work REALLY well, because the multiple subs significantly reduce the spatial variation in frequency response (in addition to making the frequency response significantly smoother), such that if we still need EQ, chances are it will be addressing a global (room-wide) problem, rather than a local one, so it will not be making the response worse elsewhere in the room.

In my experience - which admittedly includes a disproportionate amount of work with distributed multisub systems - a good distributed multisub setup is more effective from a sound quality standpoint than EQ or room treatment alone... though of course the use of one does not preclude the use of the others. Deepest loudest bass for the dollar comes from using a single equalized ubersub, but quantity without quality becomes fatiguing over time.

There are quite a few different ways to implement a distributed multisub system. The main points are, use enough subs (small ones are fine) and get ’em spread out.

Imo, ime, ymmv, etc.

Duke (yeah I got a dog in the fight... four small ones, actually...)

Yes, buy a measurement mic

but even before that buy or borrow a copy of the Master Handbook of acoustics and learn a little about the physics - it will cut the time spent with the measurement mic by a lot

3rd... room tmts.

4th - bigger speakers or subs - a multi-sub setup can be very effective

and.. as per a post above - Get The Mid-range Right before anything else

geoffkait wrote: "I hate to judge before all the facts are in but it appears a big advantage of headphones is you can get very good bass performance without all the angst, effort and cost oft required to obtain very good bass performance for speaker systems. And that’s if you’re lucky and don’t actually make matters worse."

Headphones are a lot of fun, but they are not good for accurate bass reproduction. This is at least in part because a) we perceive bass, and in particular deep bass and impact, with our whole bodies - not just our ears; and 2) there is no room reverberation tail on the notes, and room reverberation done right improves our ability to perceive pitch accurately, plus room reverberation is a component of perceived loudness (sounds that last a little bit longer are perceived as being louder).

If headphones were good for bass, they would dominate in the recording industry. Mixing and mastering would be done on headphones. Instead mixing is usually done on small nearfield monitors, and mastering on big main monitors, and if headphones are used at all, they are never relied on to tell the truth in the bass region. Some beginners hope to rely on headphones for mixing in their "budget" home studios, and you can find and follow their painful learning curves on prosound forums... you know, where those other Acme graduates end up...

Duke

One way to get smooth in-room bass is the distributed multi-sub system. Inevitably, each of the subs generates a unique in-room peak-and-dip pattern (and this is true for any listening location within the room). BUT the SUM of these dissimilar peak-and-dip patterns is significantly smoother than any one of them on its own.

This is one reason I have a *pair* of Golden Ear Triton Reference. Each one on its own eliminates the need for a sub, but the two of them (subs) combined sounds even better.


audiokinesis, thanks for the Acme Audio Engineering School lecture. Looks like this is going to be one of those he said, she said things.  😀

"This is one reason I have a *pair* of Golden Ear Triton Reference. Each one on its own eliminates the need for a sub, let alone the two of them combined." - gdhal

Yup, when it comes to using multiple bass sources in the pursuit of in-room smoothness, the more the merrier.

In general, with intelligently distributed multiple subs (and there are different distribution strategies), the in-room bass roughness is approximately cut in half for every doubling of the number of subs. So two subs are potentially twice as smooth as one, and four subs are potentially twice as smooth as two... and eight subs are grounds for divorce in most states.

"audiokinesis, thanks for the Acme Audio Engineering School lecture." - geoffkait.

I flunked the Acme Laws of Physics class... which teaches that gravity doesn’t start working until you look down...

http://commentphotos.com/gallery/CommentPhotos.com_1407347817.jpg

Duke

good room ratios, enough volume, lots of bass traps, nice powerfull amp and strong stereo subwoofers make for clean deep bass without spending 20k on cables or whatever else...

i also got the Mytek Brooklyn and honestly its pretty extended in the low end really clean also, and no compromise on the rest of the spectrum its driving a Mcintosh252 with Eggelstonsworks Rosa and two Velodynes Spl12, with a large back wall full of basstrap and each corners of the room treated as well, my room is rather small and the results are quite amazing. all bought second hand except the Mytek, I use also a Grace M903 from time to time with similar low end but different top end (slightly harder)

I call that hi end audiophile on a budget!

I couldn't get the bass right without the proper amount of bass trapping no matter the ratio of the room .

Gentlemen,

I  agree whole heartedly with Duke's comments from Audiokinesis and would like to point out if you don't want to do room treatment and have the budget you should try out the Lyngdorf TDAI 2170 with Room Perfect ($4000 to $5000 depending on options). This includes a world class DAC and electronic crossover network at the base price.
Now I admit I am a dealer for Lyngdorf and will financially benefit if you purchase one from me, of course, the upside to you will be the best possible sound your system can provide, It is easy to use and when you are old and feeble you will still be able to pick it up and move it.
I do have some lucky customers with Duke's swarm and the Lyngdorf and they are perhaps the happiest of all. Smooth bass as low as it can go.

Neal Van Berg
www.soundsciencecat.com




I didn't read this entire thread. If this point has been made, then consider this a +1.

A long time ago I did a lot of reading. One of my favorite sites was www.humblehomemadehifi.com . Tony G said it plainly, and often; for tight impactful bass, you must use a cored low Rdc inductor. 

I use the Mundorf Zero Ohm types.

Why don't manufacturers use them? They're anywhere from $200.00 to $500.00 each (depending of size). Since we need one in each speaker, this means $400.00 to $1,000.00 just for the inductors. Are you kidding me. These dollar values constitute the entire crossover cost, if not less.

If you own a 3-way or a 4-way, take the leap. Open up the speaker, get the large inductor value, and order them. Yes the lower resistance will shift the crossover slightly, but the gains will be huge.
Without bass eq, unless you are in a anechoic chamber, the bass notes will smear the other bass notes, and coherency is impossible, which is essential to good, clean, deep bass.  
This has been an incredibly informative thread. I have a small listening area and use monitors and while I don't have _too_ many bass issues, i do have a node somewhere around 50-60hz. For some practical reasons, I would like a floor stander in my room. Have any of you used sealed speakers - something like magico comes to mind. I am not asking for speaker recs/reviews and don't want to derail this thread...My question is simply, do sealed speakers integrate better into these rooms? Wish I could do an in-home demo to test but that's not an option currently.
I agree with audiokinesis.  I have used Thiel 3.5's for years, which with their equalizer are flat down to 16-20hz.  The ultimate bass system: 4 or 5 of these in an ITU multichannel configuration.  Virtually all room nodes are eliminated.  Two of them in stereo, because Jim Thiel designed them for optimum sound in a very room-friendly design, can generally be positioned in a room to minimize their room-node response and at the same time, excellent stereo soundstaging..

Equally important, study the basics of sound physics so you know what you are doing/looking for, and if in a general living area, use furniture, curtains, bookshelves, etc to serve as sound modifiers and even psuedo-bass traps.  Good smooth bass can be done, but not in ignorance.  It requires knowledge and experimentation and a willingness to find the proper speaker locations and then design the remainder of the room layout around that.
I have always found that a very important part of good bass response is the damping factor of the amp, the ability of the amp to control the excursion of the bass driver.  I've had some pretty expensive equipment over time where the mids and highs were fantastic but the bottom end was lacking.  In most all cases the damping factor was low.  I also learned that I more enjoy a smaller sub in a sealed box (as opposed to ported), especially since I gravitate toward planars and other very fast response speakers.
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