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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_squires OP
16,056 posts
 
Hi @cousinbillyl

Slightly different topic. That is about perceived impact and multi-way speaker design with passive filters. Impact is not actually deep bass. That’s just regular bass. :)

A powered subwoofer would skip the inductor/filter issue altogether.

Not the first time I have read this statement, so there may be some truth to that, but there are a couple of myths too. Good cored inductors with very low DC start rather inexpensively. The issue with designing a low pass filter is more complicated than merely reducing the DCR. No one should start replacing coils willy-nilly. There are a number of issues that can be introduced by doing so.

Best,

E
erik_squires OP
16,056 posts
 
gkr:

The amps and speaker matching are certainly a factor. I remember the first time I really heard a difference in amps was watching the dealer swap in a Tandberg to play Snell A/IIIs.

Remarkable power, smoothness and extension. I was quite enamored. The "trick" to the Snell's bass was woofers with significant amounts of added mass however, so it is unlikely these drivers have survived up until now.

I recently owned a Tandberg amp again, though, and have to concur with the original reviews which called them grainy on the mid/treble. << sigh >>

harry:

Very few speaker designers really appreciate the value of designing speakers for a room / location instead of quasi-anechoic. That's how I design mine and it's a huge help.

Best,

E
mains
170 posts
 
For great bass you must isolate your speakers from there environment, remove the spikes and replace with Townshend Audio Seismic Podiums or Seismic Speaker Bars, your speakers will then be free from any boom or distortion which will allow you to hear/fill your speakers best bass performance plus the rest of the frequency’s become much clearer open and natural
please check Max Townshend you tube video Spikes v Podiums
I use Podiums with my Sound labs Dynatats my bass is awesome, the hole sound has improved good luck but great bass is very possible once you have isolated your speakers from there environment. 




audiokinesis
2,737 posts
 

Skanda wrote: "Do sealed speakers integrate better into these rooms?"

It’s ALWAYS a matter of speaker + room, and if the room is contributing a lot of boundary reinforcement, sealed boxes generally result in better synergy. If not, then vented boxes generally result in better synergy. I can go into more detail if you’d like, BUT the specifics ALWAYS matter more than these sort of generalities.

* * * *

A lot of different suggestions have come up in this thread, things that have obviously worked for the people who tried them. Because of the ear’s exaggerated sensitivity to small changes in SPL at low frequencies (shown by the bunching up of equal-loudness curves south of 100 Hz), combined with its poor time-domain resolution (which is why we can’t localize the source of very low frequency sine waves), we can infer that the improvements we hear are primarily due to changes in SPL, even if they "sound like" changes in "speed".

At the risk of over-simplifying, and being open to correction on any of these points, some things simply make a bigger difference than others. To set the stage, it’s not uncommon for in-room response across the bass region to have peak-to-dip swings of ballpark 12 dB, or +/- 6 dB. Changes to speaker damping (mechanical or electrical or acoustics) seldom result in more than a 1 dB difference, but in the low bass region that's as audible as a 2 dB change in the mids. Improvements to room acoustic damping (bass trapping) can result in 2 dB or maybe 3 dB reduction of the maximum peak-to-dip swings. EQ is generally good at chopping off the peaks but not so good at filling deep dips, still +/- 3 dB is often feasible, and perhaps better if optimized for a small sweet spot. A distributed multisub system results in smaller and more numerous peaks and dips (which has psychoacoustic benefit), with +/- 3 dB over a wide listening area being reported by many users. Remember, smooth bass = "fast" bass, perceptually.

The good news is, these different approaches are not mutually exclusive. You can start with one and then add another as your piggy bank recovers.

One final implication of the bunching up of the equal-loudness curves south of 100 Hz is, there is subjectively a LOT of room for improvement over the typically poor low frequency response of most speaker/room combinations.

Imo, ime, ymmv, etc.

Duke

don_c55
1,025 posts
 
Pay attention to slap echo and standing waves.

Use acoustic suspension not bass reflex.

Use a simple butterworth low pass crossover.

Use two subwoofers. 
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