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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
bdp24's avatar
bdp24
9,805 posts
 

The Rythmik Direct Servo Feedback Subwoofer system is a very sophisticated design (patented, for what that’s worth)---many subs are nothing more than a woofer and an amplifier in a box---that accomplishes a number of goals for it’s designer, PHD Brian Ding. For instance, all loudspeaker driver voice coils heat up with use, slightly altering the driver’s electrical characteristics. The Rythmik DSF compensates for changing woofer coil temperature, keeping the driver’s electrical characteristics consistent. All woofers, in fact all drivers, would benefit from that.

All drivers have a rise time (when hit with a signal), and a return to "rest" capability (when the signal stops), ideally not over-shooting the "at rest" position of the voice coil within the magnetic field of the driver’s motor when attempting to do so. Servo-feedback systems, found in the woofer columns of the Infinity IRS and RS-1b (which I use to own), have long been known for affording superior inter-transient silence, another term for non-overshoot driver performance. There are a few ways to achieve high performance in that regard, servo-feedback being a cost-efficient means of doing so. The Rythmik subs excel at that performance characteristic. Just as the Eminent Technology LFT driver has been described as "quiet" (very low "noise"), the Rythmik subs have a very high degree of inter-transient silence. They are unusually good at blending with planar loudspeakers, sounding "leaner" (no bloat) than most other subwoofers.

The Rythmik sub designed in collaboration with GR Research’s Danny Richie, the only OB/Dipole sub in the world featuring servo-feedback woofers, is State-Of-The-Art. A pair of those subs (usable up to 300Hz), combined with the Eminent Technology TRW-17 Rotary Subwoofer (designed to be used for reproducing 20Hz and below!), greatly exceeds the capabilities of any other subwoofer in existence. Not cheap (the TRW-17 especially), but cheaper than the woofer section of the $100,000 and above loudspeakers available to the well-heeled.

Rythmik owner/designer Brian Ding has a very detained explanation of his designs on the company website, for anyone interested enough to read it all. Warning---it’s quite technical!

wolf_garcia
6,696 posts
 
I think there is a lot of pretentious blather around this subject…any good main speakers in a normal room (furniture, books, things people simply own) should sound great if pointed at you properly, which requires some moving of the things away from walls, toward walls, wider apart, closer…until YOU think it's sounding good. Then get a sub or two (I use a pair of "previously owned" "Q Series" RELs), move 'em around until they seem to sound good, and relax. Done. If you think you think you need DSP then add that, although I don't like it. A friend uses the same main speakers I have (Silverline Prelude "D'Appolito" arrayed small woofer things) with 2 RELs like mine, and the DSP simply seems to strangle the sound somehow, so I remain without EQ of any sort, other than sub level tweaking here and there.
shadorne's avatar
Ag insider logo xs@2x
shadorne
7,477 posts
 
@bdp24   

I believe Meyer do this also (a microphone in front of the woofer).

The alternative to correcting for errors is to eliminate them by using a single layer large 4" short length voice coil in extremely tight tolerance massive long magnetic gap - very expensive woofers indeed!
johnk's avatar
johnk
1,975 posts
 
Schrodinger didn't microwave a cat. He came up with a thought experiment Schrödinger's cat about the bizarre nature of quantum superposition's. To me one making such a wrong comment in a technical article shows incompetence of author. 
geoffkait's avatar
geoffkait
23,365 posts
 
johnk
Schrodinger didn't microwave a cat. He came up with a thought experiment Schrödinger's cat about the bizarre nature of quantum superposition's. To me one making such a wrong comment in a technical article shows incompetence of author.

I trust he was attempting a little audio in light of the fact microwaves had not yet been invented in 1935. Maybe the author would have been well advised to write, Schrodinger was the dude who shot the cat, or poisoned the cat or smothered the cat. Say, how could the cat live inside the box with no air? 
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