Slow bass myths encouraged

[johninCR]

Pinkmouse,

I notice that you didn't say that the sub with many small drivers sounded bad.

The reason you prefer pro sound drivers to typical high Le high excursion sub drivers is that they don't sound as "slow". I consider it a valid and easy way to avoid the mushy slow sound of typical subs and multiple small drivers is another easy method. You do however run into similar hurdles to overcome in terms of output and extension on the bottom end.

Paul,

I'm sorry but "slow" and "mushy" are much more descriptive and you know exactly what I mean when I use them. In the list of "more appropriate technical" terms, the only one that comes close is transient response but I believe that encompasses much more than just what occurs below 100hz. Of course, you're just looking for something to argue about anyway.

The fact of the matter is that you can take a bunch of cheap little TV drivers and make much better bass than you can with a typical high excursion subwoofer driver and have money to spare.

[Tweeker]

I made the dig on the pr not so much because theres anything wrong with them, but because in this cases its whats making alot of the real LF response, and well, its 10 inches and not tiny. This is internally inconsistent with thier marketing line of BS. And in one interpretation of "speed" a pr has more group delay than would an active sealed woofer.

[DSP_Geek]

And the magazine quote claims "great results from 1-100Hz". Seeing as how a PR enclosure is at least 4th order, dare we imagine a corner frequency somewhere around 2 Hz or less? *snort*

I can just see a quartet of 5" drivers struggling valiantly to push the 15 Hz component of the "Apollo 13" liftoff - even with a PR in the box the viewer'd probably be using voice coil for dental floss after booster ignition.


In a more serious vein, "slow bass" to me seems correlated with flat response followed by a sharp rolloff, which with room gain tends to leave a peak right around the corner frequency (draw the graphs and see), which I suspect is why Linkwitz has a switchable 1st order 50 Hz highpass in the Orion crossover. Vented boxes can mitigate that by using alignments which roll off earlier and less steeply, such as Bessel, instead of Butterworth or Chebyshev. Wilson speakers take that approach, and most people describe them as "fast" even though they use 8", 12" or (heaven forfend!) 15 inch woofers.


Francois.

[johninCR]

Tweeker,

I agree the sub that started this thread is probably a piece of crap like most storebought subs. Using the small drivers it is likely to sound better in the 50-100hz range than most of the stuff they pawn off on the public as subs. They took what I consider a valid point about using multiple small drivers and twisted it to suit their marketing strategy. It's very possible that some accountant told them the 4 smaller drivers would be cheaper than one larger driver and the marketing department is using that as a way to differentiate their product from the other stuff out there and charge extra.

[Dave Jones]

JohninCR, you're not only wrong, you're loud wong.

[johninCR]

Originally posted by Dave Jones
JohninCR, you're not only wrong, you're loud wong.

That's the kind of response I'd expect from someone who thinks bass using a pr alignment is the cats meow.

Your little blurb WRT what Klipsch claims is just more justification to use lots of small drivers, more surface area, less excursion. While using ported or pr alignments may help reduce IM distortion, they do plenty to mess up the sound in other ways. If you can't hear the difference, that's your problem.

WRT to references to Fast or Slow bass, they are subjective references to what the bass sounds like, not the velocity of the driver cone. You and Paul already proved that the high excursion drivers have to move their cone with greater velocity. Throw on top of that the high Le which makes those types of drivers slower to get going to begin with and what you end up with is "slow" sounding bass.

[mike.e]

Can the people referring to high Le slow bass please refer me to some facts not fiction - AES or similar -Im yet to see a real reason to convert to low Le subwoofer drivers.

Cheers

Pinkmouse,

I notice that you didn't say that the sub with many small drivers sounded bad.

The reason you prefer pro sound drivers to typical high Le high excursion sub drivers is that they don't sound as "slow".

Are you sure you know HIS reason for enjoying the prosound woofer sound? its probably more along the lines of flux shorting rings and lack of <20hz output making people think its faster bass.

[johninCR]

Check out the texts that Dan Wiggins did in Adire's technical papers. Added mass to the cone didn't slow down the impulse time of the driver, but added Le did.

[paulspencer]

I'm prepared to accept the use of the term "slow bass" as long as we keep it purely subjective. I think part of the problem here is that those who use that term often don't stop there, but venture into theory that seems a bit shakey and lacking any firm foundation. It's one thing to make observations and subjective descriptions, but it's another altogether to match what we hear with a technical reason. Let's be honest, we mostly amateurs here, some of us have designed speakers, most of use have heard a lot of systems, some of us can measure speakers but few of us have the means to really conduct research here, the kind that can back up claims adequately of what really is the technical reason behind the perception of "slow bass." Most of us form theory to try to make sense of what we have heard.

There are statements here that seem plausible, but I don't see enough evidence here to pin down conclusively what fast/slow bass means technically.

* small woofers are faster

I think if you really want to prove that you want to do some serious research, try to eliminate the differences that can skew perception - it may be that they are only "faster" since they have less bass down low, it might be related to rolloff, it might be transient response, it might be distortion/linearity issues, it might relate to the nature of the cone itself or features of the motor design ....

* higher inductance means better transient response and faster bass

I'm familiar with this article on Adire's website, and they make a good point regarding the inductance impact on the timing of the peaks in an impulse response test. What is not clear is how this actually relates to perception. A study would be needed to determine this with a decent sample and blind listening tests. I suppose if anyone wanted, they could in fact try this out, adding inductance to one of two identical woofers, then using eq to get the same frequency response. They could do blind AB listening tests with a group for 1) standard 2) inductance added 3) frequency response compensated with eq.

I have heard a vented tumult subwoofer that I would describe as very fast. It was calibrated along with 4 other subwoofers to be flat inroom. The Tumult despite its XBL2 design has a high inductance, and that along with the vented box would in the opinion of many, lead to slow bass, but it was certainly not that.

Again, I suggest that we don't really understand fully what produces "fast bass" from a technical point of view. Depending on how I set up my subwoofers, which have lower inductance and are currently in sealed boxes, I can get them easily to sound slower, from what I recall.

So what does this fast bass really mean in technical terms?

I don't know ... I'd like to see someone demonstrate it with credible research, but I'm not sure it will happen. If someone could really prove it, it would be interesting to see if it would change the industry. I have a feeling marketing is a stronger force than research, as the former often feeds on misinformation, being perception based.

But I'll take a stab at what might be involved:

* room modes

I think this is a biggie. My room has a massive peak around 35 - 40 Hz depending on placement and then a dip around 80 Hz. When a sub is placed in the room uncalibrated, that mode creates an exaggerated character to the bass, which for a while I liked, especially on movies since a lot of the potent LFE are around there. If you have small monitors rolling off below 50 or 60 Hz then most likely you avoid room gain and modes which is possibly one of the biggest causes of "slow bass."

* group delay

already suggested, but inconclusive. As you get lower down, it gets harder to keep GD low. A rumble filter increases GD below 40 Hz to crazy high levels. If GD really is a big factor, then this points things in favour of sealed subs, which don't rely on a rumble filter as much, but also have much lower GD, so after a rumble filter is used, they don't look too bad.

* transient response

I'm a little undecided on this one ...

* integration

I've heard the suggestion that "fast bass" relates to having higher frequency content coming from the subwoofer. If the sub level is set louder, or there is a gap in between the sub and mains, they will not integrate well, and the deeper bass will be disconnected from the upper bass and lower midrange, which may in fact be the critical region in giving the impression of "fast bass."

* distortion

as you get lower you have more excursion and higher distortion

[mike.e]

Check out the texts that Dan Wiggins did in Adire's technical papers. Added mass to the cone didn't slow down the impulse time of the driver, but added Le did.

Ofcourse i saw those years ago. The issue is,is the discrepancy audible! thats what no one will answer me.