fEARful for Dummies

[BlueTalon]

I'm starting this thread because of my own desire to understand the topic better. Hopefully, it will serve people other than just myself. The purpose of this thread is to be the place where I (and others) can ask the basic questions about fEARful stuff without impeding the more advanced discussions (rants, diatribes, whatever) going on elsewhere.

I'm lifting these quotes from another thread:

Originally Posted by BlueTalon

I spent almost 20 years in the military. I've learned how to use explosives, speak Russian, and work on gas turbine engines. I have two bachelors degrees. I am not stupid. But I am completely freakin' lost in this discussion.

I only just heard about fEARful a couple weeks ago here on TalkBass. I am interested in fEARful cabinets. The people that have them rave about them, pretty consistently it seems. That's a good sign. I am willing to educate myself. I would like to learn more about them. But reading the back-and-forth in this thread, I feel like I just walked into a graduate course in anthropology or French -- I understand a few of the terms being used, but it doesn't help me to understand any greater concepts.

Is there a fEARful-for-Dummies guide anywhere? I need to start at ground zero, with people breaking things down in potato-head language -- like their lives depended on making a 10-year-old understand what they're talking about.

Originally Posted by Queg

fEARful™ enclosures for bass/drums/keys

Originally Posted by ::::BASSIST::::

Here is a sound sample:

YouTube - Art of Noise fEARful

[BlueTalon]

Originally Posted by JimmyM

won't always be spudtalk...there is a learning curve to good audio principles. fortunately, it's still very easy just to plug one in and rock

[BlueTalon]

Originally Posted by BlueTalon

Fair enough. But "learn" comes before "know", and it's essential to establish someone's knowledge level before launching into an explanation. For starters, it's good to have a glossary for terms and acronyms. (I had my fill of acronyms in the military... then I get here and find people using them almost as much as the military does. It probably doesn't help that I have been out of the music world for two and a half decades...)

To put in another way, before the learning curve starts to really take off, it's best to make sure the prospective student is actually starting on the curve, and not just looking up at it. And that means making the beginning of the curve low enough for anybody to jump on.

[BlueTalon]

Originally Posted by DukeLeJeune

Others have given you links to ground zero, so I'll take a shot at a Dummies intro:

Many conventional bass cabs have inherent limitations: They don't really go very low, or they fart out while attempting to do so at well below their rated inpout power; they beam in the mids and/or highs so that the tonal balance changes significantly across a broad horizontal arc; those that have tweeters often have a "hole" in the frequency response between the top end of the woofer(s) and the bottom end of the tweeter; most cabs have a clearly audible "voicing" that may or may not be what you want, but it's usually hard to totally get rid of via EQ if you don't want it; and often it's hard for the bass player to hear what he's doing from where he has to stand. Now there are notable exceptions to the above generalizations, but the widespread incidence of such limitations is probably the raison d'etre for the fEarfuls.

The fEarfuls depart from conventional bass cab designs in using a single extremely long-excursion, high output woofer which is crossed over to a much smaller diameter, high-quality midrange driver. The cabinet design is very well thought out and executed, and (imho the most critical part) so is the crossover.

The fEarfuls bring together at least six winning attributes:

1) They have a wide enough radiation pattern that pretty much everybody in the house can hear what you're doing and hear it clearly. This is accomplished by crossing over to a wide pattern midrange driver well before the woofer starts to beam too much (the wider the source in relation to the wavelengths being reproduced, the narrower the radiation pattern; the narrower the source, the wider the pattern). For those who want the upper harmonics, the optional tweeter is likewise on a wide-pattern horn. A nice wide pattern not only gives better coverage, but more consistent tone because most of the sound that most people hear indoors is reverberant sound anyway, and this way there's enough mids and highs in the reverberant sound so that it's all good. And the mids and highs disperse widely enough for the bass player to clearly hear - and enjoy! - what he's doing. [As a speaker designer dude guy myself, the attention to radiation pattern is what impresses me most about the fEarfuls... it is simply the right sort of approach to a high-quality cab design, in my opinion anyway. If I weren't using a conceptually similar approach (different type mid), I'd be doing something virtually indistinguishable from the fEarfuls.]

2) The tonal balance of the fEarfuls is essentially neutral, so they become a blank canvas on which you and your bass and your amp and your effects can paint whatever you want. It doesn't start out with a characteristic tone that may or may not be what you want, but you can end up with what you want almost no matter what that might be. This is accomplished through intelligent driver choice, excellent crossover design, and a cabinet that is adequately sized and braced and vented.

3) The fEarfuls have enough excursion to take full advantage of available amplifier power up to the drivers' rated input. Most bass cabs "fart out" well below their rated power handling because the woofers don't have long enough excursion to move that much air without going severely non-linear (fartout).

4) They use premium quality lightweight components so their power-to-weight ratio is outstanding. I remember back when the F-16 first came out - it could sustain a 9-G turn 'till the tanks ran dry or the pilot blacked out or had a sphincter malfunction, and it could stand on its tail and accelerate (I'll never forget watching one rocket up to 20,000 feet, rolling as it did so to demonstrate that the wings weren't doing any lifting). Anyway, the fEarfuls have that sort of dominance in their theater of operations. Sorry for the mixing of metaphors there... gas turbine fumes...

5) The overall system design is extremely well thought out. The cabinet is ergonomically friendly, big enough to easily move your world but small enough that you can easily move it, the drivers all work well together, they are properly positioned for optimum performance, and really there is nothing that has not been carefully considered and optimized to the fullest practical extent.

6) The fEarful designs are freely published for private use, so you can build your own. Or if that's not feasible, there are authorized builders who can do it for you, and maybe nudge that power-to-weight ratio a click or two higher along the way.

In short, I think greenboy selected the right target set and delivered the right ordinance on those targets.

[markkoelsch]

I understand. There is a huge number of posts to wade through. Many of them are really good to read, but it may take more time than you want to spend.

I would start here:
http://http://greenboy.us/fEARful/

It is Greenboy's fearful site. Yes, it has links to the forum threads here, but also to other things. It might make it easir to sort through.

I know i am getting ready to build one myself...I have all of the drivers- I just need some time and my buds table saw.

[Selta]

I really can't wait to try one of these at a GTG later this month. I may be getting some new cabs down the line regardless, so I'm hoping that these "work" for me.

[colcifer]

Sticky?

[taphappy]

Originally Posted by markkoelsch

I would start here: http://http://greenboy.us/fEARful/

Oop. He would actually start here:

fEARful™ enclosures for bass/drums/keys

+1 on the sticky. Great intro by Duke, even with the fumes :)

[BlueTalon]

My first question:

Originally Posted by DukeLeJeune

3) The fEarfuls have enough excursion to take full advantage of available amplifier power up to the drivers' rated input. Most bass cabs "fart out" well below their rated power handling because the woofers don't have long enough excursion to move that much air without going severely non-linear (fartout).

That sounds like a function of the speaker, not of the cabinet.

Elsewhere in that thread, it was noted several times that you can't just swap out 15" drivers (well, you could, but...) without redesigning the cabinet for optimum performance. I vaguely understand that concept, but when you say the fEARful cabinet has enough excursion, what exactly does that mean?

[kesslari]

Having written about this topic many dozens of times, I'll venture that Duke was using shorthand.
He didn't mean that the CABINET has excursion - cabinets don't.

The cabinet was designed around a specific driver - the 3015LF - which has a TON of excursion. And often people speak about the fEarful to talk about the whole thing - which includes the drivers and the cabinet designed around them. So yeah, he was saying that the driver has a lot of excursion.

And so - to your other question. Different 15" drivers have entirely different sonic and performance characteristics. So just putting another 15" driver in your "fEarful" will substantially change it.
Just as putting a different engine in a Ferrari will substantially change the handling and performance characteristics of that car - even if the engine "fits" into the car.

Originally Posted by BlueTalon

My first question:



That sounds like a function of the speaker, not of the cabinet.

Elsewhere in that thread, it was noted several times that you can't just swap out 15" drivers (well, you could, but...) without redesigning the cabinet for optimum performance. I vaguely understand that concept, but when you say the fEARful cabinet has enough excursion, what exactly does that mean?

[Foz]

Excursion varies around the frequency band of the port tuning in a bass reflex speaker system.

Bass reflex - Wikipedia, the free encyclopedia

Thus, to discuss the excursion of the driver - in this context - you must consider the box it in.

[BlueTalon]

OK, thank you, that clears up some confusion. Now for the follow-up:

What about putting a Ferrari engine in something else? If the 3015LF has so much more excursion than anything else, why is it a bragging point for fEARful? Wouldn't it have just as much excursion in any other cabinet with vents or ports?


Oops -- posted before reading Foz's answer.

Foz, I understand how a port's size/shape/length can affect tuning, and thus indirectly affect speaker excursion. But what about large vents? It seems to me that with an opening of sufficient size, there would be no restriction on speaker excursion.

[Passinwind]

Originally Posted by BlueTalon

when you say the fEARful cabinet has enough excursion, what exactly does that mean?

He never said that, but probably most of us understand the cabinet to include the enclosure and the driver, as one system. How the enclosure is sized and tuned is critical to how the system performs.

The link Bill gave to the Parts Express primer provided in the last thread would answer all these questions and a lot more. But if you'd rather just take it a piece at a time here, that's cool.

[kesslari]

Originally Posted by BlueTalon

OK, thank you, that clears up some confusion. Now for the follow-up:

What about putting a Ferrari engine in something else? If the 3015LF has so much more excursion than anything else, why is it a bragging point for fEARful? Wouldn't it have just as much excursion in any other cabinet with vents or ports?


(Oops -- posted before reading Foz's answer.)

Right. You could stuff a Ferrari engine in a Kia, but the balance of the car, the handling, the suspension, steering, etc. would all be far from optimal to get the best performance out of that engine.

[DukeLeJeune]

Originally Posted by BlueTalon

That sounds like a function of the speaker, not of the cabinet.

Originally Posted by kesslari

The cabinet was designed around a specific driver - the 3015LF - which has a TON of excursion. And often people speak about the fEarful to talk about the whole thing - which includes the drivers and the cabinet designed around them. So yeah, he was saying that the driver has a lot of excursion.

Thanks, kesslari.

Okay, here's the deal with the 3015LF: Masssive excursion and low end, but crappy upper midrange and no highs. It's an engineering tradeoff.

The published frequency response shows a huge peak at 1.2 kHz, and that's the main cuprit. And as peaks go, it's an especially nasty-sounding one; I've seen others that look worse but don't sound as bad. The 3015LF is really a high-efficiency lightweight subwoofer driver that can get away with being used up to 800 Hz ballpark.

So if you're going to use the 3015LF in a bass cab and you care about quality and not just quantity, then you need to cross over to a midrange driver low enough and steep enough to suppress that huge peak, in order to avoid using it in the region where it sounds bad. This is easier said than done, but greenboy has done it and done it extremely well.

The smaller 3012LF has much better behavior in the midrange region, though it's not without problems as well. But it can be crossed over considerably higher up, in my opinion.

[rpsands]

The 3015LF is like a subwoofer and a midbass woofer in the same driver, doing the job you might otherwise need a huge 18" sub and a 10" midbass to accomplish. At least, that's what it seems like to me from looking at specs for more typical PA woofers.

[BlueTalon]

Originally Posted by DukeLeJeune

Okay, here's the deal with the 3015LF: Masssive excursion and low end, but crappy upper midrange and no highs. It's an engineering tradeoff.

The published frequency response shows a huge peak at 1.2 kHz, and that's the main cuprit. And as peaks go, it's an especially nasty-sounding one; I've seen others that look worse but don't sound as bad. The 3015LF is really a high-efficiency lightweight subwoofer driver that can get away with being used up to 800 Hz ballpark.

So if you're going to use the 3015LF in a bass cab and you care about quality and not just quantity, then you need to cross over to a midrange driver low enough and steep enough to suppress that huge peak, in order to avoid using it in the region where it sounds bad. This is easier said than done, but greenboy has done it and done it extremely well.

The smaller 3012LF has much better behavior in the midrange region, though it's not without problems as well. But it can be crossed over considerably higher up, in my opinion.

Thank you for your responses and your patience.

How are those frequency responses get established? From what I read, it sounds like they just bolted the speaker to the wall and stuck a microphone in front of it. (Very rough version, but the basic idea.) Do those published frequency responses actually help you to design a cab? How could they, if the initial measurements don't include a cab?

And then, does the cab design involve a lot of trial and error?

[nasr20de]

Sub'd

[rpsands]

Originally Posted by BlueTalon

Thank you for your responses and your patience.

How are those frequency responses get established? From what I read, it sounds like they just bolted the speaker to the wall and stuck a microphone in front of it. (Very rough version, but the basic idea.) Do those published frequency responses actually help you to design a cab? How could they, if the initial measurements don't include a cab?

And then, does the cab design involve a lot of trial and error?

It's a complex reason but basically measurement is the only way to plot the >200hz or so response with any accuracy -- the bolt it to a test baffle and measure it method. I don't pretend to know a lot about the measurement method but it's difficult to do because getting a good location where boundaries don't mess with the sound is tough, and good measurement equipment can be pricey.

The low frequency response is largely irrelevant to measure because with the TS characteristics you can plot out the LF response in any conceivable box using a good simulation program.

Hope that helps--basically, you measure for the mids/highs and simulate for the lows.

You *can* measure the lows in a cabinet, but it's not super relevant as a loud speaker seller because they can't control what cabinet you put the speaker in, only make suggestions.

Measured plots of the low end (and everything) in a cabinet would be useful for gauging response of a full cabinet system...but would again only tell a part of the story because the low end is limited by displacement, and 1w/1m measurements don't speak to displacement limitations.

[DukeLeJeune]

Originally Posted by BlueTalon

How are those frequency responses get established? From what I read, it sounds like they just bolted the speaker to the wall and stuck a microphone in front of it. (Very rough version, but the basic idea.) Do those published frequency responses actually help you to design a cab? How could they, if the initial measurements don't include a cab?

And then, does the cab design involve a lot of trial and error?

Yes, basically Eminence stuck a microphone in front of a speaker that's bolted in a wall. But they don't want room reflections included in the measurement, so they have to use some technique to exclude them. They can measure outdoors, in an anechoic chamber, or use electronic time-gating so that the microphone turns on and off before that first reflection arrives. This last technique is limited by room size (once the wavelengths become comparable to the distance to the nearest reflecting surface, your data is no longer reliable), so a different technique is used to mic the low frequencies - usually close-micing, wherein the microphone is placed very close to the cone such that the room's relative contribution is swamped by how much louder the cone is from so close up. The two curves are then "spliced".

Assuming the driver manufacturer's published data is accurate, yes that can help very much with the design process if you don't have the ability to make accurate measurements yourself. At a minimum, it will help with the driver selection process. Most cab manufacturers rely on their own measurements at the design stage.

At low frequencies, say below 200 Hz, the frequency response of a woofer and box combination can be accurately modelled based on the driver's Thiele-Small parameters. So we don't really care that the woofer was not in a cab when the factory curve was measured; we can figure that part out.

As for cab design, we try to do most of our trial and error using computer simulation programs, but at some point we have to go out to the workshop and make some sawdust, and then (if a crossover is involved) wire up some circuits and see if they a) behave like the computer predicted and b) sound like we hoped they would. In my experience, quite a bit of trial and error is involved, but the computer modelling gets us much closer on our first try.