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Are 15's too slow....

#42
bgavin said:
Adire did a study on the fast vs slow thing, with interesting results.

After the math and smoke cleared, Adire demonstrated by measurements that transient response wasn't tied to motor strength to mass ratio (BL:MMS). The big point Adire made was the inductive delay inherent in energizing any coil. The larger the coil inductance, the longer time required to energize that coil, hence a response delay. Remember ELI the ICE man?

The part of the study that Adire did not address to my satisfaction was the "real world" part of the equation. This is the part where the driver has real mass, and requires more than instantaneous response to get moving. There is inertia in the cone, and acceleration of that cone. This is the part where I think a driver can be "slow" in that it accelerates poorly (slowly), then has a tendency to overshoot when the signal reverses. Inertia and mass, again.

A 4-cylinder Yamaha rice rocket has a much higher BL:MMS ratio than does a Chevy Suburban. This equates to much faster acceleration in the rice rocket.

I put BL:MMS ratios in my spread sheet for those interested in them (me). Dunno if they are truly valid, but they do provide a useful apples-to-apples comparison. The 10" win every time.
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I'd be willing to bet that the air in the enclosure, along with the porting and resonant freqs exhibit more force against the cone than the actual inertia of the cone anyway. Looking at the speaker by itself doesn't give you the whole picture.

Besides which, at mid freqs, doesn't the cone reproduce sound by breaking up anyway, its no longer a piston. Stiffer cones resist this, and reproduce lows better at the expense of mids, less stiff cones don't behave as piston like, do worse for lows, but they reproduce highs better. At those freqs, only part of the cone is reproducing the signal anyway, the inertia of the entire cone doesn't matter. The cone is flexing so that the central part is doing all the work, near the voice coil.

Too many variables involved. Any generalizations made have too many exceptions to draw any useful conclusions. You end up with a situation where my 2x10 EA cabs put out a more solid low B than my 1x18 Bag end did, even though that totally flies in the face of bigger drivers=better low end.

The only way to be sure is listen.

Randy
 
#43
Besides which, at mid freqs, doesn't the cone reproduce sound by breaking up anyway, its no longer a piston.
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The problem here is that in so many cases the dust cover serves as a midrange radiator, and T/S specs are insufficient to predict its behavior. The most extreme case would probably be an EVM12L, which has -6dB axial response up around 7kHz, all sourced from the dome, and not accounted for by T/S, which only can consider the cone as a complete unit rather than a woofer cone plus 4" midrange dome. An EVM15B doesn't go near as high, but it does go a lot higher than perhaps 80% of available tens. Accurately modeling an Altec Bi-Flex would also be impossible, as would be anything with a whizzer cone. The only driver styles that come to mind where T/S would be completely accurate would be porous dome woofers like the BP102, or large dome drivers like the HL10a, where the dome is the cone. The Adire study has relevence as far as pure woofers are concerned, which is logical since pure woofers are Adire's forte. But applying the results of that study to wide-range drivers, especially those with a high fs and a low-mass solid dust cover, would probably lead to very inaccurate conclusions.
 
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#44
with all this technical jargon it sounds like as long as you have a decent set of cabs, the crossover is just as important as the speaker and cab.
Art Vandelay designed a series of bass cabs with reflex technology johnson rods installed. He used his resources in his latex salesman position to make these really cool looking covers. Much better than tolex or carpet. They were, unfortunately, very heavy, and he had to use roadies ( Slippery Pete and Schlomo) to transport these things around.
 
#47
A 15 has more bass and a fatter overall sound, so having one below your 10s keeps you from turning up the bass control on your amp, making your power amp clip and your 10s melt. IME.

I didn't like the 12" loaded cab I tried (an aggie), I far prefer the combo of 10s and 15s together. They complement each other perfectly.
 
#50
metron said:
honestly i dont think ive ever heard a "slow" speaker.
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Of course you haven't. The terms fast and slow have both been applied to speakers, especially sub-woofers, most especially auto sound sub-woofers, primarily by the younger set who often lack both the technical knowledge and technical vocabularly to properly express what it is that they're trying to describe.
 
#51
Maybe so, but I think in this case it's accurate. 15"s do feel like they respond slower than 10's to me. I don't know what causes it and frankly I don't care. It's in the way the note blooms (there's another good technical term there). Like it takes just that little bit of lag time for the note to reach its fullest potential as opposed to the 10's, which seem to hit it right away.
 
#52
The perception of slowness probably has to do with the attack of a note being mostly high mids and highs, which the 10" is putting out more of. With the 15 you're hearing less attack and more of the full part of the note. When you use 10s and 15s together, you get both.
 
#53
one of the age old debates indeed.

at the end of the day, i think the consensus is that speakers are neither "fast" nor "slow". they just are. getting into semantics only is a thin veil, hiding the fact that EVERYTHING goes thru us - human filters. our preconceived notions, others' opinions and perceptions weigh more heavily into how the system "sounds". and adding to that, things like your environment will have MUCH more influence on the "sound" of the system than things like moving mass and BL product and inductance. sure it's fun talking about this stuff, but i think it's more important to talk about how WE love using it, and enjoying it! i know i do. :bassist:

a good friend of mine said something spot on about woofer "speed" and such:
the bass was so fast, it left the room before i could measure it.
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anyway..me $0.02
 
#54
I would use the term "flabby" or "muddy" rather than "slow".

I happen to prefer the sound of 10 inch speakers, as (in my experience) they can usually go low and still retain definition. Larger speakers often sound flabby to me. However in certain band contexts "flabby" might sit in the mix just right.
 
#55
etnops said:
one of the age old debates indeed.

at the end of the day, i think the consensus is that speakers are neither "fast" nor "slow". they just are. getting into semantics only is a thin veil, hiding the fact that EVERYTHING goes thru us - human filters. our preconceived notions, others' opinions and perceptions weigh more heavily into how the system "sounds". and adding to that, things like your environment will have MUCH more influence on the "sound" of the system than things like moving mass and BL product and inductance. sure it's fun talking about this stuff, but i think it's more important to talk about how WE love using it, and enjoying it! i know i do. :bassist:

a good friend of mine said something spot on about woofer "speed" and such:

anyway..me $0.02
Click to expand...


A terrific post IMO.
 
#56
billfitzmaurice said:
Of course you haven't. The terms fast and slow have both been applied to speakers, especially sub-woofers, most especially auto sound sub-woofers, primarily by the younger set who often lack both the technical knowledge and technical vocabularly to properly express what it is that they're trying to describe.
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Some of us are old enough to remember with amusement when hi-fi makers went through a fad of advertising "fast bass."
 
#57
I have a 2 x 15" and a 4 x 10" cab... both high-dollar & high-quality brands. When our little guitar player first showed up, I played through my 2 x 15" during practice sessions. One day I decided to bring out the 4 x 10". He tells me how much more he likes my sound through the 10s... Me!... and old-guy bassits from the early 70s. All I ever knew was 15-inch drivers! I was mortified!

So, we go to gigs. Mostly I bring along the 10s 'cuz the size of the venues are pretty small, as well as the stages, and volume is a definite issue... we play 60s & 70s rock classics, with a few 80s hits sprinkled-in. We almost always get together Sunday afternoons for practice, and usually the following Monday night, but if the Cowboys are televised, then no practice; however, they lost to the Giants last week, so... oh, well, I digress! Please forgive me... :crying:

One recent Sunday session, I brought out the 15s. I was going to introduce my little guitar player to the magic of 15-inch bass speakers. He noticed that I didn't have the 10s set up, but he didn't say anything. After about an hour into our practice, he commented how great my sound was, and that he couldn't believe it was coming from my 2 x 15" cabinet. He wanted to know what, if anything, I had done differently to produce this "incredible" (his word... not mine... but I know it applies!) sound.

So, I proceeded to explain to this young little whippersnapper. He's eleven years younger than me, so I figure the lad needed some learnin' about the bottom line! The first few times he heard my 15s, I was using my Ashdown ABM500 Evo-II. We played at a normal volume, but I didn't choose to over drive my sound at the time. Also, we practice in my 10,000 sq. ft. warehouse, and we stand fairly close to each other... a necessity due to power access, as well as available space... so he hasn't had a chance to really step away from my cabinets to appreciate what they are truly doing.

I haven't used my Marshall VBA400 with this guy, because she really needs to be played at a relatively high level in order for her to really start singing. We haven't played a venue yet that will allow me to show-off this beast. This little guitar player knows I have the Marshall, and he keeps bugging me to bust her out, but I keep stringing him along by telling him, "One day you shall be worthy, young Weedhopper, but not yet..."

Well, the day he finally heard my 15s was a session when I chose to play my Aguilar DB750. It had taken me a little bit of time to get acquainted with this amp. What I had done to impress my little guitar player was really nothing at all. I simply chose to over drive the pre-amp. I set the Master at about 7 o'clock, and then cranked the Gain up to about 2 o'clock. I fooled around with the EQs, but mainly bumped the mids up some. What he heard was 2- fifteen inch bass speakers do what they've been famous for doing the last 40-odd years that I've been listening to them... THEY ROCKED!

The boy loves my 15s... now!

And then there was the session when I hooked both cabs up to the Big Daddy Aggie! :eek: The 2 x 15" is an NV215, and the 4 x 10" is a D410XLT... both are 4 Ohm. Ever since that particular Sunday, my little guitar player... with his 100-watt Marshall... no longer questions my sound. I still haven't allowed young Weedhopper to experience my Marshall, but someday, as he does show promise, he will become worthy... :D
 
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