10s vs. 15s

[Son of Bovril]

The best calculation is to find out how much money you have and then find all the cabs you can, within that budget and slightly above, and try them all...

Then save up buy the one that sounds best and is slightly above your budget.

 

[haujobb]

That's precisely the point. It doesn't matter how you get X amount of surface area in your speakers, one big driver, or many smaller ones. Its obvious in dollars because everybody can do the math easily to figure out the equivalency. Not so easy with complicated conical speakers.

Randy

I'm not buying it, I've never heard any cabs loaded with 10's that can pump out the lows like a good 18.

 

[specplyrz]

"That's precisely the point. It doesn't matter how you get X amount of surface area in your speakers, one big driver, or many smaller ones. Its obvious in dollars because everybody can do the math easily to figure out the equivalency. Not so easy with complicated conical speakers.

Randy"


I see now. OK. Good anolodgy.

 

[Big String]

I like 15" drivers better than 10" mostly because of the sound. No math here, just taste... hmmmm.
I seem to have read that a single driver is more "coherent" than multiples. Is this because there is no canceling as the waves cross each other...? There was a thread a while back about mulitple drivers in certain types of arrays, saying the tradtional "square" pattern of four did not perform as well as the "straight-vertical-tower" type of an array... at least for throw and on stage coverage. I could be soakin' wet .... just tossing in some other possible facts. I'm planning on auditioning a Bergantino NV215 in the near future.

 

[billfitzmaurice]

It doesn't matter how you get X amount of surface area in your speakers, one big driver, or many smaller ones

Ah, but it does matter. Sd is only one factor. There is the pesky matter of those other fourteen or so parameters to consider, and they all effect the result. Simply put, whatever you do to a driver to improve its bottom end also tends to hurt its high end, and vis-versa. The solution is to use different drivers for different frequencies, and not obess on which particular driver size is the one 'best' size, because there isn't any.

 

[theshadow2001]

Ah, but it does matter. Sd is only one factor. There is the pesky matter of those other fourteen or so parameters to consider, and they all effect the result. Simply put, whatever you do to a driver to improve its bottom end also tends to hurt its high end, and vis-versa. The solution is to use different drivers for different frequencies, and not obess on which particular driver size is the one 'best' size, because there isn't any.

Are you suggesting a bi-amp setup?

 

[getz76]

Are you suggesting a bi-amp setup?

Not exactly, but the right idea. In a perfect world where weight, cost, and durability is not a factor, active crossovers are great. However, using a mutli-way cabinet and a passive crossover is a good compromise.

There is no single driver that can reproduce the wide spectrum of bass guitar (especially when you start talking about a low B) at sufficient SPL for live use. Instead of using a 10" woofer to reproduce the entire frequency spectrum, why not use something to reproduce the lows and something to reproduce the highs? Or, even a 3-way, where you have lows, mids, and highs. Examples of three-way systems can be found; SWR (Triad), Acme (Low B), older Euphonic Audio, Dr. Bass, etc.

Three-way can be nice because there are very few drivers that are equally suited for both low-end response and midrange response. Usually, there is some sort of compromise.

 

[billfitzmaurice]

Instead of using a 10" woofer to reproduce the entire frequency spectrum, why not use something to reproduce the lows and something to reproduce the highs?

Exactly. The hi-fi industry caught on to this trick in 1927. The technology of an 8x10 isn't exactly cutting edge. In fact, it was 30 years obsolete before the first one was ever built.

 

[theshadow2001]

There is no single driver that can reproduce the wide spectrum of bass guitar (especially when you start talking about a low B) at sufficient SPL for live use. Instead of using a 10" woofer to reproduce the entire frequency spectrum, why not use something to reproduce the lows and something to reproduce the highs? Or, even a 3-way, where you have lows, mids, and highs.

Why dont manufacturers make specific low, mid and high bass cabinets? or low and mid/high cabinets. Each suited to a specific task? Do players just want convenience? Or is it the simple case that tradition and mis-information are the order of the day in the music world (it seems to me that this is true)

 

[getz76]

Why dont manufacturers make specific low, mid and high bass cabinets? or low and mid/high cabinets. Each suited to a specific task? Do players just want convenience? Or is it the simple case that tradition and mis-information are the order of the day in the music world (it seems to me that this is true)

Some do. It was more common when biamping was trendy.

The high frequencies can usually be carried by tweeters, so they usually are not in a separate box. Exceptions apply.

Typically, you see pro-sound offerings as "mains" and "subs", where mains carry the low-middle frequencies to the highs and subwoofers carry the lows. A decent sized club will likely have at least one subwoofer with some power behind it.

However, separate boxes require separate power amps. They also require crossovers (either passive, active, internal or external). This all also requires cabling. And cases. And cartage.

That's a lot. Yes, you can theoretically get an incremental benefit, but the cost-benefit yield isn't there. Some may argue it would be "better", but what we deal with can be "good enough."

 

[Kael]

The surface area enters into the amount of air that is moved when the piston moves in an out by a certain distance. This is equal to the frontal area of the cone, not the surface area.

That makes sense. Just gets my dander up when I hear the "surface area" of a cone calculated using the formula for a circle. I guess people are actually meaning the orthagonal projection of the cone onto 2D when they say surface area. Sorry, once again I'm a math nerd.

 

[seamonkey]

It works like a piston. The whole cone moves at once.
It's coned shape just for stiffness, not to increate the surface area.

 

[Mudbass]

It works like a piston. The whole cone moves at once.
It's coned shape just for stiffness, not to increate the surface area.

Surface area is not the only factor when determining how much air a speaker can move. Two 10's are bigger than one 15 if you simply add the diameters, but that tells you nothing about the displacement of the drivers. A cone shape is a mathmetical nightmare, but fortunately, folks who are a lot smarter than me have it all worked out and you can find the data in a speaker's thiele-small parameters.

The particular thiele-small parameter that concerns us here is peak diaphragm displacement volume (Vd). It is calculated by multipying Xmax (Voice Coil Overhang of the driver) by Sd (Surface area of the cone).

Now compare the Vd of these two speakers, an Eminence Magnum 15HO and an Eminence Kappa Pro10. The Vd parameter on the 15HO is 411cc while the Vd on the Pro10 is 110cc. I think we can assume that four Pro10's combined in a 4x10 cab can displace 440cc of air. Well golly jee, that's not a whole lot more than a single 15! Put two 15's in a box and we're talking about 822cc of displacement. Now that's a force to be reckoned with.

 

[specplyrz]

"Now compare the Vd of these two speakers, an Eminence Magnum 15HO and an Eminence Kappa Pro10. The Vd parameter on the 15HO is 411cc while the Vd on the Pro10 is 110cc. I think we can assume that four Pro10's combined in a 4x10 cab can displace 440cc of air. "

I knew it was four to one...basicly.....I have used 15's only, Guild Hartke, two of them with an SVT pro II...all tube head. My 810e bottom has a fuller tone but those Hartke's really cut through!!

 

[billfitzmaurice]

The Vd parameter on the 15HO is 411cc while the Vd on the Pro10 is 110cc. I think we can assume that four Pro10's combined in a 4x10 cab can displace 440cc of air.

'Tis of no consequence. The fs of the Magnum is 33Hz, that of the Kappa Pro 46 Hz. The Kappa Pro Qts is .20, that of the Magnum .27. Bottom line, the Kappa Pro isn't worth diddly squat below 150 Hz, while the Magnum 15HO is OK to a full octave lower. If all that was required to get it loud and low was to move a lot of air we wouldn't use speakers, we 'd use fans. There's a reason why there are (at least) fifteen Theile/Small parameters.

 

[steveksux]

Randy, I'm still with Bill Fitzmaurice on this one, but I'm certainly no expert, and very interested to find out more.

As you said yourself, the cone area isn't the only factor, there are many other parameters involved. In particular, the resonant frequency of the driver will generally be lower for larger drivers. As far as I'm aware, the enclosure has an effect on this, but only to raise it (in a sealed cab), or split it (in a ported cab). Will using multiple 10s change their resonant frequency to that of a single 15? The frequency plot of large and small drivers is going to be different, surely?

Is Billfitz disagreeing with me? Add enough 10's, you would have or exceed cone mass, cone area, etc.... Hard to say about the resonant freq. Mass is involved in that, surround flexibility, etc. That could be a flaw in my theory. But bottom line, the tuning of the cab and its design have more effect than the size of the drivers, IMO. I would certainly NOT make the decision because I thought 15's sound like this, 10's sound like that. There are 10" based cabs that put out as much or more bottom that some 15" or even 18" cabs. EA comes to mind.

You're ears tell you all you need to know. It's not how big it is, its what you do with the driver.


Randy

 

[steveksux]

I'm not buying it, I've never heard any cabs loaded with 10's that can pump out the lows like a good 18.

I used to use a bag end 18" with a 4x10 stacked on top.

I now use a pair of 2x10" cabs from EA, and the low B is solid as a rock. Better than I had with the previous setup.

Randy

 

[steveksux]

Or, even a 3-way,

A 3 way is almost always a good idea.

Randy

 

[Mudbass]

'Tis of no consequence. The fs of the Magnum is 33Hz, that of the Kappa Pro 46 Hz. The Kappa Pro Qts is .20, that of the Magnum .27. Bottom line, the Kappa Pro isn't worth diddly squat below 150 Hz, while the Magnum 15HO is OK to a full octave lower. If all that was required to get it loud and low was to move a lot of air we wouldn't use speakers, we 'd use fans. There's a reason why there are (at least) fifteen Theile/Small parameters.

I used those two speakers to illustrate the difference of the Vd spec between a 10 and a 15 and that surface area alone doesn't tell you much. You're right, the volume of air a speaker can displace is of no consequence...unless you want to be heard past the first row of seats that is.

 

[BassyBill]

Is Billfitz disagreeing with me? Add enough 10's, you would have or exceed cone mass, cone area, etc.... Hard to say about the resonant freq. Mass is involved in that, surround flexibility, etc. That could be a flaw in my theory. But bottom line, the tuning of the cab and its design have more effect than the size of the drivers, IMO. I would certainly NOT make the decision because I thought 15's sound like this, 10's sound like that. There are 10" based cabs that put out as much or more bottom that some 15" or even 18" cabs. EA comes to mind.

You're ears tell you all you need to know. It's not how big it is, its what you do with the driver.


Randy

I said I'm with Bill on this one because like him I tend to think that combinations of drivers are the way to go. Look at any decent sound system (hi-fi, PA, whatever). I think if you want to cover a wide range of frequencies (and amping basses comes into this category) then you're not going to do it as well with a single size of driver, even in multiples, as you are with specialist ones for each frequency band. I know bi-amping, like Hartke , is out of favour amongst bassists at present, at least on this forum, but to me it's intuitively the best engineered solution for the job, passive crossovers being a close second (for efficiency reasons). My requirement for a bass amp is clarity across the full range of frequencies and my Hartke bi-amped setup gives me this. Whenever I've tried just using a 410 or, way back, a 412, the sound was too "coloured" for me.

Just what I prefer I guess. I know a lot of guys like less of a hi-fi sound (I use this term in the clarity sense, rather than the scooped mids sense common on TB - I don't associate biamping with a scooped sound, nor is there any reason why it should be AFAIK).