Cones

[action_panzer]

What are your cone size preference and why?

I'm a 15" man (LADIES!), I like the whump and trouser-flappability, although I might just be saying this because I've never actually tried anything else. Discuss!

[xgsjx]

Cone size makes no difference to the sound. It's all down to how the driver is made & cab design.
The benefit a single 15 has over a single 10 or 12, is that it can move more air. a 2x10 can move almost as much air & a 2x12 can move more air, but the disadvantage there is more magnet weight (though with neo, that's hardly an issue).
To top that off, PJB use 5" drivers (I believe their bigger cabs have 21 of them).

So to put it simple, the more air you can move, the louder you can go.

[Phil Starr]

[quote name='xgsjx' timestamp='1387014944' post='2307384']
Cone size makes no difference to the sound. It's all down to how the driver is made & cab design.


So to put it simple, the more air you can move, the louder you can go.
[/quote]

[Phil Starr]

Sorry, but this simply isn't true, though it has become the received wisdom on BC.

Size matters in a number of ways and the radius of the cone is an important factor in predicting it's performance. It occurs in a number of the calculations designers use. The other factor in speaker cones is their mass, and bigger cones are heavier. Heavier cones have a lower resonance and can reproduce deeper notes as a result. You can make a small cone go deeper by adding weight but this will make it quieter, or by loosening off the suspension but this will affect it's sound too, again in complex ways. For example a thicker cone with a loose suspension is more likely to act as a piston and not flex, this will reduce the high frequency content and probably lose the mid-range hump which gives the characteristic sound of many bass speakers.

It also isn't true that a 10" speaker travelling twice as far will be as loud as a 15 or two 'ordinary' 10's. speakers produce very high energy high pressures at the cone, Sound is normally spread over a large volume and the pressures are much lower, there is an impedance mismatch at the point the speaker meets the air and energy is transferred inefficiently. Horns act to match the impedance of the cone and air and that is why they are louder, They aren't making energy they are simply converting it more efficiently. Increasing the cone area will do this as well, doubling cone area and will give you a 3db increase in sound level for the same electrical input.

Of course size isn't everything and there are many other factors, the electromagnetic motor and the detailed design of the cone. Alex Claber explains this perfectly fairly (from memory as his site is down) in saying there isn't a sound of a 15 or a 10" speaker. There are so many variables it couldn't be, but it isn't insignificant either, if you wanted a loud, efficient speaker driving down to 30Hz you wouldn't start with a 4" speaker.

[RandomBass]

BF site seems to be up for me, but then I'm in the same postcode area lol. Is this the page you were referring to Phil?

[url="http://barefacedbass.com/technical-information/speaker-size-frequency-response.htm"]http://barefacedbass.com/technical-information/speaker-size-frequency-response.htm[/url]

[Phil Starr]

Yep, it's working again now. My computer is almost as ancient as I am so I do get odd glitches

[Bill Fitzmaurice]

[quote name='xgsjx' timestamp='1387014944' post='2307384']
Cone size makes no difference to the sound.
[/quote]Cone size has a direct effect on the angle of dispersion. When the cone is one wavelength or more across dispersion narrows; a cone that's too large for the frequency being radiated is what causes beaming. While larger cones tend to have better low frequency response, and smaller cones tend to have better high frequency response, those are not absolutes. Dispersion is, and it's the primary reason why midranges are smaller than woofers, and tweeters smaller than midranges.
A relevent point is that when two drivers are placed side by side the horizontal dispersion is the same as if they were one driver twice their size. Thus a pair of tens side by side have the horizontal dispersion of a twenty inch driver, explaining why a fifteen can have better highs off-axis than a two ten cab. Twelves side by side are even worse. Almost every guitar player running cabs with side by side twelves complains about beaming, as do those in the audience in front of them who get their heads taken off by even an AC 30, let along a stack, while those standing to the side can't hear them at all. The physics involved are quite simple, but few guitarists have a clue how speakers work, beyond "you plug an amp into them".

Edited December 14, 2013 by Bill Fitzmaurice

[JTUK]

Just listen to typical 15's, 12 and 10's and then you'll know that cone size have definite bias'

I like 10's but have a 212 that really works well.
I have other 2x112's which don't cut it..even though many would say they make
the best cabs out there.

[xgsjx]

[quote name='Phil Starr' timestamp='1387018133' post='2307413']
Sorry, but this simply isn't true, though it has become the received wisdom on BC.
[/quote]

I think you may have misunderstood what I was saying, though I could have worded it a little better. But maybe a good thing as you then went on to explain quite a few things.

What I meant was that a driver's diameter doesn't mean it has a particular sound. It's down to lots of factors.
The 2 15" Marshalls that I had in the 80s had nowhere near as much bass as the 2x10" Makbass that I use nowadays. Though this is most likely a mix of better designed drivers and better designed cabs.

[Bill Fitzmaurice]

[quote name='xgsjx' timestamp='1387069801' post='2308013']
What I meant was that a driver's diameter doesn't mean it has a particular sound.
[/quote]+1. Within reason you can get pretty much the same result with any cone size from an eight to an eighteen, with the single exception of the dispersion angle. It isn't all that practical to get 30Hz out of eights, or 4kHz out of eighteens, but it can be done. There is absolutely no characteristic ten vs twelve vs fifteen sound.

[xgsjx]

[quote name='Bill Fitzmaurice' timestamp='1387076258' post='2308043']
+1. Within reason you can get pretty much the same result with any cone size from an eight to an eighteen, with the single exception of the dispersion angle. It isn't all that practical to get 30Hz out of eights, or 4kHz out of eighteens, but it can be done. There is absolutely no characteristic ten vs twelve vs fifteen sound.
[/quote]

A couple of weeks ago, my guitarists found out what dispersion is when the room we hired had a 4x12 guitar cab, stood right in front of it & kept turning it up because he couldn't hear himself. I suggested that he move further away & he stepped forward & to the side. He still thought he was quiet.
The other guitarist pulled him over to where he was standing, straight across from the cab & he stood there for the rest of the sesh (& turned down too).

[Bill Fitzmaurice]

[quote name='xgsjx' timestamp='1387101526' post='2308142']
A couple of weeks ago, my guitarists found out what dispersion is when the room we hired had a 4x12 guitar cab, stood right in front of it & kept turning it up because he couldn't hear himself. I suggested that he move further away & he stepped forward & to the side. He still thought he was quiet.
The other guitarist pulled him over to where he was standing, straight across from the cab & he stood there for the rest of the sesh (& turned down too).
[/quote]Not the sharpest tacks in the bin they are. I once mixed a band where the guitar player insisted that he not be mic'd. As I knew would be the case he couldn't be heard outside of a small cone shaped area directly in front of his cab. First break he asked how he sounded. I told him I didn't know, since ge wasn't in the PA I couldn't hear him. His solution? Turn his amp up.
Needless to say that did not improve matters a whit.
Go to a guitar forum and you see them go on forever about this speaker, that pedal, these strings, those picks, all in search of a magical tone that will make them the next Clapton, yet most are profoundly clueless about how to get said tone heard by more than 15% of the audience.
The best player I've seen since Mike Bloomfield is John Mayall's current guitarist. His Fender Twin is aimed across the stage at the drummer. He doesn't hear it directly, like the audience he hears it through the PA.

Edited December 15, 2013 by Bill Fitzmaurice

[stevie]

The other factor that I've never seen anyone mention is that smaller cones have a superior midrange performance to larger cones - given an equivalent technology level, of course. So at mid frequencies (say 500Hz up) a 10 will always have lower distortion, fewer delayed resonances and a higher natural breakup frequency than an equivalent 12 or 15. I think this is probably why many bass players like 10s.

[funkle]

Subscribed.

I just paid for a set of BFM plans because I wanted to see how Bill designs a bass reflex cab. I am grateful he continues to post here, now that Talkbass is forbidden territory. I am also extremely grateful for seeing input from regulars here too, I'm learning a great deal from Stevie and Phil on this and other threads.

Quick question. When designing a three way or two way full range system, how do you decide where to cross over? When polar response starts to drop off at the woofer, when SPL drops off, other...? I assume cone size matters here when designing as polar response vs frequency will be different between cone sizes, as pointed out already...

Pete

[LukeFRC]

[quote name='funkle' timestamp='1387135186' post='2308559']
Subscribed.

I just paid for a set of BFM plans because I wanted to see how Bill designs a bass reflex cab. I am grateful he continues to post here, now that Talkbass is forbidden territory. I am also extremely grateful for seeing input from regulars here too, I'm learning a great deal from Stevie and Phil on this and other threads.

[/quote]

+1
I didn't even realise until yesterday Bill wasn't on TB anymore, no idea why (I don't want to know) but it's their loss!
I heard an Omni 15 last month and it was EPIC.

Mind you TB is an odd place I was reading all this hype for some "vortex" speakers and then went and looked at other more pro audio design forums... different response there!...

[Bill Fitzmaurice]

[quote name='LukeFRC' timestamp='1387137630' post='2308598']
+1
I didn't even realise until yesterday Bill wasn't on TB anymore, no idea why (I don't want to know)[/quote] Explained here:
http://billfitzmaurice.info/forum/viewtopic.php?f=7&t=18092
[quote]Mind you TB is an odd place I was reading all this hype for some "vortex" speakers and then went and looked at other more pro audio design forums... different response there!... [/quote]Those speakers attempt to defy the laws of acoustics. They fail in that attempt. But as our President Lincoln famously said (and probably paraphrased Shakespeare in so doing) you can fool some of the people all of the time.
[quote]When designing a three way or two way full range system, how do you decide where to cross over? When polar response starts to drop off at the woofer[/quote]That's the primary concern, or should be anyway, but you do have to balance it against cost, as the lower you cross over the more expensive the components, not just for the driver but also the horn and crossover components. In a cost no object design I'd go even lower than I did with the Simplexx, but for most builders cost is an object. Most commercial cabs go too far in the other direction where that's concerned, and cross over way too high. Oddly enough the only ones who benefit from their cost savings are themselves.

[LukeFRC]

[quote name='Bill Fitzmaurice' timestamp='1387146785' post='2308809']
Those speakers attempt to defy the laws of acoustics. They fail in that attempt. But as our President Lincoln famously said (and probably paraphrased Shakespeare in so doing) you can fool some of the people all of the time.

[/quote]
I heard your Omni and was dead impressed so trying to learn about different speaker designs and what a horn was, what a folded horn, tapped horn, how they worked and all that... still not really sure of everything but understand a bit... your posts are helpful thanks!
anyway stumbled upon the physics defying cabs and tried to work out what on earth they were talking about... well reading their interesting explanation and a bit of googling and I think I worked out what tech they're trying to use - but for my life of me I couldn't work out how it supposedly works - doubt it's patentable mind. Anyway some day I'll build my own cab, to your or someone cleverer than me's plans

Edited December 15, 2013 by LukeFRC

[Bill Fitzmaurice]

[quote name='LukeFRC' timestamp='1387147740' post='2308823']
stumbled upon the physics defying cabs and tried to work out what on earth they were talking about...
[/quote]What they've done is to take a bass reflex cab and put a reflector inside that directs the driver rear wave out the ports. It's been known since the 1940s that if you do that the front and rear waves will meet at various angles of phase, resulting in major reponse peaks and valleys. And since the 1940s bass reflex cabs have used damping inside the cab to prevent that, allowing only bass frequencies close to the port tuning frequency to come from the port. Damping the rear wave is one of the most basic tenets of speaker design, but these guys have managed not to learn that. The other feature they use is cross-fired drivers, but that's hardly new or unique. They use extremely expensive drivers, so their prices are off the charts. But they look cool.

[Phil Starr]

[quote name='xgsjx' timestamp='1387069801' post='2308013']
I think you may have misunderstood what I was saying, though I could have worded it a little better. But maybe a good thing as you then went on to explain quite a few things.

What I meant was that a driver's diameter doesn't mean it has a particular sound. It's down to lots of factors.
The 2 15" Marshalls that I had in the 80s had nowhere near as much bass as the 2x10" Makbass that I use nowadays. Though this is most likely a mix of better designed drivers and better designed cabs.
[/quote]That's all fair,

I hope you didn't think it was a personal thing I'm an ex science teacher and I can't resist my instinct against the unqualified statement. My wife is an English teacher and can't resist correcting my grammar. Hope it opened up the debate though.

[Beer of the Bass]

I looked up the makers of the "vortex cabs", and was amazed by their FAQ. I can't help but feel that they're just trying to intimidate the reader with words they borrowed from Steven Hawking books, and that they might as well have just said "Magic". Bill's description above is much clearer and doesn't conflict with any of the behaviour of sound waves which I recall from high school physics classes!
[url="http://bigeloudspeakers.com/faqs.htm#What%20is%20MVW"]http://bigeloudspeakers.com/faqs.htm#What%20is%20MVW[/url]

[Phil Starr]

[quote name='stevie' timestamp='1387116529' post='2308304']
The other factor that I've never seen anyone mention is that smaller cones have a superior midrange performance to larger cones - given an equivalent technology level, of course. So at mid frequencies (say 500Hz up) a 10 will always have lower distortion, fewer delayed resonances and a higher natural breakup frequency than an equivalent 12 or 15. I think this is probably why many bass players like 10s.
[/quote]

Hi Stevie, to be fair it is a little more complex than this and a bit more tricky for designers. A 10" speaker will only normally operate as a rigid piston up to 1200Hz above this the beaming starts and the weight of the cone becomes harder to accelerate and decelerate causing all the problems you mention. To deal with this most if not all bass speakers operate with some (hopefully controlled) flexing of the cones. If you wanted to cover from 500 up to say 5000Hz you'd need a tiny 6cm driver like the dome mid-ranges in hi fi speakers. To get the 500Hz energy involved in bass applications you'd have to have a driver this size horn loaded..

All the things you say are true of a lighter cone but once the cone starts flexing it depends upon where it flexes, and it is possible to design a 15 with the right flexure and cone damping to reproduce better mids than a 10 that has a beefed up, thicker and heavier cone designed to go down to 40Hz.

This flexure means also that the radiation or dispersal pattern for large drivers isn't always as poor as stated, A 15 may be radiating most of the mids using the central few cm of the cone.

For me it seems that if you want lots of deep bass you are better off with a large diameter cone, if you want good undistorted mids and good dispersion then smaller lighter cones are a better starting point but you can make a small cone go deep and get good highs out of a big cone by making compromises in their design. Nearly all of these compromises have been tried by somebody at some time.

[stevie]

Phil, I appreciate that you can put a more complex spin on it, but let’s not compare apples and oranges. Yes, you can make an expensive 15 that will have better midrange than a cheap 10 and you can even make a 10 that has no midrange at all. But it is still the case that (ceteris paribus) large cones are simply not as good at reproducing higher frequencies as smaller cones, and that the larger the cone the lower it tends to break up.

By the same token, when a lot of air has to be moved you need a large cone area. It’s the balancing act that makes speaker design so interesting, don’t you think?

[stevie]

[quote name='funkle' timestamp='1387135186' post='2308559']
Quick question. When designing a three way or two way full range system, how do you decide where to cross over? When polar response starts to drop off at the woofer, when SPL drops off, other...? I assume cone size matters here when designing as polar response vs frequency will be different between cone sizes, as pointed out already...
[/quote]

I agree with Bill on this one. Most drivers have an on-axis response that is wider than their ‘usable’ response - so crossing over where their natural on-axis response drops is normally not a great idea because the drivers are usually well out of their comfort zone by then. Because you and your audience hear a combination of on-axis and off-axis sound from your bass rig, what you want to achieve is a smooth, well-behaved off-axis response that duplicates the on-axis response, although decreasing in level the further you move off-axis.

So, if “constant directivity” is your aim, which it should be, a good [i]rule of thumb[/i] is to cross a large speaker over (to a smaller speaker) before its off-axis response has dropped more than, say, 3dB. That’s the ideal I’d aim for, although it’s not etched in stone.

There are certainly other factors to take into consideration, but let’s not get too carried away.

[alexclaber]

Doug Button of JBL wrote a very good paper about some of this stuff: https://secure.aes.org/forum/pubs/conventions/?elib=5524

[stevie]

Doug Button is always worth reading but I'm afraid mere mortals cannot access that website.