18inch Monster

[4 Strings]

I've never tried a Briefcase or Suitcase type amp, I know bigger and bigger sounds are coming from smaller speakers nowadays, but I've just bought a Hartke 1800 and its nuts!

I love a bass sound offering a wide range of frequencies, so a 2.5XL cabinet (2x10 + 5") plus this monster gives the most huge sound, surely not available from small size cabinets. The sound volume is huge and the deep frequencies particularly satisfying, all from this huge speaker, its huge cab and the ports.

Can a small cab do it?

[Brave Sir Robin]

I've always understood it is much easier (and cheaper) to get powerful ultra low frequencies with a large speaker, at the expense of poor higher frequency response. Not really an expert, but I'd love to hear an expert opinion about the qualities of large speakers vs small speakers for reproducing low frequencies at high volumes.

[Bill Fitzmaurice]

[quote name='Brave Sir Robin' post='1010201' date='Nov 2 2010, 07:37 PM']I've always understood it is much easier (and cheaper) to get powerful ultra low frequencies with a large speaker, at the expense of poor higher frequency response. Not really an expert, but I'd love to hear an expert opinion about the qualities of large speakers vs small speakers for reproducing low frequencies at high volumes.[/quote]
Driver size in and of itself is moot. Where low frequency output capability is concerned what matters is driver displacement, sensitivity and frequency response. Those are related to driver size, but only anecdotally.

[Brave Sir Robin]

Just entertaining a thought, but from a purely mechanical point of view, a bigger cone will certainly make a bigger displacement easier, and will move a lot of air by itself relatively easily. Unless your small cone design has some funky engineering allowing it to move back and forth a lot without shredding itself to pieces. Hence my point regarding how easier and cheaper it is to produce a large speaker than an array of small, high quality, higly durable 10'' speakers.

Or then again, I could be wrong.

[Bill Fitzmaurice]

[quote name='Brave Sir Robin' post='1010231' date='Nov 2 2010, 08:12 PM']Just entertaining a thought, but from a purely mechanical point of view, a bigger cone will certainly make a bigger displacement easier, and will move a lot of air by itself relatively easily. Unless your small cone design has some funky engineering allowing it to move back and forth a lot without shredding itself to pieces. Hence my point regarding how easier and cheaper it is to produce a large speaker than an array of small, high quality, higly durable 10'' speakers.

Or then again, I could be wrong.[/quote]
The cost per cc. of displacement does go down as the size of the cone goes up. But as already noted larger cones are generally accompanied with less high frequency extension, and are always accompanied with narrowed dispersion, so there is a point of diminishing returns. IMO there's no advantage to going larger than a fifteen, and I wouldn't even use a direct radiating fifteen on its own without a midrange driver, due to the midrange beaming issues with a fifteen.

[4 Strings]

Big 'bins' like the 1800 aren't designed to be used on their own and the sound on its own isn't one I would choose.

Low frequencies are largely non-directional so any 'beaming' qualities of larger diameter cones will be irrelevant (not heard of that before - in old PAs it was always the high frequency horns which had directional lenses) especially if used with another cab with smaller cones.

Clearly, despite an enormous magnet or 'motor', a massive 18" cone like this is not going to move about as quickly and as subtle as a smaller, 10" or even 5" cone and so will not be able to reproduce high frequencies so accurately or efficiently. 2 and 3 way speakers have been common in hi-fi for many years (accepting that its difficult to make a 3 way improve on a 2 way). Anyone remember the Bose PA speakers of yesteryear? Amazing loudness and bass response from 8 x 4" cones in each cab, but they needed a special equaliser to work.

Cabinet volume is important (hence the smaller bass handling cabs being very deep - eg the new TC Electronic 112 - cheaper slim cabinets always sound boxy) and the length of port possible will help. No transmission line here, but four ports about 100mm dia and ~400mm long, not possible in a small box.

I am not a speaker cabinet designer, black art to me, but I remember asking a glider pilot friend of mine whether new technology is reducing the span of glider wings, he responded this was kind of true but there's no substitute for span. I wonder if this is the same here, smaller boxes can mimic with ever increasing accuracy but there's no substitute for volume. Even if small cones can be made to work a lot of them will be needed.

Edited November 3, 2010 by 4 Strings

[Mr. Foxen]

[quote name='4 Strings' post='1010193' date='Nov 2 2010, 11:27 PM']Can a small cab do it?[/quote]

According to Hoffman's Iron law, a small cab can do it, but you'll need lots of power. The Acme cabs go for that compromise, they go very low, but need loads of power. The cab volume (of air inside) is the important factor. They use small speakers for midrange and high frequencies, in addition to large woofers.

[Bill Fitzmaurice]

[quote name='4 Strings' post='1010352' date='Nov 3 2010, 04:26 AM']I wonder if this is the same here, smaller boxes can mimic with ever increasing accuracy but there's no substitute for volume. Even if small cones can be made to work a lot of them will be needed.[/quote]The performance triad is cabinet size, sensitivity and low frequency extension. Any one or two may be compensated for by alteration of the remaining. If one desires a small cab that goes low the odd man out is sensitivity, which may be compensated for by higher power input. But that requires a driver capable of making use of said power, and an amp capable of delivering it. Both of those can add considerable cost. The least expensive solution comes with a larger driver(s) and larger cab, but then you need the means to carry it to the gig. What remains a constant is that there's no such thing as a free lunch.

[4 Strings]

Rather than be left hungry I chose a transport problem!

I think what I was really asking was whether the triad rule is true along each branch, ie despite sacrificing sensitivity do you get that same depth with a small cab as you do if you sacrifice size?

Sensitivity is not such an issue nowadays with power coming cheap, so this would seem a good compromise (and one of which I would love to take advantage but they are so expensive!) but do you get such a deep and powerful tone?

[Bill Fitzmaurice]

[quote name='4 Strings' post='1011103' date='Nov 3 2010, 01:26 PM']Sensitivity is not such an issue nowadays with power coming cheap, so this would seem a good compromise (and one of which I would love to take advantage but they are so expensive!) but do you get such a deep and powerful tone?[/quote]Power is cheap. Drivers that can make use of it, not so much. And that doesn't mean watt ratings, which are next to worthless. It has to do with excursion, and the usual sources do not use high excursion drivers.

[LawrenceH]

[quote name='4 Strings' post='1011103' date='Nov 3 2010, 05:26 PM']Rather than be left hungry I chose a transport problem!

I think what I was really asking was whether the triad rule is true along each branch, ie despite sacrificing sensitivity do you get that same depth with a small cab as you do if you sacrifice size?

Sensitivity is not such an issue nowadays with power coming cheap, so this would seem a good compromise (and one of which I would love to take advantage but they are so expensive!) but do you get such a deep and powerful tone?[/quote]

You're still constrained by the mechanical limitations of the cone and voicecoil design. So while you can theoretically throw more power at it to compensate I doubt there is a 10" driver in the world capable of taking anything like the power you'd need to match an 18" cab. It would probably be in the order of thousands of watts and require an enormous displacement.

Having said that, the lunch isn't free but since as pointed out power is so small and light these days, the lunch is getting a lot cheaper. Bill, Alex and the like are often pointing out that there is no 'sound' inherent to a 10" versus a 12" driver (other than loss of HF and greater beaming as you get bigger) but in reality, I think many cabs on the market will exhibit a trend as most manufacturers prefer to deal with the compromises of a particular driver size the same way. The Acme cabs mentioned seem to be the honourable exception, I'd love to give one a try.

[markstuk]

"but I remember asking a glider pilot friend of mine whether new technology is reducing the span of glider wings, he responded this was kind of true but there's no substitute for span."

Apart from Talent :-) (I'm a gliding instructor)

Glider wings are long and thin (high aspect ratio) because for a given area this form factor produces the least total (form + induced) drag in the speed ranges gliders typically fly at.. So if anything we're using new materials (carbon fibre/kevlar) to make longer/thinner wings than we used to (subject to class/racing limitations in standard/15 metre class (both of these amusingly if confusingly comprising of gliders limited to 15m wingspans), 18 metre and "Open class" . As we approach 30 metres the penalty paid in handling/adverse yaw drag to date has proven to apply a practical limit.

Any inprovements in aerofoil design/airflow management can be generally applied just as well to long wings as short wings, and the competition classing system (think yacht classes) means that there is no sporting benefit in having shorter wings than your compeition.. The only exceptions are open class aerobatic gliders but this a very fringe activity occupied by pilots with more money than sense .. On a pound per minute basis it's cheaper to run an Extra 300 than indulge in glider aerobatics....

cheers


Mark

[4 Strings]

[quote name='markstuk' date='Nov 3 2010, 06:52 PM' post='1011207']
"but I remember asking a glider pilot friend of mine whether new technology is reducing the span of glider wings, he responded this was kind of true but there's no substitute for span."

Apart from Talent :-) (I'm a gliding instructor)

Glider wings are long and thin (high aspect ratio) because for a given area this form factor produces the least total (form + induced) drag in the speed ranges gliders typically fly at.. So if anything we're using new materials (carbon fibre/kevlar) to make longer/thinner wings than we used to (subject to class/racing limitations in standard/15 metre class (both of these amusingly if confusingly comprising of gliders limited to 15m wingspans), 18 metre and "Open class" . As we approach 30 metres the penalty paid in handling/adverse yaw drag to date has proven to apply a practical limit.

Any inprovements in aerofoil design/airflow management can be generally applied just as well to long wings as short wings, and the competition classing system (think yacht classes) means that there is no sporting benefit in having shorter wings than your compeition.. The only exceptions are open class aerobatic gliders but this a very fringe activity occupied by pilots with more money than sense .. On a pound per minute basis it's cheaper to run an Extra 300 than indulge in glider aerobatics....




Erm, so are they louder?

[Phil Starr]

Sorry I can't resist a good nerdy thread. There isn't a single solution to the problems posed by speaker design. All designs are necessarily compromises. Even a 10" speaker doesn't go high enough in its piston region to successfully reproduce the upper harmonics necessary for a decent sounding bass guitar and just about every instrument speaker I have seen is operating under cone breakup to reproduce the upper frequencies. Since most of the character and perceived 'loudness' of a bass speaker are all about what goes on in the midrange how a speaker behaves under breakup is pretty important.

Even at the bass end size is only one factor. To go deep you need heavy cones but this lowers efficiency because you have to accelerate a bigger mass. The volume of air you shift is important and you can make a smaller cone shift a lot of air if you make a speaker with a good excursion (Xmax) but this means a long voice coil which lowers efficiency. It also lowers the damping of the speaker and affects transient response. Very little of the speakers energy actually makes any sound. Most instrument speakers are between 1% and 4% efficient, The big problem is that the air in front of the speaker presents a very low impedance to the speaker. Bigger cone areas increase the efficiency of this coupling of speaker to air as do horn enclosures like BFM's but to work properly a horn needs to be vast (16 feet across for low B!). So all things being equal a bigger cone area will give louder bass than a small cone and you can't completely compensate with a bigger excursion. You can compensate with multiple drivers or a horn cab but these bring other problems.

I love the uncertainty. There are so many ways of solving the problems of speaker design and each only opens up other problems and compromises. Anyone who tells you they have the answer is kidding themselves, the only test that matters with an instrument speaker is do you lke the sound? The science will get you 2/3rds of the way there but there is still no substitute for a listening test.

[4 Strings]

It sounds monsterous!

Hence my original question. I was already very impressed with the 2x10, which has a deep cabinet and ducted porting and gives plenty of bass (have even rolled it off slightly on the amp at some gigs), but anything not linked to the 'Monster' now sounds tinny.

[51m0n]

[quote name='LawrenceH' post='1011181' date='Nov 3 2010, 06:31 PM']You're still constrained by the mechanical limitations of the cone and voicecoil design. So while you can theoretically throw more power at it to compensate I doubt there is a 10" driver in the world capable of taking anything like the power you'd need to match an 18" cab. It would probably be in the order of thousands of watts and require an enormous displacement.[/quote]

Its surprising though. Forgive me for keeping this simple and looking at the area of the circle rather than the cone (since we dont know the depth of the drivers), but an 18" driver has an area about 3.25 times greater than a 10" driver <just put
(pi * (9^2)) / (pi * (5^2)) in to google>

So if the 10" driver had an excursion limit more than 3.25 times the excursion limit of the 18" driver then they are pretty evenly matched.

Given the ropey nature of most old 80's drivers, and a lot of 90's drivers I can well believe that that is either achievable now, or will very soon be.

If you move up to a 12" driver then you are looking ar only 2.25 * the excursion....

We all know that current voice coils can take significantly more that 2 or 3 times the thermal energy of older voice coils too.

Edited November 4, 2010 by 51m0n

[JPJ]

I'm fascinated by threads like this one. Main stream equipment suppliers seem to ignore Hoffman's Iron Law and I'm guessing that both my cabinet setups must be hugely compromised in order to produce what I consider to be a very musical sound.

Recent point in fact, a band I dep with occassionally use a Mackie PA rig. They normally use the 1802 (2x18 powered bin) for the bottom end but have recently bought a Thump bass bin (1x18). Now whereas the 2x18 bin is an awkward 2 man lift, the Thump can be carried by one person and is only slightly larger than the 18" driver. Ok, it doesnt kick the bass out like the 2x18, but it does add a lovely warm tone to the rig, is bloody loud to my ears, and is ideal in smaller 'pub' type venues.

Am I right in assuming that the Thump is compromised and is making up for it with sheer power (1000w 'rating')?

[Mr. Foxen]

[quote name='JPJ' post='1011766' date='Nov 4 2010, 10:16 AM']I'm fascinated by threads like this one. Main stream equipment suppliers seem to ignore Hoffman's Iron Law and I'm guessing that both my cabinet setups must be hugely compromised in order to produce what I consider to be a very musical sound.

Recent point in fact, a band I dep with occassionally use a Mackie PA rig. They normally use the 1802 (2x18 powered bin) for the bottom end but have recently bought a Thump bass bin (1x18). Now whereas the 2x18 bin is an awkward 2 man lift, the Thump can be carried by one person and is only slightly larger than the 18" driver. Ok, it doesnt kick the bass out like the 2x18, but it does add a lovely warm tone to the rig, is bloody loud to my ears, and is ideal in smaller 'pub' type venues.

Am I right in assuming that the Thump is compromised and is making up for it with sheer power (1000w 'rating')?[/quote]

The main stream compromise is usually 'Low', proper low end isn't really heard by your ears so well, so they can get away with making it sound quite loud in the still bassy but not as power hungry area.

[markstuk]

No, they're quieter (except when I'm screaming at the competition :-) )

"Erm, so are they louder?"

[Bill Fitzmaurice]

[quote name='JPJ' post='1011766' date='Nov 4 2010, 06:16 AM']Main stream equipment suppliers seem to ignore Hoffman's Iron Law

Am I right in assuming that the Thump is compromised and is making up for it with sheer power (1000w 'rating')?[/quote]
The Thump is compromised, and the 1000w rating is 'peak', not RMS. With an F3 of 50Hz it doesn't even qualify as a true subwoofer, that being the result of a cab that's too small to go both loud and low. Hoffman will not be denied.
With a premium long excursion driver one can use high power to overcome the limitations of size. But the Thump isn't loaded with a premium long excursion driver, and 500 watts RMS isn't high power where subs are concerned. Not that it doesn't serve well enough considering its size and price, but it hardly lives up to its overblown advertising. To be fair, though, not much does.

Edited November 4, 2010 by Bill Fitzmaurice

[4 Strings]

[quote name='51m0n' post='1011732' date='Nov 4 2010, 09:50 AM']Its surprising though. Forgive me for keeping this simple and looking at the area of the circle rather than the cone (since we dont know the depth of the drivers), but an 18" driver has an area about 3.25 times greater than a 10" driver <just put
(pi * (9^2)) / (pi * (5^2)) in to google>

So if the 10" driver had an excursion limit more than 3.25 times the excursion limit of the 18" driver then they are pretty evenly matched.

Given the ropey nature of most old 80's drivers, and a lot of 90's drivers I can well believe that that is either achievable now, or will very soon be.

If you move up to a 12" driver then you are looking ar only 2.25 * the excursion....

We all know that current voice coils can take significantly more that 2 or 3 times the thermal energy of older voice coils too.[/quote]


The speaker in the Monster cab has a 75mm (3") voice coil excursion. That seems huge to me, if one imagines the cone moving 32mm each way. I can't see a 10" speaker having a greater excursion than that, it would have to have a telescopic surround material!

I have walloped it up loud and while the 10s in the top cab were clearly waving about, the big fella seemed to be hardly moving. Goodness knows what you have to do to get it to reach its excursion limits. Sounded great though!

[Bill Fitzmaurice]

[quote name='4 Strings' post='1012207' date='Nov 4 2010, 11:53 AM']That seems huge to me, if one imagines the cone moving 32mm each way.[/quote]It doesn't. The voice coil diameter is 3 inches. Excursion is probably in the vicinity of 4 to 6mm.

[LawrenceH]

[quote name='51m0n' post='1011732' date='Nov 4 2010, 09:50 AM']So if the 10" driver had an excursion limit more than 3.25 times the excursion limit of the 18" driver then they are pretty evenly matched.

Given the ropey nature of most old 80's drivers, and a lot of 90's drivers I can well believe that that is either achievable now, or will very soon be.[/quote]

I think a good 10" now might beat a bad 18" from back in the day, but not a good one - not by that much at least. Highest excursion specs I've seen on any PA 10" woofer are about 5mm xmax (though this depends on measuring method). Plus a modern 18" will have all the same technological advantages as the 10". If we assume Bill's conservative estimate of 4mm for the Monster, you're looking at 13mm! I'd be amazed if any 10" drivers could do that with anything like a reasonable sensitivity - and thermal power handling of 10" PA drivers seems to be capped around 250-300 watts. A set of four 10"s, though and you're laughing

[4 Strings]

[quote name='Bill Fitzmaurice' post='1012263' date='Nov 4 2010, 04:23 PM']It doesn't. The voice coil diameter is 3 inches. Excursion is probably in the vicinity of 4 to 6mm.[/quote]


Thanks, I'm sure you're right and I read it wrong, its described as a 'Long excursion 3" coil'. No wonder I could get it to go anything like 75mm!

In fact here's the spec, although it doesn't tell you much apart from it not being terribly efficient and darn heavy:

[i] 18" Hartke High Powered Driver with Long Excursion 3" coil.
120 oz. Magnet
Heavy duty casters with and additional top handle for tilt back wheeling.
4 Airflow curved vents for superior low end.
Highly dampened cabinet and substantial internal bracing
Inputs: 1/4" and Speakon connectors
Impedance: 4 ohms
Power Handling: 400 watts
SPL: 96 db / w / 2v
Frequency Response: 28-300hz
Dimensions: 30.75" (h) x 24" (w) x 18" (d)
Weight: 94 lbs[/i]

[4 Strings]

[quote name='LawrenceH' post='1012299' date='Nov 4 2010, 05:03 PM']I think a good 10" now might beat a bad 18" from back in the day, but not a good one - not by that much at least. Highest excursion specs I've seen on any PA 10" woofer are about 5mm xmax (though this depends on measuring method). Plus a modern 18" will have all the same technological advantages as the 10". If we assume Bill's conservative estimate of 4mm for the Monster, you're looking at 13mm! I'd be amazed if any 10" drivers could do that with anything like a reasonable sensitivity - and thermal power handling of 10" PA drivers seems to be capped around 250-300 watts. A set of four 10"s, though and you're laughing[/quote]


Difficult to do an A/B for 18" vs four 10"s as they are usually designed to do different jobs. I have a wonderful Trace 4x10, which has a very deep cabinet but it doesn't seem to go as deep in bass as the Hartke 2x10, nor anything like the Monster. (I had a Trace 1518 (15") years ago and that did. It was wonderful, I long for the days when I used to gig with that lot!)

I'm sure the A/B could be set up and show a favourable comparison with suitably designed speakers and cabinets but I can't help think that the 10s will be trying hard to do what a speaker like the Monster does with ease.

Lastly, where does the 13mm you mention come from?