Bill Fitzmaurice

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[quote name='Musicman20' post='622008' date='Oct 9 2009, 03:44 PM']I know it applies more to their guitar cabinets, but the Orange cabinets are made from 13 ply high density 18mm birch plywood. Is this an example of fast labour?[/quote] Probably. 18mm Birch does make a nice cab, and requires minimal bracing, so it's a fast and easy build, giving a good result with minimum labor costs. With adequate bracing 12mm birch can give just as good a result, with a lot less weight, albeit with higher build costs. If you price out 12mm versus 18mm you'll find not that much difference, not nearly enough for the materials savings realized using 12mm to come close to compensating for the additional labor that material demands for an equal result. Ask any structural engineer the best way to build anything to realize maximum structural integrity, stiffness and strength to weight ratio and they'll always reply [i]with minimal material thickness and maximum surface to surface bracing[/i]. An aircraft or boat serve as good examples of lightweight high strength construction. A Centurion tank is certainly strong enough, but it will neither float nor fly.

[quote name='stevie' post='621899' date='Oct 9 2009, 01:30 PM']His explanation about how stuffing works may be incorrect (although I think if you slag off Richard Small the least you could do is provide some supporting references) but the practical consequences of stuffing a sealed box are the same – you increase the effective box size! Call it increasing the compliance of the enclosure or lowering the system Q - these are both things that happen when you increase the size of the box.[/quote]When stuffing is used to achieve a lower Q overall system sensitivity and extension will be minimally altered, if at all. When a larger box is used system sensitivity will go up and extension will go lower. Using stuffing to lower Q can mimic the flatter response of a larger box, but it won't give the greater sensitivity and lower extension of a larger box.

[quote name='Balcro' post='621785' date='Oct 9 2009, 11:44 AM']Could the manufacturers also do this to deliberately give the speakers a rougher sounding edge? Balcro.[/quote]One could make that case, but the more likely explanation is that they don't want to add to the build cost of the cab by properly lining it. They'd feel quite safe in so doing based on the facts that most users aren't aware that the cab should be lined, and those who do aren't likely to examine the inside of the cab before buying one.

[quote name='stevie' post='621765' date='Oct 9 2009, 11:17 AM']Mr Small ([i]the[/i] Mr Small) disagrees. In fact, he disagreed in 1972 in his AES paper called "Closed-Box Loudspeaker Systems" when he said: "Many closed boxes contain filling material which helps to damp standing waves within the enclosure at frequencies in the upper piston range and higher. If the filling material is chosen for low density but high specific heat, the air compression inside the enclosure tends to be partly or completely altered from adiabatic to isothermal. This increases the effective compliance of the enclosure, which is equivalent to increasing the size of the unfilled enclosure. The maximum theoretical increase in compliance is 40%, but using practical materials the actual increase is probably never more than about 25%. An ancillary effect is an increase in the total moving mass of the system. Depending on the initial diaphragm mass and the conditions of filling, the mass increase may vary from negligible proportions to as much as 20%" It doesn't apply to a ported cab, though.[/quote]Mr. Small disagreed in 1972. In the intervening three plus decades the above explanation of how stuffing works has been found to be incorrect. As recently as three years ago the esteemed Vance Dickason's 'Loudspeaker Design Cookbook' still espoused this debunked theory, but in the latest edition he too has come on board with what is now recognized by the AES as to the true function of stuffing. How stuffing affects the cabinet Q and impedance can be clearly and easily seen with current loudspeaker modeling software; the accuracy of the software has been confirmed with actual measured results.

[quote name='Mr. Foxen' post='621597' date='Oct 9 2009, 08:50 AM']Does packing the cab with stuff (not just covering the walls) lower the speed of sound and make the cab respond as if it is slightly larger also?[/quote]No. Packing a sealed cab will lower the box Q to tame a midbass peak. Contrary to popular belief it will not give the same result as a larger box. Ported cabs should be fully lined, to no more than a 2" thickness, but not stuffed.

[quote name='OmeDunk' post='621633' date='Oct 9 2009, 09:16 AM']That wouldn't be easy, since I live in The Netherlands. Are there any other options?[/quote] Ask on my forum, we have members in the Netherlands.

[quote name='Ray' post='621295' date='Oct 9 2009, 03:54 AM']I've never known a bass cab to have foam inside.[/quote]Cabs that you may have seen without damping should be considered defective. There are two reasons for not fully lining a cabinet. One is that the manufacturer doesn't know any better, the other is that the manufacturer does know better but prefers not to go to the expense.

[quote name='fenderiko' post='620942' date='Oct 8 2009, 03:08 PM']so why making the cab heavy ? [/quote]Because it's cheaper. Many cab manufacturers make a big deal about using 3/4" plywood, as if that's a good thing. It's not. Manufacturers use 3/4" plywood because it will give an adequate result with minimal bracing and can be assembled by unskilled minimum wage help in less than two hours from start to finish. A properly braced cab made from 1/2" plywood will be significantly lighter than a cab made from 3/4", yet it will have the rigidity of a cab made from 1". But build time will be roughly doubled, as will the number of parts in inventory, so with the overwhelming majority of manufacturers that's not how it's done.

[quote name='Mr. Foxen' post='620822' date='Oct 8 2009, 01:07 PM']Labour intensive and don't lend themselves to mass manufacture.[/quote]What they don't lend themselves to is high profit margins.

[quote name='Monz' post='620452' date='Oct 8 2009, 07:21 AM']when you get to LOUD levels the lightweights seem to loose the ability to punch the sound forward and in the case of the ultra lightweights seem to vibrate rather violently[/quote]There's a right way to build light weight cabs, which when employed will vibrate less than heavy cabs while sounding better, and there's a wrong way. One guess which applies to the lightweights you tried.

[quote name='fenderiko' post='620191' date='Oct 7 2009, 08:22 PM']why designing them so heavy in the first place ? surely people rather not lift more weight ? ? what is making then so heavy ? the wood ? driver ?[/quote] Older drivers with ceramic magnets can weigh two to four times what newer neo magnet drivers weigh. Cabs made of cheap particle board or MDF will be heavier than those made of plywood. Well braced cabs made of 12mm plywood will weigh less than poorly braced cabs made of 18mm plywood. Birch is heavier than Poplar. There are many reasons why some cabs are light and some weigh a ton. But weight alone isn't an accurate predictor of how any speaker will sound.

[quote name='muzzer' post='619506' date='Oct 7 2009, 07:52 AM']Anyway, I have done some asking around locally and there is a furniture restorer close to me who will apparently do cabinet work so I'll give hime a go.[/quote] Insist that he follow the instructions to a T, including the choice of materials and adhesives.

[quote name='alexclaber' post='618703' date='Oct 6 2009, 10:59 AM']When you cut the lows on a bass amp it's akin to cutting the gain, i.e. turning the amp down, because most of the power demands for bass guitar are in the lows. Alex[/quote]And to paraphrase Mr. Franklin a watt saved is a watt gained.

[quote name='argle' post='617964' date='Oct 5 2009, 04:07 PM']It can still sound a bit woolly at the low-end, though, presumably just by virtue of it being short-scale.[/quote] I build my own basses, and over the years transitioned to a 30" scale, as I have small hands and it's more comfortable. There's virtually no difference in the tone of my basses with 30", 32" and 34" scales.

[quote name='alexclaber' post='618581' date='Oct 6 2009, 09:20 AM']Actually you'd be less likely to clip anywhere along the signal chain if you left the 1x18" ported, plus the 18" would be less likely to run out of excursion. Alex[/quote]+1. With the added low frequency sensitivity gained by porting the 18 and the bass EQ cut more headroom is gained. The idea that flat EQ settings are of any value is intrinsically flawed, since neither amps nor speakers have flat response to begin with. The purpose of EQ knobs isn't to have them all pointed to 12:00, it's to have them set wherever they give the best result. If you can get the tone you want with the bass EQ cut by 3dB that's the equivalent of doubling the usable power from your head.

[quote name='benwhiteuk' post='617425' date='Oct 5 2009, 08:58 AM']With a poorly designed rear-ported cab there is the possibility for slight cancellation, which basically means it's gonna have a lower SPL within a certain frequency range than a front ported equivalent.[/quote]That would require that the distance from the cone on the front of the cab to the port opening on the rear of the cab be 1/2 wavelength at the cab resonant frequency. As that amounts to some 8 to 10 feet it's not a major consideration.

[quote name='waynepunkdude' post='616995' date='Oct 4 2009, 06:09 PM']I will give it a go, cheers buddy. Can I just be clear, do you mean set the left knob to about 4 o clock?[/quote]Yes, and look at the manual regarding setting the rear panel switches and running a patch cable to run Full Range/Lows.

[quote name='waynepunkdude' post='616810' date='Oct 4 2009, 03:21 PM']So will changing the fequency on the cross-over to put more of the load onto the 4X10 help?[/quote]The cabs you have aren't designed for true bi-amping. You should be running the 4x10 full range, the 1x15 lows only with the low pass filter set around 800 Hz.

[quote name='Alien' post='616584' date='Oct 4 2009, 11:27 AM']You could try lowering the crossover frequency, which would have the effect of making the 4x10 do more of the work. The biggest problem with using a standard 1x15 (or pretty much any bass cab really) as the low end in a biamped rig is that they're not really designed for it. What you need is a sub of some kind - a PA sub would do fine. A[/quote] I just assumed he was running both cabs full range. There's no point to bi-amping these speakers, though running stereo does offer the advantage of being able to power shade.

[quote name='Mr. Foxen' post='616184' date='Oct 3 2009, 10:19 PM']The watts bit is kind of irrelvant if it is your amp lighting up. Its if you are cranking the 15 side because theres not enough volume from the 15, that you need a second 15. Guessing you are running the classic 1x15 and 4x10. Probably the 4x10 is more efficient all round, so you are getting plenty from that, but the 15 is struggling to keep up.[/quote]You're quite correct. The 'classic' 1x15/4x10 is a poor match up, not just because the 1x15 handles less power but also because it has less sensitivity than a 4x10. A 1x15 works OK with a 2x10; to keep up with a 4x10 you either need a 2x15 or another 4x10.

[quote name='waynepunkdude' post='616115' date='Oct 3 2009, 06:07 PM']All the manual has is this.[/quote] That shows separate limiters for each power amp. How they function should be explained in the manual. If it isn't a conversation should be held with the amp manufacturer as to why not.

[quote name='waynepunkdude' post='616095' date='Oct 3 2009, 05:06 PM']Could it be possible that the limiter is only kicking in for one side?[/quote]That depends on how it's configured. The owner's manual should say.

[quote name='waynepunkdude' post='616064' date='Oct 3 2009, 04:18 PM']Oh the specs of my amp are: OUTPUT POWER RATING 1350 Watts Mono-Bridged @ 4 Ohms (1000 Watts Continuous) 840 Watts Mono-Bridged @ 8 Ohms (680 Watts Continuous) 2 x 675 Watts @ 2 Ohms (500 Watts Continuous) 2 x 420 Watts @ 4 Ohms (340 Watts Continuous) 2 x 255 Watts @ 8 Ohms (205 Watts Continuous) I use both power amps at 8OHMS (1 cab per power amp) my cabs are 300W & 600W[/quote] If you're lighting up the limiter it means you've reached the extent of the clean rated power of the amp. If that's not loud enough chances are your speakers are insufficient for the job, no matter what they're rated, and sending even more power to them probably will lead to a less than desirable result.

[quote name='waynepunkdude' post='616027' date='Oct 3 2009, 03:14 PM']My limiter light keeps on coming on, what will happen if I press the limit defeat button?[/quote] The light won't come on. And of course the limiter won't be functional, which increases the possibility of damaging your speakers.