Bill Fitzmaurice

[quote name='escholl' post='575906' date='Aug 20 2009, 01:34 PM']as mentioned, it's just part of the tweeter protection and is nothing to worry about. you amp is fine. :][/quote] Yes it is the tweeter lamp lighting up and yes, you should be concerned, as that lamp only lights up when there's excess high frequency input to the tweeter that could harm it, or the lamp, or both. I wouldn't panic, but I'd refrain from doing whatever you were doing that made it so angry.

[quote name='alexclaber' post='569164' date='Aug 14 2009, 10:54 AM']The problem is that anyone with experience of those other drivers won't have experience of them in the Jack 12, and that's the only kind of experience that counts. Based on my knowledge of Bill's other mid-horn designs you'll need a rising response in the midrange to compensate for the lowpass nature of the horn. Alex[/quote]There's an open thread on my forum right now from someone in the UK who built OTop 12s using drivers that were not recommended, but because someone on another forum said they were OK he used them anyway. The cabs don't work right. I have a support forum specifically to help builders avoid such mistakes. Ignore it at your own peril.

[quote name='alexclaber' post='568893' date='Aug 14 2009, 07:14 AM']Well if you will insist on using such a spectacularly wimpy amp... Alex[/quote]Between the infirmities of age and my Scot blood that won't allow me to pay more than I have to the Superfly meets my requirements for weight and price. Since my speakers have the requisite sensitivity to give me the output I want 'tis hardly problematic. But I'm hardly the only person with less than a kilowatt at my disposal, and this does bring up a valid point about long excursion high power single woofer cabs: while they may have the potential to have output equal to larger multiple woofer cabs, they'll only do so with adequate power. Potential purchasers of said speakers who don't have better than 200 watts or so may find that, unless they want to get a new amp, they may be better off with the higher sensitivity offered by dual woofer cabs.

[quote name='alexclaber' post='568439' date='Aug 13 2009, 04:40 PM']So Bill's previous assertion that a Jack 12 will beat a fEarful 12/6 or 15/6 hands down is hyperbole. If you have the power the fEarfuls are more than competitive. Alex[/quote]'If' being the operative word. I run a Superfly myself, and with it I have to run two cabs the equivalent of fEarful 12/6 (3012 HO/ Celestion NTR06-1705B loaded) to deliver as much clean output as one 2512 loaded J112. [quote]Although a midrange horn does increase the midrange sensitivity and improve the off-axis response, it adds colouration which may not be desired and increases cab size for equal LF sensitivity. It also has no benefit for excursion limited power handling which is the usual limiting factor in bass cab output.[/quote] The acoustic loading of even a short horn does increase excursion limited power, and low frequency sensitivity as well. I tested my J112 side by side with a reflex loaded box of exactly the same size, loaded with the same driver. The J112 beat the reflex across the board save around 1kHz. You do have to give up something somewhere to gain it somewhere else.

Be it used or new buy the best quality head you can afford, so as not to outgrow it in short order. Probably the most versatile cab configuration is the 2x10. One will cover the smaller gigs, two just about anything. 8 ohm 2x10 is the best option, so that you may run two with almost any amp, and as many as four with some.

[quote name='deksawyer' post='567997' date='Aug 13 2009, 09:30 AM']I have a pair of B&C 12HPL64 12" Neo drivers, 4 ohm though. Yours for £150/pair inc. shipping. Same as these but 4 ohm; [url="http://www.bluearan.co.uk/index.php?id=BAC12HPL64&browsemode=manufacturer"]http://www.bluearan.co.uk/index.php?id=BAC...de=manufacturer[/url] D.[/quote] As with all my designs the J112 requires not only specific T/S specs but also specific driver response. You should be posting your question at [url="http://billfitzmaurice.net/phpBB3/"]http://billfitzmaurice.net/phpBB3/[/url], with links to the driver data sheets showing the manufacturer's axial response charts.

[quote name='Mr. Foxen' post='567269' date='Aug 12 2009, 03:14 PM']Bill almost never elabourates on why he's right, only on why someone else is wrong. I don't think it is in his business interests to do otherwise. When pressed, Claber will write a huge essay that takes several reads to understand. I prefer the latter approach.[/quote] If you want to look into this further there are many sources available. Try Dr. Earl Geddes for one. My personal philosophy regarding posts on forums is that anything worth saying is worth summarizing in a few concise paragraphs, if not a few concise sentences. If you want to be bored to tears read an AES Preprint. My job requires that I read every one when they appear, so I have to suffer through them. Your's doesn't.

[quote name='alexclaber' post='567010' date='Aug 12 2009, 12:29 PM']All the evidence suggests that the group delay of a well designed ported cab is inaudible.[/quote] +1. Group delay is inaudible in the non-directional frequencies, for the same reason that they are non-directional.

[quote name='Badass' post='565953' date='Aug 11 2009, 10:00 AM']I will see if it changes in different spaces.[/quote] It will. This explains why: [url="http://www.padrick.net/LiveSound/CancellationMode.htm"]http://www.padrick.net/LiveSound/CancellationMode.htm[/url]

[quote name='Badass' post='565930' date='Aug 11 2009, 09:32 AM']Think this is on topic... Is this why my small 1x10 practice combo sometimes sounds like the bottom 'E' blooms, for want of a better word? Almost like it is a little flat and them resolves in a split second. (Ashdown perfect 10 - front ports) Or is that the room, or just poor design of the combo. Just curious. As it doesn't happen with my larger rigs.[/quote] A small 1x10 combo will have very little output at the 40 Hz fundamental, and not a lot at the 80 Hz second harmonic. So in the lower notes you're hearing virtually no fundamental, a bit of second harmonic, and a lot of third harmonic, around 120 Hz. The third harmonic is a bit 'off' from what your ear wants to hear as the dominant, and that probably explains it.

[quote name='SS73' post='565688' date='Aug 11 2009, 04:49 AM']Ok that makes sense, but because the ported cab is producing more sound and moving more air, would this not affect speed.[/quote] No. In both cases the cone will move at the same frequency. If the cone is traveling a longer peak to peak distance the actual speed at which it's moving is faster. This doesn't affect what one might refer to as fast versus slow response. If it did then the volume at which one plays, which also changes the distance the cone moves, would change the response. The primary reason why most commercial vented cabs sound significantly different from sealed is poor cabinet design. They simply put drivers into too small a box, resulting in a boomy midbass. It's possible to produce a vented cab with response indistinguishable from sealed, with none of the shortcomings of a sealed cab.

[quote name='richrips' post='564882' date='Aug 10 2009, 07:53 AM']hi bill, i'm swinging towards your idea for a couple of 1x12+horn jack cabs. before i place my order, a couple of questions: What speakers would this combination use for a good power-weight ratio. i'm quite keen on neo celestions but if you can recommend a 12inch driver,a tweeter and a crossover (or simple plans for one...) available in the uk, i can start doing sums. do you have a response curve for a 1x12 jack cab? Any user feedback on Bills 1x12 jack cabs would also be much appreciated! I'm glad that this is starting to point at a specific build route after all the discussion! Thanks to all the contributors, especially Bill, Mr.T, Alex, Stewart and i'm sure i've missed a few.... Cheers team! rich incidentally, i'm using a peavey 2x10 tvx and a bw 115 both mint condition unlike my back (which i screwed working for removals..) i'll be selling soon from cardiff, plymouth and anywhere in between. also i drive to maidenhead occasionally.[/quote]For specific information regarding my designs you should go to my forum, [url="http://billfitzmaurice.net/phpBB3/"]http://billfitzmaurice.net/phpBB3/[/url]. Thanks.

[quote name='Mr. Foxen' post='564470' date='Aug 9 2009, 04:14 PM']BFM's designs are probably totally awesome and will do what you want, but if you want to save $15 and get something a little more trad looking, go for one of Greenboy's fEarful designs.[/quote]Where basic bass reflex boxes are concerned the fEarful are as good as any commercial offerings, and better than most. I'd be hard pressed to name a commercial cab that's as well engineered, or even close to it for that matter. I've also recently prototyped a couple of 12/6 cabs for a manufacturer, similar to the fEarful 12/6, using the 3012HO driver. They're nice cabs, a lot better than the high priced 'boutique' 1x12s out there. OTOH side by side with my Jack 112 loaded with a only a 2512 they're very much also-rans. You can only do so much with a bass reflex box.

[quote name='richrips' post='564251' date='Aug 9 2009, 12:06 PM']I feel like i should be paying for this much knowledge..... alas, a couple more questions! 1.Is dispersion affected by the width of a cab or simply by the width of the speakers in the cab? (for a traditional box with speaker in front arrangement)[/quote] Both. [quote]2.Why is it bad to use different sized speakers to produce the same frequencies? (surely almost every rig [cue bi-amping argument...] with parallel identical outputs running in to two cabs where one is, say, a 4x10 and the other a 1x15, would be a victim of this fault?[/quote] Because their outputs are different they can detract from each other as much as they augment each other, with a different result at every frequency. Identical drivers/cabs will only augment each other. [quote]SOOOO.... what do i build? Thanks, Rich[/quote]What I said in my first post.

[quote name='Stewart' post='563944' date='Aug 8 2009, 08:04 PM']Take a look at RCF 4PRO 7001 as one example. [url="http://www.rcf.it/web/rcf/products/pro-speaker-systems/4pro-series/4pro-7001a-mh"]RCF 3way arrayable[/url][/quote] Child's play compared to this: [url="http://www.sweetwaveaudio.com/sales/l-acoustics/kudo.php"]http://www.sweetwaveaudio.com/sales/l-acoustics/kudo.php[/url] One could use a Kudo or two for bass, if you've got a mind to, and the price of entry.

[quote name='dood' post='563691' date='Aug 8 2009, 02:42 PM']If drivers of different sizes are in one box and are crossed over correctly, then should they in theory be in a vertical line for best dispersion?[/quote]If you really know what you're doing you put the woofers on either side, the midranges just inboard of them, and the tweeters in the middle. With the proper driver spacing and crossover points you can use this arrangement to deliver very uniform dispersion across the full bandwidth of the cab, and you also can stack multiple cabs vertically for longer throw with no degradation in the quality of the sound. This level of technology is commonplace in the PA world, with prices starting around $4000 per cab, and is as far removed from the typical electric bass cab as a Bentley is from a pair of roller skates.

[quote name='richrips' post='563593' date='Aug 8 2009, 12:39 PM']In the picture below, the speakers are staggered. Does this diagonal arrangement have any advantage/disadvantage over a purely vertical arrangement?[/quote] It's better than horizontally mounted, but not as good as vertical. [quote]Would a diagonally arranged 2x10 on top of a vented 1x12 cab (made possibly using one of bills designs to squeexe every last ounce of low out of it) be a scientifically sound (lol) solution?[/quote]Scientifically speaking never use different size drivers to cover the same bandwidth. Yes, it's seen all the time... for the same reasons that 4x10s are.

[quote name='Mr.T' post='563526' date='Aug 8 2009, 10:29 AM']Forgive my ignorance here.... I thought you said "The wider the source, the narrower the dispertion pattern" ????[/quote]You must also consider the frequency in question. Dispersion is not a static figure, it varies with frequency as well as the size of the radiating source. But your question brings up a good point, that being why high frequency sources are smaller than low frequency sources. One of those reasons is dispersion. The higher the frequency the smaller the source must be or dispersion will be unusably narrow, as in using eighteens for guitar. [quote]coupling output is when the bass makes the floor (or the box it's on) vibrate, causing the floor to generate sound, yes?[/quote]No. Boundary Coupling is when the source is close enough to a boundary to reduce the pi radian size of the space being energized, as in free-space, half-space, quarter- and eighth-space. I wish there was a simple non-technical way to explain it, but there isn't. When a nearby surface sympathetically vibrates it does generate sound, but that's a different scenario entirely.

[quote name='Zach' post='563498' date='Aug 8 2009, 09:40 AM']this may be a stupid question, but would a single 2x10 (or 1x12 in my case) therefore have better dispersal if put vertical on an empty box at chest height, instead of sitting on the floor?[/quote]Yes, though if the front of said box isn't a solid surface you'll lose coupling output above the frequency where the elevation is equal to 1/4 wavelength. With a 3 foot lift that's about 100 Hz. However, 'boom' also occurs in the vicinity of 100-180 Hz, so if you've got a boomy room elevating the cab can help tame it. [quote]and also, since my 112 has a tweeter, which way up is better? tweeter above or below?[/quote] Tweeter above, as tweeters have narrower dispersion than woofers. [quote]it is my honest opinion that two 2x10 cabinets stacked vertically look totally w**k when compared to a 4x10[/quote]Don't think for one moment that the marketeers aren't well aware of your opinion. That's why cabs are made the way they are. If engineers ruled the roost, and didn't particularly care about the source of their next meal, the 4x10 would have gone the way of the Dodo twenty years ago, and with them all the other cabs with horizontally placed drivers. But even engineers have to eat, explaining why so many who do know better continue to build what the market demands, as opposed to what would best suit needs.

[quote name='Mr.T' post='563332' date='Aug 8 2009, 05:01 AM']Can you help me to understand this concept? I can see that having multiple drivers vertically would extend the coverage vertically, but not how having two rows of drivers (traditional 4x10 or 8x10) would then make that coverage horizontally narrower.... am I missing something?[/quote] You've made one of the most common mis-assumptions about how speakers work, which is that they radiate sound in the same fashion that light bulbs radiate light, ie., proportionally to their dimension. The opposite is the case. The wider the source the narrower the dispersion, the higher the source the less the dispersion on the vertical plane. This means that a vertical 4x10 also has half the vertical dispersion as a standard 4x10, which at first glance may seem counter-productive, but it's not. At the distance you're standing relative to the cab getting the upper drivers closer to your ear level still allows you to hear them much better than you can with them down low. At the same time farther away from the cab the narrowed vertical dispersion puts more sound into the audience, where you want it, and less into the floor and ceiling, where you don't. So not only does the vertical array give more uniform audience coverage, it's also louder within the audience for a given amplifier output.

[quote name='lateralus462' post='563256' date='Aug 7 2009, 08:38 PM']but then again at some point someone is going to want to add more speakers - in fact it is fairly usual for someone to want to add, say a 15" cab or another 4 x 10 to their rig -[/quote] Also done on the basis of looks, not utility. The number one deficiency of commercial bass cabs is that they're too small for the drivers contained. One can build a 2x10 with the same low frequency output capability as the average 4x10 by simply making the cab large enough. So why don't manufacturers make cabs as large as they should? Because the average player would think 'it doesn't look right' not stuffing so many drivers into as small a box as possible that it takes a shoehorn and a good load of lubricant to get them to fit. A pair of well engineered 2x10s would deliver all anyone could actually need. [quote]in my opinion any problems with dispersion aren't really a problem in a band enviroment either -[/quote]That depends on how much of the audience you're content to have hearing the same tone that you do. With a 4x10 few will. You can't hear the mids and highs that pass by you at calf level, so you crank them higher. That means the small segment of audience within the cab's 'sweet spot' get nailed with excess mids and highs, while the rest don't hear them even as well as you do. Tilt the cab back and you can hear the mids and highs, but then no one else can. That's one reason why the 8x10 or stacked 4x10 is so popular amongst those who use them, the drivers are high enough so that you and the audience within the sweet spot hear the same thing. A vertical 4x10's/vertically aligned 2x210 sweet spot is literally twice as wide as that of an 8x10 or stacked 4x10s, making it a win/win rig.

[quote name='E sharp' post='563086' date='Aug 7 2009, 04:29 PM']I seem to remember a couple of their cabs being reviewed in Bass Player a few years ago . They picked up on the switch issue (the technicals are a bit beyond me , and I defer to Bill and Alex on this) and Accugroove's reply was a bit snotty . Haven't Epifani come up with a similar silly switch recently ?[/quote] There was a thread on TalkBass exposing the AccuSwitch, it probably set a record there for length. The initial response by A-G was 'we applied for a patent, and won't reveal the specifics until it's granted', which is piffel, since patent protection is retro-active to the date of the application. When the switch's circuitry was revealed and shown to be worthless A-G 'lawyered up' and wasn't heard from on the subject again.

[quote name='Protium' post='563058' date='Aug 7 2009, 03:52 PM']What about a vertical 410? The manufacturers of 4x10's must be doing something right or else no one would buy them...[/quote] Cab manufacturers build what they believe is most likely to sell. What's most likely to sell is what 'looks right'. Unfortunately what please the eyes the most pleases the ears the least, but we are creatures who are dominated by the visual sense. If blind bassplayers had a standard 4x10 and a vertical 4x10 put before them to choose from the vertical 4x10 would win every time. Discriminating sighted players would probably lean towards the vertical 4x10 as well, if they had the option, but the marketeers don't make that option available to them to make the comparison. BTW, said blind bassplayers would also tend to prefer the vertical 4x10 to an 8x10, though not by such a wide margin. That's because to a very large degree what makes an 8x10 sound like an 8x10 is the height of the driver array. Since the vertical 4x10 would be the same height it would share many of the same acoustic properties, though by being narrower it would have even better dispersion.

[quote name='richrips' post='562865' date='Aug 7 2009, 10:49 AM']which 2x10 plans would you recommend?[/quote] None. I only do high sensitivity cabs myself. But if you do go with a standard style 2x10 make absolutely sure you use the driver recommended for it. Choosing a driver and then designing a cab to work with it can be done, but only if you possess a rather high skill level in acoustical engineering. If you don't leave the designing and driver choices to one who does. [quote]But has worked for god knows how many bass players?!! I actually like 4 x 10's as a cabinet, they may not be "correct" but they still sound good![/quote]One might also conclude that a Ford Focus is the epitome of automobile engineering expertise... if one had only a Yugo to compare it to.

Don't build a 4x10. It's the poster child for how a speaker cabinet should not be built. Do a pair of 2x10, stack them with the drivers in a vertical line.