Bill Fitzmaurice

[quote name='Mr. Foxen' post='590205' date='Sep 4 2009, 05:24 PM']Course, not everywhere has a PA, and much more often, the PA can't cope with bass. Not sure if America is like those places in Europe where you can get a grant and everywhere has great PA systems, but this idea that the PA will do it all seems to be fantasy in practice.[/quote] The situation here is that toilet gigs that pay crap expect you to supply your own PA, and if you don't have one you don't work. Which makes sense, if they had the money to pay well they'd have the money to install a PA. Good gigs pay well and provide PA. The better the gig, the better the PA. Either way, if you're going to sound good you need a good PA, either the house's or your own.

[quote name='KingPrawn' post='590120' date='Sep 4 2009, 03:17 PM']This may indeed sound very stupid, but it has never stopped me before. Is there a calculation for working out how loud your rig needs to be. eg style of music x venue X punters = Watts. Again i apologise for daft questions , but is is better to buy for example an ampeg head that is 450w or a lesser head that is 900w. Does the quality of build come into it?[/quote] No, for three reasons. First, watts and sound levels aren't directly related. Second, all else being equal twice the power only results in a 3dB increase in sound level, and that's just above the threshold of audibility. Third, and most important, your rig only needs to be loud enough to cover the stage. It's the job of the PA to cover the room. If you're trying to handle much more than a hundred seats or so without PA support you're probably going to sound bad and have stage levels loud enough to endanger your hearing.

[quote name='alexclaber' post='581432' date='Aug 26 2009, 09:39 AM']Wasn't it the famously hopeless BL years actually? Alex[/quote]Let's not forget about Lucas Lighting and the joys of positive grounding. In my college years one bought an MGB or Midget, or a Sprite, in the hopes that the coolness of the ride would get one laid. The time spent trying to keep the damn things running was so all encompassing that any all other extracurricular activities, including a decent nights sleep, were relegated secondary status at best.

[quote name='karlfer' post='579983' date='Aug 25 2009, 06:02 AM']Anybody using any of the Chinese stuff?[/quote]There's precious little that's not sourced from Asia, if not as a finished good then as the components within. BTW, neither quality nor lack of it is defined by national origin. I remember when, if you considered a certain brand of automobile, you were encouraged to buy them in pairs, giving you one to drive whilst the other was in the shop. The brand was Jaguar.

[quote name='alexclaber' post='581114' date='Aug 26 2009, 05:48 AM']"High-quality" being the critical phrase! Alex[/quote]That depends on your definition of high quality, which IMO isn't far off from high fidelity. As with a hi-fi speaker a good PA speaker puts out pretty much the same sound as the source, with minimal coloration of its own. At the opposite end of the spectrum are guitar cabs, which are as colored as it gets, the tone being virtuallly defined by the speaker. Some electric bass cabs are so highly colored that it doesn't matter what you have for an instrument or amp, everything sounds pretty much the same through them. Some, though very few, electric bass cabs are uncolored, allowing the tone of the instrument and amp to come through. Most lie somewhere in between. For the most part the degree of coloration is inversely proportion to the cab's level of engineering and cost, though some very expensive cabs are highly colored and poorly engineered, which IMO makes them low quality irrespective of their price. If you prefer a cab that's highly colored there's certainly nothing wrong with that, beauty does lie in the ears of the beholder. My preference is for cabs that allow me to get the tone that I want, not just that tone that they're capable of delivering. For those with a similar bent trying PA cabs to see how they work for them is a more than worthwhile exercise.

[quote name='warwickhunt' post='580791' date='Aug 25 2009, 06:13 PM']why, at less than £100 a piece, wouldn't they make stonking bass cabs and why don't more people utilise used PA cabs as bass cabs?[/quote]Because the average bass player is under the wrongful assumption that 'electric bass' cabs are somehow better suited to the needs of electric bass. The very highest frequencies aside the needs of high quality PA and high quality bass are the same.

[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.