Bill Fitzmaurice

[quote name='Twincam' timestamp='1412795121' post='2572208'] As for the power source a smart move would be to have power from a custom amp head, which would add little to a head. [/quote]The power supply would have to be in the speaker, otherwise you couldn't use them with anything but a dedicated amp. They have their fans, but mainly they're cut from the same cloth as those who yearn for the halcyon days of AM radios and the Model T.

[quote name='Twincam' timestamp='1412770668' post='2571799'] Just a thought but wouldn't field coil speakers be lighter weight and cheap to make and just as powerful as permanent magnet speakers. [/quote]They're more expensive, and overall heavier, as they require a power source. That's why they were replaced by permanent magnets.

[quote name='Graham' timestamp='1412790238' post='2572121'] Unlikely, global neodymium prices have been going down the last couple of years. [/quote]+1. The Chinese, having a corner on the neo market, tried to take advantage of that by price gouging. All that they accomplished was to push the price up enough for other countries to resume mining it, including the US, where it was classified as a strategicly critical material, causing an easing of the restrictions on mining it here. In short, the Chinese shot themselves in the foot. BTW, there's no inherent difference in the sound of neo magnet versus ceramic drivers. Neo magnet drivers may sound different primarily because they are all recent designs, using the latest design techniques, as opposed to ceramic driver designs that may be as much as 40 years old. BTW part II, the major impetus for neo drivers wasn't light weight where finished drivers is concerned. It was for the light weight of the magnets, which are also primarily manufactured in China, be they ceramic or neo. It was the high price of shipping said ceramic magnets to driver manufacturers halfway around the world that first resulted in the popularity of neo. Very little neo by pecentage is used by the loudspeaker industry, most is used in hybrid electric car motors and electric generating windmills.

[quote name='tauzero' timestamp='1412434928' post='2568948'] Being experimentally minded and not having delved into the theory, if I want a note to sound deeper, I play it on a lower string further up the fretboard, and it works. Of course, there's not just the string length to consider, you're also moving the midpoint of the vibrating length of string closer to the pickups, and for that matter, if you don't change your right hand position, you're plucking closer to the midpoint of the vibrating length. [/quote]There's truly deeper, and there's perceived as deeper. The shorter string length will accentuate the harmonics, and as they occur where both speakers and ears work better it will seem deeper. To really appreciate what happens when you play as low as possible on the neck you need speakers that work really well down to 40Hz or so, and most don't. For instance, as a young lad I (and everyone else for that matter) avoided going below A like the plague, as my speakers couldn't handle it and it sounded bad when I ventured down low. When I abandoned store bought speakers for my own creations that were happy playing an open E full tilt I changed the way I play. For instance, playing a typical blues riff in 'C' I don't go up to the third and fifth, I go down, playing them off the F and G on my E string.

You'll see a shift in the fundamental to harmonic ratio as you go up the scale. A vibrating source works best where its dimension is 1/4 wavelength. With an open string 36 inches long 1/4 wavelength is 94Hz. The fundamental of the low B would be stronger if your B string was 1/4 wavelength long, but at 113 inches that would be somewhat impractical. This shift explains why the same notes played at the lower end of the fretboard and the upper end of the fretboard sound slightly different. The shorter string length will have less fundamental content. I avoid playing a note on a lower string fretted above the seventh fret in favor of the same note played on a higher string for this reason. For that matter I avoid going above the seventh fret at all unless I have to. I play bass, not guitar. [quote]I was expecting a succession of even harmonics and not much in the way of odd, but the odd harmonics are there in force.[/quote]That's normal. There is a difference in the ratio of even versus odd harmonics when different classes of amps are pushed to clipping. This in part explains why tube and SS sound different.

The Fly isn't a powerhouse, so it needs a high sensitivity cab. I don't have issues with mine, but only because my cab has very high sensitivity. Most 4x10s have higher sensitivity than most 1x15s, so that's probably the difference you heard.

http://billfitzmaurice.info/forum/viewtopic.php?f=14&t=4140 Suggest you read again the email that accompanied your plans.

[quote name='Jazzjames' timestamp='1411042348' post='2555833'] do speakers become tired and therefore don't respond in the same way as when they were new? [/quote]The driver suspension softens indefinitely with use, but if anything that only enhances the bass response.

[quote name='3below' timestamp='1410893983' post='2554471'] Mr Fitzmaurice's plans work well, the circular saw sled is a really useful bit of kit. You will need plenty of clamps, [/quote]Built as shown in the plans with simple plywood jigs you don't need any clamps. Use them if you have them, but don't worry about it if you don't.

[quote name='Magic Matt' timestamp='1410878581' post='2554208'] The jig would be brilliant if I had a circular saw... but I don't. Also, no power out in the shed, and no safe way to get power out there, hence any power tools I have need to be cordless. [/quote]This is what use, with a good Freud blade: http://www.lowes.com/pd_37452-70-PC18CSL_4294607774__?productId=3478871&Ns=p_product_qty_sales_dollar|1&pl=1&currentURL=%3FNs%3Dp_product_qty_sales_dollar%7C1&facetInfo= This is the way to buy it: http://www.lowes.com/pd_518739-34252-PCCK405N4_0__?productId=50078420&Ntt=power+tool+combo+kits&pl=1&currentURL=%3FNtt%3Dpower%2Btool%2Bcombo%2Bkits&facetInfo=

[quote name='6v6' timestamp='1410853555' post='2553767'] [size=4]I've made a jig like that before, and it does work well provided you happen to have perfectly square leftovers of the right dimensions around, I was just trying to point out that with the tools available to them, the OP is unlikely to do better than a trained operator on an industrial panel saw.[/size] [/quote]All you need is one piece of stock with the factory edge on one side, which becomes the upper piece guide edge. The saw itself cuts the sled base after the two pieces are assembled, giving a perfect zero clearance cutting line. The only other tools required are a screwdriver and drill, as the sled can be screwed to the piece to be cut, the holes filled later. IME most industrial panel saws are lucky to give 4mm dimensional accuracy, with only plus/minus 1 degree tolerance with respect to square. That can result in 1cm of drift on a 60cm cut. I would only trust a merchant to cut raw plywood to 1cm oversized blanks to allow them to be transported home.

[quote name='6v6' timestamp='1410812905' post='2553550'] OTOH if you go to a decent timber merchant they'll be able to cut *far* more accurately than you can with a hand saw [/quote]Not if you make one of these, which will give accuracy of 1mm over a 120cm cut: It doesn't even cost anything, you make it from leftovers from the build material. [quote]The OP only has a cordless jigsaw anyway, which will make getting decent straight cuts for the joints very hard indeed IME. [/quote]+1. A jigsaw is fine for its intended purpose, cutting round shapes. It's not worth squat for straight lines or long cuts.

[quote name='isteen' timestamp='1410640206' post='2551599'] 410 for the punch and power + 115 for the low end and deep bass tones.[/quote]That's the usual reason given, but it doesn't work that way. Fifteens don't go appreciably lower than tens, and even if they did you'd have to use them on a one to one ratio with the tens to equal what the tens are putting out. [quote] I was guessing both cabs would be louder that just the one alone[/quote]Somewhat, if they were both 8 ohm cabs and you could use them together. But they aren't, so you can't.

[quote name='Magic Matt' timestamp='1410621647' post='2551364'] I think there are acoustic issues with running that kind of setup without a cross-over. [/quote]Not really. You use a crossover when one speaker is for lows and one is for highs. Electric bass tens, twelves and fifteens all operate in the same bandwidth, so there's no point in a crossover. For that matter there's no point in using them together either. A fifteen crossed over to a six or eight inch midrange is logical. A 1x15 used with a 4x10 that goes just as low and has more driver cone displacement is illogical.

[quote name='Magic Matt' timestamp='1410522586' post='2550317'] Still tempted to put some small 12mm baton on the inside of the corners... because then I can trim the outer edges with 12mm quadrants and get a really nice look... [/quote]Follow the plans. Even when radiused at 3/8 inch, which is standard for protective corners, the edges of the cab don't require any reinforcement. If they did [i][b]it would be in the plans[/b].[/i]

[quote name='Dad3353' timestamp='1410457166' post='2549689'] Clipping [i]is [/i]DC, alternating between +ve and -ve at a certain frequency. For a period of time, the speaker sees a constant potential, which suddenly reverses polarity. Yes, it's alternating, but just as damaging as DC in the constant polarity sense. Speakers are happy when they're moving. They don't like being pinned up against one end of their travel or the other. [/quote]None of that is true. Read the QSC link that I posted. The author is not only an applications engineer at QSC but also a past Secretary of the AES. Whatever sources you got your information from are simply incorrect.

[quote name='Chienmortbb' timestamp='1410452743' post='2549614'] Of course unless you play bass flute or whistle through your system, you will not be putting a sine wave through your system. [/quote]Nor then. All instruments save electronic have harmonic content, and no one I know of plays a synth patch that's a pure sine wave. The only instrument I can think of offhand that might play pure sine waves is the Tannerin (that's what's on [i]Good Vibrations[/i], not a theremin). I say might, as how pure the wave is depends on the quality of the oscillator and the attendent circuitry, and the speaker as well.

[quote name='Magic Matt' timestamp='1410451921' post='2549598'] 100Hz square wave would require the speaker to move over that 4mm distance instantly, then stay there motionless for half a cycle, then instantly jump back, stay motionless for half a cycle, etc... [/quote]That's part and parcel of the myth. It doesn't happen. Where a speaker is concerned there is no such thing as a square wave as seen on an oscilloscope. [quote] I'm not sure what you're saying by "breaking down a square wave into its basic components"... square waves are the basic component![/quote]That's also part of the myth. A square wave is a sine wave with all of its harmonics present with equal power density. Run a square wave through a brickwall low pass filter, its corner frequency set slightly above the fundamental, and you are left with the original sine wave. Further reading: http://forum.qscaudio.com/forum/viewtopic.php?f=29&t=2736

[quote name='Sonic_Groove' timestamp='1410437959' post='2549412'] If you could convert the SPL of an average acoustic guitar into watts how may approx would it be.[/quote]Assuming a level of 90dB at 1 meter that would be 0.001 acoustical watts per square meter. [quote]More specifically if you want to duet with an acoustic with bass what is the fewest watts you can get away with? [/quote]Impossible to say. First, watts are not a measurement of sound levels, they're a measurement of power consumption. To convert to what sound levels are measured in, decibels, you must consider a number of factors, not the least of which is that loudspeakers have very poor electrical to acoustical power conversion efficiency. From a practical standpoint the watts don't matter, the speaker size does. A typical ten inch driver loaded twenty watt combo will have no problems matching an acoustic guitar in output. For that matter an eight inch driver loaded combo will have adequate output, but those tend not to have very good low frequency response.

[quote name='Magic Matt' timestamp='1410422288' post='2549201'] Also, speakers can't produce proper square waves...It's going to have to accelerate, and decelerate, at each "end" of the waveform, and trying to stop instantly is probably going to introduce artifacts into the sound. [/quote]Logical, but that doesn't occur. On reason why is because voice coils are inductors, and like all inductors they are low pass filters. That being the case, a goodly portion of the harmonics that make a square wave square are filtered out. When you break down a square wave into its basic components it's not intrinsically different than any other complex wave form, and drivers have no more issues with them than they do with any other complex wave form.

[quote name='Magic Matt' timestamp='1410382508' post='2548928'] [color=#282828][font=helvetica, arial, sans-serif]Are we talking harmonics that are still lower than the fundamental frequency of the square wave[/font][/color] [/quote]Harmonics are multiples of the fundamental, so they're always higher in frequency, never lower.

[quote name='Magic Matt' timestamp='1410377714' post='2548836'] if the speaker can handle more power than the amp can put out, how is that any different to playing music through it that's been hard-limited, or a sound from a keyboard that's basically a square wave?[/quote]It isn't. [quote]Seems to me that this whole under-powering thing is just a load of nonsense... so what I am I missing? ...or aren't I? [/quote]Clipping can toast tweeter voice coils, because what makes a square wave square is harmonics not present in a clean signal. Those harmonics can increase the power seen by a tweeter tenfold over normal, and that's what toasts the voice coil: overpowering, not under-powering. BTW, this document is the source of the under-powering myth: http://www.jblpro.com/pub/technote/lowpower.pdf With the re-telling of the tale, probably by the first wag to do so, the key phrase 'high frequency components' was omitted, and the myth was born.

[quote name='Magic Matt' timestamp='1410365239' post='2548616'] I've bought a set of Mr. Fitzmaurice's rather excellent looking Simplexx 12 plans. I will probably follow those, but possibly vary a little to add batons in the corners, just purely for the sake of compensating for the lower quality ply. [/quote]Battens are a waste of wood and weight, as the corners of the cab are the strongest point of the cab. Suggest you join my forum to post any questions, and be forewarned that if you suggest any alterations there you will be told in no uncertain terms that there are three rules that you must not violate. They are: 1. Follow the plans. 2. Follow the plans. 3. Follow the plans. They'll also be able to tell you where to source your plywood.

[quote name='Magic Matt' timestamp='1410301280' post='2548088'] I couldn't see what drivers I'm supposed to buy for them...? [/quote]None, until you have the plans in hand and are able to weigh the options. There's very little difference in the cost of two 112 versus one 212, the only major one being the need for more jacks with two cabs.

I'd always go for two twelves over one fifteen, and for that matter two 1x12 over one 2x12. If you're thinking of a course change you should consider my Simplexx 12, as all of the R&D is done, as is the forty years of experience that went into that R&D. You just have to put it together.