Bill Fitzmaurice

[quote name='Mr. Foxen' timestamp='1324413573' post='1474041'] If DC did break voice coils, most of my cabs would break because I use a 9v battery to check I wired all the speakers in the same polarity. [/quote]+1. A case of another myth that has its roots in reality. If you blow your amp output devices that can result in a direct connection from the supply rails to the speakers, and that can toast them. Not because it's DC, but because the voltage is more than the drivers can handle. In short, overpowering. [quote]If DC alternates then it isn't DC anymore! [/quote]+1. Sources that say a square wave is DC should be universally ignored.

[quote name='4 Strings' timestamp='1324394867' post='1473798'] That's not it at all, Alex. The difference isn't before sounding dirty, the valve amp is incomparably louder. I know what you mean about clean, I only mentioned it as I was not comparing dirty/clipped/overdriven sounds. I'd love to know the reason why. [/quote]Compression, which valve amps do naturally without an outboard device. One can even tell the difference between valve amps that use valve power rectifiers versus SS rectifiers, as there's compression on the DC supply rails with valve. Keep in mind that honestly rated amps, which is most of them, are measured with a specific voltage into a specific load at a specific distortion percentage. When compression occurs THD goes up, so a tube amp honestly rated for 100w at 0.1% THD will have much more power at 10% THD, and the increased power density that results from compression makes the amp subjectively sound much louder still. With sufficient processing an SS amp can do exactly the same. Tubes just don't need the added processing. In the case of the TC they rate their amps with processing factored in, therefore at a very high THD. It's equivalent to measuring a car's gas mileage while traveling downhill with a tailwind.

[quote name='guildbass' timestamp='1324378032' post='1473498'] Now that's what I've SEEN happen out in the world. That's what I've observed happening on a scope,[/quote]What you see on a scope bears no resemblance to an actual musical waveform. In the real world what clipping does is to increase the power density in the harmonics. This greatly increases the voltage swing seen by tweeters, which can toast them. It does not significantly increase the voltage swing seen by a woofer.

[quote name='guildbass' timestamp='1324338355' post='1473296'] What kills cabs...or rather drivers, is Dc voltage, and the more an amp clips, the flatter the signal peaks get. Clip it enough and those flat plateaus add up to a solid elevated DC voltage...And that will brew up the driver coils. A 10 Watt HiFi amp can happily kill a 500 watt speaker if it's clipped hard into it for long enough. [/quote]No. Total myth, I'm afraid, one which is summarily dismissed every time it's unfortunately regurgitated.

Pushing air isn't about the number of drivers, it's about their displacement. Keep the car, get a high displacement Barefaced.

[quote name='chris_b' timestamp='1324254709' post='1472369'] [size=4][color=#222222][font=Arial]"Watts" are [i]not[/i] a scientific measurement. Only RMS watts is, and I don't recall TC claiming RMS. [/font][/color][/size] [size=4][color=#222222][font=Arial]Why do people keep banging on about full pints, half pints, being short changed? TC is selling an amp that in volume equate to a 450 watt amp. That’s the number that is important here, not the number before it was processed and boosted, that's the number you use when comparing its loudness to other amps, that's the number you use when you are buying cabs for it. That’s it!!! [/font][/color][/size] [size=4][color=#222222][font=Arial]You can like the sound and you can hate the sound, that's ok, but all this "I've been sold a 236 watt amp and I've been cheated" bleating is getting tiresome. [/font][/color][/size] [/quote]Bernie Madoff could have used you on his defense team. The only difference is scale, not intent.

[quote name='xgsjx' timestamp='1321047235' post='1434978'] Regardless of wattage, the RH450 is still a very good amp. [/quote]No argument there. I've not found anyone who says that it isn't. But when one goes into a pub and pays for a pint one expects to get a pint, not ten ounces, no matter how good it tastes.

[quote name='klaw123' timestamp='1324165095' post='1471506'] he cab would be awsome at 800watts but is is the best thing to do? [/quote]Driver power ratings are their least significant aspect. What matters are T/S specs ( [url="http://www.eminence.com/support/understanding-loudspeaker-data/"]http://www.eminence....udspeaker-data/[/url]) and frequency response. Driver swapping/replacement is dicey if you don't understand these factors and how to apply them. If you want to preserve your current performance re-coning your blown drivers is the best route. Dropping in new drivers based only on their size and power ratings is a risky proposition.

[quote name='Skezza' timestamp='1324137485' post='1471208'] Thanks I did not realise that the cabs used a specific driver I bought it secondhand the driver thats in is an Emminece beta 10a which i am pretty sure is 250 watts into 8ohms I was going to use it with my 4 ohm 1 x15 is that ok [/quote]Never mix cabs. Most especially never mix horn loaded cabs with direct radiators.

[quote name='Skezza' timestamp='1324136143' post='1471193'] Hi Im looking to replace the 8 ohm speaker in a Bill Fitmaurice Jack 10 enclosure with a 4 ohm speaker I cannot seem to find a 4 ohm 10 inch bass speaker which must be at least 200 watts (preferably 400 watts) any suggestions of something suitable skez [/quote]Like all cabs the J10 requires specific driver T/S specs. And watts don't matter, xmax does. And, unless you have a valve amp that requires a 4 ohm cab, there is no benefit to changing the driver,

[quote name='Marvin' timestamp='1324056989' post='1470457'] I sort of understand what 'beaming' is. This is a question out of sheer curiosity, how does speaker configuration affect beaming? Or what affect does speaker configuration have on beaming? [/quote]The angle of dispersion is inversely proportional to the size of the source. That's the #1 reason why midranges are smaller than woofers, and tweeters smaller still. Guitars have most of their frequency content above 1kHz, where the dispersion of a twelve is rapidly collapsing. Worse, when two twelves are placed side by side their dispersion on the horizontal plane falls to that of a twenty-four inch driver.The simple solution is to use eights and tens, not twelves, and stack them vertically, for maximum dispersion on the horizontal plane. But, while most guitarists are acutely aware that their cabs beam, as with the weather they complain about it but no one really does anything about it.

[quote name='4 Strings' timestamp='1324024201' post='1469792'] I have the opposite problem, as bass has more omni-directional frequencies (Bill?)[/quote]Bass cabs are omni-directional to about 250Hz, and don't beam much below 1kHz, so they're generally not hard to hear on stage unless cancellation modes mask their output.[quote] I never get much of the guitarist from the other side of the drummer nor the keys next to me but with his speaker the opposite side of him.[/quote]That's because most of their bandwidth is in the directional frequencies, and if their cabs have drivers placed side by side they're beaming through most of their range. The only solution is to have them in the monitors.

[quote name='ficelles' timestamp='1323991498' post='1469705'] . is an 8 x 10 a point source or a line source? [/quote]It's both, as are all speakers, depending on frequency and how far away the listening position is. Practically speaking all electric bass cabs should be considered point sources, save maybe a pair of 810s stacked vertically.

Tilting the cab back works too.

These symptoms can usually be traced to the venue, being caused by room boundary interactions, and changing the speakers would have no effect. All speakers lose volume with respect to distance via the same equation.

[quote name='Ghost_Bass' timestamp='1323798742' post='1467258'] Humm... i doubt the driver was changed... the previous owner was a BC member so he must definetly be an honest person! I'd rather believe that the driver used has somehow the same roots as the 3012 or that it could have been based on it's development... [/quote]There's also the possibility that whoever wrote the G-B ad copy that states a 7 oz magnet and 2 1/2" coil was wrong. Or that the driver was downgraded to a 2512 frame when the neo price hikes hit.

[quote name='Ghost_Bass' timestamp='1323780524' post='1466883'] Bill, if Jeff is using a 2512 based driver they must be very diferent from the stock ones because the frame and magnet are the same as the 3012HO [/quote]The 2512 and 3012 frames are almost identical visually. You'd be very hard pressed to tell the difference in pictures. The heatsink and rear cup of the 3012 are larger in diameter, to accommodate the eleven oz. magnet and 3 inch coil. Since the G-B driver has a seven oz. magnet and 2 1/2 inch coil it's a 2512 variant. BTW, the 2012 has a 2 inch coil, the 40xx series 4 inch coils, so you should see a pattern in their model numbers. There are OEM 2512s with longer xmax than the standard version, but as is always the case when you change one thing you change everything, and those versions give up midrange extension and sensitivity. A 300w coil is a possibility too, but that means a larger gauge wire, which means higher Mms, which means higher Qes and lower sensitivity. I have one such sample, and sensitivity is 94dB, compared to 96dB for the stock version.

[quote name='jimcroisdale' timestamp='1323713533' post='1466156'] I thought the 5mm+ Xmax was a significant improvement over most OEM drivers? [/quote]The Ampeg ten has 4.7mm. It's true though that many OEMs aren't as good as the Ampeg. [quote]The 2512 has a cast frame, which from what I understand, in general leads to greater stiffness/less resonance compared to typical pressed steel (as seen in the basslite). The frame is also important for wicking heat away from the driver, and cast alu should be better at that so in theory you'd expect the deltalite to show reduced power compression in comparison to the basslite[/quote] The 2512 has a larger coil, which gives it higher power handling, which requires more heatsinking. The Basslite doesn't use a cast frame because with its rated power it doesn't need it. If you believe the Ampeg spin doctors a stamped frame sounds better, but that's one wagon I won't jump on.

[quote name='jimcroisdale' timestamp='1323710054' post='1466108'] As a slight aside, knowing what I now know about xmax and fartout, do you think that manufacturers use the Deltalite 2512 instead of the Basslite 2012 just so that they can quote the higher wattage? [/quote]Probably. Even then G-B is stretching things claiming 300 watts. Not so long ago they were also claiming -3dB to 45 Hz. They were called out on it and now they're claiming -10dB. I'd be inclined to run a 2512 in a 112, I do in mine, just to have some extra thermal capability, but in a 212 I'd save the $ and use 2012s. As far as performance goes the 2012 is the equivalent of the average stamped frame OEM ceramic driver.

[quote name='Ghost_Bass' timestamp='1323692917' post='1465802'] I'm almost certain that Genz Benz uses the 3012 [/quote]G-B uses the 2512 motor: [i]2 1/2" ...voice coil...7 oz Neodymium magnet[/i]

[quote name='Mr. Foxen' timestamp='1323619687' post='1465084'] Not comparable to the Fearful again. [/quote]+1. Not even close. Very few manufacturers are using 3012 based drivers. AFAIK only Barefaced, AudioKinesis and Baer do.

Prices for neo drivers have gone up just as much for manufacturers. It's the reason why Bergantino stopped making their neo cabs.

[quote name='Merton' timestamp='1323017793' post='1458323'] Good point, I guess they (claim they) did the first bass-specific 4x10 but the format no doubt predates them. [/quote]Fender was doing the 4x10 Bassman combo in the mid 50s. Using guitar drivers, of course, as bass drivers did not yet exist. For that matter neither did guitar drivers, they were all classified as musical instrument.

[quote name='xgsjx' timestamp='1323005516' post='1458129'] ...could be due to the fact that it's been marketed like that for so long that the marketing dept (whom aren't engineers) don't want to take a chance & just stick with what they believe the average bassist will buy. [/quote]That. When I contract with a manufacturer to design a cab for them (because they have no engineering department; most companies do not) the specifications are laid out by the marketeers and bean counters. The number one consideration is how it will look, because looks is what sells cabs. The number two consideration is build cost, as these companies are in business with the intent of making a profit. My job is to then do the best I can within those constraints. Sometimes the restrictions I have to work within make it impossible to create what I'd put my own name on. But contract designs don't carry my name, so I just hold my nose and cash their check.

[quote name='allighatt0r' timestamp='1322946821' post='1457688'] using 410s for bass was born out of borrowed guitar cabs, and 115s being born out of borrowed PA subs back in the day. [/quote]Quite right. 30 years ago and more, when 410s were loaded with guitar drivers and 115s actually had the capability to go lower with more displacement than a 410 the 410/115 made sense. But continuing to do so 'because that's the way we've always done it' is as logical as mating a team of Percherons with a Rover for extra pulling power.