Bill Fitzmaurice

[quote name='4 Strings' timestamp='1354616623' post='1887999'] Also explains why some people believe maple fingerboards make a guitar sound brighter. [/quote]Brighter than what, pine? Rosewood is brighter than maple, and ebony brighter than rosewood. The tonewood debate rages on amongst the wags in the same fashion that the driver break-in debate does. Luthiers don't debate tonewoods, because they know from experience what different density woods do. Loudspeaker designers don't debate break-in amongst themselves, for the same reason. But pundits will jabber on forever.

[quote name='Walker' timestamp='1354481938' post='1886548'] What would give more volume for the audience? Two 12" bass cabs together, or one either side of the stage? Or would there be no difference? [/quote]http://www.prosoundweb.com/article/in_search_of_the_power_alley/

[quote name='stingrayPete1977' timestamp='1354297030' post='1884633'] I think other people have had this issue with this cab [/quote]If it has higher sensitivity than another tweeter it will be more revealing of amp noise. You can compensate for that with the LPad, assuming it has one. Or is that something else that G-K left out?

Tweeters don't buzz. Amps do, and when they do tweeters will reveal it.

[quote name='4 Strings' timestamp='1354272503' post='1884263'] Running in of a car... [/quote]The running in of a car isn't a very good analogy. The wearing in of a pair of new unwashed jeans or leather shoes is, because they get softer with use, as do the suspensions on drivers. Like Alex I don't recommend breaking in drivers just because I think it might be beneficial, it's because I've measured the results of break in, literally hundreds of times. I very much doubt that the wags who say it doesn't do anything have any data to back up their assertions.

[quote name='solo4652' timestamp='1354195572' post='1883377'] Maybe cover both with some pink noise? [/quote]Pink noise doesn't properly flex the suspension. The BFB quoted link is correct.

Add another identical 210, vertically stacked above your existing cab. You can only get so much from one 210.

[quote name='dincz' timestamp='1353697247' post='1877667'] Sensible precautions, but the amp's voltage swing is equally important whether it's coming from a single amp/channel or a pair of bridged amps/channels. [/quote]OTOH if the voltage swing of one channel is more than adequate to drive the speaker to full output there's nothing to be gained from doubling that swing, and much to be lost, as in blown drivers. Admittedly it's a crap shoot when you don't know the voltage swing of the amp, or the displacement liimited voltage capacity of the speaker. If in doubt just assume that the cab cannot make use of more than half its power rating, and unless one channel of the amp cannot provide that don't bridge.

[quote name='fernandobicho' timestamp='1353640712' post='1876934'] [color=#222222][font=Georgia,]PAS BG1080C 8 drivers are 8 ohm and [/font][/color][color=#222222][font=Georgia,]BG1016C 16 are 16 ohm drivers. (Information in a 2004 thread in TB, by a PAS engeneer)[/font][/color] [/quote]Quite the trusting soul you are, but as Mr. Reagan said, "Trust, but verify". PAS might claim your drivers are 8 ohm, but without an impedance chart to back up that claim it's just that, a claim. The only evidence seen so far are your DCR measurements and similar results from others, which all point to them being 6 ohm drivers. As for why PAS might be less than truthful, if they sold them as 8 ohm drivers what else would you expect them to say?

[quote name='dincz' timestamp='1353607778' post='1876583'] And presumably: never buy an amp that uses a pair of bridged power modules for each output? My point being that if a speaker is being driven with, let's say, 40 volts RMS, it doesn't matter whether that 40 volts is being delivered by a single power amp channel or by 2 channels each capable of 20 volts. The speaker doesn't know or care - it's still 40 volts RMS. I don't understand this thing about bridging being a bad thing. It's simply a matter of sensibly matching the power ratings of amp and cab. [/quote]Does the amp manual state what the voltage swing is for both configurations? And does the cab manual state what the maximum displacement limited voltage swing is? If so the user can make a well informed choice as to how he should run the amp. Now try and find any amp manuals that state the former, and any cab manuals that state the latter. The product of those two figures will be [i]exactly [/i]zero.

[quote name='fernandobicho' timestamp='1353592554' post='1876372'] what do you think? [/quote]I'd call those 6 ohm drivers and a 6 ohm cab. I wouldn't be a bit suprised if SWR sold the same cab as 4 and 8 ohm, assuming that no one would bother to check. It wouldn't be the first time manufacturers have played fast and loose with the facts, nor the last.

[quote name='fernandobicho' timestamp='1353528494' post='1875727'] Thank you........ My situation it's to link mw Eden WT-600 in bridge (8 ohm minimum) to the cab or not If it's 8 Ohm, that's ok, if not I can't use the cab with my amp in bridge... [/quote]Never bridge. It's not about watts, it's about doubling voltage swing, which quadruples your chances of blowing a driver. The only exception is if you have a 16 ohm cab, which can actually make use of the higher voltage swing.

[quote name='fernandobicho' timestamp='1353526648' post='1875698'] I did some measurements: [b]THE GOLIATH 4X10 = 4,3 ohm (if multiply by 1,3 = 5,59)[/b] [b]EACH DRIVER FROM GOLIATH 4X10 = 4,4 (x 1,3 = 5,72)[/b] AN AGUILAR 12'' 8 OHM CAB = 6,4 (x 1,3 = 8,32) A GAUSS DRIVER 8 OHM = 5 (x 1,3 = 6,5) A 8 OHM DRIVER = 7,2 (x 1,3 = 9,36) A 4 OHM DRIVER = 3,2 (x 1,3 = 4,16) [b]So, the question is: THE GOLIATH 4X10 IT's 4 Ohm or 8 Ohm?[/b] Thank you in advance [/quote]The DCR tends to be around .7 x impedance, but that's not a hard and fast rule, the range is generally from .65 to .75. Keep in mind that impedance is a nominal figure, not an exact one.

[quote name='voxpop' timestamp='1353351661' post='1874136'] Would it be better to use this driver, I could do with a 16 ohm replacement instead of the current 8 ohm celestion. [url="http://www.lean-business.co.uk/eshop/eminence-delta-15-16ohm-15-400watt-speaker-p-774.html"]http://www.lean-busi...aker-p-774.html[/url] [/quote]It specs best with a sealed cab, and the 1.6mm xmax renders it almost useless for bass with much more than a 30 watt amp.

[quote name='LawrenceH' timestamp='1353344951' post='1873993'] That's not quite what I said. I was pointing out that your criticism of a design for having a built in hump was apparently at odds with your own design philosophy, you just have a different preference.[/quote]Intentional response humps to achieve a desired response have their place. Unintentional humps caused by poor design and/or inferior components do not, especially when situated at frequencies that are problematic.

[quote name='LawrenceH' timestamp='1353335721' post='1873744'] I find it odd that Bill is always so down on other people's non-flat designs, [/quote] I have [i]never [/i]said flat designs are superior. If I thought they were that's what I'd offer. [quote]when his own Jacks are very deliberately designed this way with a massive hump in the low mids[/quote] That gives a strong low mid presence to offset the accentuation an octave below typical of most rooms, quite the opposite of having a midbass hump in the same region where stages/rooms also contribute to response, adding to the problem of boom. [quote]comparatively little deep bass [/quote] Compared to what? They better most commercial cabs. Just look at the SPL charts for commercial cabs... oh, yeah, right,[i] there aren't any. [/i] [quote] it didn't work for me [/quote]And some prefer Lexus to Mercedes. To each their own.

[quote name='voxpop' timestamp='1353316061' post='1873435'] I have a cab the contains a Celestion BL15-400X driver. The cab has two 7cm holes cut into the front of the cab. To my ears it sounds better with the holes blocked with foam. It gets tighter and more dynamic. Why cut the holes into the front as it is clearly not tuned to any frequency as there is no tubes behind them. Seems to me it's a crazy design, or maybe there is no design or thought put into it. [/quote]That porting would tune a typical 1x15 sized cab to 70-80Hz, making it a one-note boom machine. I once ported a sealed cab in that fashion. I was 15 years old, hadn't the slightest notion of how speakers worked, never having even seen a ported cab, so the error of my ways could be forgiven. That forgiveness shouldn't be granted to a company that should know better.

[quote name='Protium' timestamp='1353272527' post='1873177'] Let's be honest, there's not a great deal of designing involved in making a rectangular box is there. [/quote]It's still beyond the skill set of marketing departments and executives. And even a seemingly simple box on the outside if well designed is anything but simple on the inside. Then there's the matter of crossovers, which are not the least bit easy to design properly. If it was as easy as it seems you wouldn't find so many cabs with inadequate or non-existent bracing and damping, nor any with horizontally arrayed drivers.

[quote name='RandomBass' timestamp='1353047389' post='1870872'] Yes I've always considered BFB to be a bargain, considering what you get. Expensive compared to mainstream? perhaps. But still a bargain. [/quote]Expensive? Not at all. BFB uses premium drivers, none of the 'mainstream' manufacturers do. For that matter neither do most boutique brands.

[quote name='Bassman62' timestamp='1352996423' post='1870320'] Many loudspeaker cab manufacurers use the least expensive speakers that they can get away with whilst charging phenominaly high prices for the finished product. Some few short years ago two of the most popular cabs from a leading UK manufacturer retailed at £499 each, these being a 4x10 and a 1x15, the 10" & 15" speakers left the actual speaker manufacturer for approx £9.50 (10") & £32 (15") each which equated £461 £467 for the empty cabinets which were basic tuned cabinets, nothing complex. [/quote]Look at what Orange charges for their 410, then see what retailers get for four Eminence Beta 10s. For the price one would expect the 410 to contain premium drivers, especially as Orange doesn't pay the retail price. [quote]All loudspeaker cabinet manufacturers do: Barefaced for example charge ~£525 for a compact. A £125 speaker, equating to £400 for a bit of plywood [/quote]OTOH that bit of plywood doesn't assemble itself. Rule of thumb for any manufacturer to stay in business they must make no less than the cost of all materials, labor, marketing and distribution plus 40%. Since BFB has lower marketing and distribution by selling direct they're a bargain.

[quote name='Beer of the Bass' timestamp='1352916677' post='1869382'] Although it'd be unwise to substitute in other drivers blindly, the Peavey cabinets are a fairly standard size and tuning, so chances are good that you can find another speaker that works in that box. If you measure the box and port dimensions, you can model the performance of different drivers using a piece of free software called WinISD, until you find something that performs similarly or better than the original driver. [/quote]Too much work. Just go to the Peavey site, get the T/S specs, find a similar driver. Similar, but not the same, as the 2.8mm xmax of the 1502 is marginal at best. The CA 154 is not compatable, and xmax is no better. As for replacing the basket, the 1505 is a much better choice, specs are compatable, but I don't know if the 1505 basket will work with the 1502 magnet. It's worth checking it out.

[quote name='Protium' timestamp='1352674208' post='1866064'] By the way, their amps/cabs are present on almost every major festival stage in this country. By that standard I reckon they know [i]exactly[/i] what they're doing [/quote]Perhaps. That doesn't mean they don't cheap out on drivers, just that they're no worse than most other companies in that respect. And you're assuming that they design their own cabs. Most companies do not, farming that job out to independent speaker designers, like me. That gives me the unique opportunity to know exactly what manufacturers do to maintain the highest possible profit margins, and that seldom includes using the best drivers available.

[quote name='LITTLEWING' timestamp='1352643566' post='1865467'] I can't help thinking the cab could be upgraded with a couple of ports in the front of the sealed cab. [/quote]In order to vent the cab you must have the driver T/S specs and use speaker modeling software to see if it will work, and if so determine the required vent configuration, if the drivers have specs compatible with a vented cab to begin with. [quote]Ashdown must know what they're doing![/quote]Don't be so sure. As often as not drivers are chosen based on their price, not how well they function.

[quote name='andyjingram' timestamp='1352215142' post='1860224'] A larger body of air behind the speakers will of course affect the depth of the lows [/quote]What matters is the volume of air per driver. When considering two 1x versus one 2x that's what you look at.

With respect to the OEM Sica, the Qts of 1.16 means it's only suitable for a sealed enclosure, and will have a boomy response with weak lows, while the 2mm xmax limits actual low frequency power handling to perhaps 25 watts. In short, it's a really crap driver. The neo driver specs are much better, but the 3mm xmax is still marginal. IMO 4mm is the minimum acceptable.