Bill Fitzmaurice

[quote name='JohnFitzgerald' timestamp='1355317933' post='1896808'] Bill Might this explain the logic behind the slot opening in the old Trace BKLX combos ? [/quote]Slot loading makes the cab a bandpass, so that kills highs and mids anyway. But to the extent that they still are there a vertical slot will give wider dispersion than a horizontal slot. Diffraction is the mechanics in this particular instance, how it works is shown here: http://www.acoustics.salford.ac.uk/feschools/waves/flash/diffractionslider.swf While the diffraction model doesn't precisely explain the benefits of vertical placement, or for that matter the wider dispersion of a smaller driver, it's close enough.

[quote name='alexclaber' timestamp='1355317189' post='1896794'] The attached plots are the same driver, the first measured in the summer, the second measured in the winter - ignore the LF stuff because it wasn't set up for that, it's a midrange/treble response measurement. The lower temperature changes the cone and the suspension stiffness - and look what that does to the frequency response curve! [/quote]If I'm doing measurements in the spring or fall I take the driver/cab inside the house the night before, rather than leave them in my unheated shop. There's a significant difference between a measurement of gear that's at room temperature versus even 60F, let alone colder than that. I learned that the hard way measuring a new HL10c driver that I'd left out in the shop, where the ambient dropped to 35F overnight. Spec'd at 44Hz, it measured cold at 70Hz. [quote]If it was that critical, I would imagine that the driver manufacturer themselves, or at least the cab manufacturer would do the running in for you...[/quote]Break in takes time, time is money.

While I deal with theory all the time I don't blndly accept it. I verify it by taking my own measurements, of both drivers and finished cabs before and after break-in. Those measurements verify that break in does exist and is audible. So, to go back to the original question posed by the OP, [i] Is there such a thing as a "playing in" period for a new speaker?[/i], the answer is yes. Over, and out.

Horizontal dispersion is inversely proportional to the width of the source, so having the two tens vertical will double the dispersion angle compared to having them horizontal.

[quote name='Jack' timestamp='1355265569' post='1896242'] PS - I can't speak for BFM, maybe he wasn't saying that. [/quote]In fact, I was. Everyone's entitled to an opinion, but if you want to offer an expert opinion you first must become an expert. Like Vance Dickason. Or the guy who's name is directly below his on the masthead of AudioExpress magazine, and Speaker Builder magazine before that: Mine. OTOH I studiously avoid offering technical advice on car forums, even though I drive one every day. [quote]I know little about the scientific measurements behind the the claims , but I am pretty sure the newness of lots of stuff subtly wears off from lots of new kit , sit in a chair , after a while it fits you better , wear some new shoes after a while they fit better , I am sure someone will debunk that with a very good scientific argument , but my arse sits better in my worn chair and my feet feel sooooo much better in my old shoes.[/quote]Very unscientific, but also absolutely spot on.

[quote name='gjones' timestamp='1355212660' post='1895331'] Is this one still going? It must be a record! [/quote]If you ignore the replies from all those not actually in the loudspeaker business it's a lot shorter.

[quote name='funkle' timestamp='1355008105' post='1893009'] Roger Sadowsky seems to believe that fingerboard wood may be more important to tone than even body wood - [url="http://btpub.boyd-printing.com/iphone/article.php?id=1236876&id_issue=135014&src=menu&ref=http%3A%2F%2Fbtpub.boyd-printing.com%2Fiphone%2F%3Fi%3D135014%26p%3D%26search_str%3D%26noframe%3D%26r%3Dhttp%253A%252F%252Fwww.bassgearmag.com%252Fbgm%252FMagazine."]http://btpub.boyd-pr...m%252FMagazine.[/url] He also seems to think maple is brighter than rosewood. [url="http://www.sadowsky.com/pop/roger_talks.html"]http://www.sadowsky....oger_talks.html[/url] [/quote]My opinion is based on a having built basses and guitars with various body, neck and fingerboard materials too, and I quit the search when I got what was perfect for me.

[quote name='alexclaber' timestamp='1354886040' post='1891607'] The old EA CXL112 is an 8 ohm nominal cab with a 4 ohm nominal woofer. I heard it explained as that once the voice coil is up to playing temperature it's then measuring more like an 8 ohm woofer, though that doesn't help if your amp shuts down before that point... [/quote]Quite the hocus-pocus that, but not surprising from a company that claims to make transmission lines when they are not.

[quote name='brensabre79' timestamp='1354730983' post='1889760'] Most maple fingerboards are covered in laquer, which is a very hard surface wheras rosewood generally is not. A well respected Brighton luthier told me that it is usually maple fingerboards that get that 'clanky' sound that many who prefer them are after. But he said that if I had a rosewood board and laquered it I would also get pretty much the same experience. Which is probably why Rickenbackers sound that way, despite have a rosewood board, because they laquer them... Breaking in speakers is definitely a given though [/quote]Both brightness and sustain are enhanced by denser woods, reduced by less dense woods. The finish will have some effect, but not that much, unless it's a hollowbody. The fingerboard material has the least effect, followed by the neck material, with the body material having the most effect. While typical hardwood bodies like maple and ash give a lot better sustain and brightness than softer woods like birch and basswood they pale in comparison to tropical hardwoods like rosewood and ebony. But tropical hardwoods weigh a ton, so they're generally reserved for neck and fingerboards. My bass is all rosewood, but weight isn't an issue, as I used the same semi-hollow body construction as Rickenbacker employs. It weighs less than a poplar body Fender, but is brighter and sustains better than any commercial bass I've ever heard. I can hit a harmonic and let it ring literally indefinitely, until I damp the string.

[quote name='solo4652' timestamp='1354662242' post='1888982'] I tried it at band rehearsal tonight and it wasn't loud enough. [/quote]I can't imagine it would be, other than for solo practice. You can only get so much out of a small 1x10 cab. IME 110 combos are good guitar rigs, but not good bass rigs.

[quote name='4 Strings' timestamp='1354629502' post='1888358'] Rosewood. I agree, if there is any difference (which I doubt) then the slightly harder the wood on which the metal fret is mounted the brighter the expected sound. [/quote]There's a difference, but slight, it is only a thin piece of wood. The body and neck material effects far overshadow that of the fingerboard.

[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.