Bill Fitzmaurice

[quote name='essexbasscat' timestamp='1334852509' post='1622411'] I guess to clarify my question, how does the one speaker mechanically produce [i]n [/i]different sounds ? [/quote]It doesn't. The waveforms of all of the various sources combine into one waveform.

[quote name='gapiro' timestamp='1334789568' post='1621493'] I think a compact maybe the way forward. [/quote]If you want to do so using only it you'd need a new amp too, as you don't have enough power to drive the Compact to full output. The point of adding the second cab is to get the added sensitivity and power that results from two cabs. And if you add a second cab you want them displacement matched, otherwise should you ever go to a big amp you won't be able to go any louder than what the cab with the smaller displacement will allow.

[quote name='gapiro' timestamp='1334664595' post='1619315'] Currently I have a Hartke HA2500 running into a Barefaced Midget T. I love this setup, I love the sound and the cleanliness of it. However I am simply not getting enough volume at gigs from it. [/quote]Add another Midget T. You'll get a 6dB bump in output, the equaivalent of quadupling your amp size, with no changes in tone. And with the second cab atop the first it will be closer to your eaars, making it seem louder still.

It's not new technology, Carver had it 25 years ago. There are two power rails, one for low voltage/current draw one for high voltage/current draw. The result is higher efficiency than typical Class AB, not so high as Class D. Class A is so inefficient you can get double duty using it to heat your house.

You model the Karson as a series tuned 6th order bandpass, WinISD doesn't have that capability. Those odd looking tubes are another bit of Karlson kit that defies explanation.

Yes, you can use car audio gear to make a bass rig, [i]so long as you're playing inside a car[/i]. Otherwise, forget about it.

[quote name='StraightSix' timestamp='1333808532' post='1606793'] Thanks for the clarification Bill - that's very poor in terms of performance. [/quote]Awaiting the caterwallering replies from the "I don't care what the numbers say I love mine" set.

[quote name='JTUK' timestamp='1333803366' post='1606712'] get an Orange 410 [/quote]SP410 displacement 300cc. Barefaced Compact displacement 566cc. The advantage of 566cc versus 300cc is just as significant as it would be If these were motorcycle engines. [quote]The regular Orange 4X10 will give a Volume displacement of 600cc[/quote]The Beta 10s used in the OBC 410 have only 102cc displacement each, for a total of only 408cc.

[quote name='jackhammer' timestamp='1333748229' post='1606161'] It's a bit..... Like something's missing.. [/quote]You're not missing a thing. Get past the advertising nonsense that wants to make you think otherwise. The problem with mixing cabs is that the result is totally unpredictable. The best course is to buy the cab that you like the sound of best. If one isn't loud enough use two.

[quote name='jackhammer' timestamp='1333745432' post='1606118'] the 4x10 is 51Hz to 18Hz and the 2x10 is 53Hz to 18Hz, whats the difference :s [/quote]2Hz.

[quote name='CJPJ' timestamp='1333734029' post='1605922'] I haven't always felt the power through the SP210 when turning up the dial and have recently experienced the cab farting at higher volumes with gain. I thought this was a bit strange since the amp is on 500w against the cab's 600w. [/quote]The cab's 600w rating is moot, it only says how much power it will take before the coils melt. How much power it can use before farting out is a matter of the driver displacement. The displacement of the drivers used is 150cc. With a normal 210 that would come to 300cc total, but the SP210 isobaric configuration only exposes one cone to the air, so the effective displacement is that of one driver, 150cc. That's the price paid for the small cab size. IMO that price is far too dear. To see how it measures up to what's IMO a far better option have a look at the displacement figures shown here: http://barefacedbass.com/technical-information/Volume-displacement.htm Doubling driver displacement offers the same increase in volume as quadrupling your power output.

[quote name='Moos3h' timestamp='1333621364' post='1604305'] Thanks - I'm thinking I'll do what Stevie says and find a piezo tweeter, wire it up outside the cab and see if I like it. [/quote]It's not that simple. First off you need at least two piezos series wired to withstand the voltage swing, a single unit won't do it. And while piezos are advertised as not needing a crossover that's not actually the case, for professional use they most definitely require filtering, and there are no 'off the shelf' filters for piezos, you must construct one yourself. True many manufacturers do just toss in a single unfiltered piezo, but only because that's the cheapest way, not because it's the right way. The right way to get better high frequency response without tearing into your cabs is the fEarful headcase. http://greenboy.us/fEARful/

As the old saying goes, if you have to ask... In any event midrange drivers work far better than tweeters, which don't start working until an octave higher than you want, and continue to operate an octave higher than you need. Either way the installation is simple if you know what you're doing, but might as well be rocket science if you don't.

RMS is what engineers use when desiging gear. All else is what marketeers use when advertising it.

[quote name='Salt on your Bass?' timestamp='1332920603' post='1594753'] As I've never played outdoors before, I wasnt sure what affect this has on a bass rig. . [/quote]You lose space loading, which costs you 6dB of net axial low frequency output. To compensate for that you need twice the speaker count as indoors to reach the same levels, both on stage and in the audience, unless you happen to have 6dB of low frequency headroom that you can afford to lose.

[quote name='Lozz196' timestamp='1332875792' post='1594383'] It does make a huge difference. I had an Eden 410 that was 103. Amp volume on 3. I then had a Hartke 410 at 99. Amp had to be on 4 or 5 to get the same volume. I now have a Schroeder 21012 at 104. Amp can go to 3, but it be darn loud. 2 and a bit is better. [/quote]Speaker voicing also makes a huge difference. Both Eden and Schroeder have high tuning, which accenuates sensitivity in the midbass. That boosts midbass sensitivity, but just as important, midbass is more audible than bass. The Hartke probably had higher sensitivity in the lows, so subjectively it wouldn't seem as loud, even though it might have been actually considerbly louder in the lows. In any event never trust manufacturer SPL specs. They're only as good as the measured SPL chart that accompanies them, and [i]there aren't any[/i].

[quote name='LawrenceH' timestamp='1332509605' post='1589358'] On the flip side the Omni is a structurally unusual cab, it's much more asymmetric and the design is already inherently heavily braced thanks to the horn and internal baffle compared to a typical nasty box, not necessarily the most relevant comparison. In a more typical scenario a cross brace right into the centre of a panel would presumably damp the lowest mode but set up a symmetric pattern of vibrations above this, which can reinforce thanks to the symmetry. In the real world though any bracing at all is a lot better than none and I think a law of diminishing returns applies quite quickly - plus, shift the resonance higher and it's easier to absorb anyway. I was actually surprised how little subjective difference damping appeared to make in a braced, tweeterless cab I built recently - much more important for full-range and hi-fi use I think where the HF (although unaffected directly) gives 'context' to what you're hearing lower down. But perhaps that was also partly due to all the bracing which made the inside highly asymmetric anyway! [/quote]That's all logical if one accepts that the purpose of bracing is to shift the resonant frequency of the panel upward. It isn't. The purpose of bracing is to reduce the flexing of panels in response to the air pressure inside the cab alternately pushing and pulling against the panels. If that is not done energy that otherwise would be useful acoustical output is lost. That's best accomplished by minimizing the size of the unbraced areas between braces. A side effect of so doing is that the resonant frequency of the panel is raised, but that's a side effect which in and of itself does not impact the response of the speaker.

The center of the panel is the most important bracing point, as it's where the panel is subject to the greatest flexion. The cabinet should be fully lined to absorb all internal reflections. BTW, greenboys text is very well done, and I might add that it reads better than my Omni cab plans that was the original source. That would be the same cab that I built in both spline and cross braced versions to confirm by measurement which bracing scheme worked better, and by how great a margin.

[quote]the problem is that there isn't a single mathematical model that will predict the total effects of either damping or bracing. [/quote] There are. A civil engineer would be quite comfortable with the bracing aspect, while advanced speaker modeling software can accurately predict the effects of various thicknesses of damping materials based on their index of resistivity.

[quote name='LawrenceH' timestamp='1332325212' post='1586547'] Hmm...so your rods method raises the resonance further due to stiffening in that design? I must say that directly contradicts my experience. If an engineer wants to stiffen an internal structure like this they typically use i-beams, not point contacts which still allow flexure around the point, so if your method works better there must be more to it than overall wall stiffness [/quote]Raising resonance in and of itself does nothing; what's the resonance of a six inch thick concrete cab? If a panel is not stiff enough to withstand the pressure generated within the cabinet it will vibrate. If it's too stiff it won't. Your I-beam comparison is correct, but the most effective i-beam configuration is with the i connecting the 'beams' of opposing panels, so that the opposing vector forces against those panels cancel each other out. There are no opposing vector forces with a spline brace. [quote]It seems there is more than one way to effectively brace a cab.[/quote]I once used those methods, but stopped after I actually built two versions of the same cab, one using spline, one using cross bracing, measured the results, and found cross bracing to be far superior. ...

[quote name='LawrenceH' timestamp='1332282640' post='1586220'] Depending on the types of vibrations/resonance seen I'm not sure the rods method will be as effective as stiffening the cabinet with conventional parallel braces running along the open faces of the panels. [/quote]They're more effective. [quote] glued-in parallel braces would seem to have a greater impact on raising primary panel resonance frequencies as they're providing stiffening along more of the panel's surface. [/quote]It's not the raising of the resonance that makes the cab better, it's the stiffening of the structure. The raising of the panel resonant frequency is a side effect of that stiffening. Cross bracing is no less than twice as effective as spline bracing in so doing.

[quote name='xgsjx' timestamp='1332269890' post='1585905'] & the 4Ω cab would probably only put out 3 db more than the 8Ω equivalent. [/quote]It may have 3dB higher sensitivity, but not 3dB higher output. Output is limited by displacement, displacement is not altered by impedance.

[quote name='Dave Tipping' timestamp='1332274032' post='1586003'] ... In my typical manly way of having to take everything I own apart , I discovered tonight that my Laney Nx115 Cab has NO dampening at all .. and also no internal bracing . It really doesn't sound bad with my Orange head .. but I have been dialling a fair bit of bass out the eq to get it sounding how I want. Questions : 1. What would be the best method of bracing it? [/quote]This, using 25mm dowels glued in place. Line it with either open cell urethane foam or polyester batting, as used in uphostery. One average 25-50mm thick, secure it with spray adhesive. [quote]tried putting some spare Spectraflex Deflex panels in my Trace 2x10. All it did was make it even heavier.[/quote]cabinet damping weighs next to nothing, so whatever you used was the wrong stuff. [quote]The idea of bracing was to be able to make efficient cabs (acoustically and mechanicale) out of lighter materials - if your Laney hasn't got bracing then it probably doesn't need it and the same is probably true for the dampening material.[/quote]All cabs should be braced and damped. Those that aren't are defective. The only reason for not doing so is to save on build costs, pure and simple.

[quote name='sixdegrees' timestamp='1332267960' post='1585872'] Surely if you went for a 4 ohm cab in the first place, and got full power from the head, you would be less likely to want to add an extra cab to get more volume/presence? And the 4 ohm option would be kinder to the head in the long run. [/quote]No, and don't call me Shirley. Getting full power from the head is moot, driver displacement is what limits output. Nor will a 4 ohm load be kinder, the lower the impedance load the higher the current draw, the higher the current draw the more heat produced, more heat shortens component life.

[quote name='Pete Turton' timestamp='1332178077' post='1584390'] [size=5]I have a great little Marshall MB4210 combo that I love and am going to add a 15" cab for a little more bottom-end.[/size] [size=5]As it is, its pushing out 300 watts @ 4ohms and with extention cab will go to 450 watts @ 2ohms. Marshall have a MBC 15" cab that is rated at around 300 watts, but I have the chance of buying a Peavey 15" cab, 4ohms, but pushing out 150 watts. Would this be suitable as it takes the total wattage to the amps needs?[/size] [/quote]Watts are immaterial. You want a fifteen with the same impedance as the two tens combined and at least as much displacement. The trick will lie in finding out the displacement of the tens you have and the fifteens you're considering. As for what displacement is all about, and why it matters while watts don't, have a look here: http://barefacedbass.com/technical-information.htm