Bill Fitzmaurice

[quote name='andyjingram' timestamp='1352199258' post='1859880'] So would anyone notice the difference between 300 and 500 watts through identical cabs? With the way the human ear works, the answer remains, probably not. [/quote]If the cabs are actually capable of handling 500 watts without exceeding the driver displacement limit the 2dB difference would be audible, though just. But what remains is the question as to whether the drivers can handle 250w each before exceeding xmax, and most twelves cannot. The displacement limited power handling of a speaker is one of the most important specs, if not the most important for bass cabs, yet one universally ignored by manufacuturers.

With 73Hz Fs the Celestion isn't well suited to electric bass. I wouldn't use a driver with higher than 55Hz Fs.

[quote name='xgsjx' timestamp='1352145207' post='1859397'] But would anyone really notice the difference in volume between an 8 ohm & a 4 ohm 2x12 (both of the same brand, etc)? [/quote]Probably not.

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[quote name='jonunders' timestamp='1352111589' post='1858717'] Hi Are there any advantages or disadvantages in having two 1x12 over one 2x12 or vice versa. Jonathan [/quote]You can't leave half of a 212 at home when you don't need it.

[quote name='gilmour' timestamp='1351611049' post='1853238'] specifically above I'm worried about Line level/instrument level thing. [/quote]That's key. Pedals are made to operate at 100mV or so, effects loops are at line level that runs around 1v, so most pedals won't work in a loop. If yours do you're in luck.

[quote name='alexclaber' timestamp='1351066008' post='1846747'] But something is definitely happening, you can hear it when you add or remove inter cab/floor damping! [/quote]It is happening, just not in the frequencies where one expects it. When you measure in room with and without isolation the difference is seen in the lower mids, not the lows. That's on a bare wood floor. On a carpeted floor there's no difference. What's really telling is when you measure in the room below where the speaker is placed. Frequencies capable of exciting floor vibration to the extent that it's audible also pass through the floor. When you measure in the room below there's no difference between isolated and not.

[quote name='pete.young' timestamp='1351010857' post='1846211'] FWIW, even if the maths say that a Gramma pad can't work, it does have a noticeable effect on boomy stages. I have no explanation. [/quote]Read my posts again. I never said that a Gramma can't have an effect, just that it doesn't work via the methodology that they claim. As for Alex's device, I'd lean towards foam as a material as well, because it's so easy to cart, and any isolating of the cab from stage vibrations that it might offer can't hurt.

[quote name='LawrenceH' timestamp='1351006496' post='1846113'] Efficient transfer of energy by a lightweight but rigid cab (without damping) will give greater vibration transfer to a resonant body like the floor. Mass greatly increases the force required to produce a noticeable reaction. This is secondary school physics in action! [/quote]One does not need a post graduate degree to know that if over 95% of the energy being output by the speaker is acoustical, not mechanical, then isolating that 5% is not going to stop the floor from vibrating, nor will the reduction accomplished have an audible result. But at the least one needs to have taken undergraduate courses in acousttcal engineering to know that over 95% of the output of a speaker is acoustical, not mechanical. The schlockmeisters who claim that their products will prevent a speaker from causing the floor to vibrate are well aware that the vast majority of consumers have no formal education in acoustical engineering, and that being the case many of them will accept their advertised claims at face value. At least enough of them to keep them in business. Alex at present doesn't fall into this category, having only stated so far that isolation does have an effect, but not the effect that Auralex for one erroneously claims. [quote]I (and I believe Sir Isaac Newton) disagree Irrespective of the stiffness of the cabinet or whether the sides are vibrating, Newton's laws/conservation of momentum means that if you are moving the speaker cone forward then the rest of the cabinet will to move backwards by an amount inversely proportional to their relative weight of the two parts (i.e. the cone/coil and the rest of the cabinet), so that the net momentum change is zero. This would occur even if it were in a vacuum.[/quote]Sir Isaac and myself are in complete agreement. When the cone moves back and forth it alternately pressurizes and de-pressurizes the surrounding air. Said pressurization and de-pressurization causes your eardrums to move back and forth in reaction; that's how we hear. Said pressurization and de-pressurization also causes the floor to move, how much being a property of the stiffness and mass of the floor. If the floor was vibrating in reaction to the walls of the speaker vibrating said cabinet walls would have to be moving as far as the cone does.

[quote name='alexclaber' timestamp='1350996617' post='1845973'] I was sceptical of cabs physically transferring vibrations to the floor directly but as bits of foam make a difference then something is clearly happening! Maybe what actually happens is that the cab is acoustically exciting the floor but by raising the cab on some suitable foam you damp the vibrations, as you now have a damped mass on the vibrating membrane - like the difference between fretting a string and muting a string? [/quote]It's closer to the difference between playing your bass with its body touching or not touching the cab. If the floor is vibrating and those vibrations are being transferred to the cab you've set up a feedback loop. Since the cone is isolated from the cabinet by the driver suspension the effect of the feedback loop isn't severe, but it's there.

Point of fact: Unless the cab is defectively constructed there's no such thing as mechanical coupling. That phenomenon can only occur if the cab walls flex, and the walls of good cabs don't flex. Even relatively flimsy cabs don't vibrate in the lows, they vibrate in the mids. If they vibrated in the lows they'd be unusable. All low frequency vibration of the floor is caused by the acoustic output of the cab. Therefore so-called isolation devices have absolutely no effect on floor or other room surface vibrations. However, if the floor is vibrating said vibrations can then be transferred back to the cab, and the head atop it, and stopping those vibrations can be worthwhile. But doing so doesn't require a high level of sophistication, let alone high cost. A bit of carpet will do the trick.

[quote name='davehux' timestamp='1350652037' post='1841799'] They say they want a single big speaker to share. [/quote]Bad idea. Hearing the monitors means hearing the mids and highs. Mids and highs are very directional, so each player needs their own to be in the 'sweet spot'. Hearing them also means a good EQ dedicated to the monitors is mandatory.

[quote name='bremen' timestamp='1350462921' post='1839075'] I modelled a 2by10 using Eminence Beta 10A in WinISD and however big or small I made the cab, however I tuned it, the power handling dropped to 20-40W between resonance and 100Hz. Should I have doubled their stated Xmax figure, or are they really this crap? Or is WinISD very pessimistic? [/quote]They really are this crap. Makes you wonder why Orange uses them, and charges what they do for them. The bad news is that the Beta 10 not only isn't unusual in its lack of output capacity, it's actually better than many OEM drivers.

[quote name='Rammsteinbrit' timestamp='1350404574' post='1838373'] Low is nearly on full [/quote]Doing that can cause both the speakers and the amp to reach their limits. Don't.

Most sources quote xmax one way, Eminence among them. One would think that it would be stated as a +/- figure, but it isn't.

+/-4mm is the same as 8mm peak to peak.

It's not the least bit unusual for a start-up company to find itself unable to keep up with the demand once the word gets out. If Alex was still taking full payment rather than just a deposit you'd have some valid concern. Since he isn't he's not I'd be patient, good things come to those who wait.

[quote name='4 Strings' timestamp='1349164721' post='1822473'] regrettably as I try to stay British whenever I can. [/quote]My Ashdown was built in Italy of parts sourced from China.

[quote name='bremen' timestamp='1348829790' post='1818774'] If you put them one either side of the drummer you'll get cancellations at various spots on the stage. Keep them together and they'll augment each other, not fight each other. [/quote]+1. To get the mids and highs to the drummer aim the lower cab towards him, the upper cab towards yourself.

[quote name='Damonjames' timestamp='1348347375' post='1812710'] if I was to run the same head through a orange 4x10 and 1x15 (rated 600 watts each) given perfect world scenario could you run said amp flat out or only to an output of 600 watts. [/quote]The Orange 410 is displacement limited (http://barefacedbass.com/technical-information.htm) to only 150 watts, the 115 to 100 watts, so a 1kW amp is massive overkill. This points out why you have to consider much more than just power ratings of both amps and cabs, and for that matter why this particular 419/115 combination is a poor one, as are most.

[quote name='Benplaysbass' timestamp='1348255161' post='1811591'] I have read online some people have just cut the wires going to it. This is an option I am thinking about, but does anyone know if I am likely to damage anything by doing so. [/quote]You could damage the amp, depending on the crossover topology. The safe method is to remove the crossover entirely and wire the woofer direct to the jack.

[quote name='bremen' timestamp='1348143350' post='1809907'] Doubling the power increases perceived loudness by 3dB, noticeable only in an AB test. Add to that the fact that most amps that deliver (for example) 100W into 8 ohms will only deliver about 160-180 into 4, so it's even less than 3dB. [/quote]+1. Most players assume that power is linear with respect to perceived loudness. It isn't. To double perceived loudness requires ten times the power. What you'll hear going from an 8 ohm to 4 ohm cab, assuming the cab can make use of the increased power output from the amp, is barely perceptable. And then there's the matter of driver excursion. The average bass cab can only make use of 1/2 its thermal power rating before reaching its mechanical limit, so putting more than, say, 250w into a 500w rated cab won't get you any more output at all. In the vast majority of cases insufficient volume isn't caused by insufficient power, it's caused by insufficient speakers to handle the power available.

[quote name='far0n' timestamp='1348091394' post='1809320'] Why is that? [/quote]Because the notion of 'getting all the watts out of my amp', as wrong as it is, pervasively dominates the marketplace. In those cases where a manufacturer offers both options 4 ohm outsell 8 ohm about 3 to 1. So if a manufacturer decides to offer only one or the other in most cases it's 4 ohm.

[quote name='Kong' timestamp='1315969397' post='1372737'] There's a big difference between Pre-Amp - distortion and power-amp - distortion aka clipping. If You drive Your power-amp into clipping You will destroy Your speaker. This is why it is dangerous using a small amp (let's say 100 watt) into a big cab (let's say 500 watt). If YAou have Your preamp maxed out, it will start clipping. If You don't hear this, the speaker will get killed by thermal issues. Pre-amp - distortion, carefully amplified with the power-amp, will add harmonics to Your sound, compress it a bit and makes it richer. [/quote]Clipping is clipping, no matter where in the signal chain it occurs. That includes in the drivers; one reason why guitar drivers have a very small xmax is so they'll clip at relatively low signal levels. And if clipping hurt drivers guitar players would swap them out after every set. Only tweeters are inherently at risk with clipped signals, due to the higher percentage of harmonics, and that's one reason why they aren't used in guitar amps. Required reading: [url="http://forum.qscaudio.com/forum/viewtopic.php?f=29&t=2736"]http://forum.qscaudi...php?f=29&t=2736[/url]

[quote name='Mr. Foxen' timestamp='1347915958' post='1806704'] The Kappa pro 15 is a whole bunch less suited to the purpose than the Kappalite, different driver. Handles loads less power. [/quote]+1, about 75% less. Output is limited by driver excursion, not the thermal power rating. With 1/2 the excursion of the 3015 the Kappa Pro can actually make use of 1/4 the power, giving 6dB less output. That translates to needing two Kappa Pro loaded cabs to equal one 3015.