Headroom question.

[Phil Starr]

[quote name='Dan Dare' timestamp='1509029092' post='3396168']
Don't 4 5" speakers have exactly the same surface area as a single 10"? Area of a circle is Pi x r squared. So 2.5 x 2.5 x 3.142 x 4 = 78.55, the same as 5 x 5 x 3.142.
[/quote]By and large for the same excursion the surround needs to be the same size for both sizes of speaker. So the cone of the 5" speaker is usually nearer 4" and the 10" speaker 9" very roughly.

[Dan Dare]

Interesting. I have several PJB 4x5 cabs and one of them is more than the equal of any single 10 I've come across in terms of weight and volume. They do take some driving, however. They're not very efficient and soak up power but they can give it out when fed enough juice.

[TheRev]

[quote name='Phil Starr' timestamp='1508797560' post='3394557']
Sorry it's almost certainly your speakers. Sure they may be able to handle 250W but that is their thermal handling, They aren't going to handle the excursion at lower frequencies, as Bill has pointed out you have something smaller than a 10" single driver in effect. Your options are to roll off the bass, turn your amp down, use some compression, perhaps a limiter which will reduce the peaks, go through the PA or buy another or different speaker.
[/quote]

You're probably right. Much as I love the MAS45, I've always had this niggling feeling that I really should have bought the bigger brother MAS46 which is more suited to louder stage volumes.

Having said that, the 45 works great on 95% of gigs - it's only when we have difficult room acoustics/quick change over/inattentive engineer that I get the E bottoming out.

Edited October 28, 2017 by TheRev

[TheRev]

[quote name='Dan Dare' timestamp='1509120411' post='3396834']
Interesting. I have several PJB 4x5 cabs and one of them is more than the equal of any single 10 I've come across in terms of weight and volume. They do take some driving, however. They're not very efficient and soak up power but they can give it out when fed enough juice.
[/quote]

This has been my experience also. My 4x5 has been a godsend and the most capable cab I've ever used for double bass (though obviously I'm am pushing it a bit hard in some situations).
There's more going on in bass cabinets than just driver surface area. The designer of my cab talks about the note 'envelope' and how a cabinet that can reproduce how each note blooms and decays will sound clearer (and therefore subjectively 'louder'?) than a cab that doesn't.
I don't pretend to understand the technical reasonings behind all of this, but I have used cabs (usually 4x10s or 8x10s) at festivals where the notes all seem to run together, with the result that I can't really hear what I'm playing. The instinctive reaction in this situation is to turn up the volume, but that just gives you louder mush. My 4x5 sounds clearer and more articulate to my ears, so perhaps it doesn't need the cone area/SPL to get its point across.

[Bill Fitzmaurice]

[quote name='TheRev' timestamp='1509176748' post='3397111']
I have used cabs (usually 4x10s or 8x10s) at festivals where the notes all seem to run together, with the result that I can't really hear what I'm playing.. My 4x5 sounds clearer and more articulate to my ears
[/quote]That can be chalked up to the better upper midrange response and dispersion of the smaller drivers. It's why some cabs are now made with larger woofers for the lows and smaller midrange drivers for the mids. PA and hi-fi cabs have used that arrangement since the 1950s. Bass cab manufacturers, and bass players, are slowly coming around.

[GreyBeard]

[quote name='Bill Fitzmaurice' timestamp='1508612969' post='3393382']
No. You need to double the power to get 3dB of additional headroom, which isn't all that much. Besides, nine times out of ten what you describe is caused by your speakers running out of excursion capacity.
[/quote]

This is what I'm thinking, your speakers don't have enough XMAX. Try rolling of some bottom and the farting should stop.

Edited November 3, 2017 by GreyBeard