Damaging speakers in open backed cabs

[Ancient Mariner]

As yet I don't have a true bass amp, but I do have a Pignose G40 fitted with a Hartke 10" ali coned speaker. The Pignose cab is small - very small - and completely open at the back. It sounds OK at low volume, but there's a suspicious fuzzy rattle if things get turned up a little.

So tell me - are open cabs a no-no for bass use? I suspect I've exceeded Xmax and possibly Xlim for this speaker.

[MythSte]

[quote name='Ancient Mariner' post='751416' date='Feb 19 2010, 10:17 PM']As yet I don't have a true bass amp, but I do have a Pignose G40 fitted with a Hartke 10" ali coned speaker. The Pignose cab is small - very small - and completely open at the back. It sounds OK at low volume, but there's a suspicious fuzzy rattle if things get turned up a little.

So tell me - are open cabs a no-no for bass use? I suspect I've exceeded Xmax and possibly Xlim for this speaker.[/quote]

I dont know the science exactly, i suspect you know more than I do in fact! but yes, Generally speaking open backs are a no no for bass, and you would have to push it a lot harder to get the volume so you may well be damaging the speaker.

[Bill Fitzmaurice]

[quote name='Ancient Mariner' post='751416' date='Feb 19 2010, 05:17 PM']So tell me - are open cabs a no-no for bass use?[/quote]An absolute no-no.

[skankdelvar]

As you rightly note, things can get very iffy if you turn the wick up. Feasible at [i]very[/i] low volumes, but not at the levels of output one would need to get over a drummer.

IIRC much of the bass on Nirvana's Nevermind went through a JBL-loaded Fender Twin. But that was in the studio and a long time ago.

Edited February 20, 2010 by skankdelvar

[Phil Starr]

Yep you are right. At low frequencies the cone has to move further to achieve the same velocity so excursion becomes important. Without knowing the details of how excursion is limited in the Hartke's I couldn't say whether you will damage the speakers but I personally would look for something else. Generally speaking open back cabs won't go low enough for satisfactory bass as they would need to be huge (4mx4m) to reproduce bass. In addition the spring of air trapped in the cab helps control bass excursion as you have seen.

[Ancient Mariner]

Thanks Guys - I'm sure this is the problem. I may well try to pop the driver into a small sealed cab in case it's not been killed, but I don't have too much hope.

FWIW I vaguely remember playing bass through an AC30 in my teens, and it 'worked' but was flubby and woolly (I assumed because of the bass and the flatwounds, rather than the amp). This was obviously the wrong way to go about things.