I was just looking at my Low B-2's drivers this afternoon, and I noticed that right where the cone meets the pleated surround there were little half-moon shaped. . . . well, I guess you could call them scrapes or slight gouges. I am trying to figure out what could do this? I am almost convinced that the speakers excursed all the way to the grill and rubbed against that. But that's crazy, right? So, the question is: Are there a variety of ways that cones can crease? I have seen first-hand bad creasing, but could these new marks be another type of creasing?
Acme's are known to have rather stiff surrounds when new, and require a break in period to loosen up before being pushed hard. If you crank them too hard too soon, they will crease the cones. In other words, the cone will flex instead of the surround.
Sounds like standard speaker-creasing from over-excursion. Doesn't have to hit the grill for this to happen, its what happens to the cone when it bounces farther back and forth than it is designed to. Its the result of running too loudly with too much low end, the cones just can't take it. The result is a small amount of distortion coming from a creased speaker. Over time, the creased areas will get weaker, and the distortion will become more and more apparent. I've suffered this before, so I know what I'm talking about. After about 8 months of playing through creased 10's, it became unbearable and they had to be replaced (or you can get a recone).
It is indeed possible to crease Acmes, even ones that have been properly broken in. I've been through a few of them in the last while and as Eric says overexcursion will do it. Hitting the grilles didn't factor into the equation in my case, but a little slapping and popping certainly did. Call Andy for replacements. He's excellent to deal with.
Mr 'Oddio', Do you know if it was your QSC or one of your valve amps that was driving the Acmes when the cones creased? Just wondering if the damping factor makes a difference or if it's just down to sheer peak power. Did you see any clip lights coming on? Alex P.S. Been doing some further investigation into 15"s and looking at Eminence's stock drivers I can see how a carefully custom-made one could produce the insane bottom of the El Whappo. A very clever design indeed, and like all the Accugrooves seems to use a relatively large cabinet volume to get the efficiency up but then keeps the weight down with cunning bracing, very nice plywood and (some) neo drivers (I'm guessing the latest weight drop is due to the mid-bass 12" in the El Whappo and Whappo Jr going neo).
Andy's replacement prices are quite reasonable... I've been told by a friend who creased all four of his woofers that Andy said that he has customers that have to replace their woofers as frequently as every few months...
Pics are going to be difficult as I had to be within a few inches of the cones to see them. Plus, they are that grey upon grey color that I know a disposable camera is not going to pick up. I bought the cab used, and the previous owner swore up and down that he conditioned it properly (he is a TB guy) I have an email into Andy and we'll see what he says. If it's affordable, I'll just replace the drivers. That aside, let's still hear what others have to say about creasing variations!
Thats astounding. I use an Acme B4 and B2. Played a bunch of outdoor gigs loud as heck with a 5 string and could hardly even see the cones moving....Had a sound guy tell me to turn down because I was screwing up his FOH mix on his EAW festival rig.
It's a pretty good bet that the combination of 1/. an extremely punchy bass (beech Wal), 2/. the DB750 which is plenty powerful with 2 Acmes and 3/. my propensity to slap and pop on a few numbers is what creased the cones. Nonetheless, Andy was excellent to work with and the cabs were back up and running in short order. Excellent customer service and a wonderful speaker, especially given the price. With the cost/watt nowadays I would not hesitate to recommend Acme.
Can also be done by slapping/popping with an 18v preamp (into 700W); this caused the demise of the original drivers in my B2. The bad part was I wasn't the one having all the fun
Well, Andy got back to me. I'll be getting some new drivers next month. He knew what I was talking about. Darn!
If you are creasing your drivers, it is because you are over driving them, for whatever reason. Get more cabs, or it will happen again for your playing style. $50 here, $50 there, eventually this will add up to real money. By then, you could have bought a 2nd cab a saved yourself the grief, shipping costs, and wasted time.
Call me crazy, but that would seem to indicate a systemic problem with the drivers. Or maybe it's just a systemic problem with the operators.
Interesting... I wonder if it was the ultra-low percussives from the slapping that caused the over-excursion? With your QSC you'd be filtering out sub 30Hz but the DB750 doesn't have anything to restrict the low frequency extension. I've noticed a dramatic difference in cone movement with having the filters switched on or off. Alex
Thanks Alex. I was aware that the lack of a 30Hz filter on the DB750 may have factored into it. Also I'm generally as careful as possible about ultra-low percussives epecially when slapping and popping (quite infrequently) but you never know. Andy did a great job getting replacement speakers up here so I'm not in a panic over it at all. I don't begrudge my Acmes a little downtime as they've been working quite hard over the last two years.
