Omni 15 midrange driver farting

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Alexander Eddy
Posts: 16
Joined: Fri Feb 09, 2007 7:52 pm
Location: Australia

Omni 15 midrange driver farting

#1 Post by Alexander Eddy »

Halfway through my Omni 15 build, I happened upon an already built 15 Tallboy on facebook marketplace at a price I couldn't resist. Got it home and the first thing I did was pull out the existing Kappa Pro 15 (non LF version and a terrible bass driver - no wonder the previous owner didn't like it), and replaced it with a 3015lf.

Driving it hard (a genuine 500w into the 8 ohm load), I found the first thing to distort is the midrange driver. A fart kind of sound. The sound went away if I dialled the bass eq back on my bass. With a thinner tone I could driver the volume harder and the mid got louder without farting. The more low end in the signal, the sooner the mid starts farting.

Is this normal? If not, what should I go looking for? I'm guessing check the crossover for the right components? It's an older build with an alpha 8 midrange - is there a reason the Alpha 6 is now specified in the plans?

Anyway, great sounding cab that I'm sure is going to cut well through the mix while having no shortage of low end. I'm quite keen to finish the half built one I've already started. Two has to be even better.

Bruce Weldy
Posts: 8209
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: Omni 15 midrange driver farting

#2 Post by Bruce Weldy »

Sounds like a crossover issue....

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210

"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

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Bill Fitzmaurice
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Posts: 28430
Joined: Tue May 02, 2006 5:59 pm

Re: Omni 15 midrange driver farting

#3 Post by Bill Fitzmaurice »

Yep, the bass control should have no effect on the signal to the midrange driver, unless boosting the bass causes clipping. With on board EQ that clipping could occur in the on board pre-amp, in the amp pre-amp, in the amp power amp or in all three.
The Alpha 6CBMR did not exist when the original version of the Omni came out. It has better highs than the eight inch.

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