OK, here's my analysis of why there was a problem:
--Alembic F-1X tube preamp
Naturally big bottom - that should be ok but...
--Behringer Multi-com (compressor)
Increased sustain on high overtones increasing likelihood of blowing bulbs.
--Aphex parametric EQ (5 band, used to put in mids and roll off lows)
EQing in midrange does certainly increase the risk of clipping, especially as the midrange peak demand is higher during attack, especially when slapping.
EQing out lows at 40Hz and below means you're losing out on where the Acmes perform best. With a ported cab you get maximum LF power handling around the turning frequency - on the Acmes it's 30Hz, on most other cabs it's 40-55Hz. Because the port is taking over most of the output the cone excursion rapidly decreases. If there was no port cone excursion would quadruple every octave you descend. The port counteracts that and this means that at about an octave above the port tuning frequency excursion reaches a peak.
The bass content of any note is mostly from its first and second harmonic. If your cab cannot put out the first harmonic due to it having very little response there, the second harmonic has to be louder to sound as bassy. So if you remove the first harmonic with EQ then all the demand happens in the second harmonic. In the case of an Acme, EQ out the low B first harmonic (aka fundamental) which it is very good at reproducing and has huge power handling at, and all the power has to go into reproducing the second harmonic where the power handling is lowest. And bam, you run out of excursion.
--Stewart World 2.1 (in stereo)
--2 x B2s (4 ohms)
Good amp. Good match of power. Don't know how good the Stewart's limiters are - some limiters are much smoother than others and protect from extra HF energy blowing the bulbs.
No highpass filtering though, which is a shame. Then again you're already EQing out the lowest lows but as I said above that's what's causing your overexcursion problems.
We always had PA support and the rig was purely for stage monitoring purposes. The band could be loud at times, but not deafening by any means. For EQ, I would generally dial in somewhere around 250 - 600 Hz for mid bump and roll off lows beginning around 40 Hz. And I would generally leave the crossovers up to get more midrange and top end bite. Bulbs blew fairly regularly and woofers were almost permanently creased.
To put things in perspective, I played a gig on Saturday with the Acme rig (PLX 3002 and two Low-B2s) carrying the whole house sound, my drummer was unmiked but he has a Vistalite 'Bonham' kit with 26" kick which is insanely loud, and we're a kind of alternative rock band with a large dose of funk and ska. I was using no EQ or compression on bass or amp. I never ran out of headroom and the rig punched through the mix loud and clear.
I don't think the Acmes are as a good choice when you have a PA with subs because they put out more bottom than many subs and multiple LF sources tend to interact in unpredictable and often bad ways. However, I'd put money on you being able to hear yourself loud and clear if you used my bass and rig without changing any settings in your band - actually, I should say that is subject to having guitarists and keyboardists that understand the importance of keeping out of the sub 200Hz area - I forget what a pain that can be...
It's taken me years to get my head around why Acmes work great for some people and less well for others. The problem is that many of the intuitive things you did to help the situation - compression, mid boost, low cut - actually made things worse!
It's also a case of horses for courses - deep bottom and smooth mids are obviously not what you wanted as you're happy with your Schroeders which have very little sub 100Hz output and a big hump in the mids.
Alex
), I figured I might as well get a speaker cab voiced inherently that way in the first place so I could crank it and not worry. I've never looked back!
