Santiago Mods

[GM]

I was starting to wonder if the 411 had any redeeming value which begs the question, what was Altec thinking when they designed it? Nowadays, I am not motivated enough to build custom cabinets. I think I will remove the 811 horn and reseal the Santiago, then biamp with the 511.

I have seen some posts recommend at least a second order slope (12db). Why not flatter (or steeper)? I will play with various slopes and xover frequencies until I get the sound I like but would appreciate any thoughts on this aspect.

Greets!

The 411 was designed to meet the performance needs of the times same as any product, yet still somewhat backwards compatible and why it?s suitable for a large vented alignment, especially one driven by a high output impedance that dictates an acoustically large cab tuned to Fs if max LF BW efficiency is to be realized.

To mod the 878 cab for a 511, the easiest is to seal off the horn cutout and flip it upside down to keep vertical acoustic offset to the practical minimum with the 511 on top. For this reason, just perching the 511 on top isn?t technically a good plan unless the listening distance is far enough away for the horn to appear as being very close acoustically to the woofer.

Perching the 811 on top of the 511 has some merit in theory as Cal Weldon has done on top of a pair of A7 cabs. Since the horns must be attenuated so much due to the 411?s relatively low efficiency though, the extra XO point may not be worth it unless you need the extra HF horizontal dispersion it affords.

Since the cab will be a bit larger [net Vb] acoustically, it will have a slightly lower Qtc [higher F3], so will in theory have a bit ?tighter? LF response, though without an A/B comparison it may not be obvious due to the room?s acoustics contributing so much to a speaker?s perceived tonal balance.

?Textbook? 2^nd order slopes are a good compromise between complexity, power handling [driver protection] and distortion plus long before TD alignment became the ?next big breakthrough? in speaker design it was found that even order slopes makes it easy to design in time alignment within the ? WL standard empirically determined early on in multiple speaker system design by simply reversing the HF driver?s polarity, though of course with digital delay one can easily/quickly align most any oddball/extreme offset layout, slope order.

The big problem though is that for it to work properly acoustically there must be at least an octave of ?flat? BW on either side of the XO point, which severely limits its location without carefully matching components and/or using some form of EQ.

WRT woofer/horn combos, there?s the added problem of the point source [woofer] having a 90 deg phase lag Vs a compression horn?s, so this must be either accounted for by proper vertical offset and/or use an odd order on the horn and even order on the woofer.

With the Rane then, you should have no trouble dialing in an XO, horn CD EQ, timing offset [TD] that yields whatever horn vertical lobing offset is required to ?beam? the HF to your ear height/whatever, so no need to be limited to any ?textbook? solution, though spacing it up off the floor as much as practical to keep from needing excessive lobing is normally a good plan plus getting the woofer up to chest height can add a bit of the visceral impact of a live event.

GM