GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Horn-Loaded Speakers
In the Thread: Macondo’s lowest channel.

Post Subject: ULF experience: Drivers & power considerations cont'dPosted by jessie.dazzle on: 9/21/2010

Romy wrote:

"...I do not know anything about your LF section. What do you use and where does it crossed?..."

I have 2 ULF "boxes"; each has an 18" McCauley 6174.

The enclosures are sealed and each measures 14 cubic feet. They are made from 70mm thick concrete blocks.

Power is from a pair of M1.1 amps (100 Watts each).

Crossover frequency (set high until I get the mid-bass horns done) is 60Hz, 6 dB/Oct, and is for now done via a Velodyne SMS 1 (this is the only place I use an active crossover).

Since the last round of modifications to the system¹, I no longer use any electronic EQ for these channels. I never did use the phase correction feature, as the boxes are positioned such that I don't need it. This all means that the SMS 1 now serves only as a 6 dB filter. If I were not moving, I'd replace it with a simple passive crossover.

However, I recently bought a house in the US and will at some point be moving (its complicated). The house has a basement which might be exploited as a rear chamber. For this reason I am debating weather or not to move the ULF boxes, as they are extremely heavy. This is what's behind the questions in my previous post.

"...The McCauley 6174 looks like a good driver; I wonder how long the motor if this driver is..."

Their spec sheet does not give this information, however, this driver is capable of a full 2 inches of excursion, so the motor is certainly designed for long travel. They are intended for use in live public concerts; in the context of a home system, with the volume really turned up loud, playing deep bass, I've never seen the cones go beyond maybe 3/16" total excursion (at this point, small items start falling off the shelves in my neighbor's house). So it is fair to assume that for our purposes, the coil operates well within the saturated zone.

The 100 Watts per driver as supplied by the M1.1s is more than enough to get me arrested... I can only assume it has something to do with this amp's capacity to deliver high current. At some point I will compare them to a 1000 Watt class D amp that I have; It would be intersting to learn what, if any sacrifice this entails. If I could get away using the class D amp, I'd save quite a lot on electricity.

"...I kind of sorry that at my time I did buy the Leviathan woofer. It was 14Hz in underhang mode – those types of the drivers never will be available again…"

I once looked into this driver and ended up speaking with someone who was involved with their modification... According to what I was told, converting the Aura driver into a Leviathan involved loading on weight to increase the moving mass... I don't like this approach.

jd*

¹Changed drivers in the upper bass horns from 8 to 4 Ohms (using what I guess is a custom-ordered pair of Fane 8Ms in 4 Ohm), and added more damping materials between and behind all horns.

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