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jessie.dazzle wrote:

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).

Presumably that the McCauley drivers are fine I think would be the very ultimate ULF channel. The 100 Watts of M1.1 is a bit tricky as Vladimir very conservatively grade them as 100W. Generally in what I seen Lamms are able to pump more than this. I did not measure where they clip but it felt as they are more powerful than some other amps rated at 100W

jessie.dazzle wrote:

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.

I am bit skeptical for use basement as a rear chamber in my case. My floor is suspended and I do not want any bone vibration take palace when ULF is working. This is why I am trying to put my ULF in another room that does not share the same suspended floor as my listening room. I have Sunfire cub sub that is horrible sonically but able to pump very high pressure, placing it in deferent locations is it very easy to model what and how will vibrate. This is what I will be experimenting when my midbass project will be over. The only viable use of basemen, at least in my case would be if I make woofer sitting in some kind of sealed pipe that goes from basemen floor to basemen ceiling and exhaust into the listening room, but decoupled from the listening room’s floor. I am contemplating it but cutting two 20 holes in listening room floor would require me to be absolutely confident that it is what I want. At this time I do not have this confidence as I am still do not have a clear visualization of what kind ULF sound I would like to make. I do know very precise what I would NOT to have in lowest octave but it is not enough for me.

jessie.dazzle wrote:

I've never seen the cones go beyond maybe 3/16" total excursion …

That is very good. I do not like the drivers that excurt too much. What kind outer suspension it has, is it rubber? The web site does not say anything about it. Anyhow, the amount of pressure McCauley does is not a key factor. I think the key factor would be the degree to which the driver is able to decimate the LF pitches.

jessie.dazzle wrote:

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.

Actually it was not increase the moving mass but using much softer suspension (what I was told). If the subject were only about mass then we can do it today with any of the Auras. At that time North Creek had access to made-to-order inner suspension (spider) that was much softer. This combining with the fact that it was the only one 18” woofer with underhang motor and the fact that it has cloth outer suspension in my view made the driver very exclusive.  I have 4 of my Auras but they I think stock versions. I need to measure them to see what they are. But I still will try my arrays of the 10” scan-speaks first. Anyhow, this ULF chals will be a very interesting thing to experiment during the long NE winter….

The Cat

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