Serious sub

[Bud Barnez]

I scooped this sub on eBay some time ago, and finally moved into a place that can handle it.

It truly is brutal. The drive unit is a 15" Focal Audiom, and the amplifier a Krell KSA 150 (or 250 I'm not sure), tranny is Pilton 1508 VA 700, and the caps are monstrous, the size of large beer cans - the lights dim noticably when it's powered up.

I bought it from an AV install company who were asked to remove it by a customer who they were doing an install for, apparently it was commissioned for Elton John who left it behind in the house he owned in a posh area of London - looking at the components, I can believe it. There isn't a makers marque on it, and looks like it's custom made; I reckon the the brief must have been cost no object.

It sits as a coffee table, the size is about 1.3m x 1m x 0.45m.

Construction appears to be in two layers with extensive bracing. The internal layer is 1" mdf, and the outer another 1" in some kind of dense material that I think maybe phenol (sp). It then has polished piano black panels on all sides with toughened glass top.

I don't know how much it weighs but you need three strong people to lift it, I would guess the weight to be 200kgs it's the most ridiculous piece of hi-fi I have. I had to abort my first attempt at picking it up as it wouldn't fit in my car - had to go back with a van!

It has no crossover built in, so I bought a BBS analogue crossover which I usually have set coming in at about 70Hz. Needless to say it goes low. I have sash windows and when playing loud they rattle in their cages, and the radiators in the central heating system act like transmitters sending base all round the building. I tested sine waves down to about 12Hz, I can't hear it but everything shakes, and it actually makes me feel physically sick if I sit close to it! I reckon it churns your insides.

I don't know how people get pictures embedded in their posts but I've tried to attach some pics - I hope they give you guys some inspiration, plus would like to know what people think or if anyone knows anything about it or it's history:

[Mikey p]

That's a 15VX driver with 6mm Xmax. I assume you were testing it in a fairly small room?

http://www.kemt.fei.tuke.sk/predmety...Audiom15VX.pdf

[Bud Barnez]

Yep - thats the driver. I was surprised at the low excursion of the driver.

Room is fairly small (approx 4m x 7m)

In normal use its actually quite subtle, a bit too subtle I think. My preamp bas one set of balanced outs and one set single-ended - I use the balanced outs for the power amp and the single ended outputs to the crossover, so the signal level on the single-ended output for the sub is probably too low for ideal operation. I compensate by adjusting up the gain on the crossover which is usually set to add around 5dB.

Would I be better off splitting the balanced out from the DAC directly to the crossover so it's taking a full level output signal? Problem is then I'd have to adjust two volume levels for a uniform output from main speakers and sub?