sunbeamgls wrote:I remember someone on the Linn forum who had built an extra wooden "stand" for their active Akubarik modules - effectively a separate replica of the back of the Akubarik cabinet standing just behind the speaker - the link cables from the module to the speaker cab were long enough to allow for this. It would be interesting to hear the effect of that change - it will affect the behaviour of the cabinet and the electronics, I expect.
There are 3 of the below up each side of a 350 module (they are mounted with the rubber bush horizontally oriented):
350Bush.JPG
At the bottom of the module (below the mains socket) there are a couple of the same rubberised bushes that support the weight of the module, so in that case they are vertically oriented and they permit the module to move with respect to the base plate. On mine, the module was actually contacting the foot plate (though I'm told that isn't a problem) so just because I was in there anyway, I ordered various thicknesses of M6 shimming washers (they can be bought from on-line bicycle parts stockists) and lifted the modules up a tiny fraction (just to create the tiniest of gaps; you can just slip a sheet of thin paper in the gap) and then I removed 4 of the above pictured side mounts (leaving only the two at the top).
The idea came from finding out that the Exakt variants only use the bottom two vertical ones and 4 horizontal mounts (two on each side) and they've facilitated transit screws in the middle holes (if I ever sell my ones, I'd have to refit all the mounts before moving them or the modules would be in danger of thrashing about during transit).
Anyhow, the results are indeed quite interesting in that due to the modules mass (and thus its inertia) and it now having a far more compliant attachment (i.e. only the top two of the above shown mounts/bushes to attach it to the cabinet) when you play something with a big bass line and lightly touch the apex of the wood at the rear of the cabinet (i.e. the part just above the module) you can fell it moving very considerably, whereas if you instead lightly touch the apex of the module immediately below it, you can feel nothing at all. With them being so close (such a small gap) you can place a finger on both at the same time and again feel the massive difference.
We all know that rattling electronics about is a bad idea (back in the olden days, we used to place a bunch of magazines atop Karik, Kairn and Numerik boxes and it noticeably improved the sound) so consider how much more vibration they're experiencing when attached to the back of a 350! So yes, it did make a difference, but on the flip side, I've also reduced the effective mass (and thus inertia) of the cabinet (it's no longer partially acting against the module's mass; the energy is all being dumped into my poor old upper bushes) so the speaker moves more (thus the bass is more able to modulate the outputs of the higher frequency units). As I have a springy floor, I was concerned that the latter differences might overshadow (in a negative way) the benefits gained from removing some of the energy that was acting on the electronics and yes, on balance, I think the system sounds best the way it now is. Of course, when the energy stops (i.e. the bass note stops) the cabinet movement might now also be stopping faster, so perhaps that - as well as the more stable environment for the electronics - also partially contributes to why I prefer them as they now are?
Of course, another downside is that the poor old wiring loom (for which there is a big recessed channel in the Exakt modules, but not so in the 350A modules) will also be taking more of a punishment (as indeed will these Molex connectors that connect same to the boards within the modules) but it's surprising how much mechanical 'worrying' these things can take. One thing that happened (long before I did the above modification, back when I changed all the crossover boards from Artikulate to Klimax ones) was that one of the wires fell out of one of the Molex crimps (from memory, the one to an upper bass unit) so that was a pig to fix (I ended up doing it with long nosed pliers and then soldering it) as was replacing the busted fan (and it wasn't me who busted it) but that is yet another story!
Bri
Notes:
I should add that I'd very strongly not recommend anyone tries any of the above experiments as if you are not already familiar with how to remove/replace the modules (preferably by first practising on somebody else's 350As) you will likely run into trouble. Fortunately, my previous job involved working on tricky assemblies, so I managed to do it without damaging anything (other than my reputation, that is).
Also note that each bracket is individually bent (at the factory) to get the modules to sitting in the correct place (so not squint, or touching one of the sides).