m-db
621 posts
They are tuned to the room through, Putty Pinching. Perfect integration without digital correction.. Pretty cool actually. 50-100 sand bags worked the best. The slot glued to the floor so to speak.. Ceiling will work too. :-)
oldhvymec, this seems an interesting technique which I know nothing about. Is it possible to explain a bit further or provide a reference or a link to this method?
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There are two approaches to passive radiators. One is a standard cone with a suspension added and conventional butyl rubber surrounds. Then there is a lighter mass version. The cone is lighter and so is the suspension. Normally the surround is foam too. There is a reason.
With a light moving mass the key is to add enough fixed weight to match the port frequency's lowest point with the space and active drivers used. Now to go below that point we add non hardening putty, (Mortite putty is the best) to the point of BOOM in the room.
Now comes the tricky part. You remove mass (putty) the size of a peppercorn at a time until the boom goes away. Your single sub unit has been added and blended to the perfect (Q)uality, with your amp, your mains, you cables and your room. NO electrical correction of any kind, digital or analog. Purely mechanical, just like me.
Now correct your room mechanically. Passive materials. You absorb the bass, you let the bass escape, you control the bass with (Q)uality control. Now you can add just slight correction, vs full blown DSP room killing correction.. I hate it.
Direct coupled subs that use active crossovers and (Q)uality control are pretty amazing. Very close to a DBA servo sub system, SQ wise.
One of my bass system uses 10-20 drivers, there is a lot of cubic inches of cone material, but perfectly controlled and tuned to any gear, cables or room. GRs servo subs and my SAT Bass columns direct coupled. No crossovers.. There is a small set on my Virtual page..
It's my ways, they work very well. I like the VMPS columns. I wish someone would make them again. I need 20 acres, a wearhouse, and a mule..
Regards