This is just an area I can blab on about stuff without it using up bandwidth in the threads 
Hopefully someone will find it interesting or useful.
Tony.
Hopefully someone will find it interesting or useful. Tony.
leaks are stealing my bass
Posted 13th September 2009 at 01:06 PM by wintermute
Updated 25th November 2009 at 12:11 PM by wintermute (added to speaker category)
Updated 25th November 2009 at 12:11 PM by wintermute (added to speaker category)
I've long known that the boxes for my current three ways are leaky, more than likely incredibly leaky, but I've never bothered doing anything about it because I intended to build some new not leaky cabinets. Well I haven't and it is probably going to be a while before I do, so today I decided to check the impedance curve for the woofer in box. Thanks to Mick (prickears) for his quest to get to the bottom of his 80 Hz suckout I am finally doing something about my leaks!
The design goal (when I changed to vifa 10" drivers from the original 12" plessey's) was a box tuning freq of about 34Hz. When I measured the impedance today for one of the boxes, the tuning freq was in fact about 30Hz much lower than intended and when modeled with that tuning freq, has a very droopy response starting to roll of from about 220Hz, though the f3 is only 2HZ higher than the inteneded model at 36Hz..
So It looks like one of the diy tasks in the comming weeks will be attempting to get the boxes sealed and re-check the impedance curve.
Apart from that little distraction, I cut a few extra pieces of veneer for the bottoms of my MTM cabinets, I originally wasn't going to do them, but decided it was a good idea to seal the MDF, and also it was the best place to start in case I screw up The two pieces are currently flattening (using the 90% water 10% glycerine in a spray bottle method) Hopefully next weekend should finally get some veneer on the boxes!!
Tony.
The design goal (when I changed to vifa 10" drivers from the original 12" plessey's) was a box tuning freq of about 34Hz. When I measured the impedance today for one of the boxes, the tuning freq was in fact about 30Hz much lower than intended and when modeled with that tuning freq, has a very droopy response starting to roll of from about 220Hz, though the f3 is only 2HZ higher than the inteneded model at 36Hz..
So It looks like one of the diy tasks in the comming weeks will be attempting to get the boxes sealed and re-check the impedance curve.
Apart from that little distraction, I cut a few extra pieces of veneer for the bottoms of my MTM cabinets, I originally wasn't going to do them, but decided it was a good idea to seal the MDF, and also it was the best place to start in case I screw up
The two pieces are currently flattening (using the 90% water 10% glycerine in a spray bottle method) Hopefully next weekend should finally get some veneer on the boxes!!Tony.
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