mhardy6647
Lunatic Member
When he was in 10th grade, our son did a high-school science fair project based around the venerable PartsExpress 269-469 4" fullrange driver. He measured the T-S parameters for the drivers and designed "optimal" vented and sealed boxes for them based on the measured parameters. He built the boxes and compared the frequency response (as best he could) with a Radio Shack SPL meter (the latter a "secret Santa" gift from AK member Toasted Almond some years back).
The vented enclosure was more pleasing overall, so the pair (which were the same internal volume, interestingly) were both converted to vented boxes. They were on long-term loan to a Bottlehead friend in MD for a couple of years (due mostly to my sloth in retrieving them). I picked them up a couple of weeks back and brought them back to MA -- somewhat ironically, since the aforementioned son is now in college in MD (but with other speakers)!
Having the house to myself this AM (Mrs. H is at a meeting at our church), I spent a little quality time with these little guys and snapped a few photos. If you have never heard one (or more!) of these amazing little drivers... you should seek some out and listen. They are really amazingly satisfying fullrange speakers. They are, empirically, capable of more bass in a larger enclosure than the "optimal" (critically damped) enclosures shown, but they still sound really good. They are also really efficient; fine for low power SET amps.
They also lend themselves nicely to line arrays... if you've never seen the link(s) below... take a look sometime!
http://ratch-h.com/tweak.html
http://ratch-h.com/pa-speaker.html (the 269=469's were original 95 cents, later reduced to 69 cents on closeout!)
http://ratch-h.com/69centwonder.html
A similar looking (if not identical?) driver appears to still be available from Madisound (albeit rather more expensively):
http://www.madisound.com/cgi-bin/index.cgi?cart_id=5017227.9823&pid=915
The vented enclosure was more pleasing overall, so the pair (which were the same internal volume, interestingly) were both converted to vented boxes. They were on long-term loan to a Bottlehead friend in MD for a couple of years (due mostly to my sloth in retrieving them). I picked them up a couple of weeks back and brought them back to MA -- somewhat ironically, since the aforementioned son is now in college in MD (but with other speakers)!
Having the house to myself this AM (Mrs. H is at a meeting at our church), I spent a little quality time with these little guys and snapped a few photos. If you have never heard one (or more!) of these amazing little drivers... you should seek some out and listen. They are really amazingly satisfying fullrange speakers. They are, empirically, capable of more bass in a larger enclosure than the "optimal" (critically damped) enclosures shown, but they still sound really good. They are also really efficient; fine for low power SET amps.
They also lend themselves nicely to line arrays... if you've never seen the link(s) below... take a look sometime!
http://ratch-h.com/tweak.html
http://ratch-h.com/pa-speaker.html (the 269=469's were original 95 cents, later reduced to 69 cents on closeout!)
http://ratch-h.com/69centwonder.html
A similar looking (if not identical?) driver appears to still be available from Madisound (albeit rather more expensively):
http://www.madisound.com/cgi-bin/index.cgi?cart_id=5017227.9823&pid=915
