Here's some pictures of the driver... Sold as 6.5" poly cone woofers, foam surround.
I have T/S specs but would really like to get some response charts to come up with a reasonable x-over. If anyone recognises these or has any ideas for a place to look for a response chart I would very much appreciate it.
Thank you and Regards,
Eric
I have T/S specs but would really like to get some response charts to come up with a reasonable x-over. If anyone recognises these or has any ideas for a place to look for a response chart I would very much appreciate it.
Thank you and Regards,
Eric
I had that problem 2 years ago
An old pair of Cerwin Vega 3 way 15" woofer PA speakers and a wife that gave the "do something with these or I'll burn them" concept. Since I had no T/S parameters on the woofers, I tested them for Fs with my multimeter and a free frequency program from the net.
Knowing that the original cabinets were dual rear ported for 40Hz--it gave me a clue. Measured the cabinet and had around 2.9 cubic feet of space. Removed the two horns and crossovers which returned 3.6 cubic feet. Did the isobaric face-to-face trick with the woofers to hit "7.2 cubic feet" but they did not like to be sealed. Added 2 inches of plywood on the back and bolted on a 18" passive radiator. My Fs measurement was 33 Hz so I guessed I could push the passive down to 22 Hz and get it rather even when corner loaded. Very simple to change weights on a passive radiator than cut port tubes.
So that would be my advice to you, use a meter to determine the resonant frequency of the woofers--the point that you have the lowest voltage is the resonant frequency. Get one of those passive radiators that allow you to tune without removing the radiator--tune it until smooth and you're done. If your tuning is really high (say 80Hz) that means you'll need a larger box which can be calculated with ratios. You can tune it by ear by using a frequency sweep but a Radio Shack meter runs around $40, get the calibration correct charts from the web and test away.
My wild guess sub box does 20 to 40 Hz +/- 2dB after messing around with placement and the passive radiator weights. Tuning a sub box to the room works very well so get a sound meter and have fun with it.
An old pair of Cerwin Vega 3 way 15" woofer PA speakers and a wife that gave the "do something with these or I'll burn them" concept. Since I had no T/S parameters on the woofers, I tested them for Fs with my multimeter and a free frequency program from the net.
Knowing that the original cabinets were dual rear ported for 40Hz--it gave me a clue. Measured the cabinet and had around 2.9 cubic feet of space. Removed the two horns and crossovers which returned 3.6 cubic feet. Did the isobaric face-to-face trick with the woofers to hit "7.2 cubic feet" but they did not like to be sealed. Added 2 inches of plywood on the back and bolted on a 18" passive radiator. My Fs measurement was 33 Hz so I guessed I could push the passive down to 22 Hz and get it rather even when corner loaded. Very simple to change weights on a passive radiator than cut port tubes.
So that would be my advice to you, use a meter to determine the resonant frequency of the woofers--the point that you have the lowest voltage is the resonant frequency. Get one of those passive radiators that allow you to tune without removing the radiator--tune it until smooth and you're done. If your tuning is really high (say 80Hz) that means you'll need a larger box which can be calculated with ratios. You can tune it by ear by using a frequency sweep but a Radio Shack meter runs around $40, get the calibration correct charts from the web and test away.
My wild guess sub box does 20 to 40 Hz +/- 2dB after messing around with placement and the passive radiator weights. Tuning a sub box to the room works very well so get a sound meter and have fun with it.
Hi 18hurtz,
I already have T/S parameters for the drivers. The boxes are built to suit the drivers well IMO. I am looking for the driver response above ~200hz, not below
As AllenB said, might be time to start thinking about picking up a mic, on the other hand, I imagine for the price of equipment to get going down that route, I could pick up 4 dayton RS180's instead. We'll see, I'm not in a huge hurry to get this "solved."
Regards,
Eric
I already have T/S parameters for the drivers. The boxes are built to suit the drivers well IMO. I am looking for the driver response above ~200hz, not below
As AllenB said, might be time to start thinking about picking up a mic, on the other hand, I imagine for the price of equipment to get going down that route, I could pick up 4 dayton RS180's instead. We'll see, I'm not in a huge hurry to get this "solved."
Regards,
Eric
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