upgrading woofer in my econowaves : checking out the Eminence Delta 12LFA
Hi,
I've been greatly enjoying my econowave speakers this last year, but always thinking I could do better with the woofer, which was an inexpensive Ebay PA driver with very little information available about it. I could never get it to match up with the d220ti cleanly at the crossover point, and ended up using a simple first order LP as the best tradeoff.
Without buying the new drivers to measure first hand I've been playing around with software tools to using published data and a bit of guestimation.
Before I go the next step of actually buying drivers and bits, thought I'd post my ideas here to see if I'm heading in the right direction..
To keep using the existing MDF enclosures (which I quite like) I'm limited to 12" woofers that play nicely in 120.6L (or less) with 2 (or one if I block a port) 10cm bass reflex ports.
Also theres the actual size of the woofer rebate and hole fitting to take into account, some of the drivers which look really good would mean extensively reworking the rebate and repainting (the Beyma 12BR70 for example, which otherwise looks like it would be great).
The Delta 12LFA looks like it matches very well, and will drop in the existing cabinet with minimal modification. The T/S parameters indicate it will play very well with the 120L box I have with the existing ports.
I dont have a 12LFA to measure, so I used SPLtrace to make a .FRD file from the PDF specs, and used that with speaker workshop and the d220ti+PH612 measurements I already have. This is where the fiddle factor comes in, I didnt calibrate my measurements(they were relative to the woofer response done in the same session), so I've just scaled up my FRD response to look similar in magnitude to Seleniums published one... I'm also hoping the L-PAD adjustment makes this point largely moot anyway as it can be "dialled in".
With Speaker Workshop, bouncing around variations on the Ewave high efficiency crossover, etc, I've settled on a using a 3rd order LP so as to get a fairly steep cuttoff to tame the huge bump at 2K while stil keeping the rest of the response fairly flat.
I've also lowered the cuttof point on the HP so to suit.. (with a bit of smoothing), gives what looks like an OK result.
If I do get the driver I'll measure everything and may have to adjust values to suit reality, but I'm hoping it won't be too different and I can get results in the same area as these estimates with some component value tweaking:
LP : 1500Hz (3rd order)
HP : 2500Hz (I think??)
info from Eminence:
http://eminence.com/pdf/delta-12lfa.pdf
Photo of one of the actual speakers:
