cone driver or polygraph on kappa 8/9

[kappa7krazy]

Has anyone replaced their polygraph driver in the kappa 8/9 with the midbass coulpler from the renniassance 90. If so what were the results?
On the Infinity product support page, it lists the midbass coupler as a replacement for the polygraph(since it is no longer available). Wasnt the crossover designed specifically for the polygraph? This is the only driver I dont have for my home made kappa 8's and I was wondering if it is better to go with a used pair of polygraph drivers or get a new pair of the midbass coupers. Also, looking at some of the listings for the polygraphs, it seems they might have a problem with the voice coil getting deformed. Are the polygraphs very delicate? Are they easy to over drive? TIA, Brian.

 

[rroobbcc]

I have the the Ren90 mid-bass in my 9 Kappas. I had one damaged Polygraph and for a while only replaced the one damaged unit. I could not not hear any difference between the two. The opening for the driver needs to be enlarged for the Ren90 driver to fit, but I used a file to remove just enough material in the right places so that I can still go back to a Polygraph later. As you want to build cabinets, it should be a non-issue. I do intend to go back to the Polygraph eventually, for originality's sake, but sonically I have no concerns.

Rob

 

[kappa7krazy]

Thanks for the response. I am glad to hear that there is no difference in sound. Could you tell me if polygraph driver did have its own enclosure within the cabinet?

 

[rroobbcc]

Yes it does. There is basically a 6 or 7" (probably 7") tube behind the driver from the front to back of the cabinet, essentially creating a sealed cabinet for the mid-bass. Approx .15 to .175 cubic feet if I did my math right.

 

[kappa7krazy]

Good to know. I think I have all the info I need. Now I need to start some drawings and get a cut sheet set up and then the fun begins. Thanks again, Brian.