clay wrapped voice coil .... whassup wit that? see pix

binarywhisper · « **on:** 3 May 2004, 01:14 pm »

I removed the dust cap on these woofers in prep of redoing the surrounds and found this.

putty in place

putty removed

So whats up with that? These came out of a pair of Infinity Qjr's although I beleive that they are not actually original to the Infinities. The cone is very heavy paper with a strange grey coating with reflective specks painted on it. I beleive I saw woofers like these in a pair of 70's Sansui speakers.

Regardless, what do you beleive that this accomplished? Any suggestions?

_scotty_ · « **Reply #1 on:** 3 May 2004, 05:53 pm »

It was there to increase the cone mass and lower the drivers fs. The added mass also lowered the drivers efficiency. You might check this website for more info http://www.bobbyshred.com/infinity/Qjr.html
The picture on this website of the Infinity Quantum Jr. shows a blackcolored woofer so what is in there now might not be original.

Here is another website on Infinity loudspeakers
http://oellerer.net/infinity_classics/
Goodluck on your repair,Scotty

binarywhisper · « **Reply #2 on:** 4 May 2004, 02:54 am »

so you don't think that it has any significant effect on the tone of the speakers? Was this a common method of tuning a driver?

_scotty_ · « **Reply #3 on:** 4 May 2004, 03:44 am »

It absolutely affects the sound the woofer produces, if you like the way the speaker sounded before you undertook the repair job you will need to put the clay back in when you are finished to restore the sound you are used to. It depended on the manufacturer, and if they were trying to use one woofer in as many models as possible. The resilient mass located near the voice coil would tend to induce a mechanical rolloff of the woofers midrange output and maybe part of the crossover design in this speaker.