Kappa 8A crossover issue

[Anomalia]

Hi,

I have a strange problem with Kappa 8A. When I listen at low volume, the Polygraph remains silent for a long time, it may take an hour before the sound starts to come out. The bigger the volume, the faster the element starts to work.

If I increase the volume considerably, the sound can be heard almost immediately (a small bang is heard).

If I listen at a low volume after this, the sound starts to fade from Polygraph and disappears after a while if the volume is not turned up.

I cleaned the pots but it had no effect on the problem. The elements are serviced.

In addition, both speakers have a really big damping in the +-4khz range and the phase sounds somehow strange. Sometimes they sound muffled, but sometimes they sounds amazing good and perfect.
Can you tell if the problem is faulty capacitors?

Has anyone changed the capacitors to the original ones, do you have a list of the components?

 

[seifreit]

The first thing i would check is if the pots are actually clean/working properly. You'll need to unsolder one of the leads and test them with an ohm meter to see if there are any dead spots or inconsistency in the sweep. The second thing I would check is the self-resetting circuit breaker. Although, this would not cause a gradual fading. It would simply cut on and off.

A recap is a good idea regardless of any other issues given the age of the speakers. I would open them up and order parts based on what is installed in your speakers and not trust the accuracy of the Tech Sheet or what someone else may have used for their recap. Infinity was notorious for making running changes to the crossovers and many of those changes are not documented, at least not onthe Tech Sheets.

 

[Anomalia]

Thanks for the tip. I measure with the pots removed.

Also thanks for the information that there can be differences in crossovers, I'll try to find out what's installed and install new parts accordingly.

 

[Anomalia]

Now I had time to replace the components. What material is the crossover back plate? Is asbestos used in these?

 

[swechsler]

No asbestos. Newer circuit boards are usually fiberglass. Older boards (typically 1970s and earlier) were phenolic resin.