Real kappa 8.1 polydome diaphragm?

[Fleime]

Well, despite some comments I have made in other threads I have taken a leap of faith and got myself a Kappa, version 8.1i. I decided on buying it based party on the overall condition (e.g. it appears to have the original surrounds) and sound, but mainly on the appearance of the polydome diaphragmas. I have been hesitant to go on the polydome adventure because of the replacement issues (despite recent developments by Bobbyd38), but I have wanted to have at least tasted them (and the Kappa line in general). I think it is clear they destroyed my (poorly maintained) Reference 50's, the sound is amazing. I now have a much better understanding of the concept soundstage. And size. And complaints of the better half. Although she was actually amazed about the (voice) clarity.

Anyway, although the polydome diaphragmas look original, I wanted to check it with you guys. I think they have been cleaned explaining the relative transparency, supported by residual traces in the 'surround'. However, there is a slight fear that they are fake duplicates (silicone?), hence the question. I do not know if it is relevant, but around the 'peak' of the bulge an outline of a ring is visible, like from a mold (photo 98 when zoomed in).

Thanks.

 

[goodolpg]

Did the OEM .1 Kappas suffer the same dome degradation as the original Kappa series?

 

[seifreit]

@Fleime , Look pretty original to me, nice find getting any original polydomes in that condition.

Did the OEM .1 Kappas suffer the same dome degradation as the original Kappa series?

Yes, I picked up a set of 6.1s recently and the polydomes were intact but really fragile. I took the chance on trying to freshen them with the 303 protectant that everyone seems to have success with. Worked well on the first one, second one not so much. Applied protectant and gently started to wipe off excess with a q-tip and a dime size piece just crumbled off. Did a “repair” to it with a piece of tissue paper doped with woofer surround glue. Point is, yes, the later K x.1 and x.2 degrade in the same way as the first series.

 

[goodolpg]

Thanks seifreit, I wasn't sure. I guess I was secretly hoping Infinity had realized there was an issue and had remedied it though the time frame between the original and the .1 series probably wasn't long enough for the degradation to be apparent.

 

[jazzmans]

Did the OEM .1 Kappas suffer the same dome degradation as the original Kappa series?

yes.

iirc, treating with silicone every six months or so, prevents them darkening and cracking.

Unfortunately, no-one figured this out until 20 years after they were manufactured.

 

[Bahamayellow]

Congrats on your 8.1s. My first kappa Speakers and still have are my 8.1s. I tried to power these with a reciever and with a epic fail. I am bi amping these now and love the way they sing. Can listen for 10 hours or longer without fatigue and really fills the room. Post your pics when you can.

 

[swechsler]

When I bought my Kappa 8.1s about, I don't know, maybe 8-10 years ago, the polydomes were also clear. They clouded up over time, however, even though they have spent their entire lives with me in my master bedroom. The material is still pliable. Original woofer surrounds are still good; Infinity used a different type of foam with these. Unfortunately the same can't be said for the woofers in the Kappa 6.1s, which expired many years earlier.

 

[Fleime]

@seifreit Thanks for the reassurance!

@Bahamayellow Thanks. Yes they appear in very good condition, with the exception of some cosmetic damage. Although I have yet to properly install them (e.g. room placement, equalization), they already sound great. Should I post pictures here or in the 'show your infinity's thread'?


A correction: the version is an 8.1i, I do not know if that makes any difference to 8.1 without the i.

The seller (dealer) informed me that the polydomes have been replaced recently by his original. When inquiring further, he believed the entire drivers were replaced, not only the diaphragm's. I have yet to receive an answer whether he can verify this, or perhaps put me in contact with the original seller. It is not that important, seeing as the part numbers on the magnets are correct.

Of more importance to me is whether the diaphragm's have been cleaned and with what product. I am of the opinion that they have been cleaned (or more like wiped down) with the swipe traces still visible on some places. Please inform me if you agree/disagree with this assumption.

If my assumption is correct, I would rather clean them again more thoroughly/carefully myself with a known product in order to maintain them, as touched upon by seifreit and jazzmans.

 

[Ross6860]

Silicone and polyethylene have a completely different feel.

A gentle, really gentle, touch should tell the difference.

I had a pair of Kappa 7.1 S2 and the crossovers were beautiful to behold. I think Infinity used 12-gauge fine-strand wire throughout. Woofers were very heavy and well built.

They also sounded very nice. Plenty of low end, and the mid and tweeter are legendary.

Enjoy!

 

[swechsler]

IIRC, replacement Polydomes were available from Infinity in Europe many years after they stopped selling them in the US. That could be where they came from.