Altec diaphragms for 802-8d drivers

[NickH]

Hello,

I bought 2 802's from a forum member a while ago. Only one had a diaphragm with a surround that looks like kapton. Are these symbiotic diaphragms?

I purchased 2 new diaphragms from GPA when I got the drivers. They had tangential surrounds. I had an accident the another day with a screw driver and put a hole in one. I was so mad. My wife though I had hurt myself or something because I was yelling profanities.

I put the one diaphragm back in with the plastic surround. I was wondering if there's any preferences by people for one or the other?


this all happened because I removed the loading cap from them. I read they sound better that why, which they didn't. It all happened putting the cap back on.


Thanks,
Nick

[Horn Fanatic]

Hello,

I bought 2 802's from a forum member a while ago. Only one had a diaphragm with a surround that looks like kapton. Are these symbiotic diaphragms?

I purchased 2 new diaphragms from GPA when I got the drivers. They had tangential surrounds. I had an accident the another day with a screw driver and put a hole in one. I was so mad. My wife though I had hurt myself or something because I was yelling profanities.

I put the one diaphragm back in with the plastic surround. I was wondering if there's any preferences by people for one or the other?


this all happened because I removed the loading cap from them. I read they sound better that why, which they didn't. It all happened putting the cap back on.

Thanks,
Nick

Greetings-

The symbiotic diaphragm you have is the 802-8D. The 802-8D can handle a bit more power, but lacks the higher frequencies of the aluminum and Pascalite diaphragms due to the damping property of the Kapton. The -8D diaphragms were a big hit in the seventies with bands using A7's for their P.A. system. Yuk! I can remember a few service calls at 11:PM or so by friends from what ever bar they were playing at, complaining about their horns not working. These people would put so much power through the horns it would pulverize the diaphragms into crumbling flakes of aluminum. I replaced their diaphragms with the -8D so I could get some sleep! If I had a nickel for every abused diaphragm I replaced I could by a nice steak dinner for two.

I think a big part of the problem were the ALTEC crossovers. In my own systems I crossed 1" drivers over around 1.2K in live situations just to protect the diaphragm. Using a steeper slope is another safety precaution. Personally, I would use the aluminum 902 diaphragm for HiFi, not the 908 Pascalite alloy. But that's just me.

As for the loading cap. What the cap does is introduce a reduced acoustical compliance. To do so enables a bit more power to be applied to the driver. As I have never conducted an A/B test I'm unsure if it would make a difference at living room listening levels whether is was on or off, but for a P.A. I would recommend using it.

And about your dented diaphragm. If it's not severe I wouldn't worry about it. I'd be hard pressed to think your wife and friends would tell one from the other and poke fun at you. :-P However, audiophiles can be ruthless!

H.F.