902 differences

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I have a vanilla looking 8-ohm Altec 902 compression driver. There's no metal cover on the back and no rubber surround on the magnet. It has a black plastic cover over the diaphragm with 2 spade lug terminals. Numbers on the magnet are 8644 and QC71. The numbers on the integral gasket read 84635.

Can anyone identify which model of 902 this is?

Looks like there's a permanent gasket which helps secure the screen. Does this also serve as the horn coupling gasket, or do you need to use another gasket with these when mounting to a horn?

Thanks!

<img src=http://myweb.cableone.net/jpg/Altec_902d.jpg><img src=http://myweb.cableone.net/jpg/Altec_902c.jpg>

[Old Guy]

This is one from inside a cabinet- if it came from a steo unit it may be a 902.

I would check which diaphragm- it could be one of the symbiotiks, which would mean it's not a 902 it's a 908. My knowledge of these is very marginal.

Lots of drivers came no magnet cover. I think the main difference is diaphragm, whether it's aluminum, symbiotik or Pascalite.

[jpg]

Thx for the reply OG, I bought this at auction a couple months ago; the seller said that it came out of a 9844-8B cabinet but wasn't exactly sure which model it was. I looked at the 9844-8b file at altecpro.com, it mentions "902 Type HF Compression Driver" but not which model, -8A, -8B or -8T.

I pulled the diaphragm, it's a 35480 lightweight aluminum. Would that make it a 902-8A?

Thanks, Jim

[Old Guy]

902 type means derived from a 902. There were 418 and 421 "type" speakers that were not regular 421's or 418's.

Probably close enough to an A or B to match up. If the diaphragms are the same the drivers will sound about the same.

[jpg]

Works for me, thanks!

[jnorv]

jpg, are you interested in the rest of the parts for that 902? I have a dead 902 (loose magnet), can't be repaired. With out the mag it would be cheap to ship.

Jim N

[Russellc]

The 902 8A would not normally have a loading cap.
If you have the aluminum diaphragm, its probably a 902 8B. But after all these years, who knows?

russellc

[bfish]

I asked Bill once about getting some new tires and covers for some of those (they also came in M500s). He asked "Why?", and after thinking it over, I had to agree.

[Old Guy]

Originally posted by Russellc:
The 902 8A would not normally have a loading cap.
If you have the aluminum diaphragm, its probably a 902 8B. But after all these years, who knows?

russellc

<font size="2" face="Verdana, Helvetica, sans-serif">True. And of course the cap can be removed and a regular cover used.

I think that was the major difference.

[TnTn]

I have a similar pair, but with burnt voicecoil. On close inspection, I noticed that the voicecoil gap is a bit wider than a regular 902's (the one that's labeled ith 902's part number) gap. Also, the phaseplugs on mine are greyish tangerine type plug, not orange/tangerine. I tried out with some aluminum diaphragms and they sound fine. I wonder if, with the wider gap, diaphragm needs to be aligned to prevent voicecoil rubs.