802 Diaphragm Inquiry

[DLK]

Hi,

I have acquired two late-model 802 drivers that I want to use on 511A horns. While these look the same on the outside, they are somewhat different internally.

802-8G:

-no bakelite cover behind diaphragm
-felt pad attached to inside of back cover
-old style screw connectors
-numbers - 28744 18586 8 391834
-"shorter" voice coil length

802-8T:
-bakelite cover behind diaphragm
-no felt pad
-new style push-terminals
-numbers - 34647 91-19
-"longer" voice coil length

I'd be interested in learning what sort of difference in sound I might expect between these, particularly the effects of the "short" coil.

TIA-
Dan

[Russellc]

I think you will find that the voicecoils are the same length. The bakelite cover you speak of is a loading cap. while the voice coil-loading cap assembly looks like a single piece, it is actually two. the loading cap can be pried away from the diaphram, after unscrewing the three screws which hold them both in of course. I think you will then see they are the same size. However, with that much removed, you will find the screws now bottom out before being tight enough to even contact the voice coil, so shorter screws are required. The diaphram with the loading cap is also likely a "symbiotic" diaphram, while the other 802 w/o the bakelite loading cap has the standard aluminum diaphram. Also, the earlier diaphrams have the spade type lugs. Conversion parts, short screws, and the felt pads are available from great plaines.The loading caps allowed the diaphrams to be driven harder in PA type use as did the symbiotic diaprhams, at some cost in high end transient response. Also, I believe some of the later 802 8G had the tangarine phase plug, while regular 802s had the standard slotted phase plug. With the loading caps, the felts are not used. I feel the sound better with the loading caps removed and the felts installed. Hope this helps

Russellc

Russellc

[martyh45]

The 802-8T is a G with the loading cap and no felt. Both have tangerine phase plugs. You will want to use the original 34647 in both with no loading caps (add felt to the 8T).

[Jim D]

The 802-8G as well as the 604-8G and 616-8A originally did have the 23744 diaphragm with the shorter voice coil. This was ALTEC's attempt to lighten the moving mass and thereby enhance extended HF. We replaced a lot of the 23744s. I always thought it used a thinner aluminum because all the failures had shattered diaphragms with the domes coming out in flakes. I do not think I ever saw one with a burned voice coil. JIM

[yup]

Dan,
I have a pair of 802-8T's that had a pair of the 23744 diaphrams...

I have heard two different explanations as to why that diaphram had better HF response. The first was that the aluminum was thinner and the second was that the voice coil was lighter, maybe it's both.

Unfortunately, one of mine was destroyed by the phase plug coming loose, leaving me with only one.

Since we both have one, e-mail me and we can figure out some sort of trade.

Thanks,
Jeff