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ALTEC9846-8A
01-17-2008, 10:24 PM
I have a 9846-8a and want to know if terminal 2 is pos and terminal 1 is neg(on the horn). I also have a attenuator(30904) but the info says it should be a 30923. which is the right one? no one seems to know for sure. IF you could help me restore this right your help would be appreciated. do not say unless you know for sure. thanks keith in victoria

Zilch
01-18-2008, 12:52 AM
Remove C2 and/or R3, if you feel you must....


http://audioheritage.org/vbulletin/attachment.php?attachmentid=30460&stc=1&d=1200167829

jimd
01-23-2008, 12:10 PM
The plus terminal of the 802 drivers is #2. In old phone company terms, remember where they came from, when you apply positive voltage to L1, the diapragm moves away from the magnet. In the case of the 802 and other "inside out" type HF drivers, where the builders routed the sound output through the magnetic assembly, the magnet is in front of the diaphragm instead of behind it like conventional drivers. Therefore, to get positive pressure at the exit of the Altec HF driver, one must apply positive voltage to L2, or 2, in this case. In the case of Altec cone drivers marked with 1 and 2, #1 is hot as tha magnet is behind the cone. Confusing, yes, was really nice when they went to Red or + on the hot terminals.

JIM

ALTEC9846-8A
01-23-2008, 07:40 PM
thanks for the info. i have since found the picture on the back of a 30904 attenuator and in that picture they show terminal 2 as pos also thanks keith in victoria

Art J.
01-24-2008, 06:56 AM
"I have a 9846-8a and want to know if terminal 2 is pos and terminal 1 is neg(on the horn). I also have a attenuator(30904) but the info says it should be a 30923. which is the right one? no one seems to know for sure. IF you could help me restore this right your help would be appreciated. do not say unless you know for sure. thanks keith in victoria

Hello Keith
We went through this years ago on the Altec board. Their were many errors between Engineering
and the Marketing department. We have found no errors in the driver reference guide.
http://www.lansingheritage.org/images/altec/reference/1975-drivers/page11.jpg (http://www.lansingheritage.org/images/altec/reference/1975-drivers/page11.jpg)
The 30904 has the Zobel for the 411 woofer and is correct for -8a model.
Here are the un-cut diagrams for the -8a if you want them.

http://webpages.charter.net/artj/Altec3090430923.jpg (http://webpages.charter.net/artj/Altec3090430923.jpg)

http://webpages.charter.net/artj/AltecN-501-8a.jpg (http://webpages.charter.net/artj/AltecN-501-8a.jpg)





:barf:

ALTEC9846-8A
01-26-2008, 01:56 AM
when I took these apart I found I had a 808-8a driver instead of a 802-8D. They both use tha same diaphram( 34726 symbiotik). Does it matter that I have different drivers and what is the difference between the two drivers. If they are the same ,why the different numbers?

Art J.
01-26-2008, 08:14 AM
***************
when I took these apart I found I had a 808-8a driver instead of a 802-8D. They both use tha same diaphram( 34726 symbiotik). Does it matter that I have different drivers and what is the difference between the two drivers. If they are the same ,why the different numbers?
***************
If the 9846 was ordered for large venue applications, it would come with the symbiotic
in order to handle more power at the cost of some top end.
The studio monitor version came with the 802 with the 21597 diaphram for more Hi-Fi.




:barf:

jimd
01-26-2008, 10:40 AM
I was there at the contractors meeting on the day ALTEC released the 9846. From my conversations with the designers I do not believe they ever had an 808 in them. I think someone switiched the drivers somewhere along the way.
If the speakers were installed by an ALTEC contractor, this driver switch was altogether possible as they did this all the time for, as Art J said, higher power useage. In reality, the component driver in the 9846 probably would not have had a model label on it, just a rubber stamping, to me the 808 seems like a switch.
For your use, I would install the 26420 Pascolite alumium alloy diaphragms into your drivers as the 802-808 motors are the same. These diaphragms sound and measure identically to the lower power soft aluminum 34647 and handle three times the power.
I would hang on to the 34726 Symbiotic diaphragms for a while. They are begginning to get scarce as they are no longer made. Currently there is no great resale market for them, but as time goes on that will change as people that still are using their drivers in PA applications and those who want to keep their drivers original will someday want them. Actually, the 34726 is the newer version of the Symbiotic diaphragm with the spade terminals. The 808-8A originally had the 21545 with the screw terminals.
JIM

ALTEC9846-8A
01-26-2008, 01:36 PM
So the 802 and 808 are basiclly the same ,I will not need to replace the hf driver but which type of diaphram do i have? I took it apart. Found an alum diaphram with a black plastic ring.Between the diaphram and ring was a brown see through plastic.Only number i could see was 291746. This was on a metal ring between the outer plastic ring and the magnet.There may be a number under the metal ring but the ring seems to be holding the diaphram in place so I didn"t want to try to pry it off in case I wreck it.Where do they put the diaphram part #?

jimd
01-26-2008, 03:06 PM
You have the classic Symbiotic 808 diaphragm. The translucent brown ring between the dome and the plastic ring is Kapton. If the diaphragm has screw terminals it will be a 21545 original diaphragm, if it has push-on spade terminals, it will be a 24726, correct for a 908, replacement for an 808. The two diaphragms are electically and sonically identical. The Symbiotic handled 30 watts, the standard aluminum tangential compliance diaphragm of the time (21597), 10 watts. Unlike metal diaphragm surrounds, the Kapton does not fatigue, but is heavier and will not respond as well in either the extreme upper frequencies or transiently as the aluminum diaphragms. It was a superior product for PA and high level purposes until the newer Pascolite 30 watt diaphragms came into being which sound just like the older aluminum ones but are much more rugged. Ultimately, the Kapton surround will probably stand more cycles of use before breaking under extreme use, than the Pascolite, but that could be up to debate. I don't think you are using your speakers in that kind of venue. The Altec MI speakers produced punishing high sound pressure levels and still sounded good. Something we don't see today. For your case, just change the diaphragms and you are good to go. I would use the 26420 Pascolite models, we use them in our 704 and cannot hear or measure the difference between them and the lower power units, despite what those who claim to be able to hear grass grow say. The number you see is probably a priduction number, sometimes they didn't put the part # on the diaphragm. JIM

ALTEC9846-8A
01-27-2008, 01:05 PM
thanks for the info. I have the screw terminals so i will have to replace them with 26420. I thinking great plain:)s audio.It seems to be the place for altec parts.I know there are cheaper places but am not sure of the quality.After spending so much on this project,I should't go cheap now.