Difference Between 806 and 802 Drivers

[Earl K]

I should probably note the 806 was initially called an 804, then changed for some reason.

I suspect to avoid confusion with multicell numbers

Steve Schell addressed some of this very question in this thread over at LHF .

Tom, I have it on good authority that the Altec 804A and 806A drivers are not identical. Although they look the same externally, the 804A has a considerably smaller alnico magnet than the 806A which was its successor. The 804A was introduced during a period when management was cheapening the Altec line into oblivion; the 605A replacing the 604D was another example of their insanity. Apparently the 804A's magnet was weak enough to move the mass corner downward and begin losing the top end, prompting the introduction of the 806A after many complaints to get the h.f. response back.

Steve I'm forced to wonder about your source and his credibility. Jim Dickinson states the 804 was made from 1961 to 1964 and then rebranded as the 806 in 1964. Dickinson seems to know his Altecs.

Comparing 804 specs and 807 specs (1968 807 specs, and all seem to agree the 807 is an 806 with symbiotic) show the 804 and 807 having the same magnet weight, magnet strength and overall unit weight. This tends to confirm that the 804 and 806 are the same driver.

Perhaps your pal is confusing the 804-806 thing with the 802-806 thing.

Tom, I checked with my friend Robert. He says that despite the published specs there are indeed several differences between the 804A and 806A examples he has had apart. He says the 804A magnet has a smaller outer diameter and the phasing plug has smaller slits, giving the driver a higher compression ratio than the 806A. He also said that the diaphragm in the 804A may have a shorter voice coil than the 806A, though he is not certain about this.

I remember taking apart a junky pair of 605A Duplex drivers years ago, and was surprised to find that the h.f. driver phasing plugs had smaller slits than the 806As and 802Ds I had at the time. Robert says that the 804A and 605A share this higher compression ratio phasing plug.

Robert is in the middle of moving, but if he can find these parts he will bring them to me to photograph. Stay tuned.

Robert brought me the magnets from Altec 802D, 806A and 804A drivers. As I hope can be seen in my crummy pictures, the 802D and 806A magnets have the same inner and outer diameters but are different heights as the 802D has a longer body. The 806A magnet has the same height and inner diameter as the 804A magnet, but the larger outer diameter that it shares in common with the 802D magnet. I don't know why these relationships aren't reflected in the Altec literature of the time, but suspect that the corporate cost cutting and subsequent eating crow may have played a part.

This seems pretty definative to my eyes .

Yet to be addressed ( with pics & measurements ) is Steves'/Roberts mention of the different phase plug found in the 804/605 duplex .

Also ( some conjecture ), the reworking of the 804 into the 806 may have triggered the development and introduction of the 23744 ( lite ) diaphragm ( to help restore the HF of the 806 back to the level of the previous generations, 802 ). Just a theory, mind-you

<> EarlK