Altec 807 measurements

[Earl K]

I was about to go crazy...It was a relief to discover that there are widespread problems with diaphragm alignment--

http://audioheritage.org/vbulletin/s...802#post249075

That is my original post that you are referencing and which discusses aftermarket replacement frams for Altec drivers.

I would not characterize the conclusions in the post as widespread alignment issues with Altec diaphragms. Rather, I would say that the aftermarket frams and old OEM tested in this post SUKed.

Radian diaphrams are aluminum with a mylar surround. I've used them in Altec and JBL bodies and they sounded good to me. But now that they're almost as expensive as GPAs one might as well use GPAs in Altecs.

- I won't argue the point with Tom about Radian diaphragms / but this is as good as I could get the FR to "look" with the same Radian diaphragm fitted into 2 different Altec drivers . I'm sure it sounds better than the picture.




- I was eventually able to fitup my old Altec 35480 diaphragms into 2 different 802D bodies // with the original phenolic-plastic loading caps reinstalled ( but no backcaps ).
- This is the performance those old Altec diaphragms were able to offer ( after a pad, a single pole HP and a RC contour circuit were all implemented ;



- That trace above shows remarkably linear midrange from a diaphragm that I had thought was "pooched" ( within a different thread ) .

- Below is the "worst" of the two 35480 diaphragms that I own / showing the effects ( before & after ) of a High-"Q" notch filter being applied (at around 7K) .



- So at this time, I can't agree with Robert that my old Altec OEM diaphragms "SUK" / but I will state that " the Radians have yet to prove their worth to me".

<> cheers

ps 1 ; I guess I should update that other thread sometime .
ps 2 ; The statement made within that other thread still holds true / installing diaphragms is not just "plug & play"
- ( even with test gear, getting a good fit-up can be very time consuming & it doesn't always occur ) .