Help With Altec Compression Driver ID

macaltec

Metal Master
So I have a couple of Altec compression drivers. One has it label on the cover 808-8A the other has no identifying marks. Is there anyway of knowing exactly what I have?20190317_125221.jpg 20190317_125113.jpg 20190317_125238.jpg
 
The diaphragm will identify the driver.

If it has an aluminum tangential surround diaphragm, it's an 802.

If it has a reddish amber "kapton" surround, it's an 808.

Carefully, remove the covers and take a peeksee.
 
Ive had these things for years and am experiencing a renewed interest. I believe the diaphragms have already been removed, but I am going to check anyway. My main concern was with replacement diaphragms, would there be any difference in physical fit or sound if the bodies are not identical?
 
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808-8A is on the left. I dont think I have ever been into this pair. Will the same "new" diaphragm fit both?
 
I want to say that at some point I thought the one might be an 807. Cant remember why or when this thought came about.
 
Negative on the 807, that uses the shorter body and smaller magnet slug of the 806. Front to back, the 807 is about 3/8 of an inch shorter than what you have.

Yours are definitely the larger 802/808 body.

Those are genuine symbiotik diaphragms. The one on the right with the push on terminals is a replacement, but it is genuine/correct.

They won't give you the last word in HF extension, but they can make a substantial midrange driver, just add a tweeter. Or, you can put GPA aluminum tangential surround diaphragms in them to gain significant HF extension.

Check the working condition of those diaphragms.
 
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One is dead and the one that is unmarked is good but looks to have been crudely repaired. Certainly will be getting new diaphragms for them as I have recently acquired a second set of 511 horns (that I had to fix a large section of one). I have a set of 828 (and/or the other one used for A7s) cabinets waiting in the wings. I have either 416-8A or 421-8H or is 8LF, havent looked at them in years.
 
Don't discount those 421's, especially in a plain old reflex box. In the 828's, for hifi, the 421's aluminum domes would need to be damped, or replaced with a paper version. If you seal off the 421's rear vent, and install vented Altec dustcaps, they will look "right".

GPA diaphragms have taken a good hike in price, Radian 1228's are a bit less costly, more robust than the all aluminum 802 diaphragm, built similarly to the Altec Symbiotik, and sound very good.
 
Good to hear (no pun intended) about the Radians, I have a set on my other A7s and was considering them for this set. Interesting info about the 421s and the dustcap.
 
I would very quietly encourage you to compare the more relevant T/S parameters of the 421-8LF to those of a 515B. Look at Vas, Qts, and Fs. http://alteclansingunofficial.nlenet.net/Thiele-Small.html

If you damp, or altogether remove the aluminum domes, the sonic signature is not at all far off from the 515, and that's not a bad thing.

But, if we speak too loudly of this it will drive up the value of 421LF's. I had a wonderfully clean pair, and regrettably traded them off. I wish i had them today.
 
Mums the word.....

This will allow me to use the 416s and my 811s for a Model 19 clone of sorts. So many projects......
 
They are 808-8A which use the diaphragm with the synthetic surround, It limits the response above 13 KHz but handle more power below 1000 hz, especially if the rear percussion cap is included to prevent over excursion of the diaphragm down to and below 500 HZ. Don Davis said never operate small Altec drivers below 750 HZ. They will handle twice their rated power if you you follow that rule. Who is Don Davis, he worked with Altec for many years and spear headed the development of 1/3 octave room equalization among other things in the late 60's and early 70's.
 
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