Repace Diaphragms myself or send them to GPA?......

[bowtie427ss]

One thing that 'bothers' me a little, is that the replacement diaphragms that GPA uses for the 288-16K, requires a 'conversion kit'.

Not to worry.

If i'm not mistaken, the "conversion kit" is simply a new pair of lead wires that connect the rear cover mounted terminals to the terminals on the diaphragm mounting hub.

"Conversion" is necessary as new style diaphragms use 1/4" push on type connectors, whereas older diaphragms used a screw terminal. It's simply a matter of different connectors on the diaphragm end of those wires.

Depending on the exact vintage of your drivers, they may already use the new style setup.

At any rate, GPA will supply you with everything you need including instructions, except for a good philips head screwdriver(non magnetic a big +) and steady hand.

[sba2]

...Large format Altec... For proper installation the pins need to be loosened, and the diaphragm is centered using the shim that will be supplied with it. Locating pins/dowels are then tightened so that the diaphragm can be re-installed in the exact same position after the shim is removed.

I didn't know that. It seems that this might be a better design for critical/hifi use than the simple "drop on" design of the small format drivers. Using RTA, and being able to make adjustments, one could get the phragm in the optimal position.

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Those phragms from Arizona, at least the small format ones, look exactly like the aftermarket junk that I got from Orange County

[Panomaniac]

I've read the Altec sheet about the shims and positioning of the large format diaphragms. It does not look too tricky.
But does GPA supply the shims if you buy the frams without installation?

[bowtie427ss]

It's not the best quality scan, but this sheet shows the spider shim and the adjustable guide pins. There might be better resources at the GPA website.

http://www.altecpro.com/pdfs/vintage...nstruction.pdf

[bowtie427ss]

Here's the GPA sheet, since they show it, i would assume the shim is included just as it was with the Altec branded phragms.

http://www.greatplainsaudio.com/LgDrvrDiaRepl.pdf

[Panomaniac]

Thanks Bowtie, that's the sheet I read.

[Altec Best]

A 288-16K will have a ceramic magnet. It won't need to be recharged.

Was talking in general.If it needs a kit then it is old enough to possibly be alnico Right but a 16k is ferrite your right.I've seen some ferrites that lost magnetism I talked to Bill about this they can lose magnetism in the right conditions,in fact I had a pair that were new over a 25 year period I feel that they lost some magnetism even though they are Ferrite/ceramic all magnets lose magnetism and the longer the period plus right conditions the greater the loss.

[DSauro]

Changing the diaphragms can be, and should be, a pretty simple procedure; but that wasn?t the case with my first install on some 807s. The problem was that I bought Orange County Speaker?s aftermarket diaphragms, whose mounting holes and registration pin holes were off just enough that I had to bring out the drill and enlarge the holes. It was a PITA... and I never got them seated and working properly. I ended up junking the diaphragms and shelving the 807s.

If you do-it-yourself using actual Altec/GPA diaphragms you really should have no problem. If needed, there's even a GPA instruction manual (somewhere) for doing it. My 802-8gs, on the other hand, are at GPA right now getting new diaphragms, because I needed the alnicos re-magnetized, too. GPA?s prices, by the way, are very reasonable.

The replacement diaphragms I got from Orange County Speaker were from Great Plains Audio.

[bfish]

... I feel that they lost some magnetism even though they are Ferrite/ceramic all magnets lose magnetism and the longer the period plus right conditions the greater the loss.

...Maybe on this planet...;

[sba2]

The replacement diaphragms I got from Orange County Speaker were from Great Plains Audio.

Good point! I learned later that Orange County Speaker carries GPA, Radian, and aftermarket diaphragms. Without doing much research, I had bought the aftermarket ones that OC lists on ebay.

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I didn't ask Bill if there was a cheaper DIY price; but, at $95 per small-format phragm (installed & re-magnetized) his price beats all others.