Altec 604 C diaphragm differences - Help

[bowtie427ss]

Is there a number printed in the other side?

Probably a silver inked "L1" next to the terminal connected to the outermost winding of the voice coil. I wouldn't expect to see anything on the topside unless it was a later pascalite, those had "909" and the maestro inked right on the aluminum dome, i'm betting you've seen them before.

Some part numbers were stamped on the inside circumference of the paper voice coil former

http://i107.photobucket.com/albums/m...sympasfrnt.jpg

- - - Updated - - -

Probably explains why was mine missing after it went to GPA.

Sorry to hear of this. I feel fortunate that i was advised long ago to NOT send working diaphragms or salvageable cones when having anything rebuilt as you will not see them again.

It is also a good idea to tape a note to each component specifying the exact work you want done to it. There's just no substitute for good communication.

[alancohen]

Probably a silver inked "L1" next to the terminal connected to the outermost winding of the voice coil. I wouldn't expect to see anything on the topside unless it was a later pascalite, those had "909" and the maestro inked right on the aluminum dome, i'm betting you've seen them before.

So is there any way to discern which diaphram it is? Not that I care all that much, but since we were on the subject...

[bowtie427ss]

Process of elimination. Once you examine the knowns, impedance, material, terminal type, the possibilities become pretty limited.

I often wonder what changes in the alloy, it's hardness, and it's thickness may have taken place over the years. I'm talking about un-documented changes, and even changes that Altec might not have been aware of until well after the fact. Since Altec never owned an aluminum smelting/processing plant(that i'm aware of), they would have been at the mercy of their supplier where contents and consistency of the diaphragm material was concerned.

Hindsight being 20/20, i wish i'd had the inclination to measure the thickness of all of the vintage diaphragms that have passed through my hands. Sadly, i have divested myself of nearly all Altec product manufactured before the mid 1970's and have only modern Altecs remaining.

[Altec Best]

Although this is quite possible, they are both 1957 production dates and they have been together since new which means they were exposed to the same atmosphere, storage, usage etc.. I would hope that even if a little weak that they are equally weak.. If they came from two different sources I would be more inclined to go along with this theory.

If I sent a speaker out with a perfectly fine diaphragm I think I would get the old part back!! especially given the rarity and price of an original fram!

Even speakers just manufactured in sequential order will have slight variations especially with Alnico... No 2 Alnico magnets will hold the same charge,they will all have slight variations.IMHO.. Just putting power through them will weaken a motor especially after 50 years and if the volume is quite high it will weaken them even quicker..

I can assure you they'll never see my business again, The only reason I sent it was in case they needed to be rebuilt so they would both sound the same. Over 500 bucks in shipping, took at least 4 calls to them to get them on their way back home. They were done the first time I called, three weeks later I was still calling. and in the end I see the phram replaced in the one I told them had nothing wrong with it. just my .02

That is a shame since they are the only place to get original Altec parts.I have posted this several times on this board before..If you send in your drivers to GPA for a rebuild ? No care will be given to the old diaphragms.I posted this about 802-8G's and the lite diaphragm 23744.. Bill doesn't keep them he throws them out..he manufactures new ones..

All this phram talk got me wondering about what I have in mine. I have 604Ds which are similar to late model Cs. I popped the cap off the back, but didn't have time this AM to go further.

These are my phrams:



Is there a number printed in the other side? Can I remove it safely?

Yes on the inside lip underneath there should be a 5 digit number. This is the model #

Look here Alan this is a 23744 diaphragm.


HPIM2345 by Altec Best, on Flickr

Sorry to hear of this. I feel fortunate that i was advised long ago to NOT send working diaphragms or salvageable cones when having anything rebuilt as you will not see them again.

It is also a good idea to tape a note to each component specifying the exact work you want done to it. There's just no substitute for good communication.

Exactly ! I posted this awhile back myself.. If you want to keep your old diaphragms it's best to take them out first before sending them anywhere.. Bill himself told me several times to put a note in the package on what you want done..He has so much work if there is no note he will just rebuild the whole driver,woofer,etc...

You post what you want done.Record all pertinent information and write it on the note.Copy one for yourself..I used Wordpad and printed 2 copies one for me and one for Bill and never had a problem.. The only problem I had with GPA is it took 2 months to receive a pair of 416-8B's one time that he had to recone due to failed spiders from storing face down for many years.

Always record serial #'s too..

[alancohen]

Look here Alan this is a 23744 diaphragm.


HPIM2345 by Altec Best, on Flickr

Ah-ha! I'll look when I get home. I'm OK removing a few screws to find out, just not dislodging things that need special tooling to reinstall. I'd like to know, but not that much!

[cradeldorf]

Sorry to hear of this. I feel fortunate that i was advised long ago to NOT send working diaphragms or salvageable cones when having anything rebuilt as you will not see them again.

It is also a good idea to tape a note to each component specifying the exact work you want done to it. There's just no substitute for good communication.

I bear some of the responsibility as I did not send info in both boxes as to exactly what I wanted done nor did I include pre paid return labels. So not entirely bills fault.