AE34 receiver volume

[artdecobuchwald]

Hello, friends.
I'm in the final stages of restoring 2 AE34 phones.  They both work and can take and place calls, but I notice that in one phone, the receiver is very very loud, and the other is extremely faint!
The phones are wired identically.  I swapped the receiving elements between the two phones, and the issues did not follow the elements.  I can handle a loud receiver, I guess, but the faintness of the other one is near unusable.  Anyone have any idea what to try?  What is it exactly that has a direct influence on the volume at the ear?  Thanks!

[LarryInMichigan]

The strength of the magnet and the condition and position of the diaphragm in the receiver will make a large difference in the volume and sound quality from the receiver.  Try swapping diaphragms between the two receivers and see if the problem follows the diaphragm.

Larry

[kleenax]

Sometimes, the volume level can be greatly enhanced or diminished just by how tightly you screw on the receiver cap. There also should be a very thin spacer in there, almost like onion-skin paper thickness to insulate the diaphragm from the cap itself.

[artdecobuchwald]

You're absolutely right, Larry!  Thanks for the quick follow-up.
I switched the diaphragms and the issues followed them.  The louder one seems to have been painted at one time, but the fainter one looks original and has some of its textured finish worn away near the center on both sides.  Flipping this diaphragm doesn't help.
Is this where I pony up and buy a new diaphragm or give it a paint job?  Or do you have other suggestions?

Kleenax, I did not find any paper in either handset.  I tried varying the tightness of the cap and it did not seem to make any difference either but thanks for the suggestion.

Adam

[LarryInMichigan]

You can try cleaning and flattening the diaphragm and try flipping it over.  The diaphragm needs to be the proper distance from the magnet and also to be able to vibrate freely.  Any coatings on it or bends will likely affect the sound.  Finding a replacement diaphragm should not be terribly difficult.  Steve Hilsz may have some.

Larry

[artdecobuchwald]

I'll try a new diaphragm and report back on my results.  Thanks!

[countryman]

A worn or scratched center usually indicates that the diaphragm has rubbed against the magnet. That can happen when it is bent. Funny that you get the same result when you flip it. Possibly it is an inferior replacement?
Lacking a reliable domestic source for spare diaphragms, I have cut my own ones out of jar lids. A certain brand of pickled gherkins supplies totally flat telephone diaphragms with the product ;-)
I had good results with them.

[tubaman]

I have fixed this issue in the past by cutting a ring of thin paper and placing it under the diaphragm to lift it off the magnet a fraction. As said, the spacing between the diaphragm and magnet is quite critical. 

[LarryInMichigan]

A worn or scratched center usually indicates that the diaphragm has rubbed against the magnet. That can happen when it is bent. Funny that you get the same result when you flip it. Possibly it is an inferior replacement?
Lacking a reliable domestic source for spare diaphragms, I have cut my own ones out of jar lids. A certain brand of pickled gherkins supplies totally flat telephone diaphragms with the product ;-)
I had good results with them.

That is a good solution when you are in a pickle

Larry

[TelePlay]

Brand new reproductions are readily available on eBay from several sellers. Make sure the diameter of the one you buy matches yours.

Use the eBay search function with the words "telephone diaphragm" to see what's out there.

Here is one of the several listings

https://www.ebay.com/itm/Antique-telephone-candlestick-wood-wall-telephone-reciever-diaphragm-NEW-/112555416967

[artdecobuchwald]

Thanks everyone.  Great forum.  Lots of knowledge.
Oldphoneshop.com and oldphoneworks.com are reliable sources of this kind of stuff as well.  Often they will list on eBay.
I'll try the paper trick first though.  So glad it wasn't something more difficult to remedy.
New to this, I've restored 7 phones since the pandemic started.  Got my hands on these 2 AE34's to add to my "art deco" collection.  They are cool, but no handle like the AE40!  Boat anchors!

[artdecobuchwald]

Following up... I tried the paper trick.  Just a small square of post-it-note under the diaphragm and I have full volume.  Nice.