‘68 Greenback purchase

[the2x12ammunition]

What are some things to look for on the speaker cone that indicates bad condition? Never bought a new greenback before but this is a pulsonic G12M I’m potentially paying a lot of money for, so I want to be careful. Any input appreciated, thanks!

 

[neikeel]

I guess a lot of people are sitting back for someone else to answer.
The clearest answer is how does it sound?
Does it have the original pulsonic cone stamped on back with xx xx 102 number for 75Hz or 014 for 55Hz.
No rips, no tears, buzzes, scratches through the correct range. Depending if early or late 68 the frame code (T1221 or T1511) might be on the pale card front gasket or on the edge of the frame. Could be paper voice coil 20w vs later 25w type. Solder mount tab should be black etc.
Are you going to run it in an iso cab or 1x12 ?
What amp?
Attenuator or no attenuator
Pics might help.

 

[giam23]

Agree with what Neil said.

I would check the spider is evenly well glued down and doesnt look like it has been re-glued. Test the voice coil for rub by VERY CAREFULLY pushing the cone down and also pulling it up from the underside. I generally do this with all my fingers to push down and a cupped hand to pull up because if you concentrate that force to one finger you will push your finger straight through the cone. Cone stamps are very important

Measure the impedance with a multimeter and make sure its in spec. I would also highly recommend studying some images of these speakers because if you have seen a few you can generally spot irregularities pretty quick.

But as Neil said, if you can, play through it and see how it sounds, thats all that really matter at the end of the day

The best way would be to get some photos and post them here if possible so we can give you our verdict

 

[Fernieite]

Brian's website has excellent articles about vintage greenbacks! It's quite possibly THE best resource on the subject.

How To Test A Vintage Celestion Greenback Speaker - Bygone Tones

How to test a speaker for: voice coil rub, blown speaker, torn cone, and other common problems. Using an audio generator for 'sweep testing'.

www.bygonetones.com

 

[StingRay85]

The cone should be clean, the ribs should still be well defined. Pulsonic cones are very smooth and should not be stiff. No fixes, punctures, soft spots, especially around the edges of the cone. No mold. No discoloration (when they look brownish, they've seen too much daylight and probably left on a shelf somewhere for years or decades). No dirt or mold on the dust cap, it should still be open. Spider should still be firmly attached. No signs of degradation of the glue that was used to fix the spider to the frame. The color of the glue should be yellowish, and not red/brown. No voice coild rub. The position of the cone is also important, it should not be too much pulled inside the coil gap either... Only if this checks out, you could consider paying top dollar for it. But I agree with the above too, make sure it sounds good to your ears

 

[BygoneTones]

Whenever I get hold of a speaker, the very first thing I always do is check the spider support is fully glued down, because it's the most common fault with them in my experience. Secondly, I'll check for coil rub by pressing lightly all around the front outer edge of the cone, not directly down on the center like most people do, and by pressing from underneath the cone. Then just eyeball for other issues, make sure the outer gasket isn't lifting off from people yankin speakers out of cabs with brute force, check the dusctap isn't lifting off, no tears or things stuck under the cone - metal objects like staples and small screws can get magnetised under there.

That will weed out 9/10 faulty speakers in my experience.

Then I do a low frequency sweep test with an audio generator.

Lastly, always play through the speaker. This is the most important test. And play through it loudly so that the cone is visibly moving a significant amount. Just playing some music quietly into the speaker with the cone only vibrating a miscroscopic amount won't usually tell you if the speaker has any issues. Connect amp and guitar and dime it enough so that the cone moves. Any buzzing or rattling is bad, obviously.

As for condition of the cone, ideally it should be grey/blue in colour, rather than brown, and firm to the touch.