Large Advents (1974) woofer pops with deep bass.

@vcheney 

Whatever elements that define the level of attachment you have to the Advents are valid ones, in my view.  Only you can place a value on them.

You probably have an "unhealthy" woofer there.  I like @dekay process for troubleshooting the woofer.  It's a no cost, zero risk method.  So, I think it's a good place to start.  You can also try gently pushing in on the woofer while in the cabinet and letting go.  The woofer should take a moment, or two, to move back to the starting position.  If not, there's a breach somewhere.

Repairing the woofers is a virtual rebuild where all things that move are replaced.  You'll essentially have a new woofer when you are done.  Magnet strenght may weaken over time.  I believe this has been the subject of debate for some time now, and I don't have a strong opinion either way. And, yes, you should do both woofers.  A) the other one is fatigued, and B) this is the only way they'll sound the same.

When this is completed you'll still be the proud owner of a fully functioning pair of 1971 Large Advents, as close to original as possible.

Good luck!

Millersound in PA are top notch and have been in business pleasing customers for 1,000 years.  Call Bill at (215) 412-7700 and you will be all set.

However, yogiboy's link to simply speakers OEM replacements for $130 is worth looking into.

As mentioned above, whatever you do you will want to do it in pairs.

The woofer is history.

I had a pair of Large Advents of the same vintage and the woofers required repair about 20 years ago.. I'm surprised your woofers lasted this long.

Send both woofers in for repair and you will be fine. If you want to keep them until you die the Simply Speakers replacement woofers are the best fix. The cost is reasonable. Even if you decide to upgrade your speakers, those Advents are collectable and people will pay a surprising amount of money for them if the cabinets are in good shape. I sold mine with repaired woofers for $300 but the cabinets and grills were in perfect condition. I see them selling on eBay for as much as $450 a pair. If the cabinets are trashed it's a matter of how much emotional attachment you have to those speakers. There are hundreds (thousands?) of used speakers available for under a thousand dollars a pair that will sound quite a bit better than your Advents.

Unfortunately, these speakers, as good as they were in those days, are really not very good.  BIG SURPRISE to me when I opened my shop in 1974 and thought they were AMAZING until I put almost any other speaker next to them 

Box speakers have come a LONG WAY since then, no disrespect to Mr. Kloss, so you might be better off buying (even used) a newer speaker than putting money into fixing those.

Cheers!

Bad surround may be the issue & hopefully no permanent  damage has been done., There are a few surround re- foaming kits available on eBay for short $ for the original Large Advents that are worth trying & because there were so many of these speakers sold, there’s probably entire woofers available also. Jensen then distributed & I think made a replacement woofer for it that has no Masonite ring & a black metal frame that is a perfect fit & works very well. I owned a few of the Advents back in 1974 ( one pair & then a stacked pair) & again later on in the 90’s ( left in a home I bought!). 
 

I blew a few woofers playing them at stupid high levels but overall they’re were a great speaker in its day for $210 /pair in Walnut cabinet). For the equivalent & $1200 or so today, there are speakers w/ better high end & image better but few if any w/ better bass. They are warm & musical & their faults are more omission than commission.  Get them fixed & enjoy a true classic!
 

The LA of 1974 would have a Masonite ring with a 9” paper cone in a 12” basket, designed that way specifically to prevent bottoming.  So either the inverted foam surround is perforated or there is another air leak somewhere…or you are overdriving them.  They should handle a 125W amp easily, but you may have more.  Are you boosting the low end?  Don’t. People used to stack pairs to increase their output.  They had impressive bass but there are limits!

Yea, if the speaker driver is 50 years old, it probably needs new surround’s, however you can get replacements online usually at pretty good prices. Check out Dayton. I’ve used their woofers in projects a couple of times and been very happy.

All the best.

Uh, considering they're almost 50 yrs old you may want to consider buying something newer ...

Uh, considering they're almost 50 yrs old you may want to consider buying something newer ...

Here ya go!

 https://www.simplyspeakers.com/advent-replacement-woofer-p001-31858.html

Before surgery/replacement try rotating the faulty woofer 180 degrees.

The woofers also need to be sealed to the cabinet (it's a sealed system and any air leakage will increase the woofer's travel distance/excursion).

Once snug the bolts should be tightened systematically and gradually (like tightening up the oil pan on a car).

I don't know what would be good to seal them with (RTV silicone?) but others here should know.

DeKay

Turn the volume down you're overdriving the woofer voice coil.

Mike

@vcheney The suspension of the woofer is probably done in. You can get it rebuilt at a speaker reconing service. I would google it to see if one is in your area. We have one here in Roseville Minnesota that is quite good and been around for over 60 years. If that one is bad the woofer in the other channel likely isn't far behind.