Advent 10" woofer...first generation vs. second generation

[Guest Ken Perkins]

Does anyone know the definitive differences between these two woofers, other than the masonite ring/full frame? Seems the cone, spider and suspension are identical, other than the first generation's inverted surround. I've seen pictures of the second generation woofer with a bumped backplate, which would indicate greater excursion as well.

[Pete B]

Some people add damping to stamped frames to reduce the bell like ringing sound they make when struck. I hear modelling clay works well but I've always just smeared a thick layer of silicone caulk over the spokes. Be sure to let it COMPLETELY dry before putting them back in. Some say that large flat spokes cause reflections back to the cone and one could wrap some wool damping material around them also. Normally I would not worry in a system like the Advents, but I believe it might be worth it considering all the other improvements we've come up with.

I like the raised back plate to avoid bottoming, but have not tried the newer woofer. You say they otherwise seem to be the same, did you measure T&S parameters?

[Guest Ken Perkins]

I used liquid nails to smear all over the spokes of the frame and around where the magenet is attached to the frame to damp my first gen. woofers. Helped alot! Mortite ropes pressed into strategic places works well too. I have always been one to damp the stamped frame of drivers that rang in the slightest.

I just got a pair of the second gen. woofers and am waiting for the foam to get here and get them repaired. They are in VERY good condition being very clean and obviously taken care of. Preliminary comparsions indicated the two woofers (first and second gen.) are identical, except for the frame. Also the voice coil former is not exposed between the cone and spider on the second gen. like it is on the first. Otherwize, the cone, spider and square magnet are virtually the same. The surround is an "outy" and is not inverted like the original, although I doubt this makes a difference.

As soon as I get them refoamed I plan to run the T/S parameters on them and will post.

Regarding the filter, I've decided to pretty much keep it. When combined with my crossover mods, the whole is amazingly good. I was doing some serious listening last night and I must say that for a thiry year old pair of speakers, these old boys could stomp what's out there today. Considering the Advents would bring about $1200/pair in today's money, they would give the competition a run for their money at twice the price.

[Guest russwollman]

>I used liquid nails to smear all over the spokes of the frame

>and around where the magenet is attached to the frame to damp...

>I was doing some serious listening last night and I

>must say that for a thiry year old pair of speakers, these old

>boys could stomp what's out there today. Considering the

>Advents would bring about $1200/pair in today's money, they

>would give the competition a run for their money at twice the

>price.

Now I know why I was chuckling just a bit the last time I left Capitalist Audio and returned home to my old Advents.

I'd like to try your crossover idea, Ken, but I already redid mine.

You and Pete have some up with some great ideas and I admire your application of knowledge—so practical. I'll take your woofer damping suggestions on faith!

There's nothing like getting a lot from a little. The Advents honored that concept at their inception, and thinkers like you continue the tradition!

[Pete B]

I wanted to mention concerning the low bass and Qtc that I noticed in another thread that people mention different types of damping material and that slightly less stuffing was used later in production.

The speakers here have standard pink house type insulation, with the paper removed of course, and they're filled so that it's about 1.5" back from the front baffle when the woofer is removed.

One can experiment with adding say one additional layer behind the woofer to lower Qtc in cases where one is looking for a slightly tighter low end. This might go well with the lower damping of a tube amp or in applications where room gain offers a bit too much lift. I expect one layer to offer a subtle difference, I'll try to get around to measuring it after I refoam the woofers.

[Pete B]

Ken P. wrote:

"Also the voice coil former is not exposed between the cone and spider on the second gen. like it is on the first. Otherwize, the cone, spider and square magnet are virtually the same. The surround is an "outy" and is not inverted like the original, although I doubt this makes a difference."

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I did notice how the former is exposed on the early woofer, but I'm not sure I'm following on the second gen. Does it look like the former lenght is shorter so that the cone meets close to the spider? then the difference would have to be made up somewhere, a shorter frame or longer cone, wouldn't it? The former acts as a heat sink so it would alter the thermal characteristics a bit. Interesting

I was always curious about the "iny" roll edge and later saw it in the very smooth SEAS P17 drivers. The Advent is the only 10" with an "iny" that I can think of. The theory I usually here about "Inys" is that sound reflects off the "outy" causing diffraction ripples in the upper midrange but I also wonder if travelling waves in the cone are better terminated with the "iny" for some reason, perhaps more pressure on the edge of the cone. It would be interesting to measure both.

[Guest Ken Perkins]

Hi Pete,

The voice coil former looks to have been simply chopped off where it was exposed. The frame is the sames depth, as is the cone and magnet structure. A direct comparsion indicates to me they just got rid of this excess aluminum in the former and attacted the cone, spider and voice coil at the same juncture. I'm still waiting my my foam to get here and am anxious to get some T/S measurements on these things.