Reviving some Advent Minis

[MuseChaser]

I have five of these that all need their surrounds done. Four of them are from one "batch," I think, and I picked up a fifth to use as the center channel for a matched 5.1 set in the bedroom system. I've done one from the original set of four, and just did the solo one I picked up a week or two ago.

The questions aren't regarding doing the surrounds.. I've done a bunch of surrounds prior with good results.

The single Advent differs from the other four in a couple ways. It has a slightly earlier serial number.

1. Hex screws used to affix baffle rather than JIS or Phillips heads on other four. Not a fan. It was a 3.5mm and I had to go through a bunch of my hex keys and bits to find that size. No big deal of course. Tweeter is glued in upside down on it's plate, compared to the other speakers.

2. Different crossover component manufactures, at least visually. Even with almost half of the surrounds missing on some of these speakers, they still sound amazingly good so I don't feel a need to mess them. Just curious if there was a change at some specific point, or if swapping in whatever was available during a run was common practice. Too much goop to tell what the values are visually.



3. Embarrassing question, because I know the answer... "everything matters, and ported speakers need to be sealed at least as carefully as sealed enclosures"... but ... well... going to ask anyway. These speakers had optional wall mounting brackets available when sold. Three of the five have them, and two don't. The threaded inserts indicated by the yellow arrows above are where the mounting brackets bolt to the speaker. If I don't wish to use the bracket, will there be a noticeable difference of any kind of I DON'T caulk or otherwise plug them? The two that don't have brackets just have a thin paper label covering entire area with the four mounting holes in the corners.

4. This one, I believe, has been re-surrounded before, and not very well. The way the voice coil wires are mated on the cone looks weird, too, as if they were spliced. In any case, the driver works thankfully. However, getting the old adhesive off, which was really dry and required a lot of alcohol, was a chore. Between the roughing up of the cone the last person did, and a bit more I did, there's some pretty rough spots where the paper isn't smooth any more. The worst spots are circled below.



Anything need to be done? Light doping with something? Let it go?

Thanks for any input. I'm knocked out by these little guys. Didn't expect this kind of warmth.

 

[Nat]

If you want, put a dab of white glue on the the dings in the woofer and in the holes in the threaded inserts. Probably won't make much difference, but it may ease your mind, and that actually matters.

 

[Lavane]

As for #2, many speaker manufactures used whatever was available for electrolytic and even film cap brands. I've seen various crossovers from the same model speakers having different brand electrolytic capacitor mostly.
And in some instances a different brand film cap is used. You could just go with a new axial electrolytic or even replace it with a polypropylene film cap of your choice. I usually replace electrolytic caps with film caps. Mostly Solen, Mundorf, Audyn, qnd Dayton. Film caps can be physically larger than an electrolytic though. Sometimes you have to get creative. Like the picture below of some Polk crossovers I recapped.

 

[Lavane]

Here is a crossover that I recapped from different same model speakers. Notice the inductor is different from the above picture, along with the one original film cap. Mine were blue, these were yellow.

 

[MuseChaser]

Finished up two more of the five today. One to go.. I ordered the extra surround later than the others and it'll be here tomorrow. I know there's a ton of FluTube videos out there and other sites showing the process, but didn't see one specifically for the Minis, not that it's any different, really. Anyway, for anyone interested, I snapped some pics as I went today. Here's the run down...

As received. The first two I did were in even worse shape.. huge gaping pieces of foam were missing.



The two crossover components mounted on the back of the input jacks, after removing the one piece of fiberglass stuffing....



...and the back of the front baffle...




The drivers removed...



... dried foam removed with fingers, scraped from basket with boxcutter carefully...



...then after using lacquer thinner to remove traces of glue from basket and tons of lacquer thinner soaked Q-tips to remove foam debris and glue residue from outside of cone. Better to not get too rough here... just get the foam off and a nice flat surface; don't worry if it's still tacky. Go too far, and you start to degrade the paper.



Laying the new surrounds on for a test fit. Note some light overhang, and that the baskets are not symmetrical.. the flanges on opposing sides are a bit wider than the other pair of opposing sides. I mark the top, then the start and end of each flange, then just trim away a bit with scissors.



Once the fit looks good, flip the surrounds over, lay a small bead of glue on the inside lip of the surround, spread it for complete coverage of the lip but not too heavy, then place it carefully in position on the cone and press lightly and repeatedly in place going around the cone, opposite sides simultaneously, until it tacks and grabs. I cover my fingers with wax paper so as not to get excess glue on the cone or surround (Works pretty well, and wish I had though of that the first time I did this a few years ago). Let dry for an hour. Patience. Go do something else.



After an hour, work the tip of the glue tube between the basket and the surround and run a small bead under the surround all the way around. Tap the surround down onto the glue to spread it (wax papered fingers). but DON'T keep pressing it down immediately to the point that it sticks. This, other than prep, is probably the most important part....now go around as you did before, pressing the surround to the basket and getting it to grab, but stop frequently and "exercise" the driver, using three or four fingers all around the cone to gently depress it and letting it rebound to find its center, then press on the surround some more, then exercise the driver again... repeat until the glue has setup well. This ensures that the driver stays centered in the voice coil. The surround may have a few ripples in it, but they'll smooth out as things dry. here's what mine looked like immediately after this step, but before drying...



On the Minis, there's a ring on the inside of the baffle that seals right up against the surround lip, so if you DO get one small area that doesn't glue perfectly, it likely won't matter, but you won't have any trouble with the glue. It works great.

Here's the finished set. I can't believe how good these things sound.



edit/note: just looked at the pics closer... any weird off-center looking placement of the drivers in cutouts, or surrounds on drivers, are an artifact of really bad parallax on my cheap phone.