Baby Advent II speakers review

[bluepine27]

Got the kit today and working on scrapping the old foam right now. Had some questions: So I have the outer rim of where the surround would go, cleared out of old foam and the old adhesive. The only bumps I feel I think are from deepish scrapes into the metal frame rather than foam or adhesive.

The inner rim where the cone is has a layer of adhesive all the way around that I wouldn’t be able to scrape off without hurting the cone I think. Also read re-adhering to old adhesive was fine.

Should I continue to feel this inner rim for foam pieces? And also hit the outer rim with alcohol just to make sure it’s as smooth as possible?


Also is it fine that the gasket piece has some of itself missing from the bottom ? Taking it off peeled some of the bottom but is still well intact. Will scrape the old foam off of this as well before glueing it back on.

Any other recommendations would be welcomed

 

[bluepine27]

I actually used my thumb nail and scraped the outer rim of the cone and got the adhesive/old foam off more than previously posted. Kind of scrapped away some cone material though, is that ok? It’s not super smooth at some parts but I think the only material left on the cone are bits of adhesive and the cone material itself. What’s the ideal scrappage here?

 

[WillMeyer]

I doubt you'll get it much better than that on the cone.
I typically use a wood chiel that I bought cheap at Harbor Frieght.
The scraper cleans the cone well; mind you I'm gentle in my application of the scraper and support the cone from behind in the area I'm working in.

Also in regard to the "gasket". I think you are talking about that paper laminated trim ring. If so, don't worry about that. Its just a trim ring to pretty up the speakers a bit.

The higher end Advents (Maestros, Heritage, Laureates and a few models of Prodigies) have that laminiated paper trim ring replaced with a plastic trim ring (in the case of the Laureates it actually a closed cell foam).

Once you are done with the refoam to you satisfaction, you just use a little glue to afix the trim ring. It hides the open frame that is typically all scratched use from the cleaning process.

 

[Ruben Acosta]

I've started checking out mine but the woofers are in great shape. One of the tweeters dome was crunched in a bit but it sounds the same as the other. I don't like the looks of the crossover. Why would you use an electrolytic that's only 2.5 uF? They work ok but it clear these are even less efficient than my Rectilinear IIIs! By at least 6 db! I'll try a different crossover to see if it improves.

 

[Fred DuBuron]

As would have it...
I am working on a set of Baby Advent Woofers in the workshop this week...
They are not finished yet... but I thought I would share the pictures of where they are at and comment.

The paper gasket is in the background and will be cleaned up a bit and reused. Yes, you will lose a bit of the bottom paper layer. It will still glue back down and look fine when you are done (Last Pic)

I also use a wood chisel to clean the frame edge. I keep a whetstone handy to restore the chisel edge as I work. A small Mechanics Gasket Scraper also works well. I clean the edge of the paper cone with a sharp utility knife held verticle to gently "SCRAPE" the glue. DO NOT TRY to scrape at an angle as it will cut the paper. SCRAPE IT by pulling the vertical knife-edge toward you in small strokes. You will know when enough is enough. The loose glue will stop coming free. My next step (not done yet on these) will be using a wire brush to clean up the edge and some 100 grit sandpaper to smooth it all out

The dust cover in this one was badly dented and I used a Shop-vac... with a radiator/crevice cleaning tool... and some rubber vacuum hose to create a leaky setup that I can regulate the amount of suction with. I use the vacuum hose to gently suck out the BIG dent. I now have three small stress dents where the dome was creased a bit.




I can usually get these out by using a small wooden skewer with a drop of contact cement on the end. I use the drop of cement to let the skewer set up for a minute in the dent and then gently pull the dent out. The contact cement can then be pulled off the dust cover with a scratch of a fingernail or an x-acto knife BEFORE IT SETS HARD. I will be able to get all three of these dents completely removed using this method.


In this pic I just threw the foam surround on with the ORIGINAL paper gasket to show what the end result is going to look like. I also have a small can of black/grey paint the I touch up the screw hole when done using a thin artist's brush to knock down any shiny metal. On larger Advents, I have both an 8" and 10" round masking template made out of card stock to mask the surround and speaker cone so I can paint the frames just outside of the new surrounds to cover any metal.

I also prefer to use the WHITE GLUE on foam surround over the other adhesives as they tend to set too quickly, bubble up along the edges, and expand as they dry. The white glues make it easier to adjust the surrounds, dry clear and do not bubble up. Any white glue easing out of the surround can be wiped up and if needed scraped clear with a knife before it drys. Using fingers to clean up oozing glue on the paper cone is a NO-NO. It will smear and ruin the overall "look' of the finished product. Applying LESS GLUE IS BETTER!!

CONTROVERSIAL
A trick here with the white glues (water-based) is that you can use the glue diluted (30% glue to 70% water) to gently coat a speaker cone that has dried and become too "aged". DO NOT OVER WET THE PAPER!!! or you will ruin the paper cone. Just one application with a damp (NOT SOAKING WET) brush. Cone will have a nice satin-like finish when applied correctly. The trick is to not increase the overall mass of the cone with a heavier coating. You want to return the paper cone to a like-new surface that will interact with air to properly reproduce the sound waves as it did when new.

 

[Skywatcher]

I actually used my thumb nail and scraped the outer rim of the cone and got the adhesive/old foam off more than previously posted. Kind of scrapped away some cone material though, is that ok? It’s not super smooth at some parts but I think the only material left on the cone are bits of adhesive and the cone material itself. What’s the ideal scrappage here?

You're doing great. A couple small spots are no big deal. The new glue will adhere to the old glue just fine. A few "bumps" in the surround is also not a big deal and you'll barely even notice them if at all once it is done. If the cones feel too soft, I use Mod Podge matte finish and put a thin coat on. It's basically the same as @Fred DuBuron did with diluted water based glue.

 

[Skywatcher]

I've started checking out mine but the woofers are in great shape. One of the tweeters dome was crunched in a bit but it sounds the same as the other. I don't like the looks of the crossover. Why would you use an electrolytic that's only 2.5 uF? They work ok but it clear these are even less efficient than my Rectilinear IIIs! By at least 6 db! I'll try a different crossover to see if it improves.

Gotta watch changing the crossover point. 2.5uf stops lower frequencies from blowing the tweeter and transitions from the woofer to the tweeter. Changing the cap to a new 2.5uf film will brighten it up though. Beyond that, a more efficient tweeter would be needed if you want "louder".

 

[bluepine27]

The refoam job was a success!

thanks @WillMeyer and @Skywatcher for the confidence boost and technical guidance.

sounds really good. Noticeable comparison to the other speaker which still has the old surround. Bass feels more detailed, with oomph, moving air and old one sounds a lil more dead and flat in comparison.

with that being said, nothing is wrong with the old surround in the other yet, still intact but definitely has a more faded, rotten look and sounds a bit more dull compared to the new one in the other speaker.

should I switch the old surround out before it really starts to blow or is waiting for it to actually sound bad fine?

if both are playing at the same time I don’t really notice the left side bottom end sounding a lil less present. I had to A B them for awhile but to really notice. Or push the bass pretty hard, harder than regular listening to hear it being more dull.

Sent a picture of both and a picture of the other one I haven’t done yet.

 

[Ruben Acosta]

Gotta watch changing the crossover point. 2.5uf stops lower frequencies from blowing the tweeter and transitions from the woofer to the tweeter. Changing the cap to a new 2.5uf film will brighten it up though. Beyond that, a more efficient tweeter would be needed if you want "louder".

I screwed up the cap is 3 uF but tests to 3.3 uF. The OEM crossover is much higher than 2500. I made one up to about 3100 Linkwitz-Riley. It was lower than OEM. I'm thinking that review I read was older than mine. The only thing to identify this speaker is perhaps this pic on the back. Perhaps the number stands for 1985.

 

[Fred DuBuron]

I use Mod Podge matte finish and put a thin coat on

Interesting... I worry about some cone mixtures "cracking" or flaking off with age.
Whatever you end up using, if you have an old speaker cone practice on it until you have the right look and feel, Never "SOAK" a paper cone. Use a damp brush rather than a brush dripping with the mixture to just surface coat the cone.

 

[Ruben Acosta]

I have evaluated these OEM crossovers in the Baby Advent and they have 4 components, I will include Pics, with the largest iron core inductor being about .88 mH for the woofer, a 3uF NP electrolytic cap that tested 3.34 uF and smaller iron core inductor of .34mH and a 2 ohm 5 watt ceramic resistor, all for the tweeter. So just looking at it they put a 6 db/octave coil for the woofer which from calculator from DIYAudioandVideo.com comes out to about 1400 Hz as a Butterworth. The tweeter was a 12 db/octave Butterworth that was around 4700 Hz. They changed this because I have seen KCS crossovers that had only 3 components which was 6 db/octave for both. The tweeter needs more protection than the woofer. I liked the sound I had making a 12 db/octave Linkwitz/Riley crossover for it at 3100 Hz but I was only using some extra components I had. I don't want to buy these components and build my own crossovers for it. But I do think I will replace the NP cap with some small Mylars I have. I verified these crossover using tone generator. I bought these new back in the 80s and so they have worn well and proven reliable.

 

[Skywatcher]

Interesting... I worry about some cone mixtures "cracking" or flaking off with age.
Whatever you end up using, if you have an old speaker cone practice on it until you have the right look and feel, Never "SOAK" a paper cone. Use a damp brush rather than a brush dripping with the mixture to just surface coat the cone.

I soak them pretty well sometimes to no harm whatsoever. The Mod Podge and/or glue rebonds the fibers back together to stiffen up the paper. The key is to make sure they are thoroughly dry before touching them. I have also had to straighten deformed cones by thoroughly wetting the paper, propping them into shape, and let them dry.

 

[Skywatcher]

I screwed up the cap is 3 uF but tests to 3.3 uF. The OEM crossover is much higher than 2500. I made one up to about 3100 Linkwitz-Riley. It was lower than OEM. I'm thinking that review I read was older than mine. The only thing to identify this speaker is perhaps this pic on the back. Perhaps the number stands for 1985.View attachment 2150682

3.3uf is within the +/- 10% tolerance so a new 2.7uf to 3.3uf film would be just fine and keep it very close to original. But I think that's part of the "hobby" to mod things to suit your own ears.

 

[Fred DuBuron]

I soak them pretty well sometimes to no harm whatsoever. The Mod Podge and/or glue rebonds the fibers back together to stiffen up the paper. The key is to make sure they are thoroughly dry before touching them. I have also had to straighten deformed cones by thoroughly wetting the paper, propping them into shape, and let them dry.

I had never had the guts to try that...
Good to know... Have you ever photographed (Before/After) your process? I would love to see your process.

 

[Skywatcher]

I had never had the guts to try that...
Good to know... Have you ever photographed (Before/After) your process? I would love to see your process.

Nope, never took photos. I don't actually have a set "process", but just wing it. Different cones are usually different depths, and the cones a differing angle. I'll use whatever I can find to make a "jig". Sometimes a certain saucepan works, sometimes I use poly cones as the "form" (if they fit properly) and as the "press" to hold the paper cone in shape until it dries. Sometimes it's just a matter of a slight "squeeze" to get the cone round again. You just gotta use your imagination. Non-pressed pulp shouldn't be "pressed" into shape, just "nudged". Pressed paper cones can be done either way, pressed back into shape or not. They're paper, just like anything else made of paper. When paper is wet, it is weak (think wet paper towels). That's why you must be sure a cone is thoroughly dry before touching it. A paper towel once dried, is just as strong as it was before getting wet (minus the crumbling from using it while wet). You won't be "crumbling" a wet cone unless you have a "whoops!" moment.

 

[Liuchan]

I have changed my baby Advent and mini Advent speakers with audio grade 3.0uF capacitors. Each speaker match to less than 1% crossover frequency. The tweeters sounds much crispy and clear than before changing. I have checked old capacitors and the differences are about 10%. I am amazing the sounds are improved by matching left and right speakers.

 

[N8Nagel]

I have changed my baby Advent and mini Advent speakers with audio grade 3.0uF capacitors. Each speaker match to less than 1% crossover frequency. The tweeters sounds much crispy and clear than before changing. I have checked old capacitors and the differences are about 10%. I am amazing the sounds are improved by matching left and right speakers.

I think some of it is matching and/or returning the crossover frequency to its design value, but I think some of it as well is the capacitors inline with the tweeters going high ESR as they age; both KLH Twenty Threes and Rectilinear IIIs IME *Dramatically* improved with new caps, they were warm and wooly before, well the KLHs will always be a little laid back but the Rectilinears were like a completely different speaker with some new caps in them.

 

[Dabidoh]

I obtained a pair of Baby Advent II speakers as a repair project for a friend. Turns out they'd been re-foamed off-center and a woofer had jammed at the bottom of its excursion. Here's how I fixed them:
http://davesanborn.blogspot.com/2021/09/advent-speaker-repair.html

 

[ukedude]

Hi,
I have a pair of these that I refoamed recently and they sound great—no plans to change out the any other parts. Does anyone have a recommendation for an amp to pair these with? I have a second-hand Marantz, sadly with a cooked transistor and circuit board, and do not want to go the second-hand route again. I was thinking about the NAD c316bee. Too much power? The Cambridge AXA 35 seemed ok, but the folks at CA said not to use it with 6 ohm speakers… s Suggestions in the under $500 region welcome. Source is a Mac Mini and Schiit Modi and sometimes a Yamaha tape deck.
Uke

 

[bigaltx24]

I used to have to travel a lot for work. 0ne day after a three hour stint. I pulled into a small town in Mississippi, I needed to get gas and stretch my legs. Found a gas station, while I was pumping gas I saw a antique store across the street, I figured that would be good for some walking. Didn't really see anything that I was interested in until I saw two boxes of Baby Advent IIs that hadn't been opened. I asked the guy what he wanted for them. He said $20, he told me he had bought a full estate about two years back, and they had been sitting on that shelf since then. He said he didn't think he would ever get rid of them. I handed him 20 bucks and walked out with a brand new pair of Baby Advents.When I got home I opened up the boxes, figuring they would need new surrounds. They were in plastic bags and to my surprise the surrounds where still intact. I hooked them up to my Nacamichi Sr2a and was surprised at how good they sounded, great little speakers. I listen to them every now and them. They always bring a smile to my face every time.