New Large Advents refoam question

[Mystery]

Got used NLA's with bullnose woffers and surrounds are gone.

Ordered a kit from Rick Cobb and it's on the way.

I've never done refoam before.

The kit supposedly comes with a CD that has 30hz tone.

Using that, there is no need to cut dust cap as it aligns the voice coil.

My question is, how loud should the 30 hz tone be?

Should it move the woofer little bit or just be unnoticeable?

The NLA woofers are rated from 32hz and up. Will playing 30hz tone damage them?

Thanks for sharing your experiences.

[Carlspeak]

The resonant frequency of the woofer is lower than 30 hz, so the test tone will work fine. Adjust the volume so you can hear it and notice the woofer cone being centered.

To re-assure yourself futher, do a search on youtube of refoaming. I'm sure you'll find a number of good videos of folks doing exactly what you are planning to do.

Good luck!

[ironlake]

I turned the volume up so the cones were just short of doing there maximum excursion so the voice coil would get center on the full excursion of the speaker. Works super.

[Mystery]

Refoam in progress...

Cleaned old surrounds last night and glued the inner lip of the surrounds.

Left them overnight and today morning glued the surrounds to the baskets.

Few issues:

1. That glue gave me headache.

2. I glued the inner lip of the surrounds too much deep in the cone. I tried to glue the surrounds convex area all the way upto the cone. I should have left some of the inner lip beyond the cone but it's so small and hard to decide how much to glue. It's not that bad as the outer ring still goes to basket all around.

Lesson learned: don't use all the inner ring to glue in to the cone.

3. Instruction mentioned to play 30hz tone loud enough to move woofer between 1/8 - 1/4" but I found it very difficult to get that accurate movement. I just guesstimated looking at the cone from under the basket.

I didn't turn the volume to get too much excursion as per instruction and also I read the post here after I started refoaming.

Hopefully, it's centered.

4. The outer rings came apart in few places while playing the tone and had to re-touch few times and used little too much glue.

Result:

Overall, I don't hear any voice coil rub on this volume level (1/4" excursion). BTW, what's the max excursion of these woofers???

I do hear some ground loop noise and some vibration noise but no scraping, no rubbing.

It's good use of 2 hours or more to re-foam if you have nothing else to do but I'll be happy to pay $20 bucks for someone else to do that for me.

It was fun learning experience. Let's see how they sound.

It's still playing the 30hz tone for next 1/2 hour.

I also ordered DeOxit kit that should be here in few days. Once I get that, I'll clean the oxidized speaker contacts and also check the L-pads that has one loose binding post. Until that, the woofers will be sitting out of the boxes.

[Mystery]

Done...

Large Advents are back to life...

I find these much brighter than other speakers I have.

The tweeter control on Normal and Extended makes them brighter than I am used to. When turned to 'Decrease' position, it cuts almost all high and sounds too dull.

May need to get used to egg fried tweeters.

I also fixed the binding post that was loose.

It won't move anytime soon now.

The washer was not holding the screw correctly.

Some pics of finished project below:

[JKent]

Congrats.

You might want to try Pete's "BSC." He has a loaner you can try out and if you think it helps, construction is very simple. I built one yesterday after trying the loaner. It could make the Advents sound smoother.

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=4686&hl=%2Bbsc+%2Bloaner&fromsearch=1

Kent

[Pete B]

Done...

Large Advents are back to life...

I find these much brighter than other speakers I have.

The tweeter control on Normal and Extended makes them brighter than I am used to. When turned to 'Decrease' position, it cuts almost all high and sounds too dull.

May need to get used to egg fried tweeters.

I also fixed the binding post that was loose.

It won't move anytime soon now.

The washer was not holding the screw correctly.

Some pics of finished project below:

Decrease on these is just a level drop on the tweeter, if the tweeter

seems to shut off completely then one of the resistors is open in the

crossover.

I strongly suggest that you try the BSC if you'd like.

[Mystery]

Congrats. You might want to try Pete's "BSC." He has a loaner you can try out and if you think it helps, construction is very simple. I built one yesterday after trying the loaner. It could make the Advents sound smoother. http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=4686&hl=%2Bbsc+%2Bloaner&fromsearch=1 Kent

I'll read the BSC thread but may not work on it right away.

From experience, how much is the cost for BSC?

Also, does it work only on NLA or other speakers?

Decrease on these is just a level drop on the tweeter, if the tweeter seems to shut off completely then one of the resistors is open in the crossover. I strongly suggest that you try the BSC if you'd like.

Hmmm... tweeter level drops on both speakers in the same way on decrease switch.

I see only one resistor connected to decrease switch.

I'll take the woofer out and check them out.

From what I found online, they should read either 1.5 ohms or 1 ohm but isn't 1 ohm reading suggest open anyways?

Also, another issue I ran into is the screw crumbles more and more mdf particles each time I take woofer out and put back in.

Is there something simple to make mdf particles solid in the holes?

[JKent]

Pete is the expert on the BSC but it's really cheap. You need a small project box (there are photos in the thread), 4 RCA jacks, about 8" of wire, 4 resistors and 4 caps. I made the 6db version so the parts were:

R1 4.7K

R2 4.3K (not a common value--you could use 4.7K)

C1 0.0047uF

C2 0.068uF

I happened to have all the parts on hand except the box (like this: http://www.parts-exp...tnumber=320-410 ), which I bought locally for about 3 or 4 bucks. Guess if you had to buy all the parts it'd run maybe 10 bucks or so.

You install it in a tape monitor loop, external processor loop, or between the preamp and amp. If installed in a loop you can easily switch it in & out to evaluate it.

It does work on other speakers. If you get the loaner from Pete, it has a switch for different settings. Pete noticed it worked well with AR2ax's and I'm using it with some mini speakers that I built from scratch. Nice thing about the loaner--Pete generously lets CSP members borrow it to try. Your only expense is return postage.

One fix for the crumbling particleboard would be to scrape away any loose stuff, put a piece of tape on the back and fill the hole with epoxy. After it cures drill holes for the screws. Another trick would be to glue matchsticks in the holes.

btw--I assume you've seen this thread: http://www.classicsp...topic=6623&st=0

I built the "super crossover" with guidance from Pete and if you look at post #33 it shows the xo and also the cabinet braces, inspired by Carl. You may want to brace your cabinets. It's very easy. You can use an old broomstick or scrap wood. Two front-to-back braces were easy to install and the screwheads don't show because they are in the front baffle and the back of the speaker.

I was disappointed that I didn't love the OLA. They sure LOOK nice and I dumped a lot of money into them. Trouble is I compared them to my AR 91s and AR3a's--both much more expensive speakers so not a fair comparison. Don't get me wrong--the Large Advent is a really nice speaker and was probably the best available in its price range. Also, I had refoamed the OLAs and I'm sure the new foams need a little time to break in. After a week or so the OLAs were sounding better!

But I'll keep my ARs.

Kent

[Mystery]

Thanks for great information Kent!

I will think about the crossover and braces.

This is my first pair of Advent, 2nd is Advent Prodigy Tower.

Still on initial listening phase. Not sure yet whether to keep or sale but if I like them, I'll definitely try few different upgrades.

BTW, I had a chance to pick up AR-4ax for less than fifty, but passed as reviews were not so great on that model.

[JKent]

those capacitors are pretty old. Replacing would be a good idea. And you may as well do the resistors to be safe. They are 35 cents each at Erseaudio. For the NLA you're talking about one 13uF cap, a 1 ohm resistor and a 1.5 ohm. No need to replace the inductor. Pete has a schematic here: http://baselaudiolab...VENT_LA_XO.html

btw--I'm not familiar with Rick Cobb's kits but the glue from MSound will not give you a headache (literally OR figuratively). The Flared metal frame Advent woofer is a bit of a pain to refoam. I've refoamed several AR Advent, Rectilinear and other woofers, but the metal frame Large Advent woofer likes yours was the most difficult. I'm also not a fan of the 30Hz tone. Shims work.

Another concern: You wrote "I glued the inner lip of the surrounds too much deep in the cone. I tried to glue the surrounds convex area all the way up to the cone. I should have left some of the inner lip beyond the cone but it's so small and hard to decide how much to glue. It's not that bad as the outer ring still goes to basket all around." I'm a bit unclear on this. Maybe your woofers are not working right because the foam is incorrectly glued on. Maybe not. I'm just not sure from your description. Looking at your photos, they do "look" right.

Nice thing about the MSound glue--you can pull the foam off and start over if it's not right. If your kit used the solvent-based glue, that's not forgiving at all.

Where are you hearing vibration? There should be none in the speaker.

Kent

[Mystery]

The vibration is I think from the woofer itself when I use 30hz tone in quite high level and the woofer moves a lot.

I'll check out erseaudio and upgrade links.

I thought the inner lip thingy again and it looks okay .

Thanks for all the info.

[Pete B]

Nice work, good that you didn't cut the dust caps and shim. The dust cap is critical to maintaining the midrange performance,

especially since it is a two way and the woofer has to reach so high.

It is difficult getting the foam edge height correct with the NLA woofers since there is some give as to where you glue the foam

on the lip of the frame. I first checked that the new foam I was using was of the same dimensions, then I measured down from

the frame edge to see where the original foam was placed and made a guide by marking a line on a business card. I used the

guide to help position the new foam on the frame. I discussed it here but had some trouble finding this thread:

http://www.classicsp...?showtopic=2842

[Mystery]

Thanks for the post Pete.

The links on that other thread are broken.

That's interesting. I never even checked whether the cone was in level or not. I didn't even make a note of original surrounds as most of those were gone anyways.

For my home use, they sound good and have not bottomed out yet even at pretty good movie watching levels.

When I used 30hz tone, I am sure the cone moved a lot more than 1/8" up and down.

I think it moves around 1/2" when I visually inspect it or physically touch it.

Hmmm... if the cone is suppose to only move 1/8", I should think of listening at very low levels.

So far I have less than $50 invested on this pair and so far so good.

Next is caps/resistor upgrade.

I saw some very cheap caps and resistors like 50 cents each online.

Do they work the same as some expensive ones from Solen, Clarity etc.???

I read that caps for mids/woofer can be cheap but NLA has only one cap.

Is it for woofer or tweeter?

Also, will replace binding post with something that accepts banana plugs.

Looks like I have to take the crossover board out as one of the binding post is under it.

Do I just yank it out or is there a good tool to use?