Strange issue with tweeters on advent loudspeakers

[Laricc]

I checked out the trick to move the control switches, but that doesn't seem to be the problem. The sound it was producing has gotten worse, as it now sounds more like an electrical buzz that can be now heard in both the tweeter and the woofer.

My best guess is that it may not be the tweeter, so that can be ruled out. Another thing is I swapped their places and the sound seemed to just stop...though something still seemed off. I then adjusted my monitors to run them into my other carver unit, and the electrical buzz seemed to of stopped in that speaker. I'm not sure why that would even happen, seeing how I used multiple types of speakers on my other receiver and they never seemed to of had an issue. I might do some more troubleshooting to see what was causing it.

One thing I noticed on the back of the speakers, was one node having the 8Ohm stamp while the other simply had 0. I suppose the 8ohm corresponds to the (+) node, while the 0 corresponds to the (-)?

Small update: I swapped the wires to the B deck on the original receiver and the sound seems to of cleared up. I'm going to wait a little bit to see if it was actually just the receiver.

 

[Guido57]

yes, the 8 ohm can be considered the +. The buzz may ( or may not) be a poor connection somewhere. What about the original problem? Is that gone? It couldn't hurt to follow classic carl's advice on hitting those switches with de-oxit, it is good advice.

 

[Laricc]

yes, the 8 ohm can be considered the +. The buzz may ( or may not) be a poor connection somewhere. What about the original problem? Is that gone? It couldn't hurt to follow classic carl's advice on hitting those switches with de-oxit, it is good advice.

I may go and pick up some...I honestly been needing to get some for quite some time. Overall there may have been something up with the A deck. I'll see about it tomorrow. So far they have been handling well throughout the day...I'm glad to say that the refoam was a success!

Also, if you see this Doug, thanks for suggesting that refoam trick! I did it a bit differently, and also got some help. In the end, I used the rubber solvent glue, and it came out surprisingly clean. I had the surround seated below the cone first, then lifted up the cone and applied the glue between the gap onto the inner surround flange, and simply set the cone back down once the bead was set. That seemed to work well. When it came to centering the cone, I just did the 30Hz trick and it seemed to of lined up well.

One thing I have noticed is that air seems to leak through the seams around the subwoofer, or through the screw holes. This creates a strange sound as I can hear the air trying to escape through those parts.

Is there anything that I could inlay on the inside of the woofer to stop this from happening?

Thanks to everyone who shared their advice!

 

[Doug G.]

I have done the inner flange your way, too. It's just a bit easier for me to do it with the surround flange on top first. Then, you don't have to hold the cone up. That's fine, though.

The woofer flange must be completely sealed and airtight between it and the driver opening. There can be NO leakage there. The speaker response will be totally messed up if that isn't accomplished. I and many others use a product called "Mortite" to do this. It is similar to what Advent originally used. It is available in most home improvement stores. It's a rope-type caulk. I even use it in place of the very thin gasket on the all-metal woofer as that often isn't thick enough to seal all irregularities after a driver has been disturbed.

The essence of an acoustic suspension speaker is that the enclosure is airtight. The only leakage allowed is the small, controlled, leakage around the voice coil/spider area. The trapped air in the enclosure controls and restores the cone position and not the mechanical structures of the low frequency driver.

Doug

 

[Laricc]

I have done the inner flange your way, too. It's just a bit easier for me to do it with the surround flange on top first. Then, you don't have to hold the cone up. That's fine, though.

The woofer flange must be completely sealed and airtight between it and the driver opening. There can be NO leakage there. The speaker response will be totally messed up if that isn't accomplished. I and many others use a product called "Mortite" to do this. It is similar to what Advent originally used. It is available in most home improvement stores. It's a rope-type caulk. I even use it in place of the very thin gasket on the all-metal woofer as that often isn't thick enough to seal all irregularities after a driver has been disturbed.

The essence of an acoustic suspension speaker is that the enclosure is airtight. The only leakage allowed is the small, controlled, leakage around the voice coil/spider area. The trapped air in the enclosure controls and restores the cone position and not the mechanical structures of the low frequency driver.

Doug

Ohhhh! I saw a bit of clear caulk on the backside of the woofers, but most of it was eroded. I suppose I'll look into getting some of that stuff. It's also known as caulk cord rubber?

My next issue though is the screws. I'm pretty sure air is leaking through them, and some don't even hold the woofer tightly anymore. The only trick to fix that, by what I could guess, was the toothpick trick.

Since this isn't exactly like working with pneumatics, I suppose that Teflon isn't the best thing to use?

 

[Doug G.]

Any rope type caulk that can be manipulated like clay should work. Get some that's not oily, however. That's why Mortite brand is perfect. Just lay about a 1/8" - 1/4" "rope" around the flange and install.

I have used the toothpick fix. Others have installed those "T" nuts, I believe they are called, and used machine screws instead of wood screws but I like to keep things original.

Doug

 

[Laricc]

Any rope type caulk that can be manipulated like clay should work. Get some that's not oily, however. That's why Mortite brand is perfect. Just lay about a 1/8" - 1/4" "rope" around the flange and install.

I have used the toothpick fix. Others have installed those "T" nuts, I believe they are called, and used machine screws instead of wood screws but I like to keep things original.

Doug

The toothpick trick has been my go-to for wood, but the issue is the screw hole basically lost all of it's threading, turned into dust...Even with a few toothpicks, it doesn't hold the speaker in tightly.

Not only that but there's also a hairline crack leading up to it, is it possible that could cause problems in the future?

https://www.parts-express.com/1-4-20-t-nuts-50-pcs--081-1075?utm_group={group}&msclkid=ba0a9ee9b2cf195715e8c0650be338ea&utm_source=bing&utm_medium=cpc&utm_campaign=_Shopping(BSC)&utm_term=1100401923696&utm_content=All Products

Huh...Well, look at that. Found one on parts express just by searching them up.

 

[Guido57]

You can also get t-nuts at most hardware stores, though for 50 pieces that is a pretty low price. Do they sell the 1/4-20 machine screws too? I use them when the original holes are totally screwed up. Does that crack go all the way through the baffle?

 

[Doug G.]

The T nuts would work very well. I don't think you would need 1/4" ones, though. In fact, I doubt those would fit through the holes in the woofer. Yeah hardware store stuff.

I was going to ask the same thing about the crack. If it doesn't go all the way through, probably no big deal. If it does you would want to seal it from inside the cabinet.

Doug

 

[Laricc]

The T nuts would work very well. I don't think you would need 1/4" ones, though. In fact, I doubt those would fit through the holes in the woofer. Yeah hardware store stuff.

I was going to ask the same thing about the crack. If it doesn't go all the way through, probably no big deal. If it does you would want to seal it from inside the cabinet.

Doug

I think it may be, I'll get a better look at the crack. if I have to seal it, would I just use glue?

I'll probably get the screws and the T-nuts from a hardware store since I have a list of supplies I need to get.

 

[Guido57]

1/4-20 is just a very common size, get what looks best. I have had to enlarge the holes for the t-nuts I used, though I don't recall what size they were. It was an extreme case where the woofer wasn't centered in the cut out so one of the original holes had virtually no material left between it and the cut out. I would put something like 1/4 inch plywood behind the crack for reinforcement. Glue it well and clamp it tight until the glue sets. Doug may have other suggestions.

 

[Doug G.]

That sounds good. If the crack is all the way through, it needs to be reinforced, glued, and clamped. Funny how it got cracked there.

Doug

 

[Guido57]

Thinking about it, cracks tend to propagate and the baffles (and backs) of these speakers were particle board, not the more robust MDF of the cabinet sides. I think you should reinforce it even if the cracks are not yet all the way through. The reinforcement should extend several inches beyond the cracks.

 

[Laricc]

That sounds good. If the crack is all the way through, it needs to be reinforced, glued, and clamped. Funny how it got cracked there.

Doug

I'm actually unsure. I got the speakers from a friend who didn't need them anymore since he nabbed himself a pair of DS-50s.
I'll probably ask him when I get the chance.

Also, seems about right with the body being made out of particle board. Any particular glue I should use, or would wood glue just do the job.

 

[Guido57]

Any decent wood glue should do fine. Just clamp well. Took a look at a couple of my Advents, the cabinet sides do not seem to be MDF, but maybe just a better grade of particle board than the baffles.

 

[Laricc]

I got some of the caulk. Sadly there wasn’t any mortite in the stores in my area. This fit the right dimensions (1/8). I suppose you just wrap it around the basket and then seat the speaker back into the cabinet?

I also found some tee nuts and got some screws, (3/4” in length)

 

[Airjmax]

View attachment 1824006

I got some of the caulk. Sadly there wasn’t any mortite in the stores in my area. This fit the right dimensions (1/8). I suppose you just wrap it around the basket and then seat the speaker back into the cabinet?

I also found some tee nuts and got some screws, (3/4” in length)

That caulk is essentially the same as Mortite. It will work fine. I've had more luck packing the caulk around the speaker cutout, making sure to pack tightly around the outer edge. Every one I've done that way has sealed perfectly and passed the push test, meaning that you carefully push in on the cone after the cabinet is sealed. If the woofer slowly rebounds, you have a proper seal. Good luck! I've recapped and refoamed three pairs of Advents. Not too tough to do if you are careful.

 

[Laricc]

That caulk is essentially the same as Mortite. It will work fine. I've had more luck packing the caulk around the speaker cutout, making sure to pack tightly around the outer edge. Every one I've done that way has sealed perfectly and passed the push test, meaning that you carefully push in on the cone after the cabinet is sealed. If the woofer slowly rebounds, you have a proper seal. Good luck! I've recapped and refoamed three pairs of Advents. Not too tough to do if you are careful.

Definitely takes time to refoam...glad I didn’t have to redo them a third time or I think I would of flipped!

So, you sealed yours by putting the caulk around the edge of the cutout for the woofer, and not the woofer’s basket?

 

[Airjmax]

Definitely takes time to refoam...glad I didn’t have to redo them a third time or I think I would of flipped!

So, you sealed yours by putting the caulk around the edge of the cutout for the woofer, and not the woofer’s basket?

Yes, I found that to be the best way after some trial and error. You should only need two "ropes" or sections of caulk packed tightly around the edge. The individual sections pull apart easily. I wish I had photos to show you, but you'll get the idea once you start. You can try packing it around the bottom edge of the basket, but you must be sure that it sticks out past the basket to provide a proper seal.

 

[Laricc]

Yes, I found that to be the best way after some trial and error. You should only need two "ropes" or sections of caulk packed tightly around the edge. The individual sections pull apart easily. I wish I had photos to show you, but you'll get the idea once you start. You can try packing it around the bottom edge of the basket, but you must be sure that it sticks out past the basket to provide a proper seal.

Alrighty, I'll send some pictures when I do start. Hopefully, I'll get to it later today.

I think I'll avoid applying it to the basket since that seems like it would be a bit harder to line up properly versus putting it on the cabinet.