Speaker Maintenance?

[radiotron_]

I’ve got a pair of Fisher ST-830’s that are really quite decent speakers but need new midrange drivers and they vibrate like crazy when the bass gets deep or I turn the volume up. I posted this over in the “Fisher” forums but got no responses. Is padding or stuffing needed in the speakers, and what midrange driver replacements would you guys suggest? If you want a picture of them, the right speaker is my profile picture.

 

[Silentnet]

Sorry to say it, but "vibrate like crazy" and "quite decent" rarely co-exist. You're likely better off looking for something with stiffer cabinets and better drivers than trying to fix those.

 

[teal'c]

What do you mean vibrate like crazy? You can touch them and feel them vibrate? They buzz? They make some other odd sound?
Why do they need new mids?

If you did a search on these here you already know the reason you didn't get much response, if not it's because these aren't highly sought out speakers. The farther from the 60's Fisher equipment gets the lower the quality.

 

[radiotron_]

What do you mean vibrate like crazy? You can touch them and feel them vibrate? They buzz? They make some other odd sound?
Why do they need new mids?

If you did a search on these here you already know the reason you didn't get much response, if not it's because these aren't highly sought out speakers. The farther from the 60's Fisher equipment gets the lower the quality.

The right channel distorts slightly-might have something to do with the fact the darn dome was pushed in when I got it from the thrift store. Even after I fixed that it’s still got that issue, so why not treat it to some new drivers? By vibrate, I mean the cabinet buzzes or rumbles at louder volume. Sounds like when your drilling a thin board and it starts rattling. This issue is present in both speakers. Sorry for not being descriptive enough

 

[radiotron_]

Sorry to say it, but "vibrate like crazy" and "quite decent" rarely co-exist. You're likely better off looking for something with stiffer cabinets and better drivers than trying to fix those.

At lower volumes they’re quite nice speakers. I think I would just be cheaper to edit them instead of purchasing new ones (I’m more of a budget guy). My old “speakers” were surrounds from some old Optimus system... these are at least an improvement.

 

[radiotron_]

They were only 15 bucks at a thrift store. Oops...

 

[teal'c]

You can help solidify the cabinet with bracing. I haven't had to do it, but looking at those...
I'd put 2 on either side of the mid like so -
And another two in the middle of the sides 1/3 of the way up from the bottom and 1/3 of the way down from the top. Cut them so they fit tight then glue and screw. 1" dowel or 1"x1" square would be my choice.

Have you swapped sides to see if the problem follows the speaker and isn't a problem with your receiver?
Different drivers can be easy, or difficult. If you hit on the correct one right away no problems, but if the sensitivity is too low or too high you can end up with messed up sound. You might be better seeing if you can find one for cheap on ebay. Have you looked at the mid outside the cab? Sometimes there's a liner, foam, or even cups to isolate the mid from the interior cabinet vibrations. If that has come off that can cause distortion with higher volume. It's possible that the speaker has sagged, so you can also flip the speaker 180 degrees to see if that helps.

 

[Grenadeslio]

Try tightening the screws holding the drivers for the vibration issue.

Question, are you using the loudness and cranking the bass? If so then tightening the screws is still a good idea but most likely not your issue.

 

[NH-MAN]

First thing I would do is pull the drivers, and check them and the inside of the cabinet for anything that might be loose.

 

[radiotron_]

You can help solidify the cabinet with bracing. I haven't had to do it, but looking at those...
I'd put 2 on either side of the mid like so -View attachment 1605622
And another two in the middle of the sides 1/3 of the way up from the bottom and 1/3 of the way down from the top. Cut them so they fit tight then glue and screw. 1" dowel or 1"x1" square would be my choice.

Have you swapped sides to see if the problem follows the speaker and isn't a problem with your receiver?
Different drivers can be easy, or difficult. If you hit on the correct one right away no problems, but if the sensitivity is too low or too high you can end up with messed up sound. You might be better seeing if you can find one for cheap on ebay. Have you looked at the mid outside the cab? Sometimes there's a liner, foam, or even cups to isolate the mid from the interior cabinet vibrations. If that has come off that can cause distortion with higher volume. It's possible that the speaker has sagged, so you can also flip the speaker 180 degrees to see if that helps.

These are all great solutions, I’ll try them when I get home tonight, thanks! I was thinking fiberglass inside but they are ported and it would be better to brace them than stuff them. I was reading a thread on a different website about installing new drivers, and they warn against screwing up the balance of the speakers. I’ll make changing the drivers a last resort.

 

[radiotron_]

Try tightening the screws holding the drivers for the vibration issue.

Question, are you using the loudness and cranking the bass? If so then tightening the screws is still a good idea but most likely not your issue.

I’ll try tightening the screws on both of them. My receiver does not have a loudness feature, but does have “SUPER BASS,” which I only use rarely. Then the cabinet really rattles, which almost makes sense then. But it’ll rattle when playing a song with deep or heavy bass, at 2/5 of the knob turn, such as Judas Priest or especially Michael Jackson, even on balanced levels.

 

[radiotron_]

Update: I opened the speaker via taking the woofer off, and this thing is pretty sturdy on the inside. The front and back never rattled because there is bracing connecting them, but the speaker needs bracing connecting the sides. 3/4 inch MDF, not bad. I was expecting cheap cardboard thin wood.

 

[NH-MAN]

When you reassemble make sure the capacitor and resistor are not rattling against anything.

 

[quiet]

Rubber on the inside. Top, sides and bottom. Front and back if needed. Maybe 25% coverage. Peel and stick whatever. Stopping resonance with bracing works but can be a challenge. Skip the fiberglass.
Hope you can save the drivers. Would be great if you become happy with what you got.
Good luck.

 

[radiotron_]

Rubber on the inside. Top, sides and bottom. Front and back if needed. Maybe 25% coverage. Peel and stick whatever. Stopping resonance with bracing works but can be a challenge. Skip the fiberglass.
Hope you can save the drivers. Would be great if you become happy with what you got.
Good luck.

Thanks, I’ve already started cutting the wood, haha... if that’s doesn’t work well enough I’ll try rubber as well.

 

[radiotron_]

I’m going pure redneck here, having to sand the bracing poles down with... the driveway. Ya. All my tools are up at the farm.

 

[quiet]

Glue?

 

[radiotron_]

I mean rubber padding along with the bracing, if you meant to ask I’m using rubber glue

How do I glue? I was gonna put glue on the ends and then tap it in to place, but should I put it in place and then glue inbetween the cracks?

I’m using gorilla glue, is that okay?

I might use wood glue. I can adjust the piece before it dries.

 

[radiotron_]

I’ve got the brace in. I can’t fit a second one because the woofer is too big, but one should stop the unwanted vibrations enough.

 

[Lavane]

Another AK'r had a similar problem. It turned out the front speaker baffle came loose. No glue, not enough when built at the factory maybe. Running some glue around the baffle cured the buzzing.