Help! Passive radiator replacement

JKent · « **on:** 28 Apr 2006, 09:58 pm »

I purchased my "Smaller Sub" (now known as the Dedicated) in 1985. A few years ago I replaced the driver because the foam surround had rotted. Now I discover that my passive radiator has suffered the same fate. How do I fix this?
The radiator on this model was obviously installed before the bottom panel. If I look through the vent slot I can see the screw heads, and the flange of the speaker basket is on that side of the baffle. The bottom panel is stapled on but I suspect it is glued as well. Is that correct? How do I change the radiator?
This sub is in my "rec room" these days and not used much, but I was planning to install a plate amp. Now the first priority is replacing the radiator.
Also--once I get the radiator out--where should I look for a replacement?
Thanks

rosconey · « **Reply #1 on:** 28 Apr 2006, 10:44 pm »

buy a refoam kit off ebay or contact big b and buy a whole pr from him

JKent · « **Reply #2 on:** 28 Apr 2006, 11:00 pm »

Quote from: rosconey

buy a refoam kit off ebay or contact big b and buy a whole pr from him

Didn't exactly answer the question: HOW DO I GET THE DAMN THING OUT????

rosconey · « **Reply #3 on:** 28 Apr 2006, 11:03 pm »

give it a day and one of the oldtime dealers will have the answer-or pm
ribbonspeakers-great guy

JKent · « **Reply #4 on:** 29 Apr 2006, 12:19 am »

Quote from: rosconey

give it a day and one of the oldtime dealers will have the answer-or pm
ribbonspeakers-great guy

Heard from Brian. This is his advice. No kidding. I'm NOT making this up!

"You can detach a glued-on baseplate by tapping the lip with a sledgehammer and 2x4."

warnerwh · « **Reply #5 on:** 29 Apr 2006, 01:20 am »

You may want to put a rag between the 2x4 and hammer. It's just wood glue holding it on so it will probably pop right off.

Brian Cheney · « **Reply #6 on:** 29 Apr 2006, 01:36 am »

We did that glueing on the base trick only in 1984 and 85. The glue should be brittle by now and a few taps with the hammer and 2x4 makes it loosen up.

Reattach the base with woodscrews once the PR is replaced.

20 years is pretty good service. The replacement PR is $42.

JKent · « **Reply #7 on:** 29 Apr 2006, 02:54 am »

Quote from: Brian Cheney

We did that glueing on the base trick only in 1984 and 85. The glue should be brittle by now and a few taps with the hammer and 2x4 makes it loosen up.

Reattach the base with woodscrews once the PR is replaced.

20 years is pretty good service. The replacement PR is $42.

Thanks Brian, but seriously--a sledgehammer?! Let's use a little finesse

I used a 16 oz. hammer, a block of hardwood and an old towel. The glue was still pretty tight, so it took more than "taps" but not sledgehammer blows! Then there were the 16 finishing nails.

About the PR: I'll contact you regarding shipping to NJ, payment. Are the new PRs improved or can I expect this one's surround to deteriorate as well? (For that matter, what about the new driver I put in a few years back?). Does it come with directions? I know you used Mortite to dampen the cone back in the day. Should I also use Mortite on the PR flange? And if I reattach the base with screws, should there be any kind of sealant used there? I plan to install a plate amp while I'm at it. I know you recommend the "1000" watt (really 500 into 8 ohms) from PartsExpress, but I saw a 250 watt with remote control from Apex that is more attractively priced and I'm planning to use taht instead. Anything I'm overlooking here? Thanks for the help.

warnerwh · « **Reply #8 on:** 29 Apr 2006, 04:09 am »

Modern foam surrounds will last longer than older ones due to new additives making them more ozone resistant. They should last at least 20 years. The older foam usually was gone in 10-15 years. Foam is an excellent material for a surround being low mass and rigid. People seem to frown on it a bit but it's better than many other materials and refoaming drivers is easy and doesn't take long.

For the money he's charging for a new passive radiator I wouldn't worry about it. 42 bucks ready to go I'd be happy. I think he should charge significantly more. Foam surround kits alone usually run a good 30 bucks with shipping for the better kits. At least they have for me redoing 8" and 10" drivers in Advent and Infinity speakers I've owned.

JKent · « **Reply #9 on:** 29 Apr 2006, 06:47 pm »

The saga continues--phoned Brian today to order the PR. Good thing I talked to him. I thought this sub was called the "smaller." I bought it in 1985 for a whopping $279.00 (it was a "kit"). Turns out it's the "original." Has a 12" driver but a 15" PR. Brian set me straight and fortunately I ordered the correct PR. Can't wait to get this put back together

JKent · « **Reply #10 on:** 6 May 2006, 04:27 am »

Got my plate amp today and installed it. The Apex Senior. Wow--that subwoofer box is tough stuff. The Apex has a remote control, so the trickiest part of the installation was mounting the RC panel on the (cloth-covered) front of the sub. I think I have it figured out, but am a little concerned about air leakage, Think I'll apply some foam weatherstrip.
Just waiting for the PR now.

warnerwh · « **Reply #11 on:** 6 May 2006, 05:18 am »

You can also use some silicone to make sure there's no air leak.

JKent · « **Reply #12 on:** 6 May 2006, 12:49 pm »

Quote from: warnerwh

You can also use some silicone to make sure there's no air leak.

Thanks warner. The reason I thought foam tape is because of the construction of the woofer. There is a 3-panel fabric-covered assembly for the grille cloth. I cut a 2.5x6" hole in this to mount the remote control receiver. Also cut a hole in the speaker enclosure. Since that grille assembly is semi=removable, I want a non-permanent seal between it and the speaker box. Thought the tape would work. btw--the plate amp itself (and the remote receiver) have foam gaskets, so I think they're ok. Thanks for the advice. All tips welcome!

JKent · « **Reply #13 on:** 7 May 2006, 02:30 am »

OK--guess I need a lot of hand-holding. So here's my next question: The plate amp is open in the back. There is a picture here:
http://www.apexjr.com/Apexsenior.htm
so can I just cut a hole in the VMPS sub and screw this on, or do I have to fabricate a box to recess it in? Guess the same question would apply for the remote control module. thanks

warnerwh · « **Reply #14 on:** 7 May 2006, 04:47 am »

You can just bolt it to the cabinet. Be sure to cut out a hole that will let the gasket seal nicely. Better to cut a little too small at first if you are not handy at this like me. Then obviously if need be you can open it up a bit more if need be.

Brian has the greatest idea when screwing something to mdf. Use drywall screws. These hold tight even with all the vibration even over a long period of time. I know as I've checked mine over the years and they stay tight.

You don't need to drill a pilot hole for drywall screws, just drive them in with a cordless drill and bit or with a screwdriver just forcing it in. Don't overtighten the screws and strip the hole. You just want a nice snug seal.

Tighten the screws til they're just to the edge of your plate amp. Then tighten one part way tight. Directly across on the other side of the amp from that screw tighten that screw halfway tight. Then go through the same procedure with all of the screws. Do the same thing on the second round to tighten them up all the way and remember don't muscle them in.

This will bring the edge of the amp down evenly and will insure a good even seal. I'm assuming there's a rubber gasket on the edge of your plate amp as I couldn't tell in the picture. If there is a rubber gasket don't use any weatherstrip.

OTL · « **Reply #15 on:** 8 May 2006, 09:48 pm »

Strongly suggest you put down the electric driver and use a a regular screwdriver to snug 'em down the last 1/8 in or so. If you overtighten, even just a 1/2 turn or so you've drilled a hole instead of tightening a drywall screw.

Personally, I'm not real comfortable with a powered screwdriver anywhere near a speaker cone, but YMMV.

john1970 · « **Reply #16 on:** 8 May 2006, 04:26 am »

To all,

I would never place an electric screwdriver near a speaker cone (or any other easily damaged material). The torque from the drill can easily cause it to slip. Best to use a screwdriver with a large diameter handle. I use a ratcheting Crescent screwdriver with interchangable bits.

Just my advice,

John

JKent · « **Reply #17 on:** 9 May 2006, 09:47 pm »

Quote from: warnerwh

You can just bolt it to the cabinet. Be sure to cut out a hole that will let the gasket seal nicely. Better to cut a little too small at first if you are not handy at this like me. Then obviously if need be you can open it up a bit more if need be.

Brian has the greatest idea when screwing something to mdf. Use drywall screws. These hold tight even with all the vibration even over a long period of time. I know as I've checked mine over the years and they stay tight.

You don't need to drill a pilot ...

The plate amp came with a gasket and a set of wood screws that seem to work fine. Got the plate amp in and tightened the screws with my little Milwaukee 2.4 volt screwdriver (no chance of over-torquing and stripping the threads). Installing the optional remote on the front of the sub was a pain. At first I thought I'd install it on the surface of the grille cloth board, but that posed some problems with getting a good seal and with being able to remove the grille. Finally decided to mount it on the sub and cut a hole in the grille cover board. Of course I should have removed the grille cloth, but I was afraid I'd have trouble getting it back on right. If you don't already know, cutting the hole while the cloth is still on is a dumb idea

. Anyway--got the hole cut, and since the cloth was not cut in a way that would allow wrapping it around the edges, I made a little wood frame or bezel. Not sure how I like it. There are a couple of snags in the cloth, so I may end up replacing it after all. Now just waiting for my new passive radiator so I can fire this puppy up! btw--is there a way to post pics here?

JKent · « **Reply #18 on:** 15 May 2006, 06:17 pm »

I think this is the end of the saga. Got the new PR and installed it. Put it all back together and it works fine. Only problem I've encountered is my 14-yr-old Sony STR-GX57ES receiver does not have an output for the subwoofer amp. No problem--I can run the L&R speaker wires to the plate amp, and from there to the speakers. Only problem is, I guess the receiver sees the combined load of the 8 ohm VMPS and the 4 ohm Allison Fours. That probably makes a near-short, so the receiver's protection circuitry shuts it down if it hits a demanding passage. Oh well...maybe time to replace that receiver