Installing Bucket Magnets

Hey folks, im getting ready to install some Bucking magnets in my JM Lab 707s and a pair of Velodyne Subwoofers in order to shield them for the TV.

Looks straight forward, epoxy the magnets to the rear of the drivers.

Has anyone done this before? Any complications you have come across that i should know? Any advise?

This changes the electrical parameters of the drivers which needs to be accounted for PRIOR to the final design of the speaker. Proceed at your own risk. Sean
Hi Slappy,

The added mass to the rear of the driver will change its resonance characteristics. The voicing of the speaker system in the range of that driver may be affected.


Barry Kohan
While Sean is 100% correct that the magnets will change the driver Q, it is ever so slight that I know of no one that could hear a difference.

5 minute epoxy works very well and if you don't like the sound after installing them just take a sharp chisel, work it around the edges and pry the magnets off.
So i oughtta find a non-permamant way of doing this to see if there are any ill effects on the speakers?

can you see any potential permamant damage that might be caused by this?

still kinda pisses me off they are make without shielding, you'd think any speaker series that includes a center channel would normally have shielding on the entire line.
If this is one of the servo controlled subs, be careful. Changing the electrical parameters of the speaker may make the servo system unstable.
Not a servo sub. DLS-4000, top of the line model of a mid level product line. LOL
Every answer posted is the correct answer. I used in the past bucking magnets to make a shielded center speaker before ther was such a thing..We used silicon and wire ties to hold everything in place till all was cured. The sub may not be a factor...because of location and height relative to the crt's placement..Tom
Thanks for all the feedback folks, i should have the magnets by this weekend and should have everything done by next week. Ill be sure to post my results. :)
Do the SW actually distort/discolor (discolour for sean) your picture? Why not just move them away a bit. SW are sort of free to roam around the room.
What's wrong with shielding instead of adding the bucking magnets?

My understanding is the TI (Texas Instruments) FerriShield works to resolve this issue and it can be cut and pasted into the speaker cabinet without fear of harming the components or changing the sound.
Hey Eldartford! Seems like i havent seen you in the threads as of recent! Good to see ya.

Subwoofers can be moved, i just purchased a new rack that will be delivered wednesday that will free up a bit of space but not a whole lot.

the problem is this, check out my virtual system and note the space to the left of the left speaker, well, thats a staircase. moving the speaker will result in way too much of a "speaker down the stairs" scenario with all the dogs i got running around. (grin) Placing the sub near there really doesent yield any bass responce in the sweet spot.

The speaker on the right, about 1 foot to the left is the door to the garage and on the side wall in the corner there is the front door. So, space is a premium there too.

The only sub i currently have set up has to be against the wall facing left just to prevent it from messing with the picture. moving it to the right of that speaker it will be in the way of the doors, swapping its location with the speaker causes the speaker to mess with the picture.

Ive got a couple projects in mind for the living room and one of them while it is being done will allow me to run a full set of AV cables to the wall behind the couch which cannot be seen, there is a corner there which would work wonderfully, however, getting it there at this time is kind of a problem, and i have several projects i need to finish before i start any more. Hell, im turning into a regular bob villa, this weekend alone i shingled the doghouse, dug the pit for the sandbox in which the hottub will be, and replaced a good portion of my granite countertops that were incorrectly done by the prev owners, and i did it with style!!!!! Nice Inlay work of several types of granite. (laugh) Getting kind of off topic there but im pretty proud of myself. (ROFL)

So, im thinking at this point the easiest would be to try to shield the speakers and subwoofers. Ive tried so many different placements, but i have very limited luck, if they diddnt mess with the picture it would really open the possibilitys of placement.

but i guess to answer yer question yeah they do mess with the pic. In fact it is bad enough ive only found one plausable location for the SW (without running cables, which im not against, however, i need to finish some other projects before i start one that would make it possible unless i wanted to crawl through 18 inches of insulation in my vaulted ceilings.. hell, i can see it now, roomate coming home, slapster is nowehre to be found.. weeks go by.. then the roomate starts to notice a smell.... ) and to have both subs running they have to be stacked on eachother in that exact spot.

(the other sub is currently in my buddys system in the basement.... but not for long...oh no... not long at all... MWAHAHAHAHAHAHAHA)
Why not obtain some mu-metal and install a layer inside the cabinet on the side facing the TV? Minimal changes to driver parameters, less loss of internal space than large magnets ( which nobody else mentioned and will change the tuning of the box ) and probably more effective overall.

One question though: Why are your speakers ( other than a center channel ) and subs so close to your TV that they cause problems? If the speakers are that close together, there's no need for a center channel as there is no separation from left to right as it is. Even with the 55" RPTV that i have, there's not quite 48" from side to side. While a larger TV would space them further apart, even 5' is too close together for stereo, let alone HT use with a center channel.

My guess is that you would benefit more from re-positioning your speakers than doing anything else to the system. The good news is that this is free and completely reversible if you don't like the results. Sean
Albertporter, the answer to that is pretty simple. I never heard of it. (LAUGH)
I had a thread out a while back asking about shielding, and the only response i got was Bucking Magnets, figured that was about it. LOL

Im looking on the net, not coming up with anything too solid on it though....... you know any dealers for this off the top of yer head?

Albertporter, the answer to that is pretty simple. I never heard of it. (LAUGH)
I had a thread out a while back asking about shielding, and the only response i got was Bucking Magnets, figured that was about it. LOL

Im looking on the net, not coming up with anything too solid on it though....... you know any dealers for this off the top of yer head?

there it is
Sean, see above post to elartford about speaker placement.... on my virtual system, you can see where they are, any closer and they start messing with the picture. any further out and one will probably get knocked downstairs and the other will be in front of the door to the garage. (LOL)

Honestly, i hardly use the crappy center speaker i got when watching movies, normally i just run phantom mode which works fine for me, the imaging on these really does get the dialogue dead center. Well, unless yer pretty far off axis, but damnit, when i watch a movie im in the sweet spot, everyone else can just deal with it. =)

Mu Metal? Never heard of it but i will definatly explore that possibility as well! Thanks for the tip!

Im not absolutly sold on Bucking Magnets, That was all i got though in a thread i put out a while back about how to do it. So i figured that was the only real way.

Ill hit the net looking for Mu Metal as well, any rec's on a good dealer?

I know that Michael Percy sells some shielding kits, but i don't know exactly what he offers or how expensive it is. Doing a search on the web might turn up some "non-audiophile" suppliers with both a wider variety and slightly better pricing. Sean
Welp, this problem was solved.
I got my new TV stand and with the increased highet of the stand im no longer having any trouble with magnetic interferance.

THose magnets should arrive today. Guess ill use em to make sure that my grocery list stays on the fridge.