Heresy center channel

[Chris Elm]

Hi folks,

There was a recent post in 2-channel about a Heresy center. It had all Alnico drivers and a special crossover and would not affect the magnets in a CRT.

What would be involved in retrofitting a Heresy I already own to not affect my television? Or which components (K-22-E, K-77M, etc.) are needed to accomplish this?

[DrWho]

All you need are bucking magnets.

Another alternative I've found is to just mount the heresy wherever you want to put it and then use a "electromagnetic wand" (that's what they're called) to undo the magnetic flux induced on the TV. This is what I did when I had my heresy between my Chorus I's.

[Malcolm]

The Heresys with the CTS or Eminence alnico woofers will give you the least problems around a TV set. Retrofitting a newer Heresy just consists of unmounting the old innards and mounting the new ones. Everything may change, certainly the woofer and network, the squawker driver and maybe horn if it is not a K-55-V on a K-700, and the tweeter if it is not alnico. But it is no big deal. The holes in the motor boards are the same size. Seems to me it would be easier to just replace the whole speaker, though. You can always sell the old one.

Don't know how a TV will fair with the even earlier ones with an EV SP12B for the woofer. It isn't the fact that the magnetic material is alnico that makes these things better around TVs. It is the design of the magnet circuit. The ones with what looks like at D shaped piece of steel wrapped over the pole piece, possibly with aluminum filler plates on either side, are the ones that work well. Some other alnico designs, like the ones with big round ring magnet assemblies, are just as bad as any of the ferrite designs around TVs.

Bucking magnets may be an equally effective and less trouble.

Degaussing can remove residual magnetism on the shadow mask caused by moving a magnet too close to it, and therefore fix the corresponding image problem. But it will not do a thing for the effect on the CRT's electron beam of the magnetic field of the speaker itself. You will still have a problem with the picture. All you can do is shield the speaker, shield the TV, change the relative positions of the TV and speaker, or use a bucking magnet to change the shape of the magnetic field.

[Chris Elm]

Thanks for your replies!

So this begs the question, how much would it cost for the bucking magnets, what all is involved in making the switch, and if I change out one, should I change out the other (I have a matching set of 88 HIIs I plan on using one for front and one for rear center)?

Thanks

[DrWho]

$50 for a pair? You just glue the bucking magnet to the back of the

speaker magnet such that the polarity is making the magnets want to

push apart. The end result is a cancellation of the magnetic flux on

the outside, and the magnetic field inside the voice coil gap doesn't

change. You really shouldn't have to put bucking magnets on every

speaker in order to maintain timbre matching.