Loudspeaker Magnets and CRT TV Tubes

[Alex2507]

I might have picked a bad example. I used it as I use those drivers, and knew where to find the pictures. However the shield will cost the same if the driver is $20 or $200. In fact I think that shield is cheap. The cost of Mu metal is significant.

Anyhow there must be price point issues otherwise all drivers would have them and few do.

I recognized the driver as the ones used in your system. I'm sure that I have yet to hear anything of that calibur. The speakers listed in my sig are all shielded and can be had new and with full warranty for $850 if you know where to get 'em. Granted you can pay more if you buy 'em at Crutchfield. My set up is the nicest that I have heard in real life SQ wise due to speaker placement and calibration and because I don't know anybody else as "into" this as I am. Bottom line: to me shielding is dirt cheap.

Edit: In my case I wish my speakers didn't have the shields as it affects SQ according to WmAx. They will be removed before it's all said and done.

 

[sparky77]

Magnetic shielding when added to a speaker can have an effect on its magnetic related t/s parameters. The majority of speakers that include shielding take this into account in the design process.

One way of shielding is to use a bucking magnet that is glued onto the back of the speakers magnet with the poles reversed, the other is using the Mu-metal that tlsguy spoke of, unfortunately metal shields work better at keeping emf out of the shield rather than in.

If anybody wants to try experiment I found a site that has all kinds of shielding supplies.

http://www.lessemf.com/mag-shld.html

 

[TLS Guy]

I recognized the driver as the ones used in your system. I'm sure that I have yet to hear anything of that calibur. The speakers listed in my sig are all shielded and can be had new and with full warranty for $850 if you know where to get 'em. Granted you can pay more if you buy 'em at Crutchfield. My set up is the nicest that I have heard in real life SQ wise due to speaker placement and calibration and because I don't know anybody else as "into" this as I am. Bottom line: to me shielding is dirt cheap.

Edit: In my case I wish my speakers didn't have the shields as it affects SQ according to WmAx. They will be removed before it's all said and done.

Dirt cheap to a home constructor and a manufacturer are different concepts. To them having the right market price point and turning a profit are important considerations. And yes a shield makes it hard to vent the pole piece.

 

[WmAx]

Edit: In my case I wish my speakers didn't have the shields as it affects SQ according to WmAx. They will be removed before it's all said and done.

Note: my reference to shielding having a negative effect on sound quality was specifically in reference to certain drivers that had improperly attached shielding that caused a high pitch vibration/buzz artifact in certain circumstances.

-Chris

 

[Alex2507]

Note: my reference to shielding having a negative effect on sound quality was specifically in reference to certain drivers that had improperly attached shielding that caused a high pitch vibration/buzz artifact in certain circumstances.

-Chris

Hi Chris,
The drivers in this case are from the Infinity Primus line and are listed in my sig. I just wanted to ask you what those certain circumstances are. I rarely if ever listen beyond 70db.

Alex

 

[WmAx]

Hi Chris,
The drivers in this case are from the Infinity Primus line and are listed in my sig. I just wanted to ask you what those certain circumstances are. I rarely if ever listen beyond 70db.

Alex

What were the odds? The drivers used in the Primus 360 are some of the units susceptible to this problem. The issue is the metal shield can is glued to the back of the bucking magnet on the rear of the driver. However, the part of the can around the driver magnet is a very tight tolerance, just barely larger then the magnet. So close in fact, that if you knock on the can with a knuckle, you can hear the can rattle with a sort of rapid buzzing sound, as it vibrates against the magnet. The effect, apparent at even moderately low volumes on some musical material, may sound like slight 'distortion'. But it's no distortion -- it's that darn poorly attached shield. Of course, it could be that your particular example has better clearance of the magnet. But I have seen a few of these Primus units, and all that I observed had the same issue.

BTW, if you open up the speaker, you may as well do other mods to improve performance.

 

[Alex2507]

I will get to the modification of these speakers just as soon as I finish a few other projects like painting our dinning area, currently it's PINK, and completing the building and installation of an in wall entertainment center. I've got your instructions saved on my subscribed threads for future use.

I did have my old 250's apart just to take a look and I gotta tell ya, it's tight in there. Since then I upgraded to the speakers listed in my sig. The 360's are a little bigger which will help. I'm really looking forward to this.