Tweeter Protection Bypass Help

Charsbass

Charsbass

New Member
I have some Norman Labs speakers with problematic tweeter protection switches that I would like to bypass. I'm not very knowledgeable in crossover design and need some guidance as to how to rewire the connections. I will also replace the old caps while I am in there. You can see in the photo how it is now, thanks for any help in advance.

20170423_111503.jpg
 
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I would say replace your cap first, then see if it sounds better, those old caps can sure taint your sound!
DC
 
Charsbass said:
I have some Norman Labs speakers with problematic tweeter protection switches that I would like to bypass. I'm not very knowledgeable i n crossover design and need some guidance as to how to rewire the connections. I will also replace the old caps while I am in there. You can see in the photo how it is now, thanks for any help in advance.
Click to expand...

"Tweeter protection switches" are you certain that's what you have? Usually what manufacturers provide are tweeter adjustment switches and the purpose is to allow you to compensate for acoustically bright or damped rooms.

Any chance you could post a schematic of the xover?

Regards,
Jerry
 
Charsbass said:
It's definitely the protection switches, I have to reset them regularly even at low volumes.
Click to expand...

So they are like a breaker that trips? When they trip, do you lose all sound or just the tweeters?

In your pic, is the breaker the one on the top?

Regards,
Jerry
 
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If there's a button on the back of the speaker that says "RESET" it's not a level adjuster.

Looks to me like the + input (top left screw) connects to that black plastic block at the top. From there a line goes to the big inductor at top right, probably direct from where the input hits the black block rather than on the other terminal. So this is the woofer inductor. On the other terminal of that block, a cap is connected, likely the tweeter cap which is on the other side of this protection switch. So the pic is consistent with a protection switch or breaker.

I would confirm this by drawing your own schematic (we can help you with that) or find one on the web for this model.

If I am correct, you can disconnect the capacitor lead from the protection switch terminal and connect it where the input and the woofer inductor are connected, on the other terminal of the switch. The speaker will operate exactly the same except the faulty protection switch is now out of the circuit.
 
Hard to say on some early caps, but if it's a film cap they seldom go bad.

As far as bypassing, just solder a wire across the two terminals of the breaker. Of course, then if there is something actually wrong upstream the breaker won't kick out.
 
Yes, that makes perfect sense to me now that it was explained that way. It must be a tweeter cap since it is connected to a High/Normal/Low attenuation switch for the tweeter. Thanks for the help!
 
The Black body/ Red ends caps needs to be replaced/. They fail. Have seen pics of the caps blowing up. The breaker can be replaced with a fuse of the same amperage . If the value of the cap is low it can be replaced with a film cap, or get a Non polarized Electrolytic cap of the same value. Parts express or Parts Connection for caps.
 
Parts Express used to have tweeter circuit protectors too. The work relatively well in most cases, but I have seen even the good one fail in protection!

Ditto on the black caps with red ends- they are at least 20~30 years old, way past heir prime. Every time I see one I yank it out and replace them with a suitable 100+ volt, same uF rating poly/ film and sometimes an electrolytic cap.
Good luck you are well on the way to a much better sound.
DC
 
Thanks everyone, I successfully bypassed the protection circuit and replaced the caps with Dayton Audio 1%. A nice improvement indeed.
 
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