Norman Lab Model 9

Subnormyle

New Member
First off I apologize if I should have posted this in the DIY Section, I debated with myself and chose to post it here.

Moved to Oklahoma in 1995 and a friends dad had a pair of Norman Labs Model 10. I fell in love and vowed to own a pair one day. They were built less than 10 Miles from the first house I lived in when I moved here, In fact I will be driving past the factory they were built in tomorrow morning on the way to work.

Well last weekend I finally picked up a set of what i believe are late 70s Model 9s. Part nostalgia and part saving a local legend. The cabs are a little bit rough but not bad at all. They have the paper cones with rubber surrounds. They sound fantastic and played great the first day I had them home. Second day I started having issues with the breakers. Read on here a bit and decided to temporarily bypass the breakers by stripping the jacket off some old speaker wire, wrapping it around the breaker terminals and twisting it tight. I'm sure some won't approve but like I said its just temporary.

I plan on freshening them up a bit but have a few questions.

1. Has anyone used the automatic reset speaker circuit breakers from Parts Express? Would these be OK to add internally in place of the push button breaker. I want to leave the push button installed but disconnected. Specifically I'm looking at the 2.0A 150W units. I read in an old thread here the breakers were rated at 2.0A.

2. I am a little confused on what Caps to buy to replace the originals. There are 2 caps in each speaker. The large cap reads 15uF-75VAC, and the second cap which is about a quarter its size reads 15UF100VNP. Now are both of these caps the same value? can I just get 2 15uF Solen caps to replace them?

3. Should I replace the light bulbs in the tweeter protection circuit? They do not light up while the speaker is playing. Is there enough voltage that they should light up, or would they be so dim i wouldn't be able to tell. I haven't grabbed by multimeter to check them yet but I almost feel replacing a 30+ year old light bulb is a good idea.

Thanks a lot guys, I would appreciate and input or advice you are willing to provide. Here are a few pics of the 9s.











 
Those look great! I just re-foamed a pair of Norman 7's and am about to refinish the cabinets. They have the same type breaker, but mine are working fine at the moment.
 
The light bulbs in the circuit will only light when too much voltage is applied to the tweeter. It takes a lot of power to make them light. I imagine they are still good and don't need replacement.
 
I plan on freshening them up a bit but have a few questions.

1. Has anyone used the automatic reset speaker circuit breakers from Parts Express? Would these be OK to add internally in place of the push button breaker. I want to leave the push button installed but disconnected. Specifically I'm looking at the 2.0A 150W units. I read in an old thread here the breakers were rated at 2.0A.

2. I am a little confused on what Caps to buy to replace the originals. There are 2 caps in each speaker. The large cap reads 15uF-75VAC, and the second cap which is about a quarter its size reads 15UF100VNP. Now are both of these caps the same value? can I just get 2 15uF Solen caps to replace them?

3. Should I replace the light bulbs in the tweeter protection circuit? They do not light up while the speaker is playing. Is there enough voltage that they should light up, or would they be so dim i wouldn't be able to tell. I haven't grabbed by multimeter to check them yet but I almost feel replacing a 30+ year old light bulb is a good idea.

Thanks a lot guys, I would appreciate and input or advice you are willing to provide. Here are a few pics of the 9s..


Very nice audio system and those Norman Lab model 9's look right at home.

Your speakers were made in 1979.

Those circuit breakers are there to protect the tweeters. I've had to "reset" the breaker often. I usually just try to clean the original breakers before replacing them, most sit forever and never get used once, just a little movement from time to time will help keep them functioning correctly. I don't specifically recall using the circuit breaker from Parts Express probably because I have a box full of NL crossovers from parted out speakers. The circuit breaker is 2.1A

As to what caps to purchase, that's really up to you but I wouldn't buy into all the hype and marketing of certain capacitors, higher cost doesn't necessarily mean better. A good solid replacement of the correct value is all that's needed. I've use Dayton's in a lot of NL speakers but Solen's would be fine, it's an experiment either way. Just keep in mind, recapping is something you can do fairly cheap but don't expect big results, if you can notice any changes at all, it will be subtle. Don't put too much stock into the size of capacitors, especially comparing older capacitors to newer capacitors. Keeping the correct microfarad value is the most important. Most of the time voltages on newer caps will far exceed the voltages in old caps in a similar size comparison and baring a major malfunction, you'd never get anywhere close to the voltage rating. I would think, 2 - 15uf caps of your choice would work fine. The smaller cap you mentioned is just a non-polarized capacitor [NP]. A lot of manufacturers simply use parts they can purchase for the best price, that will fit in a particular space for their intended application.

I wouldn't bother with replacing the blub in the crossover. Some of today's replacement parts are made so cheaply in comparison. If the bulb is good, I'd leave it alone, you're not really improving anything by changing it. It is not desirable to attempt to make the blub light up, it is there to serve as a protection fuse, not entertainment.

Let us know how things turn out.
 
I appreciate all your information. I was debating between the Dayton and solen caps. I will probably use the daytons. My biggest concern was the size difference between the two 15uF caps, thanks for the clarification. I will attempt to exercise the breakers, hopefully they will clear up. I've read many NL post here and you seem to be as close to an expert as possible with these great speakers. Thanks a lot.
 
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